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Physical and ieical Examination 
 of ? 
 PAINTS, VARNISHES, 
 LACQUERS AND 
 COLORS 
 
 By Henry A. GARDNER 
 
 DIRECTOR SCIENTIFIC SECTION, EDUCATIONAL BUREAU 
 AMERICAN PAINT AND VARNISH MANUFACTURERS’ ASSOCIATION 
 
 FOURTH EDITION 
 OCTOBER, 1927 
 
 7 
 
 Published by 
 
 Institute of Paint and Varnish Research 
 2201 New York Avenue, northwest 
 
 Washington, D. C. 
 
Pe? : Copyright 192 
 # By Henry A. Gar 
 
DEDICATION 
 
 To the Hon. Hersert Hoover 
 U.S. Secretary of Commerce 
 
 Under whose helpful engineering guidance and en- 
 
 couragement, many problems have been solved by 
 
 workers in the paint industry, this volume 1s respect- 
 fully dedicated. 
 
Chapter 
 
 I 
 II 
 Ill 
 
 XI 
 XII 
 
 XIII 
 XIV 
 ». O's 
 XVI 
 XVII 
 XVIII 
 XIX 
 
 XX 
 XXI 
 XXII 
 XXIII 
 XXIV 
 XXV 
 
 b. ©. G6 | 
 XAVIT 
 XXVIII 
 XXIX 
 XXX 
 
 XXXI 
 XXXII 
 XXXITI 
 XXXIV 
 XXX V 
 XXXVI 
 ».0:0.4'8 8 
 XXXVITI 
 XXXIX 
 XL 
 
 XLI 
 XLII 
 XLIII 
 XLIV 
 
 Contents 
 
 Page 
 Hiding Power and Brightess.:..... (nese «ei = ae secre 
 Consistencecy—Viscosity, Plasticity, Mobility................ 351 
 Hardness and Abrasion Resistance. ...... i. se. «+ ssw ere 59 
 Gloss Measurements on Paint...... URGE ETS oe ee 89 
 Tensile’ Strength. and Elongation. ..:22s..00 «4 see 97 
 Film Phickfhess .. 0.06. 40 bab oo opie m oinuel ene tee ine nan < 108 
 Drying Time of Films. ... . os e004 p05 gece mnie ete 110 
 Temperature and Humidity Control Cabinets...............:; 122 
 Specific Gravity Determinations.................. eee mony aly 136 
 Determining Coarse Particles in Paint Pigments............. 151 
 Particle’ Size of Paint Pigments. ©. UJ: 9 io. 0. oe 165 
 Surface Tension and Interfacial Tension of Varnishes and 
 Paint. Liquids... 5.295 oe eee TEs be es Gee 174 
 Ultraviolet Light Studies on Paint Pigments and Liquids.... 183 
 Testing the ‘Light Resistance of Lithopone.................. 193 
 Color Systems, Colorimeters and Spectrophotometers........ ZG 
 Oil. Absorption. Tests. . . ... «ss a's «cleo mie ale ee ean 
 Texture of. ‘Pigments. soe. «. 2. apo 0 oon Shee 276 
 . Miscellaneous Physical Testing Devices and Methods........ 281 
 Testing White Opaque Pigments for Some Physical Prop- 
 erties (Routine: Methods) . 2.2... i sv cans wee 300 
 Testing Colors for Tone and: Strength. .7 sane eee eee 305 
 Accelerated Testing Cabinets... ....2.. ss «eas ele aunt 309 
 Hxposure TestS 2.0.20 ccs ss 6 0m winte Ole bly een eyes enna 541 
 Analysis of Paint Oils... 5.05.0. eu yee elena een eee 401 
 ‘Analysis of VarnisSl i... 5.5 5 6 ooo 6 wise intent iemaiene tae ne 447 
 Miscellaneous Tests on Varnishes................ er. oe 465 
 Color Standards for Varnishes...... +3 ele ely vig tp es 479 
 Analysis of. Mixed Driers. .i.....<0<e...ses a 485 
 +Examination and Analysis of Varnish Resins................ 488 
 Shellac Analysis: 0.4 ....05 5040085 0 6 © 5 tm pe sie ee inne anne 516 
 Bituminous Paints, Varnishes, Cements and Automobile Black 
 Baking Enamels’ . 006%) 2-440 6s «s « <9 soles 5385 
 Examination of Turpentiné and Mineral Spirits............ 551 
 Examination of PWlaxseéed. .. 2... fs. ele eae eiere ie sna een 569 
 Examination of Waxes and Polishes... 2... 2.5.05 see 575 
 Testing Raw Materials Used in Lacquer Manufacture....... 579 
 Analysis of Pyroxylin Coatings.... 2... 4.0 eee ee 595 
 Physical Tests on Pyroxylin Lacquers.) .....5 ee 3 612 
 Miscellaneous Methods of Testing Materials................ 649 
 Analysis of Paints. . o. cic sce oc visie mou aly eereing nen ete 676 
 Analysis of White Pigments; ., 00... ics stew) eyes cee 697 
 Analysis. of Lead Oxides... 5. .<< ssc os es es oe ee 718 
 Analysis-of Reds other than Iron Oxides... ..... 5.59 eee 728 
 Analysis of Yellow, Orange, Blue and Green Pigments....... 736 
 Analysis of Black Pigments. ..... ss: a's sss sia iis ane . 156 
 
 Analysis. of Iron Oxide Pigments: ........ uc .csinueneeee fio LOO 
 
PREFACE 
 
 A revision of the previous edition of this book has been 
 necessary on account of the rapid advances which have taken 
 place in the paint, varnish, and lacquer industry during the 
 past few years. An attempt has been made to bring the book 
 up to date and to include all modern methods for the physical 
 and chemical testing of raw materials and finished products. 
 All the latest specifications of the American Society for Test- 
 ing Materials are included and given preference over previous 
 matter which appeared in the earlier edition and which was 
 usd in drawing up many of these specifications. 
 
 There are also included in the back of this book twenty-nine 
 specifications of the Federal Specifications Board, which are 
 used by various departments of the U. 8S. Government for the 
 purchase of painting products. These specifications, which 
 have just been printed by the U. S. Government Printing Of-_ 
 fice after having been carefully revised, by P. H. Walker of 
 the Federal Specifications Board, include several which were 
 not present in the previous edition. 
 
 The writer is greatly indebted to the following for aid in 
 the preparation of the book: G. G. Sward, A. W. Van Heuck- 
 eroth, and P. H. Butler of this laboratory; P. H. Walker, F. 
 W. Smithers, H. D. Bruce, L. L. Steele, I. F. Hickson, and 
 K. H. Berger of the Bureau of Standards; J. A. Schaeffer, 
 fede und. ds. Hi. Barton, F..G. Breyer, P. R. Croll, H. A. 
 Nelson, W. R. Fuller, A. F. Brown, H. C. Parks, D. V. Gregory, 
 feels, M. Kk. Paul, D; A. Kohr, C. Hall, and other 
 members of the industry. 
 
 Washington, D. C. 
 October 15, 1927. 
 
om 
 
CHAPTER I 
 HIDING POWER AND BRIGHTNESS 
 
 When a ray of light falls upon an object, part of 1t is re- 
 flected and the balance enters the object. That which enters 
 either finally emerges from other faces of the object or after 
 multiple internal reflection becomes absorbed. Thus when a 
 ray of light falls upon an aggregation of pigment particles 
 as in a layer of paint, the light which strikes the eye is com- 
 posed of that which is reflected by the surface of the paint 
 and that which after multiple reflection within the layers, 
 finds its way out. The opacity or hiding power of a paint 
 depends therefore upon the amount of ight which is reflected 
 before reaching the background. This reflection is propor- 
 tional to the total surface and to the refractive index of the 
 pigment, or more exactly, the difference in the indices of 
 media and pigment. A third factor in the hiding power of 
 a paint is the oil absorption of the pigment, in that it deter- 
 mines the amount of pigment which may be incorporated into 
 a workable paint. | 
 
 If pigments are produced of sufficiently large particle size, 
 they, will be somewhat transparent lke a lump of clear glass, 
 since all such products allow the light to be transmitted in 
 varying amounts. If these lumps are broken down and di- 
 vided into a very fine powder, the finely divided particles 
 reflect the light in all directions and only a small amount of 
 light is transmitted. As a rule, the hiding power increases 
 with fineness of division up to a certain point, beyond which 
 loss of opacity may be shown.* See page 662. The latter is 
 especially true of fume pigments. 
 
 Refractive Index.—The refractive index of a pigment deter- 
 mines the amount of light which will be transmitted by 11. 
 The higher the refractive index, the greater the reflection and 
 consequent hiding power. A layer of white lead will reflect 
 more light than a layer of finely ground silica, since the refrac- 
 tive index of the lead is higher than the refractive index of the 
 silica. As the refractive index of the vehicle approaches that 
 of the pigment, opacity diminishes. Consequently when these 
 
 * Larsen, Microscopic Determination of Non-Opaque Minerals, U. 8. Geo- 
 logical Survey Bul., 679, p. 13. 
 
10 Hiding Power and Brightness 
 
 pigments are ground in water, they are less opaque than in 
 dry form, because water has a higher refractive index than 
 air. When turpentine is used as a binding medium, the pig- 
 ments show the same relative differences in hiding power, but 
 both are less opaque than when in water, since turpentine 
 is more highly refractive than water. When linseed oil is 
 used as a medium, still less opacity is shown by the resulting 
 paints, as linseed oil has a greater refractive index than tur- 
 pentine. The resulting silica paint will now be practically 
 transparent, since the refractive index of linseed oil is sub- 
 stantially the same as that of the silica. The lead paint, 
 however, wiil still be opaque, since white lead has a refractive 
 index greater than that of the oil. 
 
 Opacity increases inversely with the amount of oil absorbed 
 by the pigment. Thus, for instance, if a white lead and a 
 zine oxide pigment should have the same refractive index, 
 the white lead pigment might show the greater hiding power, 
 since a paint made of white lead usually contains up to 70 
 parts of lead and only 30 parts of oil, while one made of 
 zinc oxide usually contains only 50 parts of zine oxide. When 
 used on the same volume basis, however, the zine oxide paint 
 would show superior hiding power because commercial zine 
 oxide actually has a greater refractive index than commercial 
 white lead. 
 
 The method of determining refractive index which has 
 been worked out by Dr. F. E. Wright* of the Carnegie Geo- 
 physical Laboratory of Washington, is to immerse the pig- 
 ment in media of known refractive indices such, for instance, 
 as piperine and antimony triuodide, or mixtures of them. 
 Wright’s method of oblique illumination is given below: 
 
 ‘‘The index of refraction of a grain embedded in a liquid 
 or other body and that of the embedding material can be 
 quickly compared by observing their line of contact under 
 the microscope and shading a part of the field by placing the 
 finger or a card beneath the condenser system, by tilting the 
 mirror, or in some other way. A number of devices have 
 been recommended for this purpose, and some of the newer 
 microscopes have special slides inserted. The observation 
 is best made with a low or moderate power objective and 
 
 *Methods of Petrographic Research, Carnegie Inst. Washington, Publ. 
 158, 92-95. 
 
Hiding Power and Brightness Te 
 
 without the condenser lens. With a low-power objective a 
 mineral that has a decidedly higher index than the lquid 
 will have a dark border toward the shaded side of the field 
 and a bright border on the opposite side. If the grain has a 
 decidedly lower index of refraction the phenomena are re- 
 versed and the bright border is on the shaded side of the field. 
 With the moderate-power objective and the condenser lens the 
 phenomenon depends on the position of the condenser. If the 
 focus of the condenser is above the object the phenomena are 
 as stated above; if below the slide, the phenomena are re- 
 versed. It is best to check the system used by making the 
 test on some known grain; a thin section in which orthoclase, 
 quartz, or some other known mineral is in contact with Can- 
 ada balsam is good for this purpose. At the same time the 
 difference in index of refraction between the grain and liquid 
 can be estimated by the relief and the amount of shading 
 required to bring out the relief. This method is equally well 
 adapted to thin sections and has many advantages over the 
 Becke method or the method of central illumination, as it can 
 be used with a low-power objective, and by it every grain in 
 contact with the Canada balsam ean be compared with balsam 
 in avery short time.’’ 
 
 Larsen* has deseribed an niente method as follows: 
 
 ‘As the immersion method is ordinarily used nearly all 
 fragments are thinner on the edges than in the center, and if 
 the fragments differ from the surrounding material in refrac- 
 tive index they will act as small imperfect lenses toward a 
 beam of nearly parallel light emerging from the condenser. 
 If such a lenticular fragment has a higher index of refraction 
 than the embedding medium it tends to focus the light above 
 its plane, and if the microscope is first focused on the grain 
 and then raised above focus the interior of the grain will ap- 
 pear more highly illuminated. As the microscope tube is 
 raised higher above focus this highly illuminated area con- 
 tracts and becomes brighter—a bright line moves into the 
 grain. If the tube is lowered below ‘focus the grain appears 
 less highly illuminated than the rest of the field and a highly 
 illuminated halo surrounds it. Ag the tube is lowered this 
 halo moves out from the grain. 
 
 “Tf the grain has a lower index of refraction than the 
 embedding medium it will have a virtual focus below its 
 plane, the phenomena are reversed, and the grain becomes 
 
 *Larsen. Microscopic Determination of Non-Opaque Minerals, U. S. 
 Geological Survey Bul., 679, p. 14. 
 
12 Hiding Power and Brightness 
 
 centrally illuminated as the microscope tube is lowered below 
 focus. 
 
 ‘‘In practice the test is best made with an objective of 
 medium or high power—one with 8-millimeter focus gives 
 good results. The condenser may be in or out. The con- 
 denser system may be lowered or the lower diaphragm closed. 
 The most suitable arrangement for a particular microscope 
 and. lens system can best be found by testing it with grains 
 embedded in media of known indices of refraction. 
 
 ‘‘Immersion media should be nearly colorless, chemically 
 stable, and without disagreeable odor or other objectionable 
 properties. They should not dissolve or react with the min- 
 eral to be immersed. Low volatility and for many purposes 
 a moderate though not too great viscosity are desirable. Each 
 liquid should be miscible with the liquids whose indices of 
 refraction are above and below it, and two liquids that are 
 to be mixed should have approximately the same rate of vola- 
 tilization, as otherwise the mixture may change rapidly. The 
 index of refraction should not vary too greatly with changes 
 of temperature. A low dispersion is desirable for accurate 
 work, but a rather strong dispersion facilitates rapid deter- 
 mination.”’ 
 
 There are presented below results on some pigmentary sub- 
 stances as given by Merwin or in the International Critical 
 Tables: 
 
 REFRACTIVE INDICES OF SOME WHITE PIGMENTS. 
 
 Refractive 
 
 Pigment Index Authority 
 Basic Carbonate White Lead. 26.50 140 oss 1.94—2.09 Merwin* 
 Basic Sulphate: White: Lead... i.c. sess eee 1.93 Merwin* 
 Lath Oponen.. Ses se wee wale edee eh Reh Seen wa bee 1.84 Merwin* 
 Fine OxeIde (AN) so... clcciee cee oe ca oe ee 2.02 Merwin* 
 Zine Sulhde © (ZS )) ac delet amcsoconc le Go ain er eee 2.37 Merwin* 
 Titanium Oxide TiO, ees eee joa lal gies eee 2.76 | ee We bf 
 Barytes:(.BaS0;) soa 25 ahs on <8 oe Sale cae ie eee 1.64 Merwin 
 OCaletiim (Sulfate suc heses uke so courte oe ae 1.59 Dae Se i 
 Aine  Bulnge cog 4 eee Oe ce ote vente ey cee ee 2.37 WeOe B, 
 Antimony “Ox: «civ aise ans ecue a apne le a ee 2.09-2.29 be BP 
 Siliea -StO, quartie ssi. cy eins Sela eas oh 155 ME 
 
 It must be remembered that most of the non-opaque pig- 
 ments are crystalline and usually possess different refractive 
 * Merwin, see page 153, this book. 
 yMerwin gives results on Lithopone ranging from 1.70 to 2.25, the 
 
 latter constituting 1%. These tests made previous to advent of modern 
 
 Lithopone. 
 tI. C. T.—International Critical Tables, Vol. I. 
 
 ) 
 i 
 | 
 | 
 
Hiding Power and Brightness 13 
 
 indices along the different crystal axes. The values given in 
 the above table are mean values for all directions. 
 
 Hiding Power Instruments.—Probably the most accurate 
 device for determining the hiding power of liquid paints is 
 that devised by Dr. Pfund, and described on page 14. This 
 instrument has found quite a wide application in the trade. 
 An apparatus was designed along a somewhat similar princi- 
 ple by the present writer, but giving direct readings without 
 manipulations of the clear glass cover top. Itis free from the 
 possible criticism of pigment accumulation at localized spots, 
 due to working back and forth of the cover glass. The base of 
 the apparatus (10 cm. in length and 214 em. wide) is of opaque 
 white glass or of opaque black glass, according to whether 
 white or colored paints are to be tested. At the end of the 
 base is a metal piece made of German silver, permanently 
 cemented on. This metal piece is 1 mm. thick. The surface 
 of the glass base is divided into 10 equal parts, thus making 
 the readings between each part 1/10 mm. A broad longitudi- 
 nal etched line passes down the middle of the glass base. The 
 liquid paint to be examined is poured on the base, and the 
 clear glass cover plate placed on the apparatus. The visibil- 
 ity of the longitudinal line disappears at a point between any 
 two of the cross lines, which can be estimated in tenths of a 
 division. The thickness of the paint at the point of hiding 
 may therefore be directly read off in hundredths of a milli- 
 meter. Further experiments are being made to improve the 
 apparatus. 
 
 For determining the relative hiding power of lquid and 
 also dry paint films, the writer has devised a rather simple 
 method which uses a sheet of bond paper upon which squares 
 of black, dark gray, light gray, and other graduated tints of 
 gray are printed with wood blocks. These are lettered from 
 A to H. After the sheets are furnished by the printer, they 
 are kept in stock in the laboratory, and a brush coat of any 
 experimental paint is applied in comparison with a standard 
 product. While possibly subject to criticism from several 
 angles, this method has been found satisfactory for general 
 comparative work. 
 
 Other sheets of paper are printed with blocks of red, blue, 
 green and yellow. They are then sized and varnished to deter- 
 
14 Hiding Power and Brightness 
 ees 
 
 S55 Y . . 
 mine durability of the varnish over various colors. The use 
 of sheet tin in place of paper has been suggested as a base 
 for these test specimens. 
 
 Figure 1 
 
 Shaded paper for comparing Color block paper for varnish 
 hiding power of paints. liquids. 
 
 The Pfund Cry ptometer.—This is an ‘‘absolute’’ instrument 
 by means of which it is possible to determine the hiding — 
 power of a paint and of a pigment. 
 
 Hiding power may be defined as that property of a paint 
 which enables it to obliterate beyond recognition any back- 
 ground upon which it may be spread. Since the color of the 
 background affects the numerical value of the hiding power, a 
 
Hiding Power and Brightness 15 
 
 black background is chosen for white paints and, conversely, 
 a white background for black paints. In the case of colored 
 and gray paints, it will be necessary to carry out measure- 
 ments for both types of background. 
 
 The idea underlying the construction of the cryptometer is 
 this: granting that an infinitely thick layer of paint will hide 
 a given background completely, it 1s sought to find the least 
 thickness of paint which will be as effective in hiding as is the 
 infinitely thick laver. 
 
 The form given the instrument is shown in Fig. 2. Here, A 
 is a plate of black glass 14 x 5 < .6 cm. whose upper surface 
 is optically flat. A transverse groove, B, about 2 mm. deep 
 and 1 cm. wide, is cut in the upper surface and a milimeter 
 scale is etched, as shown in the drawing. Resting upon plate 
 A is plate C (7 X 3.5 X .6 em.), whose lower surface is like- 
 wise optically flat. A strip of thin steel, D, 0.45 mm. thick, is 
 attached to C, so that a wedge-shaped layer of white paint 
 may be formed between the plates. This wedge terminates 
 abruptly at the ‘‘infinitely thick’’ layer, B, and, so long as the 
 hiding is not complete, the line of demarcation is visible. By. 
 sliding the wedge to the left it is finally impossible to see the 
 edge. From a knowledge of the angle of the wedge and the 
 
 - reading on the seale, it is possible to calculate the thickness 
 of this critical layer lying immediately above the edge B. 
 Now, in advancing the plate C until the line of demarcation 
 ean no longer be seen, we have overdone it, so to speak. To 
 correct this, we must reverse the motion of the wedge until 
 the edge can just be distinguished over its entire length. The 
 mean value of the reading corresponding, respectively, to 
 disappearance and appearance of the edge, yields the desired 
 result. Since the fading away and reappearance is so gradual, 
 due to the fact that the least preceptible increment of intensity 
 which the human eye can detect is 1 to 2 per cent (Fechner’s 
 Law), it is clear that no high degree of precision is attainable 
 by this method. By taking ten pairs of readings it is found 
 
 ~that the average deviation from the mean is about 95 per cent. 
 
 The hiding power of a paint may be obtained at once from a 
 knowledge of the wedge-constant A (increase in thickness of 
 paint film per unit linear advance along etched scale) and of 
 l the wedge- reading at complete Rae Lumping together 
 the various numerical constants and recalling that / is meas- 
 
16 Hiding Power and Brightness 
 
 ured in milimeters, it is possible to express the hiding power 
 (H-P) of a paint by the simple relation: 
 40.7 
 
 Hes square feet per gallon. 
 
 Kl 
 A sharp distinction must be made between the hiding power 
 of a pigment and that of a paint. Not only are these quantities 
 expressed in different units, but they are not necessarily 
 related in the sense that a pigment of great hiding power 
 necessarily produces a paint of correspondingly great hiding 
 power. Taking up first the hiding power of pigments, let us 
 
 FIGURE 2 
 
 Diagram of Pfund Cryptometer. 
 
 consider an intimate mixture of x grs. of a white pigment and 
 y grs. of colorless (or very pale) linseed oil. This mixture is 
 tested in the cryptometer and the critical thickness producing 
 complete hiding is found. Let 
 
 ¢t thickness of critical layer (in ems.). 
 
 b—=numbers of grs. of pigment in a disc of 1 em? base and thickness t. 
 Then, if b grs. pigment hide 1 sq. cm., we find the number of 
 sq. cm. A covered and hidden by 1 gr. of pigment from the 
 relation 
 
 ide as Pagina ty | jee 
 b 
 
 Since the hiding power is better the thinner the layer, 1. e., 
 smaller than b, we may define the hiding power of a pigment 
 as the reciprocal of the number of grs. of pigment mixed with 
 colorless linseed oil to painting consistency, which are neces- 
 
 EE 
 
 li alt! 
 
Hiding Power and Brightness 17 
 
 sary to hide a black, non-absorbent area 1 sq. cm. This is 
 numerically equal to the number of square centimeters covered 
 and hidden by 1 gr. of pigment. Hiding powers of pigments 
 will, therefore, be expressed in terms of sq. cm. per gr. The 
 mode of calculating the hiding power of pigment and paint 
 may, perhaps, best be illustrated by means of an actual deter- 
 mination: 
 
 Paint: 
 Basie Carbonate White Lead—72% by wt.—Density 6.81 Specific Vol. 0.147 
 Linseed Oil —28% by wt.—Density 0.92 Specific Vol. 1.08 
 
 Cryptometer constant K — 0.0073 
 Cryptometer reading at complete hiding: 125 mm. 
 
 72 X 147 = 10.6 
 28 X 1.08 = 30.3 
 
 40.9 c.c. paint contain 72 grs. pigment 
 40.9 
 
 —= 0.567 ¢.c. contain 1 gr. pigment 
 (2 
 
 0.567 0.567 
 91.1 area covered by 1 gr. pigment in. cm? 
 Kt 0.0073 x 25 
 
 -°. H-P (pigment) = 31.1 cm? per er. 
 40.7 
 H-P (paint) = 
 
 — 223 sq. ft. per gal. 
 KX1 
 These illustrations will suffice to show how calculations are 
 carried out. A table of hiding powers, determined by this 
 
 method, is presented elsewhere (see page 21). 
 
 Lhe Pfund Colorimeter for Nearly White Surfaces.—In 
 view of the circumstances that ordinary colorimeters are en- 
 tirely too intensive and that visual estimates depend upon the 
 character of the comparison surface, the present instrument 
 was devised to yield quantitative colorimetric data for nearly 
 white surfaces. 
 
 The idea underlying the construction is as follows: If we 
 allow white light to fall upon a surface that is faintly greenish, 
 the light reflected diffusely will contain a slight excess of 
 green; if now this light be allowed to suffer reflection from a 
 second surface, identical with the first, the light thus twice 
 reflected will contain a greater percentage excess of green than 
 before. By allowing, similarly, a third and a fourth reflection 
 to take place, the accentuation of the green tint continues and 
 finally becomes so pronounced that it may be measured readily. 
 
18 Hiding Power and Brightness 
 
 This is the method of ‘‘multiple reflections,’’ according to 
 which only truly non-selective (white or grey) surfaces leave 
 the character of multiple reflected light unmodified. Any 
 outstanding tint, however, is accentuated. 
 
 The apparatus as actually constructed is shown in Fig. 3. 
 Here LZ is a powerful Mazda C lamp which illuminates the 
 outer portion of the circular disk A, whose upper surface is 
 covered with the material to be studied. he light, diffusely 
 reflected, illuminates the lower (similarly coated) surface of 
 
 | 
 
 ---|----4->-------4--0> 
 
 | 
 
 FIGURE 3 
 
 Diagrammatie Representation of Pfund Colorimeter. 
 
 the disk B which, in turn, illuminates the central portion of 
 the disk 4. The light, after multiple reflections, passes: up- 
 ward through a central opening in B and is reflected horizon- 
 tally by means of the photometer cube P. Another beam of 
 light leaving L is reflected from a disk of clear optical glass 
 G, roughly ground on both sides. (Without going into de- 
 tails it may be stated that the most painstaking tests have 
 shown that such a plate reflects visible radiations non-selec- 
 tively.) This light passes through the tube 7 and fills the 
 upper half of the field of view of the photometer cube which 
 has a horizontal line of demarcation and which is viewed 
 through a simple eye-piece yielding a linear magnification of 
 
 See: ee ee eae ee 
 
Hiding Power and Brightness 19 
 
 2.0 The intensity of this beam is varied by rotating the disk 
 G about a horizontal axis. A pointer, attached to the rod 
 bearing disk G, moves over a graduated scale which has been 
 calibrated in terms of coefficients of diffuse reflections. The 
 true values of such coefficients are first determined for a series 
 of grey pastes (zine oxide, glycerine, bone-black) of varying 
 brightness by means of an absolute reflectometer. The colori- 
 meter plates are then covered with these same pastes and 
 scale-readings at photometric balance are recorded. 
 
 As a result of multiple reflections, the difference in scale 
 reading corresponding to surfaces of slightly different bright- 
 ness 1s about four times as great as it would have been had but 
 a single reflection been used. 
 
 While this colorimeter lends itself admirably to the methods 
 of monochromatic colorimetry, it has been found by actual 
 experience that useful results are obtained more simply 
 through the use of color-screens. Accordingly, color screens 
 of dominant hue 480 wu (blue), 540 wu (green) and 605 wu 
 (red) are successively placed in the eye-piece tube at S and 
 psotometric balances are established. The scale-readings thus 
 obtained are then evaluated into reflection coefficients by refer-. 
 ring to the calibration curve. This is essentially a spectro- 
 photometric procedure. 
 
 The final results are presented in the form of curves where 
 abscissx represent wave-lengths of the color-screens and ordi. 
 nates, reflection coefficients. A characteristic series of such 
 curves applying to modern paint pigments will be presented 
 elsewhere (see page 24). 
 
 Hiding Power and Brightness of Pugments.—The writer se- 
 cured from manufacturers, a series of white pigments repre- 
 sentative of those produced in commercial quantities at the 
 present time, and widely used in the industry. Portions of 
 these pigments were rubbed up with glycerine and careful 
 measurements of their brightness made by Pfund with the 
 following result: 
 
20 Hiding Power and Brightness 
 
 TABLE 1.—Brightness of Various Pigments 
 
 Coefficient of Diffuse Re- 
 flection (MgO =99.4%) 
 No. Pigment Pigment in Glycerin 
 
 Blue Green Red 
 A—480uu| A—560 | A—630 
 
 | | | 
 
 1 | Basic Sulfate—White Lead.................. 81.2 87.6 89.3 
 2 | Basic Carbonate—White Lead...............| 79.8 | 82.7 | 4.7 
 3’) Bleetrolytie Winte Lead. Vue 86.4 | 88.0 | 89.0 
 ~ 4 | Old Process Lithopone.@ 2a rn 84.7 | 87.2 | 88.4 
 5 | Leaded Zine (35% Lead Sulfate)......... | 784-1) G00 homueone 
 are Modern Process G. 8. Lithopone..........2.. 87.2 | 87.6 87.8 
 woe Modern Process K. L. Lithopone............. 88.9 | 88.2 88.2 
 “g | Antimonious Oxide. .........1.... 1, ele 86.4 | 89.0 | 90.1 
 aie Titanox (High oil absorption)... 4. 83.1 87.2 89.5 
 Se Titanox (Low oil absorption). 22... .35 sae eeee 86.8 89.0 | 90.1 
 “12, | Zine Oxide (French process)...1.... Aaa 88.2 | 88.9 | 89.5 
 ae aN Oxide (American Process)............... 82.7 86.0 86.8 
 vies Modern Process A. Lithopone................ 88.9 87.8 88.0 
 Ce Modern Process S. Lithopone (Regular)....... 86.6 88.7 89.7 
 ee Madera Procass S. Lithopone (Special)........ a8 48 87.8 87.4 
 oat eMadert Process G. S. Lithopone.....:........ Ses ane Vague 88.0. 
 ae Modern Process A. Bk Label Lithopone....... 88.7 88.0 88.2 
 me Modern Process A. BI Label Lithopone........ 88.7 ee pp 4 
 ee Modern Process P. L. R. Lithopone........... 80.5 | 88.4 | 87.8 
 
 Se ean eee cl n eee oe Set ae a BE 
 
Hiding Power and Brightness 21 
 
 TABLE 2.—Hiding Power of Pigment-Oil Mixtures, Each Containing 50 Per Cent 
 Pigment and 50 Per Cent Linseed Oil by Weight 
 
 Paint Pigment Hiding Power 
 No. Sq. Ft. per Gal. 
 1 mpsie cuipnate--White Lead.................2 0.005. 116 
 a Basic Carbonate—White Lead...................... eg ate 
 3 Retr VO VV LG LOA). eke cee eee ee 
 aa Old Process arohe. 6 it cg ey mt ee 145 Baer 
 ae Teaded Zinc (55% Lead Sulphate)...........:....... hh O00 as 
 6 Modern Process G. 8. Lithopone is Beer een eae) sian Ailes 0G 
 7 Modern Process K. L. Sa ee See NE dee ue Boon ape 
 8 Antimonious Oxide........ ee is Seer ie ee theres ee 193 Ms 
 0%. Titanox (High oil ee Be REE rd cra iG Suter ee oS ae 
 11 Titanox (Low oil absorption). . See cle es DARN oe 
 {2 aMe Oxide feTiGl PTOCeSS) 6... ke oe cee ee Ny sons 
 ‘ 13 mimew) side (American process) .... 2.0.0.0. 00. 5.0000 e een ne 
 14 Modern Process A. Lithopone............. Oe ees. 55200 Pie 
 
 Another series of these pigments was ground in a mill with 
 refined linseed oil, on the basis of 50 parts by weight of pig- 
 ment to 50 parts by weight of oil. These gave the following 
 hiding power results in the writer’s laboratory. See Table 2. 
 
 FOOTNOTE: 
 Tests with the Pfund cryptometer on a large number of samples of each pigment examined by 
 R. L. Hallett gave average general results as follows: 
 
 Hiding Power of White Pigments 
 
 For complete hiding: 
 
 Sq. cm. Sao tn Lbs. per | Hid. Pow. | Hid. Pow. Tint. 
 
 per gram per lb. 100 sq. ft. weight volume Power 
 ELE MUCACAt. wits diced sss + 40 19.5 Leal 100 100 100 
 Basic lead sulphate......... 30 Wate 6.8 75 1 85 
 "PTET WOE. Ag aga a 80 39.0 2.6 200 128 350 
 Zine oxide(American process) 46 92.4 4.5 116 96 170 
 NHI GWOMG 8p clecivis isis sincere. ee 50 24.4 4.1 125 80 200 
 
 It should be pointed out, however, that pigments of great 
 brilliancy, such as zinc oxide and basic sulphate-white lead, 
 
22 Hiding Power and Brightness 
 a 
 may show relatively low hiding power in their untinted condi- 4 
 tion. When slightly tinted with colors to match the color of 
 leaded zinc or basic carbonate-white lead, they may show as 
 great or even greater hiding power than such pigments.* 
 Hiding power and brilliancy should, therefore, always be con- 
 sidered together. 
 
 A third series was ground, using only sufficient oil to give 
 consistency for brushing. The readings on the cryptometer 
 are shown in table. 
 
 G A R 
 
 a 
 § 
 w 
 3 
 
 & $ 
 
 7 
 
 ) 
 o 
 1°) 
 
 | 
 
 Reflection Coefficient (Brightness ) 
 @ 
 w 
 
 © Untinted 
 © Blacked 
 @Blued 
 
 | 
 ‘650 
 
 G R 
 Wave-Lengths 
 
 | 
 
 © 
 wo 
 wn 
 ° 
 
 FIGURE 4 
 Curves showing the effect of adding Carbon Black and Ultra- 
 
 marine Blue to French Process Zine Oxide ground in refined 
 Linseed Oil. 
 
 * See J. Franklin Inst., Nov. 1919, p. 679. Also J. A. Calbeck’s paper, “An 
 Application of the Pfund Cryptometer,” etce., Proc. Amer. Soe, Test. Mater., 
 1922. 
 
Hiding Power and Brightness 
 
 23 
 
 TABLE 3.—Hiding Power of Pigment-Oil Mixtures Containing Different 
 
 Paint 
 
 13 
 
 14 
 
 Amounts of Oil 
 
 Percentage By Hiding Power 
 Weight As 
 Determined By |_____ ie es 
 Pigment Analysis 
 hn, Se ee Pigment Paint 
 Sq. Cm. per Gr.) Sq. Ft. per Gal. 
 Pigment} Oil 
 Basic Sulphate White 
 Lalor ha tee a a 69.7 30.3 25 159 
 Basic Carbonate White Le s ae 
 Neer Oe iy 70.4 29.6 36 242 
 Electrolytic White ee, ee 
 Or CS ee iieo 28.7 32 212 
 Old Process Lithopone | 58.4 41.6 59 ZZ 
 Leaded Zinc (85% Lead a a 
 i be] N20 or ee hae aaa 63.6 36.4 49 252 
 Modern Process G. 8. ms a 
 PEMOPONG Se... | 61.6 38 .4 57 252 
 Modern Process K. L. ae 
 He HOPONE Aa Ss. - 58.4 41.6 58 eon 
 Antimonious Oxide...) 64.5 35.5 44 232 ae 
 Titanox (High oil ab- 
 BORDEN) 6 55.2. 1. 60.1 39.9 69 293 
 Titanox (Low oil ab- 
 OED RON) cen W506. x0" 66.3 33.7 OF 293 
 Zinc Oxide, French 
 POCCHS das ss. > 50.2 49.8 A4 142 
 Zine Oxide, American 
 Procesgries. fee. 46.4 53.6 bo 155 
 Modern Process A. 
 bithopone ...2.,.:. 59.1 40.9 54 212 
 
 * Note low luminosity of -this sample in Table 1 which acounts for greater 
 hiding power as compared to other lead. 
 
24 Hiding Power and Brightness 
 
 ee w 
 °o 
 o 
 wn 
 nn 
 
 3 
 WINE 
 
 ANAT 
 SEER 
 
 = 
 \S 
 » 
 
 i 
 MK 
 
 | 
 . 
 
 aa 
 ; 
 M 
 
 wai 
 aii 
 Nt 
 
 uw 
 4) 
 | 
 
 N 
 NI 
 
 Reflection Coefficient (Brightness) 
 
 KAW 
 
 ye 
 
 B G 
 Wave-Lengths 
 
 22) 
 2) 
 
 o 
 on 
 oO 
 
 FIGURE 5 
 
 Curves showing the brightness of commercial opaque pig- 
 ments ground in glycerine. Degree of whiteness is indicated 
 by the approach to a straight horizontal line. 
 
 Hallett Hiding Meter.—An apparatus devised by R. L. 
 Hallett for measuring the hiding power of dry films of paint 
 was originally described in the 1920 Proceedings of the Amer- 
 ican Society for Testing Materials. It has been used in Hal- 
 lett’s laboratory for several years, with apparently satisfac- 
 tory results. A brief description of the apparatus is given 
 below, but the original communication should be read for a 
 detailed description. The instrument can be modified for 
 use upon different parts of a painted surface, and variations 
 in hiding power over knots and dark spots in lumber ean be 
 determined. 
 
Hiding Power and Brightness 25 
 a A 
 ‘“The instrument is shown in Fig. 6, and consists of a 
 regular microscopic frame with a long tube fitted with a plain 
 ground-glass objective, and having simply a small circular 
 opening for the ocular. The principles involved are not new, 
 but the application seems to be novel, as we do not know of 
 these principles having been previously used for this purpose. 
 If a piece of ground glass, or other more or less transparent 
 material which has the property of highly diffusing or dispers- 
 ing the rays of light which pass through it, be placed in direct 
 contact with a surface having two colors or two shades of the 
 same color, and if the surface be viewed through the glass, 
 the two colored portions and the line between them will be 
 perfectly clear and distinct. We have found that as the 
 ground glass is withdrawn from the surface, the line between 
 the colored portions immediately becomes blurred and indis- 
 tinct, and the colored portions themselves also become blurred 
 and tend to blend into each other. This effect is increased as 
 the ground glass is further withdrawn until a point is reached 
 where the entire field becomes blurred and blended, so that it 
 appears to be of uniform color, and there is no distinction 
 between the two colored portions. | 
 
 FIGURE 6 
 
 Hallett Hiding Power Meter. 
 
26 Hiding Power and Brightness 
 
 ‘“We have also found that if one of the colors be partially 
 obscured, as by having applied over it a semi-opaque coat of a 
 paint of the other color, and the contact and withdrawal of the 
 eround glass be repeated, the two colored portions of the field 
 will blend and the field will appear to become uniform when 
 the ground glass is withdrawn to a much shorter distance 
 from the surface than was the case where the full original 
 colors were used. The application of the coat of paint over 
 the surface partially hides the portion of the surface which 
 is not the same color as the paint, and the degree of hiding 
 may be measured by the distance through which the ground 
 glass must be withdrawn to blend the field. The portion of the 
 surface which has the same color as the paint of course re- 
 mains unchanged in color and offers the same basis for com- 
 parison. The decrease in sharpness of the image and the 
 blending of the field, as the ground glass is withdrawn, is due 
 to the diffusion of the light. The colored surfaces diffuse 
 the light equally in all directions, but when the ground glass 
 is in contact with the surface, the diffusion takes place above 
 the glass and the eye sees the two colored portions distinctly. 
 As the ground glass is removed further and further from the ~ 
 surface, the diffused rays from the two colored portions of the 
 surface spread in all directions so that the rays from each 
 color tend to mingle with those from the other color and strike 
 the ground glass mixed together. This results in a gradual — 
 blending of the two colors over the entire field. The ground ~ 
 glass finally reaches a point where the field seems to become ~ 
 blended into one uniform color. As the blending is dependent — 
 on the diffusion of the rays, it must be proportional to the — 
 square of the distance between the ground glass and the sur- — 
 face viewed, as diffusion varies directly with the square of © 
 the distance. Theoretically, there would never be a perfect — 
 blend, as each part of the field would always transmit to the 
 eye more rays of its original color than of the color of the — 
 adjacent part whose rays are diffused on to it. It is, there- — 
 fore, apparent that the theoretical distance at which the field 
 would become perfectly blended, would be infinity.’’ | 
 
Hiding Power and Brightness 27 
 
 Working with a number of white pigments ground in linseed 
 oil upon the volume basis, some interesting results were ob- 
 tained by Hallett, as shown below. 
 
 PIGMENT. Hipine Power, 
 RE ire tee ae yee ee cli eek SEO erie 100 
 BM AL eos oon Sei ceva ove cicccn...., 82 
 SL A 167 
 EE ee. ns 2 oo ook eve van eee. eee 103 
 as org oy Ss sole es de hho bec Oune cece ce, 85 
 eISSN 1 
 TS Rn 5 
 ONS os a 
 OE Re 4 
 ee de soe oe eee Ohne heen. 1 
 
 White lead was taken as the standard and arbitrarily given 
 a hiding power of 100. 
 
 Tinting Power vs. Hiding Power.—In a subsequent paper 
 entitled ‘“The Hiding Power of Pigments,’’* Hallett gives the 
 following table: 
 
 TABLE 4 
 RELATIVE RELATIVE RELATIVE 
 HIDING HIDING HIDING HIDING TINTING 
 POWER, POWER, POWER, POWER, POWER, 
 
 SQ. FT. SQ. CM. WEIGHT VOLUME WEIGHT 
 PIGMENT PER LB. PER G. BASIS BASIS BASIS 
 No. 1. Carbonate White Lead.. 20 40 100 100 100 
 No: 2. Basic Lead Sulfate...... 15 30 fee eee 85 
 Os SILATIOX. sc... ss os Peevs ki 40 80 200 128 350 
 eee ISIIO  .. se te c e s 2s 46 195 96 170 
 arr LAtMOpoOnes.... 0.0. ..5. 25 50 125 SO 200 
 
 He states that the tinting power and hiding power of pig- 
 ments are directly related, and that the hiding power is 
 directly proportional to the tinting power for pigments which 
 have the same color and brightness. In this connection, there 
 is presented on page 303 the method adopted for determining 
 the tinting power of pigments by L. E. Barton, together with 
 a table. 
 
 Martens Photometer for Hiding Tests.;—This is an in- 
 strument which measures the contrast in brightness offered 
 by two portions of a field of view. If a light colored paint be 
 spread upon a background which is divided into a white por- 
 tion and a black portion, there is a certain thickness at which 
 the differential brightness of the background is eliminated. 
 This may be called the hiding thickness. Ina determination, 
 a background divided into a white and a black portion is 
 
 *A.S.T.M., Vol. 26, Part II, 1926. 
 TH. D. Bruce, Tech. Paper, No. 306, U. S. Bur. of Standards. 
 
28 Hiding Power and Brightness 
 ee ci es 
 coated with the paint, and when dry is placed with the divid- 
 ing line in the field of view. On looking into the photometer, 
 a diviiea field is seen. The two halves of the field are matched 
 by rotating a Nicol prism and their relative brightness caleu- 
 lated as a function of the angles of rotation. The apparatus 
 is shown in Fig. 7 
 
 The contrast ratio of the two halves of the field is first 
 calculated from the angles of rotation mentioned above. ‘Then, 
 by means of the equation 
 
 L 
 H.T. = va|— cae! 
 b 
 
 where a is the thickness of the film under observation and b 
 the contrast ratio, H.T. the thickness of film necessary to make 
 the black side of the plate 98 per cent. as bright as the white 
 side, is determined. 
 
 These hiding thickness values are the thicknesses of the 
 dried film that will be required to hid ‘‘completely.’’ From 
 these values, the hiding powers in square feet per gallon may 
 be obtained, provided a knowledge of the volume percentage 
 of the non- volatile portion is known. This may be calculated 
 from the specific gravity of the paint, specifie gravity of the 
 volatile constituent, and the weight percentage of volatile con- 
 stituent. For example, the following illustration is given: 
 
 a—sp. gr. of paint —1.48 
 
 b=sp. gr. of volatile constituent (turpentine) = 0.867 
 
 c—wt. percentage of volatile constituent in paint =10 
 
 xX volume percentage of volatile constituent in paint 
 H.T. = hiding thickness = 0.0706 mm. 
 
 ac 
 SS eee 
 b 
 100 — X = 100 — 16.8 = 83.2% non-volatile by volume 
 Then the hiding power (H.P.) in square feet per gallon 
 may be read from Table I in Technologie Paper No. 306, or 
 calculated from the formula: 
 
 0.4075 (volume per cent of non-volatile) 
 H.T. 
 
 HP. = 
 0.4075 x 88.2 
 ae eo TOS 
 
 —= 480 sq. ft. per 1 gallon 
 
 Hiding Power Comparisons.—There is given below some 
 hiding power readings expressed in square feet per gallon 
 as determined (in May 1927) upon a number of paints with 
 
Hiding Power and Brightness 29 
 
 FIGURE 7 
 Apparatus for Measuring the Hiding Power of Paints. 
 
 The upper telescopic portion is the Martens photometer, while the lower 
 spherical shaped portion is the illumination chamber designed and built at 
 the U. S. Bureau of Standards. 
 
 NOTE—For full construction and theory of the Marten’s photometer, 
 consult the original paper by Marten’s. Physikal Zeitschrift (Leipzig) i, p. 
 299; 1900. 
 
 the Pfund Cryptometer and with the Martens Photometer. It 
 will be noted that the results on the Pfund Cryptometer are 
 usually somewhat higher than those obtained upon the other 
 type of instrument. Since the use of the Pfund Cryptometer 
 is extremely simple and rapid, this instrument has been pre- 
 ferred for the determination of hiding power at this labora- 
 tory. 
 
30 Hiding Power and Brightness 
 
 Hiding Power on Hiding Power (Bur. of 
 Pfund Cryptometer, Standards Method) 
 
 FORMULA sq. ft. per gal. to sq. ft. per gal. to 
 hide a black surface hide black surface 
 A. Pure Titanium 
 Oxide 100 55,5 480 
 B. Calcium Titanox 100 339 408 
 C, Barium Titanox 100 339 322 
 Dw “Ditanox 80 
 Zinc Oxide 20 305 234 
 BE. Trtanox 70 
 Zinc Oxide 30 290 208 
 FEF. Titanox 50 
 Zinc Oxide 50 ZTE 200 
 G. Titanox 80 
 Corroded Lead 20 290 B&W 
 H..- Titanor 60 3 
 Corroded Lead 20 265 223 
 Zinc Oxide 20 
 
 Formula A has 50% Pigment and 50% Liquid. Formulas B to M all 
 have 60 pigment and 40 liquid. The liquid in each is the same, namely, raw 
 linseed oil 60%, heavy bodied oil 20%, turpentine and drier 20%. 
 
 Hiding Power on Hiding Power (Bur. of 
 
 Pfund Cryptometer, Standards Method) 
 FORMULA sq. ft. per gal. to sq. ft. per gal. to 
 hide a black surface hide black surface 
 To. (LItanox 50 
 Corroded Lead 20 Tees 188 
 Zinc Oxide 30 
 Ke Seo 30 
 Corroded Lead 20 244 180 
 Zinc Oxide 50 
 L. Lehigh Leaded Zinc 70 259 141 
 Lithopone 30 
 M. Lehigh Leaded Zinc 70 305 207 
 Titanox 30 “3 
 
 AA. Tung Oil Spar Varnish 
 containing 40% Pure 
 Titanium Oxide 382 346 
 
 BB. Tung Oil Spar Varnish 
 containing 40% Bar- 
 ium Titanox 234 yids 
 
 CC. Tung Oil Spar Varnish 
 containing 40% Cal- 
 cium Titanox 254 208 
 
 DD. Tung Oil Spar Varnish 
 
 containing 40% Litho- 
 
 pone 174 147 
 EE. Tung Oil Spar Varnish 
 
 containing 40% Basic 
 Carbonate White Lead 122 84 
 
CHAPTER II 
 “CONSISTENCY 
 VISCOSITY—PLASTICITY—MOBPILITY 
 
 In this chapter methods are presented for determining the 
 consistency of oils, varnishes, paints, lacquers and similar 
 products. There is also included a brief description of differ- 
 ent types of apparatus used, and tables for the conversion 
 of the readings of one type of instrument to another. In 
 order to understand what is meant by the various terms em- 
 ployed in this chapter, the following definitions are given: 
 
 (a) The consistency of a product is its resistance to defor- 
 mation or flow. This resistance may be due to viscosity or to 
 plasticity. 
 
 (b) The viscosity of a product is its resistance to deforma- 
 tion or flow when deformation or flow is directly proportional 
 to the force exerted at all times. 
 
 For example, if a tube tapered at one end to a small orifice 
 is filled with varnish, we note that no matter what the con- 
 sistency of the varnish may be, it will flow from the tube, with- 
 out any regard to the hydrostatic head or any other factor of » 
 pressure. | 
 
 (c) The plasticity of a product is its resistance to deforma- 
 tion or flow when a certain initial finite force is necessary to 
 overcome the internal friction and cause the product to flow. 
 
 For example, if the same tube is filled with a heavily pig- 
 -mented paint, such as an interior flat white, and if the hydro- 
 static head of the paint becomes very low the paint will not 
 flow out of the orifice. The pressure has fallen below the 
 initial pressure required to cause a plastic substance to flow. 
 This initial pressure is called by some authors the ‘‘yield 
 value.’’ 
 
 (d) A substance is said to have a viscosity of one poise 
 when a force of one dyne is required to move a surface of one 
 square em. at the speed of one centimeter per second, relative 
 to another plane surface separated from it by a layer one 
 centimeter thick. The poise is the measurement of absolute 
 viscosity. 
 
 Instruments for Measuring Viscosity—All viscometers in 
 use may be classed under the four following types of: air 
 bubble—falling weight—torsion—or efflux. 
 
2 Consistency 
 
 (1) Air Bubble Type (Gardner-Holdt Standards ).—Small : 
 
 vials or tubes closed at one end and standardized as to internal 
 dimensions, are filled with a liquid, the absolute viscosity of 
 
 which has previously been determined, and a cork inserted ~ 
 
 so as to leave a small air space. A number of these liquids 
 of varying viscosity are put up this way and comprise a set. 
 When the tubes are inverted, the times required for the bub- 
 
 bles to arise are directly proportional to the viscosities of the ~ 
 
 liquids in the tubes. 
 
 In a determination of viscosity, an empty standardized tube 
 is filled with the material to be tested, and the air space ad- 
 justed to the size in the comparison tubes. The rise of the 
 bubble in the tube is then compared with ete on the standard 
 set* 
 
 Below are given the data from the Gardner-Holdt Vis- 
 cometer tables, describing the method of use and giving the 
 range of viscosity in poises: 
 
 Before making the test a tube containing a sample of the 
 varnish to be tested and the case of standard tubes should be 
 placed together for a sufficient period to bring them to the 
 same temperature. The test should preferably be made at 
 25° C. (77° F.) on account of the difference in the temperature 
 coefficients of viscosity of mineral oils and of varnish. 
 
 The air bubble in the sample tube should be approximately 
 the same size as that in the standard tubes. When operating 
 the standards, the case should be held in an upright position 
 with the red sealed corks at the bottom, so that the bubbles 
 
 will be at the glass end. The case should then be inverted — 
 quickly and the sample compared to locate the standard tube ~ 
 
 giving approximately the same bubble test. 
 
 The standard tubes and the empty tubes supplied with this . 
 case have an approximate inside diameter of 10.75 mm. It is ~ 
 very important that these tubes should be of very nearly the 3 
 
 same diameter, the allowable variation being about .1 mm. 
 Tubes not in accordance with this specification cannot be used. 
 
 *In measuring viscosity of varnishes with Gardner-Holdt tubes, Gregory — 
 has used the standard tubes firmly fastened in a holding rack, with sufficient — 
 space between the tubes for test samples. By the use of this holding rack — 
 the tubes are subject to less breakage and gumming up with varnish, and any ~ 
 
 variations in temperature effects due to the handling of the tubes is elimi- 
 
 nated. The rack is supported on a solid foundation and the whole set can be — 
 
 inverted at once. 
 
A a O00) 
 A 0.65 
 MEER Sects: 4x 0.85 
 Me Feta! «sh 1.00 
 1D) » 1.25 
 
 K 
 
 Consistency 
 a 
 
 There is given below the approximate absolute viscosities of 
 the liquids used in the standard tubes: 
 
 FIGURE § 
 
 .. 1.40 eA Seen 
 pea s SE Mk OD Li Whee twists 3's 
 Mates ees ee OO dC ae ee 
 ane 2.25 INGe ap esa hate 
 BRO tuning AAEM) PAP es cee Gila 
 
 Doolittle Viscometer. 
 
 af 
 
 Lies I.) 
 .. 4.00 
 .. 4.35 
 ieee els eck 
 Piemintiwiete NU) 
 
 . 0.00 
 
34 Consistency 
 Oe ee 
 
 (2) Falling Weight Type—Viscosity is sometimes meas- 
 ured by dropping a steel ball in a vessel containing the fluid 
 and timing the fall between two elevations. This method prob- 
 ably gives a fairly accurate measure of viscosity for very vis- 
 cous liquids. It is used to a great extent in the lacquer indus- 
 try. When a nitro-cotton is referred to as a % second nitro- 
 cotton, it is meant that when the cotton is made up in solution 
 according to a given formula, the ball required 2 second to 
 fall through 10 em. of the solution. 
 
 (3) Torsion Type——In instruments of this type a pendu- 
 lum is used to measure viscous resistance. The instruments 
 consist essentially of a cup containing the fluid, the viscosity 
 of which is to be measured, and a cylinder which is suspended 
 in the fluid. In some viscometers, such as the Doolittle, a 
 cylinder is rotated in the fluid. The Stormer viscometer 1s 
 also of this type. In others, such as the MacMichael, the cup 
 containing the fluid is rotated and the viscosity measured by 
 noting the angular distance through which a dise is carried 
 by the fluid. 
 
 (4) Efflux Type—A great variety of instruments of this 
 type are inuse. In its simplest form, an efflux type viscometer 
 may consist of a pipette or tube holding a definite quantity of 
 liquid; the time required for a given volume to flow out at a 
 certain temperature being taken as a measure of the viscosity. 
 In most instruments of this class, the liquid flows out under 
 its own weight. In several, air pressure is used to produce 
 flow. A few of the instruments of this type are the Saybolt 
 (U. S. Standard); Redwood (English Standard); Engler 
 (German Standard) ; and the Herschel Burette Consistometer. 
 These instruments are not as adaptable to the paint and 
 varnish trade as to the petroleum industry in which they are 
 used widely. 
 
 G. E. Cup for Viscosity—tThe writer’s attention has been 
 called to a simple form of instrument used by one varnish 
 manufacturer to determime the body of his products. This 
 apparatus, which is shown ‘in Fig. 9, consists of a brass cyl- 
 inder 17.8 cm. in length and*2.8 cm. in diameter. One-half 
 em. from the top is an engraved line up to which it is filled 
 with the product. To the bottom of the cylinder is screwed ~ 
 a conical shaped nozzle. This has a top diameter similar to — 
 that of the cylinder, but it tapers down to an orifice .8 em. in — 
 
| Consistency 30 
 _ re senses 
 VISCOSITY CONVERSION TABLE 
 
 Approximate values of viscosity by other instruments as compared to the 
 Gardner-Holt Standards 
 
 Gardner Say bolt 
 Gardner-Holdt Stds. Mobilometer Engler. Redwood. Universal. 
 eS 74 gr. load Degrees Time in Time in 
 Letter Poises Giconic: Seconds Seconds 
 A 0.50 4.8 8.1 250 285 
 B 0.65 6.3 10.0 300 345 
 € 0.85 8.4 Lo27 420 me 4/0 
 D 1.00 9.2 16.2 490 550 
 E 1,25 12.0 20.0 610 690 
 F 1.40 12.5 2055 685 770 
 G £05 15.9 26.5 800 910 
 H 2.00 16.9 32.4 990) es, 1120 
 nf pee Rs) 20.0 30.3 1110 1250 
 J 2.50 22.1 40.5 1230 1390 
 K Jil fs 24.9 44.1 1350 1570 
 L 3.00 25.9 48.1 1450 1650 
 M 3.20 29.9 Sit 1560 1770 
 N 3.40 33.0 55.4 1690 1900 
 O 3.70 34.3 59.5 1800 2040 
 IP 4.00 eb 63.2 1950 2190 
 QO 4.35 41.3 69.6 2110 2390 
 R 4.70 42.3 i 5.9 2280 2590 
 S 5.00 47.3 80.0 2430 2740 
 a 5.50 50.0 92.0 2800 3160 
 
 length and 3.5 mm. in diameter. The time is taken for the. 
 product to flow from the engraved line out of the orifice. This 
 apparatus is referred to as the G. E. Cup and is in the class 
 of instruments where but one pressure is obtainable, namely, 
 the hydrostatic head of the product which is being run. In 
 the case of a truly viscous product such as varnish, this cup 
 will give a value and a conversion constant may be obtained 
 from this value for any specific load that is being used on the 
 Gardner-Parks Mobilometer. When a plastic product such 
 as an exterior pigmented oil paint is run in the G. E. Cup, 
 no conversion factor can be established between the reading 
 obtained and the reading obtained with the Gardner-Parks 
 Mobilometer for any specific weight that is apphed. Upon 
 running a plastic product in the G. E. Cup some of the ma- 
 terial will remain in the cup adhering to the walls. This is 
 caused by the fact that these products are often so plastic 
 that they will not flow, the hydrostatic head having fallen 
 below the yield value of the product. Since various paints 
 have different degrees of plasticity and hence different yield 
 values, the amount of paint that would remain in the cup would 
 vary, the density not being proportional to the yield value. 
 
36 Consistency 
 
 FIGuRE 9 
 
 For this reason, no conversion constant could be obtained 
 between the readings on the Gardner-Parks Mobilometer and 
 the readings obtained on the G. E. Cup for plastic paint prod- 
 
Consistency 37 
 een 
 ucts. It is understood, however, that this type of cup has 
 proved satisfactory for factory use in gauging the body of 
 elear varnishes and clear lacquers and on products of low 
 pigmentation. 
 
 Below are given a few readings obtained with the G. E. Cup 
 as compared with those obtained by the Gardner-Parks 
 Mobilometer when the latter instrument was run with a brass 
 plunger, a perforated brass dise attached and a weight pan, 
 these having a combined weight of 74 grams. No additional 
 load was applied to the weight pan. Constant temperature 
 was maintained throughout and the products were run in one 
 type of apparatus and then directly in the other. Lubricating 
 oils of non-changing viscosity were used. | 
 
 G. E. Cup Seconds 
 
 esialemeter Seconds Constant 
 
 _ Viscous Propucts 
 Mobilometer G. E. Cup Conversion 
 
 Seconds Seconds Constant 
 (no load) 
 a 2 1.4 29 pais 
 es ew ke 5.4 tot 24. 
 OU Uy et Se a 6.6 152 23 
 G0) een 27.) 520 Zo 
 
 Puastic Propucts 
 Mobilometer' G. E. Cup Factor 
 
 ae (no load) 
 Flat White Paint ... Dei 99 aya) 
 Flat White Paint .... 9.4 40 4.3 
 Peterior Gloss ...... BAO 66 Hi, 
 Exterior SST eOt Ge 3. ci. 22-0) AAS oo 
 
 It will be noted that no constant factor could be obtained 
 with the plastic products, while a factor constant within the 
 limits of experimental error was obtained with viscous oils. 
 
 CoNSISTOMETERS 
 
 This class of instrument is designed to cover the entire 
 field of consistency from a very low viscosity to a high plas- 
 ticity. The Bingham-Green Plastometer is an apparatus in 
 which the pressure is variable and almost any substance which 
 exhibits a flow may be run upon it. Because of certain appar- 
 
38 Consistency 
 
 ent limitations and high cost, the industrial application of 
 this plastometer in the paint industry has been slow. 
 
 In a most interesting article entitled ‘‘Some Factors which 
 Affect the Plasticity of a Paint,’’* E. C. Bingham and A. G. 
 Yates describe the result obtained in grinding certain pig- 
 ments in various proportions in oil for different periods of 
 time in a ball mill. The measurements for yield value and mo- 
 bility were made on a plastometer. Important results were ob- 
 tained, such as the yield value being independent of the effect 
 of the fluidity of the oil; the mobility of certain mixtures 
 being but little affected by the size of pigment particles, ete. 
 Some of the important conclusions made by Bingham and 
 Yates are as follows: 
 
 1—As the grinding of a pigment in oil progresses, the yield 
 value at first decreases, but after 30 hours becomes constant. 
 The mobility under the same conditions at first increases, 
 passes through a maximum, and then decreases more and more 
 rapidly. The maximum occurs after about 30 hours in these 
 experiments. 
 
 3—Silica and lithopone have very different plasticities at the 
 same weight concentration. When. they are compared at 
 equivalent volume percentages, however, the mobilities are 
 nearly the same and the yield values are not very different. 
 This fact is the more striking since the particle size in the two 
 pigments is so different. 
 
 4—Comparing blown oil with acid-refined linseed oil at the 
 same concentration of pigment, the effect of the fluidity of 
 the medium is shown. The mobility falls off in presumably 
 the same ratio as the fluidities of the oil, but the yield value 
 is independent of the fluidity of the oil. 
 
 5—Polar colloids—as, for example, aluminum stearate—have 
 very slight influence on the mobility, but they have an extraor- 
 dinary effect in raising the yield value. 
 
 7—Moisture exerts a prodigious effect on the plasticity of 
 paint, 0.5 per cent of moisture raising the yield value from 90 
 to 3450, and at the same time reducing the mobility to one- 
 fourth of its former value. 
 
 8—QOxidation and polymerization affect the fluidity of an oil, 
 so we should expect the mobility to be affected. It was thought 
 
 * J. Ind. & Engrg. Chem., Oct. 1923, p. 1033. 
 
 a ee Te eS a eee ee eT ee Ee. ae Vern 
 
Consistency 39 
 
 that the fall in the mobility on long grinding might be attribut- 
 able to one of these causes, but grinding in an atmosphere of 
 nitrogen only prevented it, partially. A paint ground in an 
 atmosphere of carbon dioxide has a yield value three times as 
 high as when ground in the air. 
 
 Gardner-Parks Mobilometer.—This instrument is a consisto- 
 meter built to meet the needs of the paint and varnish indus- 
 try. It is of low cost, covers a very wide field of consistency, 
 may be run with clear or opaque substances and is built of 
 a material which will stand factory usage. It is very simple 
 to operate and a number of determinations may be run in a 
 very short time. The instrument consists of a brass cylinder 
 which may be removed and easily cleaned, a plunger which 
 fits into the brass cylinder and which is allowed to fall through 
 20 em. of the product. 
 
 Method of Use-—Temperature must be taken into considera- 
 tion just as with instruments for the measurement of viscosity. 
 Provided the room temperature is approximately 20° C. (68° 
 F’.), the paint or other products used will not change in tem- 
 
 FIGURE 10 
 
 Mobilometer. 
 
 perature in the short time required to make the tests. It is 
 suggested, therefore, that measurements be made at approxi- 
 
40 Consistency 
 
 mately 20° C. (68° F.). .The cylinder is filled with material - 
 to the mark. The plunger to be used is inserted and forced to 
 the bottom. .A mark is made upon the rod at the top of the 
 bracket when the plunger is at the bottom of the eylinder. 
 Another mark is made 20 em. below the first mark. The 
 plunger is then raised so that the second line coincides with 
 the top of the bracket, care being taken to make sure that the 
 dise at the end of the plunger is covered with paint. A weight 
 is applied to the pan on top of the plunger and the time im 
 seconds for the first line on the rod to coincide with the 
 bracket. determined with a stop watch. If desired, the pro- 
 cedure may be repeated with a number of different weights 
 and the points plotted on a curve. This instrument has been 
 used to determine the consistency of a large number of paints, 
 enamels, and lacquer products. Some of the results are 
 presented below as Tables 5 and 6. The automobile lacquers 
 represent a viscuous type of material and when the data are 
 plotted the curves are straight lines. The heavily pigmented 
 interior flat white wall paints represent a plastie type of 
 material and the curves are not entirely straight lines. 
 
41 
 
 Consistency 
 
 080° scl S&T" GL 160° Ort 680° 0°CT 
 690° ovt LLO O'eT Gol 08 L80° a2 vLO Ser 
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 990° 0O°sT S90: pid | G60" Sor G90 SSE yS0° ost 
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 660" SSP 960° 0°6¢ LvO SIc 860° 0°9¢ ¥c0° ie 
 610° OES anew 5 i ies bea | ez". res 020° C'6F 
 STO 0°29 810° cys c&0 OTe 610° S°cs 910° 0°19 
 I10° > Cz" 0°0F CTO" 0°89 eT()" COZ 
 eg ety se eee t 9600° Oro! 610° Sees O10" 0°86 600° 0°Sor 
 109044 199 spuorag = 19904 199 spuorag —- 10904 199 spuorag wo0ddiaye = Spuovas, ss p90Ad1vay = SpuoIas 
 P2d@, HAMM Cd kDa) WW Aidt: bal 46 Bee) A 
 Go SN b ON SN CaN PON 
 
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 SUMNDOVT ATIGOWOLAY 
 
 G QIAVL 
 
 Gos 
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 14513 
 
ee ee eee ae 1 ee ag on Ce eve: ee ne eae or eee FS eae . 
 
 Consistency 
 
 42 
 
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 PFO’ «O'fZ L000’ O'€67T $90" SST 8h0 OTT 190° OST 02 os MOTS S°7CT MOTS GLI 
 
 dAOW dAOW dAOW 
 ¥c0 OTP JON §90° O'6T 680 O97 O0S0 0°02 Stiga es JON MOIS JON = OST 
 TEM THEM TIEM 
 sAOW dAOW sAOW dAOW 
 VIO’ OL JON 680° 0°9% 620° SHE FEO SG'6~ Or oor ION JON JON Gol 
 TTEM THEM TTEM THEM 
 dAOW dAOW dAONW DAO J 
 L00° O°EST ION 820 Sse 120° SLb 120° SLP £90 OOF JON JON JON 00T 
 TTTM THEA THEM THEM 
 DAO dAOW dAOWL DAO 
 MO[S AOIS JON LI10° S°8S 10° O'SZ FIO 0°96 TED OE ION JON JON GL 
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 pandd y 
 6 ON § ON LON 2 ON Guth b ON Peen € ON Fe One 14318 
 
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 SINIVd TIVM LVI 
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Consistency 43 
 
 Comparing Mobilometer and Viscometer Readings.—The 
 two types of instruments for measuring consistency, used in 
 a be oratory, and to which most attention has been paid 
 
 eee 
 
 0 
 ] 
 
 ] peoys®2 QQ|4O4quty 
 
 5 ete Sia No 
 ack 
 
 S 
 
 Pk 
 00 
 a P 
 
 Ce) 
 
 g 9 
 SPu0d2®S O9 GS OS Sv Or GE CE G2 O02 SI Ol GS PeOjONYoJewly 
 
 \ 
 
 ea 
 Bes 
 NE 
 we aN es 
 IN 
 
 eles Wee ee alae eal 
 eee ene 
 
 lal es Seon el aes ee 
 
 a le ©) NS, aay © en? | Bae Gia 4 boca 3 hae A Maid | las ©. Wag 
 
 AGE cea 
 [eS NG es 
 ts | ian a 
 
 Smee eS 
 a tae ee 
 
 EA Goee 
 (aN 
 | SSR Ree eee 
 
 in the foregoing pages, are the Gardner-Holdt Viscometer and 
 
 the Gardner-Parks Mobilometer. 
 
 These instruments have 
 
 been particularly described because they were built for the 
 
44 Consistency 
 
 ‘paint and varnish industry in which they are extensively used. 
 In order to correlate these two instruments, the oils which 
 are used in making the bubble viscometer were run at 25° C. 
 on the Mobilometer and a curve plotted with poises along the 
 ordinate and time in seconds along the abscissa. The no load 
 curve represents the load of the system, which was 74 grams. 
 The 100 gram load represents the load of the system plus 100 
 grams, or 174 grams. : 
 
 The time, in seconds, divided by the corresponding ntimber 
 of poises gives a factor which, when divided into the time 
 
 in seconds reduited toruna svrinle: will give poises viscosity. | 
 
 Thus, if we have for the factor of the no load curve 
 
 Bp. = poises and “Tl == time per te. 
 T / : 
 Po. hor P Soe 
 9.3 | 
 and for the 100 gram load, curve eee ts. 
 a8 | ‘i 
 PS or P == 2025 e8 Bee 
 
 3.98 7 
 Seven nitrocellulose solutions were made up with various 
 
 erades of nitro-cotton. Those of the more viscous type were — 
 
 made up on a formula of 8 oz. of cotton to the gallon of solvent. 
 Those of the less viscous type were made up with 25 oz. of 
 
 nitro-cotton to the gallon of solvent. After standing several — 
 days, a sample of each was put into a standard viscosity tube — 
 for running the viscosity with the Gardner-Holdt tubes. The — 
 solutions were also run on the mobilometer and the results ~ 
 tabulated. The viscosity was then determined by the mobil- — 
 ometer method, using the factor obtained with the no load — 
 curve on Page 37. The mobilometer results are given below. — 
 
 The greatest difference between the methods is 0.1 poise. 
 
 TABLE 7 
 Seconds Required on Poises Calculated Poises Determined — 
 
 Nitro-Cotton Mobilometer at by Mobilometer by Gardner-Holdt — 
 
 Solution No Load 100 gr. Load Factor Viscometer 
 
 Nos. 15.4 6.2 1.65 G Cs 
 
 No, 2 PAN.) 8.8 2.34 1 + T+ 
 
 No. 8 6.2 2.8 66 B B 
 
 No. 4 17.0 G2 1.838 G G+ 
 
 No. 5 170.0 26.8 18.28 — — 
 
 No. 6 13.8 5.2 1.48 F Kr 
 
 NG. ot 3.2 1.8 04 A — A — 
 
 The results derived by factor are taken from the no load readings 
 
 The method that has sometimes been applied to determine 4 
 the viscosity of nitrocellulose solutions, namely, the falling” 
 
 \ c q 
 { LK 
 
 9 gr ” 
 
 aaa lel EN Per or ' 
 ee ee Se ee ee ee ee er 
 
 _ = 14 A ic 
 
Consistency 45 
 
 steel ball method, could be replaced with the mobilometer. An 
 added advantage is the fact that very exact readings may be 
 obtained with pigmented lacquers. The falling steel ball 
 method is, of course, not applicable to pigmented lacquers, 
 because of the difficulty of reading the end point. 
 
 P. P. G. Consistency Test.—A type of consistency apparatus 
 developed by the Pittsburg Plate Glass Co. and subsequently 
 used extensively for determining the consistency of pigmented 
 products, is described below. 
 
 at Uh re UTE HH 
 me 
 
 ul i! Wy yt it 
 
 load H ' 
 
 ! Pants EL a wana pate? aie Us as 
 | 
 
 KIGURE 11 
 
 Tilting Frame for Consistency Tests. 
 
 Apparatus Required.—A consistency test frame, made of 
 wood and having a wood tilting frame to hold a 10” x 12” glass 
 plate (see Fig. 11); a standardized German silver tip. For 
 a distance of one-half, inch, this metal tip has a 1/16” internal 
 diameter hole; one glass tube 131%” in length and having 1%” 
 internal diameter. ‘This is cemented to the German silver tip 
 with a paste made of litharge and glycerine; one 12” rule 
 - graduated to 1/10’; one stop watch; one 10” x 12” glass plate. 
 
 Details of Test.—Testing of paints, enamels and lacquers. 
 
 The finished product is thoroughly mixed by stirring and 
 agitation until a uniform mixture results. The consistency 
 test is then made as follows: 
 
 The glass plate is placed in a horizontal position in the con- 
 sistency test frame. The glass plate and pipette should al- 
 ways be clean and free from grease or oil. The pipette is 
 
46 Consistency 
 
 always filled exactly one-half by sucking at upper end of pi- 
 pette. Place finger over upper opening. Slightly releasing the 
 finger pressure allows the operator to control the drops. Hold- 
 ing the pipette against the notched guide, five (5) drops are 
 allowed to fall on the glass plate. As many checks as desirable 
 can be run at the same time by moving the pipette to the next 
 notch and repeating the operation. Not less than three de- 
 terminations should be made. Allow the glass to remain in a 
 horizontal position for exactly one minute after the last drop 
 hag been placed. The glass is turned to the vertical position 
 and the paint allowed to flow downward for exactly five 
 minutes by the stop watch. At the end of this time, the glass 
 is again turned to the horizontal position and the distance 
 each test has run is measured to the nearest 1/10 of an inch 
 and the average of the number of determinations taken as the 
 result of the test. 
 
 Testing of Dry Pigments——Definite weights of pigment 
 and refined linseed oil are used. Usually 30 per cent. by weight 
 of pigment in the case of zine oxides and leaded zines and 70 
 per cent. by weight of refined linseed oil are used. In the case 
 of lithopone it is advisable to use 40 per cent. of pigment and 
 60 per cent. of oil. 
 
 The acid number of the oil should be within a close range 
 of uniformity on the successive lots of oils used. (3.00 to 3.50 
 acid number is a very good average). 
 
 The pigment is placed on a marble or glass slab, a small 
 portion of the oil is added and rubbed or mulled to a perfectly 
 smooth paste with a glass muller. The balance of the oil is 
 added in small portions, mulling after each addition of oil 
 until all oil has been thoroughly incorporated with the pig- 
 ment. For convenience the oil can be added from a burette. 
 
 Practical Applications of the Spot Test—The spot test for q 
 
 consistency is clearly recognized to be limited in its applica- 
 
 tion, but when carefully used in conjunction with fixed paint ~ 
 standards or against a specified ‘‘tail length’’ limit, the spot — 
 
 test has been found very convenient and suitable. 
 
 The precautions to be followed in testing pigments are, — 
 certainty of a uniform refined linseed oil of defined acid num- ~ 
 ber, a constant and proper ratio between pigment and oil, and ~ 
 a standard method of preparing the paint with a laboratory — 
 
 muller. 
 
 a pee " . 
 , Oe ae eee ee ae eee ee es 
 
Consistency 47 
 
 Hickson Penetration Method.—E. F. Hickson of the Bureau 
 of Standards has adapted the well known penetration test for 
 asphalt to determine the consistency of paste paints which 
 range from stiff white lead in oil to the soft semi-paste paints. 
 A description of the apparatus and his method, together with 
 some very interesting results, as prepared by Mr. Hickson, 
 are given below: 
 
 NOTE—This description was originally prepared by FE. F. Hickson for 
 Scientific Section Cire. No. 300. 
 
 * FIGurRE 12 
 
 Apparatus for Determining the Consistency of Paste Paints. 
 
 _ Apparatus.—The first cone used in this work was a 45 de- 
 gree cone made of aluminum, 3.81 em. (114 inches) in diameter 
 at the top, weighing 20 g. The tip was made of steel. The_ 
 
48 Consistency 
 
 cone was made to meet the dimensions given in the Proceed- 
 ings of the A. S. T. M., Vol. 23, Part I, p. 350 (1923), except 
 that it was hollowed out to give the desired weight of 20 g. 
 The stem of the cone fitted into a plunger 13.65 em. (534 
 inches) long by 0.95 em. (% inch) in diameter, made of alu- 
 minimum tubing of a size to fit the pentrometer.* The weight of 
 the plunger was 20 g., thus giving a total moving weight of 40 
 gv. The container was a cylindrical brass cup 9.7 cm, (3% 
 inches) in diameter by 7.2 em. (2% inches) deep. (For stiff 
 pastes a smaller container can be used. The complete appa- 
 ratus is shown in Figure 12. The mirror on the left is used 
 in obtaining an image of the cone when the tip just touches 
 the surface of the paste. The thermometer, shown on the 
 right, placed in a hole for convenience, is used to measure 
 the temperature of the paste. The cone on the extreme right 
 is the one used later and proposed as a standard for general 
 use. 
 
 Procedure.—The thoroughly stirred sample is brought to 
 
 a temperature of 25° C. (+ 2° C.) by means of a water bath. — 
 
 The surrounding air should also be as close to 25° C. as pos- 
 
 sible. It is then transferred to the container and packed in so” q 
 
 as to finally have some of the paste above the sides of the con- 
 
 tainer. The excess of paste is scraped off smoothly and its sur- 7 
 face leveled by carefully drawing a straight, rigid, sharp- — 
 edged piece of steel across the top of the container. Care must — 
 
 be taken that no ‘‘skins,’’ lumps, or air bubbles are present, as 
 
 these are apt to cause incorrect results. The container is — 
 
 placed upon the stand of the penetrometer and the cone 
 
 brought down at the center of the sample so that the tip just j 
 makes contact with the surface of the paste. The indicator — 
 
 arm is carefully brought down so that it just touches the 
 
 plunger and the reading of the dial is then recorded. The : 
 
 indicator arm is pushed back and the plunger is released sud- 
 
 denly and kept released for 5 seconds (stop watch), after — 
 
 which the indicator arm is again brought down so that it 
 
 makes contact with the top of the plunger. The penetration — 
 is read directly from the scale, in tenths of a millimeter. Three ; 
 tests are made, and the average of the three determinations — 
 is reported, provided the difference between the maximum and | 
 minimum values is not more than ten points (1 mm). In the — 
 case of stiff and medium stiff pastes, several determinations — 
 
 *“Proposed Method of Test for the Penetration of Cup and Railroad — 
 
 Greases,” Proc. A. S. T. M., Part I, p. 518 (1924). 
 
Consistency 49 
 
 can be made on different parts of the same surface without 
 refilling, or the container may be refilled with a fresh portion 
 after each determination and the surface leveled as above 
 described. Care must be observed, especially in the case of 
 soft pastes, to avoid any side effects from the walls of the con- 
 tainer. This is taken care of, as in greases, by starting a test 
 so that the tip of the cone is never placed closer to the sides 
 of the can or to the edge of a previous hole than the penetra- 
 tion distance of that particular paste paint. After each test 
 the cone is thoroughly cleaned with benzol. 
 
 In Table 8 are given some readings of penetration with 
 the preliminary cone on a wide variety of paste paints. The 
 precision obtainable by the same, as well as by different 
 operators, is shown: 
 
 TABLE 8.—Penetration Results at 25° C. (+ 2° C.) Using First Cone. (40 g. 
 
 load—5 sec. Penetrations). 
 
 Pigment Penetration 
 
 No. Material % (by wt.) mm /10 Description 
 1 “White Lead in Oil.............. 92.4 67 Very stiff paste 
 gee Winkcerveadain. Oil... :....... 90.0 100 Stiff paste 
 a. White Lead in Oil............. 92.2 135 Stiff paste 
 # White Lead in Oil.............. 89.1 170 softer than No. 3 
 BomviivesLeadein Oil-.,.......:... 92.3 126 Stiff paste 
 GeV nite Lead in Oil....:........ 89.9 91 Stiff paste 
 Pew nite tea din ‘Oil.,.......:.... 89.1 f118 
 \122 Stiff paste 
 § White Lead in Oil............. 90.5 198 Softer than usual 
 (a)  () 
 (92 (96 
 Pee White Lead an Oil:............. 89.8 197 ie Stiff paste 
 97 93 
 (a)  (b) 
 1727 ee a HT 
 Poe tute ead in Oil.............. 90.3 5 \131 Softer than No. 9 
 125 
 (a) (2) 
 11 White Lead in Oil............. 89.5 0102106 
 (102 4)1101- Stiff paste 
 12 White-Lead in Oil............. 91.2 80 Very stiff—no oil 
 luster 
 See eine Uxide in Oil............... 84.2 124 Normal 
 Seneca Oxide in Oil................ 82.0 105 Normal stiff paste 
 134 
 137 
 152 
 Boeecine Oxide in Oil................ 81.8 4130 Usual stiff paste 
 133 
 135 
 132 
 ieee Oxide in Oil................ 79.8 154 Somewhat soft 
 ie ee ARO te OMmMewWNAL SOLU 
 Peo Bianc Fixe in Oil................ 79.3 250 Long and stringy 
 t> Blanc Fixe in Oil................ 65.0 184 Fairly stiff 
 
 Seance Fixe in Oil................ Toe A EL Re es ice aera A ae a 
 
50 | Consistency 
 Pigment Penetration aie 
 No. Material % (by wt.) mm /10 Description 
 OG.) “Litanor: te OM ern ae, 82.3 133 Stiff paste 
 21) 4 itanox=in Oui, roe en 80.0 {166 ; 
 \170 Fairly stiff 
 22 B.S. Cir. 89 Semi-paste.... 73.8 f4l11 Thick paint—will 
 \407 "run 
 23 B.S. Cir. 89 Semi-paste.... 76.9 305 Thicker than No. 
 
 22 
 
 24 B.S. Cir. 165 Olive Drab 
 SeMi-paste.,....cccacccsseeereds 73.0 {290 Thicker than No. 
 \291 22—will not run 
 25 B.S. Cir. 165. Olrve Drab 
 STN PARES. Justis asssleetena 78.4 {299 Will not run—me- 
 \ 300 dium thick paste 
 26 Yellow Ochre in Oil............ 78.9 310 Medium—will not 
 Pot Meni 
 27 Yellow Ochre in Oil............ ‘eel 320 Medium — thicker 
 than No. 30 
 (chrome yellow 
 in oil) 
 28 Yellow Ochre in Oil............ 74.0 314 Medium 
 29 Yellew Ochre in Giljae: 69.7 329 Medium 
 30 Chrome Yellow in Oil........ 712 [358 
 Bee Semi-paste 
 31 Chrome Yellow in Oil........ 73.8 358 Semi-paste 
 32 Chrome Green in Oil......... 71.6 f405 Thick paint (soft 
 \406 paste) ‘‘runny”’ 
 33 Chrome Green in Oil.......... 73.9 384 Soft paste, 
 4c runny ” 
 34 Chrome Green in Oil.......... 79.3 430 Thick paint—thin- 
 ner than No. 32 — 
 35 Chrome Green in Oil.......... 71.4 450 Thick paint—read- 
 ily pours 
 36 Chrome Green in Oil.......... 82.6 315 Semi-paste — will 
 not run 
 of Burnt: Umber nm Ol 2.3 49.9 360 Soft paste 
 38 Burnt Umber in Oil............ 60.1 335 Soft paste 
 39 Burnt Umber in Oil............ 58.0 388 Quite soft—will run 
 40 Burnt Umber in Oil............ 60.6 300 Medium—will not 
 run 
 41 Burnt Umber in Oil............ 58.2 f222 
 \227 Medium stiff 
 Ad) Buent Seine iO ais er ae, 278 Medium stiff 
 43°-. Burnt Siennarin wo ecee, 62.9 342 Fairly soft—will 
 just about run 
 44 Burnt Sienna-in Oil............ 61.4 304 Medium — will not 
 run 
 45. Venetian Red in Oil.......... 68.3 405 Thin paste — will 
 run 
 46 Prussian Blue in Oil.......... 52.9 eye: 
 \277 Fairly stiff 
 47 “Rew Uniberin Oil ca 58.1 268 Medium stiff 
 48 Metallic Brown in Oil........ 68.8 384 Soft—will run 
 
Consistency ay | 
 a i | el ial le Ne Ee 
 
 Pigment Penetration 
 
 No. Material % (by wt.) mm/10 Description 
 Peep oigck ity Oil............: 54.1 {250 
 1247 Medium stiff 
 90) Drop Black in Oil.............. 48.8 380 Soft paste 
 Be vampblack in. Oil.............. 36.5 ore Medium stiff 
 248 
 pea ealapblack in Oil.......:.:..... DOs Be Medium stiff 
 255 
 So) wampblack in Oil................ 35.4 344 Somewhat thin 
 34 Raw Sienna in Oil.............. 63.6 400 Very soft—will run 
 eeteed Leadin: Oil .0..:.......... 93.7 183 Stiff 
 paeenea Lead m Oil.................. 93.0 174 Stiff 
 pieoiked Leadan Oil................:. 94.0 227 Somewhat soft 
 Poemed end an Oil... 93.4 210 Medium stiff 
 Seemed Leadein Oil.........:...... 92.7 169 Normal stiff 
 60 Ultramarine Blue in Oil... 67.9 [328 Medium soft—will 
 325 not run 
 Of Urop Black in Japan........ 60.3 201 Medium stiff 
 623) Drop Black in Japan........ 56.7 236 Medium stiff 
 63 Drop Black in Japan........ 63.2 170 Stiff 
 02 Drop Black in Japan........ 56.9 279 Medium stiff 
 65 Drop Black in Japan........ 56.5 412 Runny paste—too 
 thin 
 607 Drop Black in Japan........ 58.2 375 Soft paste 
 67 Drop Black in Japan........ 48.0 450 _ Thick paint— 
 runny 
 68 Lampblack my Jaan... 26.0 450 Very thin—runny 
 
 (a) E. F. Hickson. (6) D. P. Graham. 
 
 The materials in Table 8 represent many brands, and it is 
 to be observed that the percentage of pigment does not bear 
 any definite relationship to the depth of penetration. This 
 is easily understood when the effects on consistency of such 
 unknown variables as the acid number of the oil used, size 
 of pigment particles, time and manner of storage of the 
 finished pastes, possible reaction of pigment and oil, ete., are 
 considered. A red lead of high purity (97 per cent of Bp.Gs), 
 for example, when freshly mill-ground, in identically the same 
 way, to a paste containing 93.5 per cent of red lead and 6.5 
 per cent of raw linseed oil, gave a penetration of 295 when 
 the oil was practically neutral and 207 when the linseed oil 
 
 had an acid number of 6.0. 
 
 The time and manner of storage have an important bearing 
 on consistency. Red lead in oil may become in a few months 
 so thick and hard as to be worthless. Whether other pigments 
 
52 Consistency 
 ee LL LL 
 in oil change in consistency is open to question. The only 
 figures available are the following: 
 
 Penetration 
 
 Material . mm /10 Date 
 Burnt: Sienna mm Or, aes: 304 Aug., 1924 
 Burnt Sienna in Oil........ 308 Mar., 1925 
 surnt Unber, insOil. < eoi.ies 388 Nov., 1924 
 2urnt Umber in Ol o.oo 390 Mar., 1925 
 
 These two earth colors in oil apparently did not change in consistency. 
 
 The effect of ‘‘working’’ or mixing an unworked grease is 
 to give a higher penetration reading (softer paste). Paste 
 paint materials such as putty would do the same thing to a 
 certain point. For most paste paints in oil, however, 1 1s 
 believed that after a first thorough mixing, the consistency 
 remains about the same during the test. A few data have 
 
 been optained as follows: 
 Penetration 
 
 Material mm /10 
 Zin€ Omdde: in OW. 6 ve-sig.siges erie bie sie wet eee By method... 4..0ea 133 
 Excessively mixed for 
 ten minutes after ob- 
 taining above result... 134 
 Fine Oxide in: O14. he 25 Pe eee ai ee By methoG...e256. 125 
 Excessive mixing for 
 five minutes... eee le 
 White Lead in Oil. ..... 0.5.00). Secs owes se sey SOG 105 
 Excessive mixing for 
 five Mminttes/jaeeeee os. tise 
 
 The effect of temperature on the penetration of paste paints 
 was observed on a few samples. It appears to be but very 
 
 slight. For example, the penetration of a sample of titanox — 
 
 in oil was 123 at 20°C and 130 at 40°C. While the results in 
 this paper were obtained at approximately 25°C, it is believed 
 that, ordinarily, temperature control is of smali moment. The 
 effects of load and time on penetration were also observed. 
 For most of the samples tested, the five seconds of time gave 
 practically all the penetration. In a few instances, notably 
 blane fixe in oil, the penetration was not complete in 30 
 seconds. 
 
 Recently a new cone for grease has been adopted as a tenta- 
 
 tive standard of the American Society for Testing Materials. 
 The diagram of this grease cone with the latest revisions is 
 
 shown in Figure 2 of the A. 8S. T. M. Tentative Standards, — 
 1926, p. 418. It is also shown in the Proceedings, American — 
 Society for Testing Materials, Vol. 25, Part I, p. 703 (1925), — 
 but some minor revisions have been made since this was pub- ~ 
 lished. This is a double taper cone, consisting of a 30 degree — 
 
 * Possibly some thinning. 
 
Consistency why 
 
 steel point and the upper part a 90 degree brass cone. While 
 the preliminary work with the first cone described in this 
 paper gave satisfactory results, this new cone seemed to offer 
 distinct advantages. A cone made to the dimensions of the 
 new grease cone (as shown in the A. S. T. M. Tentative Stand- 
 ards, 1926, p. 418) but much lighter, was therefore tried out. 
 The upper part of the new cone, measuring 6.51 em. (23/5 
 inches) in diameter, is made of hollowed aluminum, so that 
 
 §50 
 
 PENETRATION- TENTHS OF MILLIMETERS - NEW DOUBLE TAPER CONE 
 
 0 50. 100 =150 §=©200 ©6250 300 350 400 450 500 550 
 PENETRATION-TENTHS OF MILLIMETERS- OLD CONE 
 
 FIGuRE 13.—Comparison of Both Cones. 
 
 with the steel tip the complete cone weighs 35.7 g. and meas- 
 ures 4.32 cm. in height. The aluminum plunger weighs 14.3 
 g. thus giving a total moving weight in the test of 50 g. By 
 adding a 100-g. weight, the new cone should correspond to 
 the grease cone having a total moving weight of 150 g. In the 
 photograph the new cone is shown at the right. 
 
 The new cone (with a moving weight of 50 g.) was com- 
 pared with the 45 degree cone (40 g. moving weight) on a 
 
54 Consistency 
 
 sample of white lead in oil. This sample gave a reading of 
 128 with the 45 degree cone and 173 with the new double taper 
 cone. Raw linseed oil was then added to this paste im suc- 
 cessive portions, and penetrations obtained with both cones. 
 In order to obtain values below that of the original sample, 
 dry white lead was thoroughly kneaded into this white lead 
 in oil, finally giving a very stiff putty. 
 
 The comparison between the two cones is plotted in Figure 
 13. The decided advantage of the new cone in giving higher 
 readings on stiff pastes is apparent. On soft pastes, readings 
 become less than those obtained with the first cone. It is 
 noticed that there is a break in the curve. This break is due 
 to the two tapers of the new cone. 
 
 There are shown in Table 9 some experimental and calcu- 
 
 lated values for various paste paints, using this new cone. 
 The calculated values were obtained by determining the pene- 
 tration with the first 45 degree cone described in the prelimi- 
 nary work and then from the graph in Figure 13 reading off the 
 values for the new cone. The actual values for the new cone 
 were then determined. 
 
 TaBLE 9.—Comparison of New and Old Cones at 25° C. 
 
 Penetration 
 New 
 Old Cone Double Taper Cone 
 Heper- Cal- Haper- 
 
 Material imental culated imental 
 White Lead ‘in Oil....:. 310 295 290 
 Chrome Green in Oil.... 346 310 305 
 Yellow Ocher in Oil..... 380 330 330 
 Vermilion: In Ole. wes 160 190 198 
 White Lead in Oils 2.5 90 130 131 
 
 With very thin pastes of white lead, it was noticed that the q 
 
 displacement on the upper portion of the double taper cone 
 gave rise to slight buoyancy effects. This was not noticeable 
 in the thicker pastes. 
 
 The range of usefulness of this new cone was found to be — 
 quite similar to that of the preliminary cone first described. — 
 The precision obtainable by the one operator with the new ~ 
 instrument was about 3 per cent. Since the dimensions, in- © 
 eluding tolerances, of this double taper cone have been care- 
 
 fully worked out and standardized for grease by the American 
 Society for Testing Materials, it is recommended in its modi- 
 fied form for use in testing the consistency of paste paints. 
 
 The penetration method is believed to be of considerable — 
 value in rating different lots of the same type of material. It — 
 is certainly superior to the usual method of placing a stick 3 
 
 a ne ee See 
 
 eT ee 
 
 ~ nals atin 
 
 AS ge, ee Oe ae 
 
Consistency ao 
 
 or spatula in the can of paste paint and giving the description 
 of its consistency. With the new cone, different types of paste 
 paints can apparently be roughly grouped in the following 
 classes: . 
 
 (ONS 0. I rr less than 100 
 ee ee eed ek LOUs tam iio 
 Beirne pastes... ol ee ee lee) ines PAN) 
 Oh ee ke eb as 200 to 325 
 Perr een) Wastes... ..........-4.6.. 320 to 430 
 
 The test does not make a distinction between the length and 
 shortness of paste paints (which probably depends upon at 
 least two factors, yield value and mobility), nor does it meas- 
 ure their tackiness or stringiness. | 
 
 Flowmeter for Mobility of Enamels.—A flowmeter which 
 the writer designed a few years ago for determining the flow- 
 ing properties of various pigmented mixtures is shown below. 
 
 FIGURE 14 
 
 Two Views of Gardner Flowmeter. 
 
 The apparatus designed is shown in Fig. 14. It consists of a 
 heavy piece of plate glass having a series of concentric rings 
 
56 Consistency 
 
 1% inch apart, etched on one side, a brass cylinder for holding 
 the paint, and a frame into which the cylinder is fitted so that 
 ‘+t ean be raised vertically. The frame is fitted on two sides 
 with adjusting screws which permit accurate centering of the 
 cylinder. The instrument 1s operated by inserting the brass 
 eylinder firmly upon the plate, and filling it level with the 
 coating material to be tested. The cylinder is then quickly 
 lifted and the coating material allowed to drain out. 
 
 The plate should be carefully leveled before using. When 
 
 the cylinder is raised the material flows out covering a circular 
 aren. It is essential that the surface be absolutely clean and 
 
 FIGURE 15 
 
 View of Cylinder and Disc. 
 
 dry; otherwise the area covered by the material will not be 
 circular and readings will be inaccurate. In cleaning the 
 plate, the writers have proceeded in the following manner: 
 After a test, the plate is wiped off with a gasoline-soaked rag, 
 then thoroughly washed with soap and water, and later 
 cleansed with aleohol. A mixture of equal volumes of benzol 
 and alcohol was also found useful in cleaning the plate. It is 
 then wiped dry with a soft piece of cloth. When thus cleaned, 
 
 very smooth cireles as much as seven inches in diameter can be 3 
 
 obtained. 
 
 The cylinder may also be used in conjunction with the dise 
 shown at © in the figure, for determining the weight of a 
 
 gallon of paint or other material, where only small quantities q | 
 
 are available. It is made to contain exactly one cubic inch, 
 hence it is only necessary to multiply the weight of a cylinder 
 
 filled with paint by 231 to get the weight per gallon. Approxi- 4 | 
 
 eee ee eee a ee eS ne ee 
 
 Aare 4 ot ee Pe” ek 2 
 
Consistency ys 
 
 mate specific gravities and bulking values of the pigments 
 used in milled paints can also be estimated very quickly. 
 
 When the cylinder is raised, the paint levels out very quickly 
 at first. Paints of a thick, mushy consistency practically 
 cease flowing in from 14 to 14 minute. Other paints continue 
 to flow over a much longer period of time. Some of those 
 
 Oooo 
 EEE EEE EEE EEE Dale OVS e ars 
 2. Buneean 
 
 (C225 3880S eee | ro] 
 aioe a ey 
 
 VaR 
 
 \ 
 l 
 \ 
 \ 
 a 
 all 
 | 
 a 
 S| 
 “Hh 
 Be 
 I 
 a 
 
 be 
 & 
 ig 
 | 
 | 
 = 
 t 7 
 \ 
 
 N 
 im 
 ms 
 |_| 
 fe 
 : 
 EELS 
 HBROE 
 SERS i 
 
 BAe 
 aie 
 5 
 
 a 
 isl 
 NI 
 ee 
 A |] 
 \ 
 A 
 ly 
 THEE 
 : 
 Am 
 aia 
 
 uo 
 . 
 iN 
 as 
 ; 
 | 
 | 
 Bites 
 
 bd 
 By 
 ie 
 E 
 MW 
 | 
 : 
 isi 
 aie 
 
 Diameter of flow in inches 
 
 Time in minutes 
 
 1, Raw Linseed Oil 3, Zinc Oxide in Raw Linseed Oil 
 2, Spar Varnish 4, Zine Oxide in Spar Varnish 
 Figure 16.—Curves from Results on 
 
 examined were still flowing appreciably after 10 minutes. 
 These differences in rate and extent of flow might be explained 
 by reference to yield value, which is defined as the resistance 
 to flow due to the friction of the pigment particles. The hydro- 
 Static head of the material causes the paint to flow, while the 
 yield value opposes flow. High surface tension also tends to 
 decrease flow. The effects of both yleld value and surface | 
 tension probably remain constant (during a determination), 
 
58 Consistency 
 
 while the hydrostatic head gradually decreases. We thus 
 have the hydrostatic head opposing the combined forces of 
 yield value and surface tension. 
 
 The paint continues to flow until the opposing forces are 
 equal, that is, until the hydrostatic head has fallen to such a 
 value that it no longer exceeds the combined effects of yield 
 value and surface tension. Paints of good flowing properties 
 would therefore have low yield values. Low surface tension 
 would also promote flowing. 
 
 A little difficulty was experienced at times in controlling 
 temperature which, of course, has considerable influence on 
 flow. On cold mornings it was necessary to heat the plate and 
 then allow it to cool to room temperature before using. With 
 the laboratory maintained at 70-75° F., it was possible to check 
 results quite closely, usually to 144 inch diameter of flow. The 
 results obtained by different operators also checked very well. 
 
 During the course of the work a large number of determina- 
 tions were made. Some of the results are given below. 
 
 TABLE 10 
 
 Dry LitHoponges GROUND IN LINSEED O1L*—Diameter of Flow in Inches 
 
 Time in Yo 3 AE a A 3 4 5 < 10 
 
 Minutes 
 
 Noe ieee 30541304 1334 |334-41934-+1924-+1324-41324-41934-415344 1934-4 
 eo 254 los -+ 1256-41296 |256-+|254-+|254+|296-+|294-+|256-4256+ 
 Se ie 94 (294 (284 \294 [294 [asa |asq+lode+|234+|284+[284+ 
 Oe 3. bs Ie 4+ [sb lee ego 
 Ce eens 34 4 b+ Br b+ B+ [3eaieeeeeene nares 
 No. 8. /svertau [33a [aoa [334+ l3x-+13%4-4 1934-41344 (394 +3344 
 
 * All paints were made up in the proportion of 100 grams pigment to 100 grams — 
 
 raw linseed oil, In this proportion some samples yielded products of much heavier 
 body than others. 
 
 ey, CPR ee ee ae ee te 
 
 ee a ey ee 
 
CHAPTER III 
 
 HARDNESS AND ABRASION RESISTANCE 
 
 Methods for determining the hardness of varnish films have 
 been greatly desired. With a suitable method much informa. 
 tion regarding the comparative value of various varnishes for 
 
 a foo 
 
 i= Vy Sd. 
 
 —- 
 
 ei; 
 “aN 
 
 UMMM EZTV 
 
 HIGURE 17 
 
 Design of apparatus showing weighted sapphire needle on coated 
 ; surface. 
 
 use in floor coatings and for similar purposes could be ob- 
 tained. In this chapter are described various methods that 
 have been proposed for determining the hardness of films, to- 
 gether with a piece of apparatus recently devised at this 
 laboratory for this purpose. 
 
 Laurie-Baily Apparatus.—An apparatus developed by Dr. 
 A. P. Laurie and F. G. Baily of Heriot-Watt College, Edin- 
 burgh, is described by Holley* as follows: 
 
 An instrument for this purpose has been devised by Dr. A. 
 P. Laurie and F. G. Baily of Heriot Watt College, Edinburgh, 
 the essential features of which are a central rod sliding easily 
 in a vertical direction through holes in two brackets. The 
 upper portion of the rod has a screw thread, on which is a run- 
 ning nut. By means of a milled head at the top the rod is 
 twisted round, and the nut caused to travel up and down on 
 the thread. A spring is attached at its upper end to the travel- 
 ing nut at the lower end to the lower bracket. To the lower 
 end of the rod is attached a hardened blunt steel point, and the 
 varnished plate to be tested is placed under this point, and 
 the point brought to the surface of the varnish The test 
 Surface is drawn slowly under the point, the pressure being 
 
 7—_—_-__ 
 “Analysis of Paint and Varnish Products, 274. 
 
60 Hardness and Abrasion Resistance 
 
 ‘nereased until a white scratch is observed, at which point the 
 reading is noted on the scale. The machine reads to a maxi- 
 mum of 2000 grams. Spirit varnishes break down at a pressure 
 of about 100 grams, rosin varnishes 200 to 400 grams, fairly 
 eood common varnishes at about 700 grams, and fine carriage 
 varnishes at 1200 grams and upwards. The inventors claim 
 that the best oil varnishes take twelve months to reach their 
 maximum hardness, and that the rate of drying and the ulti- 
 mate hardness can be measured with accuracy by their instru- 
 ment. 
 
 Fraure 18.—Clemens Apparatus showing weighted knife on coated panel. 
 
 A set of this apparatus obtained by one of the writers as far 
 back as 1910 was available in this laboratory for experimental 
 purposes and was used in a number of determinations, de- 
 scribed later in this chapter, upon a series of varnishes. 
 
 Clemens Apparatus.—Another apparatus for determining 
 hardness of varnish films, known as the Clemen’s* Hardness 
 Tester (see Fig. 18), and made in Germany, consists of a bal- 
 ance beam with one arm slightly longer than the other. The 
 longer arm carries on the under side a portion of a knife 
 blade, and on the upper side a post upon which are placed — 
 weights. The sample is placed on a holder and drawn along — 
 under the knife blade. The weight and the nature of the ~ 
 scratch are then considered in determining the hardness of the — 
 sample. From a few experiments made with this apparatus, 
 
 *Made by Hugo Kenl, Dresden. 
 
Hardness and Abrasion Resistance 61 
 ss Ga SE aed rere ae ines 
 it is not believed that it offers any advantage over the type 
 referred to on page 59. 
 
 Wilkinson Pencil Method.—Another method for determining 
 the hardness of varnish films was outlined by W. H. Wilkin- 
 son in his paper, entitled ‘‘Methods for the Determination of 
 Comparative Hardness of Varnish Films”’ (see page 302 of the 
 Proceedings of the Scientific Section for 1923).* For this 
 method, seventeen grades of Dixon’s Eldorado pencils are 
 used. These pencils are drawn across the varnish film until 
 an end point is reached. This end point is indicated when one 
 pencil is found which will not cut the varnish, leaving a black 
 pencil mark on the surface, whereas the next harder pencil 
 will cut through the varnish without leaving a black mark. 
 The number on the harder pencil is then used to express or 
 designate the hardness of the varnish. The pencils used by 
 the writers are numbered as follows (only twelve were used 
 in the tests reported here) : 7H, Giivoleeh. 3H 2H ae a Bb 
 B, 2B and 3B. 
 
 This method is, of course, open to such objections as the 
 impossibility of applying the same pressure by different oper- 
 ators; possibility of different operators holding the pencils 
 at different angles; lack of uniformity in the sharpness of the 
 pencil points; and in the hardness of pencils of a particular 
 number that are purchased from lots in various sections of 
 the country; and the freedom from hard spots in the graphite. 
 
 Laboratory Scratch Hardness Tester.—The writer has at- 
 tempted to eliminate some of the difficulties offered above by 
 devising an apparatus constructed upon a balance beam simi- 
 lar to a Westphal balance for determining specific gravity. 
 At one end of this beam a clamp is fixed, which will hold a 
 pencil at an angle of 45° to the beam and pointing away from 
 the fulerum. At the other end of the beam a wei ght is placed 
 so that the beam will be exactly in balance. A hook, upon 
 which the weight is hung, is placed midway between the ful- 
 erum and the pencil point, in such a position that the weight 
 bearing on the pencil point is approximately half the applied 
 weight. In a later model, an arrangement was made for the 
 weights to be applied at the top of the beam rather than to 
 be hung under the beam. In maklIng the test, the varnished 
 
 * Scientific Section Circulars are published monthly at this laboratory and 
 forwarded to all members of the American Paint and Varnish Manufacturers 
 Association. 
 
62 Hardness and Abrasion Resistance 
 
 plate is placed under the pencil points, the desired weight 
 applied, and the plate then drawn slowly under the points im 
 the direction away from the fulcrum. 
 
 In the investigation work, the pencil points were sharpened 
 in a number of different ways, namely, on a pencil sharpening 
 machine, by rubbing the pencils on sand paper to a flat, chisel- 
 like point, and by rubbing the pencils on sand paper to a 
 rounded point. As a result of this work, it is the writers’ 
 opinion that the most important source of error in the use of 
 pencils is due to-the point used, as the pencils cannot be 
 sharpened to exactly the same point. Small pieces of graphite 
 may chip off of a very hard pencil, while a soft pencil will 
 wear away very rapidly. Entirely different results were ob- 
 tained with the different methods of sharpening, on something 
 like three hundred different determinations. The writer is 
 frank to admit, however, that no definite statement can be 
 made that there is a lack of uniformity in the hardness of the 
 
 pencils used or in the graphite used in their manufacture. — 
 
 However, such difficulties might arise at any time and might 
 tend to vitiate the results obtained by different operators. 
 
 A still further set of apparatus was constructed to hold eight 
 of the pencils of varying degrees of hardness at one time. 
 They were set in a clamp at an angle of 45° to the beam, and 
 pointing away from the fulcrum. The varnished plate was 
 drawn under them and then examined. It was found impossi- 
 ble to get the pencils in perfect alignment, and the rapid wear- 
 
 ing down of the soft pencils added to the difficulties encount- — 
 
 ered. This apparatus was therefore discontinued in the tests. 
 
 Sapphire Point Talking Machine Needle.—As a result of a — 
 later thought, it was decided to include in this investigation — 
 a sapphire point needle such as is used quite extensively upon — 
 talking machines in place of steel needles. The needle was ~ 
 fastened to a glass rod which was inserted in the apparatus in ~ 
 place of the pencil. It was found, however, that this needle, g 
 even without any weight, was able to scratch any type of 4s 
 varnish film. Nevertheless it was found by microscopic ex- ~ 
 amination of the scratched test plates that very marked differ- g 
 ences were shown in the character of the abrasions made by ~ 
 the sapphire point. For instance, it was found that boiled oil — 
 coatings and long oil spar varnishes almost invariably showed ~ 
 a type of rupture that was different from that indicated by ~ 
 
 le i a gS arn 
 
 et a , » ’ 
 ee ee a” a € w 
 
 at 
 
 Ne Ve ae 
 
 et 
 ee 
 
| Hardness and Abrasion Resistance 63 
 ——$—— 
 hard drying varnishes. That is brought out in the photo- 
 micrographs attached herewith. As a result of this work, it 
 is indicated that in place of pencils, the apparatus shown in 
 the illustration Fig. 17 could be fitted with a sapphire point 
 needle, and a qualitative interpretation of the results made 
 after microscopic examination of the films. Nothing in the 
 way of quantitive data would result. 
 
 I—Sapphire point test at 500 grams on flat white paint dried 15 days. 
 Ii—Sapphire point on hard varnish film. III—H2 pencil. IV—H5 
 pencil at 200 grams on varnish dried 15 days. 
 
 FIGURE 19 
 
64 Hardness and Abrasion Resistance 
 
 V—aAuto finishing varnish. VI—Thirty gallon tung oil spar. ViI—Twenty 
 gallon tung oil spar. VIII—Floor varnish. IX—Shellac. X Congo 
 linseed spar. All tests made with sapphire needle at 200 
 grams on films dried 15 days. 
 
 FIGURE 20 
 
XI—2B pencil on gloss white. XII—3H pencil on flat white. XIII—B pencil 
 on gloss white. XIV—7H pencil on flat white. XV Sapphire 
 point test on flat white. XVI—Sapphire point on gloss 
 
 white. All tests made with our apparatus on films 
 . dried 30 days. 
 
 FIGURE 21 
 
66 Hardness and Abrasion Resistance 
 
 Tungstone Point.—A tungstone point that was used for 
 playing several records was tried in the apparatus. This point 
 ‘s much less hard than a sapphire point or steel point. It was 
 found by miscroscopic examination that the wear on one side 
 of this point makes a great deal of difference in the breaking 
 of the varnish film. When the flat side is used, no abrasion of 
 the film was noticed until large weights were applied. When 
 the pointed side was used, the film was broken with only a 
 very small weight. It 1s not believed that the Tungstone point 
 offers any advantages in this work. 
 
 Preparation of Films.—For the experimental work, var- 
 nishes were flowed upon several small glass panels in the 
 usual manner, standing them vertically to dry. Some of the 
 glass plates used were given a rough surface by grinding 
 with coarse emery powder and then rubbing down with fine 
 emery powder; the varnishes later being applied. No differ- 
 ence, however, was shown in the value of the two different 
 types of plates for, this purpose. h 
 
 One of the glass plates used in the experiments, after being 
 coated, was allowed to dry for forty-eight hours and then was 
 ruled off into a number of small (14-inch) squares. Such a 
 great variation in apparent hardness was obtained with the 
 Laurie and Baily apparatus that it was thought impossible 
 to obtain an accurate reading on any one of the given squares — 
 of the plate. For instance, where the varnish flowed from the — 
 top of the plate, a harder surface was shown than near the — 
 bottom of the plate where the varnish had accumulated to a 
 thick film during drying. This result indicated the necessity — 
 of having a uniform thickness of film over the entire area of — 
 the glass plate. Accordingly, a revolving dise was con- 
 structed, using the type of apparatus described by Walker 
 and Thompson in their paper on the ‘‘Physical Testing of 
 
 Varnishes’’ (Proceedings of the Amer. Soe. for Test. Mater., 4 
 
 1922. Part II, page 464). It was driven by a small motor 
 
 available in the laboratory, at a speed of 300 R. P. M. The ~ 
 
 glass plate was inserted in the top of the apparatus, a definite 
 amount of varnish poured on the middle of the panel, and the — 
 motor started. After spinning for a period of three minutes, . 
 the panel was taken out and allowed to dry. The films ob- — 
 tained with this apparatus were much more uniform and 
 entirely satisfactory for the purpose of the investigation. 
 
Hardness and Abrasion Resistance 67 
 
 A number of varnishes were then selected, with a view of 
 obtaining variation in the hardness of the dried films. - These 
 were spun in the apparatus referred to, dried, and allowed to 
 harden for different periods of time before testing. It was 
 thought that it would be of interest to include in the investi. 
 gation some prepared paint and enamels. Accordingly, several 
 gloss paints and enamels were brushed out on glass plates. 
 Others were whirled in the same manner as the varnishes. 
 The charted results of tests are given in the diagram below. 
 
 Discussion of Tests—It will be noticed from the results 
 obtained with the mechanically held pencils that each film 
 shows a progressive hardening from 24 hours to 48 hours, and 
 again at the end of nine days, the different periods at which 
 each film was examined. This is true of almost every film 
 tested. The progressive increase in hardness referred to was 
 also noticed when the Laurie and Baily apparatus was used. 
 The results obtained when a number of the varnishes are 
 compared show a very little difference, all of them falling 
 within very narrow limits after drying the same length of 
 time. It was also found to be practically impossible to differ- 
 -entiate between varnishes which, because of their varying 
 composition and methods of manufacture, are considered to 
 be of varying degrees of hardness, when the Laurie apparatus 
 or pencil test was used. 
 
Hardness and Abrasion Resistance 
 
 68 
 
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Hardness and Abrasion Resistance 69 
 a 
 Dupont Scratch Testing Machine—The type of instrument 
 used at the du Pont lacquer plant at Parlin, N. J., for deter- 
 mining the hardness of a lacquer and its resistance to scratch- 
 ing, is Shown in Fig. 22. 
 
 FIGURE 22 
 
 Dupont Scratch Testing Device. 
 
 This consists of a wooden base on which are mounted (1) 
 a fulerum holding a graduated lever equipped with weights 
 and: a needle point; (2) a transformer; (3) a six-volt lamp, and: 
 (4) a metal plate. These parts are all connected in series 
 with the transformer, the latter being used to step down the 
 ordinary light voltage to the voltage of the small lamp used. 
 
 Method of Testing—The metal panel to be tested, usually 
 polished brass, is placed coated side up on the metal plate 
 under the needle point. The weight is adjusted and the panel 
 drawn along the plate by the operator in the direction of the 
 long axis of the instrument. This operation is repeated, using 
 each time an increased weight, until the lacquer is Steal 
 by the needle. When the needle penetrates the lacquer, elec- 
 trical contact will be made throughout the system which will 
 light the lamp. The position of the weight is then read which 
 Shows the pressure acting on the needle point when penetra- 
 tion occurred. Comparisons may be made on products of 
 different compositions by using a film of the same thickness 
 in each case. 
 
 D. V. Gregory has recently examined twenty-six different 
 methods for determining hardness, including those embody- 
 ing the principles of enone crushing, bendine or impact, 
 
70 Hardness and Abrasion Resistance 
 
 which he concludes are impractical. He has studied pene- 
 tration tests such as those which are represented by the de- 
 vices of Keeps, Unwin and John, but has not found them 
 suitable for such work. He has also studied the various 
 seratch methods, many of which have been outlined above, as 
 well as others which are represented by the Turner Schero- 
 meter and the micro-hardness test. His conclusions are to 
 the effect that the method devised by Dr. A. H. Pfund, and 
 described on page 82, is superior to any of the others that have 
 come to his attention. 
 
 Swinging Beam Hardness Test.—A method recently devised 
 by P. H. Walker and L. L. Steele of the Us $8. Bureau of 
 Standards, with an apparatus called The Swinging Beam, has 
 been used in this laboratory for three years with generally. 
 satisfactory results. A deseription of the apparatus, the 
 method of test, and some experimental results as originally 
 prepared by P. H. Walker for Scientifie Section Cireular No. 
 229 are given below. 
 
 FIGURE 25.—The Swinging beam for testing hardness of films. 
 
Hardness and Abrasion Resistance 71 
 
 The initial idea for a swinging beam to measure the hard- 
 ness of varnish films came from the ‘‘Herbert Pendulum 
 Hardness Tester’’ invented recently by Edward G. Herbert 
 in Kngland.* | 
 “The Herbert pendulum consists of a rocking device weigh- 
 
 ing 2 or 4 kilograms with a one millimeter supporting ball of 
 ruby or steel. Normally the center of gravity is adjusted until 
 it is a fraction of a millimeter below the center of the ball. 
 With the ball resting on the metallic surface to be tested the 
 device is set into oscillation through a very small range and 
 the time for ten swings is taken. This time varies with the 
 nature of the metallic surface to be tested and is called the 
 ‘pendulum time hardness number.’ The device may also be 
 tilted from the horizontal through a standard angle and then 
 ‘released. The angle reached at the end of the unmediately 
 ensuing half-swing is read by means of a spirit level and scale 
 on the device and is recorded as the ‘scale hardness number.’ ”’ 
 
 Tt will not be expected that the Herbert device designed 
 for testing metal surfaces would be applicable to varnish 
 films. After some experimentation the so-called swinging 
 beam (see Fig. 23) was devised. It is simply an instrument 
 for rocking two equally loaded ball bearings on a varnish 
 surface, the theory being that the harder the surface, the less 
 damping effect there will be on the movement of the balls. 
 
 The swinging beam as here described differs from the Her- 
 bert pendulum in that the period of swing is the same (with- 
 in experimental error) on all surfaces whether relatively hard 
 or soft. Hence it gives no ‘‘pendulum time hardness number.”’ 
 The ‘‘swinging beam factor’’ obtained and described later is 
 probably related to the ‘‘seale hardness number’’ of Herbert; 
 but differs from it in that it is dependent upon repeated 
 (rather than a single) deformations. 
 
 It was found that if the swinging beam was set in motion 
 on a varnish film known to be soft, it would come to rest much 
 more quickly than on a varnish film known to be relatively 
 hard. Experimentally it was not found advisable to wait for 
 the beam to come to rest. The beam was set in motion through 
 an arbitrarily chosen amplitude and the time taken when that 
 amplitude had decreased a definite percentage (for example, 
 50 per cent). The detailed description of the operation of the 
 
 *Discussed in The Engineer for June 29, 1925. 
 
JZ Hardness and Abrasion Resistance 
 
 swinging beam is given later. In the description of the con- 
 struction of the swinging beam to follow, it should be noted 
 that an attempt has been made to simplify the design as much 
 as possible so that working duplicates can be made from easily 
 procured materials in any ordinarily equipped machine shop. 
 
 Construction of the Arms.— Figure 24 gives details of the 
 construction of the arms of the swinging beam. Steel drill 
 rod was selected because of its rigidity and its uniformity in 
 dimension for a given gage size. The bends can best be made 
 in a vise. The measurement 10.5 em. shown in the drawing 
 
 FIGURE 24 
 2 DETAILS FOR CONSTRUCTION OF ARMS. 
 6-32 THREAO 
 
 , 
 arg 
 x % 
 ‘ 
 
 <i 
 
 MADE FROM NO28S STEEL DRILL ROO 
 
 (STV88S STEEL WIRE GAGE) 
 O/AMETER = 0.13924.0005 IMH (SF5X .O15 1m) 
 TEMPER 70 BE ORAWN AT BENDS 
 
 3Z THREAO_| 
 Se Dae [TT LLL 
 
 represents the distance from the longer arm to the center of 
 the 45 degree bend. It will be found advisable to draw the 
 temper of the steel at the bending points in order to avoid 
 possible fracture. After the proper thread has been cut, the 
 long end of each arm should be filed to a V shaped point (See 
 Fig. 26) which serves as a pointer. Each completed arm 
 should weigh 33 grams + 0.25 g. 
 
 Details for making the brass plate are given in Fig. 25. 
 Place two polished half-inch steel ball bearings on a level 
 surface and clamp. the brass plate over them so that they fit 
 snugly in the proper holes. The top of neither ball should 
 extend above the surface of the plates if the holes have been 
 drilled to the proper size. Completely fill the space over the 
 balls with solder, using a suitable flux, and then file the excess 
 of solder flush with the brass plate. The completed ball-bear- 
 ing plate should weigh 25 gram + 0.3 g. 
 
Hardness and Abrasion Resistance iiss 
 
 FIGURE 25 
 
 OETHILS OF BALL. BEARING PLATE. 
 
 70 BE MADE OF SHEET BRASS 
 LS MM THICK 
 
 Assembly of Parts—The important dimensions of the as- 
 sembled swinging beam are shown in Fig. 25. Attach the 
 arms to the ball-bearing plate with four brass nuts which 
 should have a total weight of 4 grams + .04 g (approximately 
 1 gram each. Clamp the arms in a vise so that their plane 1s 
 at right angles to the long edge of the plate. Tighten the nuts 
 and adjust the distance between the pointer tips to 58 em., with 
 a wire fastened as shown in the sketch and weighing 0.8 gram 
 + 0.05 ¢. (Steel wire American wire gage No. 26 is suitable.) 
 Place the assembled beam in a vertical position with the 
 pointer tips on a level surface and measure the vertical dis- 
 tance to the highest point of each arm as shown in Fig. 26. 
 This distance should be 24.5 em. (+ 0.8 em.) and should be 
 the same for each arm. If this distance falls outside the above 
 limits or if the distance is not the same for both arms, make 
 the proper correction by changing the position of the nuts_ 
 which fasten the arms to the plate. Place the seven brass 
 counterpoise nuts on the pointer end of each arm. Hach set 
 of nuts should weigh 7 gram + 0.07 g and they should be 
 
74 Hardness and Abrasion Resistance 
 
 adjusted to the above weight by suitable means, such as filing 
 or adding solder, if their weight is not correct. It will be noted 
 that the arms of the assembled beam will be slightly bowed in 
 shape owing to the tension of the connecting wire. The com- 
 pleted beam should have a total weight of 110 grams + 1 
 gram. | 
 
 FIGURE 26 
 
 OETAILS FOR ASSEMBLY OF BEAM. 
 
 ppt hg 
 § i) vy 
 re * 
 + ™“ 
 N 
 
 SY _-7 BRASS NUYS 6-32 THREAD % gue 
 WEIGHT OF EACH NUT = / 644. <) ») 
 - 
 
 a 
 * 
 
 Construction of the Scale——The distance from the center of 
 a ball to either pointer tip in the completed swinging beam 
 should be very close to 32.5 em. The pointer of the beam will 
 therefore travel along a portion of the are of a circle with a 
 radius of 32.5 cm. A general idea of the seale can be obtained 
 from Fig. 26. Draw on suitable paper a 90° portion of the 
 are of the afore-mentioned circle and lay off two radii at right 
 angles to each other. Bisect the 90° are thus formed and con- 
 tinue the bisection of the resulting angles until the are has 
 been divided into 32 equal parts. Consider the horizontal 
 radius as the top boundary line of the scale and mark the 
 ninth division below this line as the zero point. Mark the 
 division lines on either side of the zero point which correspond 
 to an amplitude of swing of 45 and 22.5 degrees, respectively, 
 as Number 4 and Number 2 scale divisions, respectively. 
 Mount the scale on a suitable vertical support so that the top 
 boundary line of the scale will be parallel to the laboratory 
 
 bench. The portion of the are of the circle not included in’ 
 
 the working range of approximately 50° of are may be cut 
 away for convenience. 
 
 Method of Using the Swinging Beam.—It was found abso- 
 lutely necessary to protect the beam from air currents during 
 
 4 oy TTT ring Pel eta 
 
 a ae eee 
 
Hardness and Abrasion Resistance 75 
 
 the period of swinging. The analogy between the swinging 
 beam and a delicate analytical balance, which is always en- 
 closed in a glass case, is readily seen. It is obvious that any 
 eabinet with a movable glass door in which the swinging beam 
 ean be mounted will serve the purpose. Two parallel, hor1- 
 zontal lines should be drawn on the glass door at the same 
 respective heights from the laboratory desk top as the 45 and 
 99.5° divisions on the scale. These lines are an excellent guide 
 to the eye in the proper alignment of the pointer tip with the 
 scale divisions. 
 
 It was found that different beams, constructed as described 
 above, gave slightly different readings on an arbitrarily 
 chosen surface. It was therefore necessary to adopt some 
 standard surface of reference in order to make a correction 
 for such deviations in different beams. Plate glass was selected 
 for such a reference standard on account of its ready avail- 
 ability and its relatively smooth and plane surface. The 
 method of determining the plate glass blank for the swinging 
 beam is given below. The measurements on varnish films 
 with the swinging beam are made in essentially the same 
 manner. 
 
 Figure 23 should be consulted for the general arrangement 
 of apparatus. The glass cabinet to protect the swinging beam 
 from air drafts is not shown in this photograph. Thoroughly 
 clean the plate glass and the ball-bearing surfaces of the 
 swinging beam with ether. Polish these surfaces with a suit- 
 able material such as strips of clean filter paper. Hemove any 
 visible lint or dust with a fine camel’s hair brush. In case the 
 ball-bearing surfaces become tarnished or do not have a high 
 polish, rub them lightly with a paste of polishing emery and 
 oil on a soft cloth. The emery must be at least as fine as the | 
 American Optical Company’s No. 303 grade. Thoroughly 
 clean the ball surfaces as described above after such treat- 
 ment. 
 
 Place the glass plate on three rigid pegs spaced to form an 
 equilateral triangle and fastened in a support of adjustable 
 height that is also equipped with leveling screws. (See Fig. 
 93). The three pegs should be located near the outer edge of 
 the plate in order to produce the maximum rigidity. 
 
 Level the plate with the leveling screws. _A ball bearing is 
 a convenient leveling guide since it will tend to roll on a 
 
76 Hardness and Abrasion Resistance 
 
 sloping surface. Bring the top surface of the plate to the level 
 of the horizontal top boundary line on the scale so that the 
 pointer of the beam will travel along the are on the scale. 
 
 Place the swinging beam on the glass plate and adjust the 
 position of the pointer to the zero mark on the scale by raising 
 or lowering the brass nuts at the ends of the arms. In case the 
 pointer can not be brought to the zero mark in this manner 
 it is an indication that the beam was not constructed accord- 
 ing to the specifications given above. Place the scale so that 
 the pointer of the beam will travel in a plane parallel and 
 near to the scale. 
 
 The swinging beam should have a period of approximately 
 _ 36 swings per minute. Start the beam in motion through an 
 amplitude of approximately 45 degrees of are. With a stop 
 watch measure the time that it takes the pointer to pass the 
 zero mark 36 times. This time should be within the limits of 
 58 to 65 seconds. If the rate falls outside these limits, raise or 
 lower the brass weights on each arm to increase or decrease, 
 respectively, this period. If this adjustment does not effect 
 the desired result, increase or decrease the distance between 
 the pointer tips by a readjustment of the connecting wire to 
 increase or decrease, respectively, the period for 36 swings. 
 Do not adjust the distance between the pointer tips outside 
 the limits of 57.5 to 58.5 em. When the beam has been ad- 
 justed for the proper period of swing, it is ready for the blank 
 run on plate glass. 
 
 Readjust the pointer, if necessary, so that it coincides with 
 
 the scale zero mark when at rest and then carefully push the 
 
 pointer to a position approximately one-half a division beyond 
 the fourth scale mark (corresponding to an amplitude of 
 swing of slightly over 45° of arc). Close the door of the pro- 
 tecting cabinet and align the eye with the fourth seale division 
 line by aid of the guide line marked on the glass door of the 
 cabinet. Start a stop watch when the pointer tip at the top of 
 the swing coincides with scale line number four. Stop the 
 watch when the amplitude of swing has decreased 50 per cent. 
 that is, when the pointer tip coincides with seale line number 
 two at the top of the swing. This period of time is the ‘‘glass 
 swing’’ of the beam and its use is described below. While the 
 time is recorded in the smallest intervals indicated by the 
 stop watch, it is evident that it is given in multiples of the 
 
 ’ rs P ~ a whe wn Wi 
 
Hardness and Abrasion Resistance 77 
 ——E—_—_—_—_—___—_—_—_—— 
 time of one swing. Hence, although more tedious, the number 
 of swings may be counted and the stop watch dispensed with. 
 
 Table 12 gives characteristic data for four swinging beams 
 and indicates the need for the blank swing on glass in order to 
 correct for the slightly different values obtained with different 
 beams on the same varnish film. The ‘‘swinging beam factor’? 
 given in Table 12 is calculated by dividing the time swing of 
 the beam on varnish by the corresponding measurement on 
 glass. Results are shown in Table 13 for two amplitudes of 
 swing, 45° to 22.5° and 45° to 11.25°, respectively. In all 
 succeeding work, the former amplitude of swing has been 
 selected as the most suitable one for general use. A. three- 
 week-old spar varnish film prepared as described in paragraph 
 IV (b) was used in the comparison of the four swinging beams. 
 
 TABLE 12 
 Typical Data Obtained with Four Different Swinging Beams. 
 (All values for swing of the beam represent the average of five determinations 
 7 expressed in seconds. ) 
 
 Beam Beam Beam Beam 
 No. 1 No. 2 No. 3 No. 4 
 45 to 22.5° Swing on Glass 345.5 331.1 330.7 338.1 
 45 to 22.5° Swing on Varnish 200.9 190.7 192.4 193.2 
 45 to 22.5° Swinging Beam 
 Factor for Varnish....... 0.582 0.576 0.582 0.572 
 45 to 11.25° Swing on Glass 792.2 749.1 761.4 773.5 
 45 to 11.25° Swing on Var- 
 SIC a) ik laa ee a eee 359.5 3338:5 334.9 338.9 
 45 to 11.25° Swinging Beam 
 Factor for Varnish ...... A454 445 440 438 
 Time Period for 36 Swings 
 PRACT E aia elas ie he eww a Phe 60.7 nS. 58.0 60.2 
 Total Weight of Beam.... 110.7¢ 109.0 g 110.6 g 110.0 ¢g 
 
 Table 13 shows additional characteristic data for the swing- 
 ing beam. It is to be noted that the time period for 36 swings 
 
 THE SWINGING BEAM METHOD OF TESTING VARNISH FILMS 
 
 TABLE 13 
 Miscellaneous Data on the Swinging Beam 
 
 (All determinations made with the same instrument and the time expresed 
 in seconds. ) 
 
 Time necessary for 45° to 22.5° Swing 45° to 11.25° Swing 
 
 6 Swings on pol- on pol- on pol- on pol- 
 
 on plate on Spar on plate ished ished on plate ished ished 
 glass varnish glass steel quartz glass steel quartz 
 60.2 60.0 343.6 344.8 346.5 788.0 794.8 797.4 
 60.2 60.2 342.5 343.5 342.9 786.4 791.3 790.2 
 60.4 59.8 341.0 349.0 343.0 780.6 810.2 780.8 
 59.9 60.1 344.8 347.4 346.4 784.2 806.0 796.8 
 59.8 60.3 344.8 343.0 344.2 778.6 97.7, 783.8 
 
 Av. 60.1 Av. 60.1 Av. 343.3 Av. 345.5 Av. 844.6 Av. 783.6 Av. 800.0 Av. 789.8 
 coo seen ces mee ee ERR BT RC SRI aA a OC a SLA RN Meal gL ER Cas Ber ee 
 
78 Hardness and Abrasion Resistance 
 
 of the beam is independent (within the limits of experimental 
 error) of the surface used. It is also to be noted that the 
 swinging beam behaves essentially the same on plate glass, 
 polished steel and polished quartz, respectively. The order of 
 the deviation to be expected between separate determinations 
 with the swinging beam on the surfaces mentioned above is 
 also notworthy. 
 
 Preparation of Varnish Films.—A standard method for pre- 
 paring varnish films was obviously necessary in order to 
 obtain results of a reproducible nature. The whirling disk 
 method of Walker and Thompson* was adopted for the prep-. 
 aration of all varnish films in this work. This method makes 
 it possible to reproduce varnish films of uniform thickness 
 for any given sample though it would be expected that differ- 
 ent varnishes would give films of different thickness. Glass 
 plates approximately 25 em. in diameter were used, but the © 
 size of the plates is not an essential factor. It is probable that 
 square plane surfaced plates would work satisfactorily. In 
 the work described below, the middle of the plate was covered 
 with an excess of the respective varnish and whirled at 300 
 R. P. M. for three minutes. This method probably yields a 
 considerably thinner film than an average brushed coat of the 
 same varnish. This fact is immaterial because the swinging 
 beam yields comparative figures and not absolute values. 
 
 Measurements on Varnish Films.—In all eases five meas- 
 urements with the swinging beam were made on a given var- 
 nish film at equally spaced locations, at a fixed distance of 5 
 cm. from the edge of the glass plate to the center of the ball- 
 bearing plate. <A circular cardboard guide with rectangular 
 holes approx. 15x40 mm. at the proper points used as a guide 
 under the test plate was found to be convenient. 
 
 As might be expected, varnish films prepared by the whirl- 
 ing disk method were not absolutely uniform and consequently 
 showed some variation in the swinging beam measurement at 
 different points. It was decided that the average of five read- 
 ings would furnish a value sufficiently accurate for ordinary 
 purposes, and that the greater degree of accuracy which might 
 follow from a larger number of measurements would not justify 
 the added labor and time. 
 
 *Proceedings of the Am. Soc. for Testing Materials, Vol. 22, Part II, p. 465 
 (1922). . | 
 
Hardness and Abrasion Resistance 79 
 
 The data given in Table 14 are intended to show the order 
 of the deviation in readings which may be expected on 
 whirled varnish films. Incidentally these data show the pro- 
 gressive hardening for three distinct types of varnish after 
 successive intervals of drying time. 
 
 TABLE 14 
 
 (All readings represent the time in seconds for a reduction in the amplitude 
 of the swinging beam from 45 degrees to 22.5 degrees of arc.) 
 
 . After one After two After five 
 Varnish . day’s drying days’ drying days’ drying 
 
 Spar 133.5 159.6 226.2 
 132.1 157.0 199.0 
 
 132.4 163.6 201.2 
 
 130.2 156.0 205.2 
 
 128.6 163.4 205.0 
 
 Av. 131.4 Av. 159.9 Av. 208:3 
 
 Floor 129.8 169.2 205.0 
 141.6 177.6 225.0 
 
 141.6 182.4 221.2 
 
 150.0 172.8 214.6 
 
 139.0 170.0 195.0 
 
 Av. 140.4 Av. 174.4 Av. 213.4 
 
 Rubbing 227.8 259.6 264.8 
 223.0 246.2 234.6 
 
 228.4 243.6 283.6 
 
 226.0 254.2 277.8 
 
 221.8 249.2 283.0 
 
 Av. 225.4 Av. 250.6 Av. 268.8 
 
 The general method for making swinging beam measure- 
 ments has been described above. There are certain additional 
 details to be noted in the use of the beam on varnish films. 
 With relatively soft films (such as a Spar varnish) it is neces- 
 sary to clean the ball-bearing surfaces with ether, as already 
 described, after each separate measurement on different por- 
 tions of the film. Care should be taken to remove any dust 
 either on the ball surfaces or on the varnish film with a fine 
 camel’s hair brush. In the case of very soft films the damping 
 of the beam’s swing will be very rapid so that there may be 
 difficulty in measuring with precision the time interval be- 
 tween the amplitude of 45° and 22.5° of swing. The operator 
 in such cases must approximate this reading as closely as 
 possible. It may be found advisable to dispense with the stop 
 watch and count the swings, estimating fractions of a swing 
 as frequently done with an analytical balance. 
 
 In Fig. 27 the swinging beam factors are plotted for seven 
 different varnishes after periods of drying. The shellac var- 
 
80 Hardness and Abrasion Resistance 
 
 nish was made from ‘‘D. C.’’ orange flake shellac and 95 per 
 cent denatured alcohol and contained 35 per cent of non-vola- 
 tile matter. Varnishes numbered from 1 to 6, inclusively, 
 were commercial products from a large varnish manufacturer 
 and described as follows: 
 
 #1 ‘‘Congo-China Wood oil polishing and rubbing varnish. ”’ 
 
 t2 “‘Same as tl, but more elastic. 
 
 #3 ‘‘Hardened rosin-China wood oil general utility var- 
 nish.’’ 
 
 #4 ‘‘Fossil gum-China wood oil floor varnish.’’ 
 
 t5 ‘‘ Auto finishing varnish.’’ 
 
 t6 ‘‘Waterproof ester gum-China wood oil Spar varnish.”’ 
 Lo FIGURE 27 
 
 COMPARATIVE OATA 
 ON DIFFERENT VARNISH FILMS. 
 
 ) SHELLAC 
 <a VARNISH #1 
 ° P 
 
 Ss 
 L-) 
 
 S 
 ap 
 
 BLAM LMT OR 
 
 VARN/SH #2 
 06 VARNISH #5 
 #4 
 S VARNISH 
 BOF 
 N VARNISH #6 
 Sos 
 ° 
 N 
 05 
 NS 0 
 * 
 Ley ya ee. VARNISH #.&- 
 .s 
 
 a 
 
 / z 5 Fo F 6 7. & 9 
 TIME OF DRYING /N OAVS 
 
 It is believed that a practical varnish man from the above 
 description would say that after drying for a week the shellac 
 would be the ‘hardest, ’? varnish No. 1 next in hardness, var- 
 nish No. 2 next, varnish No. 5 softest, and the other three 
 
 varnishes har der than 5 and softer than 2. Fig. 27 places the 
 varnishes in this order. 
 
Hardness and Abrasion Resistance 81 
 a 
 Attention is drawn to the obvious need of temperature and 
 humidity control of varnish films in any study of their rela- 
 tive hardness. It is intended that these factors shall be con- 
 trolled in work planned for the near future. The effect of 
 varying the thickness of a varnish film should also be studied. 
 The swinging beam was designed primarily for the study of 
 varnish films, but from some preliminary experiments (the 
 data are not shown) it may be possible to adapt this device 
 to the study of the relative hardness of varnish resins, either 
 in their natural or their ‘‘run’’ condition. In such work it is 
 necessary to produce on the resin specimen a polished plane 
 surface. 
 
 Preparation of Films for Hardness.—In working with the 
 Walker-Steele swinging beam, the writer has experimented 
 upon films formed upon various types of surfaces. In the 
 first experiments, the varnishes were applied to wood panels 
 in three-coat work. After drying the hardness was determined 
 with a swinging beam. This method was faulty, inasmuch as 
 the wood panels were not absolutely smooth, and the results 
 therefore were not concordant. In subsequent tests, glass 
 plates were used, the varnishes being flowed and drained in a 
 vertical position. The results obtained were not relative, due 
 to the fact that. the thickness of the films varied to a great 
 extent. It was recognized that thin films upon a hard surface 
 would naturally show a very much greater hardness with the 
 swinging beam apparatus than thick films upon the same type 
 of surface. In a further series of tests, specimens of glass 
 about 5 cm. square were selected. Upon these were spread 
 with a pipette 14 ce. of varnish. They were allowed to flow 
 out and cover the entire plate. The flowing operation was 
 aided with the end of the pipette, and none of the varnish 
 was allowed to flow off the plate. Difficultv, however, was 
 experienced in getting good films. In the final series of experi: 
 ments, microscope slides were used. An excess of the varnish 
 was placed upon these slides and spun for one minute at 300 
 R. P. M. upon the apparatus described on page 108. This 
 method produced smooth, even films of more relative thick- 
 ness than any other method experimented with. The viscosity 
 of the varnish must be taken into consideration, and if the 
 directions on page 108 are followed, films of uniform thickness 
 for hardness comparisons may be obtained. In carrying on 
 
82 Hardness and Abrasion Resistance 
 
 this work, the apparatus must be kept in a glass cabinet and 
 the varnished panels should be placed in the cabinet for a 
 period of time before test so that they will all be brought to 
 the same temperature and tested under practically the same 
 degree of humidity. This apparatus will give much more 
 concordant results if kept in a room maintained at a standard 
 temperature and humidity, such as is deseribed on page 131. 
 
 The effect of moisture in reducing the hardness of varnishes 
 is quite apparent from the results of some tests which were 
 recently made. After the panels were dried for a period of 
 four days, the ends were immersed in water for a period of 
 18 hours. Immediately after removal from the water, the 
 films were pressed to dryness with absorbent filter paper for 
 30 seconds, and the harness again determined. The per cent 
 loss of hardness, due to the water treatment, is presented 
 below: 
 
 TABLE 15.—Hardness 
 
 Swingitig Beam-Time in Seconds 
 
 Per cent 
 Film After loss due 
 thickness water to water 
 Varnish in Microns 1day 4 days treatment absorption 
 Be Ss it ice ed 34 107 173 101 42 
 Pare e ig 155 210 120 43 
 Ais A. 3 94 194 104 46 
 bed ae 20 ewe 191 411. 42. 
 I. G. ee hyd 30 177 239 137 43 
 ate 24 170. 229 137 40 
 ES War saeer 26 188 Pee | 120 49 
 WARE Ae ne 2 20 52 169 85 50 
 
 Pfund Hardness Meter.—Doubtless one of the most satis- 
 factory instruments for determining the hardness of varnishes 
 
 FIGURE 28 
 Diagram of Pfund Hardness Meter. 
 
 > 
 of 
 e 
 
 oe ne 
 
H ardness and Abrasion Resistance 83 
 
 and lacquers is that recently developed by Pfund. This type 
 of apparatus has been in use for over two years in one large 
 plant laboratory, and has proved thoroughly reliable for all 
 types of surfaces. Even on those surfaces in which the ‘‘top 
 tack’’ exists, this apparatus gives results which parallel the 
 findings of practical varnish men using the finger nail test. 
 The apparatus is described below by Dr. Pfund: 
 
 The general disposition of the apparatus is evident from 
 Fig. 28. A brass beam AA is pivoted at P and is supplied 
 with a counter-weight at W, which serves to balance the beam 
 in the absence of the weights M, M.. Impression on the var- 
 nish film V is made by means of a circular cylinder of ecrystal- 
 line quartz C of 14-inch diameter. The lower surface is accu- 
 rately ground and polished to hemispherical form while the 
 upper, flat surface is inclined to the horizontal by 4°. For 
 purposes of viewing, a piece of clear glass is mounted at G so 
 that a horizontal beam of light (perpendicular to the position 
 shown) may be directed downward through the quartz cyl- 
 inder where reflection takes place at the hemispherical surface. 
 The returning beam enters the microscope 0—the character of 
 the phenomenon under observation being shown in the insert 
 of Fig. 28. This illuminating device may, of course, be replaced 
 by the more compact vertical illuminator attachment for 
 microscopes. The diameter of the circle of contact between 
 the hemispherical surface C and the varnish film is measured 
 with a micrometer eye-piece of magnification 10 x. The actual 
 combination used is a Leitz objective No. 2 and the above 
 micrometer eye-piece. This combination yields a linear mag- 
 nification of 70 diameters. 
 
 Instead of measuring the diameter of the circle of contact 
 for a constant load M it has been found that a much greater 
 dispersion of results could be obtained by varying the load 
 until a cirele of fixed and predetermined diameter was pro- 
 duced. The actual diameter agreed upon was three divisions 
 in the micrometer eye-piece. Rather than find the exact load 
 required, it was found more expedient to put on loads yield- 
 ing diameters, respectively, too small and too great. By 
 recording both loads and diameters it was possible to deter- 
 mine the exact load by simple interpolation. For very hard 
 surfaces it was found that the necessary loads become exces- 
 sive. Consequently, it is recommended that, for such mate- 
 rials, a hemispherical surface of 14-inch diameter be employed. 
 
84 Hardness and Abrasion Resistance 
 
 Since the speed of drying and, therefore, the hardness, is 
 dependent to a marked degree upon the film thickness, it has 
 been found necessary to produce films of constant thickness 
 by the spinning dise method of Walker and Thompson.* In 
 most cases a speed of 450 R. P. M. yielded a satisfactory film. 
 
 Some results obtained for characteristic materials after 
 various intervals of drying are given below. The values re- 
 corded are the load M (Fig. 1) necessary to produce the circle 
 of fixed diameter: 
 
 6hrs. 24hrs. 48 hrs. 1 week 
 Oil Vehicle (no gum)........... 6.4 10.6 12.4 
 Black Varnish Enamel.:........ 13.0 22.0 43.0 
 Bpar “VAINISh! oa oles toe ee 220.0 440.0 650.0 
 Black Nitrocellulose Enamel..... 930 grs. 1060.0 1090.0 1375.0 
 Clear Nitrocellulose Lacquer... .. 2285.0 2450.0 2685.0 
 
 These results require no comment. It must be pointed out, 
 however, that such determinations have meaning only when 
 drying and subsequent measurements are carried out in a 
 ‘constant temperature and humidity room.”’ 
 
 ABRASION RESISTANCE. 
 
 The apparatus which the writer has used for this purpose 
 for over twenty years in shown in Fig. 29. It consists of a 
 glass tube about six feet long, having an internal bore of 7/8 
 inch. This is supported in an upright position over a dish 
 holding the panel to be tested, at an angle of 45° to the vertical. 
 The abrasive material, consisting of No. 50 emery powder, 
 is dropped through the tube through a funnel having a bore 
 of 5 mm. When the emery reaches the bottom of the long 
 tube, it scatters itself, to strike a surface on the panel about 
 an inch in diameter. The emery is constantly poured in until 
 the paint coating has worn away, disclosing the bare wood 
 or metal. The weight in pounds of emery powder to cause 
 disruption of the coating is recorded and reported as the 
 measure of abrasion resistance. The test has proved useful 
 not only on freshly dried and hardened coatings but also upon 
 coatings which have been exposed to the weather for several 
 months. Paints, for instance, which chalk rapidly usually 
 form soft surfaces, whereas those which remain hard gener- 
 ally show a high degree of resistance to abrasion. For experl- 
 mental work in the laboratory, the writer has used tin panels 
 
 *Walker and Thompson—Proec, Am. Soc. Testing Mat. (1922), p. 465. 
 
 i Asmat te: 
 
Hardness and Abrasion Resistance 
 
 --——40 
 
 FiIGuRE 29—Gardner Abrasion Test. 
 
86 Hardness and Abrasion Resistance 
 
 coated with very thin films of lithographic ink, usually in red. 
 Over this colored surface, clear or pigmented products are 
 poured or spun to films of the desired thickness. After hard- 
 ening, they are tested for abrasion resistance. The underly- 
 ing color shows a distinct contrast when the emery has abraded 
 the coating down to the colored ink. 
 
 Abrasion Resistance Test of Arsem.—<A testing device 
 called the Abrasiometer, for measuring the abrasion resistance 
 of varnish films, and which uses numerical values, reproducible 
 to 10 per cent or less, has recently been devised by W. C. Arsem 
 and originally described in the Scientific Section Circular No. 
 2944. A brief description of the apparatus by Arsem, together 
 with a chart of some of the results obtained, is given below. 
 
 500 
 
 ABRASION RESISTANCE IN GRAMS 
 
 Z00 
 
 }oO 
 
 FIGURE 30 
 
 Per cent of Gel-Forming Ingredient, by volume. A—Special Bodied Linseed 
 Oil. B—Bodied China Wood Oil. C—Cellulose Nitrate. 
 
Hardness and Abrasion Resistance 87 
 
 The apparatus used in the work consists of a small steel 
 ball-bearing 3/16-inch diameter mounted go that a range of 
 pressures can be applied to it while it is being moved over 
 the surface to be tested. In the simplest form of the apparatus, 
 the steel ball is mounted at the end of a pointed wooden rod 
 fastened to the right-hand pan of a laboratory trip scale with 
 the ball end down, and a counterpoise on the other pan. 
 
 In testing a varnish film, the test plate is placed on the sup- 
 port and moved about under the steel ball, gradually increas- 
 ing the weights, until a definite barely visible scratch is pro- 
 duced. Several further tests are then made, using weights 
 both greater and less than the first approximate value, until 
 the weight which will just produce a scratch is found. With 
 reasonable care, on a film of uniform thickness and degree of 
 dryness, the critical pressure can be determined to within 5 
 to 10 per cent. 
 
 Since the abrasion resistance of a given sample will depend 
 on the degree of dryness, and hence on the initial thickness, it 
 is important that uniformity in the thickness of test films be 
 secured. 
 
 If varnish is flowed on a flat plate and drained off by stand- 
 ing the plate vertically, it is easy with this device to detect a 
 variation in resistance from top to bottom, especially during 
 the early stages of drying. 
 
 Parlin Abrasion Testing Machine.—The type of abrasion 
 testing machine used at the du Pont lacquer plant at Parlin, 
 N. J., for determining the abrasion resistance of films is shown 
 in Fig. 31. 
 
 It consists essentially of a fixed base equipped with an ad- 
 Justable clamp for holding the panel. The carriage, through 
 which passes the rubbing tool, is motor driven from behind by 
 a rod or piston which moves it back and forth in a horizontal 
 plane. <A counter is also fastened to the carriage which records 
 the number of oscillations made in rubbing through the lac- 
 quer. The tool used is tipped with a rubber or any desired 
 mild abrasive. By placing shot in the hollow cylinder at the 
 top of the tool, the severity of the test can be varied. 
 
 Method of Testing.—To test a lacquer, clamp the panel in the 
 position shown, insert the tool in the carriage and connect the 
 motor. With the carriage at one extreme of its path, start 
 
88 Hardness and Abrasion Resistance | | 
 
 \ 
 : 
 ‘ 
 4 
 J 
 ; 
 
 FIGURE 51 
 
 Parlin Abrasion Testing Device. 
 
 the oscillation. When the lacquer has been rubbed through, 
 which may be readily seen by the appearance of the panel, note 
 the number of oscillations made and disconnect the motor. 
 Comparisons may be made as in the previous tests, by using 
 coatings of the same thickness. 
 
CHAPTER IV 
 
 GLOSS MEASUREMENTS ON PAINTS. 
 
 It is important that instruments be available for measuring 
 the gloss of paints. One such instrument recently developed 
 .is known as the Ingersoll glarimeter. Considerable work has 
 been done with this instrument by E. F. Hickson of the Paint 
 and Varnish Section of the U. S. Bureau of Standards. His 
 results are presented below in the form of a paper originally 
 prepared for Scientific Section Circular No. 307. 
 
 ‘‘Flat,’’ ‘“egeshell,’’ and ‘‘gloss’’ are terms commonly used 
 in describing the surface of a paint coat. Whitewash, flat 
 
 FIGuRE 32 
 
 Ingersoll Glarimeter Resting Upon Disc Coated with White Gloss Paint. 
 
 wall paint, and japan color coats are examples of the so-called 
 ‘*flat’’ finishes. ‘‘Egegshell’’ finishes are possessed by many 
 oil paints, pigmented lacquers, and wall finishes. The best 
 grades of enamels are examples of highly glossy finishes. 
 
90 Gloss Measurements 
  ——————— 
 
 Other than by Nelson* little mention has been made of the 
 use of the glarimeter in connection with paint and varnish. 
 It is the purpose of this paper to show some of the applications 
 and limitations of the glarimeter as an instrument for measur- 
 ing the gloss of paints. 
 
 Ingersoll Glarimeter—This instrument was developed by 
 L. R. Ingersoll, of the University of Wisconsin, in connection 
 with research work on paper problems for the Forest Products 
 Laboratory. It was first described by him in 1914,+ and has 
 been further described in other places. Its chief use for 
 several years has been in the paper industry. 
 
 The glarimeter used in this work is of the latest type,t and 
 is shown in Fig. 32. It does not measure gloss directly, but 
 gives the ratio of polarized to total light in a certain direction 
 from the sample, this ratio being taken as the measure of the 
 gloss. The instrument is so built as to allow a beam of hght 
 to fall onto the test surface at an angle of 571% degrees, and to 
 be reflected into a polarimeter at the same angle. Gloss is 
 expressed in angular degrees on an arbitrary seale reading 
 from 10 to 60, and is determined by moving the index until the 
 two parts of the bifield are just matched in light intensity. 
 The gloss in degrees may be converted into per cent gloss by 
 Ingersoll’s formula: 
 
 Per cent gloss = 100 X cosine 2 X (60° —scale setting). 
 
 Method of Making Tests——The most satisfactory method for 
 preparing films for gloss measurements consists in whirling 
 the paint on a glass plate{ and letting the coat dry in a well- 
 lighted laboratory for not less than 48 hours (in the lightest 
 part of the laboratory). If the paint hides poorly, additional 
 coats are spun on the plate until any effect of the background 
 is eliminated. The gloss is then measured in several places 
 but preferably at the same thickness, five readings being 
 taken in each place, and the mean of the results recorded. 
 Readings may also be taken on brushed films, but if the brush- 
 
 *Nelson & Schmutz, Proceedings, A. S. T. M., Vol. 24, Part II, p. 923 (1924). 
 
 j Electrical World, Vol. 68, pp. 645-647 (March, 1914). For further references 
 see sunrgds No. 100, Central Scientific Company, 460 E. Ohio Street, Chi- 
 eago, Ill. . 
 
 tCentral Scientfic Co., Chicago, Ill. 
 
 qP. H. Walker and J. G. Thompson, “Some Physical Properties of Paints,” 
 Proceedings, A. 8. T.-M. Vol. 22, Part. II, p. 465 (1922), 
 
 ae vere neeaye 
 
Gloss Measurements 91 
 
 marks show, the readings taken parallel with these marks will 
 be slightly higher than those taken across them. The whirled 
 films are smoother than the brushed films. Table 16 giv 
 readings by this method on typical white paints and in two 
 instances results of whirled films are compared with brushed 
 films of linseed oil paints. It is noted that gloss readings on 
 
 these whirled films are shghtly higher than those on the 
 brushed films. 
 
 es some 
 
 TABLE 16 
 GLoss MEASUREMENTS ON VARIOUS WHITE ParInts 
 Gloss 
 1—Lead-zine-linseed oil paint Degrees Per cent 
 MORN Re ee a Bode nce cn dcke. 50.8 95.0 
 Been coat: j0D....... 236s. s.c.... 50.1 94.2 
 
 2—Another lead-zine paint 
 Whirled film 
 
 RETR oor ic. s, ass duc ot g Ghee kee CE raw eye 96.0 
 Oe, ss eee cee cece n., a 95.5 
 
 SpE MREMORTT Sia vey if one's he gO -s a koe how os 51.2 95.4 
 4—Inside “gloss” wall paint 
 
 re ici. Soc cat eee edie cne. 52.5 96.9 
 5—White enamel 
 
 ee ls oe bob cela ole. 54.0 97.8 
 6—Inside “flat” wall paint 
 
 RE Re ee ee er ee 22.0 24.0 
 (—“Eggshell” wall paint 
 
 Rh EM ee ery Oh ei ed ee oes 40.0 76.0 — 
 ee eR oe el 18.0 10.0 
 
 Table 17 shows the precision obtained by the same operator 
 im measuring the gloss of whirled films of two white linseed- 
 oil paints. 
 
 TABLE 17 
 
 PRECISION OBTAINED ON Two WHIRLED PAINTS, 
 READINGS OF GLOSS IN DEGREES 
 
 Paint 4H Paint 4D 
 50.2 a) a 
 50.8 51.8 
 50.8 51.6 
 50.8 Di.G 
 51.0 51.9 
 51.0 51.5 
 50.5 51.9 
 50.9 51.6 
 50.8 51.8 
 51.0 
 
 —- Mean BLT (96.0% gloss) 
 Mean 50.8 (95.0% gloss) 
 
 Table 18 shows the interesting effect of excessively brush- 
 ing a flat white wall paint. Flat wall paints should be flowed 
 on with the brush as the effect of excessive brushing is to de- 
 velop gloss spots. The table also shows the precision obtained 
 
92 Gloss Measurements 
 
 by different operators on the same brushed flat white wall 
 paint. The excessively brushed paint in Table 18 was notice- 
 ably more glossy to the eye than the same paint when brushed 
 
 as little as possible. . 
 TABLE 18 
 EFFECT ON GLOSS OF EXCESSIVELY BRUSHING A “FLAT” WALL PAIntT 
 PAINT BRUSHED AS LITTLE AS POSSIBLE 
 
 Operator A Operator B 7 
 degrees degrees 
 45s ee ee PEPER EL 29.0 
 BOB v's eas oe 66 4 0 ens dipiaiaia a ohe oe nn 30.0 
 4 eC LM 29.5 
 1 Pr a 29.5 
 Mean 29.7 (49.0% gloss) Mean 29.5 (48.5% gloss) 
 PAINT BRUSHED EXCESSIVELY . 
 Operator A Operator B 
 degrees degrees 
 B25 ove leces vee ce euas aan oe ee 32.0 
 BOQ. so cin oo « win 94 9 a. aopib ine gh clas 32.5 
 BOB eka a weno kvons ele we ely a ele ene eee a 33.0 
 Mean 382.7 (58.0% gloss) Mean 82.5 (57.5% gloss) 
 
 Loss of Gloss of Paints on Exposure-—Generally the first 
 signs of weathering of outside white paints is loss of gloss. 
 
 ‘ TABLE 19 
 Loss oF GLOSS OF OUTSIDE WHITE PAINTS EXPosED ON Woop 
 Percentage of gloss after 
 
 Panel i << <<< nny UDG OF 
 No. 48 hours i1month 2months 8months 5months paint 
 Lea ery cg Woe ets 92.0 86.5 83.5 70.0 63.0 a 
 Bis gis 90.0 7.5 SL 72.5 66.5 a 
 Le ee aes Pte 2 90.0 76.0 56.0 40.0 30.0 b 
 4 ca sins dee 92.0 81.5 70.0 38.5 38.0 b 
 Bis ous oS oy eee 90.0 87.5 77.0 65.0 50.0 a 
 SEF Cente 2 ees 90.0 80.5 T4.5 70.0 43.5 a 
 Bhai dteten ois tap ates 90.0 80.5 76.0 38.5 28.0 b 
 Sil aca eae 90.0 80.5 51.5 37.0 31.5 b 
 i caib gasket aes 90.0 2.5 80.0 71.5 56.0 a 
 LG or ah inte s aa 89.0 80.5 80.0 70.0 50.0 a 
 Te wee cee 90.5 70.0 51.5 40.0 35.0 b 
 8 he ue tr Ween 88.5 79.5 T4.5 62.5 48.0 a 
 DED sieatee ee eae ee 91.5 77.0 50.0 38.5 PEA b 
 ie ere Poet Pr merc te 80.5 74.5 66.5 50.0 a 
 Reb es ad aie ee 91.5 83.5 67.5 35.0 33.5 b 
 Gig eis ia tool men 90.0 83.5 62.5 40.0 35.0 b 
 AS wenn Gite eee 89.0 83.5 79.5 67.5 59.0 a 
 EB Borie he, 2 aba my 89.0 84.5 77.0 65.0 57.5 a 
 UA hed irae SSR 90.0 81.5 51.5 37.0 38.5 b 
 Ad aes Wee s cee ye 89.0 77.0 50.0 35.0 ab eesti b 
 CWE SP ee Se US $3.5 86.5 76.0 65.0 51.5 a 
 BS Aenea ee aie 90.0 85.5 T4.5 64.0 ‘51.5 a 
 Ud Cotes FFLkS ahd tees 91.5 78.0 43.0 37.0 34.0 b 
 BAS Bes © oieste ctdatok 90.5 76.0 62.5 43.5 38.5 b 
 BE NE wie Wis Ong a ee ee 88.0 85.5 74.5 69.0 54.5 a 
 v5 Bae Ree ee PB 90.0 87.5 77.0 67.5 51.5 a 
 
 r 
 { 
 3 
 | 
 j 
 
 4 
 ‘ 
 
 ae eA ee 
 
Gloss Measurements 93 
 
 In exposure tests this is often recorded by words such as 
 peed, = air, ‘*poor,’’ ‘gloss nearly gone,’’ ete. The appli- 
 eation of the glarimeter to measuring and recording in num- 
 hers the loss of gloss of exposed white paints is shown in Table 
 19. These paints were all outside white-linseed oil paints. 
 They were applied by brushing three coats on new wood. The 
 panels were exposed vertically facing south. All readings in 
 this table are expressed in per cent gloss. 
 
 The paints marked ‘‘a’’ in Table 19 were lead-zine paints, 
 while those marked ‘‘h’’ were straight white lead. The white 
 lead paints showed a greater loss of gloss at the end of the 
 five months of exposure. It should be noted that in panel No. 
 19 a higher gloss figure was obtained after the fifth month 
 than at the end of the third month. This is the point where 
 some of the white lead paints (for instance No. 4) began to 
 pick up dirt, and after the sixth month a number of the white 
 lead paints gave higher gloss readings than those of the pre- 
 vious month. The explanation for this is probably that after 
 the first rapid loss of gloss on the white lead paints began to 
 pick up dirt. This dirt had the effect of decreasing the bright- 
 ness of the paint, thus giving a higher gloss reading by the 
 instrument. The effect of brightness on gloss as measured 
 by the glarimeter will be considered later in this paper. 7 
 
 If the pigment concentration is kept constant, the effect of 
 adding linseed oil to the vehicle of a paint is to increase its 
 gloss. This is shown in Table 20 for four kinds of white lin- 
 seed oil paints. 
 
 TABLE 20 
 
 EFFECT ON GLOSS OF ADDITIONAL OIL IN VEHICLES OF OUTSIDE 
 WHITE PAINTS 
 
 Gloss Oil in 
 
 ————_————, Pigment vehicle 
 
 Paint Degrees Percent percent per cent 
 JSS ees Se er 47.3 90.2 60 66 
 ONO Veo E08 ne a 49.4 93.2 60 76 
 AOL aly a eg ea a 49.5 93.5 60 85 
 (Paint 2 contained 50 per cent lithopone and 50 per cent zinc 
 
 oxide. ) 
 
 LS See ig ge 48.5 92.0 60 66 
 Lee a, AN SE ea 49.8 93.8 60 76 
 a, nye ke eK oc 50.1 94.1 GO 85 
 
 (Paint 1 contained 50 per cent titanium pigment and 50 per 
 cent zine oxide.) 
 
 cee ee a 48.7 92.3 59.5 66 
 “os Se ae 50.2 94.2 59.5 76 
 Reet MGs rai sha dlv's.3°s 80 ch cca 5 50.9 95.0 59.5 85 
 
94 Gloss Measurements 
 
 (Paint 3 contained 30 per cent zine oxide and 70 per cent. 
 titanium pigment.) 
 
 HEAD iy se dae Sete Reale en ie eee go 49.3 93.1 61 66 
 BS as ie a aes Dele a ek ON sere 50.2 94.2 61 76 
 BG Pile cen ao elats. Ge eee Wee OR Ceteie o1.4 95.6 61 85 
 
 (Paint 4 contained 50 per cent zine oxide and 50 per cent white 
 lead.) 
 If the oil in the vehicle is kept constant, increase in pigment 
 concentration tends to decrease the gloss of a paint. This is 
 shown in paint 5, a white lead paint. 
 
 Gloss Oil in 
 ——__————, Pigment vehicle 
 Paint Degrees Percent percent percent 
 sf: RDA eRe Ome at cama ee hacer Mp ol oie AG, 50.8 94.9 70.3 96 
 SSIES iva thine ie ve sins See ese aie ee 50.9 95.0 68.3 96 
 Rios laracahe ie eae opp ows baat eceeeal eae ee eae 51.3 95.5 64.6 96 
 
 In connection with the gloss of paint 5, it is interesting to note 
 that 5C is now, after nearly two years of outdoor exposure, the 
 darkest or has picked up the most dirt. Paint 5A is the whitest 
 or cleanest. 
 
 Gloss of Colored Paints.—Darkening of a color (including 
 white) increases the gloss readings on the glarimeter. This 
 darkening reduces the amount of diffusely reflected light, 
 while altering to only a minor degree the specularly reflected 
 portion. Therefore it is important to point out that results 
 obtained by the glarimeter are influenced by the color and 
 brightness of the paint. For example, two surfaces of. glass, 
 one white and the other black, both ground ‘‘semiflat’’ in the 
 same manner gave the following gloss readings: 
 
 White surtate- (v2.5. .oae ees 42 degrees (80.5 per cent gloss) 
 
 Black. surface: sse9 toe 2s ae eee 55 degrees (98.5 per cent gloss) 
 A clear glass plate was then placed over these surfaces and 
 gloss reading taken: 
 
 White .......c.ccsceccsvce+ +. 040 GepTees (95.6 per cen tmaee 
 
 Black «so. eo ee ee ..09.0 degrees (99.8 per cent gloss) 
 Again, a coat of ‘‘flat’’ drop black in japan gave a reading of 
 46 degrees (88 per cent), while a ‘‘flat’’ white wall paint that 
 
 looked as ‘‘flat’’ as the black japan gave a reading of 22 de- 
 
 grees (24 per cent). Black enamels that varied considerably in 
 gloss to the eye gave the same readings with the glarimeter. 
 A coat of olive drab paint with a fairly dull (eggshell) finish 
 gave a gloss reading of 55 degrees (98.2 per cent) which in 
 
 the case of white paints indicates an extremely high gloss. 
 
 a ee 
 
 a Eee ee 
 
 we, so at ee ka ‘ 
 es. a, ee ee Ok er 
 
Gloss Measurements 95 
 
 Effect of Brightness on Gloss.—Evidently, from what has 
 Just been said, measurements of the same gloss taken on sur- 
 faces varying in brightness are not comparable. <A series of 
 grays was prepared from a ‘‘flat’’ white wall paint by the 
 addition of very small amounts of lampblack. Each paint was 
 flowed on a piece of glass so as to obtain the same thickness, 
 and then allowed to dry for 24 hours. In all cases the paints 
 dried to smooth, ‘‘flat’’ surfaces in about two hours. Gloss 
 readings were taken by the glarimeter, and brightness read- 
 ings were taken by a Martens photometer (assuming mag 
 nesium carbonate block = 100). <A spherical illumination 
 chamber designed by Priest was used. With this appara- 
 tus the sample and reference white are diffusely illuminated 
 and the reflection is measured normal to the surfaces (both 
 conditions approximate only). A description of the use of the 
 Martens photometer as well as an illustration of this illumina- 
 tion chamber is given in Bureau of Standards Technologie 
 Paper No. 306, ‘‘A Photometric Method for Measuring the 
 Hiding Power of Paints.’’ Also see page 27. The results 
 
 obtained were as follows: 
 Gloss readings 
 
 ——_——"_ Brightness 
 
 " Degrees Per cent per cent 
 Pree ILE DOINE. 5. -siew sos idee os ss 24.0 30 84.4 
 “Flat” white paint plus carbon........ 27.5 42 62.0 
 ss ib rh ry Dts caaie ee 6 33.0 58.9 28.5 
 s . a x 2 gC eee eure 36.5 68 15.7 
 “ i fe cs enh athidr ve Seto) (2 7.6 
 
 Thus by decreasing the brightness, the gloss readings in- 
 creased, although to the eye there was no appreciable differ- 
 ence 1n gloss. 
 
 Conclusions.—The glarimeter, when properly used, gives 
 readings that can be checked generally within a few tenths of 
 a degree by different operators, and the instrument serves a 
 very practical purpose. In the case of white paints where the 
 total reflection remains about constant, the only variable being 
 the finish, gloss readings are in the proper direction as seen by 
 the eye. The same would hold true in the case of grays or 
 eolors if the total reflection were kept constant. When the 
 total reflection is changed, as in the gray series, the glarimeter 
 does not take this reflection change into account and therefore 
 the readings do not compare with what the eye sees. Colored 
 surfaces act in the same manner. On very glossy enamels 
 
96 | Gloss Measurements 
 
 (black or white) the glarimeter does not pick out the fine 
 distinctions of gloss visible to the unaided eye. The paint 
 industry is still in need of an instrument that will give values 
 for gloss which are not influenced by color and brightness. 
 Such an instrument should also be as sensitive as the unaided 
 eye in picking out fine distinctions on very glossy enamels. 
 For testing the gloss of clear varnishes, Pfund* claims to have 
 developed such an instrument. 
 
 *A.H. Pfund, ‘Tests for Hardness, Gloss, Color and Leveling of Varnishes,” 
 Proceedings, American Society for Testing Materials, Vol. XXV, Part II. p. 
 392 (1925). 
 
 4 
 | 
 . 
 
CHAPTER V 
 
 TENSILE STRENGTH AND ELONGATION 
 
 An apparatus recently devised by the writer and H. GC. Parks 
 to determine the tensile strength and elongation of paint, var- 
 nish and lacquer films is described herewith. This apparatus, 
 which is small in size, compact, and neat in appearance, has 
 recently been adopted by several testing laboratories. 
 
 Fig. 33.—View of Gardner-Parks Film Tester on Laboratory table. Note 
 white test piece of film near top of column, Film thickness gauge at right. 
 
 One man can operate it successfully. It is driven by a 
 small electric motor which plugs directly into any electric light 
 socket. The photograph shows the size of the apparatus in 
 comparison with that of an operator. The drawing indicates 
 how the apparatus was constructed. It will be noted that two 
 springs are provided, one for paint and varnish films (ranging 
 
98 Tensile Strength and Elongation 
 
 from 0 to 500 grams) and one for lacquer films (ranging from 
 0 to 2,500 grams). Both springs are carefully calibrated. It 
 will also be noted that the scale for determining the percentage 
 of elongation ranges from 0 to 100 degrees for any type of film. 
 
 In the photograph, at the right, there is shown a small film 
 gauge used to determine the thickness of the film tested, the 
 dial of the gauge reading in metric equivalents. The results 
 obtained upon testing are always calculated upon the basis of 
 the load in kilograms per square centimeter, thus taking care 
 of films of varying thickness. _ 
 
 Description of Instrument.—In Fig. 34 (1) is the tubular col- 
 umn, (2) a bell-shaped housing, and (3) the base proper which, 
 together form the body of the mstrument; (4) is the elevating 
 screw which is driven by the sheave wheel (5) through the 
 worm (6) and worm wheel (7), the elongated split hub of 
 which (8) forms a friction nut on the elevating screw; (9) is a 
 handwheel, (10) a yoke which carries the guide rods (11) (only 
 one of which appears in the drawings), which slide vertically 
 in the yoke (12); also the upper specimen grip (13) and the 
 lockserew (14); (15) is a tight collar on the screw, (16) 
 the lower specimen grip, (17) a tension rod which has a loose 
 sliding placed in the hole in plate (18) fastened to ‘bracket 
 (19), which bracket, secured to the tubular column, has tapered 
 raceways in which steel balls (20) frictionally engage the ten- 
 sion rod; (21) is a latch by means of which the balls may be 
 disengaged, (22) is a tension spring which carries at its upper 
 end the screwed bracket (23) forming a pointer which reads 
 on the double scale (24); (25) is the lower end of tension 
 spring which is fastened in the bell housing by the setscrew 
 (26) ; (27) is an extensometer of which the upper pointer (28) 
 is carried by a sliding bar which is adjustable vertically by 
 means of the screw (29) and the compression spring (30), and 
 which carries a scale (31) which is read from the lower pointer 
 (32) attached to a. rack (33), adjustable vertically by a pinion 
 attached to the knurled knob (34). 
 
 Operation of the Instrument.—The lockscrew (14) being 
 loosened and the elevating screw being run all the way down 
 by means of the handwheel, the sheavewheel belted to the 
 motor is caused to rotate, which causes the worm, wormwheel, 
 elevating screw and handwheel to rotate but causes no relative 
 motion of the specimen grips with respect to their distance 
 
99 
 
 Tensile Strength and Elongation 
 
 IN 
 
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 At right—Front Elevation of 
 
 Sectional Side Elevation. 
 
 At left 
 
 o4. 
 
 FIG. 
 
 Apparatus. 
 
100 Tensile Strength and Elongation 
 
 apart. ‘The specimen being clamped in the grips, marked with 
 gauge marks, and the extensometer pointers being set thereto, 
 the lockscrew is tightened, which locks the handwheel and ele- 
 vating screw, causing screw to slip in the friction nut (8) 
 thereby elevating yoke (10) carrying the upper grip. The | 
 specimen is thereby caused to draw up the lower grip, and 
 with it the tension rod and spring, whereby a reading of the 
 load is obtainable at any instant, on the double seales (for 
 which separate tension springs are provided) and also the ex- 
 tension of the specimen, due to said load, which may be read 
 directly in percentage of elongation by proper manipulation 
 of the extensometer pointers, on scale (31). When the spect- 
 men fails, the steel balls (20) lock the tension rod and enable 
 the ultimate load to be read at leisure. | 
 
 Film Preparation.—In preparing films for test upon this 
 apparatus, two methods may be used. The one in use at this 
 laboratory to the greatest extent depends upon the use of mer- 
 curvy coated tin plates. Sheets of tin plate 6” x 12” are lightly 
 rubbed with mereury until the surface is well amalgamated. 
 Excess mercury is rubbed off with a rag. The liquid coating 
 material can be sprayed or flowed upon the surface. After 
 drying, a knife blade is run around the edge of the coated 
 surface to lightly lift the film which is then stripped off in a 
 large sheet the size of the panel. For varnish films, drying 
 over night is allowed. For paint films, drying for two or 
 three days is desirable. For lacquer films, drying for 30 min- 
 utes is usually sufficient. When working with the latter pro- 
 ducts, it is important that the films be stripped not more than 
 an hour after application, otherwise they may dry so hard that 
 stripping may become difficult. After the films are removed, 
 they are placed between sheets of paper and specimens are cut 
 out with test piece die. For this purpose, the specimens are 
 placed upon a board to serve as a background for the impact 
 of the hammer used for forcing the die through the specimen. 
 
 In another method of film preparation, heavy bond paper is 
 used and it is given two coats of flexible glue made by dissolvy- 
 ing 5 parts of glue and 1 part of glycerin in 100 parts of water. 
 Two coats are usually sufficient to fill the paper and give a 
 smooth surface upon which the coating material is applied by 
 one of the means mentioned above. After treating, the coated 
 
Tensile Strength and Elongation 101 
 
 paper is soaked in water for a few minutes until the film be- 
 comes loose. it is then stripped off and placed in clean water 
 to remove any adherent glue. It is then hung up to dry and 
 age before testing. Some results obtained upon lacquer films 
 with this type of apparatus are shown on page 144. 
 
Tensile Strength and Elongation 
 
 102 
 
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CHAPTER VI 
 
 FILM THICKNESS 
 
 Dried Films.—In determining the thickness of dried paint 
 films, the apparatus used in this laboratory is that shown in 
 Fig. 33. It is known as the No. 3-A Dial Upright Gauge,* and 
 is graduated to .QImm. (See lower right hand corner of 
 Fig. 33 on page 97.) The thickness of dried stripped films is 
 measured qui¢kly and with a fair degree of accuracy with this 
 simple device... When measuring the thickness of films in situ, 
 such as those which are dried upon metal panels, the proce- 
 dure is to measure the thickness of the coated panel and then 
 remove a small amount of the coating with a knife to the bare 
 metal. Thickness determinations are then made at this bare 
 spot. The difference between the two determinations gives 
 the thickness of the film resting upon the metal. 
 
 Wet Films.—For determining the thickness of wet paint 
 
 films, this laboratory has used with fairly satisfactory results 
 _ the Pfund paint film gauge. This instrument was developed 
 for the purpose of measuring the thickness of wet paint-films. 
 . Essentially, the instrument consists of a spherical, convex sur- 
 face which is forced through the paint layer. Since the paint 
 is a plastic solid whose ‘‘yield value’’ exceeds the existant 
 capillary forces, the volume of paint originally in a circular 
 dise of section ABCKA is forced into the meniscus AEFGBA. 
 If the diameter (D) of the circular paint-spot is measured, and 
 if the radius of curvature (R) of the convex surface be known, 
 it is found that the thickness (¢) of the original paint-film is 
 given by the relation: 
 
 p 
 
 16R° 
 
 The final form given the instrument is shown in Fig 35. A 
 convex lens L whose lower surface has a radius of curvature of 
 25 em. is mounted in a short tube 7, which slides freely in an 
 outer tube T’,. The compression springs S keep the convex sur- 
 face out of contact with the paint-film until pressure is ap- 
 plied to the top of 71. This instrument is simply rested on a 
 painted surface, and the lens is forced down as far as it will 
 go. Upon releasing the pressure before removing the gauge, 
 
 jess: 
 
 * Made by B. C. Ames Co., Waltham, Mass. 
 
104 Film Thickness 
 
 ———— 
 
 a circular spot is left on the gauge as well as on the painted 
 surface. The diameter of the spot on the gauge is measured 
 
 ee ME in 
 
 (JA RN REDDAEDDSE EES 
 TATVIMINIRRASTADSS 
 TTVIIRIVAA DSS ESD 
 
 SVS IS 3 8S 
 
 Pfund Film Gauge. 
 Mark Left on Painted Surface by Gauge. 
 Scale for Measuring Spot on Gauge Lens. 
 
 to 0.1 of a millimetre. If the spot is elliptical, the mean of the 
 major and minor axes is determined. <A series of readings on 
 at least ten spots, judiciously distributed over a given area, 
 yields a fair value of the average thickness of film. By re- 
 ferring to the table printed below, the thickness of the paint- 
 film in mm. and the number of square feet which would he cov- 
 ered by one gallon of paint may be evaluated at once. 
 
 A number of experiments were carried out to check the ac- 
 curacy of the paint-film gauge. In each case a known mass 
 of paint was spread uniformly over a definite area of plate- 
 glass, and the thickness of film was ealeulated in the usual 
 
Film Thickness ) 105 
 
 manner. Different gauges and thickness of layer were used. 
 The results are briefly presented in the following table: 
 
 I if III 1V 
 Film thickness (by calculation)......... 0.0444 mm. 0.0402 0.0644 0.0638 
 Film thickness (by paint-fllm gauge)... 0.0448 0.0390 0.0652 — 0.0638 
 
 Considering the roughness of the measurements, the agree- 
 ment is surprisingly good. Equally satisfactory results were 
 obtained on varnish films. The differences between the two 
 sets of measurements rarely exceeded 3 per cent. 
 
 Fig. 36 
 Pfund Paint Film Gauge 
 
 For testing the accuracy of this instrument, ideal conditions 
 exist when the paint is grainless and the underlying surface is 
 smooth, flat and non-porous. Using a zinc-oxide linseed-oil 
 paint spread upon plate glass it has been found, as previously 
 noted, that the paint film gauge yields results which are essen- 
 tially correct. However, if the paint is gritty or if the surface 
 to be painted is rough, the paint-film gauge will yield film 
 thicknesses which are too small. Conversely, if the sub-sur- 
 face is soft and yields under the pressure of the convex surface, 
 the evaluated film thickness will come out too large. 
 
 Undoubtedly this instrument will be of great service to the 
 paint experimenter in working on the physical properties of 
 pigments.* Probably its most important application will be 
 
 “Readings on glass made with the Pfund gauge by P. R. Croll, New Jersey 
 Zine Co. Research Laboratories as referred to are 1047, 996, 979, 870 and 
 930 or an average of 964 as against a true spreading rate of 1009 square 
 feet as determined by weight of paint (error 3.5 per cent.) 
 
106 Film Thickness 
 LL 
 
 TABLE 22 
 
 d = Diameter of paint spot on lens (in mm.). 
 t = Thickness of paint film (in mm.). 
 
 d t 
 In mm. Thickness in mm. Sq. ft. per gal. 
 
 Bike oe ee ee 00225 . seen eee 18,088 
 
 he aie RN cate eat oe 00400 . a...) oF ee 10,175 
 
 PSs ag ea ee res 00625... be ee eae 6,512 
 
 ack, oS coe eee one 00900 oo ucccg sae 4,522 
 
 Tic i hea £01225)... ss hee 3,021 
 
 Bes. Ook Ste oe ea 01600 © 0.0: Gihe ae ee 2,543 
 
 ea 2 inp ae ae 02025 03 ck Se 2,009 
 IO Sea a oe 02500 «0°. ss sree eee 1,628 
 Wed or seagate, aera 08025... i. 55 ae eee 1,345 
 PAG Se epepen ee Medan. A .08600.... 53355 ee 1,130 
 IB a ae ee oe O4225 0c ic oe ee 963 
 PS Rat ao ni epee 04900... . os sac 830 
 LUNG sisi c Wc .05625...55.. 5 22 ee 123 
 IOC e eee es ee 06400. v.s% oa ae eee 636 
 17 Se ee OT225.. 2 oe 563 
 ti. Pere reer ot. O8T00..'.. 2 oa eee 502 
 1 es eee .09025 .... ia 5 seen 450 
 DN x5 Rick Oy on -10000.5 oo. 407 
 pdt Peper ene ere tte ey Sy 11025...3. 2.4 369 
 De cok Ak Walaa ee 12100 3. seis ee 336 
 7 EN a Te eg 8220... So a ee 307 
 DAN einen a ee Ae 14400 ...23 6 Sia ee 282 
 BD) 5s he ahaa oe 15625. 5 54520 260 
 2G bai sitet Coen .169002...5 14.245 241 
 OM ine oes eee ‘18226 U5 ote ee pp’ 
 Dc david aN oe 19600 540) 0h ee 207 
 QD wiciese: aoace ieee eee 21025 5.08 eee 193 
 DOs o5 ies soon eee 22500 23 ste eee 180 
 Bei e too pee 20000 . |... + sa ee 158 
 D4 sy wlseckcc a otacataene 2000 is oc 5 cela eee 141 
 DO 5 ea eae ee eeuaee 2400 6s a 125 
 BB: iiss ee ees 36100 3. oo. fae 113 
 
 for gauging the thickness of coatings applied by the spray gun. 
 Sprayed films are apt to be very thick unless the application is 
 properly controlled. (See Table 23.) 
 
 The instrument is apparently accurate to within 25% of the 
 eorrect value when applied to fairly smooth planes. This re- 
 sult was arrived at by the present writer* after several hun- 
 dred tests upon a large number of paints applied to different 
 kinds of surfaces. _ It should, therefore, be of interest to paint- 
 ers. 
 
 Some of the factors which make the instrument not wholly 
 reliable for measuring the thickness of films on exteriors are 
 roughness of wood surfaces, rust spots on metal, slight splint- 
 ers or grain effects on wood, coarse particles in paints that are 
 
 *See Circular 132 of the Scientific Section. 
 
 <e 
 
 es 
 
 aed Vln Pre 
 
 Ce ge Ae ne ee eee 
 
Film Thickness 107 
 a a eee od 
 
 TABLE 23—Measurements with Pfund Gauge on Surface Coated with a Spray 
 Gun and Hand Brush 
 
 Tests on Wood. Tests on Metal. 
 Spreading Spreading 
 Rate Rate 
 Sq. Ft. per Sq. Ft. per 
 Gallon. Gallon. 
 Mill White Primer: 
 Bier ee hc ccc een 868 1093 
 Rr os vc caw cee vce 607 420 
 Mill White Flat: 
 PORTS VANCED et ee. oo va ce ces 192 1107 
 YN os oy ce cr 382 Dot 
 Mill White Gloss: 
 UNG EGY) 8 ee a 1175 980 
 Ue Ue a nr rr 407 352 
 
 Nore :—Sprayed films were quite thick and had excellent hiding properties. 
 Hand-brushed films were thin and more transparent. 
 
 not well ground, and yielding of surfaces under the pressure 
 applied to the instrument. 
 
 A series of tests was also made to determine the actual ratio 
 between spreading rate as calculated by determining the 
 weight of a paint and the number of pounds or gallons applied 
 to a surface, and the spreading rate as determined by the 
 Pfund instrument. The measurements of the Pfund instru- 
 ment were made upon the surfaces directly after the applica- 
 tion of the paint. In these tests dressed lumber that had been 
 primed, and perfectly clean black iron were used. Represen- 
 tative results are given herewith: 
 
 Wood. 
 
 Spreading rate estimated from weight of PAID Appled es ace. ae we 815 
 Be eU err eye URG BRUCE. we so ie od ce esc cc kk ceevcdiccencc. 1175 
 Metal. 
 
 Spreading rate estimated from weight of Haintea polled soe wee Sees 827 
 peer tam VO LONd SAUrC.. yi ese obs occ oo cae lace beck. 1037 
 
 In another series of tests the following results were ob- 
 tained: 
 
 TABLE 24 
 Hand Brushed. 
 Actual Spread- 
 ing Rate Esti- 
 Hand mated from 
 Sprayed. Brushed Weight of 
 Gauge Test. Gauge Test. Paint Applied. 
 Mill White Primer: 
 ELECTS Sa ee a Hep Rase 1088 1160 Bed 
 See ee 925 1001 1073 
 Coen 670 155 885 
 Gloss White: 
 ey eg eels a cw Sw ole 1370 1068 eats 
 NE Me i sie fash one 925 1052 1017 
 
 Re Be se. cS -e onan se 510 686 868 
 
108 Film Thickness 
 
 a 
 In the above tests at least ten measurements were made 
 
 with the Pfund instrument on each test, and the average figure 
 
 used in calculating the thickness of the films. It is of interest 
 
 to note the rather uniform results obtainable in hand-brush 
 
 application, as shown by the measurements below. 
 
 TABLE 25—-Diameter of Spot in Centimeters 
 
 Paint No. 1. Paint. No. 2. Paint No. 3. Paint No. 4. 
 1,25 Rol 1.45 1.30 
 1.30 Re 1.45 1.25 
 E10 90 1.45 pe 4 
 gS bt 90 1.40 Lae 
 1.05 90 1.45 1.20 
 1.05 90 1.40 1.25 
 
 Apparently from the above results, the gauge may either 
 overestimate or underestimate the amount of paint applied. 
 It is believed, however, that the instrument will be found of 
 considerable use in painting work. 
 
 Controlling the Thickness of Films for Testing.—In testing 
 films of varnish it is often desirable to prepare films of uni- 
 form thickness. For this purpose the author has used the de- 
 vice shown in Figure 37.* Briefly, it consists of a horizontal 
 table mounted on a spindle and capable of being rotated at 
 varying speeds. The panel which is to be coated is first gen- 
 erously covered with the varnish and then clamped to the 
 table. The table is then rotated at the desired speed and for 
 the desired time. Under average conditions an ordinary var- 
 nish requires a speed of 300 r. p. m. for 60 seconds to produce 
 a film 25 microns in thickness. For viscous products such as 
 varnish and lacquers, the thickness is practically uniform over 
 the entire film. For plastic products such as paint, the thick- 
 ness decreases with the increase in distance from the center of 
 rotation.* In order to prepare data for use with the spinning 
 table, the following factors involved in the thickness of the 
 film were studied; viscosity, percentage of non-volatile, speed 
 of spinning and time of spinning. 
 
 For this work there were used five varnishes which varied 
 in viscosity and non-volatile content. The determinations of 
 film thickness after spinning these varnishes upon metal pan- 
 els at varying rates of speed for various periods of time are 
 shown in Table 26, column 6. There is also shown in this table, 
 column 7, the calculated film thickness, using the special 
 
 *Sward & Gardner, Ind. & Eng. Chem. Vol. 19 (1927. ) 
 Walker & Thompson, Proc. A. S. T. M. 22 II, 465 (1922. 
 
Film Thickness 7 109 
 
 formula recently developed. A comparison of these esti- 
 mated thicknesses with the actual thicknesses under these 
 varying conditions of speed and time is shown in column 8. 
 
 (CE aa ae er ee ET 
 ge ef SU eran 
 
 a 
 
 Fic. 37 
 
 Spinning Device for Making Films of Uniform Thickness 
 
 TABLE 26 
 
 OBSERVED AND CALCULATED FILM THICKNESS 
 F=0.4N + V! +3 at 290 R. P. M. and 60 Seconds 
 Factors: For 215 RP. M. 1.3 
 
 2 ae ik a 0.8 
 tat ECR. it 
 hk 0.9 
 ‘ i i Non- Speed Time Thicknes . 
 Varnish es Votatil RP. M.| Secs. | Observed Chita Difference 
 ; 215 60 26 30 +4 
 1 1.4 40 290 60 a 23 Moat oo 
 375 Gis rlvioekl o 18 oe 
 Spans 315 60 ey) 31 paeeet 
 290 30 DIS ek ae 26 ed 
 2 0.95 50 290 60 26 24 =% 
 move 1-190 23 22 ete 
 3 755 C60 22 19 3 
 215 60 37 35 = 
 E06 iL 30 33 S0 tia ines 
 3 1.4 50 290 60 29 27 ae 
 290 120 26 24 re 
 pe 615 © 60 25 22 =3 
 Bee TS Sete 60 60 60 0 
 290 30 53 51 Sees 
 4 2.2 50 290 60 43 46 ae) 
 SOO 1a, ea 80 ae 41 +5 
 375 60 39 ay aed 
 a 215 60 44 46 43 
 5 1.4 70 290 60 35 35 0 
 375 60 30 28 =) 
 
 By means of this table, it is possible, within certain limits, 
 to predetermine the time and speed of spinning that will pro- 
 duce a film of desired thickness. 
 
CHAPTER VII 
 DRYING TIME OF FILMS 
 
 There have been disputes among producers and consumers 
 as to the drying time of paints, enamels, oils, and various 
 varnish products. Many of these have been due to the fact 
 that the method of determining the dryness of a film (touch- 
 ing every hour with the finger) has not been well defined, and 
 especially to the fact that observations could not be made with 
 regularity over the drying period which often occurred late 
 at night. 
 
 The fact that drying tests made even under the same condi- 
 tions and on the same materials by different operators are not 
 apt to agree closely, and that the various stages in the drying 
 period are not yet exactly defined, would be indicated by the 
 results of a report of sub-Committee IX on Varnish, of the 
 American Society for Testing Materials. In this work, var- 
 nishes were forwarded to several different operators with the 
 following methods for test: 
 
 ‘Tests are to be made by pouring the varnish on glass and 
 allowing to drain in a vertical position so as to get a flow of 
 approximately 6 in. in length. Before starting the test, the 
 glass plate, as well as the material, should be brought to the 
 temperature at which the test is to be conducted. After the 
 varnish is flowed on, touch lightly with the finger at a point 2 
 in. from the top at 10-min. intervals until it is perceptibly 
 changed from a wet to a sticky condition. Consider this the 
 point of ‘‘initial set.’? Continue touching lightly at 20-min. 
 intervals until the finger can be drawn lightly over the surface 
 without feeling sticky. At this point, the varnish would be 
 considered ‘‘dust-free.’? Continue touching at intervals of 
 one-half hour until a firm pressure of the finger tip does not 
 make a distinct impression. At this point, the varnish would 
 be considered ‘‘dried hard.’’ 
 
 ‘*Reports received from five operators are given in the fol- 
 lowing table:’’ 
 
Drying Time of Films way 
 a aaa a 
 
 TABLE 27 
 
 Gardner Drying Time Meter.—An attempt to overcome some 
 of the factors which have militated against uniform results 
 in drying, the writer a few years ago Hacsioned an automatic 
 drying time meter. This apparatus, which is shown in Fig 38, 
 
 ee eee ee 
 ~ <a = == 
 ne == mes 
 = —_ . 
 
 gee 
 
 = 
 
 ZZ =\NeE 
 yy E\2 
 EB Z =Ne 
 Wy V \ 
 -% j ae 
 GZ 
 
 \ae 
 
 Fic. ~ 
 
 Diagram of drying time meter with section of stand for film. Later models 
 of drum on clock are supported by a lace effect circle of metal rather than 
 with wire. 
 
 consisted of an alarm clock device fastened on an upright 
 support. Attached to the hour hand of the clock is a very 
 hghtly constructed wire wheel covered with a circular drum 
 
 Varnish No. 612 Varnish No. 602 
 
 2 Se Set Dust-Free Hard Set Dust-Free Hard 
 ase 
 ‘d 3 Mini- Maxi- Mini- Maxi Mini- Maxi- Mini- Maxi- Mini- Maxi- Mini- Maxi- 
 z by mum mum mum mum mum mum mum mum mum mum mum mum 
 
 Q, 
 30 75 min. SAO Hrs oa ae a 75 min. 30 hr 
 
 0 oo 60min. 7 ~*~ 13 hr.'21 hr. 23. hr.30 “ 60 min. Dye fe) i hr; 12. “hrs 23 hr 
 remem et. 13° 1116 801g * 30 * 60. * Hee Oia eet Ty ee ay 
 90 40.~ * Bi 63."* see Me RS eS AO ae. Smet V2 2s x 
 30 20 se 30 “cc 54 “cc 12 “<c 12 “ce 2D ce 20 “e 30 “ce 4% “ce % ce 11% “é 22 “e 
 60 30 “e 80 se 544 “é 8 “eé 914 “e 24 “é 30 “e 30 “ce 434 “ee 8144 “é 14 “é 
 90 30m = aS 38% “ om ate Ril eee ne Sio50** The “ _ 
 30 20 “ce 25 “e 5 “ec 61% se 21 ce 23 ce 10 “ec 25 ce 4\ “ce 5% “e 12 “e 23 “<é 
 90 ys hah ies (te Ete ree Ome See VAs ales Res Fuad gah et a Be 
 
112 Drying Time of Films 
 
 esi anna, ORNS 
 formed of light tin plate or of aluminum. ‘The drum is slotted 
 to receive the test piece upon which the coating is applied. 
 This winds under the mandrel rod at the top of the drum and 
 is pressed in contact at that junction with a sheet of soft, light 
 tissue paper of the same width as the test piece. Both of these 
 are automatically pulled from an adjoining double shelf stand, 
 by the action of the clock. Just so long as the coating is wet, 
 it will stain the tissue paper at the point of junction, the paper 
 adhering quite tenaciously to the tacky film. Just at the point 
 of firm setting of the coating, the paper will no longer be 
 stained when it comes in contact with the test piece and will 
 not adhere thereto during its subsequent journey around the 
 drum. 
 
 The test piece developed for this work after a trial of many 
 materials, consists of a roll of celluloid moving picture film 
 (waste short ends of undeveloped raw stock) that has been 
 light struck but not developed. This material was selected 
 because of its opacity (white silver coated surface) upon 
 which, applied, clear coatings are quite evident. Because of 
 its great smoothness of surface, paint and varnish coatings do 
 not penetrate it, but dry upon the surface somewhat as they 
 would upon glass. Moreover, the solvents usually present in 
 paint and varnish apparently do not affect the film, and they 
 seem to evaporate in the same time as they would from tin or 
 glass. Solvents of the ester type, or acetone-containing sol- 
 vents, such as may be used in lacquers, could not be used. 
 Moreover, such film is of a standard size and character of 
 finish and is obtainable in practically any part of the country 
 at a low cost from moving picture firms. 
 
 After the apparatus is set up, it should be standardized by 
 applying a coating of paint or varnish to the film and allowing 
 it to run for a period of twelve hours. The clock is set at the 
 figure 12, at which point the slot for the film will be about 14 
 inch beyond the mandrel rod. The length of film pulled 
 through over that period is then measured and plotted off into 
 twelve sections with sub-divisions if desired. Each section 
 will be substantially 114 inches in length, representing one 
 hour’s time. For an apparatus that has thus been standard- 
 ized, the supply of film to be used therein may then be stamped 
 or printed with such divisions as are desired. 
 
 If the drying time of a product is to be determined, which re- 
 quires a 24-hour drying period, a length of film not exceeding 
 
Drying Time of Films 113 
 a 
 40 inches will generally be found sufficient. It is usual to at- 
 tach the film late in the afternoon and to make the reading for 
 drying time in the morning, the apparatus running auto- 
 matically over night. If the tissue paper at the mandrel rod 
 is still being stained, the test is continued. If no stain is 
 shown, the AR and tissue are both removed and examined to 
 determine point of drying as indicated above. 
 
 In an earlier attempt to construct such an apparatus, one 
 with a series of pegs upon a revolving wire wheel, into which 
 the slotted moving picture film would be drawn, was designed. 
 The pegs were so arranged as to cause an SApSE HE to drop 
 sand upon the drying film every hour. The sand would re- 
 main adherent to the soft, sticky film. When the coating had 
 become dry, the sand would not adhere and would fall off as 
 the film continued its downward journey. A fairly sharp line 
 of demarcation indicating the drying time was obtained. This 
 apparatus, however, aoe ed certain mechanical difficulties that 
 were not overcome. 
 
 Atmospheric conditions such as humidity and temperature 
 will have a profound influence on the drying time of any 
 product. The results obtained one day may not, for instance, 
 be thoroughly in accord with those shown another day. It is 
 the writer’s idea, therefore, that the main application of this 
 apparatus will be for comparative purposes in determining the 
 comparative drying time of two products. This could be done 
 by using two sets of the apparatus (one constructed with a 
 double drum wide enough to accommodate two films would 
 probably cause a slowing down of the clock). Another method 
 would be to use two small films of approximately one-half inch 
 width upon the present size type of drum and apparatus. 
 Tests have, however, been made thus far with two sets of ap- 
 paratus. A varnish or oil having a known drying time is used 
 upon one, and the test coating upon the other. When check 
 tests upon the same coatings applied to glass were run at the 
 same time, the drying time of the latter as determined by 
 touching with the finger, corresponded very closely with the 
 results obtained on the apparatus. 
 
 Sanderson Drying Time Meter. A drying time meter based 
 upon the above apparatus was subsequently worked out by 
 John McE. Sanderson and presented in a paper entitled ‘‘The 
 Mechanical Testing and Recording of the Drying Time of 
 
114 Drying Time of Films 
 
 Paints and Varnishes’”’ before the 1926 convention of the 
 American Society for Testing Materials. The clever device 
 that he has arranged is described below. 
 
 FIGURE 39 
 
 Sanderson Drying-Time Meter showing Sand Dropping from Cones upon 
 Varnished Surfaces. 
 
 ‘‘The design of the mechanism for testing has been simpli- 
 fied as far as possible. Figure 39 shows this machine arranged 
 for comparative testing of two materials although the same 
 design has been carried out with three and four disks, and 
 machines are being tried out with a still greater number. For 
 the variety of materials which it is desirable to test on this 
 mechanism, ranging from quick drying varnishes to slow dry- 
 ing oils, a range of three speeds of the disks appears sufficient. 
 These speeds, one revolution in three hours, once in twelve 
 hours, and once in twenty-four hours, are all obtained from 
 the same clock movement by a change of gears made before 
 the test is started. A fourth speed of one revolution per hour 
 or less has been included in some tests to sharply differentiate 
 quick drying materials. To satisfactorily obtain this speed, 
 however, the use of a separate clock mechanism is required, 
 and for the ordinary run of materials, the three speeds men- 
 tioned above have been found sufficient. 
 
 Si 
 
 I'he drying-time meter as described above, while giving a 
 very satisfactory indication of the time required for a film to 
 dry on the surface, gives no indication of the time required for 
 initial set nor for the film to dry hard. Our recent work has 
 been an effort to adapt the instrument to the testing and re- 
 cording of these other two periods. 
 
  < 
 
 ike - 
 
Drying Time of Films 115 
 
 —— 
 “If a pin point is drawn rapidly across a wet film, the flow- 
 ing out of the mark which it leaves gives a fairly accurate indi- 
 cation of how the material will flow out when brushed, as the 
 pin point acts in a manner quite similar to the individual 
 bristles in a brush.* As long as the mark left by the pin point 
 
 FIGURE 40 
 
 Sand Trails Adhering to Varnishes Tested With Sanderson Apparatus. 
 
 will flow out and disappear, the material can still be brushed 
 without showing permanent brush marks. When the film 
 has set up so that marks from the pin point remain perma- 
 nently, it has also reached the stage where it will no longer flow 
 out when brushed, sprayed, or dipped. 
 
 ‘‘Having determined that this pin scratch method offered 
 a satisfactory means of testing initial set, it was compara- 
 tively simple to devise an attachment for the drying-time 
 meter previously described which would test and record the 
 initial set. The figure shows the drying-time meter complete 
 with this attachment. A shaft mounted horizontially above 
 the outer edge of the coated disks is revolved by a separate 
 mechanism at a speed of one revolution per minute. Carried 
 on this shaft are radial arms terminating in steel points ar- 
 ranged so as to press against the coated disk for a distance 
 of about 11% in. from the outer edge. When this test is carried 
 out with the disks rotating at a speed of once in three hours, 
 the marks made by the steel points are about 0.20 in. apart. 
 When this test has been run to completion, that is, after sev- 
 eral marks in succession show no indication of ean nee ing, 
 the mechanism carrying the points is stopped, the funnels are 
 placed in position, filled with sand, and the testing of the time 
 of surface drying carried out on the same disks. When the 
 
 *A. H. Pfund, “Tests for Hardness, Gloss, Color and Leveling of Varnishes,” 
 Proceedings, Am. Soc. Testing Mats., Vol. 25, Part II, p. 392 “(1925). 
 
116 Drying Time of Films 
 
 material is thoroughly dry, the test is stopped, and the disks 
 brushed off as usual. 
 
 ‘“‘The determination of the time of drying-hard has pre- 
 sented a more difficult problem than the determination of either 
 of the other two transition periods. We have experimented 
 along two different lines, and while neither of our methods 
 has given very satisfactory results, mention of them may be 
 justified as suggestions to other workers on this problem. The 
 first method was to roll a heavy wheel on the film as it dried 
 and attempt to judge the hardness by the impression which 
 it left. The other was to cut the drying film with a razor blade 
 held at an angle and attempt to judge the hardness by a micro- 
 scopic examination of the edge of the cut. The latter method 
 has given results more promising than the former, but has not 
 been worked out to a point where it can be depended upon to 
 indicate comparative hardness between different films. 
 
 ‘“The drying-time meter described is adapted to compara- 
 tive tests only. Results obtained on duplicate tests'on the 
 Same material at the same time check closely. In order to 
 duplicate results at different times and different localities, it 
 will be necessary to regulate and standardize on all the condi- 
 tions such as heat, light, ventilation, ete., which affect drying. 
 It gives a means of study of the effect of various conditions 
 which affect drying which we have not previously had and 
 seems to be the first step toward standardizing drying tests 
 so that we can check a batch of material for drying against 
 an absolute standard of results recorded some time in the 
 past instead of having to make each test against a standard 
 sample.’’ 
 
 A personal communication received from D. V. Gregory 
 of the du Pont Experimental Station comments upon the San- 
 derson type of apparatus which he has found quite satisfac- 
 tory in his work. He had one built which is capable of measur- 
 ing the drying time of 20 products simultaneously and which 
 has an ultimate capacity of 35 products. Gregory states that 
 the end points obtained with this meter do not correspond with 
 any of the points usually measured by the practical varnish 
 man, but he suggests that the results are comparative and 
 have been found very useful. He also states that the so-called 
 ‘“brush-free’’point falls between ‘‘dust-free’’ and ‘‘tack-free,”’ 
 
Drying Time of Films 117 
 
 and that the ‘‘tack-free’’ point is probably a measure of free- 
 dom from ‘‘top tack.”’ 
 
 Drying Time Comparisons. In some determinations of dry- 
 ing time made at this laboratory by the finger test and by 
 Sanderson with his meter, interesting results were obtained. 
 For purposes of test, synthetic resin and ester gum varnishes 
 were prepared. The set-to-touch drying time was taken as 
 that time at which no varnish adhered to the finger when the 
 film was lightly touched. The dust-free drying time was that 
 period when the varnish could be lightly brushed by the finger 
 without showing marring of the film. These tests showed no 
 well defined relationship between the finger test and the San- 
 derson meter test. The long period required for surface dry- 
 ing in the Sanderson test is in striking contrast to the values 
 with the finger dust-free period. The results are given in the 
 table below. 
 
 Camparison of Mechanical and Finger Drying Times 
 
 Set Time —Surface Dry Time— 
 
 Sanderson Sward Sanderson Sward 
 
 Varnish Meter Finger Meter Finger 
 
 1c ee eel Ses: 6 min. 7O min. 30 hrs. 95 min, 
 GR A 25 min. 7O min. 8 hrs. 95 min. 
 ne oO 21 min. 35 min. 21% hrs. 45 min, 
 BeS. ot 16 min. 65 min. 2% hrs. 90 min, 
 E. G. 3 16 min. - 80 min. 13 hrs. 100 min, 
 E. G. 4 14 min. 40 min. SY hrs. 100 min. 
 E. G. 1 20 min. 90 min. 71% hrs. 100 min, 
 
 It would appear that the differences shown might be due to 
 films of unequal thickness as obtained by the two operators. 
 
 Effect of Driers upon Viscosity and Color of Varnish. In 
 the determining the drying time of a series of varnishes made 
 with B.S. synthetic resin and with ester gum, and which con- 
 tained varying percentages of different types of driers, some 
 interesting results were secured. These results were fully 
 reported in Scientific Section Circular No. 301. A table of the 
 results, indicating the change of viscosity effected by the 
 drier, is presented below. 
 
118 Drying Time of Films 
 
 en reer eee —————————— 
 
 TABLE 28 
 Flowed on glass* 
 sek - “eyes 
 Actual to dust- 
 non- touch free Color 
 Drier volatile Viscosity min- min- G-H 
 Varnish Percent Metal Percent G-H Potses utes utes Scale 
 ice 0.2 5 48.1 D-E 1.15 70 95 if 
 A nee feak Se 0.02 ea 50.7 F 1.40 70 95 5 
 35. pelts 0.002 Co 50.8 EF 1355 70 100 5 
 7) 2 ee Cae 0.5 Pb 50.6 G 1.65 70 95 5 
 S-Bo.os Re 0.2 Pio 49.8 G 1.65 90 100 5 
 soe ew beet ao 0.2 Mn 555 G-H 1.85 90 100 7 
 0.005 Co 
 EU Face ay a 0.05 Mn 50.8 G 1.65 75 90 6 
 0.2 Pb 
 0.005 Co 
 $-B..5. RR. 0.005 Mn 50.3 E 1:25 70 95 5 
 0.02 Pb 
 9-B- SR, 0.2 Mn ee F-G 1.55 35 45 7 
 0.5 Pb 
 10-B. S. R. 0.08 Mn 51.3 G 1.65 70 05 EG 
 0.2 Pb 
 0.005 Co 
 11-BaS 0.05 Mn 50.9 G 1.65 65 90 6 
 0.5 Pb 
 12-Booo kk None 49.1 F 1.40 70 95 5 
 1-E. G. 0.2 Co 49.5 C22 0.95 80 100 8 
 2-E A. 0.02 Co 49.5 F 1.40 75 95 6 
 Sali G, 0.002 Co 48.7 F 1.40 80 100 6 
 4-H A, 0.5 Pb 50.4 F 1.40 40 100 6 
 SB: 0.2 Pb 50.1 F 1.40 100 120 6 
 6-E. G. 0.2 Mn 51.6 G 1.65 80 100 8 
 0.005 Co 
 f oS Ones Os 0.05 Mn 53-3 G 1.65 85 100 7s 
 0.02 Pb 
 0.005 Co 
 8-E 0.005 Mn 49.6 F 1.40 85 100 6 
 0.02 Pb 
 9.fG. 0.2 Mn Siz F-G 135 90 100 9 
 0.5 Pb 
 10-E. G. 0.08 Mn nN) G 1.65 90 100 8 
 0.2 Pb 
 0.005 Co 
 11-EG. 0.05 Mn 53.4 F 1.40 90 100 7 
 0.5 Pb 
 12-EoG: None 49.4 D-E its 95 100 6 
 
 Driers in Varnish Affect Physical Properties.—Some results 
 of a study of various driers in a large number of varnishes 
 
 gave the following indications: 
 
 * Many of these varnishes, when brushed on a surface would set to touch in 15 
 to 30 minutes. With “flowed” films, the thickness is very much greater, and a 
 
 much longer period is necessary. 
 
Drying Time of Films 119 
 
 1. The kind and concentration of drier has an influence on 
 the properties of a varnish. 
 
 2. It is even possible to prepare some types of varnishes 
 without driers. They will set and surface dry in about the 
 Same time as similar varnishes containing driers, but may 
 attain their final hardness more slowly. Varnishes free from 
 drier might be suggested for exterior purposes, but it is ques- 
 tionable whether this would apply for such varnishes as may 
 be used upon floors where hard drying is required. 
 
 3. Large amounts of any kind of drier do not accelerate the 
 drying of a varnish to any marked extent. On the other hand, 
 large amounts of driers may reduce the resistance of the film 
 to saponification by alkali, and tend to make the films more 
 brittle. | 
 
 4. Lead or cobalt driers reduce the elasticity of varnish films 
 less than manganese driers. The two former types are there- 
 fore indicated for spar varnishes which must meet elasticity 
 requirements. 
 
 9. Neither lead nor cobalt driers produce skinning of stored 
 varnish as rapidly as manganese driers. 
 
 Ozone Apparatus for Drying Insulating Varnishes.—Ozone 
 has been used to advantage in the drying of insulating var- 
 nishes by Spence and Cochrane.* The apparatus used by them 
 is shown in Fig. 41. Tests made to determine the insulating 
 properties and absorption of moisture of films when air baked 
 are given in a table in that paper. A summary of their work 
 would indicate the following: A process has been developed 
 for using ozonized air in the baking of typical insulating var- 
 nishes. A saving of 50 per cent of the time usually necessary 
 in the air baking process has been demonstrated. The films 
 thus produced are of equally good electrical properties as air 
 baked films and the water resistance of the films equal to that 
 of air baked films. The acidity of the films is not increased 
 by the ozone treatment. The films baked just to dryness in 
 ozone are equal in heat resistance to air baked varnishes. 
 
 Testing the Drying Time of Coatings under Colored Light. 
 In some experiments made by the writer, eight open top boxes 
 
 *“The Utilization of Ozone in the Drying of Insulating Varnishes,” by 
 EK. B. Spencer and L. U. Cochrane. Scien. Sec. Cire. No. 290. 
 
120 Drying Time of Films 
 
 ———— 
 of rather porous cardboard were constructed, approximately 
 six inches square and about one inch deep. The boxes were 
 inverted, so that when placed on the table a small dark cabinet 
 was made. In placing these boxes on the table, they were 
 raised sufficiently to allow the free passage of air. In all but 
 
 FIGURE 41 
 
 Apparatus for the production and analysis of ozonized air. 
 
 one of these boxes, which was left for a dark cabinet, a hole 
 four inches square was cut in the top. In one of these the 
 hole was left without a cover glass, but in the remainder a 
 cover glass was used. These cover glasses were of transpar- 
 ent glass in red, green, blue and yellow, while two were of 
 colorless glass, one plain and the other opaque ground glass. 
 The hight was passed through these glasses onto a thin film of 
 
 raw linseed oil spread over a glass slide about four inches 
 square. 
 
 iS ee 
 
Drying Time of Films 121 
 
 snes 
 
 The boxes were placed in the window exposed on the south- 
 ern side, where they received direct sunlight. All exposures 
 were within the laboratory, which was maintained at a tem- 
 perature of about 70° F. 
 
 Box 
 Box 
 Box 
 Box 
 Box 
 Box 
 Box 
 Box 
 
 SOUTHERN EXPOSURE (Direct Sunlight) 
 Raw Linseed Oil. 
 
 RSE The SUE a ST a Eh a) Wet as when put in after 4 days 
 Matienole but without class. ...........'. Dry in 2 days 
 BViCNe ial -lASS COVES... 5. ce ee cc Dry in 2 days 
 Merten Class COVEY... ... sos chee one Dry in 2 days 
 CU IASS COVER. oo uc s cc lace oe ee os Dry in 3 days 
 Syitieomiper S1ASs COVEr... 6... ce ee Dry in 2 days 
 MaitineniMere lass “COVE? .. eis. ee oe ek ee Dry in 8 days 
 Mitiieereen Class COvVer.,.......2..6600. Dry in 3 days 
 
 Experiments discontinued after 4 days. 
 
 The word “dry” refers to condition of dryness to touch but not fully hard. 
 
 This subject has been briefly treated in Scientific Section 
 Circular No. 172 in which there is an abstract of work that 
 has been done in various places. 
 
CHAPTER VIII 
 TEMPERATURE AND HUMIDITY CONTROL CABINETS 
 
 In the preceding chapter, the difficulties of obtaining uni- 
 form drying time results in various laboratories are discussed. 
 Similarly, check results cannot be obtained in determining the 
 tensile strength and elongation of paint and varnish films un- 
 less the test specimens are first aged in a cabinet having the 
 desired humidity. As indicating the importance of building in 
 a paint laboratory a constant humidity room, there are given 
 below the results on the hardness of four different varnishes, 
 as determined by the Pfund hardness tester, under three dif- 
 ferent conditions of temperature and humidity. Tests made 
 in an ordinary room on one day cannot be compared with tests 
 made a few months later under different temperature and 
 humidity conditions. With standard temperature and humid- 
 ity, however, comparable results may be obtained. The tests 
 referred to below were made by Gregory on films which had 
 dried for one week at 77° F. and 50% relative humidity. 
 
 Wis as 3 98° F. 98° F. 
 
 50% R.H. 50% R. H. 25% Bo. 
 G gal, rosin-wood oll. varnish:s ose ee 1300 170 950 
 6 “ ester gum-wood oil varnish......... 13800 270 850 
 6 “ zine resinate-wood oil varnish...... 2600 1750 1840 
 6 “ limed rosin-wood oil varnish....... 1450 1150 1350 
 
 The above figures represent the number of grams necessary 
 to produce a definite circle of contact between the ball bearing 
 and the varnish surface. 
 
 From time to time laboratories have devised small cabinets 
 arranged with heating and humidifying devices. Some of the 
 work that has been done in this connection is outlined below. 
 Special attention should be drawn to the latter section which 
 deals with the Walker type of humidity room. Correspond- 
 ence with the Research Division of The New Jersey Zine Co. 
 at Palmerton, Pa., elicited information regarding a small cabi- 
 net which they have constructed and which is shown in Fig. 42. 
 A description of this cabinet is given below. 
 
 _ Palmerton Cabinet.—‘‘We have gotten along, after a fash- 
 lon, by using small cabinets which are maintained at room 
 temperature or slightly above, for which the constant humid- 
 ity has been provided by passing air through sulphurie acid 
 
120 
 
 Temperature and Humidity Control 
 
 ‘SoTO}BIOGVT “OD ouIZ “f ‘N sq pasg JouTqro 
 CF AVON 
 Ulf HYE{O/ Of 1OJOY/ 
 
 SAGUIEYD UNE 
 Of JOGUILY: 
 "bunlajem 
 wod, bur 
 
 peal Sf10q 
 
 *0OS 7H ANI 
 WeUO) sHyog 
 
 An aul7 
 AY sfaaye” Ol 
 payeulebyet 
 
 SOWA {Uf 
 
 a 
 SOIWIAXT JOWMAAY 
 
 ma, do, May {U01/ 
 fauige) Ajiplunp/ pue ainpesadulay {Ue{SUOD fauige7 Kyipiuinyy pue ainjesadilal JUe{SUOF 
 
124 Temperature and Humidity Control 
 
 of a definite specific gravity. Tables showing the specific 
 eravity of sulphuric acid necessary to maintain any specified 
 humidity at a certain temperature, have been published by 
 Wilson and will be found in the Journal of Industrial and 
 Engineering Chemistry, Volume 13, No. 4. In applying this, 
 we use the ordinary laboratory air supply and pass the air 
 through a series of at least three liter bottles; the first one of 
 which (that is, the one nearest the air line) is changed at least 
 every twenty four hours, and the other two moved up, while 
 the third, or last, bottle is replaced by one containing sulphuric 
 acid of exactly ays required concentration. This scheme, of 
 course, has its disadvantages as it is necessary to test the vate 
 tion daily and the volume of air that can be passed through is 
 rather limited. However, we find that it works very well 
 within the limits of its capacity.” | 
 
 Correspondence with F. P. Veitch, Chemist in Charge of 
 Naval Stores Investigations, of the Bureau of Chemistry, U. 
 S. Department of Agriculture, referred to the constant tem- 
 perature and humidity room which is used at the Bureau of 
 Chemistry. It apparently contains rather expensive equip- 
 ment. The reference is as follows: 
 
 Bureau of Chemistry Cabinet.—‘‘This room is described in 
 an article entitled ‘A Constant Temperature and Humidity 
 Room for the Testing of Paper, Textiles, ete.,’ which was pub- 
 lished in the January, 1918, issue of the Journal of Industrial 
 and Engineering Chemistry, page 38. 
 
 “The hygrostat control used in our room is manufactured 
 by the Carrier Engineering Corporation, Land Title Building, 
 Philadelphia, and is catalogued as Type F. The thermostat 
 shown in the illustration is manufactured by The Powers Regu- 
 lator Co., 101 Park Avenue, New York, N. Y. We have 
 recently replaced this thermostat with the Tycos Type-P tem- 
 perature regulator (reverse action), manufactured by the Tay- 
 lor Instrument Companies, Rochester, N. Y. This is the only 
 change we have made in our room since the publication of its 
 description.’’ 
 
 Correspondence with the Bureau of Standards in regard to 
 the drying cabinet in the Ceramic Division, the humidity room 
 in the Textile Division, and the air conditioning equipment 
 in the Paper Testing Section, is abstracted below. 
 
 a 
 
Temperature and Humidity Control B25 
 
 FIGuRE 43 
 Electrically Controlled Moist Cabinet With Recording Gauges for 
 Drying Painted Panels. (Gardner Laboratory.) 
 
 FIGURE 44 
 
 Ventilated Moist Cabinet for Studying Drying Time of Oils and Varnishes. 
 (Gardner Laboratory. ) 
 
126 Temperature and Humidity Control 
 
 Textile Division Cabinet.—‘‘ A description of a Carrier Dry- 
 ing Cabinet used by our Ceramic Division was published in 
 the November, 1925, issue of the Journal of the American Cer- 
 amic Society, page 691. This cabinet is one of various types 
 and sizes manufactured by the Carrier Engineering Corpora- 
 tion. The following equipment is used in the textile section. 
 
 ‘‘ Mir conditioning Equipment: : 
 
 ‘Ammonia compressor, 714 tons capacity; Automatic Re- 
 frigerating Company, Hartford, Conn. 
 
 ‘Carrier Humidifying System; Carrier Engineering Com- 
 pany, 1402 Land Title Building, Philadelphia, Pa. 
 
 ‘‘Tyeos Wet and-Dry Bulb Thermometer Recorder; Taylor 
 Instrument Company, Rochester, N. Y. 
 
 ‘Hor very accurate determination of humidity, Fuess As- 
 perator, Kreuger and Toll Corporation, Engineering Building, 
 114-118 Liberty Street, New York City. The Comins Electro- 
 Psychrometer, American Moistening Company, 52 Chancey 
 Street, Boston, Mass., is considered equally suitable. 
 
 ‘‘Size of Room, 45 x 30 x 12 feet. 
 
 ‘¢ Automatic Control— Ammonia refrigeration is used during 
 warm weather and steam during cold weather to obtain the 
 desired temperature. The atmospheric conditions are auto- 
 matically controlled within + 3 per cent of 65 per cent relative 
 humidity and within + 3° F, of 70° EF. temperature. ”’ 
 
 Air Conditioning Equipment of Paper Section. ‘‘An air 
 conditioning and testing cabinet is being developed by the 
 Paper Section for use in making tests of physical properties 
 of paper. The air is conditioned by drawing it through a sul- 
 phurie acid solution of the correct concentration to give the 
 desired humidity in the cabinet. The testing instrument is 
 placed inside the cabinet and by means of rubber gloves pro- 
 vided with flexible sleeves, the test specimens are manipulated 
 from outside the cabinet, thus obviating the necessity of open- 
 ing it. No means have been provided for controlling tempera- 
 ture as this has been found unnecessary in testing paper. 
 
 Correspondence with the Forest Products Laboratory, U. S. 
 Department of Agriculture, at Madison, Wis., resulted in the 
 receipt of a very interesting report entitled ‘‘ Automatie Regu- 
 lation of Humidity in Factories,’’ by A. C. Knauss, Engineer 
 in Forest Products. This report which is bound and which 
 contains 16 pages and several illustrations, will probably be 
 of considerable interest to those contemplating the use of 
 ‘humidity in factory control work. One of the illustrations in 
 the article is reproduced below, by permission, as Fig. 45. 
 
 Sg ee a ees 
 
127 
 
 Temperature and Humidity Control 
 
 ’ 
 
 3 
 
 SHIWOWSIY {Ul0y Ke NG 
 
 \ si aes 
 
 | t @}: 
 BAlOA Buixtp/ 
 
 CYA VoSsipOW/ 
 hs0jOs0go7 ‘Ynposy {63/04 @) AbBazw 
 
 cniosoddy josuoy hiypiwnyy 
 
 0 fuawabuossy 
 
 LING JS 
 
 bur JOOIAMALO/Y: ote 
 ug 
 
 wzzon hosde 
 
 ? 
 
 resulted in information regarding a type of 
 000. . 
 
 ) 
 
 Figure 45 
 
 ? 
 
 Correspondence with the Materials Section, U.S. Navy Yard 
 
 Brooklyn, N. Y. 
 
 apparatus constructed during 1919 at a price of about $4 
 
 A description of the apparatus is given below. 
 
128 Temperature and Humidity Control 
 
 Navy Yard Cabinet. ‘‘The room in which the conditioned 
 air is discharged from the apparatus is about 8 ft. x 11 ft. and 
 9 ft. high. It is completely insulated on all sides, roof and 
 floor with 2 in. of compressed cork covered on ceiling and walls 
 with 1% in. of Portland cement. 
 
 ‘The air in the above room is maintained at a temperature 
 of 70° F. + 1° and at a relative humidity of 65% + 2% by the 
 following processes. 
 
 ‘¢ Air is taken from outside of the above room at any tem- 
 perature and humidity within the capacity of the apparatus 
 and drawn by a suction fan into a large sheet metal spray 
 chamber. 
 
 “The air is drawn through a curtain of whirling water 
 which is maintained at a low temperature by flowing over a 
 bank of Bandulot ammonia coils forming part of a two ton ice 
 machine. 
 
 ““The water is recooled through recirculation over the coils 
 by means of a motor driven centrifugal pump. 
 
 “The air passing through the water in the spray chamber 
 is cleansed and reduced in temperature to that of the cooling 
 water at which temperature the air is 100 per cent saturated 
 and is mixed with entrained moisture. 
 
 ‘The air then passes over a Vento steam coil to which steam 
 is admitted through thermostatic control and then passes 
 through a chamber containing moisture eliminators which re- 
 move all the entrained water present other than in vapor form. 
 
 ‘After leaving the moisture eliminators the air passes over 
 the stem of a thermostat which is so set as to admit and cut 
 off steam to and from the above Vento heating coil which heats 
 the air to a constant temperature at the thermostat of 57° F. 
 at which temperature the air contains 100 per cent humidity or 
 .7464 lbs. of moisture per 1000 cu. ft, of mixture of air and 
 moisture. 
 
 ‘The air then passes over a second set of Vento heating 
 coils which further raises the temperature and thus reduces 
 the relative humidity. It does not matter how high it is heated 
 provided that after passing the heater, it reaches the room 
 at the required temperature of 70° F. A thermostat in the 
 room controls the steam admission to the second set of heating 
 coils and is set at such a point that the air always is reduced to 
 the desired constant room temperature from that which it has 
 after passing over the heating coil. 
 
 ‘‘The humidity as stated above drops after passing over 
 the second set of coils from 100 per cent saturation to a per- 
 centage corresponding to the dry temperature of the air after 
 it passes over the second heater. As the air cools after passing 
 
Temperature and Humidity Control 129 
 
 over the second heater the relative humidity increases to that 
 corresponding to a dry temperature of 70° FE. This will be 
 65 per cent relative humidity if the absolute humidity of the 
 air as it passes over the thermostat in the eliminator chamber 
 is .7464 lbs. per 1000/cu. ft. at 56-57° F. saturation. 
 
 ‘To summarize the atmospheric conditions in relation to 
 that existing outside the conditioning room and that inside 
 the room: 
 
 ‘“(a) Inside the room, a constant temperature of 70° F. and 
 a constant relative humidity of 65 per cent requires a constant 
 absolute humidity of .7464 Ibs. per 1000/cu. ft. of mixture of 
 moisture and air. 
 
 ‘“(b) To produce air containing .7464 lbs. per 1000/eu. ft. 
 requires that the outside air shall be passed through a water 
 spray the temperature of which is 57° F. At this temperature 
 the air assumes a relative humidity of 100 per cent and con- 
 tains .7464 lbs. per 1000 cu. ft. of moisture. 
 
 ‘“(c) By heating the saturated air (100 per cent humidity— 
 o/° F. dry, wet and dew point temperatures) so that it has a 
 dry temperature of 70° F., dry bulb, the relative humidity 
 drops from 100 per cent to 65 per cent, and the wet bulb then 
 rises from 57° to 62° F. the absolute humidity remaining the 
 same as before—.7464 lbs. per 1000 cu. ft. 
 
 ‘‘From the above it is readily seen how air at any tempera- 
 ture and humidity (within the limits of the apparatus) can 
 be transformed into air having a constant dry temperature of 
 70° F. and a constant relative humidity of 65 per cent. 
 
 ‘The air conditioning room in the Laboratory Section is 
 capable of performing the following: 
 
 ‘‘(a) Washes and cleanses the air delivered to the testing 
 room during all seasons of the year. 
 
 ‘“‘(b) Cools the testing room in summer to a temperature 
 of 70° or less in weather of not exceeding 95° F. dry bulb or 
 78° F. wet bulb temperature. 
 
 ‘“(c) Heats the room to a temperature of 70° F. or more in 
 weather of 0° F. or less. 
 
 ‘“(d) Maintains not less than 65 per cent humidity in the 
 room during all seasons of the year without regard to the 
 outside weather conditions within the above limits. 
 
 ‘“‘(e) Automatically controls the dampers and valves con- 
 nected with the room control between full-open and full-closed 
 with a variation in relative humidity of 4 per cent or less. 
 
 ‘“(f) Automatically controls the dampers and valves con- 
 nected with the room temperature control between full-open 
 and full-closed with a variation in temperature of 2° or less. 
 
130 Temperature and Humidity Control 
 
 ‘“(@) Provides copious and continuous ventilation to the 
 room during all seasons of the year. 
 
 ‘‘Permanent records are maintained of the atmospheric con- 
 dition in the room by means of a recording wet and dry bulb 
 thermometer from which the relative humidity is readily 
 determined.’’ 
 
 Walker Apparatus—tThe type of humidity room devised 
 by Walker, Steele and Hickson of the Bureau of Standards 
 and originally described by them in Scientific Section Cireular 
 No. 310 is given below. The apparatus shown was built in the 
 paint and varnish testing laboratory of the Bureau of Stand- 
 ards for maintaining accurate control of temperature and hu- 
 midity where paint films are tested. The room which is of ex- 
 tremely simple construction is kept at constant humidity by 
 blowing air over a saturated solution of magnesium chloride. 
 The temperature is also maintained within close limits by a 
 simple device. It is understood that this room, which is large 
 enough for several testing instruments and which will accom- 
 modate one or two operators, was constructed at a cost of 
 about $600.00. Their description follows: 
 
 ‘While definite conditions of humidity and temperature are 
 at least desirable if not necessary in testing the time of dry- 
 ing of paint, varnish, ete., and in making physical tests on films 
 of such materials, there is no reason other than convenience 
 for deciding just what these definite conditions should be. At 
 30° C. (86° F.) and 32 per cent saturation an operator experi- 
 ences no serious discomfort and since there are very few days 
 in the year when the indoor temperature is any higher than 
 30° C. this temperature can be maintained in most places with- 
 out using refrigeration. Saturation of 32 per cent is easily 
 and cheaply maintained by using a saturated solution of 
 MegCl.6H.O. It is therefore suggested that where standard 
 conditions are necessary or desirable 30° + 2° C. and 352 
 + 4 per cent saturation be used as standard conditions of 
 temperature and humidity in all testing and research work 
 on paint, varnish, and similar materials.’’ 
 
 International Critical Tables, Vol. 1, pp. 67-68, give informa- 
 tion as to the percentage saturation of air in contact with 
 saturated solutions of a large number of salts. This percent- 
 age saturation for many salts varies only slightly with changes 
 in temperature. For example, the above authority gives the 
 following extreme ranges of per cent, saturation CaCl.2H.O 
 90° to 160° C. 16 to 18 per cent, CaCl.6H20 10° to 24.5° C. 38 
 to 31 per cent, MgCl6H2O 10° to 50° C. 35 to 31 per cent, 
 
Lemperature and Humidity Control 131 
 
 Mg (NOs)2 6H20 18.5° to 24.5° C. 52 to 56 per cent, NaCl 0° to 
 110° C. 78 to 73 per cent. 
 
 _In looking over these figures it seemed to the writers that 
 it would be a very simple matter to maintain a constant per- 
 centage saturation by passing a stream of air through a wash 
 bottle containing a suitable saturated solution with some of 
 the undissolved crystals and then passing the air into any con- 
 venient vessel, for example, a bell jar. Experiments with this 
 
 Figure 46 
 
 View of Constant Temperature and Humidity Room Constructed in Paint 
 and Varnish Section of Bureau of Standards at Cost of Approximately $600. 
 
 type of set-up gave percentage saturations in the bell jar 
 that varied widely and were not what would be expected from 
 the data given in International Critical Tables. The reason 
 for this failure is not hard to understand when one considers 
 
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Temperature and Humidity Control 133 
 
 the large difference in the amount of water vapor in saturated 
 air at different temperatures and the latent heat of water and 
 the heat of solution of various salts. The weight in grams of 
 the aqueous vapor in a cubic meter of saturated air varies 
 fotebeit esate lo. ©. to 39.187 at 35° C. If air is given a 
 definite relative humidity at say 17° C. and then raised in 
 temperature to 18° the relative humidity will be about 94 per 
 cent of what it was at 17° C.; and if it is cooled to 16° C. its 
 relative humidity will be about 106 per cent of what it was 
 Grakc ©. | 
 
 If air is passed into a solution having a vapor pressure 
 greater than the partial pressure of the water vapor in the 
 air, water is taken up by the air and the solution is cooled 
 by evaporation. If the vapor pressure of the solution is less 
 than that of the air introduced, water is condensed and its 
 latent heat raises the temperature of the solution. The heat 
 of solution of the salt which dissolves or is precipitated in the 
 two cases respectively is also a factor. 
 
 It follows from the above that it is very much simpler to 
 maintain a given lot of air in a confined space at a fixed rela- 
 tive humidity by means of saturated salt solutions than it is to 
 condition a continuous stream of air flowing from outdoors 
 or the room into a chamber. 
 
 It is important to have the walls of a humidity chamber 
 made of non-absorbent material, and if a fixed temperature is 
 to be maintained they should be well insulated. 
 
 Experiments with a metal lined box 75 em. deep, 75 cm. 
 long, and 40 em. wide provided with a tight top show that it 
 ean be easily maintained at almost any desired humidity by 
 directing the air from a very small (5 em.) electric fan (2500 
 r. p.m.) placed in the bottom of the box across the surface 
 of a saturated solution of a suitable salt in a photographic 
 tray or crystallizing dish. With the fan and motor in the box 
 the temperature is a few degrees above that of the room, but 
 since the solution has the temperature of the air in the box the 
 relative humidity remains constant. When low humidity only 
 is required, this simple set-up is entirely satisfactory and can 
 be run continuously. With very high humidity the motor 
 might be ruined and under such conditions it is best to put the 
 motor outside the box with the shaft passing through to the 
 fan on the inside. 
 
134 Temperature and Humidity Control 
 
 With this apparatus the specified humidity ean be attained 
 in about 30 minutes and maintained thereafter. The follow-. 
 ing humidities were shown by a recording hair hygrometer 
 calibrated by wet and dry bulb for the humidity range covered. 
 No deviation from the average greater than one per cent was 
 recorded during 24 hours. 
 
 TABLE 29 
 
 Humidities Observed With Box Apparatus Using Several Salt Solutions 
 Humidity Time after closing Humidity in 
 
 in room box to reach de- box 
 Humidifying agent per cent sired saturation per cent 
 Saturated soln. MgCl6H.O......:.... 30 30 min. 32 
 pacturated soln, (atLen 0 ous 39 380 min. 30 
 Saturated soln. Mg(NO,).6H,O...... ot 15 min. 53 
 saturated ‘soln... Ne@h 06. 65 wee 41 45 min. 77 
 Wels oun eaietooo ee ee ee eee Ps) 30 min. 100 
 
 A glass cabinet of about the same dimensions as the box 
 described above but having a sliding door on one side (very 
 similar to a large balance case) has been found convenient 
 where exposure to hght under definite humidity conditions is 
 desired. With such a cabinet it is advisable to connect a re- 
 sistance in series with the motor so as to run the fan at a low 
 speed. <A strong current forces considerable air through the 
 openings around the sliding door resulting in too much inter- 
 change between the air of the room and the cabinet, and the 
 heat from the motor raises the temperature more when the 
 fan is running at full speed, so that on opening the door there 
 is a greater fluctuation of humidity than when the fan is run- 
 ning at say 800 r. p.m. With the fan running at full speed, 
 room humidity 36 per cent and Mg(NOs)26H.O in the cabinet 
 the humidity in 30 minutes rose to 50 per cent and remained 
 there for 90 minutes. On allowing the door to remain open 
 for about one minute, the humidity dropped to 47 per cent and 
 in 15 minutes after closing it had gone up to 51 per cent, re- 
 mained at 51 per cent for 214 hours then gradually rose during 
 the next 90 minutes to 54 per cent and remained between 53 
 per cent and 55 per cent from 4.00 p. m. to 9.00 a. m. 
 
 Figure 47 gives the design and specifications for a metal- 
 lined insulated cabinet large enough for a man to work in, 
 which is in use at the Bureau of Standards. This room is 
 maintained at 30° C. so that it can be used practically the year 
 round without artificial cooling. The relative humidity is 
 kept at about 32 per cent. The temperature is controlled by a 
 small electric heating coil regulated by a thermostat. <A 20 
 
Temperature and Humidity Control ri5 
 
 x 20 inch photographie tray containing about 10 pounds of 
 MgCl.6H.O and enough water to dissolve about half of the 
 salt is placed on the floor and the draft from an ordinary 
 electric fan played across the surface of the liquid. With 
 the precaution of opening only one door at a time on entering 
 or leaving the room the humidity can be maintained at 32 per 
 cent saturation and the temperature at 30° C. within the limits 
 shown below. 
 
 A sample record taken on February 2, 1927, from 10.00 a. m. 
 to 4.00 p. m. with fan and heater in operation showed a rela- 
 tive humidity of 32 + 0.5 per cent, and a temperature between 
 30° and 30.5° C. During part of this time one man was in the 
 eabinet. At 4.30 p. m. the fan and heater were shut off; the 
 humidity recorder remained constant at 32 + 0.5 per cent until 
 9.30 a. m. on February 38. The temperature was not taken 
 after 4.00 p.m. on February 2. 
 
 Another record was made on February 14 and 15, 1927. 
 The temperature remained between 30° and 30.5° C. from 12 m. 
 to 4.30 p. m. A man entered the room several times during 
 this period and remained in it for about 214 hours. At 4.30 
 p. m. the fan and heating coil were shut off. At 9.30 a. m. on 
 February 15, 1927, the temperature was 22° C. The humidity 
 remained constant at 31+ 1 per cent for the entire time (12:00 
 m. on February 14 to 9.30 a.m. on February 15). The humid- 
 ity and temperature in the room in which the cabinet is located 
 varied between 34 per cent at 23.3° C. and 40 per cent at 18.9° 
 . 
 
 It is advisable to stir the mixture of MgCl.6H.O crystals 
 and solution at least once every day. 
 
 This insulated cabinet has not been operated in warm humid 
 weather, and it may be found convenient under such condi- 
 tions on starting the operation to first reduce the humidity to 
 about 32 per cent by blowing the air over dry CaCl, and then 
 remove the CaCl. and replace the MgCl.6H.O mixture. 
 
CHAPTER IX 
 SPECIFIC GRAVITY DETERMINATIONS 
 
 A method worked out in this laboratory for the determina- 
 tion of the specific gravity of paint pigments was later adopted 
 with some modifications by the American Society for Testing 
 Materials. This original method which appeared in an early 
 edition of this volume is now replaced by the standard methods 
 of test which are given below. 
 
 A. S. T. M. STANDARD METHOD OF TEST FOR SPECIFIC 
 GRAVITY OF PIGMENTS 
 Issued As Tentative, 1923; Adopted, 1924. Revised 1927. Method A: For 
 Routine Testing of Several Samples Simultaneously, | 
 I APPARATUS 
 
 1. The apparatus shall consist of the following: 
 
 (a) A pyknometer as shown in Fig. 48 (a) or (0), having a capacity of 
 50 ce. 
 
 (b) A water bath consisting of a vessel filled with sufficient water to per- 
 mit of only a very gradual rise in temperature and equipped with a stirring 
 device, preferably air blown. 
 
 (c) An open tube manometer, made of glass tubing 6 mm. in diameter, 
 filled with mercury to approximately 86 em., fitted with pressure tubing 
 attached to a Y tube leading to the desiccator and the pump. 
 
 Nore.—The difference in levels of the mercury in the manometer when the 
 System is in operation, subtracted from the barometer reading taken at the 
 same time, gives the vacuum of the system in millimeters of mercury. The 
 Se between the barometer and the manometer reading should not exceed 
 
 mm. 
 
 (d@) A glass desiccator, having a hole at the side, constructed with heavy 
 walls to withstand a vacuum of one atmosphere. 
 
 (e) A laboratory water vacuum pump to expel the greater portion of air 
 in the desiccator. 
 (f) An oil. vacuum pump with motor to give a vacuum of not more than 
 3 mm. 
 
 Nore.—The Hyvac oil pump is satisfactory. This pump has a displacement 
 of approximately 200 cu. in. per minute or 7 cu. ft. per hour at a speed of 900 
 
 r.p.m. It will evacuate a flask of one-liter capacity to a vacuum of 1 mm. 
 in two minutes. 
 
 (9g) A weighing bottle with cork. The neck shall be small enough to fit 
 inside the neck of the pykometer. This latter requirement is essential, since 
 small quantities of pigment easily adhere to the ground-glass joint of the 
 pykometer. 
 
 (j) A thermometer having a range of from 0 to 60° C. graduated in 0.1° C. 
 
 II. PROCEDURE 
 2. The pykometer shall be filled with freshly boiled distilled water and 
 brought to-a temperature of 15.5° C. It shall be dried and weighed as specified 
 in Section 7. It shall then be cleaned, weighed, and dried. It shall then be 
 
 [ia 
 
Specific Gravity Determinations 137 
 
 filled with the kerosene to be used in making the test and again brought to a 
 temperature of 15.5° C., and dried and weighed in the same manner as before. 
 The specific gravity of the kerosene shall be calculated from the formula. 
 /15.5° C. _ Weight of Kerosene 
 
 Weight of Water 
 3. The pigment shall be dried in an oven at 105° C. for 2 hours. 
 Nore.—It is preferable to use an electric oven for this purpose. 
 
 Specific Gravity 15.5 
 
 Thermometer. 
 
 Thin, long 
 Capillary 
 Tube 
 
 Capillary 
 Tube-->! 
 
 (a) (b) 
 FIGURE 48 
 
 4. A sample of the pigment shall be weighed, by difference, in the weighing 
 bottle. For blacks, blues, and lakes of light specific gravity, about 1 g. should 
 be used ; for inert crystallin pigments, about 4 g.; for opaque white pigments, 
 7 to 10 g.; and for red lead, from 15 to 20 g. should be used. 
 
 Norre.—Due to the hygroscopic nature of some of the pigments it is neces- 
 Sary to use a weighing bottle fitted with a cork stopper. 
 
 5. Sufficient kerosene shall be poured into the pyknometer to form a 14-in. 
 layer in the bottom and a quantity of pigment from the weighing bottle shall 
 be added reaching approximately three-fourths of the distance to the kero- 
 sene level. The kerosene shall always cover the pigment. The sample shall 
 be stirred with a polished round-bottom glass rod until completely covered 
 by the kerosene, more kerosene being added from the wash bottle if neces- 
 sary. The rod shall be washed with kerosene. 
 
 6. The pyknometers shall be placed in the desiccator, which shall then be 
 closed and attached to the water pump until the greater part of the air is 
 expelled from the system. This takes from 5 to 10 minutes. The system 
 shall then be closed with a pinchcock and the desiccator attached to the oil 
 pump for the removal of the small amounts of air given off at the low pres- 
 sures obtainable with the oil pump. The manometer is used to indicate 
 whether the oil pump is giving the proper vacuum. When the manometer 
 indicates that the vacuum, which should not be greater than 3 mm., is con- 
 stant, the oil pump may be cut off for short periods, precaution being taken 
 that the vacuum does not change materially due to leakage. It will be noticed 
 that bubbles of air come from the pigments very rapidly at first and that this 
 
138 Specific Gravity Determinations 
 
 action gradually decreases and finally stops altogether. The time required 
 for complete removal of air varies from 80 minutes to two hours, depending 
 upon the nature of the pigment. When no more bubbles can be seen, it is 
 assumed that all the occluded air has been given off and that the pigment 
 is thoroughly wet with kerosene. Air can then be slowly admitted to the 
 desiccator by means of the pinchcock. 
 
 7. The pyknometer shall be taken from the desiccator and filled with 
 kerosene, care being taken to add a suflicient quantity to prevent the forma- 
 tion of air bubbles when placement of the thermometer is made. ‘The 
 thermometer shall be placed in the water bath, which shall be cooled with ice 
 to a temperature of between 10 and 13°C. The pyknometer shall be placed 
 in the bath and be permitted to come to constant temperature. ‘The pykno- 
 meter thermometer or capillary tube shall then be inserted. Enough warm 
 water shall be added to the bath to raise the temperature suddenly to about 
 14.5° C. in order to expand the kerosene and prevent it from creeping down 
 the capillary and admitting a small amount of air. The bath shall be allowed 
 to come to a temperature of 15.5° C. The capillary tube shall be wiped with 
 filter paper and the cap put on. All temperatures on the thermometer in the 
 bath shall be read, but not on the thermometer in the pyknometer. The 
 pyknometer shall be removed from the bath and dried. It shall then be 
 allowed to stand for 30 minutes to enable it to come to room temperature, 
 and weighed. 
 
 Notre.—It is advisable to allow the pyknometer to stand approximately the 
 same time before each weighing so as to compensate for slight errors due to 
 evaporation at the joints. 
 
 8. The specific gravity shall be calculated from the formula : 
 
 Specific Gravity of Pigments a 
 (P+ K)—F 
 In which K = Weight of the bottle filled with kerosene only ; 
 P = Weight cof pigment used; 
 fF = Final weight of the bottle with pigment and kerosene; 
 S = Specific gravity of the kerosene used. 
 
 9. Before a new desiccator is used for the first time, it shall be wrapped 
 in a towel and tested under the vacuum to be used, great care being exer- 
 cised in handling the desiccator when the vacuum is on, as any sudden jar” 
 may cause it to collapse. 
 
 10. It has been found convenient to run six samples at one time, the 
 desiccator specified being of the proper size to accommodate this number. 
 
 METHOD B: FOR TESTS REQUIRING HIGHEST ACCURACY. 
 
 APPARATUS 
 11. Apparatus—The apparatus shall consist of the following: 
 (a) A pyknometer as shown in Fig. 48 (a) or (b) having a capacity of 
 00 ce. ) 
 (b) A water bath consisting of a vessel filled with sufficient water to Der 
 
 mit of only a very gradual rise in temperature and equipped with a stirring 
 device, preferably air-blown. 
 
 Re eRe, i i i) ad 
 
Specific Gravity Determinations 139 
 
 (c) A glass bell jar with a two-hole rubber stopper. Into one hole of the 
 stopper is fitted a separatory funnel with a well-ground stop-cock ec, Fig. 49, and 
 with the lower tube extending into the pyknometer (just below the opening of 
 the side arm in Fig. 49 (a). Into the other hole of the stopper is fitted a glass 
 tube with a well-ground 3-way stop-cock, Fig. 49, the tube connecting with the 
 vacuum pump ¢, Fig. 50. The bell jar rests on a sheet of rubber, cemented or 
 vuleanized to a glass or iron plate. With stop-cock ¢ closed and stop-cock d 
 opened to the pump, the system shall withstand and maintain a vacuum. 
 
 Norre.—A suitable desiccator may be substituted for the bell jar. 
 
 = 
 é . 
 
 (d) A thermometer having a range of from 0 to 60° C. graduated in 0.1° C 
 (e) A high vacuum pump e, Fig. 50. 
 
 (f) An open-tube manometer f, Fig. 50, as described in Section 1 (c¢). 
 (g) A storage bottle h, for kerosene or other wetting liquid. 
 
 Stop - Cock 
 d 
 
 deparatory Funnel -----3 
 Stop-Cock G --------- 
 
 Bell Jar 
 
 FIGURE 49 
 
 PROCEDURE 
 
 12. Procedure.—The pyknometer containing the weighed sample of dried 
 pigment shall be placed under the bell jar. Close stop-cocks ¢ and d, start the 
 vacuum pump and gradually open stop-cock d@ to the pump. When the air 
 has all been removed, with a vacuum of 1 mm. maintained, fill the separatory 
 funnel with kerosine, close stop-cock d, and at once gradually open stop-cock c, 
 adding sufficient kerosene to completely cover the pigment. Stop the pump 
 -and release suction at d. Finally fill the pyknometer with kerosine and com- 
 plete the test as described in Sections 7 and 8. 
 
 NOTES 
 
 1. Before a new bell jar (or desiccator) is used for the first time, it shall be 
 tested under a vacuum as described in Section 9. 
 
 2. Stop-cock ¢ must be well-ground and should be lubricated with castor oil 
 or glycerin. See precautions in Section 19 under Method C concerning the 
 necessity of testing the system for leaks before making a determination. 
 
 3. With certain pigments that are not wetted well with kerosine, the sub- 
 stitution of turpentine has been found very efficient. However, when turpen- 
 tine or any other liquid having a high evaporation rate, is used, a pyknometer 
 of type a or b, Fig. 48, is not satisfactory. on account of losses around the 
 ground-glass joints. When using such liquids as turpentine, the bottle (as a 
 
140 Specific Gravity Determinations 
 
 pyknometer) and apparatus as described in Section 18 under Method C should 
 be used, except that instead of attempting to measure an accurate volume of 
 the liquid from the burette, the bottle (plus the sample plus the wetting liquid) 
 is finally weighed as in Method B. 
 
 FIGURE 50 
 
 Apparatus Assembly for Determining Specific Gravity of Pigments, 
 
 METHOD C: RAPID AND ACCURATE TESTING OF SINGLE SAMPLES 
 APPARATUS 
 
 13. Apparatus.—The apparatus shall consist of the following (see Fig. 50): 
 
 (a) A 100-ce burette with a 75-cce. bulb in the upper part and the lower 
 part (25 ce.) graduated in 0.05 ec. (see Fig. 51), 
 
 (b) A special 100-ce. graduated flask, b, Fig. 50, with ground-glass stopper. 
 The flask shall be thick enough to withstand and maintain a vacuum and 
 Should weigh less than 35 g. The neck of the flask should be graduated in 
 0.05 ce. between the 99 and 100-cc. marks. The dimensions of the flask are 
 shown in Fig. 50. 
 
 (c) A tightly-ground stop-cock c, in the burette a. 
 
 (d) A 3-way stop-cock d, connecting with the vacuum pump e. 
 
 ( e) A high vacuum pump e, of the type requiring no preliminary or “back- 
 ing” pump. 
 
 Nore.—The “Hyvac” oil pump is satisfactory. 
 
 (f) An open-tube manometer f, Fig. 50, as described in Section 1 (ce). 
 
Specific Gravity Determinations 141 
 
 ——a pee NY en 
 
 Not 
 less 
 | than 
 
 | 
 x 
 
 Burette: 
 
 less 
 than 
 13 cm Jom. 
 
 | Not 
 
 Geissler, Straight. 
 
 Glass Stopeock, 
 
 Ground Accurately. 
 Total Capacity, cc.... 100 
 Capacity of Bulb, ec.. 0-75 
 Graduated, cer. a7. 75-100 
 Subdivisions, cc...... 1 /20 
 Rate of Outflow, 
 
 about 2 Min. 
 
 ~ 
 
 1. .5.25cm 
 if Opherica 
 
 Not | 
 less Ve. 
 than 
 Jom. 
 
 | 
 
 l..-NoF less than 60cm:--->| 
 
 | 
 
 Bae cep cicaremeseeeres) NOR iiore then 90cm. Por Win gion Tae wage | 
 
 Tolerance: 
 
 Total Capacity...0/10 ec. 
 Graduate Portion .0.08 ce. 
 Markings on Graduations 
 should be in Conformity 
 with the Bureau of Stand- 
 
 | 
 
 ey) ne ards Circular No. 9. 
 SE 
 35 Yi 
 ra 
 FIGurRE 51 
 
 100-ce. Glass Burette. 
 
 Norr.—The difference in levels of the mercury in the manometer when the 
 system is in operation, subtracted from the barometer reading taken at the 
 same time, gives the vacuum of the system in millimeters of mercury. The 
 difference between the barometer and the manometer readings should not ex- 
 ceed 1 mm. 
 
 (g) A thermometer, g, having a range of from 0 to 60° C. graduated in 
 
 1s een OF 
 (h) A storage bottle h for kerosine or other wetting liquid. 
 
 PROCEDURE 
 
 14. Standardization of Apparatus.—The flask shall be connected to the 
 burette and pump by means of a two-hole rubber stopper. The system shall 
 be evacuated with stop-cock c closed until the pump maintains a vacuum of 
 1 mm. in the flask (this requires only a few minutes). Close the 3-way stop- 
 cock d for 30 seconds, and again open to the pump. There should be no appreci- 
 able change in the mercury levels in the manometer, indicating that the system 
 beyond stop-cock d is tight. With the vacuum still maintained, fill the burette 
 from the top with kerosine, adjusting the level to the zero mark with a piece 
 of capillary tubing. Now close stop-cock d and then carefully open stop-cock ¢, 
 admitting about 75 cc. of kerosine into the flask. Open stop-cock d to the air, 
 thus releasing the vacuum in the flask, and fill with kerosine to.a definite mark 
 on the neck of the flask. Read the burette, calling this reading K (the volume 
 of the flask). 
 
142 Specific Gravity Determinations 
 ES 
 15. Method.—The flask shall then be cleaned with ether, dried, and weighed. 
 A glass counterpoise having the same superficial area and treated the same 
 way may be placed on the opposite pan in the balance. A quantity of the dry 
 pigment to be tested shall be transferred to the flask by means of a clean, dry, 
 glass funnel whose stem reaches to the bottom of the bulb. A piece of stiff 
 nickel wire is convenient in pushing the powder down the stem. The bulb of 
 the flask should be nearly filled with the sample which, however, should occupy 
 a volume of less than 25 ce. after all air is expelled. Greater accuracy may be 
 obtained with a large sample than with a small one. The inside stem as well 
 as the entire outside of the flask should be wiped with a clean piece of dry, 
 lintless cloth. The flask and pigment shall then be weighed and the weight of 
 pigment computed by deducting the weight of the empty flask. With the 
 burette clean and dry, but with the stop-cocks well lubricated (castor oil or 
 es the flask shall be attached to the evacuating system as shown in 
 ig 50. After closing stop-cocks ¢ and d, the pump shall be started and stop- 
 ie d carefully opened to the pump. Evacuation shall be continued until 
 the pump maintains a vacuum of 1 mm. in the flask, or until all the air is ex- 
 pelled from the system. The burette shall then be filled from the top as 
 described in Section 14, stop-cock d closed, stop-cock ¢ gradually opened and 
 kerosine added until the pigment is covered. The flask shall be tapped genetly 
 to dislodge any air bubbles. The pump should be stopped, stop-cock d opened 
 to the air, and the flask filled up to the same mark as was obtained in de- 
 termining its volume. The volume of kerosine required may be designated X. 
 Note the height of the liquid in the burette to the nearest estimated 0.01 cc. 
 
 Norr.—The removal of all air can not be stressed too greatly, as the pres- 
 ence of air will cause low results. 
 
 16. Calculation.—The specific gravity shall be calculated from the formula: 
 
 eS hety Gee em Water 
 Specific Gravity of Pigment “For 
 where 
 S = weight of pigment used; 
 K =volume of kerosine required to fill the flask when empty; 
 = volume of kerosine required to fill the flask when the pigment is 
 
 present. 
 
 < 
 
 17. Temperature.—Since the specific gravity of a pigment is only slightly 
 affected by temperature, such variations as occur under normal conditions in 
 a room would not materially affect the results. Care shall be taken, however, 
 that the temperature of the liquid after transferring to the flask is approxi- 
 mately the same as it was when in the burette. 
 
 18. Wetting Mediwm.—While kerosine has been found to be a good wetting 
 medium, any liquid which does not have a high evaporation rate may be used. 
 The liquids are interchangeable, as no constants on them need be determined. 
 Hence, a pigment containing a dye which is slightly soluble in kerosine could 
 be run with another liquid in the same apparatus without special standardiza- 
 tion for that liquid. Operators are cautioned against the use of water as it 
 causes considerable frothing with certain pigments. 
 
 19. (a) Precautions—Care shall be taken that the burette atop aces is 
 well ground in order to prevent leakage of kerosine. Castor oil is suggested 
 as the stop-cock lubricant. ' 
 
Specific Gravity Determinations 143 
 
 (>) Since in determining both K and X, the tip of the burette and bore of 
 the stop-cock plug are empty, no correction is needed; stop-cock c, however, 
 should be so well ground that under a vacuum of 1 mm. for 30 minutes no leak- 
 age of kerosine takes place. The usual sources of error are failure to remove 
 all the air from the pigment and leaks in the system. The minimum amount of 
 rubber tubing should be used anywhere in the system, and wherever this is. 
 used the joints between rubber and glass should be coated with a melted mix- 
 ture of beeswax and rosin. 
 
 (c) In cleaning the flask of kerosine only, a rinsing two or three times with 
 ether followed by dry air (dried over sulfuric acid and calcium chloride) is 
 sufficient. When pigment is also present, both pigment and kerosine should 
 be shaken together and then emptied. This should be followed with ether 
 until no more pigment is removed. Some filter pulp (macerated filter paper ) 
 and water (with or without some glass beads) should be added and shaken 
 vigorously. Repetition may be necessary. The flask should then be rinsed 
 with distilled water and either dried in an oven or rinsed with alcohol and 
 ether followed by dry air. In determining specific gravity by this method, there 
 is no reason why the flask if made of Pyrex glass can not be heated, followed 
 by cooling during evacuation if such heating has no effect on the sample. 
 
 Whirling Method.—Mr. Zieglemann* in connection with 
 the determination of the specific gravity of pigments has re- 
 cently utilized the centrifuge in place of the vacuum apparatus. 
 A special brass cup 3 1/8 inches high and 1 1/4 inches dia- 
 meter, volume about 50 ce. fitted with a one hole brass stopper 
 is provided. The volume of the cup to the top of the hole in 
 the stopper is determined. Then to the cup containing about 
 29 ec. of wetting liquid, a suitable amount of pigment is 
 added. After the pigment is entirely wetted the cup is placed 
 in the centrifuge and whirled for about three minutes. The 
 stopper is then put in place and liquid added from the burette 
 until the vessel is filled. The calculations are the same as 
 
 those of the A. S. T. M. method and the author claims good 
 agreement. 
 
 Specific Gravity of Mixed Pigment.—For calculating the 
 specific gravity of a mixture of two pigments in definite pro- 
 portions, when the specific gravities of each are known, use 
 this formula: 
 
 100 +( = a = )- specific gravity of mixture. 
 
 Where P and P’ are the percentages of the two pigments and S and 
 S’ are their respective specific gravities. 
 
 * Paint, oil and Chemical Review Aug. 4, 1927. 
 
144 Specific Gravity Determinations 
 
 Example: 
 100 + (stig)- 
 é 
 100 
 100 + (8.43 + 14.56) = 90 OG 
 
 4.35 (specific gravity of mixture). 
 
 Average Specific Gravity Data. For the convenience of 
 manufacturers who do not have facilities for making specific — 
 eravity determinations on various types of pigments, and who 
 desire a chart showing the average specific gravity of many of 
 the commonly used pigments, a special table has been pre- 
 pared. It should be pointed out, however, that the specific 
 gravity of even such colors as are termed chemically pure, 
 such for instance as chrome green, may vary to a great extent. 
 This is due to the fact that these greens may contain a small 
 or a large percentage of blue, and in some instances varying 
 amounts of lead sulphate. This variance in composition, 
 therefore, of even chemically pure colors, 1s sufficient to warn 
 the paint grinder that serious mistakes may occur in caleula- 
 tions made on average specific gravity figures of certain col- 
 ored pigments. <A chart is also presented showing the specific 
 gravity and bulking values of many liquids that are used in 
 paint and enamel manufacture. 
 
 Weight One 
 per Pound 
 Specific Solid Bulks 
 Gravity Gallon Gallons 
 ALUMINUIn “Dusts ck eee 2.64 21.99 0.04548 
 American Blue (Ferrocyanide Blue)+ 1.85 15.41 06489 
 Antimony" OF10Gs), si. set eee 3.73 47.73 .0209 
 Darytes s.r Cee oe Oe ae 4.45 37.07 .02698 
 Basic Carbonate White Lead...... 6.81 06.73 « .01768 - 
 Basic Sulphate White Lead...... 6.41 53.40 01873 
 Brown Oxide (50% Fe,0,)........ 3.35 27.91, .03583 
 SAN CY 2c we he eee | = 2,62 21.82 04583 
 *Chrome Green: Os ey ane esd eee to. 
 *Chrome Yellow, Os-by..6. nents ; *6.00 
 Ohrominum (Oxide sioss- ee 4.95 41,23 02425 
 BT DOn s BIS Gi ecu s, i ceten aden eee 1.81 15.08 .06631 
 ‘* Diatomaceous’ Marth .5..0 ss ceen 1358 
 
 * These will vary widely according to composition required for shade or 
 tone and character of base. 
 
 + Chinese, Milori or Prussian. 
 
 **These will vary widely. 
 
Specific Gravity Determinations 145 
 
 Weight One 
 
 per Pound 
 
 Specific Solid Bulks 
 
 Gravity Fallon Gallons 
 
 MMSTEME EG Foe at ofa cbs. eichs ct sale se ene 2.64 21.99 04548 
 
 DIR TN ee) a cc Ses Sas 0 eas .8 0 oe 2.86 19.66 05086 
 
 ES Wot 2 a REET 29 O1 04365 
 
 Ferric Oxide (98% Fe,O,)........ 5.15 42.90 base L 
 
 ieee mimeral Willer.............. raw PVE 04431 
 
 PURIST ESOL ioe ore gas G6 + ces esas 2 ac Lyte: 14.83 06743 
 
 Indian Ked (90% Fe,0,)........:. 4,92 40.98 02440 
 
 IEE TLRS, Teor b0, ela g < woe'e o's 2.85 23.74 04212 
 
 SSE iE S08 Sa a 11.09 92.38 .01082 
 
 PPC TOOL -GTECD . , 6 ccc ccc ec ee woe 2.80 23.382 .04288 
 
 (ONCE Se AS a a a 9.40 78.3¢ .01277 
 Lithopone (50% ZnS) High 
 
 NACE Gye S08 OEE ia 4.20 34.99 02858 
 Lithopone (28% ZnS) Regular.... 4.30 35.82 02792 
 RO Heit a ceo favwc a on « #0 00 4070 2.80 2o.08 04288 
 REMC VITO icc cn po cate es pace os 8.80 To.0 01364 
 Mineral Brown (45% Fe,0O,)...... 3.34 27.82 03595 
 Para Red 10% (on Lime and Bari- 
 
 MRNA SeR NRTA e Senn ooo nicl adn 9% ace 2.65 22.07 04531 
 eee or ata PONG. 6 fe sek ce es 1.50 12.50 O800 
 Pure Toluidine Red Toner........ 1.49 12.41 OSO058 
 ON GIRS G0 ee 8.80 13.00 .01364 
 Red Oxide (40% Fe,0,).......... 3.45 28.74 038479 
 mensOxide. (959 We,O........6.. 4.95 41.23 02425 
 MITE STIETO ce ee got o-e okies ces we 3.99 32.90 03040 
 BEEN Po cc cies ce eles lke ee ear 27.24 038671 
 Say ie Se 7 2.65 22.07 04531 
 OR Is Oa i er 2.84 23.66 04227 
 Titanium Oxide (100% TiO,)..... 3.94 32.82 03047 
 Titanox (Barium Base).......... 4.30 35.82 02792 
 Tiuanox (Calcium Base)......... 3.13 26.07 .03836- 
 BRIM ees cletala kati edle < siesacs ss 3.95 32.90 .03040 
 WT POAT Ee. SIG1UC 6 dies Sane es ce ss 2.85 19.58 05107 
 USES oe Tap i a ~ 3.80 31.65 .03160 
 MA irre eed <6 soc Se 2.68 Lap seed 04480 
 *Venetian Red (20% Fe,O;)....... 3.05 25.41 03935 
 ee ire ego's hee ss Apache ahirnage™ oan pg | ao 04431 
 eA ST tM AS cry bias 6 o's oe se sss 7.06 58.81 .01700 
 OPN SG 2: leg a er 5.66 47.15 02121 
 Zane wxide, Leaded 35%.......... 5.95 49.56 02018 
 PROMS ws a clcs os eee co ee owe ke 4.00 39.02 .03001 
 
 Apparent Density of Pigments.—Some laboratories con- 
 sider of importance a property which may be called ‘‘appar- 
 ent density,’’ which is the mass of a certain volume of loose 
 ary pigment. Although not standardized the following meth- 
 ods of determination have been used at this laboratory: A 
 eylinder (about 100 cc.) is used. The levelled off volume of 
 the cylinder is determined. Enough of the pigment sample 
 to fill the cylinder about three times is passed through a 10 
 mesh sieve by gently stirring with a spatula. From 5 to 7 
 
 *These will vary widely according to composition required for shade or 
 tone and character of base. 
 
Specific Gravity Determinations 
 
 146 
 
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Specific Gravity Determinations 147 
 
 loads of the spatula or a small scoop are then used to fill the 
 eylinder. The contents of the cylinder is then levelled off 
 and the weight of added pigment determined. Precautions 
 must be taken to avoid jarring the cylinder while filling it. 
 
 Variations in the method are, (1) the use of a graduated 
 eylinder in which case the actual volume of 6 spatula loads 
 is noted; (2) filling as in (1), packing the pigment by drop- 
 ping the cylinder 100 times from a height of 10 cm. onto a rub- 
 ber stopper and then noting the volume and (3) sieving the 
 pigment several times instead of once before filling the cylin- 
 der. The following results on a series of lamp blacks illus- 
 trate the methods: 
 
 TABLE 30 
 
 APPARENT DENSITY OF LAMP BLACKS. 
 (Grams Pigment Occupied by 1000 cc.) 
 
 Sample No. 1 No. 2 No. 3 No. 4 No. 5 
 Method 1. 126 124 116 124 123 
 Cylinder filled and leveled 128 122 124 Lass 128 
 off. 129 125 123 126 129 
 Mean (128) (124) (121) (124) (127) 
 
 Method 2. 
 6 loads (about 100 ce.) in 131 126: 124 126 128 
 a 250 cc. glass cylinder. 134 128 120 126 isl 
 Mean (133) (127) (122) (126) (130) 
 
 Method 3. 
 
 The contents of cylinder in 
 Method 2 packed by drop- 
 ping 100 times from a 
 
 height of 10 cm. onto a 200 191 192 197 201 
 rubber stopper. 206 198 193 194 203 
 Mean (203) (195) (193) (196) (202) 
 
 Method 4. 
 
 Method No. 1 except that 122 119 116 120 121 
 the pigment was sieved 125 120 118 118 124 
 5 times instead of once. 126 118 120 118 128 
 
 Mean (124) (119) (118) (119) (124) 
 
 Method for Determining Specific Gravity of Paint Liquids. 
 The specific gravity of a liquid may be determined with sufh- 
 cient accuracy with a Westphal balance or a standardized hy- 
 drometer and thermometer in the customary manner, making 
 any necessary corrections for temperature. For viscous blown 
 or bodied oils or for mixed paints, satisfactory results may be 
 obtained, when a quantity is available by weighing a liter of 
 the oil or paint in a graduated tared liter flask. When only 
 small amounts are available or when great accuracy is desired 
 the method below* should be used: 
 
 *The above described method is adopted from the proposed tentative 
 standard test for the specific gravity of road oils, road tars, asphalt cements, 
 and soft tar pitches. See Proc. Amer. Soc. Test. Mater., Vol. XX, 1920. 
 
148 Specific Gravity Determinations 
 
 The specific gravity of an oil is expressed as the ratio of the 
 weight of a given volume at 25° C. to that of an equal volume 
 of water at the same temperature. The determination of 
 specific gravity, in the case of heavy bodied oils especially, is 
 
 7 em we re ee we a ae 
 me a ee ee ee 
 
 FIGURE 52 
 
 Pyknometer 
 or weighing 
 bottle. 
 
 best made in a straight walled glass tube pyknometer approxi- 
 mately 70 mm. long and 22 mm. in diameter, carefully ground 
 to receive an accurately fitting glass stopper with a hole of 1.5 
 to 1.7 mm. bore in place of the usual capillary opening. The 
 stoppered tube should have a capacity of about 24 ec., and 
 when empty should weigh not over 35 grams. 
 
 The type of bottle described is illustrated. 
 
 The pyknometer with stopper is first calibrated by weighing 
 it, clean and dry, upon an analytical balance. This weight is 
 called A. It is then filled with distilled water at a temperature 
 of 25° C., the stopper firmly inserted, all surplus moisture 
 wiped from the surface with a clean, dry cloth, and again 
 weighed. This weight is called B. 
 
 For the determination of the specific gravity of an ordinary 
 oil or paint liquid, the material shall be brought to a tempera- 
 ture of 25° C. and poured into the pyknometer until it is full, 
 using care to prevent the inclusion of air bubbles. The stop- 
 per is then inserted and the excess of liquid forced through the 
 opening is carefully removed with a clean, dry cloth. The 
 pyknometer and contents are then weighed, and this weight is 
 
 “a 
 
Specific Gravity Determinations 149 
 
 ealled C. The specific gravity of the material may then be ecal- 
 eulated from the following formula. 
 
 GAs 
 
 B—A_ 
 
 Specific gravity = 
 
 When the specific gravity of extremely heavy bodied oils or 
 blown oils, or certain paste products is to be determined, the 
 viscosity of these materials may make the previously described 
 method inapplicable. Such materials should first be gently 
 warmed, using care to prevent loss by evaporation. When 
 fluid, enough is poured into the clean, dry pyknometer to about 
 half fill it. Precautions shall be taken to keep the material 
 from touching the sides of the tube above the final level and 
 to prevent the inclusion of air bubbles. It is advisable to 
 shightly warm the tube before filing. The pyknometer and 
 contents are then cooled to room temperature and weighed 
 with the stopper. This weight is called C. The pyknometer is 
 next removed from the balance, filled with distilled water, and 
 the stopper firmly inserted. It is then completely immersed 
 for not less than 30 minutes in a beaker of distilled water 
 maintained at 25° C., after which it is removed and all surplus 
 water wiped off with a clean cloth. It is immediately weighed. 
 This weight is called D. The specific gravity of the material 
 may be calculated from the following formula: 
 
 A) 
 
 Brouitt era ViLYos oe ce oe es a eS 
 cope CRs Apne at) 
 
150 
 
 Specific Gravity Determinations 
 
 Leanne eee ee ees aacaacaacaacaaacaaaaacaaaaaaaal 
 TABLE OF BULKING AVERAGES OF VARIOUS LIQUIDS 
 
 Specific 
 
 Gravity 
 ACCTORO a Sul pas Sew Sale ese bon 
 Amyl Acetate (85-88%) .........+- 0.8600 
 Amy: Alconol 5305.05 5 Vs Dior otal ae .8266 
 NRSOY Meals aes dae Pirie a nied eee 0.8019 
 Aleohol (No. 1 Denatured)....... 836 
 Benzine (62°) ii. So eee bee 745 
 Benz. OR es hee ee a ee 883 
 Butyl. Acetater cuss ae s paarncae 0.8763 
 Bitty! Alcoholics ee ein 64 wie sce ees 8057 
 Camphor ih. 0k oie se <a a ee le ee .963 
 Carbon Tetrachloride. .«.......... 1.583 
 Castor OF “CBIOWIN 60 eins oe .9942 
 Cyclohexanoly.. 06 or nde ves on oie .9624 
 Di Acetone Alcohol............... RS 4 
 Diamyl Phthalate... voni ne ae 1.0252 
 Di. Butyl Phthalate... ic 22. +s 3 oe 1.04 
 Di: Butyl Tartrate. os n-ne eee 1.08 
 Diethyl “Oxalate ges is cess van eee 1.0801 
 Iiethy] Phthalate... 5 si. 5 os steele 1.1224 
 Esterified Rosin (Ester Gum).... 1.08 
 Ethyl Acetate (85-88%).......... 0.8883 
 Ethyl Acetate (99-100%)......... 0.9001 
 Ethyl Alcohols. seas cee ptetee .7850 
 Ethyl Lactate, cic. cee eee 1.0384 
 Purtarake 3 os0 we ie ee eee 1.16 
 Frsel Oi; “Retined 3 .. aac Soa 0.8139 
 Grain, \AlGOnOII <6 teste a uses .T85 
 Hereasol: vous eeatietias so eke eee .893 
 Hexol .R (Solid. Resin)... a eee 
 isopropyl Aleouol..2 cacesew eee 78 
 Lindol (Tricresyl Phosphate)..... 1.17 
 Linseed Oil, Boleds ....402 4.000 «eee 4942 
 Linseed Oil, Heavy Bodied........ : .98 
 Linseed: Oil, Raw ws <s css 32 
 +Liquid<Paint Drier. €)..55 2 85 
 {Mineral - Spirits. ices «os eel eee T73 
 {i.ixine Varnish... issn oaleoeeee .905 
 Nitrocellulose, CDry ) <> .10see ee Sina 
 *RESINS 4. hee ed oe ee 1.05 
 Solvent Naptha (160*). 4. oe ae 902 
 soya Bean Oil, Raw.%W.5.002e. 03 ou .929 
 TORQ! | sais acaiats Sane Ole see eee S72 
 Tung Oil, zRawWiiw ess sok eee .940 
 Turpentine 74.5 .4)h4 9 28 ea eee ees 867 
 Wood Alcohol (Methyl)......:... io 
 32 0z. Solution L. V. Nitrocellulose 
 In Butyl Acetate... wot ee 953 
 UPCR Sk is Dae tae ee 1.323 
 DUO Fs eo rs as ce re ae S76 
 
 Weight One 
 per Pound 
 Solid Bulks 
 Gallon Gallons 
 6.639 1506 
 Take 0.1396 
 6.886 0.1452 
 6.68 0.1499 
 6.964 1486 
 6.206 1611 
 7.355 .1359 
 7.30 OAS71 
 6.711 0.1492 
 8.022 0.1246 
 18.190 0.0758 
 8.247 pide 
 8.017 0.1247 
 7.664 1305 
 8.54 OT17I 
 8.663 1154 
 8.996. 1112 
 9.00 0.1112 
 9.35 0.1070 
 8.996 102 
 7.40 0.1351 
 7.90 0.1334 
 6.538 0.1529 
 8.65 0.1160 
 9.663 0.1035 
 6.78 0.1473 
 6.539 .1529 
 7.4389 1344 
 11.08 .09025 
 6.497 0.1539 
 9.746 1026 
 7.847 1274 
 8.163 1225 © 
 7.764 .1288 
 6.681 1497 
 6.456 1549 
 7.539 1326 
 ce 105 
 8.747 .1148 
 7.514 13381 
 7.739 1292 
 7.264 dole 
 7.830 me lef Ws 
 1 .Qae .1385 
 6.589 .1518 
 7.914 .1264 
 11.02 0.0907 
 527 0.1370 
 
 + These liquids will vary greatly in specific gravity. Grinders should ae- 
 
 termine the figures for the products they use. 
 
 Moreover, different batches of 
 
 liquids given above may vary slightly in specific gravity. 
 * Most Resins are of the approximate value given above. 
 
CHAPTER X 
 
 DETERMINING COARSE PARTICLES IN PAINT PIGMENTS 
 
 The method originally devised for this purpose by the 
 writer and published in the earlier editions of this volume has 
 recently been adopted with some slight changes by the Amert- 
 ean Society for Testing Materials. It is presented below. 
 This specification is then followed by data on special manip- 
 ulative requirements worked out in this laboratory. 
 
 A. 8S. T. M. STANDARD METHOD OF TEST FOR 
 COARSE PARTICLES IN PAINT PIGMENTS 
 
 1. The apparatus shall consist of a 3-in. No. 325 (44 micron) sieve conform- 
 ing to the Standard Specifications for Sieves for Testing Purposes (Serial 
 Designation: E 11) of the American Society for Testing Materials.* A 3-in. 
 No. 325 (44 micron) sieve for comparison purposes should be retained in the 
 laboratory as a standard. Whenever a new Sieve is secured, a practical test 
 of its accuracy should be made by running on it and on the standard sieve a 
 pigment that has a considerable percentage of coarse particles. A reserve 
 stock of such pigment should be kept for this purpose. 
 
 Il. PROCEDURE 
 
 2. The sieve shall be weighed on an analytical balance, the weight being 
 recorded in a figure carried to the third decimal place. The sieve shall then 
 be wet on both sides with the liquid to be used for wash purposes. 
 
 3. The sample of the pigment to be tested shall be weighed. For most pig- 
 ments 10 g. will be the proper quantity. For black pigments of low specific 
 gravity 2 g. will be sufficient. For pigments like Prussian blue and graphite, 
 3 g. are generally used. The weighed samples of pigments shall then be trans- 
 ferred to the sieve. 
 
 If the pigment is one that is difficult to wet with the wash liquid, the 
 quantity weighed out should first be placed in a beaker containing some of a 
 liquid that easily wets the pigment and that is miscible with the wash liquid. 
 For example, if water is to be used as the wash liquid, alcohol may be used 
 as the wetting medium. The pigment is then gently stirred with the wetting 
 
 * Sieves 3 in. in diameter will be received by the U. S. Bureau of Standards 
 for test. The cloth will be tested to determine whether or not it conforms to 
 the specifications for cloth of the U. S. Standard Sieve Series. The specifica- 
 tions for the sieve frame are now being prepared. No. 325 (44 micron) cloth 
 of the U. S. Standard Sieve Series should be made of wire 0.036 mm. (0.0014 
 in.) in diameter, a tolerance of 15 per cent under and 35 per cent over being 
 allowed on this diameter. The average opening between adjacent parallel 
 wires should be 0.044 mm. (0.0017 in.), the tolerance being 8 per cent with 
 the additional limitation that the maximum opening shall not exceed 0.044 mm, 
 by more than 90 per cent. Sieves whose cloth conforms to these specifications: 
 and whose frames are in accordance with specifications now in preparation 
 will be marked with the letters ‘‘BS” and the year in which the test is made. 
 A report will be issued for each sieve submitted, a nominal fee being charged 
 for this test. 
 
152 Coarse Particles in Pigments 
 
 liquid and the contents of the beaker transferred to the sieve. Where small 
 particles of pigment are retained on the stirring rod or walls of the beaker 
 they may easily be removed with the brush. 
 
 4. The sieve shall then be held under a tap delivering about 300 to 500 ce. 
 of wash liquid per minute. By slightly shaking the sieve, the pigment will be 
 rapidly carried through. <A soft camel’s hair brush may be used in aiding 
 the operation. If the sieve is held at a slight angle so that the pigment will 
 gradually collect at one edge during the washing process, and then rotated, the 
 pigment may be brushed out rapidly, with no risk of clogging the screen. 
 
 5. After the majority of the finely divided portions of the pigment has 
 passed through the sieve (from 2 minutes to 1 hour, according to Kind of pig- 
 ment), the sieve shall be placed in an 8-in. porcelain dish containing 250 ce. of 
 the wash liquid. The sieve will thus be covered to a depth of about ¥% in. 
 The pigment remaining on the sieve shall be brushed with a soft 1-in. camel’s 
 hair brush at the rate of two strokes per second during two periods of 10 
 seconds each. The sieve shall then be raised from the dish after each 10- 
 second period to let the liquid on the sieve run through. The liquid in the 
 dish should be changed after every two brushing periods described above. 
 This operation shall be continued until the wash liquid passing over the 
 residue and through the sieve is clear and free from solid particles. 
 
 NotEe.—When the operator thinks he has completed the washing he should 
 catch about 200 ce. of the liquid in a clean 400-cc. beaker, stir vigorously and 
 set the beaker on a black surface in the case of white pigments and a white 
 surface in the case of colored pigments. The washing is not complete until 
 a test as described above fails to show any particles collected about the middle 
 of the bottom of the beaker. 
 
 Occasionally pigments will be found that foam when water is used as the 
 wash liquid. In such instances, during the last washing in the porcelain 
 dish, the use of a liquid that breaks down the foaming and is readily miscible 
 with water, such as alcohol, will usually overcome this difficulty. 
 
 6. The pigment particles adhering to: the brush shall then be washed back 
 onto the sieve and the water below the sieve wiped off. A few drops of 
 alcohol and then of ether should be added to expedite drying. The screen 
 shall be dried for one hour in an oven at 105° C., or on a radiator, cooled, 
 weighed, and the percentage of coarse particles calculated. 
 
 7. For pigments requiring wash liquids such as turpentine, mineral spirits. 
 or kerosine, the wash liquid shall be siphoned from a vessel onto the sieve, 
 finishing with ether to remove the wash liquid adhering to the sieve. 
 
 Discussion of Method.—There are presented below some 
 comments arrived at as the result of the examination of a 
 large number of pigments at this laboratory. Illustrations 
 of the method of running the test are also given. 
 
 If the pigment is one that is difficult to wet with the wash 
 liquid, the quantity weighed out should first be placed in a 
 beaker containing some of a liquid that easily wets the pig- 
 ment and that is miscible with the wash liquid. For instance, 
 if water is to be used as the wash liquid, alcohol may be used 
 as the wetting medium. The pigment is then gently stirred 
 
Coarse Particles in Pigments 153 
 
 with the wetting liquid and the contents of the beaker trans- 
 ferred to the screen. Where small particles of pigment are 
 retained on the stirring rod or walls of the beaker they may 
 easily be removed with the brush. 
 
 For those who desire to investigate the subject further the following 
 references are given: 
 
 The classification of Fine Particles According to Size. By G. W. Thomp- 
 son, Proc. A. 8. T. M., Vol. X, 601 (1910). 
 
 Kolloid Zeitschrift. Vol. 18, page 3348, 1916. 
 
 Rapid Test for Fineness of Paint Pigments. By Dr. C. D. Holley and J. 
 C. Brier. Drugs, Oils and Paints, May 10, 1915. 
 
 Comparative Tests for Fineness of Pigments. By Dr. C. D. Holley. Paint, 
 Oil and Chem. Review, No. 23, 1921. 
 
 Circular No. 90. By H. A. Gardner, Scien. Sec., Educat. Bur., Paint Mfrs. 
 Assn. U. S. 
 
 A Photomicrographic Method for the Determination of Particle Size of 
 Paint and Rubber Pigments. By Henry Green, J. Franklin Inst., 192,637 
 (1921). 
 
 See also “Optical Properties of Pigments,’ H. E. Merwin. Proc. A. S. T. 
 M., Part II, 1917, page 496. 
 
 Occasionally pigments will be found that contain quantities 
 of soft lumps or aggregates of finely divided particles which 
 have been cemented together by moisture or by overheating 
 during the drying process. All of these lumps will not pass 
 through the screen even with brushing, as the brush is too 
 soft to break down the aggregates. Placing these lumps be- 
 tween the fingers and exerting slight pressure on them will 
 readily indicate whether they are single coarse particles or 
 ageregates of fine particles which may be broken down by 
 slight pressure. In the latter instance, the lumps during the 
 processing should be spread out in a glass petri dish and 
 broken down with a spatula, using slight pressure but no 
 grinding action. The contents may then be returned to the 
 sereen with a wash bottle. In this way a great amount of 
 time can be saved and accurate end points and readings ob- 
 tained. 
 
 It was found that certain pigments, such as white lead and 
 lithopone, very often show a cementing together of particles 
 that may be due to the presence of water-soluble metallic salts. 
 Although continued soaking in water would ultimately break 
 up such aggregates, it was thought that the use of water as a 
 wash liquid would be inadvisable. This is due to the fact that 
 oil is used for factory grinding and a similar liquid should 
 be used for pigments having cemented particles, when running 
 a sereen test. For such pigments, therefore, wash lquids 
 
154 Coarse Particles in Pigments 
 
 FIGURE 53 
 Determining Coarse Varticles with Water Method. 
 
Coarse Particles in Pigments 155 
 
 consisting of mineral spirits, turpentine or kerosene have been 
 recommended. Some may still prefer to use water, so results 
 on both are given in the charts. 
 
 (Ets 
 
 FIGURE 54 
 
 Using Mineral Spirits or Alcohol as a Wash Liquid. 
 
 For pigments requiring wash liquids such as turpentine or mineral spirits, 
 use apparatus shown above. This apparatus is also used for determining 
 the fineness of paste paints ground in oil. For paints containing varnish, 
 such for instance as Japan colors, a wash liquid of turpentine, solvent naptha 
 or similar solvents is necessary depending on type of pigment. 
 
 Again, with such pigments as Prussian blue a curious state 
 of hard aggregate formation may be observed. While wash- 
 ing with water would break up such aggregates (peptization 
 sometimes occurring’), and in most instances show a residue 
 
Coarse Particles in Pigments 
 
 156 
 
 FIGURE 55 
 200-Mesh Screen X-50 Unused. 
 
 Standard 
 
 PROM UORULBEER RU ULE TV EF 
 S@hR@eageae: awe aae ee’. wpouwa BS 
 eerrrrrerrr ey 
 Seg huaue. aol acti blr fa 
 
 FIGURE 56 
 
 Standard 325-Mesh Screen X-50. 
 
 Used 4 Times. 
 
 Note Pigment Particles Retained. 
 
Coarse Particles in Pigments 157 
 
 of less than 1 per cent, washing with kerosene or liquids in 
 which these aggregates were not broken up would leave resi- 
 dues as high as 62 per cent. 
 
 In view of the widely varying results when solvents other 
 than water are used, it is probable that no limit can be set 
 for the percentage of residue from Prussian blue, when using’ 
 liquids other than water. The use of mineral spirits will 
 undoubtedly indicate to grinders what blues are best suited 
 for rapid grinding in oil, but until color makers are able to 
 wash and dry Prussian blue in such a manner as to prevent 
 the formation of aggregates, it is probable that no standards 
 within close limits can be set. 
 
 Photomicrographs of Coarse Particles.—Six of the photo- 
 micrographs of the coarse particles in pigments, shown in 
 this chapter were made by a rather novel method discussed 
 in one of the writer’s Articles on Fineness. By this method 
 a very rapid examination of pigment particles can be made, 
 especially if they are of coarse grain. Instead of requiring 
 a long time for the preparation of special slides, special illumi- 
 nation, ete., all that is required is a Victrola or similar talking 
 machine record and a microscope. (See Figs. 57-62.) 
 
 The test is made by rubbing with the finger a portion of the 
 pigment across the grooves of a disc phonograph record and 
 then observing the surface with a microscope. The Edison 
 type of disc has a spiral groove with 150 convolutions per inch 
 of radius. The lines are 1/150 of an inch from center to 
 eenter. ‘The radius of curvature of the souud grooves is 
 4/1000 (.004) of an inch. The average depth of the grooves 
 is 1/1000 inch. - 
 
 One record may be used for several pigments which may be 
 numbered and the records kept in a cabinet for comparison as 
 standards for various subsequent batches of pigments pro- 
 duced or received in the factory. During the procedure of 
 rubbing the pigments into the grooves, characteristic differ- 
 ences are at once noted. Some pigments will feel coarse and 
 gritty. Others will have a soapy or unctuous feeling. For 
 instance, two samples of china clay or barytes which appear 
 to be of equally fine texture when rubbed between the fingers, 
 “may upon rubbing into the record show entirely different 
 characteristics. One pigment may feel soft or ‘‘silky’’ in 
 texture, while the other may feel granular and ‘‘gritty.’’ 
 
158 Coarse Particles in Pigments 
 
 FIGURE 57 
 
 Red Lead 
 Some Particles Are Transparent. 
 
 FIGURE 58 
 
 White Lead. 
 
Coarse Particles in Pigments 159 
 
 Pr tists ga 
 
 FIGURE 59 
 
 Barytes 
 
 FIGURE 60 
 
 China Clay. 
 Note Transparent Particles. 
 
160 
 
 Coarse Particles in Pigments 
 
 NOOR ratte gal baths 
 
 ay 
 
 FIGURE 61 
 
 Calcium Carbonate. 
 
 FIGURE 62 
 
 Bone Black 
 Note Angular Hard Particles. 
 
 ee 
 
Coarse Particles in Pigments 161 
 ee 
 Microscopic examination of the surface will then immediately 
 disclose the reason for this phenomenon. 
 
 Most pigments are made up of particles of varying size. 
 The large particles are often covered with fine ones. When 
 such pigments are placed on a record, the rubbing action 
 forces the large crystals between the grooves and arranges 
 them with their facets parallel to the face of the record. The 
 fine particles are at the same time wiped from the larger 
 erystals, so that the form of the latter is disclosed. With fume 
 pigments, the very fine particles as well as the agglomerates 
 may be shown. The relative degree of color, whiteness, and 
 hiding power of the pigments are to some extent also tudi: 
 
 beds 
 
 For the microscopic examination it is advisable to use a 
 32 mm. objective and a 12.5X eye-piece. Greater depth of 
 focus is thus obtained and the magnification is sufficient. It is 
 usual to look at the dise obliquely in order to get the specular 
 reflection of the light. 
 
 For a photographic record of the appearance of the pig- 
 ments, great care should be taken that a strong light is pro- 
 vided and that a water cell is interposed for absorbing the 
 heat rays of the ight. Otherwise the light, impinging upon 
 the record at one point, will cause a melting down of the 
 grooves. Photography then becomes impracticable. 
 
 Gallie-Porritt Apparatus for Coarse Particles—An arti- 
 cle entitled ‘‘An Apparatus for the Separation of Grit and 
 Coarse Particles from Fine Powders,’’ by G. Gallie and Por- 
 ritt® describes a simple form of apparatus for this purpose. 
 The principle of the method consists in suspending a pigment 
 in water and supplying the mechanical force necessary to 
 secure the passage of the fine particles through a sieve, at 
 the same time breaking down any lumps present, by a jet of 
 water under pressure. For detailed reference to this appa- 
 ratus, the above publication may be consulted. 
 
 Thompson Classifier for Paint Pigments.—An interesting 
 apparatus for determining the coarse particles in paint pig- 
 ments has been developed by G. W. Thompson of the National 
 Lead Co., who described it in a paper entitled ‘‘The Classifi- 
 cation of Fine Particles According to Size’’ in the Proceed- 
 
 * J. Oil & Colour Chemists Assn., Sept., 1926. 
 
162 Coarse Particles in Pigments 
 
 ings of the A. 8. T. M., Vol. X, 1910, from which the following 
 information is taken. <A diagram of the apparatus is shown 
 in Fig. 63. As will be noted from the illustration, it consists 
 
 +o SEP 2 Beg 
 
 [= (MRR o)! fi! a} 
 ff 
 
 Vi 
 HY Att U 
 , 
 j 
 y 
 
 FIGURE 63 
 
 Diagram of Thompson Classifier for determining the fineness of pigments. 
 
Coarse Particles in Pigments 163 
 
 FIGURE 64 
 
 Upper photograph is of portion No. 5 separated from red 
 lead in Thompson Classifier. Lower photograph is of residue 
 in Cone No. 2. Both photographs made at a magnification 
 of 500. 
 
164 Coarse Particles in Pigments 
 
 essentially of four or more cones (brass) of graduated sizes, 
 placed one above the other, arranged so that the overflow from 
 the top cone, passing through a funnel, discharges into the bot- 
 tom of the second cone, and the overflow from the second cone 
 passes through a funnel into the bottom of the third cone, and 
 so on. The apparatus is arranged so that the liquid used can 
 work at a constant head. Jerosene is usually used as the 
 liquid. The material to be treated is diffused in kerosene so 
 that the particles are completely separated and transferred 
 into the first cone. A glass tube is then lowered into the 
 cone until it nearly touches the apex. A current of kerosene 
 under a constant. head is then caused to flow into the first 
 cone through the tube. The smaller particles are carried into 
 the next cone below, where the operation is repeated, and so 
 on to the bottom, cone. The operation requires two hours, 
 when the kerosene is allowed to settle and is decanted. The 
 sediment in each case is washed into clock glasses with kero- 
 sene, allowed to settle, decanted, and washed two or three 
 times with ether. It is then dried and weighed. 
 
 Fig. 64 shows the particles obtained in two different cones. 
 
 a 
 
CHAPTER XI 
 
 PARTICLE SIZE OF PAINT PIGMENTS 
 
 While the author has referred on page 157 to a simple 
 method he uses for the making of photomicrographs of pig- 
 ments of relatively coarse particle size, the most approved 
 method of making photomicrographs of finely divided pig- 
 ments is that developed by Henry Green.* An abstract of 
 Mr. Green’s method as prepared by him for this publication is 
 given below: 
 
 Green’s Method.—The fundamental idea involved in the 
 method is by no means a new one. In all probability it has 
 been employed many times by various investigators and for 
 numerous purposes; yet the author is not aware of a single 
 case where it has been sufficiently developed in detail so as 
 to make it of practical importance in the special line of work 
 to which it is here applied.+ 
 
 Briefly stated, the pigment is prepared in such a manner 
 so that a photomicrograph, at a known magnification, can be 
 taken, showing clearly and distinctly the individual particles, 
 which are then measured from the negative by a method to 
 be described presently. | 
 
 Preparation of Sample.—About a milligram of the pigment 
 is placed on the center of a microscope slide to which is added 
 a drop of redistilled turpentine. The slide is to be held at 
 the two ends between the thumb and first finger; a glass rod, 
 with smooth, straight sides, so that it will come in close contact 
 with the glass, is now used to disperse and rub out into an 
 extremely thin layer the material in the turpentine. This is 
 best accomplished by a forward and backward motion of the 
 rod in the direction of the length of the slide and extending 
 over the central area only. The rubbing must cease at a 
 certain critical stage, when there still remains sufficient 
 
 *“A Photomicrographic Method for the Determination of Particle Size 
 of Paint and Rubber Pigments,’ by Henry Green. J. Franklin Inst., 1921, 
 p. 638. Also “The Microscopy of Paint and Rubber Pigments.” Research 
 Bulletin, The New Jersey Zine Co., Palmerton, Pa. 
 
 +The method of grain measurement exployed by metallographers is 
 fundamentally similar to the photomicrographic method of particle meas- 
 urement. Note on grain size, by G. H. Gulliver, J. Inst. of Met., 1918. 
 
 “The Determination of Grain Size in Metals,’ by Zay Jefferies, A. H. 
 Kline, and E. B. Zimmer, Trans. Am. Inst. Mining Engineers, 1917. 
 
166 Particle Size of Pigments 
 
 PHOTOMICROGRAPHS AT 1285 DIAMETERS. 
 
 American Process Zine Oxide Show- 
 ing Characteristic Threelings. 
 
 Basic Carbonate of Lead showing 
 Basie Sulfate of Lead showing characteristic Hexagonal 
 
 tendency to erystallize in cubes. Crystals. 
 
Particle Size of Pigments 167 
 
 PereoviICROGRAPHS AT 1285 DIAMETERS. 
 
 Gas Black. Barytes. 
 
 so. 
 
 Wits 
 ui 
 ay 
 
 DS 
 
 > 
 . 
 
 * 
 
 Titanium Pigment. Silica. 
 
 * This is only 650 diameters. 
 
168 Particle Size of Pigments 
 
 turpentine unevaporated to prevent the mount becoming 
 ‘‘streaky,’’? and yet not enough to float the particles which 
 would allow them to flocculate. By a slightly upward flour- 
 ish of the rod on the last stroke the mount can be made wedge 
 shape, that is, dense in one part and thin in another, with all 
 
 PHOTOMICROGRAPHS AT 1285 DIAMETERS, 
 
 Chrome Yellow showing character. 
 istic Needles. 
 
 Prussian Blue. Red Lead. 
 
 intermediate grades of density between. In this way it be- 
 comes possible to select a section for photographing that will 
 
Particle Size of Pigments 169 
 
 show neither too many particles nor too few per given unit 
 area.” 
 
 Pe LOMICROGRAPHS AT 1285 DIAMETERS. 
 
 Raw Sienna. Ochre. 
 
 Antimouy Oxide. Zine Sulfide. 
 
 * This method of dispersing the particles is to be used principally with the 
 finest pigments, such as zine oxide, lithopone, white lead, etc. In the case 
 of these materials it will be found impossible to produce any grinding effect 
 that will cause the individual grains to be broken up into smaller ones. 
 This is on account of the fact that neither the glass slide nor the rod are 
 optically flat, and consequently they are unable to come in close contact with 
 each other except at a very few points, 
 
 With coarser materials such as clays, bartyes, asbestine, ete. (which will 
 probably feel gritty), only the slightest possible pressure must be brought 
 to bear upon them with the dispersing rod, for here there ‘is some danger 
 of a real grinding effect becoming manifest. Fortunately, these materials 
 are so large that flocculation does not prevent the outline of the particles 
 from being seen and a measurement made, hence, very little rubbing is 
 necessary. 
 
170 Particle Size of Pigments 
 
 The next step, after the material is properly dispersed, is to 
 completely remove the remaining turpentine. This should 
 be done by laying the slide on a hot plate, the temperature 
 of which is sufficiently high to cause evaporation within forty 
 or fifty seconds. Care must be taken that volatilization is 
 complete. This is satisfactorily ascertained by noticing if 
 any odor of turpentine remains after heating. The particles 
 will now be found to be cemented to the glass and should 
 remain in this condition, if a reasonable amount of eare is 
 exercised in handling the slide. When sufficiently cooled a 
 small drop of glycerine is placed on the center of the mount 
 and then covered with a thin slip. The exeess glycerine must 
 be carefully squeezed out at the sides of the cover glass and 
 absorbed by filter paper. The mount is finished in the usual 
 manner with a ring of Brunswick black. 
 
 If the above instructions have been properly carried out, 
 and the mount now held to the light, the pigment, if its index 
 of refraction is high, will just be perceptible as a faint cloud; 
 if its refractive index is low, the pigment will be entirely in- 
 visible, except with a microscope. 
 
 Upon microscopic observation three essential conditions 
 should be manifest. They are— 
 
 1. The particles will be in one plane. 
 
 2. They will be free from Brownian motion. 
 
 3. ‘They will be dispersed, showing individual grains in- 
 stead of aggregates and flocculates. 
 
 Photography.—lIt is not the purpose of the present paper to 
 describe the method of using a photomicrographie apparatus. 
 It is also hardly necessary to add that unless one has acquired 
 considerable facility in the manipulation of such apparatus 
 it would not pay to attempt its application in the measure- 
 ment of particle size. 
 
 In regard to the present problem, however, it must be stated 
 that all photographs are made with transmitted hight, and 
 that this light is to be absolutely axial. Obliquity of illumi- 
 nation will give a distorted image, causing an appreciable 
 error in the results. 
 
 The beginner will find it advantageous to start with a fine- 
 grained contrast plate, using hydroquinone developer. After 
 he has obtained experience in handling these materials suc- 
 
 ae ee ee 
 
Particle Size of Pigments 171 
 
 cessfully, he should then try his ability with panchromatic 
 plates and develop with pyro. There are plates of this kin“ 
 made especially for photomicroscopy which give great detail 
 together with sufficient contrast. 
 
 Magnification—Generally, in photomicrographie work, 
 definition of structure is the one essential quality most de- 
 sired. However, as the structure of a pigment particle will 
 give us no information in regard to its size, the factor, defi- 
 nition, may be neglected here to a certain limited extent.* 
 On account of this fact it has been found an advantage to 
 employ a magnification which otherwise would be too high 
 if the best definition is to be obtained. Nevertheless, care 
 must be taken that the photographic image of the particle 
 gives edges sharply enough defined so as to make a satis- 
 factory measurement possible. 
 
 With a 2 mm. apochromatic objective a magnification of 
 1,500 diameters will be most convenient for pigments such 
 as zine oxide, lithopone, red oxide of iron, sublimed white 
 lead, corroded white lead, Mathewson white lead, ete. Lower 
 magnifications are used, naturally, with coarser materials. 
 
 Measurement.—As previously pointed out, it sometimes 
 becomes necessary to measure a thousand or more particles 
 in order to obtain a sufficiently accurate average diameter. 
 This demands a rapid method of measurement, if the work 
 is not to become too irksome. The method is as follows: 
 The negative, which must show from 200 to 250 distinct parti- 
 cles, is placed in a stereopticon and an image of it thrown on 
 a screen, so situated that the total magnification of the origi- 
 nal particle will be from 20,000 to 25,000 diameters. The 
 image of the particle is measured with a millimetre rule. 
 Particles which are out of focus to any extent at all, as the 
 case will be with those around the border of the negative, 
 must be neglected. In order to eliminate the possibility of 
 duplication and skipping, the area of the screen is divided 
 into small squares. 
 
 It is neither necessary nor desirable to consume time in 
 
 estimating the fractional part of millimetres. These small 
 errors are just as liable to be positive as negative, and it is 
 
 * But to no greater extent than is shown in the photomicrographs. 
 
172 Particle Size of Pigments 
 ee a a 
 reasonable to believe that their sum approaches zero as the 
 number of measurements increases. 
 
 The length of time required for the measurement should be 
 approximately two seconds. As the readings are called off 
 an assistant takes them down. The results are plotted as 
 particle diameter, d, against particle frequency, n.. This gives 
 the so-called particle distribution curve. 
 
 The particle of average size is a hypothetical particle that 
 in some particular way represents the total mass of particles. 
 Just what feature of the total mass of particles is to be repre- 
 sented will depend upon the nature of the problem to be solved. 
 One thing is apparent, however, and that is that one average 
 particle size cannot serve for all possible purposes. The most 
 useful average diameters expressed as functions of d and n 
 are: | 
 
 Arithmetical mean = Snd/Sn 
 The diameter of the particle of average surface = VSnd?/Sn 
 
 The diameter of the particle of average volume (the 
 diameter determined with the slit ultramicro- 
 
 scope) = ¥/3nd3/Sn 
 The diameter from which specific surface is 
 determined = Ynd3/rnd? 
 
 SY 
 
 Particle Size and Distribution by Sedimentation Method 
 (Abstract)—A special balance pan is suspended in a pigment- 
 vehicle mixture and the weight of pigment settling on the 
 pan is noted at successive intervals of time. If the falling 
 particles are spherical, the radius may be computed from 
 Stoke’s law of falling particles. 
 
 ee nh 
 ro 2) (dessdaeniner 
 
 where r = radius 
 n= viscosity of medium 
 h = distance in em. 
 d'= sp. gr. of particles 
 d* = sp. gr. of medium 
 2 = gravity, cm/sec’. 
 
 t = time, minutes. 
 
 * J. H. Calbeck and H. R. Harnes, J. Ind. Eng. Chem. 19, 58—1927. 
 
Particle Size of Pigments eS 
 
 — SS SS SSS SS 
 
 Since pigment particles vary considerably in shape, the 
 radii are those of a perfect sphere of the same material that 
 sinks through the fluid at the same average rate as the par- 
 ticle in question. Data on several samples of red lead and of 
 one sample of litharge are presented in the original article. 
 
 Relative Method for Determining Particle Size of Pig- 
 ments.* (Abstract).—The authors measured the relative aver- 
 age particle size of a pigment by determining the amount of 
 hight transmitted by a suspension of the pigment. The amount 
 of light transmitted by a suspension is inversely proportional 
 to the amount of reflection from, the total surface of the pig- 
 ment. Hence, the more finely divided the pigment, the greater 
 the surface and the less the transmission. This relation holds 
 true, however, only until the particle size becomes so small 
 that it behaves as a source of light and scatters some of the 
 light. This scattering out being directly proportional to the 
 sixth power of the diameter of the particle, decreases rapidly 
 with decrease in particle size. Hence, the transmission below 
 the critical size increases rapidly and the hiding power of a 
 pigment passes through a maximum as the particle size is de- 
 creased. With this method a pigment must first be rated as 
 to average size of particles by an independent method, but 
 after such data is once obtained subsequent measurements 
 of hiding power may be compared with that data. Since the 
 refractive index of the pigment also is a factor in the opacit~ 
 of a suspension, separate data must be obtained for each kind 
 of pigment. 
 
 Relation of Yield Value to Particle Size.+ (Abstract).—The 
 pigment particles in a paint are visualized as groups of loose 
 clusters of pigment particles easily dispersed by stirring and 
 easily reformed as motion ceases. The flocculation is prob- 
 ably due to interfacial tension. The force necessary to over- 
 come this tension is probably the yield value. Since the 
 interfacial tension depends upon the interfacial area (I. F. 
 A.) of the particles and the number of points of contact (P. 
 C.), the yield value involves these variables. Particle sizes 
 of zine oxide were determined by photomicrographic methods. 
 The yield values were measured by means of the Green and 
 Haslam microplastometer. Determinations of yield value 
 were made first by keeping the I. F. A. constant and varying 
 the P. C.; and by keeping the P. C. constant and varying the 
 I. F. A. The results are given in tables and charts in the 
 original article. 
 
 *G. F. A. Stutz and A. H. Pfund, J. Ind. Eng. Chem., 19, 51—1927. 
 ¥ Henry Green and G. S. Haslam, J. Ind. Eng. Chem., 19, 53—1927. 
 
CHAPTER XII 
 
 SURFACE TENSION AND INTERFACIAL TENSION OF VARNISHES 
 AND PAINT LIQUIDS 
 
 While viscosity probably exerts a predominant influence on 
 the working and spreading characteristics of a varnish or 
 paint liquid, the appearance of the film after application will 
 also depend to a certain extent upon the surface tension rela- 
 tions existing between the liquid film and the solid underface. 
 Phenomena such ag the tendency of oils to draw together in 
 drops, the ease of wetting and grinding of various pigments 
 with different oils, etc., have been conceived of as surface ten- 
 sion effects. The pitting of varnishes and baking japans or 
 paints may also be at least partly due to this cause. 
 
 Surface tension as usually discussed refers to a tension or 
 strain at the surface of a liquid in contact with air which 
 causes the surface to act as though it were an elastic mem- 
 brane. In a mass of liquid each molecule exerts an attractive 
 force upon other molecules within a definite radius. As each 
 molecule within the mass of the liquid is surrounded by other 
 molecules, the attractive forces exerted upon it by surround- 
 ing molecules is equal in all directions. The molecules im- 
 mediately upon the surface, however, are exposed to mole- 
 cular attraction only from the interior of the mass of liquid 
 and there is consequently a molecular pull toward the interior 
 of the liquid. The inward molecular pull results in a tendency 
 to contract, drawing the surface molecules inward. 
 
 While the measurement of this contractile tension at the air- 
 liquid surface is of great theoretical interest and has numer- 
 ous important applications (as, for example, the determina- 
 tion of molecular weights, structure of compounds, arrange- 
 ment of molecules in the mass, ete.) it has so far been of little 
 assistance in solving the problems confronting the paint and 
 varnish chemist. It does not serve to distinguish between 
 liquids of the same class or to explain phenomena frequently 
 observed. Difference in the density of the phases on opposite 
 sides of the surface are so large as to obscure small differences 
 in the tension of different liquids. Conditions existing at 
 liquid-solid or liquid-liquid surfaces, are, however, of great 
 importance in the present connection. At such a surface 
 
Surface Tension—Interfacial Tension 1B) 
 
 where the density on each side is approximately the same, 
 differences in the intensity of the tension of different hquids 
 against another immiscible liquid or a solid may be detected, 
 since here the combined effects of both liquids are measured. 
 The tension existing at other than air-liquid surfaces is usu- 
 ally distinguished as interfacial tension and will be go desig- 
 nated in this chapter 
 
 In varnishes (colloidal solutions) and paints (suspensions) 
 where the surfaces between solid and liquid are extraordi- 
 narily great, the magnitude of the interfacial tension between 
 
 the phases becomes a very important factor in determining 
 the characteristic of the liquid. 
 
 There are, therefore, several kinds of surfaces to consider 
 and it is desirable to ascertain whether there is any relation 
 existing between the tensions at these surfaces in different 
 liquids, and the characteristics of the hquid film. From a 
 practical point of view, the most important of these various 
 tensions is that at a liquid-solid surface. Very little is known 
 concerning this tension, and it appears at present impossible 
 to measure it. Relative values for the interfacial tension be- 
 tween immiscible liquids can be easily obtained. The abso- 
 lute methods of precision which are at present available, how- 
 ever, apply to only one of the tensions—namely, that in the 
 surface of the liquid against air, or its own vapor. 
 
 Air-Liquid Tension.—Three methods are commonly used for 
 measuring the contractile tendency existing at the surface 
 of a liquid in contact with air. 
 
 Capillary Tube Method—Surface tension is measured by 
 the height to which the liquid will rise in a capillary tube of 
 known diameter. The liquid rises until the tendency of the 
 film to contract is balanced by the weight of the column of 
 liquid. 
 
 Drop Weight Method.—Surface tension is measured by the 
 weight of a drop forming at an orifice of known diameter. The 
 weight of the drop increases until it overcomes the surface ten- 
 sion of the liquid. 
 
 Air Bubble Method. Surface tension is measured by the 
 size of an air bubble forced through the liquid, the size being 
 proportional to the surface tension of the liquid. 
 
176 Surface Tension—Intertacial Tension 
 
 These methods yield accurate results but require consider- 
 able time and manipulative skill. The apparatus illustrated 
 and described: herein is easily and quickly operated and yields 
 results that check fairly close with the above methods. It was 
 used for obtaining the figures given in Table 31. 
 
 As indicated in Table 31, surface tensions of liquids of dif- 
 ferent types, such as oils and volatile thinners, vary somewhat, 
 but in different liquids of the same type the difference is too 
 ~ small to explain great differences in behavior. It also appears 
 that liquids of different types may show the same surface ten- 
 sion when they would be expected to have widely varying 
 values. The measurement of surface tension, is, therefore, of 
 
 FIGURE 65 
 
 This apparatus, designed by Dr. P. L. DuNouy of the Rockefeller Medical 
 Institute, is manufactured by Central Scientific Company, Chicago, Ill. For 
 a description of the instrument and details of operation see Bulletin No. 82, 
 Central Scientific Company, and the Journal of General Physiology, May 20, 
 1910, Vol. 1, No. 5. 
 
 ae a 
 
Surface Tension—Interfacial Tension es, 
 
 little assistance in studying the physical peculiarities and 
 variations in properties so frequently encountered in paints 
 and oils. 
 
 TABLE 31.—Measurement of Surface Tension Against Air by DuNouy 
 
 Apparatus. 
 Oils— Dynes per cm, 
 ng vial eoiin macaw acdue 6 ¥ 6 See elas Genel elena's 38.5 
 emermeiie yo a(. FOLY 10 MiNS: ...s. sina cs wee et ee ee eae 38.5 
 ee ee TOY 2) WINS <. . . sv k oe sce wd ew ea ciceevas oo 
 Serie eet POT S30) TAINS kok ce Sc ce wv eae c eae 38.5 
 rrr maa roe TOT GO MINS. oc etee «oo ste ece cnccees 39.0 
 eee Ome 4 = TOP Or IMINS ss osc cu ccs ee ee ele te eee 39.0 
 EU BED 2 ae a ee a oid 
 I iy sg vlads anda bmpuveenteiebuea vee 39.0 
 Thinners— 
 Ee Shaka sh cee «ke bet «pine csc pleas copeues 31.5 
 MRTPEEILCTILOIUCTIZOL (6)... o 05.5 ce te ee st ees A a eer Me 40.5 
 Mineral Spirits— 
 <8 RRS oa ae Oy ese ER Sie RS Era ae a ag eR 29.0 
 a oiay sds Se aad acd shes b ele sic s et yee cee ep aie 29.0 
 ee 5 alg gslcice 55 Mie aS le oye 0, sles wid eco m cele ‘enn 29.5 
 ERB ayaa cao wk sin ve s ociw sis ae sols cle wes es owe 29.5 
 ee fae e lola k chdn o «bee @ew'aw eh ap ae wees 30.0 
 a e Sra sb a sh's i's owe wietels s 90.5. ¥ aus ee oe 0 tlee 30.5 
 so LS cl a's ss: abso pe wiets.e% vba cd ae ee ee eee 31.0 
 a EE a ics cc ok wie ee ase 6 oe # ale gs be mela Sean Slee 
 
 Since no way of measuring the tension at a liquid-solid sur- 
 face is known, it is desirable that means be found for deter- 
 mining values which will explain differences observed in 
 different liquids. 
 
 Wells and Southcombe* have observed a definite relation 
 between the interfacial (oil-water) tension of lubricating oils 
 and their power to wet metallic surfaces. They find that the 
 lower this constant is, the greater will be the wetting power or 
 ‘‘oiliness’’ of the oil. The ability of various oils to wet a given 
 pigment is probably governed by the same relation. If the ten- 
 sion is low the oil should spread easily and be readily made to 
 cover every facet of the pigment particles. 
 
 Interfacial Tension.—Relative values for the interfacial ten- 
 sion between liquids were obtained by the use of the apparatus 
 shown at B in Fig 66. This apparatus as prepared by the 
 writer consists of a 5 ec. pipette bent upward at the lower end 
 and drawn to a point having an orifice of about .8 mm. It is 
 supplied with a rubber tube and clamp to facilitate filling and 
 to regulate the influx of air during the determination. The 
 
 * Soc. Chem. Ind., pp. 51-60 T. (1920). 
 
178 Surface Tension—Interfacial Tension 
 
 volume between upper and lower marks equal about 4 ce. The 
 figures given in Table 32 were obtained with this instrument: 
 The pipette is filled to the mark and maintained at this level 
 by closing the clamp. The lower end is immersed in a beaker 
 containing water or some other immiscible liquid at the de- 
 sired temperature. Enough air is admitted by loosening the 
 clamp to cause a slow efflux of oil in a series of distinet drops 
 from the capillary tip. As the drops break loose and rise to 
 the surface one at a time they are counted. From 5 to 10 
 minutes are required for a determination. 
 
 FIGURE 66 
 
 The instrument shown at A has been designed by the writers 
 to secure greater convenience in operation and greater ac- 
 curacy, and will be used in future work. The size of the capil- 
 lary to be used will depend upon the viscosity of the liquids 
 tested. It may be advisable to have two instruments fitted 
 
 ai 
 
Surface Tension—Interfacial Tension 179 
 DTT ee 
 with differ ent-sized capillaries to take care of extremes of 
 viscosity.” 
 
 If a capillary tube as shown at A is used it is eects that, 
 in each determination the top of the tube be perfectly clean 
 and free from the liquid the interfacial tension of which is to 
 be measured. If it is not kept clean the liquid in emerging will 
 spread over the top of the tube, producing drops of non-uni- 
 form size and render the determination worthless. 
 
 The number of drops formed by a definite volume of liquid 1s 
 inversely proportional to the interfacial tension. In compar- 
 ing two liquids specific gravity must be taken into considera- 
 tion. The number is also influenced by both temperature and 
 the depth of immersion of the capillary tip. Since observa- 
 tions are made at or near room temperature, it will be suffi- 
 cient to maintain the water at the desired point, as the liquid 
 in passing through the submerged part of the tube to the capil- 
 lary tip will come to the temperature of the water. If the 
 beaker is always filled to the same height and the instrument 
 rests on the bottom the degree of immersion will, of course, be 
 the same. While the results thus obtained are only relative, 
 the values for different liquids of the same class vary greatly 
 and the differences are such as might be expected from their 
 properties. 
 
 In Table 32 a difference in drying oils and thinning liquids 
 not shown by the usual surface tension methods is indicated. 
 For instance, perilla and chia oils are seen to have a much 
 higher interfacial tension against water than has linseed oil. 
 If the same relation holds at solid-liquid surfaces (which ex- 
 ists in applying the oil to a solid surface) it appears that this 
 higher interfacial tension would account for the ‘‘crawling’’ 
 of these oils. The low value found for extracted linseed indi- 
 eates that the interfacial tension was reduced by the large 
 percentage of free acid. Accordingly it was found that when 
 different percentages of linseed oil acids were added to a lin- 
 seed oil of low acid value, the interfacial tension was greatly 
 decreased. 
 
 The addition of linseed oil to perilla oil lowers the inter- 
 facial tension of the latter against water. In the mixture of 
 
 * This Laboratory has turned its design over to the A. H. Thomas Com- 
 pany of Philadelphia. This firm has satisfactorily produced the apparatus 
 In accordance with the design for $6.80. 
 
180 Surface Tension—I nterfacial Tension 
 
 oils given the crawling effect was found to be entirely over- 
 come. While heating for a few minutes at a high temperature 
 appears to lower the interfacial tension, if the heat is con- 
 tinued longer the tension again increases. The increase in 
 viscosity, due to prolonged heating, apparently overcomes the 
 surface tension effects in the case of perilla oil. 
 
 TABLE 32—Measurement of the Tension at the Liquid-Liquid Surface 
 Against Water 
 All Measurements made at 20° C. 
 
 Number 
 Liquids of drops 
 Raw Linseed 2.00004. eee ses eeuscus euls oes spelen 55 
 Linseed extract (acid value 22) ...........). 00 ee 82 
 95% Linseed 70 
 5% Linseed acids CoC CCC ORO eee eee Ome e RO oe eb 6 6 0s 66 ols hie os) Sate 
 90% Linseed dss ssesuscese ear 90 
 10% Linseed acids { . 
 80% Linseed 295 
 20% Linseed acids eoeeetmweoeeseoe veep eBeoeeseee ss © 0 ¢ 06 2 6 8 6 6 6 8 8 8e 2 ee 
 Perilla wc ccc ccs eeccevesaveuaneusnveasea eed shel neta = =a 37 
 Chia. . cee ienetas Ga eueueeec ceases a anh eine e naz 32 
 Perilla (heated at 280° GC. for 10 minutes). ... <u .eeeee 42 
 Perilla heated 20 minutes at 230° C.......... «sie elenaieia ee 33 
 Perilla (heated at 260° for 2 hours) .......... os eee 30 
 Alkali ‘refined. Linseed “oil, cca. 2.2 ee POOR ee ee 44 
 Acid refined Linseed oil... ........000+«s c+ we pe get 44 
 Linseed fatty acids... 22. 5.05. 0.00 ca vo «ole ene eee ene 300 
 66 2-3% Linseed 52 
 3813% Perilla (°7771 ttt terete rest eet nneees se seueueae 
 Varnish makers’ Linseed oil heated at 500° for 2 hours.............. 36 
 Perilla heated to 300° C. rapidly.....2..,..0..s0ee eee 35 
 Cold pressed Lumbang... 3.000. cc0s 5 «ee «ok ee pi eee 41 
 AA oil (causes pitting of japans)..... ‘ele alle oe sine 5 gle a eta atten 33 
 Varnish 2. ees c ccc ndw ey women ww a ecne sila ao ea 40 
 Turpentine ...... 5 cee ees csecee nw oe cle oe 5 area ae nt nae 115 
 Mineral spirits... .....0<600000 01+ us og ule ogee 79 
 Against Salt Solution 
 TUIpentine 22.660 cece de ecw ee neces soe se 5 0\ 8 alee nthe 135 
 Mineral spirits. ...06...c00 0. bcos eeu eels s'est ce alten 89 
 
 Turpentine and mineral spirits which show the same surface 
 tension exhibit a very different interfacial tension against 
 water. This result indicates that the selection of suitable thin- 
 ners for various types of paint and varnish liquids is a matter 
 of great importance. 
 
 All solid surfaces are believed to hold an adsorbed film of 
 moisture. Although this film may only be of molecular thick- 
 
 ness, it may yet form a continuous layer between the solid sur- 
 face and the applied coat. If such is the case it is conceivable 
 that the surface is really liquid-liquid instead of liquid-solid, 
 and that the conditions obtaining in the measurement of the 
 
Surface Tension—Interfacial Tension 181 
 
 interfacial tension against water as described herein closely 
 approximate actual working conditions. If this tension is in 
 any way related or proportional to the tension which actually 
 exists at a solid-liquid surface it should hold for all immiscible 
 liquids. If a definite relation holds for the liquid to be tested 
 against any immiscible liquid it could more justifiably be used 
 as indicating solid-liquid tensions. When determinations 
 were made using salt solutions the ratio between the number 
 of drops of turpentine to mineral spirits was approximately 
 the same as when pure water was used. 
 
 An explanation for the existence of equal surface tensions in 
 liquids of the same kind is advanced by I. Langmuir, who re- 
 fers it to the arrangement of molecules in the surface layer. 
 He states that: 
 
 The group molecules of organic liquids arrange them- 
 selves in such a way that their active portions are 
 drawn inward, leaving the least active portions to form 
 the surface layer, the active portion of the molecule be- 
 ing that part of the field characterized by a strong stray 
 field (residual valence). Surface energy is thus a meas- 
 ure of the stray field which extends out from the sur- 
 face layer of atoms. The molecules in the surface layer 
 arrange themselves so that this stray field is a mini- © 
 mum. 
 
 The surface energy of a liquid is thus not a property 
 of the group molecules, but depends only on the least 
 active portions of the molecules and on the manner in 
 which they are able to arrange themselves in the sur- 
 face layer. In liquid hydrocarbons of the paraffin 
 series, the molecules arrange themselves so that the 
 methyl groups (CHs) at the ends of the hydrocarbon 
 chains form the surface layer. The surface layer is 
 thus the same, no matter how long the hydrocarbon 
 chain may be. As a matter of fact all these many 
 different substances from hexane to molten paraffin 
 have substantially the same surface energy, namely 
 46 to 48 ergs per square centimeter, although the mole- 
 cular weights differ greatly. 
 
 If now we consider the alcohols such as CH;OH, 
 C2H,OH, ete., we find that their surface energies are 
 practically identical with those of the hydrocarbons. 
 The reason for this is that the surface layer in both 
 cases consists of CH; groups. 
 
182 Surface Tension—Interfacial Tension 
 eet 
 Accepting the above statement as true, the measurement of 
 the surface tension of liquids against air would yield im- 
 portant information in regard to substances of different molec- 
 ular groupings. It will not, however, serve to differentiate 
 in any way between liquids which have the same atoms or 
 groups in the surface layer. While it is possible that the so- 
 called active portions of molecules may be drawn inward at 
 any surface, whether air-liquid, liquid-liquid, or liquid-solid, 
 it is probable as already pointed out, that the tension in the 
 latter cases has a very different value from the former. Differ- 
 ent vegetable oils may therefore show the same tension against 
 air due to the fact that they all present the same group or por- 
 tion of the molecule at the air surface, but it is conceivable that 
 in contact with another liquid or a solid (pigment) different 
 oils may have different groups in the surface layers, particu- 
 larly if the active groups possess an affinity for the surfaces 
 with which they are in contact. We have, therefore, different 
 manifestations of the same force depending upon whether we 
 are considering the tension between the liquid surface and air 
 or the tension between the hauid and another liquid or a solid. 
 
 Technical Paper No. 540 of the U. S. Bureau of Standards contains 110 
 references on the subject of Surface Tension. 
 
CHAPTER XIII. 
 
 ULTRAVIOLET LIGHT STUDIES ON PAINT PIGMENTS AND 
 LIQUIDS 
 
 Considerable work has been done by P. R. Croll and J. D. 
 Jenkins, on the relative transparent nature of films to utlra- 
 violet rays. The writer submitted to them early in 1924 a 
 sample of a special glass that had been ground to a pigment, 
 with the request that determination be made of its opaqueness 
 to ultraviolet rays. Their photographs were made through a 
 thin layer of metallic silver which is transparent only in a 
 narrow band of the ultraviolet, around 3100A’s. Subsequently 
 they received a Corning filter quite opaque to visible rays but 
 very transparent to the ultraviolet down to about 3000 A’s. 
 
 Fy 
 Hy 
 a 
 H 
 nititinnesstananaptonie 
 povecevnnnon em eee Mee 
 
 H 
 | 
 i 
 
 FIGURE 67 
 
 Diagram showing method of photographing pigments by reflected ultra- 
 violet light. (Croll.) 
 
 In their subsequent work on the glass pigment forwarded to 
 them, they used as a light source an iron are with 5 amperes 
 and 40 volts. Exposure was made in back of a screen, at a 
 
184 Ultraviolet Light Studies 
 
 distance of about fifteen inches from the are, the screen being 
 interposed between the are and the paper. The pigments 
 were illuminated by the light from the iron are, the light pass- 
 ing through the screen. They were then photographed by 
 means of a pin-hole camera from above. A sketch of the ap- 
 paratus used, together with the results obtained with zine 
 oxide, the special powdered glass, silica, and white lead, are 
 shown below. As was expected, the zine oxide appeared black 
 in ultraviolet light, because such light is absorbed by this pig- 
 ment. The pigments that did not absorb the ultraviolet light 
 appeared white. 
 
 FIGURE 68 
 Photographs of pigments taken by reflected ultraviolet light. (Croll.) 
 Transparency of Pigments to Ultraviolet Radiation.—Inter- 
 
 esting work has been done on this subject by A. H. Pfund and 
 Rk. L. Hallett. The most recent work, however, and probably 
 the most elaborate was presented by G. F. A. Stutz in an 
 
 article entitled ‘‘The Testing of Paint Pigments for Trans- 
 parency to Ultra-Violet Radiation,’’ published in the Journal 
 
 ie met oy 
 
Ultraviolet Light Studies 185 
 
 of the Franklin Institute, July, 1926. <A description of the 
 apparatus and method, as well as some of the results are re- 
 printed below. 
 
 H. A. Nelson, Proc. Am. Soc. Test. Mat., 22, Part II, p. 485 (1922). 
 A. H. Pfund, Proc. Am. Soc. Test. Mat., 23. Part II, p. 369 (1923). 
 G. F. A. Stutz, Jour. Frank. Inst., July, 1925, p. 87. 
 
 R. L. Hallett, Proc. Am. Soc. Test. Mat., 23, Part II, p. 379 (19238). 
 
 Stutz Apparatus and Method.—‘‘In this work, the apparatus 
 has been modified as suggested by Doctor Pfund, so that both 
 the reflected and the transmitted light are caught in diffusely 
 
 Fhotograplic 
 ws Prare 
 
 / Quarrz 
 l Spectrograph, 
 a 
 
 /lntegrating Sphere for 
 wreflected Light. 
 
 Integrating Sphere 
 lfercury Vapor Lamp. 
 
 for Transmitted 
 Light 
 
 Fro tating 
 Secror. 
 
 FIGURE 69 
 
 reflecting spheres. The arrangement is shown in Fig. 69. Light 
 from the quartz-mercury lamp is rendered parallel by the 
 
186 Ultraviolet Light Studies 
 (nh 
 quartz lens L, and impignes on the paint film contained in the 
 quartz cell. The total transmitted light is caught by the mag- 
 nesium-oxide-coated sphere and enters the quartz spectrograph 
 as shown. The light reflected by the film is collected in a simi- 
 lar sphere. The whole apparatus is mounted on a slide, so that 
 it ean be moved to the left until the light from the second 
 sphere enters the spectrograph. 
 
 ‘(The amount of light reflected and transmitted in each case 
 was measured by the darkening produced on the photographic 
 plate. The rotating sector was used to give a series of com- 
 parison spectra of known amount, transmission being made 
 through a cell containing the clear vehicle, and reflection be- 
 ing made from a surface of magnesium carbonate. 
 
 ‘“The cell used consisted of two quartz plates with a bronze 
 separator, .09 mm. thick. The pigments were incorporated in 
 castor oil, since this has practically no absorption in the wave- 
 length interval from 4400 to 2900 AU. The spectrum in each 
 ease is that of the light of the quartz-mercury are after pass- 
 ing through a vehicle film .09 mm. thick. For more complete 
 
 data on the absorption of ultra-violet light by vehicles the 
 
 reader is referred to a previous paper. 
 
 ‘A weight of pigment equal to .053 ¢.c. (calculated from the 
 density) was incorporated in 5 ¢.c. of castor oil. This is an 
 approximate volume ratio of 1 per cent pigment, 99 per cent 
 vehicle. When this mixture was placed in a cell .09 mm. thick, 
 the amount of pigment in the cell was sufficient to form a layer 
 00092 mm. thick. The thickness of the pigment layer was 
 varied in some cases by the addition of a greater or less vol- 
 ume of pigment. 
 
 Results—‘‘Since the reflection factors parallel those of 
 Pfund and the writer, the transmission measurements only will 
 be presented. 
 
 Table 33 gives the results for the white pigments, inerts 
 and blacks, and Table 34, the results for the colors. The last 
 column in each table gives the thickness at which the pigment 
 is opaque to light of 3655 A.U.”’ 
 
 Ultraviolet Effects Upon Paint Liquids.—The apparatus and 
 method developed by Stutz for determining the effect of ultra- 
 violet ight upon paint vehicles and originally presented in 
 the December, 1926, issue of Industrial and Engineering Chem- 
 
Ultraviolet Light Studies 187 
 
 TABLE 33 
 White Pigment—Inerts—Blacks 
 
 Per Cent. Transmission of Pigment | Thickness 
 
 .00092 mm. Thick at at Which 
 Pigment Wave-length Pigment 
 Is Opaque 
 to 3655 
 4358 | 4047 | 3655 | 3342 | 3131 | 3023 | 1 mm. 
 Antimony oxide pigment.................. 48 | 47 -| 39 | 24 10 0 .0065 
 Hacic lead carbonate.......................... O0tmer 00s fOr 7.0.) o0e. 1 oF .0270 
 Basic lead sulphate........................00. [ime COsee Oe tao boo tos .0052 
 OS a ee SOm desea dea ryt oe 15 5 .0100 
 Extra-strength lithopone.................. ya a ee a 20 f 8 .0085 
 
 Pigment composite (40 per cent. 
 lithopone, 40 per cent. zinc oxide, 
 
 OO A Cad SOs 43°54 12 7 6 6 .0020 
 PPGer Pte PMEIMENE) oo. 2.. <2. .ses. eee. ese O39 18 iS 12 11.5} ..0046 
 100 per cent. titanium dioxide..........) 35 32 18 6 co: ha .0031 
 Zinc oxide (American process).......... 44 | 38 0 0 0 0 .0009 
 Zinc oxide (French process).............. 46 | 40 0 0 0 0 .0009 
 Zinc oxide (35 per cent. leaded)...... 50 | 45 9 8.5] 8 8 .0015 
 0S Te Se Serie 2h 1S 0 0 .0062 
 LL a 90° 1-90 )<90 «1789 | 88 si and pea Cees? 
 i ee as 68. |) 67 65 64,5647 4) 05/51 aie 
 oA G39)-61 BOS st 5 Sir) OAS Ee ae 
 Gloss white (BaSO, + Al (OH);)..... 79 | 80.5/ 79.5| 78 | 76 | 75 |... 
 (Eo ad a a BP reGse Cae O82 “1h esc 7 Onin oe 
 ccc. oenccyiseennnsccevnesseecennss- 88 88 85 82 80 (ita Mtoe a 
 Ce ik SC Se 74.5| 76 (6 rece ied ie) 78 POl5 eee ae ce 
 Rg, cay asses cceacsessepdeereseeess 71 69 68 67 66 OS lie Seat 
 a er 0 0 0 0 0 .0006 
 ee ee HG ced Pala Be 17 15 13 1h .0030 
 ee .......| 26 | 24,5| 23 | 205) 19 | 18 | ........ 
 yee.) 1.5) 1 eine aed i 1 .0015 
 DRAG ic, (onncecaeveencs-ceeeoeecessssee 7 7 2G. eo 6 
 Magnetic iron oxide (98 per cent.)....| 12 13 14 14 15 15 .0017 
 
 istry, have been used to advantage in such studies. <A brief 
 abstract of this method is given below: 
 
 Method.—The effect of ultraviolet light on a mass of wet 
 oil has been studied by placing about 300 ec. of oil in a 400-ce. 
 flask of clear fused quartz, and exposing it to a Cooper-Hewitt 
 quartz Uviare at a distance of 30 em. (12 inches). The oil was 
 stirred continuously with a small glass stirrer, and a slow 
 stream of air, oxygen, or nitrogen bubbled into the oil. The 
 temperature stayed nearly constant, at about 50° C. The oil 
 was sampled at intervals until it had attained a considerable 
 body. The viscosity of the several samples was determined 
 by use of the Gardner-Holt tubes and, in the case of the 
 samples beyond the range of the tubes, the result was obtained 
 
188 Ultraviolet Light Studies 
 
 TABLE 34 
 
 Colored Pigments 
 
 Per cent. Transmission of Pigment | Thickness 
 .00092 mm. Thick 
 
 Pigment 
 
 4358 | 4047 | 3655 
 Adwumantiny vst ee oe ee 47 46 45 
 Bivetoer Ay, it wee es eee 50 47 22 
 Chinese Dives. je) 00 ieee arte eee ee 48 39 28 
 Iron lite. Ssh. cao a ete ee 70 63 57 
 Ponsol bine ee a ee ee 75 53 49 
 Prussian bide hey aan eee 58 36 31 
 RIVISTA DINE. O eo ee ee 90 89 87.5 
 Sublimed blue lead........0..ccccccccenes 9 9 8 
 ‘Dordtmise-blue..22 3 oo ee ee 93 1.88 71.5 
 Ultva-maring blue: .3..2. sa ees 88 88 85 
 Chrome ereencnf i ee, ee 2 aioe 
 CP, SECC ee eae ee 7 ¥ De 
 Cy. P; green miedittiy 302 ae eee 5 6 5 
 C.-Po green darks oe te eee fi ‘é Ls 
 Pine. @reén jo sn ee 5 3. 
 Chromium oxide: 22 ene 19 12 10 
 Madder lake.vn cursus So eee Aas 1557-28 20 
 American ochre. 7. i..0. a wae eee on 29 Ri 
 Ochre: Anis eee 40 31 26 
 Orange mineral osoio) Gs ie ae 65 63 55 
 Para toner is. co to eee 8.5.0 8.5 
 light para toners > 302) se eee De 49 s1S 
 Alpha naphthylamine......0.000.0........... 645.) 632 ST 
 Pigment-scarlet tomer: <o... > ae 70 67 62 
 Pigment scarlet on gloss white........ 95 91 82 
 Red leads). tro A ae es ae ee 67 67 65 
 wearlet lead chromate... 25. 65 60 3 
 Mercurie sulphate s.4). ee 72 71.5] 69 
 Iron:oxide #3) Va.7 ae ee 50 52 52.5 
 Irom omde! (03. tis eee 15 18 19.5 
 Iron oxide 909, ie ee ene 2,54 VS eas 
 Tron. oxide: O80 2 Ge. age 0 0 iS 
 Metallic brown, 50% iron oxide...... 45 44 42 
 Rawesienig. See HL 24 ri 
 Dirtat sientigic yeu ee 1 5 » 
 Cadmium Lithopone....i,...05 004 4.. 17 17 16 
 Zine chrome es 0c ee een 35 33 32 
 Chrome yellowiin: 7 ee 11 13 14 
 Medium yellow. vi ae ee ce 3 4.5| 6 
 Rawoumber kone. eee ae 29 26 24 
 Burat- inert cht anaes 8 8 8 
 Zinc dust (blue powder).................. G35 4] sou 50 
 
 3342 
 
 at Wave-length ~ 
 
 3131 | 3023 
 41 | 40 
 0 0 
 16 14 
 40 | 36 
 O27 ees 
 10 4.5 
 82 80.5 
 0 0 
 68.5| 68 
 77 75 
 0 0 
 2 1 
 1 0 
 2 i 
 6 6.5 
 105-11 
 Zz 0 
 26° 7295 
 26:51 26 
 41 38 
 7 6 
 62 | 64 
 40 | 36 
 mi ieee ee: + 
 68 | 66 
 60 | 59 
 55. ae 
 63°) GL 
 BK ae 
 20 2) au 
 2.5: te 
 0 0 
 36 | 34.5 
 om | 20.5 
 1 1 
 13 1 Os) 
 32:3) Sie 
 14 14 
 8 8.5 
 29.o] he 
 8 8 
 44 | 43 
 
 at Which 
 
 Oe eer ee ee 
 
Ultraviolet Light Studies 189 
 
 by timing the rise of the air bubble in the tube and assuming 
 the rate of rise to be inversely proportional to the viscosity.* 
 
 L4 Macbeth 
 /luminome fer 
 
 Llensl \ 2? 
 ) I nolL hs 
 as oy 
 Glass Prism . 
 Cel/ Uranium Screen 
 
 Quartz Tonochromator 
 
 FIGuRE 70 
 
 Apparatus for Determining Light Absorption by Oil 
 
 ‘‘As a further means of studying the action of ultraviolet 
 light and the changes it accelerates, the degree to which such 
 hght is absorbed by the oil was measured. This absorption 
 was determined in the wavelength interval from 3655 A. 
 to 2300 A., using an ultraviolet spectrophotometer. <A dia- 
 gram of the apparatus, as used, is shown in Figure 70. 
 Light from the quartz Uviare lamp passes through the quartz 
 cell containing a thin film of oil and is dispersed in the Bausch 
 & Lomb quartz monochromator. In order to measure visually 
 the intensity of the ultraviolet light transmitted, A. H. Pfund 
 suggested the use of a thin screen of fluorescent uranium glass 
 cemented to a clear glass prism. The screen is viewed from 
 above at an angle of 60 degrees or more, the lens L rendering 
 parallel the Light from the foreshortened image of the slit. 
 When so viewed the fluorescent light 1s particularly brilliant, 
 and is easily photometered by means of the Macbeth illumino- 
 meter. The intensity of the fluorescent hght is proportional 
 to the intensity of the radiation falling upon the fluorescent 
 sereen, and hence a direct measure of the ight transmitted by 
 the oil film is obtained. By so viewing the fluorescent screen 
 at an angle, no difficulty is experienced from ‘‘impure radia- 
 tion’’ in the monochromator, since such ‘‘impure radiation’’ is 
 due chiefly to longer wavelengths, not affecting the fluorescent 
 screen. 
 
 “The quartz cell, containing the oil, consists of two quartz 
 plates, separated at one end by a thin strip of tinfoil. The 
 angle of the wedge so formed, and hence the thickness of any 
 portion of it, is found by measuring the set of interference 
 
 Sisart, Phil, Mag., 1, 395 (1926). 
 
190 Ultraviolet Light Studies 
 
 fringes obtained on reflecting monochromatic light from the 
 two surfaces of the wedge. The transmission of several differ- 
 ent thicknesses of each oil sample was measured to give check 
 
 values. The degree of absorption shown by the oil is best 
 expressed in terms of the absorption coefficient K caleulated 
 
 from the relationship 
 
 bes J10- 
 where 7 = intensity of transmitted light 
 I, = intensity of incident light 
 t — film thickness in centimeters” 
 TABLE 35 
 
 Changes in Physical and Chemical Constants of Oils after Exposure to Ultra-Violet Light 
 
 Exposure’ Refractive Iodine 
 to U. V. Gas Viscosity index at oO. Acid 
 light hours present poises Mol. wt 26° C. (Hanus) No. 
 Raw Linseed Oil : 
 
 0 0.4 173 1.4751 175 3.4 
 12 Air 0.75 910 1A4TT5 171 4.5 
 24 Air 12:5 1290 1.4779 117 TA 
 30 Air 118.0 1785 1.4832 106 8.5 
 
 3 Oxygen 0.6 969 1.4753 169 3.7 
 
 6 Oxygen 2.25 1551 1.4786 127 7.0 
 
 9 Oxygen 22.0 1858 1.4815 113 9.4 
 
 9 Nitrogen 0.55 788 1.4750 160 3.5 
 PAE Nitrogen 2.85 — 1.4785 149 5.5 
 36 Nitrogen 5.25 1220 1.4803 113 5.5 
 
 Perilla Oil 
 
 0 0.50 762 1.4773 181 11.0 
 
 3 Oxygen 0.65 844 1.4780 154 ED 
 
 6.5 Oxygen 5.25 1364 1.4839 143 14.7 
 
 9.5 Oxygen 33.0 1930 1.4851 116 15.0 
 
 Poppy-Seed Oil 
 
 0 0.55 1.4692 123 5.5 
 
 4 Oxygen el 1.38711 123 5.9 
 
 8 Oxygen 4.60 1.4747 105 11.6 
 12 Oxygen 5.25 1.4750 87 12.4 
 
 Soy Bean Oil 
 
 0 1.0 1.4706 119 8.0 
 
 8 Oxygen 2.0 1.4730 114 9.5 
 
 8 Oxygen ef 1.4750 3 lal? 8.5 
 
 Castor Oil 
 
 0 4.95 1.4729 81 Tol 
 18 Oxygen 5.45 1.4738 70 2.3 
 36 Oxygen 18.07 1.4749 — 11.6 
 54.5 Oxygen 47.50 1.4759 70 28.0 
 
 Testing the Oxidation Effects of Ultraviolet Light.—State- 
 ments have been made in the literature from time to time, that 
 the chalking of lithopone is due to the oxidation of zine sul- 
 phide to zine sulphate, and that the latter, being water solu- 
 ble, leaches out and accelerates the weathering of the film. 
 These statements, however, have never been accompanid by 
 experimental data. 
 
 In order to get some information on the subject, a series of 
 paints were made up in this laboratory with 60 per cent. of 
 pigment and 40 per cent. of liquid, the liquid containing 80 
 
 » . 
 oi 
 
Ultraviolet Light Studies 191 
 per cent linseed oil, 15 per cent turpentine, and 5 per cent of 
 lead-cobalt liquid drier. These paints were poured into por- 
 eelain evaporating dishes 14 em. in diameter. The excess 
 paint was then poured out. The dishes were allowed to drain 
 for an hour. The dishes were then placed in direct sunlight 
 for 3 days for drying of the coatings. In practically every 
 instance, the weight of the dried paint added to the dish was 
 from 4 to 5 grams. The area exposed in every instance was 
 200 sq. em. The evaporating dishes were then half filled with 
 distilled water (approximately 100 ec.). One set of the dishes 
 was placed in the window, exposed to diffused daylight and 
 to air currents for a period of 8 days. The other set of dishes 
 was exposed under an ultraviolet are of the mercury quartz 
 type, for a period of 50 hours. During these exposures, the 
 dishes were subjected to slight rocking every hour in order to 
 wet the coated sides above the water surface. At the end of 
 the first eight hours’ exposure, qualitative tests, showed the 
 presence of metallic compounds and sulphate radicles in the 
 first three products tested. 
 
 At the end of the tests, the liquid in the dishes was very 
 carefully filtered and the percentage of metal determined. The 
 results are given in the chart below. 
 
 Grams zine in water Grams lead. in water 
 
 solution solution 
 (ei ae a i, mee oe 
 Ultraviolet Ultraviolet 
 Daylight light ex- Daylight light ex- 
 exposure posure exposure posure 
 8 days 50 hours 8 days 50 hours 
 
 Oe 5 ED 2% 0.011 0.021 ‘ 
 Mamgeesuipuige Paint.............. 0.004 0.017 
 Mer PAINE... ee ee ee ee eee 0.003 0.014 es ae, 
 White Lead (Carbonate) Paint... .... Bae 0.003 0.004 
 
 It would appear from these results that while paint 1s assum- 
 ing its final period of hardening, after the initial drying for 
 three days, the presence of water and light may accentuate 
 the development of soluble compounds. It is probable that 
 the reactions which take place may to some extent be at- 
 tributed to the formation of free acetic or similar acids by the 
 drying linseed oil, and that these acids react with the pigments 
 present in the films to produce water soluble materials. That 
 zine sulphide may be oxidized to zinc sulphate is apparently 
 also possible. The fact, however, that white lead, which con- 
 tains no suphate radicle, becomes soluble to some extent, 
 would further strengthen the theory that during the drying 
 
192 Ultraviolet Light Studies 
 Sn een 
 process, formic, acetic, or other acids of the aliphatic series 
 are developed, and that they react with the pigments present. 
 In the above tests the white lead afforded as much water solu- 
 ble constituents as the lithopone paints, under daylight ex- 
 posure, 
 
 That ultraviolet light greatly intensifies the production of 
 these water soluble products would appear from a study of 
 the results given in the chart. It is probably safe to assume, 
 however, that any pigment which is soluble in acids may under 
 abnormal conditions of exposure to sunlight or moisture de- 
 velop shght traces of water soluble compounds. It might, 
 however, be unsafe to state that the small quantities developed 
 were sufficient to cause chalking. 
 
 It is probable that the above method of studying paints 
 may prove of service to those who have had problems in con- 
 nection with the ‘‘washing’’ of paint. Washing usually takes 
 place on paints which have been applied in damp, cold weather. 
 Such conditions retard the drying. Moisture is absorbed by 
 the film. It apparently forms an emulsion-like gel during the 
 prolonged period of drying. It is probable that this period is 
 the critical one, during which acids are developed by the dry- 
 ing oil. If these acids are retained within the film, it is very 
 likely that soluble salts are formed, which later are indicated 
 in the form of washing; the paints developing, when rubbed 
 with the finger in wet weather, a soap-like, chalky emulsion 
 which may readily be removed. The use of either strong 
 driers, high pigment concentration, or oils of more rapid set- 
 ting and hardening properties, is suggested. 
 
 Darkening of Pugments by Ultraviolet Light—For results 
 on lithopone, the reader is referred to Chapter XIV and to page 
 215 for results on a number of commonly used pigments. 
 
CHAPTER XIV. 
 
 TESTING THE LIGHT-RESISTANCE OF LITHOPONE 
 Erect oF AcIpITty oF VARNISH AND OIL 
 
 The darkening and discoloration of lithopone, due to the 
 action of ultraviolet rays in sunlight, have in the past consti- 
 tuted a serious drawback to the use of this pigment in paints 
 and enamels. During recent years, however, continued re- 
 search on the part of lithopone manufacturers has resulted in 
 the development of much more light-resistant products, as 
 well as great improvement in other qualities. 
 
 The light-resistance of lithopones has been the subject of 
 numerous investigations. There is much difference of opinion 
 among the investigators regarding the nature of the change 
 and the causes of it. The present chapter, however, is limited 
 to a discussion of methods for testing light-resistance. Other 
 physical properties of the samples tested, such as oil absorp- 
 tion, fineness, livering, etc., are treated elsewhere. 
 
 The comparative light-resistance of different samples is 
 readily determined on clear days by exposing them in a suita- 
 ble liquid, on properly mounted panels, to the sun’s rays. Fre- 
 quently, however, atmospheric conditions are such that sun 
 tests cannot be carried out. Moreover, the intensity of the 
 active rays and the relative humidity of the atmosphere varies 
 greatly at different times and in different localities. It is 
 therefore highly desirable to have an artificial light source 
 from which the ultraviolet radiation can be maintained con- 
 stant and which has actinic effects similar to sunlight. Hu- 
 midity, temperature, and other variable factors should be 
 under control. ; 
 
 The quartz mercury vapor are has been extensively used for 
 testing the light resistance of paints, pigments, and dyes, and 
 is a standardized piece of apparatus. As a means of making 
 control tests in lithopone manufacture, it has been found very 
 practical. More recently the iron are has been adapted for 
 this purpose. It is believed that the iron are, when properly 
 constructed and fitted with the necessary devices for regulat- 
 ing and controlling the current, will also prove satisfactory 
 In paint and varnish plant laboratories for certain types of 
 work. It can be readily constructed at a very reasonable cost 
 
194 Light Resistance of Lithopone 
 
 and produces a light practically constant in the intensity of the 
 ultraviolet radiation. The chief advantage of the mercury 
 vapor lamp is the large area of the light source which permits 
 of the testing of large samples or a number of small samples 
 at the same time. However, the proportion of ultraviolet rays 
 transmitted through the quartz tube of the mercury lamp de- 
 creases continuously with age (see Scientific Paper No. 330, 
 U. S. Bureau of Standards). 
 
 Before describing the results obtained in our investigation 
 with the iron are, there is presented herewith a paper on the 
 testing of lithopone, originally prepared for this chapter by 
 Messrs. Breyer, Nelson and Farber. They point out the use- 
 fulness of the quartz mercury vapor lamp as against the iron 
 are, and refer extensively to the testing of all samples of litho- 
 pone in the paint liquids in which they are to be applied in the 
 form of paints. The information they transmit regarding the 
 effect of high versus low acid oils upon the darkening of litho- 
 pone is of exceptional importance. 
 
 Inght Resistance Test for Lithopone-—A sample of three 
 grams of the lithopone is rubbed down to a stiff paste in one 
 part of China wood oil vehicle (a common type of China wood 
 oil—rosin combination vehicle containing lead dryer) and one 
 part naphtha. (Always make the test in the vehicle in which 
 the lithopone is to be used, or at least in a vehicle of the same 
 type and properties as the vehicle to be used.) The mixture 
 of oil with thinner is freshly prepared for each set of tests. 
 The paste is spread on a porcelain plate or palette in a smooth 
 even layer, at least one inch by three inches in area. A stand- 
 ard, or standards, should be run with each set of samples, all 
 being prepared in the same manner. Care should be taken 
 that the pastes of all samples are approximately of the same 
 consistency. If paints are tested use the paint as it comes 
 from the can. 
 
 The palette is put in a warm place and the pastes dried 
 until the glossy surface disappears. (In ease the testing is 
 done in a vehicle yielding a gloss surface, such as a gloss white 
 paint, dry until the surface will stand being submerged in 
 water.) A strip of opaque black paper or a rule is laid across 
 and above the samples to shadow a portion, and the samples 
 are then exposed to the ultraviolet light under a thin layer of 
 water 1/52 inch to % inch deep. (Exposure under water in- 
 sures a uniform relative humidity.) A desirable length of 
 exposure to bring out significant differences in lithopones is 
 
Light Resistance of Lithopone 195 
 SN Sse 
 five minutes at a distance of twelve inches from the light, when 
 the current is 4 amperes at 180 volts across the line. 
 
 Description of Light Used for Testing —The light source 
 found to be most satisfactory for laboratory testing is the 
 Standard Uviare Laboratory Outfit, manufactured by the 
 Cooper Hewitt Electric Company, shown in Wie ie Phis 
 
 { 
 
 3 . 
 
 Al ea 
 
 come 
 : 
 
 se me ™ a 
 
 dp 
 
 FIGURE 71 
 
 Uviare Laboratory Outfit. Composite Detail showing 
 showing two positions of hood. burner holder with 
 Lorizontal type 
 
 burner in position. 
 
 equipment is furnished for either 220 volts direct current or 
 110 volts alternating current. So far it has been considered 
 Superior to other forms of equipment for routine tests on 
 
196 Light Resistance of Lithopone 
 
 denne errr eee 
 
 account of its simplicity of operation, being practically self- 
 regulating. 
 
 The details of the burner and holder are also shown. The 
 burner holder is universally adjustable in all planes and will 
 take either the vertical or the horizontal type of burner. 
 
 The useful life of a quartz burner has been found by experi- 
 ence to be from 1000 to 1500 hours of steady operation, and a 
 new burner can easily be substituted. In practical laboratory 
 
 FIGURE 72 
 
 (A) Uviare light test on seven Lithopones. Time, 5 minutes. 
 
 test work this provides an amply uniform source of light. A 
 burner in use at the time this is written has been used for test- 
 
 mes orane of samples daily for 114 years and is still considered 
 useful. 
 
Light Resistance of Lithopone 197 
 
 Also, since in any ease all tests are run against a standard, 
 
 the behavior of the standard quickly indicates any falling off 
 in the effectivesness of the quartz burner. 
 
 Uviare Tests Comparable with Sunlight Tests Experience 
 has already proven that tests carried out in the above manner 
 are comparable with sunlight tests, and are a true indication 
 
 [Sun Light. 
 
 FIGURE 73 
 
 (B) Sunlight test on seven Lithopones. Time, 2% hours. 
 
 of light resistance. This is also demonstrated by the photo- 
 graphs in Figs. 72 and 73. In these tests seven different litho- 
 pones of varying light resistances have been submitted (a) to 
 ultraviolet light, as described above for five minutes, and (b) 
 to bright sunlight for 214 hours (sample under water). It 
 
198 Light Resistance of Lithopone 
 
 will be seen that in each case there is perfect agreement in the 
 relative light resistance of the lithopones. 
 
 Humidity Must be Controlled During the Test Period.—lIt 
 is a well-known fact, as indicated by the literature on actinic 
 effects, that the presence of moisture increases the rate at 
 which chemical changes are promoted by ultra-violet radia- 
 tions. This is true of the darkening of lithopones. It is, 
 therefore, very important that all comparative tests of this 
 nature be conducted under known and reproducible humidity 
 conditions. Since any condition short of complete saturation 
 is not easily maintained constant or reproduced without spe- 
 cial equipment, the simple expedient of immersing the samples 
 in water is the most reliable means for eliminating the humid- 
 ity variable from the test. 
 
 We would also point out that testing under saturated moist- 
 ure conditions has the further advantage that the lithopone 
 is being tested under the most trying conditions it can ever be 
 required to meet in practise. 
 
 Effect of Vehicle on Results of Light Resistance Tests— 
 Under the foregoing description of the test method it was also 
 suggested that the vehicle is an important factor in the results 
 of light resistance tests and that tests on lithopones intended 
 for paint purposes should be made in a practical paint vehicle. 
 
 A number of lithopone users have insisted that water or 
 glycerol pastes should be used in testing for light resistance. 
 From every standpoint this is wrong, unless the lithopone is 
 actually to be used in water or glycerol vehicles. That such a 
 method is fundamentally wrong and misleading is amply dem- 
 onstrated by the tests in Fig. 74. 
 
 In Fig. 74 the original lithopone is rubbed down in (1) regu- 
 lar flatting oil test vehicle (2) water and (3) glycerol. There 
 is no agreement in the results and, obviously, only the test in 
 the oil vehicle can be accepted as a criterion for lithopones 
 to be used in oil paints. 
 
 Further, the use of water and glycerol pastes may lead to 
 
 extremely erroneous conclusions about improvements in the ~ 
 
 quality of lithopones. Lithopones can easily be ‘‘doped’’ so 
 as to vary their light-resisting properties. In Fig. 74 the same 
 lithopone has been so ‘‘doped’’ and tested in (4) flatting oil 
 vehicle (same as above), (5) water and (6) glycerol. It is 
 important to note that while this lithopone now shows per- 
 fect light resistance, in both water and glycerol pastes, there 
 has been no improvement with the flatting oil vehicle. There- 
 fore, it would be a mistake to say that the quality of the litho- 
 pone had been improved. 
 
Light Resistance of Lithopone 199 
 
 Preferable to Test in Same Oil Vehicles as Used in Practice. 
 —The light resistance properties of lithopones are also affected 
 by variations in the properties of the oil vehicle themselves. 
 Fig. 75 illustrates how very important this factor may be. A 
 
 Light Resistance test. 
 Brpesed te Ultra Violet 
 
 Lignt for five(5)minutes, 
 
 Orignal 
 Rubbed in oi 
 
 = / 
 
 Treated ; 
 Rubbed 
 
 * 
 
 LPS rtemisinitics 
 
 FIGURE 74 
 
 Comparison of light resistance tests on the same Lithopone in (1 and 4) 
 oil vehicle (2 and 5), water, and (3 and 6) glycerol. 
 
 single lithopone was tested in a series of vehicles typical of 
 the principal oil products on the market. (In these tests the 
 
200 Light Resistance of Lithopone 
 
 Figure 75 i 
 
 Acid Acid ; 
 
 No. No. 3 
 
 1. Raw Linseed Oil......... 8. Standard Acid Refined Lin- a 
 2. Improved Raw L. Oil..... 5-7 seed Oil 4.5 Hage % 
 3. Alkaline Refined Varnish 9. White Acid Refined Oil... 6.5 5 
 OL. EP ae yo dee ake ee 10.. Pale: Grinding jcieees eee z 
 
 4. Alkaline Refined Oil...... 0.5 11. Boiled Qi ty a scone q 
 5. Alkaline Refined Oil Re- 12. Kettle Bodied ...5...4..2.5 ——= ; 
 frigena ten s.io5) ay se oe 13. Blown Bodied Gilly 2p CU : 
 
 6. Alkaline Refined Oil...... 3.0 14. Boiled Ol] sc. <2 eee bs 
 7. Acid Ref. Oil Refrigerated 10 15. Treated China Wood Oil.. 5-6 7 
 Light Resistance test on a Lithopone in yarious oil vehicles. : 
 
 oils have been thinned with volatile so as to dry to a semi-flat- 
 surface.) Very few of the results check one another. : 
 If we consider the results further, we find that, generally, 
 the important determining factors appear to be the acid num- ; 
 ber of the vehicle, and whether the oils are acid or alkaline : 
 i 
 
Light Resistance of Lithopone 201 
 
 refined. The presence of acid materials apparently increases 
 the light-resisting properties. 
 
 Fig. 76 presents still further evidence that effects of changes 
 in the properties of oils, which are brought about in the process 
 of manufacturing, must be seriously considered as factors in 
 choosing the vehicle in which to conduct light-resistance tests. 
 
 : [Alkaline Refinea, Jo | 
 #/ 
 
 | Acid Refined, 
 
 ads 
 
 # 
 
 [Kettle Bodied 
 
 FIGURE 76 
 
 Test further illustrating effect of vehicle treatment on the light resisting 
 properties of a Lithopone. 
 
 This effect of increased acidity is also illustrated in Figs. 77 
 and 78 (A) and (B). (A) shows the effect of increasing acid 
 numbers from 1.0 to 20.0 in an alkaline refined linseed oil. The 
 acidity was increased adding linseed fatty acids. (B) com- 
 pares a treated China wood oil vehicle with a series consisting 
 of increasingly acid raw China wood oils. Fatty acids of 
 China wood oil were added to increase the acidity of this 
 vehicle. 
 
 That commercially used flatting vehicles might differ very 
 widely in their influence on the light-resistance properties 
 
202 Light Resistance of Lithopone 
 
 Acia Number 1.6 
 
 Acid Number 5&,9 
 
 Acid Number 10,0 
 
 * 
 
 Acid Number L5,0 
 
 Acid Number 20,0 . 
 
 FIGURE 77 
 
 (A) Alkaline Refined Linseed Oil. 
 
 of a lithopone, follows as a natural deduction from what has 
 just been said. But this is more forcefully demonstrated as 
 an actual fact by the tests with two flat wall vehicles illus- 
 trated in Fig. 79. In this case vehicle (A) probably is a com- 
 bination of linseed oil with some China wood oil. The acid 
 number of this vehicle averages about 13. Vehicle (B) is a 
 straight treated China wood oil vehicle having an average 
 acid number 5-6. 
 
 All of the tests just presented suggest that certain precau- 
 tions must be accepted as essential in making reliable com- 
 parative light-resistance tests on hthopones, viz: 
 
 (1) Always run the test lithopone sample against a standard 
 or standards. 
 
 (2) The humidity conditions must be maintained constant 
 if different tests are to be considered at all comparable. 
 
 (3) The test vehicle must be of the same type and similar 
 in properties to the vehicle used in practice. 
 
 (4) Watch the test vehicle for any variation in properties. 
 This refers to variations in acidity, especially. 
 
 ye = 
 a on 
 
 ef, ae ae 
 
Light Resistance of Lithopone 203 
 
 Iron Arc Tests.—The results given in the following pages 
 were obtained with an iron are which was designed, in its 
 original form, by Dr. A. H. Pfund.* The intensity of the ultra- 
 violet radiation varies with the current passing through the 
 are. It is therefore necessary that the amount of current be 
 properly adjusted by inserting a variable resistance in the line. 
 The length of the are must be readily adjustable so that the 
 
 | “nadea's os tty Welae Le Rew ch 
 
 a Wood see if the tece 
 She ac nate nunber Tease 
 E ees Banter! meters 
 
 Treated China Wood 
 
 FIGURE 78 
 
 (B) China Wood Oil Vehicle. 
 Effect of increased acidity of vehicle on light resistance of a Lithopone. 
 
 proper potential across it may be maintained. It has been 
 found that the are constructed as described herein burns best 
 at a current of five amperes with a potential of 40 volts be- 
 tween the electrodes. 
 
 The method used by the writer in making these tests was 
 essentially that of Eastlack and Booge: who have furnished 
 the following description. 
 
 a. Principle of Method.—The sample of lithopone in the 
 form of a water paste is exposed under a quartz cover glass to 
 
 *Astro-physical Journal, Vol. 27, p. 296 (1908) ). 
 
204 Light Resistance of Lithopone 
 
 oe 
 
 §/11/21, 
 
 he 
 
 FIGURE 79 
 
 Difference in the light resistance of a Lithopone in two commercial flat 
 wall vehicles. (A) Probably a combination Linseed Oil-China Wood Oil 
 vehicle. Acid Number 18. (B.) <A treated China Wood Oil vehicle. Acid 
 Number 5-6. 
 
 the action of a standard iron are, at a distance of 10 em. A 
 portion of the sample is covered with opaque material. The 
 time required to produce the first appearance of darkening, 
 as indicated by a faint but definite line of demarkation be- 
 tween the exposed and unexposed portions of the sample, is 
 taken as a measure of the light-resistance of the sample. 
 
 b. Apparatus and Materials Required: 
 
 Iron are with voltmeter, ammeter and rheostats. 
 
 Sample holder with an optically clear dise of native quartz 
 crystal (30 mm. dia. x 1.5 mm. thick).* 
 
 Spatula—hard rubber, small. 
 Beaker, 50 ce., or glass plate for mixing paste. 
 Distilled water. 
 
 *Comparative tests by three different laboratories (see below) indicates 
 that exact adherence to the specifications for the quartz dise is important. 
 
 al as Si os i ayy 
 
Light Resistance of Lithopone 205 
 
 c. Procedure: 
 
 1. Preparation of Sample.—Put 3-5 g. of the hthopone into 
 a 50 ec. beaker (or on a glass plate), and about 2 cc. of dis- 
 tilled water, and with a small rubber spatula mix the water 
 
 ENE | S WSs = 
 
 FicurEr 80 
 
 Diagram of iron are equipment used in our work. 
 
 and lithopone in such proportion that a smooth, moderately 
 thin paste is obtained. Place a portion of the paste on the back 
 of the quartz disc and press a small piece of glass down over 
 the paste to prevent its drying out during the test. The sur- 
 
206 Light Resistance of Lithopone 
 
 face viewed through the quartz dise should be uniform and 
 free from air bubbles. Place the plate carrying the dise in 
 the sample holder at a distance such that the surface of the 
 sample is 10 em. from the center of the are. Cover a portion 
 of the sample with a strip of thin brass or other opaque 
 material. 
 
 2. Starting and Operating the Arc.—Before starting the 
 are see that the upper electrode is fairly free from ferrie oxide 
 and is adjusted to extend 14 inch to %% inch below the radiator 
 and is centered directly above the lower electrode. Now close 
 the main switch, bring the electrodes into contact with each 
 other and quickly separate them—thus starting the are. 
 
 The shallow cup on top of the lower electrode should be 
 completely filled with a bead of magnetic oxide. If this is 
 not the case, raise the current to about 10 amperes until the 
 top of the upper electrode is in a thoroughly molten condition. 
 By quickly bringing the electrodes into contact and then sepa- 
 rating them again, the drop is transferred to the lower elec- 
 trode. The 10-amp. current is then maintained until the top 
 of the upper electrode is again molten, so as to obtain a sym- 
 metrical bead on the upper electrode also. 
 
 Now cut in resistance until the current is adjusted to exactly 
 9 amperes, using the large rheostat for coarse adjustments 
 and the small rheostat for fine adjustments; also adjust the 
 distance between the electrodes until the potential between 
 them is exactly 40 volts.* | 
 
 3. Exposure of Sample and Interpretation of Results.— 
 When the arc is operating smoothly at 5 amperes and 40 volts, 
 open the shutter, exposing the sample to the are, and close it 
 again at the end of 30 seconds. Examine the sample care- 
 fully in a good light to see if the exposed portion has been 
 darkened (as indicated by a line of demarkation between the 
 exposed and unexposed portions). If not, another portion of 
 the sample is exposed for 60 seconds, or, if the sample was 
 appreciably affected in 30 seconds, the next trial is made at 
 15 seconds. For each exposure the position of the strip of 
 brass protecting part of the sample must be changed. 
 
 Repeat the exposure of the sample to the are (using fresh 
 portions of the paste, if necessary) until the time required to 
 produce the first appearance of darkening has been satisfac- 
 
 *In a private communication Pfund and Eastlack state that a somewhat 
 steadier arc may be obtained by using a current of 35 volts and 6 amperes. 
 This gives about the same wattage and therefore the Same intensity of light 
 as a current of 40 volts and 5 amperes. 
 
 at 
 
Light Resistance of Lithopone 207 
 
 torily determined. The precision which is regarded as satis- 
 factory for exposures of different lengths is indicated below: 
 
 Total time for 1st “End-Point” should be 
 
 darkening. located within— 
 Se nace oles os sk ss vias op ceeded ccccccccunce 1 sec 
 sls eco s cs me sont sc ove vce ode cons ccececuc, Ps 
 
 a ee eal gs iobia's ves ev vies dela oe cca bance cay Bes 
 
 MS 0S aie Ss kk vice cn cc ess wo ecckcanccnncn. LO. 
 
 I ee. Loic cig.ds s's os nk vv eso dooce cecseccwer PAW ak 
 
 oo vig eek os esis ale Gc ev be 0s boehckiede 30 
 
 The number of seconds required to produce first darkening 
 is recorded as a measure of the light-resistance of the sample. 
 Samples which show no darkening in 300 seconds (5 minutes) 
 may be regarded as ‘‘light-stable,’’ although for all practical 
 purposes samples which show no darkening in 60 seconds will 
 not be appreciably affected by sunlight when used as a pig- 
 ment in oil paints. 
 
 Inthopone Samples Examined.—In the work carried out by 
 the present writer, four series of samples were tested. They 
 are designated as follows: | 
 
 Series A: Laboratory samples. A-1, A-2, and A-3 were 
 originally obtained for specific gravity work and were about 
 four years old. The other samples of this series were from 
 two to three years old. None were obtained for light-sensitive- 
 ness tests. 
 
 Series B: Set of five samples of varying degrees of light- 
 sensitiveness obtained from the Bureau of Standards which 
 had been sent to the Bureau by Dr. Booge. 
 
 Series C: Standard samples of varying degrees of light- 
 sensitiveness sent by Dr. Booge. 
 
 Series D: Samples from factory batches obtained direct 
 from the manufacturers. These represented current com- 
 mercial lots. 
 
 Tests on Water Pastes of Lithopones.—As pointed out in 
 Hastlack and Booge’s communication, lithopone is far more 
 sensitive in water paste than in any other vehicle. When ex- 
 posed to the sun’s rays some samples darken perceptibly in a 
 few minutes, while all except one of those examined were more 
 or less discolored at the end of one hour under prevailing at- 
 mospheric conditions. Darkening under the influence of the 
 iron are is sometimes a question of seconds only, while very 
 few samples will stand exposure for ten minutes without 
 discoloration. 
 
 Results obtained with the iron are on water pastes of the 
 twenty-five samples examined are given in Table 36. 
 
208 
 
 Light Resistance of Lithopone 
 
 In Table 37 are given the results of tests on series C and 
 
 series D upon exposure to the iron are and to sunlight. 
 
 The 
 
 samples are arranged according to increasing light resistance. 
 The table indicates that for water pastes the order of darken- 
 ing, in general, is the same by the two tests. 
 
 TABLE 36 
 Iron Arc Tests—Water Pastes 
 
 Sample Time for 
 
 No. darkening. 
 Fe Ge ee re ee OM ETON 6 seconds 
 | ee Nir Peet 20 seconds 
 AWB oe eb nee ee lb ony Gee woe Sle le oelpoai ua lors bi epee es eg a 5 seconds 
 De ee ene ere IE PRM EARE RPK 60-70 seconds 
 AD col cece wa bebe da waders ew ele eles piecelece ss@ie at Sie. 4 seconds 
 7: eee ee REEL 650-700 seconds 
 AMT Sc cine cie ae cee ecw ewe ep cw a whats Mvaitee oa toe ie ita a 6 seconds 
 to, a ME PI er 250-800 seconds 
 Baloo .4 5 oka be ek a eee ee unaffected in 1200 seconds 
 Boo cos vc cee ee oe aca eee Wik O° ag 5 a aibaael aap eee a 150 seconds 
 1 5 os ee re ea 30 seconds 
 Br sc sce cee oe cee wie a eu wie coe gu 6 alop ip wlelie aie see 16 seconds 
 BR ie Ske bie cis nie cle ys won gio ale em ale te Senate een er 4 seconds 
 CPD ble eck wna weedane reap geen unaffected in 1200 seconds 
 0S) an re MRE 135 seconds 
 CO-B nies vee occ nc 6 oc3.8)e.ce hin ee, psoite oiete glare a a aieaicet atest 40 seconds 
 De4 ec bine oe eee wn wip 0 asa win a nw ooh eile a gilin cs inet a 18 seconds 
 CHB ok hk cen we la e's) oc pre apna ele le @ ele a abe) eiea: GleAy ie geen i 4 seconds 
 LO ra rrr me ge 95° seconds 
 D8 ook baie since ww wwe 08 we wy ncn ee an ge leah ee eae 240 seconds 
 D-Backs ae we md eie'a bes ew Siw le ie kn uel gel gen 85 seconds 
 D-4 en vee oe on deeb 6% ge Dy Se gies ae lel ec apr eee 1200 seconds 
 DB ipa cae ie hen eon en bbw oe lela © alec big) Gln ene ligne iene 950 seconds 
 | OS 5 arr mrer ar are re rE Be 30 seconds 
 DoT iis ep ware oe win we, gnlay wk we pleiy, vault te ee eae a 600 seconds 
 
 TABLE OU 
 
 Order of Darkening—Water Pastes of Lithopone. 
 Slides for Sunlight Tests Prepared According to the Method of Hastlack 
 
 and Booge. 
 Sunlight tests. 
 
 oh FF 
 Color after one hour 
 
 Sample. exposure to sunlight. 
 CE oihoe aheie cede A ate edo Almost black 
 OSE iy lal wie a nN tee ee Very dary gray 
 D8 2s Lae ee ree en ee Dark gray 
 COD: new elvan ee OOS eR Dark gray 
 Teh at REPRE Att ete, seca ehatangter s Yellowish gray 
 | Ee a Oe er pe ga Man es ee Gray 
 CTD Sal geal Grp cote ae I gee Yellowish gray 
 DIZEE iee a asst patente ee Gray 
 DS Sr ee sae reat era Gray 
 DAO on po ow eee earns are ees Slightly gray 
 Tris eee aceaeani es Se ae ieee ee Very slightly yellow 
 CA imate eek a Sek ca Very slightly yellow 
 
 Iron Are Tests 
 ease ae ,.| 
 Time for darkening. 
 4 seconds 
 18 seconds 
 30 seconds 
 40 seconds 
 85 seconds 
 95 seconds 
 135 seconds 
 240 seconds 
 600 seconds 
 950 seconds 
 1,200seconds 
 Unaffected in 1,200 seconds 
 
Light Resistance of Lithopone 209 
 
 The day on which the sun exposures were made was very 
 hot and the sky somewhat hazy but not cloudy at any time 
 during the exposure. 
 
 The discoloration of samples D-7, D-4, and C-1 in the. sun 
 tests faded completely in a few hour s. The rest remained 
 permanently darkened although D-2, D-6 and C-3 faded out 
 to a considerable extent. 
 
 Tests on Glycerine Pastes of Litho pones. —Lithopones will 
 also darken when glycerine is used in place of water in mak- 
 ing the paste. The time required for darkening is somewhat 
 greater than for water pastes. Table 38 gives the results ob- 
 tained on the samples of Series C. 
 
 TABLE 388 
 Iron Are Tests on Glycerin Pastes. 
 I ed Ly vciwleis vee vleeceacwees Unaffected in 1,800 seconds. 
 I Te cc cee eee eee Darkened in 720 seconds. 
 he ek ie ews PE ee eh ee View gies we wie’ Darkened in 120 seconds 
 SE I a Darkened in 45 seconds. 
 ae twee dt ew eases eves Darkened in 12 seconds. 
 
 TABLE 39 
 
 Sun Tests on Dammar Varnish Pastes 
 
 Final Order 
 
 Sample 2 Hours 5 Hours 12 Hours 20 Hours of 
 Darkening 
 ee 
 D-1 Unaffected Unaffected Very slightly Bluish gray C-5 
 darkened darkest 
 
 bluish gray 
 
 oe eee es el eee 
 
 D-2 Unaffected Unaffected Unaffected Apparently C-4 
 
 unaffected 
 D-3 Unaffected Unaffected Very faintly © Gray D-6 
 darkened 
 a a nce 
 D-6 Unaffected Slightly Somewhat Quite gray C-3 
 affected darkened 
 Eee 
 C-2 Unaffected Unaffected Faintly Slightly D-1 
 darkened bluish gray 
 C-3 Very slight Slightly Somewhat Quite gray D-3 
 indication darkened darkened 
 IS ces 
 C-4 Very slightly Somewhat Dark gray Very dark C-2 
 darkened darkened gray 
 C-5 Slightly Very dark Bluish black Bluish black D-2 
 
 darkened gray lightest 
 
 I~ a anna 
 
210 Light Resistance of Lithopone 
 
 Tests on Varnish Vehicle Pastes of Lithopones.—Some 
 manufacturers and users of lithopone rightly prefer to make 
 the test in oil or varnish vehicles in order to more nearly 
 approximate actual service conditions. 
 
 Tests were also made to determine whether the results ob- 
 tained in water pastes would run parallel with the results of 
 sun tests on pastes in oil or varnish vehicles. For this pur- 
 pose Dammar Varnish and also a commercial flat wall paint 
 liquid were used. The tests were made on eight representa- 
 tive samples which darkened when exposed to the iron are, in 
 varying periods of time. The results of these tests are given 
 in Table 40. 
 
 It will be observed that the order of light stability shown in 
 this table agrees well with that of Table 37. Since there is no 
 sharp point or narrow limit of time in which darkening can 
 be said to occur in the sun tests, and moreover, the color of the 
 discoloration varies considerably with different samples, slight 
 discrepancies are to be expected. 
 
 TABLE 40 
 
 Sun Tests on Flat Wall Paint Liquid Pastes 
 eee eee 
 
 Final Order 
 Sample 2 Hours 5 Hours 12 Hours 20 Hours of 
 darkening 
 eee 
 D-1 Unaffected Unaffected Very faintly | Somewhat C-5 
 darkened darkened darkest 
 yellowish 
 gray 
 D-2. Unaffected Unaffected Unaffected Apparently C-4 
 unaffected 
 D-3 Unaffected Unaflected Slightly Slightly D-6 
 yellow 
 D-6 Unaffected Unaffected Faintly Quite yellow D-1 
 darkened 
 nnn OMEN 
 C-2. Unaffected Unaffected Faintly Slightly C-2 
 darkened yellow 
 C-3 Unaffected Unaffected Apparently Very light D-3 
 unaffected gray 
 C-4 Unaffected Unaffected Very slightly Yellow C-2 
 darkened 
 
 C-5 Very slightly Very dark Very dark Almost black D-2 
 darkened brown brown ~ lightest 
 
 AS lee 
 
 atye = 
 
 ae eae aad eee 
 
Light Resistance of Lithopone 211 
 
 Efforts were made to check the sun tests on Dammar var- 
 nish and flat wall paint liquid pastes with iron arc tests. ‘The 
 time required for darkening in these liquids is, however, so 
 great as to make the iron are rather impractical for these 
 pastes. The results obtained are given in Table 41. 
 
 TABLE 41 
 Iron Arc Tests on Paint Liquid Pastes 
 Time required for darkening Time required for darkening in 
 
 Sample in Dammar varnish paste flat wall paint liquid paste 
 
 ae ae Unaffected in 3,600 seconds Unaffected in 3,600 seconds 
 2 a ae Darkened in 500 seconds Darkened in 1,400 seconds 
 OE a Unaffected in 3,600 seconds Unaffected in 3,600 seconds 
 TE ee eee Darkened in 3,600 seconds Unaffected in 3,600 seconds 
 
 Comparison of results obtained in different laboratories.— 
 Light stability tests were made on the samples of series B and 
 series C in water paste. Similar tests were also made by 
 Eastlack and Booge, and at the Bureau of Standards. Results 
 obtained in three laboratories are given in Table 42 for the 
 sake of comparison. 
 
 The apparatus used by the writer and by Hastlack and 
 Booge are described above. The following description of the 
 apparatus used at the Bureau of Standards was submitted by 
 Dr. J. G. Thompson, who made the tests, the results of which 
 are given in Table 42. 
 
 Thompson Arrangement of Apparatus.—The source of 
 ultra-violet light was a small iron are operating at 5 amperes 
 and 40 volts. The electrodes were ordinary soft-iron rods. 
 The dry samples were rubbed up to moderately thick pastes 
 with water, using a rubber spatula. The paste was spread on 
 one side of a plate of crystalline quartz aproximately 1 inch 
 x 21% inches x 14 inch thick. The quartz plate was mounted 
 in a holder so that the ultra-violet light must pass through 
 the quartz to reach the paste, the quartz-paste surface being 
 10 em. distant from the center of the are. The remote sur- 
 face of the paste was covered with a glass microscope slide to 
 prevent too rapid evaporation of the water. 
 
 The results reported are average values based on more than 
 one determination. 
 
 The cause for the discrepancies is not yet apparent, but is 
 probably due partly to errors of observation in judging the 
 time required for first darkening. Some operators can detect 
 fainter shades of darkening than others. Hastlack and Booge 
 
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 have found that the composition of different types of iron 
 rods forming the electrodes has only a slight influence on the 
 results. Probably the greatest source of error arises from the 
 fact that different pieces of quartz used vary in their trans- 
 parency to ultra-violet light. 
 
 According to Luckiesh* crystalline and fused quartz differ 
 considerably, the crystalline variety usually being transpar- 
 ent further into the ultra-violet region than the fused. Differ- 
 ent crystals also vary considerably in transparency. The 
 writers used a dise of fused quartz one inch in diameter and 
 one-eighth inch thick. In order to determine whether the 
 particular piece of quartz used would affect the results to an 
 appreciable extent, the writers borrowed the piece which had 
 been used at the Bureau, using it in connection with their are. 
 The results checked those of Thompson’s quite closely as 
 shown in Table 43. The lower values obtained by Eastlack 
 and Booge are no doubt due to their use of an optically clear 
 quartz dise of only 1.5 mm. thickness. 
 
 TABLE 48 
 Results Obtained at Two Laboratories Using the Same Quartz Glass 
 Institute of Paint and Var- 
 
 Sample Bureau of Standards. nish Research 
 
 No. 2 Darkens in 80-90 seconds Darkens in 8&5 seconds 
 No. 3 Darkens in 30-35 seconds Darkens in 30 seconds 
 No. 4 Darkens in 16 seconds Darkens in 14 seconds 
 No. 5 Darkens in 4 seconds Darkens in 4 seconds 
 
 The following comments were made by one observer to 
 whom this chapter was submitted: 
 
 Apparently temperature plays an important part in the 
 eolor changes that take place when lithopone is exposed to 
 sunlight or to ultra-violet light from laboratory lamps. It is 
 considered that with rise of temperature to a certain extent, 
 lithopone becomes less sensitive to change. Undoubtedly the 
 condition of the atmosphere in which the tests are made has 
 something to do with the effects. It has been found, for in- 
 stance, that darkening is much more rapid in a hydrogen 
 atmosphere than in ordinary air. Tests, however, indicate 
 that darkening will not take place in an atmosphere of ozone, 
 and in most cases will not take place in oxygen. One investi- 
 gator some time ago rubbed up a sample of lithopone in water 
 on a glass slide, and placed it in a U viol tube having a 2-hole 
 rubber stopper, through which moist hydrogen was bubbled. 
 
 *Ultra-violet Radiation, page 73 (1922). 
 
214 Light Resistance of Lithopone 
 
 The slide was exposed to the light of a Macbeth printing lamp, 
 specially cored carbon rods being used. It was found, for in- 
 stance, that even zinc oxide would darken under these con- 
 ditions, as well as certain copper salts, and the result was 
 attributed to a reducing action. 
 
 It has been known for a long time that lithopone may be 
 made sunproof when ground in water paste, by the addition of 
 small amounts of salts, such, for instance, as ammonium phos- 
 phate. However, when the same mixture is dried and mixed 
 with oils and exposed it is apt to darken very rapidly. 
 
 In commenting upon the tests outlined in this paper, an- 
 other well-known investigator gave the following information: 
 
 ‘“Sunlight Test—We keep the samples moist by putting the 
 glass slides on a piece of common blotting paper, kept moist 
 by a small glass jar filled with water, and a cotton wick leads 
 from the glass jar and is laid upon top of the blotter. In this 
 way we have found we could keep samples moist for two or 
 three hours, which is sufficient to get a good sun test. 
 
 We have found that glass once used will absorb energy from 
 the sunlight, and if this same glass is used for a second test 
 the lithopone, if it is very sensitive to light, will turn without 
 being exposed to the sunlight. We therefore make it a point 
 to use new glasses for sun tests all the time. Using a glass 
 which has already been exposed might make a lithopone 
 turn in 15 minutes as bad as it otherwise would in 30 minutes, 
 and thereby give you a wrong test. 
 
 “Comparison with Paint-Out Tests——We have found the 
 humidity is the main factor in making lithopone paints turn in 
 sunlight. We have made hundreds of experiments with flat 
 wall paints and gloss paints, and find the flat paints to turn 
 much quicker than gloss, and if the humidity is below 60 per 
 cent. the modern lithopones will not turn at all, while the old 
 lithopones will turn as black as coal. These tests are made on 
 pine boards painted with regular flat or gloss paint, one-half 
 covered ite paper, the other half exposed to the sunlight on 
 the south side of our laboratory.”’ 
 
 Concuusions.—The light resistance of lithopone may be 
 tested by exposure either to sunlight or to an artificial source 
 of ultra-violet light. Tests made on a number of samples in- 
 dicate that the two methods yield concordant results. While 
 the order of darkening of a series of pigments is the same by 
 the two methods, a considerably longer time is required for 
 the sun tests. 
 
 ~ ae 
 
Light Resistance of Lithopone rg 
 
 enn ere ee rr 
 
 For research work where there is trained personnel, the iron 
 are could be a supplementary part of the laboratory equipment, 
 since the intensity of the ultra-violet radiation can be main- 
 tained most constant over a long period of time. For this 
 reason, the iron are could be used to occasionally check up the 
 intensity of the quartz tube mercury vapor lamp. In other 
 words, it could be used as a standardization instrument. 
 
 For ordinary paint factory use, it is suggested that litho- 
 pone be tested in the liquid in which it is to be used in practice. 
 
 For this purpose, a quartz tube mercury vapor lamp 1s most 
 useful, because several samples of lithopone in different paint 
 
 Hnuids can be exposed at the same time. In five minutes re- 
 sults may be obtained and a photographic record made. 
 
 Errrot oF Uurra-VIoLtet Light on Pigments OtTHer ‘THAN 
 LITHOPONE 
 
 The property of darkening when exposed to ultra-violet 
 light is shown to some slight extent by other pigments than 
 lithopone; in fact, even by some inert pigments. While sev- 
 eral pigments examined, notably antimony oxide, showed a 
 change, the effect is usually only a slight graying which is not 
 ereatly accentuated by continued exposure to the light. While 
 lithopone darkens most quickly in water paste, all other white 
 pigments examined, if they changed at all, were most readily 
 affected in glycerin paste. Results of tests on white pigments 
 other than lithopone are given in Table 44. It was indi- 
 eated by study of several samples that the presence of small 
 quantities of water soluble salts or the effect of certain meth- 
 ods of heat treatment were accelerators of darkening. 
 
 TABLE 44 
 
 Iron Are Tests on White Pigments Other Than Lithopone 
 The term “darkening” refers to a slight “graying.” 
 
 Sample Water paste. Glycerine paste. 
 EE yk tne so ee ee eee Unaffected Darkened 
 Basic Carbonate White Lead ....... Unaffected Darkened 
 Basic Sulphate White Lead No. 1.... Unaffected Unaffected 
 Basic Sulphate White Lead No. 2.... Darkened Darkened 
 er ec ek ses sce eve sence ee Darkened Darkened 
 ein 0 a Unaffected Darkened 
 Soo. 6 5 y's ahs ee cc eos pe ofa as Unaffected Unaffected 
 Te ep kes pace eves ee as Unaffected Unaffected 
 Zirconium Oxide (Hydrated)........ Unaffected Unaffected 
 
 Rs gle als ie  a'v.e's vie ve wiersherd ons ¢ Unaffected * Darkened 
 
216 Light Resistance of Lithopone 
 
 Results on some colored pigments are given in Table 45. 
 It is interesting to note that pigments high in lead oxide are 
 apparently more subject to ultra-violet light effects than some 
 others. For instance, dry litharge, even when placed in a glass 
 bottle, will show on the surface some color change when ex- 
 posed to diffused daylight in a laboratory over a long period 
 
 of time. 
 
 TABLE 45 
 Iron Are Tests on Colored Pigments 
 Sample. 
 
 Toluidine Lake Scarlet. oo. 7s). ca scabee ee Unaffected in 1,800 seconds 
 Tron: OF Me. SS ae ee ee eee Unaffected in 1,800 seconds 
 Chrome Yellow  CBASi€) <i. ave.s5 asc oe Darkened in 1,500 seconds 
 Lat Rare: eo ied s ecstasy ere 8 eee he oe ee Darkened in 45 seconds 
 
 Light Chrome Yellow (Neutral)......... Unaffected in 1,800 seconds 
 Réd Lead $s ck ks es ee a eee Unaffected in 1,800 seconds 
 Chrome Orange....0s a. Wels eee Unaffected in 1,800 seconds 
 Para ‘Toner icck os cs ee wae he oe eee Unaffected in 1,800 seconds 
 Brilliant Orange Lake... 2.4.0: 05 see Darkened in 1,800 seconds 
 Chrome. Yellow -Oranges." 3024.) ase eee Darkened in 1,800 seconds 
 Ghroime: Green Ge Pic ies sa seats Faded somewhat in 1,800 
 Prenssian. BING. 453 eee eee eee eee . Unaffected in 1,800 seconds 
 
 Zing = Dustsc oh cstekoche Oo ee ee ee Unaffected in 1,800 seconds 
 
 seconds 
 
CHAPTER XV 
 
 COLOR SYSTEMS, COLORIMETERS AND SPECTROPHOTOMETERS 
 
 Paint manufacturers have often felt the need of defining and 
 preserving standards of color. The methods in use at the 
 present time are unsatisfactory. The most widely used method 
 of preserving standards of color is by means of painted color 
 chips, which may exhibit a slight change over a short period 
 of time, depending largely upon the conditions under which 
 they are stored. The same difficulty is occasionally met in the 
 ease of tinned standards either ground as a paint or ground 
 in light-colored paraffin oil or in glycerin (see Page 255). It 
 has been realized for some time that instruments were being 
 made available by means of which a color could be recorded 
 and the results kept for further reference. The majority of 
 systems for color* measurement are open to certain complica- 
 tions and difficulties of a fundamental character, particularly 
 those dependent upon the use of secondary standards which, 
 in themselves, have little or no definite relationship to each 
 other and which could be translated into fundamental physi- 
 eal units only by spectrophotometric analysis of each ind1- 
 vidual color. Consequently little study has been given to them 
 in connection with their possible use in the paint trade. 
 
 In this chapter an attempt has been made to describe, clas- 
 sify, and comment upon the various systems of color nomencla- 
 ture and to indicate the usefulness and limitations of various 
 
 colorimeters and spectrophotometers. That some of these in- 
 struments will soon come into wide usage in the paint industry 
 is believed probable. Some enthuisasts even believe that the 
 curve obtained by reading a color upon such instruments may 
 
 *Color as one perceives it in an object is simply psychological or 
 optical sensation. We say, for instance, that lamp-black is black, and the 
 Sensation produced is due to the fact that the physical structure of the 
 pigment causes the absorption of nearly all visible light rays that fall upon 
 it. When these same light rays fall upon zine oxide, they are practically 
 all reflected and we say that this pigment is white. Similarly we have the 
 sensation of red from a pigment absorbing all rays except those that give 
 a sensation of red, while from a green pigment we have reflected only those 
 rays that give the sensation of the particular hue of green that appears. 
 How simple would be the preparation of all colors if we could so change by 
 a simple process the physical structure of some element like carbon so that 
 it would reflect red, green or blue in such proportions as to give the hue 
 we desired. 
 
218 Color Systems, Colorimeters, Etc. 
 
 be made the basis of purchase where exact standards are 
 required. 
 
 The descriptions and comments which follow are based, 
 wherever possible, upon actual examination or operation of 
 the method or the instrument. When this was not possible, 
 the available literature on the subject was searched for the 
 necessary information. References to original papers treat- 
 ing the subject in much greater detail than was possible here 
 have been given throughout the chapter. A list of some of the 
 more widely known books on the subject of color in general 
 will be found on Page 255 for those who wish to make a more 
 detailed study. 
 
 The writer is indebted to M. Rae Paul for valuable sugges- 
 tions in reviewing this chapter. 
 
 CoLor SyYSTEMS OR CHARTS 
 
 Numerous attempts have been made to display on color 
 charts or cards large numbers of colors arranged in a definite 
 order. These color charts or color atlases, as they are some- 
 times called, have a wide use where an approximate match is 
 all that is required. The almost infinite number of colors has 
 made it nearly an impossible task to make a series of color 
 chips on which may be found any desired color. The inten- 
 tion is not, however, to show every desired color, but to give 
 a large number of colors, all bearing a relationship to each 
 other and in the form of progression, so that if a sample can- 
 not be matched on the chart it can be stated as lying between 
 two adjacent colors in the system. Most of these color charts 
 contain in the neighborhood of 1000 colors. | 
 
 The authors of these systems have accepted certain theories 
 of color arrangement and have made definite rules which have 
 been followed throughout the charts. Following is a brief 
 description and discussion of several of the more widely 
 known of these systems which the writers have studied. 
 
 Many of the charts described are very difficult to obtain and 
 quite expensive. All of them, with one exception (Chevreul’s), 
 may be seen at the Library of Congress in Washington. 
 
 Maerz and Paul ‘‘Dictionary of Color.’’—A. Maerz and M. 
 Rea Paul have recently published a Dictionary of Color which 
 is intended as a reference for those who seek to relate colors 
 
Color Systems, Colorimeters, Etc. 219 
 
 with the names by which they are commonly identified. The 
 book contains the most extensive range of colors as yet pub- 
 lished, together with a list of all recorded color names in use 
 up to this time in the English language. This dictionary pre- 
 sents more than 6000 colors, ranging from colors approaching 
 white to colors approaching black through practically every 
 eradation of hue, saturation and brightness. 
 
 This book is not intended to introduce any new type of color 
 system nor offer color names that have not already appeared 
 in print. The language of color as recorded in this dictionary 
 is, generally speaking, the expression of matured and prac- 
 tised usage. The ideal has been to produce a complete work 
 of reference in which may be found the name of every color, 
 and a sample of it, that has ever attained record in the English 
 language. , 
 
 It further presents a table showing the frequency of use of 
 the principal color names, a comparison table showing the 
 principal color names in several languages, and the spectro- 
 photometric measurements of various colors. 
 
 Another interesting feature is the secondary index, which 
 groups all synonymous names under a single main name. 
 
 Just as the English Dictionary records words and their 
 meanings acording to their accepted usage, this Color Diction- 
 ary is arecord of color words and the particular color sensa- 
 tions they identify, as established by consensus of opinion. 
 The system of color arrangement employed makes it easy to 
 find any named color and to readily choose an unnamed color 
 for a given purpose in the textile or paint industry. 
 
 This work is not, in any sense, an arbitrary establishment 
 of new standards, but is a co-ordination of the best thought 
 and work which has been published up to this time on the 
 subject of color. 
 
 Munsell System.—Mr. A. H. Munsell published in 1905 a 
 book entitled ‘‘A Color Notation,’’ and later a ‘‘Color Atlas”’ 
 based on the system outlined in his book. The book outlines 
 the system of arranging colors according to the three attri- 
 butes, Hue, Value and Chroma, and the Color Atlas contains 
 color chips arranged in the order given in the system. A brief 
 description of the system, which is considered to be perhaps 
 the best of a number of similar systems, follows. 
 
220 Color Systems, Colorimeters, Etc. 
 aan reer errr 
 
 Munsell defines the words Hue, Value and Chroma as fol- 
 lows: . 
 
 Hue.—Specifically and technically, distinctive quality of 
 
 coloring in an object or on a surface; the respect in which 
 
 red, yellow, green, blue, etc., differ from one another; that. 
 
 in which colors of equal luminosity and chroma may differ. 
 
 Value.—In painting and the allied arts, relation of one 
 object, part or atmospheric plane of a picture to others, 
 with reference to light and shade, the idea of hue being ab- 
 stracted. . ; 
 
 Chroma.—The degree of departure of a color sensation 
 from that of white or gray; the intensity of a distinctive 
 hue; color intensity. : 
 
 FIGURE 81 
 
 Theoretically every color finds its place on a color tree tak- 
 ing the shape, more or less, of a cylinder placed on its base 
 (Fig. 81). A band is traced around the equator and divided 
 into ten equal spaces which are lettered R, red, YR, yellow 
 red; Y, yellow; GY, green yellow; G, green; BG, blue green; 
 B, blue; PB, purple blue; P, purple; RP, red purple. The 
 spaces between the above divisions are divided into five equal 
 parts, thus making space for fifty different hues around the 
 equator of the tree. 
 
 The vertical axis of the tree is divided into 10 parts from 0 
 (black) at the base to 10 (white) at the top, thus giving the 
 dimension for the measurement of value. 
 
Color Systems, Colorimeters, Etc. 221 
 
 The third attribute of a color, the Chroma, is shown on the 
 tree by the length of radials from the center axis. ‘These ra- 
 dials are divided into 10 parts, starting with 0 at the axis. 
 
 To describe a color in the terms of Munsell’s system, the hue 
 is noted as one of the ten symbols R, YR, Y, GY, G, BG, B, PB, 
 P, RP. Value is shown by a small figure to the right of the 
 symbol and above, while Chroma is shown by a small figure 
 
 to the right and below, as, for example, Be The color rep- 
 
 resented by the figure just given would be ared. The value 5 
 being equidistant between 0 and 10 indicates that the color 
 lies equidistant in value between black and white. The Chro- 
 ma 9 indicates that the intensity of the color is very close to 
 the most intense color of the hue noted. 
 
 The Munsell Atlas—The Munsell Color Atlas consists of 15 
 eharts on which are shown 882 variations of the ten principle 
 hues given previously as RP, P, PB, B, BG, G, GY, Y, YR, R. 
 
 The first chart (H) gives these principal hues across the 
 page with a range of value for each one down the page. The 
 second chart (V) gives the range of value between White at 
 the top and Black at the bottom. The third chart (C) shows 
 the range of Chroma for several hues plotted at the various 
 positions on the vertical value scale. 7 
 
 The next five charts, (R) showing red and its complement 
 blue green; (Y) showing yellow and its complement purple 
 blue; (G) showing green and its complement red purple; (B) 
 showing blue and its complement yellow red; (P) showing 
 purple and its complement yellow green; consist of Value plot- 
 ted vertically and Chroma plotted horizontally. 
 
 The last seven charts consist of plotting the Hue and the 
 Chroma when the value is a constant in each case. 
 
 Chart (20), V = 2; (30), V = 3, (40), V = 4; (50), V = 9; 
 (60), V — 6; (70), V = 7; (80), V = 8. 
 
 The number of the chart was originally planned to desig- 
 nate the percentage of incident light reflected by the samples. 
 The squares of the Munsell values are proportional to the re- 
 flection of sunlight. 
 
 The Ridgway System.*—Mr. Robert Ridgway published in 
 1912 a color chart containing 1,115 named colors, based on the 
 
 *Color Standards and Nomenclature. Robert Ridgway. 
 
Zee Color Systems, Colorimeters, Etc. 
 a nt 
 solar spectrum, with its six fundamental colors and intermedi- 
 ate hues. He selected 36 fundamental hues, stated as the 
 greatest practical number for the pictorial representation of 
 the colors in their various modifications. The chart may be 
 divided into six main divisions. The first division shows the 
 36 fundamental hues, each with a seale of three tints and three 
 shades, the percentage of white for the tints being respectively 
 9.5 per cent, 22.5 per cent, and 45 per cent, while the percent- 
 age of black for the shades is 45 per cent, 70.5 per cent, and 
 87.5 per cent. The five remaining divisions show these same 
 36 hues, together with their tints and shades, displayed in ex- 
 actly the same manner as in the first division, the difference 
 being that all the colors in these last five divisions are dulled 
 by the admixture of a neutral gray. The amounts of neutral 
 gray are, for the divisions following in order, 32 per cent, 58 
 per cent, 77 per cent, 90 per cent, and 95.5 per cent respec- 
 tively. 
 
 Each of the colors shown has been given a name and also a 
 number. These numbers are arranged in the following man- 
 ner: In the first division the 36 fundamental hues are num- 
 bered 1, 3, 5, 7, etc., up to 71, intervals being left so that colors 
 which do not appear on the chart may be given a number. 
 Instead of stating that a color lies between 3 and 5, for exam- 
 ple, it would be given the number 4. The tints are lettered 
 b, d, and f, and the shades i,k, and m, intervals again being 
 left for tints or shades intermediate between those on the chart. 
 In the following divisions the notation is exactly the same as 
 in the first division, with the exception that for the second 
 division a is placed after the number of the color; for the 
 third ”, fourth ’, and for the fifth ’””. To illustrate the method 
 of numbering, take, for example, the color given the notation 
 66” e. This would be found in the third division of the chart, 
 therefore having 58 per cent of neutral gray added to the cor- 
 responding color of the first division. | 
 
 It would be an intermediate hue between the two marked 
 65” and 67”. 
 
 It would be an intermediate tint between the marked d and 
 the one marked f. 
 
 Wilkinson’s Color-Sound System.—Charles Henry Wilkin- 
 son published a color chart in 1891, in which a comparison is 
 drawn between the variations in color and the variations in: 
 
Color Systems, Colorimeters, Etc. 223 
 
 sound. The colors of the prism, Red, Orange, Yellow, Green, 
 Blue, Indigo, and Violet, are given the musical notations C, 
 D, E. F, G, A, B, respectively. This number is increased to 12, 
 as in the musical scale, by the addition of sharps and flats, 
 making the complete color octave the same as the musical oc- 
 tave. 
 
 The system is divided into 19 octaves graduated from 1 
 which contains 1 part black to 7 parts of color, through 9 
 which contains only the pure color with no admixture of black 
 or white, to 19 which contains 255 parts white to 1 part pure 
 eolor. 
 
 The above outlined system is maintained throughout the 
 following 24 charts of ‘‘Ranges.’’ Each range is made up of 
 three colors placed together in a chord, for example: Range 1, 
 C, Kh», G; Range 2, C, E, G; Range 3, Ct, E, G#, ete. 
 
 Twenty-four different combinations, varying from white 
 to black in 19 octaves, compose each range; for example, Range 
 1, composed of the three colors C, EH’, G, is subdivided into 24 
 combinations of the colors, C, E® and G, such as C, CG, CGC, 
 CH°GC, ete. Each of these combinations is followed through 
 19 octaves from black to white. 
 
 Wilkinson’s system contains over 10,500 color chips, some 
 of which are duplications of the same colors. These chips are 
 arranged in an order which necessitates looking practically 
 through the entire system for a match. The fact that the col- 
 ors of the prism are given unfamiliar names only adds to the 
 confusion begun by the unwieldy number of colors dealt with. 
 No attempt was made to match samples against this system, 
 but it is thought that probably, due to the large number of 
 colors, a few more samples may be matched. The general 
 criticisms of color charts apply to Wilkinson’s system. 
 
 Societe Francaise des Chrysanthemistes Repertoire de Cou- 
 leurs.—The French Chrysanthemum Society a number of years 
 ago published a color chart called the ‘‘Repertoire de Cou- 
 leurs,’’ designed by Dauthenay and several others. This chart 
 consists of approximately 1,400 colors arranged in twelve se- 
 ries as follows: 1, Whites and tinted whites; 2, Yellows; 3, 
 Oranges; 4, Reds; 5, Roses; 6, Purples; 7, Violets; 8, Blues; 9, 
 Greens; 10, Browns and Ochres; 11, Maroons; and 12, Blacks 
 
224 Color Systems, Colorimeters, Etc. 
 
 and Grays. Each series contains a varying number of plates 
 and each plate shows four variations of the same hue. 
 
 This chart is simply a display of various colors without any 
 definite order, except the division into series. It is apparently 
 specialized for the purpose for which it is intended, that of 
 defining the colors of flowers and plants, as there are great 
 numbers of greens, browns, reds, and roses. A number of 
 plates show the colors of copper, bronze, silver, and gold which 
 are not usually shown in such charts. 
 
 Chevreul’s Color Chart.*—Michel Eugene Chevreul devised 
 a color chart containing ten chromatic circles. Hach circle is 
 composed of 72 colors arranged in the order Red, Red Orange, 
 Orange, Orange Yellow, Yellow, Yellow Green, Green, Green 
 Blue, Blue, Blue Violet, Violet, Violet Red. The first circle 
 or chart contains what are onlied the purest and most intense 
 colors, and each of the succeeding circles or charts contains 
 these same colors to which has been added an ever-increasing 
 definite amount of black. 
 
 Following these are other charts arranged in bands each 
 composed of 22 steps ranging from 0 White, through the vari- 
 ous changes in one of the 72 original colors, to 21 Black. The 
 color of the original color circle in each ease is placed at 10. 
 
 Charts of Moses Harris.—In 1811, nearly thirty years after 
 the death of Moses Harris, were published two charts of colors 
 based on his theories. These charts represent one of the earli- 
 est, if not the first, attempt at showing an arrangement of a 
 oe number of colors. 
 
 The first plate, known as the Prismatic Chaee contains 18 
 colors occurring in the spectrum, arranged ina circle. ‘These 
 18 colors are based on the ‘‘three grand primitive colors, Red, 
 Blue, and Yellow, and are placed in the following order around 
 the circle: Red, Orange Red, Red Orange, Orange, Yellow Or- 
 ange, Orange Yellow, Yellow, Green Yellow, Yellow Green, 
 Green, Blue Green, Green Blue, Blue, Purple Blue, Blue Pur- 
 ple, Purple, Red Purple, Purple Red. The whole circle is di- 
 vided into 20 concentric circles or ‘‘degrees of power,’’ vary- 
 ing from 20, the deepest and strongest color at the inside, to 0, 
 the weakest at the outside. 
 
 * An early attempt and of little practical use at the present time. 
 
Color Systems, Colorimeters, Etc. VA) 
 
 The arrangement of the second and last plate or ‘‘Compound 
 Chart’’ is exactly the same as in the Prismatic Chart, the dif- 
 ference being that it is based on the three mediate colors, Or- 
 ange, Green, and Purple. The 18 colors in this case are placed 
 around the circle in the following order: Orange, Olive Orange, 
 Orange Olive, Olive, Green Olive, Olive Green, Green, Slate 
 Green, Green Slate, Slate, Purple Slate, Slate Purple, Purple, 
 Brown Purple, Purple Brown, Brown, Orange Brown, Brown 
 Orange. 
 
 Harris stated that another chart might be made based on 
 Olive, Slate, and Brown, but that any further division would 
 give colors between which there could be little differentiation. 
 
 These charts are of no practical use at the present time, but 
 are an example of the first attempts to display an orderly ar- 
 rangement of colors. 
 
 In diseussing color charts, the main objection that can be 
 found with the majority is the fact that they do not contain a 
 sufficient number of colors to enable a large number of samples 
 to be matched. 
 
 The colors used in the manufacture of these charts are as 
 fast as it is possible to make them, but in a number of cases 
 the pigments used in painting the chips are sensitive to pro- 
 longed exposure to light. It is probable that these charts 
 change slightly in some particulars over a period of a few 
 years. 
 
 In making such a large number of colors as are used in the 
 charts, slight errors creep in, due to a variation in the pig- 
 ments, ete., used. Unless all the colors used are tested with 
 great care, no two charts will be exactly alike in every particu- 
 lar. 
 
 With regard to the use of these charts, several factors are 
 of importance: | 
 
 In specifying a color on a certain chart, the character of 
 illumination must also be stated in understandable terms. 
 Colors appear very differently under different sources of illu- 
 mination. What would seem to be a match under a certain 
 illumination might be considerably off under another light of 
 slightly different wave length. 
 
 When a color is being matched, it must not be influenced 
 by other colors. Colors when placed in juxtaposition to 
 
226 Color Systems, Colorimeters, Etc. 
 
 other colors are often so influenced as to assume an entirely 
 different appearance. 
 
 The majority of color charts are in flat colors, which in- 
 creases the difficulty of matching glossy paint chips with them. 
 It is necessary that both the sample and chart shall present 
 the same type of surface to the eye, in order that a perfect 
 match be made. ‘This can easily be observed by comparing the 
 shiny and the flat surfaces of a piece of silk. 
 
 It will be seen from the above that a color cannot be defin- 
 itely specified by giving it a reference number on a certain 
 color chart, unless the same chart is used by the same operator 
 and at the same illumination each time. Colors lying between 
 two colors on the chart will be assigned to different positions 
 by various operators. In the 4th, 5th, and 6th divisions of 
 the Ridgway system, for example, several numbers for inter- 
 mediate colors are left blank between two adjacent colors. In 
 this case different operators would assign widely different 
 numbers to colors not appearing on the chart. 
 
 Observers who are color blind, or partially so, believe that 
 they can match samples against the charts, but the results ob- 
 tained by them are incorrect. 
 
 (‘OLORIMETERS 
 
 Numerous types of colorimeters have been devised for the 
 measurement of color with optical aid. Colorimeters define 
 the sensation which the color produces on the eye and see only 
 that which the eye sees—that is, when two sample colors ap- 
 pear the same under one illumination they will appear to be 
 same in the colorimeter. But if these same two samples should 
 appear to be different under another illumination then they 
 will appear to be different to the colorimeter, if the latter il- 
 lumination is used. In other words, the fact that they appear 
 alike to the colorimeter is not conclusive proof that they will 
 appear alike under all conditions. Two colors may match ex- 
 actly in the instrument under white light and yet be entirely 
 different under common electric-light illumination. 
 
 Colorimeters have the advantage that results may be rapidly 
 obtained by their use. A measurement consists solely of set- 
 ting three or four calibrated adjustments. In order to repro- 
 duce the color found at any future time, it is only necessary 
 to set the instrument in the same manner as before. In other 
 
Color Systems, Colorimeters, Etc. 227 
 
 words, if a standard color be measured on the instrument, the 
 same setting can be made at a future time and samples com- 
 pared with this setting, thus providing an unchanging ref- 
 erence standard. 
 
 Results agreeing very closely (within the range of the in- 
 strument) may be obtained by persons having normal vision, 
 but since the operation of colorimeters depends entirely upon 
 the judgment of a match by a particular observer, color blind 
 or even partially color blind persons are unable to take read- 
 ings. 
 
 Colorimeters may be subdivided under two headings. The 
 monochromatic type, of which the Nutting Colorimeter is an 
 example, and the trichromatic, of which the Jones, Ives, Baw- 
 tree, Lovibond, Guild, ete., are examples. 
 
 The Monochromatic Colorimeter.—Defines the color under 
 examination in terms of dominant hue and per cent of white 
 hight. Dominant hue is given in terms of wave length. The 
 visible spectrum may be divided in a number of parts from 
 wave length 440 to wave length 700. The dominant hue of a 
 color is the wave length of the spectrum color which most 
 nearly approaches the sample under examination. 
 
 The Trichromatic Colorimeter.—Defines a color in terms of 
 three arbitrary primaries, Red, Green, and Blue. These pri- 
 maries vary with the different types of instruments. The 
 colors are provided by dyed gelatine wedges, transparent glass 
 filters, ete. This class may be further subdivided into two 
 main types: those which operate on the Additive Principle 
 and those which operate on the Subtractive Principle. 
 
 Additive Principle-—Three arbitrary primaries are taken, 
 Red, Green, and Blue, with a device for varying the intensity 
 of each. The color of the sample is reproduced by varying 
 these intensities. 
 
 Subtractive Principle——The light passes through variable 
 color filters, subtracting a greater or less amount of a particu- 
 lar color. It is not possible to introduce variations of hue by 
 changing the aperture as in additive instruments. This vari- 
 ation in hue is obtained by changing the thickness of colored 
 filters. 
 
 When a trichromatic colorimeter is employed for analysis 
 or synthesis, the color sensation in terms of true red, true 
 
228 Color Systems, Colorimeters, Ete. 
 
 green, and true blue components depends entirely upon an 
 accurate knowledge of the sensation values of the three filters 
 used in the instrument. When these sensation values are 
 known, the results obtained by the instrument may be trans- 
 posed by calculation into true value. Further, when these 
 true values are known, it is then possible to determine by an- 
 other series of calculations the hue, saturation, and brilliance 
 of a sample. 
 
 The Nutting Colorimeter.*—The Nutting Colorimeter is a 
 monochromatic analyzer which has wide range and 1s of high 
 precision. A monochromatic analyzer is an instrument which 
 defines a color in terms of the dominant hue or wave length of 
 the color and the percentage of white light. 
 
 The instrument consists of a spectral collimator to admit 
 light to be spread into a spectrum by a constant deviation type 
 dispersing prism. This prism 1s rotated by a fine screw at- 
 tached to a drum on which the wave length of the light re- 
 flected by the sample may be read directly when a match has 
 been obtained. The intensity of the portion of the spectrum 
 under examination may be varied by rotating one of the polar-— 
 izing prisms interposed in the path of the light. 
 
 Two more collimators, one to admit the standard white light 
 and the other to admit the light from the sample, are placed 
 so that the light from the former strikes a mirror wheel con- 
 sisting of two quarters plain glass and two quarters mirror, 
 and the light from the latter strikes a prism which acts as a 
 mirror, simply changing the direction. Both these eollimat- 
 ors are fitted with polarizing prisms for varying the intensity 
 of the light admitted. The whole is so arranged that all three 
 paths of light converge in the eyepiece. The mirror wheel re- 
 ferred to above is stationary in a clear glass position when the 
 color match is being made, but is rotated as a flicker photo- 
 meter when the intensity is matched. 
 
 The sensitiveness of the instrument is that of the observer’s 
 eye. The uncertainty in the wave length of the dominant hue 
 is about 1 or 2 millimicrons, except in the extreme red and vio- 
 let, and for colors very near neutral gray and for very dark 
 colors. 
 
 The instrument is a very expensive one. 
 
 * Bull. Bureau of Standards, Vol. 9, No. 1. 
 
Color Systems, Colorimeters, Etc. 229 
 
 The process and calculations are more complex than in some 
 of the more modern instruments. 
 
 Bawtree Colorimeter.*—This instrument, which was recently 
 designed by a member of the British Oil and Colour Chem- 
 ists’ Association, consists of two light-diffusing systems which 
 share equally the illumination from the source of hight em- 
 ployed, preferably a metal filament electric lamp. In one sys- 
 tem is placed a shutter operated by a pointer and scale divided 
 into 100 parts. In the other system are three shutters of the 
 same kind, covering sheets of transparent medium of accur- 
 ately standardized primary color of such strengths that the 
 three when each shutter is opened an equal amount, will pro- 
 duce white light. When the three color shutters are fully open, 
 the white light matches that from the other.side, when its one 
 shutter stands at 10. The light issues on the two sides from 
 - openings two inches square, separated only by the thickness 
 of a piece of tin. Now, if a magenta painted card be placed 
 behind the white opening and a piece of standardized white 
 material provided be placed behind the opening correspond- 
 ing to the color slides, it may be found, for example, that to 
 match it the scales read: Red, 100; Green, 10; Blue, 60. This 
 tells at once the actual percentages of colored light which the 
 material reflects, and also shows that apart from its color it 
 reflects 10 per cent of white light. 
 
 Lovibond Tintometer.—In 1886 Mr. J. W. Lovibond made 
 public the results of his research on color measurement. From 
 that time until 1920, when the finally approved tintometer ap- 
 peared on the market, many changes were made. Usually the 
 Lovibond tintometer, for use by the paint trade, is associated 
 with color readings on liquids such as varnishes, oils, etc., but 
 by the use of attachments furnished by the manufacturers col- 
 ored opaque surfaces may be measured. 
 
 The instrument consists of a viewing box with no optical ar- 
 rangements whatsoever. In one side is placed the sample to 
 be tested, and in the other are placed standardized colored 
 glasses until a color match has been obtained. 
 
 A complete set of color glasses or standards consists of 155 
 glasses for each of three scales or colors, Crimson, Yellow- 
 
 * Jour. Oil and Colour Chemists’ Assn., No. 11, 1919, pp. 68-70. Description 
 and criticism of Bawtree Colorimeter complete. 
 
230 Color Systems, Colorimeters, Etc. 
 
 Green, and Blue, making a total of 465 glasses. Hach scale 
 consists of glass slides all of the same color but varying in 
 thickness in definite steps from .01 to 20.0 tint units. These 
 steps are so arranged that three glasses are all that are re- 
 quired to obtain any setting for one color. Sufficient glasses 
 of all three colors are inserted to match the sample. All the 
 glasses used in making a match must be noted together with 
 their colors. If four glasses of one color totaling a certain 
 number of tint units are used, the resultant color will be darker 
 than if three glasses totaling the same number of tints are 
 used. 
 
 A complete set of glasses are expensive. They are easily 
 broken. 
 
 Hach individual glass must be noted, as a different combina- 
 tion of glasses will give a different result. 
 
 Notr.—A Circular on the Accuracy of the Lovibond Set at the U. 8. Bureau 
 of Standards has recently been published by the Bureau. 
 
 The sample is difficult to compare with the glasses, as there 
 are no optical arrangements for viewing both, side by side. 
 
 Ives Color Meter.*—In 1907, Frederic E. Ives perfected a 
 ‘‘Color Meter’’ based on the same principles as Clerk Max- 
 well’s Color Box. This color meter compares the light from 
 a sample with the light coming from an adjustable mixture of 
 the three primaries, Red, Green, and Blue-Violet. The instru- 
 ment itself is divided in two halves, and white light or the 
 light from the sample to be measured is admitted through the 
 right half passing to the right half of the eyepiece. The light 
 on the left half comes from three lateral slits, Red, Green, and 
 Blue-Violet, and passes through a diffraction grating, in place 
 of prisms in Maxwell’s box, which converges all three beams 
 of light in the left half of the eyepiece. A color match in both 
 halves of the field is obtained by adjusting these slits by means 
 of a micrometer screw calibrated from 0 to 100. The position 
 of each slit shown by a pointer is noted and the color is defined, 
 as, Red, 40; Green, 20; Blue-Violet, 60, for example. 
 
 The percentage of black may be found by subtracting the 
 largest reading obtained from 100, and also the percentage of 
 white is represented by the smallest reading obtained, for ex- 
 ample above, Black = 100— 60 = 40, White = 20. 
 
 * Journal Franklin Institute, Vol. 164, 1907, p. 47. 
 
Color Systems, Colorimeters, Etc. 231 
 
 The instrument must be pointed at a white object or must be 
 illuminated by white light, otherwise comparisons would not 
 be true under differing illumination. In order to use the in- 
 strument persons must have normal vision. 
 
 The Hess-Ives Tint Photometer.—The underlying principle 
 of the Hess-Ives Tint Photometer is somewhat similar to the 
 spectrophotometer. The sample to be matched is compared 
 with a block of magnesium carbonate, which is assumed at the 
 present time to be the whitest known substance. The illumina- 
 tion is furnished by a daylight electric bulb. The light from 
 this source is reflected from the sample to be tested and from 
 the block of magnesium carbonate, which are placed side by 
 side on a stand, into the instrument by a mirror. The instru- 
 ment is so arranged that the light reflected from the magne- 
 sium carbonate block illuminates one-half of the field, while the 
 light reflected from the sample illuminates the other. A mix- 
 ing wheel revolves in the path of the light, insuring the even 
 distribution of light over both halves of the field, which is di- 
 vided vertically instead of horizontally, as is usually the cus- 
 tom. When the instrument is in use, a calibrated screw must 
 be adjusted until both halves of the field are illuminated 
 equally. | 
 
 After these adjustments have been made, a red color screen 
 is put in position. A shutter, operated by a calibrated lever, 
 regulates the light transmitted to the eyepiece by the mag- 
 nesium carbonate block. This lever is now moved back and 
 forth until a match in both halves of the field has been ob- 
 tained. 
 
 When the match is obtained, the position of this lever is 
 noted, as, for example, Red, 60. The same procedure is then 
 followed with a Green and with a Blue-Violet screen. The 
 full notation is then made, for example, as, Red, 60; Green, 80; 
 Blue-Violet, 30, the sample being a green containing some red, 
 and considerably less blue-violet. If all these three figures 
 were proportionately lowered, the sample would have a pro- 
 portionately increased admixture of black, and therefore would 
 be darker. These results may be shown graphically on cross- 
 section paper. The points are plotted on three vertical lines 
 marked Red, Green, and Blue-Violet, divided into 100 parts 
 with 0 at the bottom and 100 at the top. Very little study 
 
232 Color Systems, Colorimeters, Etc. 
 SN aaa 
 enables one to more or less picture a color by a reference to 
 this graphic representation. 
 
 The results given by this instrument on one sample (pea 
 ereen) are shown on page 249. These results have been plot- 
 ted as a three-point curve. 
 
 From the results obtained on the instrument the luminosity 
 value and also the admixture of black may be calculated. <A 
 luminosity factor has been determined for each of the three 
 colors. These are, Red, 0.19; Green, 0.71; and Blue-Violet, 
 0.10. To calculate the luminosity, the red reading of the sam- 
 ple is multiplied by the red factor, the green by the green fac- 
 tor, and the blue-violet by the blue-violet factor. These three 
 derived values are then added and the results are the total 
 luminosity. Perfect luminosity is 100 per cent, consequently 
 the admixture of black is the difference between the total In- 
 minosity and 100 per cent. 
 
 Comments on Hess-Ives Tint Photometer.—The results 
 which the writers have obtained on the Hess-Ives Tint Photo- 
 meter indicate that the instrument will differentiate between 
 two colors which are very similar in appearance to the naked 
 eye. This will be seen by reference to the charts of colors 1, 
 4 and 5 and also 2 and 3. These colors are different to the 
 eye and the instrument points out that difference. 
 
 It is felt that there is a possibility of finding at some time 
 two colors, which are entirely different to the naked eye, such 
 as ared and a green, and yet give the same results when meas- 
 ured. However, this possibility seems rather remote. 
 
 A comparison of the performance of two Hess-Ives Tint Pho- 
 tometers cannot be given at this time due to the lack of suffi- 
 cient data. The manufacturers state, however, that two in- 
 struments agree very closely. This agreement depends upon 
 the exact duplication of the colored glass filters and also the 
 block of magnesium carbonate. 
 
 The instrument appears to be rather flimsily constructed 
 and might not stand up under hard usage. This, however, 
 is a difficulty which could be easily remedied. , 
 
 The Eastman Universal Colorimeter.*—The Hastman Uni- 
 versal Colorimeter was designed recently by Mr. Loyd A. 
 
 *Jour. Optical Soc. Am., 4; 420 (1920). 
 
 Bees ger 0S ab diet 
 
 ey eS 
 
Color Systems, Colorimeters, Etc. 233 
 Jones, of the Fastman Kodak Co. During the World War 
 it was used to a large extent in determining the color of the 
 horizon and of the sea under various conditions. These results 
 were then used in the tinting and shading of camouflage paints 
 to be used on vessels, ete. 
 
 The instrument has numerous attachments each for a par- 
 ticular use, such as the measurement of the color of liquids, 
 dyed gelatines and glasses, another for reflecting surfaces, 
 another for light-colored liquids, ete. 
 
 “The colorimeter* operates on the subtractive principle, 
 and any desired color is obtained in the comparison field by 
 
 FIGURE 82 
 
 THE EASTMAN UNIVERSAL COLORIMETER. 
 
 the subtraction of certain parts from the white light used for 
 the illumination of the comparison field. This subtraction 
 is accomplished by the use of dyed gelatine wedges. These 
 wedges are made by coating glass plates with dyed gelatine, 
 so that the thickness of the gelatine layer varies from zero 
 at one end to a maximum at the other. The three color addi- 
 tive primaries are red, green, and blue, and when light of these 
 three colors is combined white light is obtained. By using 
 three wedges, each of which absorbs one of the three additive 
 
 * Instructions for operating the Eastman Universal Colorimeter. 
 
234 Color Systems, Colorimeters, Etc. 
 
 primaries, any desired amount of each primary may be sub- 
 tracted from the white light. 
 
 The method of obtaining any desired color by the subtrac- 
 tive method may be explained by reference to Fig. 83. The 
 three squares in the top line of the diagram represent red, 
 green, and blue components of white light. Now, if by some 
 means the blue component is absorbed, we have left the red 
 and green components which yield yellow. That is, if the blue 
 component be removed from white light the remaining hight 
 will appear yellow, or, in the terminology of the subtractive 
 method, minus blue. Likewise, as indicated in the third line 
 of the diagram, if green is absorbed, the blue and red com- 
 ponents remain, giving magenta or minus green. While if 
 the red component be absorbed, as indicated in the fourth 
 line of the diagram, the blue and green components remain, 
 giving a blue green or minus red. This illustrates the nature 
 of the three color subtractive primaries, namely, minus blue, 
 minus green, and minus red. 
 
 Blue Green Red 
 (Removed ) Green Red 24 
 (—Blue) Yellow 
 Blue (Removed) Red (—Green) Magenta 
 Blue Green (Removed) (—Red) Blue-Green 
 
 FIGURE 83 
 
 The action of the (—Blue) wedge in the colorimeter is, 
 therefore, illustrated by the second line of the diagram in 
 Fig. 83. When this wedge is set at zero, that is, completely 
 withdrawn from the path of light illuminating the compari- 
 son field, no absorption takes place, but as it is introduced into 
 the path of the light, blue light is subtracted from the white 
 light to a greater and greater extent as the thickness of the 
 gelatine coating increases. When this wedge is introduced 
 so that the point of maximum thickness is in the path of the 
 white light, a condition similar to that indicated in the second 
 line of the diagram exists, and practically all of the blue light 
 present in the white light of the comparison field is absorbed, 
 leaving the comparison field illuminated by (—Blue) or yel- 
 low light. The conditions existing when the (—Green) and 
 
Color Systems, Colorimeters, Etc. 235 
 
 (—Red) wedges are inserted are shown in the third and fourth 
 lines of the diagram. 
 
 Blue Removed Green Removed Red 
 Blue Green Removed Red Removed 
 Blue Removed Green Red Removed 
 FIGURE 84 
 
 It is evident that (Fig. 84) if the (—Blue) and (—Green) be 
 inserted simultaneously, the transmitted light will be red, 
 while if the (—Green) and (—Red) are used together, blue 
 will be obtained, and as a third combination if the (—Blue) 
 and (—Red) be used together green light only will be trans- 
 mitted. ’’ 
 
 The readings which are given in the tables and from which 
 the curves are drawn are reported in terms of —Green, 
 —Blue, and —Red. It will be seen that if the sample is Green, 
 no green should be subtracted, therefore the —Green wedge 
 should remain in the zero position and the reading in this 
 column will be zero. When the sample is blue, the —Blue 
 wedge is placed at zero and the reading is zero, and when the 
 sample is red the —Red wedge is at zero and the reading is 
 zero. In the case of colors which do not come under the head- 
 ing of red, green or blue, one of the three wedges must remain 
 at zero, which is determined by one of the component colors 
 which go to make up the color of the sample. For example, 
 in the case of some brown samples the —Red wedge remains 
 at zero and the reading in the —Red column is zero. 
 
 The readings in the column marked Neutral represent the 
 amount of neutral gray which it is necessary to add to match 
 the intensity of the sample. 
 
 The operation of the colorimeter is simple. 
 
 The electric current furnished by a 3 cell 100 ampere-hour 
 storage battery is first properly adjusted, giving the correct 
 illumination which is obtained by checking against a standard 
 illumination furnished with the machine. After the lamps 
 have been lighted, the field presented to the eye is a circle 
 divided in half by a horizontal line. The lower half of the 
 field represents the color reflected from the sample and the 
 
236 Color Systems, Colorimeters, Etc. 
 
 upper half is the color produced by introducing the various 
 wedges. In order to take a reading, it 1s necessary to intro- 
 duce the two color wedges decided upon, until a color mateh 
 
 EastMAN UNIVERSAL COLORIMETER 
 PoLAR CoO-ORDINATE CHART 
 
 FIGuRE 85 
 
 The color is denoted by the point on the vector in each case. The points 
 
 plotted by the writers are based on the results of the Eastman Kodak Co. 
 at their laboratory. 
 
 is obtained in the upper and lower halves of the circle. The 
 intensity is controlled meanwhile with the neutral wedge. 
 When a good match has been obtained both in color and in- 
 tensity, the position of all the wedges is recorded. Several 
 
 te tS 
 
Color Systems, Colorimeters, Etc. Dal 
 
 readings are made and an average taken, as sufficient accuracy 
 cannot be obtained with one setting. 
 
 Representation of the Results of the Eastman Colorimeter. 
 —The readings obtained on the Kastman Universal Colori- 
 meter on one sample of (pea green) are graphically shown in 
 the form of a curve on page 249. This has been done solely 
 for the purpose of comparing more easily the results obtained 
 by two observers on two different instruments. 
 
 Correspondence with Mr. L. A. Jones, of the Hastman 
 Kodak Company, has brought out the fact that the results 
 obtained on the instrument may be calculated to arbitrary hue 
 and saturation factors which can be presented on a polar co- 
 ordinate chart. The three subtractive primaries, green, blue, 
 and red, are placed at 0°, 120°, and 240° respectively, while 
 the three additive primaries, red, green, and blue, are placed 
 at 60°, 180°, and 300° respectively. 
 
 The position of a point is represented by two values; X, 
 the length of the vector, that is, the line drawn from the center 
 to the point in question; and ®, the angle between this vector 
 and the reference axis of the system, that is, the line from 
 the center of the circle to zero position on the circumference. 
 A variation in ® may be considered as equivalent to a variation 
 in hue, while a variation in X designates a variation in the 
 saturation factor. Since color requires a statement of three 
 factors for its complete specification, it is obviously impos- 
 sible in any single plan having but two dimensions to plot 
 graphically all three of these variable. A single plane dia- 
 eram such as this, therefore, is only adequate for the show- 
 ing of variations in the two factors, hue and saturation. The 
 method used for plotting the colorimeter readings in this co- 
 ordinate system is as follows: 
 
 Let G = the scale reading of minus green wedges. 
 Let B = the scale reading of minus blue wedges. 
 Let R = the scale reading of minus red wedges. 
 Let N = the scale reading of neutral wedges. 
 
 Since any color can be matched by the use of two of the colored 
 wedges in combination with the neutral, we have three differ- 
 
238 Color Systems, Colorimeters, Etc. 
 
 ent equations for finding the value of ® from the seale read- 
 ings. They are as follows: 
 When the minus green and minus blue wedges are used 
 
 pass B 20 
 ® Ge Make 
 When the minus blue and red wedges are used 
 R 
 a eee ye . 
 =H X 120 + 120 | 
 When the minus green and minus red wedges are used 
 
 The values of ® computed according to these equations will 
 locate the hue of any sample, and a line drawn through the 
 center to the designated angle will be the locus of the point 
 which must be plotted to represent the hue and saturation 
 
 of the sample in the polar co-ordinate diagram. 
 
 The value of X is determined by taking the average of the 
 two colored wedge readings, thus, when the minus green and 
 minus blue wedges are used: 
 
 @-EB 
 Die: a2 
 and likewise for the other combination 
 ue aa 
 X=——9 
 or 
 G+R 
 nee =e 
 
 This will now locate the point which gives a definite idea as to 
 the hue and saturation of the color in question. 
 
 There is no definite relation between the angular values and 
 the wave lengths of the dominant hue. It should be empha- 
 sized that this system is not a method of converting the colori- 
 meter readings to the standard notation of the monochromatic 
 system. | 
 
 On pages 248 and 249 are shown specimen graphs on the 
 same green which have been plotted from readings on three 
 different instruments, according to this method in Fig. 85. 
 
 Comments on Eastman Universal Colorvmeter.—In discuss- 
 ing the Eastman Universal Colorimeter, one distinct advan- 
 tage over a spectrophotometer may be noted, namely, the 
 duplication of a standard color in the instrument at a future 
 time by making the corresponding setting of the wedges. It 
 
Color Systems, Colorimeters, Etc. 239 
 ee ..............__ 
 would be thought that once a standard color has been measured 
 on the instrument and the results recorded, any sample may 
 be compared with this standard by setting the instrument to 
 the recorded values of the standard. However, one difficulty 
 arises in this connection, for while it is theoretically true, it 
 fails to a slight extent in practice. The sample may be slightly 
 different from the standard to the naked eye and yet give 
 results on the instrument which are well within the limits of 
 experimental error. A comparison of the reading on Greens 
 #4 and #5 show this fact quite clearly. ‘The two colors are 
 quite different to the eye and yet the four lines in the graphic 
 representation of these two colors are noticeably interlaced, 
 showing that the results of one, due to experimental error or 
 to the slight difference in two instruments, might easily be 
 mistaken for the results of the other. 
 
 With a little practice colors may be matched quite readily 
 in the instrument. The manufacturers state that an exact 
 match cannot be made and that an average of several readings 
 must be taken. This is due, in a large measure, to eye fatigue. 
 When the colors in the instrument are observed for a short 
 time, the eye retains the color shown and does not react quickly 
 to the slight changes which are necessary in matching the 
 sample. This is particularly noticeable after using the instru- 
 ment for several hours, and for this reason it is thought that 
 the instrument should not be used uninterruptedly when a 
 large number of samples are to be measured. Results obtained 
 on the instrument by partially or totally color-blind persons 
 will not agree with those obtained by persons having normal 
 vision. Results depend entirely upon the observer’s judg- 
 ment of a color match. 
 
 Martin and Gamble* state that ‘‘several questions naturally 
 arise (with regard to a Wedge Colorimeter) connected with 
 the permanence and the possibility of producing wedges 
 identical in performance for similar instruments, for unless 
 various instruments will give identical arbitrary indications 
 of the same color the special calculations necessary to in- 
 terpret a measurement for any one instrument will certainly 
 inhibit its commercial use.’’ 
 
 The manufacturers state that the wedges used in the instru- 
 ment have been found to be constant as regards a change in 
 
 *Color and Methods of Color Reproduction. Martin & Gamble, p. 113. 
 
240 Color Systems, Colorimeters, Etc. 
 OS 
 eolor from the standard over a considerable period of time. 
 They report that one wedge which was exposed to direct sun- 
 light for over a month showed no appreciable change. 
 
 In comparing the check results of two instruments, it has 
 been observed that while certain portions of two blue wedges, 
 for example, will give absolute agreement, other portions of 
 the same two wedges will give slightly different results. 
 Slightly differing values will be obtained at the points where 
 the wedges differ slightly. No data is obtainable at present 
 which will show the maximum difference at a definite point in 
 a number of wedges of a certain color. It is thought that the 
 experimental error noted previously is due largely to this 
 difference in wedges at various fixed points. 
 
 Howland Comparative Color Photometer.*—The Howland 
 Comparative Color Photometer is basically a modern adapta- 
 tion of Maxwell’s principle of spinning dises. Mr. Howland 
 describes the Photometer as ‘‘a light, tight box with a slide 
 in the front having a small opening, through the aperture of 
 
 ea 
 
 1 
 
 Ay D> 
 
 which the operator sees the absolute black of the interior. It 
 contains a small high-speed motor with a shaft arranged for 
 clamping dises of thin cardboard which may be spun close 
 behind the opening. The motor is screened from view by a 
 second partition covered with black velvet, while a third screen 
 back of the motor aids in absorbing any light rays which might 
 otherwise find their way to the black velvet which covers the 
 back of the box on the inside.’’ By this method the back- 
 
 FIGURE 86 
 
 *Drugs, Oils and Paints, 32: 48 (1916) ; 33: 4384 (1918). 
 
Color Systems, Colorimeters, Etc. 241 
 
 eround is so completely screened that the effect on looking ae 
 the opening is one of absolute black. 
 
 The dises with which the sample is compared are cut as is 
 shown in Fig. 86. These are furnished in several colors as well 
 as white and are of all sizes from 0 to 100. The black is sup- 
 plied by the black of the interior of the box, showing between 
 the wedges as they revolve. The sample is then put on a small 
 dise over the standard ones and the whole revolved. When 
 the correct percentages of the standards have been chosen so 
 that the field appears uniform throughout, an equation is 
 drawn: 
 
 .Y 
 
 Ts 
 
 FIGURE 87 
 
 Color of sample = Various percentages of standards used 
 + (100 — total percentages) or black. 
 
 It has been determined that a sample is matched by 23 per 
 cent Red, 20 per cent Yellow, and 19 per cent White. There- 
 fore, Color of Sample = 23 per cent Red + 20 per cent Yellow 
 = os 19 per cent White + 
 
 100 — (23 + 20 + 19) or + 38 Black 
 
242 Color Systems, Colorimeters, Etc. 
 
 The hue, strength, and luminosity are then calculated. 
 
 The hue is calculated by reducing the colored areas to per- 
 centage: 
 234202 48 
 23 = 43 = .53 or 53, Red 
 20 + 43 = 47 or 47 Yellow 
 The strength is calculated by adding the colored areas 
 together : 
 23 + 20 = 48 
 The luminosity is caleulated by multiplying the colored 
 areas respectively by luminosity factors stated as: 
 Red, .27; Yellow, .85; Green, .25; Blue, .5 and adding the 
 white area. 
 
 98 OT See 
 20 X 85 = 17.00 
 White 19 
 
 Luminosity = 42.2 
 The color of the sample is now plotted on the diagram 
 (Fig. 87). A line is drawn from N at the center of the diagram 
 to a point on the R-Y line, 47 spaces from R and 93 spaces 
 from Y. Assuming that the point N is zero on the drawn in 
 line and its intersection with the R-Y line 100, the luminosity 
 
 42 ig now marked. This point indicates the color of the 
 
 sample. 
 SPECTROPHOTOMETERS 
 
 A spectrophotometer is an instrument by means of which a 
 colored sample may be compared with a block of Magnesium 
 Carbonate, which is assumed as the standard white. The 
 spectral reflection curve is plotted from the results, which 
 are given in percentage brilliance for all wave lengths through- 
 out the visible spectrum. 
 
 Previously in this paper the statement was made that colori- 
 meters define the sensation produced on the eye by a color. A 
 spectrophotometer defines the stimulus which incites that sen- 
 sation. If we take a color, which to our eyes gives the sensa- 
 tion of red, the colorimeter will define the red which we see 
 and nothing more. However, if we take this same red and ex- 
 amine it with a spectrophotometer we will obtain a series of 
 values, representing the various stimuli, which when com- 
 bined will produce the same red sensation as before. Itis due 
 to this fact that two colors having identical spectrophoto- 
 
 metric readings will be one and the same under all conditions — 
 
 wee 
 
Color Systems, Colorimeters, Etc. 243 
 
 of illumination. Ives* states that ‘‘the only unique specifica- 
 tion of a color is by means of its spectrophotometric analysis.’’ 
 
 Ives continues in the same article that ‘‘the objections to 
 the spectrophotometer for practical color measurements are 
 obvious. It is an expensive and delicate instrument. A large 
 number of measurements are necessary to specify a single 
 eolor. The color cannot be reproduced for study or compari- 
 son by setting the instrument to the measured values. The 
 results, plots of readings against wave lengths, mean little 
 except to a specially trained expert. On the other hand, there 
 is no ground for believing that satisfactory color measure- 
 ment will ever be done by anything except high-grade and 
 hence expensive apparatus or that really accurate color speci- 
 fications can be made simple.’’ 
 
 Color is produced by the vibration of a ray of light. This 
 vibration has been measured and the result has been termed 
 the wave length of a color. As this wave length is exceedingly 
 small, a very small unit of length must be chosen. The mill- 
 micron, mu, or one-millionth of a millimeter, has been chosen 
 as this unit. The micron, “, sometimes used, is one-thou- 
 sandth of a millimeter. It will be noticed that on the charts 
 of the spectrophotometer readings of the sixteen colors else- 
 where in this paper that certain wave lengths have been 
 marked Red, Orange, Yellow, Green, and Blue. Abney states 
 that the ranges of the wave length of certain colors are as 
 follows: 
 
 Colors Wave Lengths in Millimicrons 
 Mamamarine Glue .......... from 446 to 464 
 Me, ee ee 464 500 
 Seeireen..s..........--- 500 AD BY ©. 
 a 513 578 
 eae 578 592 
 ee es 592 620 ; 
 eer 620 end or about 720 
 
 Theoretically a pure spectral color has only one wave length, 
 and the above figures represent all the spectral colors which 
 fall under the heading of Blue, Green, Yellow, ete. 
 
 The spectrophotometer may be set on any one of these wave 
 lengths and the percentage brilliance in comparison with the 
 block of Magnesium Carbonate read. <A series of readings at 
 
 * Jour. Optical Soc. Am., 5: 469 (1921). 
 
244 Color Systems, Colorimeters, Etc. 
 
 various wave lengths are taken and a curve plotted as on page 
 248. These curves are commonly called spectral reflection 
 curves. 
 
 Mees* states that ‘‘the quantitative measurement of color 
 is undertaken by means of an instrument termed the spectro- 
 photometer, which is essentially a spectroscope with photo- 
 metric attachments. In this instrument any portion of the 
 spectrum can be isolated and divided into two portions having 
 the same color and adjacent to one another. Into one of the 
 beams is introduced the colored object to be measured, which 
 produced an absorption of the spectral region in question. 
 The other beam is.then darkened by some photometric means 
 until the two patches, as seen through the eyepiece of the 
 instrument, appear of equal intensity. Since the amount of 
 darkening which has been introduced photometrically is known 
 and is equal to the amount which has been caused by the ab- 
 sorption of the colored object, we can read from the instru- 
 ment the quantitative value of the absorption at any point of 
 the spectrum. This is repeated throughout the spectrum, step 
 by step, and a curve of absorption against the wave length of 
 the spectrum is obtained.”’ 
 
 FIGurE 88 
 
 THE KEUFFEL AND ESSER COLOR ANALYZER IN USE AT THE BUREAU OF 
 STANDARDS, 
 
 The Keuffel and Esser Color Analyzer.—Several years ago 
 the Keuffel and Esser Co. developed a spectrophotometer 
 
 <e * Ind. and Eng. Chem., 18:8, 729. The Measurement of Color. C. E. K. 
 Mees. 
 
Color Systems, Colorimeters, Etc. 245 
 Se 
 based on the ideas of Mr. Irwin G. Priest, of the Bureau of 
 Standards, which has simplified the process of obtaining spec- 
 tral reflection curves of an opaque body, such as a paint chip, 
 or spectral transmission curves of transparent liquids and 
 solids, to a great extent. While the Color Analyzer has been 
 greatly improved upon recently over the instrument used in 
 these tests, the underlying principle is the same. A descrip- 
 tion of the instrument used, together with a discussion of some 
 of the later improvements, follows. It is believed by the 
 writer that this Keuffel-Esser Spectrophotometer is the best 
 instrument of its type that has ever been developed. 
 
 The instrument, which is a direct reading spectrophoto- 
 meter, consists essentially of four parts: 1. A spectrometer ; 
 2. A photometer; 3, A light source; and 4. A holder for trans- 
 parent substances. 
 
 1. The Spectrometer—To illustrate the principle of the 
 spectrometer: if a beam of white light, admitted through a 
 narrow slit, falls upon a prism, it is broken up into its com- 
 ponent parts containing all the hues of the visible spectrum, 
 Red, Orange, Yellow, Green, Blue, and Violet, and their vari- 
 ous combinations. Now, if a movable screen, with a narrow 
 shit cut through it, be placed on the other side of the prism 
 and properly adjusted, only one color will pass through the 
 sit. If the position of the slit be moved lower or higher, 
 another color will pass through, ete. 
 
 The principle of the spectrometer is the same. The hght 
 enters through objective lenses and a fixed entrance slit, passes 
 through a dispersing prism and out through a fixed exit or 
 eyeslit. The only difference lies in the fact that the prism is 
 rotated instead of the eyeslit being moved. The dispersing 
 prism is mounted on a platform which is turned by a calibrated 
 drum carrying a wave-length scale. To set the instrument 
 on a particular color, or rather wave length representing that 
 color, it is only necessary to turn the drum to that wave length — 
 and the corresponding color will appear in the spectrometer. 
 
 A bi-prism is placed in the spectrometer in order that the 
 light may be sharply divided into an upper and lower half of 
 the field. The upper half is illuminated by the standard, or 
 block of Magnesium Carbonate, and the lower half by the 
 sample to be tested. 
 
246 Color Systems, Colorimeters, Etc. 
 
 9. The Photometer—The direct reading rotating dise photo- 
 meter consists of two sector dises, each with two opposite 90° 
 openings. The discs revolve around the same center and in the 
 same direction. The angular opening between discs is set by 
 means of turning the knurled head to which the photometer 
 scale is attached. These alterations are made while the dises 
 are in motion at high speed. 
 
 The purpose of the photometer is to alter the brilliance of 
 the block of Magnesium Carbonate so that a match may be 
 obtained with the sample at the different wave lengths. The 
 scale of the photometer reads from 0 to 110, and in the speci- 
 fication of a color the settings of this scale are plotted against 
 the particular wave lengths. The fact that the scale reads to 
 110 per cent permits the approach to the matching point of 
 samples of high reflection or transmission values from both 
 sides, resulting in greater accuracy. 
 
 3. The Light Source-——The light source consists of a 
 spherical housing, in which are placed two 400-watt stereopti- 
 con lamps. The interior of this housing is coated with a 
 special white paint to give bright and diffuse reflection. Due 
 to the high heat developed by the lamps, the housing is equip- 
 ped with radiation ribs and the whole unit is ventilated and 
 kept cool by a motor-driven suction fan. 
 
 Operation of the Spectrophotometer—The sample and the 
 standard block of magnesium carbonate are placed in the back 
 of the housing. The light reflected from them passes out 
 through the front of the housing toward the photometer which 
 it enters. 
 
 The spectrophotometer is operated by setting the wave- 
 length drum on the spectromoter at, for example, 600 mu. The 
 brilliance is then obtained by rotating the photometer scale 
 until an intensity match has been obtained. Ordinarily paint 
 chips do not show any particularly sharp fluctuations in the 
 spectral reflection curve, so that a reading taken at every 20 
 mu throughout the scale is sufficient. If, after the curve has 
 been plotted, any sharp dips are found, the readings may be 
 taken at every 10 mu for this portion of the curve. 
 
 Some trouble in the past has been experienced with. the 
 slight variation of different blocks of Magnesium Carbonate, 
 some being whiter or less white than others. This has caused 
 slight variations in the readings obtained on two different 
 
Color Systems, Colorimeters, Etc. 247 
 La 
 instruments. With this instrument each Magnesium Carbon- 
 ate block is thoroughly standardized and certified by the 
 manufacturers before delivery. 
 
 The adjustment on the photometer to increase the illumina- 
 tion of dark samples is so arranged that when the lever is 
 moved the readings must be divided by four instead of by two. 
 This adjustment increases the illumination of very dark sam- 
 ples to a great extent and enables the operator to obtain a 
 match easily in both halves of the field. 
 
 FIGURE 89 
 
 Conversion of the Spectrophotometer Readings to the Trich- 
 romatic System.—Ives* gives directions for computing the 
 Red, Green, and Blue sensations of a sample whose spectral 
 reflection curve is known: 
 
 *Journal Franklin Institute, January, 1923, page 43. 
 
248 Color Systems, Colorimeters, Etc. 
 
 ‘Multiply the reflection factor (given by the spectrophoto- 
 
 meter) at each wave length by the Red, Green, and Blue sen- 
 sation values and also by the white light spectral luminosity 
 
 BRILLIANCE 
 
 KEUFFEL AND ESSER COLOR ANALYZER 
 BLUE GREEN YELLOW ORANGE RED 
 
 WAVE-LENGTHS IN MILLIMICRONS 
 Our results at the Bureau of Standards 
 ----~-Keuffel & Esser results their laboratory 
 
 FIGURE 90 
 
 TABULATION OF READINGS FOR ABOVE CHART 
 
 Wave Our K. & E. Wave Our K. & E. 
 length results results length results results 
 +40 30.0 24.5 580 41.1 39.7 
 460 S23 32.4 600 36.0 35.3 
 480 39.8 37.4 620 34.6 31.8 
 500 43.9 42.4 640 30.1 29.7 
 520 49.7 47.8 660 29.3 29.2 
 540 47.8 47.0 680 29.4 27.4 
 
Color Systems, Colorimeters, Etc. 249 
 EASTMAN UNIVERSAL 
 COLORIMETER HESS-IVES 
 FIGURE TINT PHOTOMETER 
 
 -GREEN -BLUE -RED NEUTRAL RED GREEN BLUE 
 1OO Tere 
 90 90 
 80 80 
 70 70 
 60 60 
 50 EO 
 4O es 
 Re 50 
 20 Be 
 10 1O 
 O O 
 
 —— Our results 
 
 ----Eastman Kodak Co. results their laboratory 
 
 TABULATION OF READINGS 
 Our KE. K. Co. 
 resuits results 
 REO ig fein gos ss ce es 0 0 
 ol Se 4.4 Dak 
 Oe 17.8 15.4 
 MUMMIES. 30.9 30.9 
 
 me. 
 
 — Our results 
 
 TABULATION OF 
 
 READINGS 
 ROU RA re er ee 30.5 
 GLYCO cats edt 48.5 
 BiG yah eee 38.0 
 TLD ORLive eter 44.0 
 
 CALCULATIONS FOR POLAR CO-ORDINATE CHART 
 
 Our “i. K> Co: 
 results results 
 
 216° 
 
 eee eee ote oer eee ee 
 
 eee eee ee eee 
 
 2 LUE 
 10.25 
 
 FIGURE 91 
 
 value“ (given on page 25 of the same paper). The areas 
 of the resultant curves, expressed as fractions of the areas 
 
 *At the present time there is considerable controversy between color ex- 
 perts with regard to what sensation and luminosity values should be accepted 
 as Standard for the purpose of calculation. The method as given above is 
 
 essentially correct. 
 
 the near future. 
 
 The standardization of these figures is anticipated in 
 
250 Color Systems, Colorimeters, Etc. 
 
 of the original curves, are the required sensation and lumi- 
 nosity values.’’ 
 
 In the same paper is given a method of obtaining the hue, 
 saturation, and brilliance of a sample whose spectral reflee- 
 tion curve is known. 
 
 Keuffel and Esser have devised a slide rule, by means of 
 which these values may be calculated without involving higher 
 mathematics, such as computing the area under the curves, 
 ete. 
 
 One of the objections to spectrophotometers in the past has 
 been the necessity of using so many figures, or a curve plotting 
 these figures, in specifying a color. By use of the calculations 
 eiven above, or by means of the slide rule mentioned, a color 
 may be specified by giving three values, the Red, Green, and 
 Blue sensations. 
 
 Hardy Recording Spectrophotometer.—Arthur C. Hardy, 
 Assistant Professor of Physics, of the Massachusetts Institute 
 of Technology, has recently developed a new type spectro- 
 photometer. It has, however, not as yet been placed upon 
 the market, and a complete description is not available. The 
 
 following brief description of the instrument has been fur- 
 
 nished the writer: 
 
 The instrument is a recording spectrophotometer. The 
 present model is designed especially for measuring the color 
 of reflecting samples, and operates on the following principle: 
 Light is alternately reflected from the sample and from mag- 
 nesium carbonate. Both beams are caused to travel the same 
 path and to disperse into spectral components by means of 
 a prism. If at a given wave-length the reflecting power of 
 the sample is different from the magnesium carbonate, an 
 alternating light intensity is produced. This sets up an al- 
 ternating current in a photo-electric cell, which eurrent is 
 amplified and is used to balance automatically the two light 
 intensities. At the same time a separate motor changes the 
 wave-length under observation. A pencil moving on a drum 
 draws the spectrophotometrie curve with good rapidity and 
 with a precision exceeding that of visual instruments. 
 
 Conclusions and Discussion.—Color charts are believed to be 
 of limited value, for several reasons. A color-chart system, 
 for instance, may contain several hundred shades or tints of 
 one color, such as blue, but might not contain a blue which 
 
 i a ee me 
 
 7 
 
Color Systems, Colorimeters, Etc. 251 
 ee ___.............___ 
 would match a color chip selected by an individual. Color 
 charts are usually prepared with flat or matte surface chips 
 which are difficult to match with a gloss chip. Color-blind 
 operators cannot use a color chart with any degree of ac- 
 euracy. The influence of one chip upon another, because of 
 the effect of color environment, makes comparison difficult 
 when a chip is to be matched with a chart. On the other hand, 
 color standards preserved in the form of color chips have 
 always proved useful to the paint manufacturer. This is on 
 account of the fact that the eye is possibly more accurate for 
 matching colors than any instrument as at present developed. 
 Thus, for instance, if a definite color (freshly prepared) is 
 submitted to a manufacturer on a color chip, the manufacturer 
 will be able to match it with greater accuracy than from a 
 specification written from colorimetric readings. 
 
 Because of the present lack of refinements in colorimeters, 
 that would guard against experimental errors of a substantial 
 nature, it is the writer’s belief that such instruments will not 
 be of enormous value to manufacturers for ordinary work. 
 Colorimeters could, however, be of service in the following 
 manner. Suppose, for instance, that a paint manufacturer 
 produces a colored paint or enamel, and that he paints it out 
 and attaches it to his color card as one of his standard shades 
 or tints always available to the trade. If he makes a reading 
 on this color chip with a colorimeter, such, for instance, as 
 the Eastman or Bawtree, he can record his readings for future 
 use. If several months later he thinks some change in his raw 
 materials has occasioned differences that give him difficulty 
 in matching every batch of the same tint, he can then have 
 recourse to his colorimetric standards. By setting the instru- 
 ment to his recorded values for the color desired, he will ob- 
 serve his original standard color which will guide him in 
 matching up his paint. If substantial changes have taken 
 place, he can make such adjustments in the formula as are 
 necessary to lead him to the original desired tint. It was 
 found however that black and many dark shades are of such 
 low reflective value as to come outside the range of a colori- 
 meter. Their use therefore is limited. 
 
 Colorimeters might be of further use in the following man- 
 ner: For instance, a color is desired in some far-off place, and 
 
252 Color Systems, Colorimeters, Etc. 
 
 the reading on the color may be 20 Red, 40 Green, 30 Blue. 
 Several days’ time might be required to paint out a sample of 
 the material, dry it, and then submit it by mail. Telegraphic 
 communication, however, could be made, stating that paint of 
 the above specification was desired. Within a few minutes’ 
 time the reader in another section of the country could set his 
 colorimeter to the specification, observe the color desired, and 
 match it fairly well. Thus specifications could be transmitted 
 by telegraph and be thoroughly understandable. For military 
 purposes such a method would be useful. 
 
 Asa result of growing interest in the subject of color defini- 
 tion, instrument manufacturers are making rapid progress in 
 the development of colorimeters. Instruments of even greater 
 accuracy than those now available may possibly appear in the 
 near future. It is believed that such instruments would be of 
 value in any paint laboratory. 
 
 With the tint photometer used in our work, observable 
 differences were recorded between colors that although very 
 similar could also be differentiated by the naked eye. Read- 
 ings, however, were made only upon one instrument and by 
 one observer, and comparisons cannot be drawn as to the rela- 
 tive accuracy of two different instruments of the same make 
 when read by various observers. For matching old colors, 
 this instrument could not be set up with recorded values given 
 in red, blue and green, as has been referred to above, with the 
 ordinary type of colorimeter. It will be seen, therefore, that 
 its use in this direction would be somewhat difficult to apply, 
 whereas, of course, three readings could be set individually. 
 For this reason the ordinary colorimeter referred to above 
 might prove superior to the tint photometer, although this 
 latter type of instrument is relatively imexpensive, easy to 
 handle, easier upon the eyes, and possibly more accurate. 
 
 If a manufacturer should make a reading on a color chip 
 with the spectrophotometer and then desire at a later date to 
 see whether any changes had occurred in the chip or in the 
 paint made with the formula, this instrument could not, of 
 course, be used for reproducing the color. His method would 
 be to submit his paint to a reading on this instrument and 
 
Color Systems; Colorimeters, Etc. 253 
 
 ascertain whether any change had taken place. Two colors 
 giving the same reading on the spectrophotometer are always 
 exactly alike to the eye under all conditions of illumination. 
 It is possible, however, that two colors giving different read- 
 ings on the spectrophotometer might also give the same ap- 
 pearance to the naked eye, such, for instance, as camouflage 
 colors. A rather long time is required to make readings on a 
 spectrophotometer and the instrument is relatively expensive. 
 Normal color vision is not needed to operate it. A specifica- 
 tion for a color according to a spectral reflection curve could 
 not easily be transmitted by telegraph. If received by mail, 
 one familiar with color work could immediately get some idea 
 as to what the color referred to looked like, but it would be 
 necessary for him to experiment with several different tints 
 and shades of the color before he could match it exactly on 
 the spectrophotometer. It is without doubt the most accurate 
 instrument for defining a color. In large laboratories it is 
 believed that the spectrophotometer would be of considerable 
 use and perhaps of value. 
 
 i 
 
 In the control of color in the paint industry, long experience 
 has demonstrated that in a mixture of pigments a fixed for- 
 mula cannot be relied upon to produce a series of ‘‘batches”’ 
 all uniform in color, no matter how accurately the propor- 
 tional quantities may be weighed, or measured. It has also 
 been established that, in a series of ‘‘batches,’’ if each batch 
 be matched up to the batch immediately preceeding, there 
 will ensue a ‘‘drift’’ away from the original color that soon 
 becomes pronounced; and this occurs whoever does the 
 matching. 
 
 To minimize difficulties of this kind, it has been customary 
 to match the different batches in process of production up to 
 daily ‘working standards,’’ which, in turn have each been 
 checked against a carefully preserved master standard, which 
 is presumed to have remained practically unchanged. This 
 master standard is usually a sufficiently large portion from 
 some original batch whose color has been adjusted to a shade 
 arbitrarily chosen as the desired standard, this portion being 
 then filled into a number of small packages, hermetically 
 sealed, and set aside for future use as required. 
 
254 Color Systems, C olorimeters, Etc. 
 
 Such standards cannot, unfortunately, be relied upon to 
 maintain their integrity for an indefinite period of time; conse- 
 quently, it is highly desirable to have available some scientific 
 method of measurement or specification that would positively 
 identify the color of any selected standard, enabling a record 
 of it to be kept in quantitative terms of fundamental physical 
 units. 
 
 Color is a psychological sensation and as such is not readily 
 measurable, yet the stimulus or immediate cause of the sensa- 
 tion is easily measurable, and expressible in terms of funda- 
 mental physical units. The additional fact that a definite 
 stimulus excites the same specific response in all individuals 
 possessing normal chromatic vision enables the spectral re- 
 flection curve to be employed as a sound indirect measure of 
 color. 
 
 In setting up color standards for the purpose of uniformity 
 of color in any commercial commodity, the real objective de- 
 sired is a fixed and definite stimulus value, this being, in fact, 
 the only part of the complete process of color vision over 
 which the manufacturer of the commodity can hope to exercise 
 control. 
 
 To sum up the principal points in connection with spectro- 
 photometry as a method of color analysis, the recent work of 
 Sub-Committee XVIII, D-1, of the American Society for Test- 
 ing Materials might be referred to, the line of reasoning being 
 developed as follows: 
 
 First, when a painted surface, or other object, is suitably 
 illuminated in such a manner that the character of illumina- 
 tion can be specified, the incident radiant energy is reflected in 
 a selective way. Second, the inherent properties of any 
 sample of radiant energy which determine its capacity as a 
 color stimulus are completely specified by its spectral distribu- 
 tion. Third, the spectral distribution is fully exhibited in the 
 spectral reflection curve; consequently, so far as the manufac- 
 turer is concerned, the curve serves as a measure of the color 
 of the product, and specifies the sensation that will certainly 
 be produced in the eye of every observer who possesses nor- 
 mal chromatic vision. 
 
 The great value of the curve to the manufacturer of paints, 
 or other objects involving similar color problems, lies in the 
 fact that it may be preserved indefinitely as a permanent 
 
 me 
 
Color Systems, Colorimeters, Etc. 255 
 as 
 record of the stimulus value of any original standard, and if 
 any such standard should change in color, either from long 
 storage, exposure to light, or other cause, such change can be 
 detected, its extent measured, and the true color restored or 
 a correct new sample prepared, without SUS comparison 
 with any other sample whatever. 
 
 PartiaL List oF Books on Couor FoR REFERENCE WorK 
 
 Color and Its Applications. M. Luckiesh. 
 
 Color and Methods of Color Reproduction. Martin and 
 Gamble. 
 
 Color. G. W. Thompson. Proceedings A. 8. T. M., 1923. 
 
 Color Standards and Nomenclature. Ridgway. 
 
 Farbenfibel. W. Ostwald. 
 
 Die Grundlage der Messenden Farbenlehre. W. Ostwald. 
 
 Die Farbenlehre I, I]. W. Ostwald. : 
 
 Die Farbe. W. Ostwald. 
 
 The Theory and Practice of Color. Snow and Froelich. 
 
 Farben, Farbensehen. Carl Hensel. 
 
 Traite de la Couleur. A. Rosenstiehl. 
 
 A Handbook on the Theory of Color. G. H. Hurst. 
 
 The Colorist. J. A. H. Hatt. 
 
 Systems of Color Measurement. H.S. Busby. A.S. T. M. 
 Proc., 1922. 3 
 
 Problems of Color Measurement. H.S. Busby. A.S. T. M. 
 Proc., 1921. 
 
 SECONDARY REFERENCE SAMPLES FOR TINTS 
 AND SHADES 
 
 Reference is made at the beginning of this chapter on color, 
 to the old type reference standard in use in paint factories. 
 A request from one manufacturer for information as to the 
 best method of keeping such standard samples for shades 
 and tints of house paints, was submitted a few years ago by 
 the Secretary of the Association to a number of technical ex- 
 perts in the industry. The answers received showed a wide 
 diversity of opinion on the Spares They are summarized 
 below. 
 
 (a) For the past twenty-five years all standard samples were tinted 
 on a base of “Green Seal” zine ground in light colored paraffine oil in semi- 
 paste form in the regular manner. 
 
 We find that delicate colors, such as light blues and greens, in fact, any 
 color, does not change its shade. The only thing is that a tinter that matches 
 
256 Color Systems, Colorimeters, Etc. 
 
 the shades must allow for sample color being cleaner and clearer in tone 
 than the color he gets by tinting the regular paint. 
 
 (b) We know of no vehicle which may be used with pigments which 
 will not change color on storage, whether exposed to light and air or kept 
 sealed. The most satisfactory way to set a standard shade is to use raw 
 materials of given specifications and make sample freshly each time color is 
 to be determined. We have not carried on any extensive experiments along 
 the lines suggested, but do not believe that it is feasible to use neutral 
 mineral oils, as these will not allow for the difference in color between the 
 dry and wet paint where drying oils are used. 
 
 (c) Standard samples ground in corn oil to a paste consistency, using 
 zine as the base for tints made from white bases, will give very satisfactory 
 results. I have also used neutral oil to some extent, but believe the corn oil 
 better for general work. 
 
 (d) When making up house paints, we match them with the dry sample 
 on the color card and also with a sample taken from the last batch made 
 and in this way we keep the shade uniform. 
 
 (e) We do not hesitate to say that no thoroughly satisfactory method 
 has yet been devised. 
 
 Any proposed method must depend upon factory procedure, that is, 
 whether the shading is done in the liquid mixer or while the batch is m 
 paste. Both ways have their advantages and disadvantages and depend on 
 the plant. 
 
 With proper care and attention coupled with a reasonable experience, 
 we do not have any appreciable complaint which might justly be laid at 
 the door of any improper standard, but in this connection we might ask the 
 pertinent question, “Why should a properly kept standard change if the 
 goods themselves hold their integrity after being filled and stocked?’ If the 
 goods do not hold, without radical or pronounced change, for the indefinite 
 time they may remain in stock, then high accuracy in a standard type sample 
 becomes obviously an unnecessary refinement because neither the rate of 
 change nor its final extent can be predicted, no matter what the starting 
 point. 
 
 There are limits, of course, but scientific accuracy in such cases is not 
 to be attained by the use of a perfect type sample. 
 
 What, for instance, is the use of a perfect type sample of a pale tint of 
 Chinese Blue in lead or zine? After the goods have been in the ean a few 
 weeks, or less, the shades will never again match exactly the “perfect 
 sample,” although upon being painted it will “come back” more or less by 
 the time the paint is dry. F 
 
 These little problems are a part of the paint maker’s art and must usually 
 be solved by each one for himself, according to his ability and environment. 
 
 Glycerol, paraffin oil, refined linseed, poppy oil and» various other vehicles 
 have been tried with varying degrees of success, but we find that after all 
 it is perfectly practicable in the vast majority of cases to secure reasonable 
 uniformity by working from a type sample taken from a regular commercial 
 batch. The complaints arising from variations in shade, due to imperfect 
 type samples, are wholly negligible when compared with the howls that 
 come in because the paints in the cans do not match the color cards, and in 
 both cases the complaints come almost invariably from the inexperienced 
 consumer. 
 
 (f) colors ground in water-white mineral oil will hold their color 
 permanently on storage. Such colors ground up in order to maintain stand- 
 ard colors should be kept in opaque or very dark colored, tightly sealed glass 
 Jars, properly labeled for identification. 
 
 (g) We use straight refined linseed oil in grinding out our standard 
 shades for house paint colors. These we use for one year to shade to; then 
 we regrind for new standards to be used in the future. 
 
 (h) We have always ground our standard samples in winter strained 
 lard oil and have found that this held the color very well. 
 
 (i) Our experience is that if these samples to be retained as standards 
 for matching work, are ground in pure winter strained and refined lard oil, 
 there will be as little action as can be had with any oil with the added ad- 
 
Color Systems, Colorimeters, Etc. 257 
 
 vantage that they will not be as likely to skin over. In removing this skin 
 some of the tinting color is lost; however, on delicate blues and greens, 
 there is always likely to be some fading. 
 
 (j) We have experimented with various methods of maintaining stand- 
 ard samples for shade on house paints, and find that a good grade of zinc 
 oxide ground in corn oil, tinted to the standard color with pure coloring 
 matter, will retain shade better than anything else we know of. 
 
 This information was received. previous to the study of 
 colorimeters and spectrophotometers which is given above. 
 These instruments have just come into the industry and as 
 yet but few laboratories possess them. Until laboratories are 
 equipped with such instruments and with personnel to prop- 
 erly operate them, they must rely on the older methods of 
 keeping standards. In this connection, it is probably wise to 
 again point out the fact that the eye will more readily detect 
 very slight differences in a tint than will a colorimeter. For 
 this reason, if secondary standards could be developed, they 
 would serve a very useful purpose in the industry. 
 
 A method which the writer has been experimenting with 
 during the past summer, consists in applying to very thin, 
 clear glass plates four inches square a quantity of the color 
 of which a secondary standard is desired. The plate is spun 
 to produce a thin, uniform film. The coating is allowed to dry. 
 Previous to the spinning operation, it is absolutely essential 
 that the paint be thoroughly screened to remove all specks. 
 After drying for a period of one day with interior flat wall 
 paints or four days for exterior oil paints, one-half of the 
 surface of each panel is flow-coated with a thin nitrocellulose 
 lacquer made by mixing together 100 parts by weight a 32 oz. 
 solution of 14 second viscosity nitrocellulose in butyl acetate 
 and 150 parts by weight of toluol. Five parts by weight of 
 tricresyl phosphate is added as a plasticizer. This lacquer 
 will usually dry in 15 to 20 minutes under normal conditions, 
 and but little difficulty has been had with the lifting of the oil 
 films over which it is applied. It is, of course, necessary that 
 these films should be quite dry and firm before the lacquer is 
 applied. 
 
 These panels are kept as reference standards, and when a 
 batch of paint is to be tested for color, a portion is placed 
 upon an uncoated plate of the same type of glass, flowed out, 
 and a comparison immediately made. The operator views the 
 color in comparison with the secondary standard, looking at: 
 the top surfaces and then reversing the plates and looking at. 
 the under surfaces. The purpose of the lacquer is to serve as: 
 a continuous film to prevent oxidation of the color due to long 
 
258 Color Systems, Colorimeters, Etc. 
 
 standing. It also serves to present a type of surface which 
 appears wet and therefore is useful in comparing the color 
 of wet samples. 
 
 Tests made by this method, in which the coated specimens 
 were kept for a period of three months in a dark moisture 
 saturated chamber to cause darkening, indicated that but little - 
 darkening or change in color had taken place. 
 
 The method, however, is not perfect by any means, and is 
 simply offered as a suggestion for further research on the 
 part of laboratories having this matter under consideration. 
 It is not recommended for adoption. 
 
CHAPTER XVI 
 OIL ABSORPTION TESTS 
 
 Probably the most widely used oil absorption test is that in 
 which the pigment is rubbed up with a spatula with sufficient 
 oil to just form a paste. This quick and convenient method 
 usually gives results which are comparable with the oil re- 
 quired to grind pigments in a mill to paste form. It is out- 
 lined below as a standard test and is to be preferred for most 
 factory control work. There is also given below an outline 
 
 Brown Burette for Oil With 1 cc. Pipette Graduated to 1 /10 ce. Main 
 Bulb Holds 100 ce. 
 
 FIGURE 92 
 
 of the Gardner-Coleman method for determining oil absorp- 
 tion, which, while giving valuable information regarding cer- 
 tain characteristics of a pigment, is not used widely in paint 
 factories. Its chief application is in pigment factories where 
 close control of each batch of product is a matter of great 
 importance. 
 
 The rather extended discussion of this method which ap- 
 pears in this chapter may be excused because of the desira- 
 bility of presenting an explanation of the phenomena involved 
 when pigments absorb oil. 
 
260 Oil Absorption Tests 
 RR RNE SEIT 
 
 Standard Rub-Out Test For Oil Absorption.—Take exactly 
 one (1) gram, or any multiple thereof, of the pigment. Place 
 upon a marble slab or glass plate, carefully weigh a dropping 
 bottle containing some refined linseed oil, the bottle to be 
 fitted with a ground in pipette and rubber bulb. Note the 
 weight of the bottle and oil. Gradually add, drop by drop, 
 the refined linseed oil to the pigment, and after the addition 
 of each drop, by the use of a stiff spatula, thoroughly incorpo- 
 rate the oil with the pigment. The test is complete when ex- 
 actly enough oil has been incorporated with the pigment to 
 produce a very stiff, putty-like paste, which does not ‘“break’’ 
 or separate. Weigh the bottle and oil. The difference in 
 weights equals the weight of oil used. Calculate to pounds 
 of oil required to exactly ‘‘wet’’ one hundred (100) pounds 
 of pigment. : 
 
 In the writer’s laboratory the type of burette depicted above 
 is used for conducting this test. The number of cubic centi- 
 meters of linseed oil used is multiplied by the specifie gravity 
 of the oil in order to obtain the weight of oil required to satu- 
 rate the pigment. This test has been run upon a number of 
 pigments found in the laboratory, with the results given below. 
 Some of the pigments reported on had been in the laboratory 
 for several years. Slightly different results might be obtained 
 with more recent samples. 
 
 Or ABSORPTION ON SomE PIGMENTS BY SPATULA-RUBBING 
 
 MrrHop 
 
 Figures show pounds of raw oil required to form a paste with 100 pounds 
 of dry pigment. 
 WHITE PIGMENTS 
 
 Zine Oxide (Western Leaded). 13 China. Glay =o... tgs 29 
 Zinc Oxide (Western Leaded). 12 Tale ....<. iets eee 37 
 Zinc Oxide (American Process) 21.5 Asbestine (pulp)-< 234-5. scne 29 
 Zine Oxide (French Process) .. 19.5 White Mineral Primer..\.....5 13 
 Zine Oxide (French Process).. 16 White Mineral Primer......... 14 
 Lithopone (low oil absorption) 14 Whiting: ¢Gilders) (255 eee oe 
 Lithopone (light-proof) ....... 18.5 Whiting .(Gilders) sa. ..ee ae 17.5 
 Zine, Carbonate acnssea eee 38 Whiting -(Wloated) tae nee 15 
 Zine “Sulphide 0.46 kijeewe eee 26 Whiting. 12.20%. eee 17.5 
 Titanium Oxide 2 <3. sess 45.5 Barytes «..¢.5 sas eee (es 
 Titanium Oxide (pure)....... D1 Barytes «s.2, » +s ssl en ee 9.5 
 Titanox (Calcium sulphate Blane Fixe .os.:45) <a 5 eee eee 15 
 DSO): Gn} sale Oo cke eee cares 29 Barium Carbonate \3e2 eae 16 
 Titanox (Calcium sulphate Gypsum (Hydrated) ......... 29 
 DEBE)“. vend See 23 GYPSUM +... eve ele eee 20.5 
 Titanox (Barium sulphate Bentonite Clay.) 225 seeeeeee 24 
 DASCY Va cutee ee se ee eee Zi. Silica (Floated) (32233. a0a eee 29 
 White Lead (corroded)....... 10 Silica (Crystaline) 23.5 e508. 16.5 
 White Lead (basic sulfate)... 138 Diatomaceous Earth ......... 29 
 Antimony Oxide. 2 7601 14 = OO la 152 
 
 Ching Clay .-.0.6 2 see eee 30 
 
Oil Absorption Tests 261 
 
 RED AND YELLOWS 
 
 American Vermilion .......... 9.5 
 Deep English Vermilion....... 10 
 Eee yc. vise ce eee 11 
 ie 10 
 Deedee MINCrAl . 06s. .s ee ee es 11 
 Tuscan Red (24% Fe203)..... 16 
 Tusean Red (28.5% Fe203).... 23 
 Orange Chrome Yellow........ 9.5 
 Orange Chrome Yellow........ 12.5 
 Orange Chrome Yellow (deep). 11 
 MUMBEREES Std Ss Go ee ee eo ss 31.5 
 Deep Para Red (10% Para on 
 Whiting-Barytes Base)...... 16 
 
 Maroon (10% Alphanaphthyl- 
 amine in Whiting-Barytes 
 I erty. oN ais 6s oes o's 20.5 
 
 Ortho Toner (90% Orthoan- 
 isidine on Lake Base)...... 54 
 
 Ortho Red (10% Orthoanisi- 
 dine on Whiting Base)...... 23.5 
 
 Searlet Lake (35% Xylidine 
 Searlet on Blanc Fixe Base) 29 
 
 Methyl Red (2% Lithol on 
 orange mineral base)....... 12 
 
 Orange Lake (16% _ scarlet 
 Manderine on Whiting-Blanc 
 ROTO ore he oe eee 21.5 
 
 TROSG oe LO ae eta e nee ace ae ee Shae 29 
 Toluidine Red (50% on Blanc 
 BLS OW ISHBO badectoniclarw sity: ohohen ails 30.9 
 Venetia no Gel avs c.c eh mie es ola tine 21.5 
 AVL S Tie PUCUGi a bs rene ce oni fe ate 13 
 Indian Red (96% Fe203)..... 18.5 
 
 Prince Mineral (34% Fee203).. 23 
 Metallic Brown (61% Fee03).. 16.5 
 BURDISHLOSIGG cise cent se o's 15 
 Purple Oxide (82% Fe203)... 10 
 Canadian Oxide (91.5% Fe203) 25 
 Italian Raw Sienna 
 
 ; (G4 orb eos Siete cas ce nates 52 
 Raw Sienna (American)...... 40 
 Burnt italian Sienna >... ...... 28 
 RUTH Ue LOT Dg ie a teases etal oa 28 
 FLL OCT aie cay So erete dee, ateela oo 26 
 Raw Turkey Umber 
 
 FAG Tom Bea Os \eicre es Ghee ares 44 
 Burns (MDS es ees ate gtostacs 39 
 Golden Ochre ..... 1 oR RRR 16.5 
 Yellow Ochre “F. A. R.”....... BH 
 Ochre (American): ........... 18.5 
 Ferrite Yellow (Dark Orange). 32.5 
 PO elie Pitile coe etttens debates a okes 29 
 
 GREENS AND BLUES 
 
 fMrramerine Blue ............ 35.5 
 
 Medium Grinding Green (30% 
 green on clay Barytes base) 12 
 
 Extra light chrome green (14% 
 
 on Barytes-clay base)...... TS 
 
 Medium Chrome Green (16% 
 
 Strong Grinding Green (16% 
 
 on Barytes-clay base)....... 17.5 
 Blue Shade Green (16% on- 
 
 Blane Fixe-clay base)....... 11 
 Chromium Oxide “Pod... 3: si... 32 p bres" 
 
 Blue Lead (Basic Sulphate)... 7.5 
 
 on Farytes-clay base)...... 16 Blue Lead (Basic sulphate)... 12 
 Dark Chrome Green (16% on 
 
 Barytes-clay base).......... 16 
 
 BLACKS 
 
 SS 27 Lampblaek seit oeate se ais 107 
 EE ory aig a we cos ye 4T.5 Beaampp la Chtt,sc tes eras le oa 111 
 Se 39 Thermatomic: Black 2) .vao..: 31 
 UMMM ACI ey oo ww 93 Keystone: Fillers. 2. ee tas 19.5 
 Des OL ALOE a 99 Black Iron Oxide _ (Precipi- 
 ROR Gh ee ee 114 tH CCUY Bes tha capes ore aes 33.0 
 
 It should be pointed out, however, that there is no sharp 
 line of demarcation for any given pigment between a paste 
 obviously too thin and one just as obviously too stiff. It 
 should also be pointed out that the wetting power of the lin- 
 seed oil used is profoundly changed by oxidation, acid value, 
 and all types of refining and cooking. The greater the oxida- 
 tion, the greater the wetting power as arule. It might further 
 be mentioned that it is sometimes difficult, when using the 
 
262 Oil Absorption Tests 
 
 same grade of linseed oil, to obtain pastes having the same 
 vield value or mobility with pigments of the same type from 
 two different sources. 
 
 One might reasonably suspect that if the absorption were 
 expressed in terms of volume instead of weight there would 
 be a closer concordance, and that perhaps it might show a 
 definite relationship to specific surface. Microscopie examina- 
 tion, for instance, of zine oxide shows it to be as fine or finer 
 than toluidine red. While the zine requires approximately 
 1.22 volumes of oil to make a good paste, toluidine red, with 
 a presumably smaller specific surface, requires about 2.10 
 volumes. Instances of this sort may be multiplied, and such 
 discrepancies force us to the conclusion that the interfacial 
 tension between pigments and oil is not only different for the 
 different pigments, but with linseed oil the factors which 
 govern oil absorption, may become an extremely complicated 
 matter. 
 
 OIL ABSORPTION OF PIGMENTS* 
 
 In the following table, the figures give the percentage of 
 pigment in commercial pastes made by grinding the pigments 
 with reasonably fresh raw linseed oil practically free from 
 foots and having an acid number between 2 and 4. 
 
 WHITES 
 
 Aluminum Hydroxide (Commercial Hydrate).............. 40-43% Pigment 
 Asbestine 2.455 ¢5008 s 00's wie shames sweaty Cee nn 68 
 Barytes 2. oie avaaes wen seen Oe ev ewe ae sete 94 
 Blance Fixe .....5 600.006 ¥ ss buw oul cule be Sele 88-90 
 China Clay ‘(Dry)....... ...scucsssbeee eee eee 70 
 Lithopone © 2. oi... ences caus ae ne Uy eee Oot 82-86 
 Silica «(Quartz)) oo ..a ii a oe de eee es ee 73 
 Titaninm Dioxide’ .....42.002 22... 4 eee hale oe 35-40 
 Titanox (25%. TiOe) 2. 05. cota ws eee 80-82 
 Whiting 2... i ees cuba ded bone 63) 
 Basic Carbonate White Lead (Dutch Ee ee he et eo 91-92 
 Basic Sulphate White Lead: ....... is..:...000eeee 88-90 
 Flake White Lead..........0-be0es0ss pies tl 88-89 
 French Process Zine Oxide..::..42.........50 80-83 
 American Process Zine. Oxide (Lead-Free) . ....: 4.20.0 seeen 80-83 
 
 = se: (Leaded)  ....4: Seeneaeeeeee 83-86 
 
 BLACKS 
 
 Carbon Black (Gas) ...cc.ssvc0-4.4 enue. — 
 Drop Black 3) I as er oe ete 
 Ivory Black (Genuine) ......:..1,..0,1.)..., 0 3 
 Lampblack os. 4i6 cs. V0. ed boa oe an ee a 28-34 (Note 4) 
 Iron Oxide Black (Artificial) ...:..........2..) 00 82 
 
 *Table furnished by.F. P. Ingalls, 
 
Oil Absorption Tests 263 
 
 REDS 
 EEE i S00 SP 86-87 
 af “i NO pce a caatats Liss lui's c's; enue sai sng a bc 0Nb 86-87 (Note 5) 
 sg a lacs ain ala eos es e's vane os 6 ets es 43 
 a 40 
 tn ess cio 5m 2 8 oy te et ee eee ees Rerokind i tre rene oi 40 
 aca saison + < sc 6) 90 00 0-40 whe ta te vs 60 ee 70 
 meeeneyvermiion, Pale and Deep............ceewecccccecs 84 
 
 Note 3—A paste containing as high as 20% of a “long” black could be pro- 
 duced, but it would be very stiff. A “short” black is quite firm at 12%. 
 Carbon black is difficult to disperse in raw oil. Special vehicles are usually 
 employed. 
 
 Note 4—Some lampblacks grind shorter than others. Perhaps 380% is 
 a good average figure. Even in this concentration, if too stiff, they might 
 “streak” when used for tinting whites. R 
 
 Note 5—This color is the crystalline basic chromate of lead. 
 
 SE a cgtina ashe 35 (Note 6) 
 SIGS 88 ( Note7) 
 a gC cia la ty a,c ace 00s. @ae 60h 'e sista ey 0oe biapee ace 82 
 Lithol a OS aera AT 
 - SERIE Pe ee ree ee, Si er arr 42 
 UIE A TIZATING) . 0... ws ee he cee ee ees sensens ‘40 
 TE AC ec cn pe oe esc wns vices sp sineenveceus 39 
 sr eee na ox 5 sien Ge bas oe bie Kaleo hbo ole be 42 
 Maroon Toner (Alpha-naphthylamine).................... 30 
 Paranitranilin SMI ANG ES cre oe I el Ow ale ci ome C ae 6 ow, baa a 43-47 (Note 6) 
 EA LNCS iirer Pro fe aa) 6 ask ais od a(tre es Fk ke v0 30-40 
 eng See cv veep en cd ced pe verssvceass 93 
 pee BAKE... 66.3 ok ee eon nse hs tis coat ate & Aaale ele 71 
 re oe sis pu bis Sele ale as oa be mews ba Cae a's 74 
 SG O08 0S a 42-46 (Note 6) 
 I RR ele ac eng ce cts ced ceed ebeyecceuas 80-82 (variable) 
 Venetian Red (Government Standard)..........-esecceee. rue 
 Set Fie tett COKIGC J ae eee te bg te cease 78 
 “s ee TIE CEU G 0) 9 io ann ie bees c chele viesd duerele Se we ote 78 
 YELLOWS 
 Cadmium NITE es ANTI oe oar. hoes aie cheteaie oak Gdn ease aleve wes 79 
 “ PRED TA Ae koko eS, fears ateie Ate te Ses Seo celten viet 78 
 : a Lg Fer a tek A IRR ace RIN) eer tN rts oa 86 
 i etree aie (GENUINE) . 00.6 cee ce coe a dae ole 5D 
 “ i Med. Seater kh aoa etre cone acs Sree hte 55 
 - st a Be Moc Sa ety eG Bs win hk hee to ae Pe 60 
 cm Se nl 6 yon Sod GS ety cya eS opie We RRA Ee taate Sk 80 
 I e520 E I o. ) i. cc ee ee we ae eectaadvulecss 78 
 bi SOME Sti, she Sacha ts We Siad-whe pate aie hares 78 
 8 . LL ee 213 A RR Seo ae ee a 80 
 a Memes Mert ere ee Mat a Me ere ee Bae 82 
 ps “ Me VE ATI osc ao ane ake hd ws occ wade oe nk 87 
 NE ne i in cc bee da bee eee uaveun 70 
 Merteereseriicinl OCHre) .........0.cseccenecuvecscecbcces 65 
 MPT ICH IE. 2. cis. cw cc sees ew ccvudedanuvaceucs 71-73 
 Yellow Lake (Genuine Persian Berry).............eeceeee 30 
 Peteretiow (Basic Zinc Chromate).....5....0-..eeses000% 74 
 
 For this reason a special grinding liquid is generally employed. Pigment 
 concentration would vary according to the wetting power of the special liquid. 
 
 Note 7—This is straight orange mineral toned up with about 1% to 144% 
 of eosin. They are sometimes called French Vermillionette. 
 
 Note 6—Dry red toner and para and toluidin reds grind short in raw oil. f 
 
264 Oil Absorption Tests 
 
 GREENS 
 Chrome Green, Light... 26.0 @. ccus« ns 00 6 ese + eens gee 86 
 rD Medium a. sc tin oe oS One 85 
 Fg - Darks) ccccls Leis whe bah nage Oe 82 
 Chromium Oxide (Anhydrous) 3........%% 4. + «Sale» pee 88 
 
 (Hydrated), also known as Emeraude 
 Green, Vert de Guignet and Viridian.. 50 
 
 Yobalt Green (Genuine, Cobalt and Zine Oxide)........... 60 
 Emerald Green (Paris Green) .. 2... 00's «s+ belo 80 
 Green Lake (coal tar dye precipitated by means of phos- 
 pho-tungstic acid) <2... 0 .sh eve ewe nee s oe eo ee 40 
 Verdigris (Basic Copper Acetate) .... ....<1.es as eee 70-75 
 BLUES 
 Cobalt Blue (Genuine Cobalt Aluminate).................. 40 
 Prussian Blue (and Chinese)... i... 5% << « sw 5) «lhe eee 44-48 
 Ultramarine «i... sev ee bclen’s © bum sw oases ictee Ge one 43 
 Sublimed- Blue Lead =)... 32. eee eee oe 8 4 0 es ae eee 88 
 BROWNS 
 Brown, Metallic «444.75. e Lee ee er 78-80 
 Sienna, Burnt ...40.. 64 0% 6 o » ce is ew © ole acai ol wl ie ee 51 
 az FRO W «aie wn oes win 5 + clad ck oe utersun mW ce eee ee 50 
 Umber, Burnt oi. ec ois cp Wisle ee oe wore ole ig eee 52 
 Zs FRA W oo so ais is: tule 0 i Oni w wl cln'e: gimme ey lene eeataety ennn oz 
 Vandyke Brown . o. o0sstess che wes 8 ccna e «1b op tol cle 53 
 
 Or ABSORPTION OF VaRIoUS PIGMENTS* 
 
 100 lbs. of dry pigment requires the number of pounds of 
 
 raw linseed oil shown below to form a paste: 
 
 Basic Lead Carbonate... 5.06.46. 00s ces ss 0k eee 11 pounds 
 Basic Lead: Sulphate-icoeucank 2s oeae RP 11 
 Lithopone . 2.2... ewes bas ghee se wa seu 5 noise eee 25 ni 
 39% Leaded Zine... oc... 6 i sua vale 0 se Ulge lee ale lena 14 si 
 American Process Lead-Free Zinc.....5 +. <..00 a eee 25 ns 
 French 4 3 " fea bab ba oe ke Se 25 Ca 
 Titamox is os we coe Vv hw bu one eee ee eee ee mete aI ie 
 ©. P. Lemon Chrome Yellow..........4 -005 ., see 40 sy 
 C. P. Medium Chrome Yellow. ..:......0.... 35 . 
 C. P. Deep Chrome Orange....0.....0¢...15. 02 eee yao 6 
 C, P. Chinese Blue 1... ...005 S00 deen dec ces ca pee) ee 80 bs 
 C. P. Prussian Blue vy 2.05 ssa. cen pues «oc geey on eee 140 s 
 Ultramarine Blue . 2... 000.4405 0s sey eos Goa oe 45 = 
 C.P. Chromium Oxide .....2: 0021.0) .8400 15 ie 
 C. P. Light Chrome Green.......:..0.0:3+00e8 0 40 . 
 C, P. Medium Chrome Green; . 2: -..,4. 0.45...) 50 we 
 C. P. Deep Chrome Green... 2... ....+-50.s0c cue 60 i 
 25% Light Grinders Chrome Green... .........00 ee 30 os 
 25% Medium Grinders Chrome Green.......<...... ee 35 
 25% Deep Grinders Chrome .Green............)) so 40 4 
 C..P. Lithol Toner oso. ae eee 3a ee 120 
 Madder Lake 2... .5040005 ss un wleae ee oie one cle 160 sf 
 Bordeaux Maroon Lakes, ;.....¢s<<s0+sceecac se) 50 a 
 C. P. Light Para Toner... ¢. ...4.4 ene. waa AO sa 
 
 *Table furnished by A. F. Brown. 
 
 66 ee ees . 
 + a 
 
Oil Absorption Tests 
 
 265 
 
 Lene ee ———EEEEoEo—EEEEEEEEE——==us 
 
 SIE EM POMCT. .. 6. eee ew teeters tees ewrcnseens 150 pounds 
 10% Light Para Red on Calium Carbonate................ Se eaae SOG my 
 10% Deep « aa eae : ee eee Pe Vie er dese teh pith a: a one 35D i 
 eT a a vise eis tie ese ce bcos ee sew eeccee Pee af 
 PERMIT TTL sos ke see es RE ANE ee ET Cl ego. one ek are s-ahass fae tend) 40 * 
 momrier Lakes .....25.0...5- ae ee I ROE ee Peace Nee See OU “ 
 RINT TIGITIG PONCE. 2... ce ete eee eSNG Soc sa a a LOO 
 PUMICE EOI SALYLCS. 0c ce ce te te eee nee eee e seers 25 a 
 feminine on Calcium Oarbonate................0. eee eee . 60 " 
 CPN ONTOINALG. soe ek cee wees Se Se OE 3 aes, seh ee gay eae 2-40 As 
 
 FIGURE 93 
 
 Apparatus Required for Determining Oil 
 
 Absorption of Pigments 
 
266 Oil Absorption Tests 
 
 Fasig Oil Absorption Number.—kK. W. Fasig of The Lowe 
 Brothers Co., in commenting upon the Gardner-Coleman oil 
 absorption test, states that instead of using a spatula to mix 
 the pigment in oil, he puts the pigment in a mortar and grinds 
 it with a pestle. The oil is dropped into the mortar by means 
 of a burette. The end point is sharp. The advantage of this 
 method, according to Mr. Fasig, is that the results obtained 
 from the test can be used in actual mill practice. Thus, for 
 instance, in the case of zine oxide, he secured an oil absorp? 
 tion of 18 per cent. The same oxide, when ground to paste 
 form in actual mill practice, showed the presence of 82 per 
 cent of pigment and 18 per cent of oil. 
 
 Gardner-Coleman Oil Absorption Method.—In mixing a 
 pigment and a liquid a point is reached where independent of 
 such mechanical forces as could be developed by actual grind- 
 ing, the surface of each pigment particle is thoroughly wet 
 by the liquid and the pigment mass becomes thoroughly satu- 
 rated. This point represents the oil absorption property of 
 the pigment, and is expressed by a factor termed the oil ab- 
 sorption factor. This factor is therefore a measure of the 
 quantity of a given oil or liquid, required to thoroughly wet 
 all the absolute particle surface of the pigment mass. The 
 factor is ascertained by determining the number of cubic 
 centimeters of liquid required to saturate 20 grams of pig- 
 ment. It is then expressed as the amount required for 100 
 grams of pigment. 
 
 In designing a paint the oil absorption factor is especially 
 important. Thus if it is desired to increase the consistency 
 of a paint without increasing the percentage of pigment, high 
 oil absorbing pigments may be used. The opposite may be 
 accomplished by the use of low oil absorbing pigments. In 
 using high oil absorbing opaque pigments, inert pigments of 
 low oil absorption may be added in order to lessen the amount 
 of oil required to suspend the other pigments. When it is de- 
 sired to secure maximum opacity, regardless of other quali- 
 ties, a low oil absorption opaque pigment may be used. If a 
 
 glossy enamel-like finish is desired, a pigment of high oil 
 absorption is indicated. 
 
 The amount of oil required for pigment saturation or wet- 
 
Oil Absorption Tests 267 
 
 ting is directly proportional to the specific surface* of the pig- 
 ment mass, existing at the point of saturation. As the specific 
 surface of the mass is relative to its degree of particle sub- 
 division or fineness, it also measures to a great extent the fine- 
 ness of the pigment. The oil absorption factor being relative 
 to the surface conditions of the pigment is independent of its 
 chemical composition or specific gravity. The practical ad- 
 vantages of knowing the oil absorption factor le in the infor- 
 mation it gives concerning the following physical conditions 
 of the pigment: 
 
 (a) Relative amount of surface in the pigment mass. 
 
 (b) State of sub-division of the pigment particles. 
 
 (c) Comparative specific surface of various pigments. 
 
 (d) Variation in fineness or particle sub-division of various 
 lots of the same pigment. 
 
 The property of absorbing a given quantity of oil is relative 
 to the specific surface of the pigment mass. Thus the differ- 
 ence in oil absorption and body imparting property shown by 
 various pigments is due to the difference in specific surface or 
 particle sub-division. From this it follows that the variation 
 or difference in pigments in this respect exists up to satura- 
 tion point only: Beyond this point they all become uniform 
 in the amount of oil required to bring the mixtures to a cer- 
 tain consistency. This fact is important in the comparative 
 testing of pigments in liquid paints. The following is illus- 
 trative of its application. 
 
 If a series of pigments are ground into pastes on the basis 
 of the individual oil absorptions of each, and the same amount 
 of thinning mixture is then added to the same weight of each 
 dry pigment in its paste form (pigment plus oil required to 
 saturate), the resulting mixed paints, barring thickening due 
 to any chemical action, will be of practically the same con- 
 sistency. 
 
 Considerable information is also obtained by studying the 
 condition of the pastes at the oil absorption point. A very 
 considerable difference will be noted in the characteristics of 
 
 *It is believed that the oil absorption of a pigment may be reduced by 
 compacting. The small particles would then form aggregates and the specific 
 surface would be reduced, thus reducing the oil absorption. Similarly, by 
 effecting electrical changes in the particles to cause a coalescence or by 
 effecting a change in the surface tension of the particles, a reduction in oil 
 absorption might be accomplished. 
 
268 Oil Absorption Tests 
 
 the pastes produced by various pigments. Some pastes will be 
 short and tough. Others will be long, stringy and soft. Some 
 will have a high gloss. Others will present a dull appear- 
 ance. Some of the pastes will be dense, requiring heavy pres- 
 sure to flatten them out. Others will be soft and easily spread. 
 The amount of oil absorbed does not entirely control these 
 factors. In other words, two pigments of practically the same 
 oil absorption may yield entirely different types of pastes. 
 For example, one may be dense and the other soft. These 
 physical characteristics all indicate certain pigment qualities. 
 
 TABLE 46 
 Oil Absorption Factors on Some Pigments 
 Gardner-Coleman Method 
 
 Low-Oil High-Oil Average 
 Pigment. Absorption Absorption Type. 
 
 Type. Type 
 Basic Carbonate White Lead........ gs 22.0 ce 
 Basic Sulfate White Lead........... 26 32 30 
 Zine ONE Le ses 6 te ee eee 47.6 54.1 52 
 TAtaROX i xa eG bide oe oe eee 22 28 26 
 an Leaded’ Zine. 427.245 seen eee B13 36.5 ae 
 Lithopoue 3. ..cc on she oe eee ya Rees . BoD 33 
 Asbestine*:;.;.2.4. ts sie k saa eee ae 5O 50 
 RAPTYtOS 22045. WS 44 pee eee 13 15 13.5 
 Blane Wise. o:4255 4 takes ee ere 23 36 30 
 (Ghina Clay's) s0 dss Jove ce eee 41.5 53 > 51 
 GYDSUM. @ . Ss ei ee eee 26 eta 33.5 
 Siliea: (Crystalline }>.. {3.52 eee 20 . 28 23 
 Silica. (Amorphous) 2 io.0, eee ee 30 38 32 
 Pele 4. saw spe haa eee . 40 65 60 
 Writings 0. sig oct ote eee ee 28 35 32 
 
 The oil absorption point varies with different pigments and 
 is influenced by certain conditions. A pigment in its dry state 
 consists of individual particles and agglomerates of particles. 
 The particle surface and the mass particle surface combine to 
 make the absolute surface existing in a given volume of the 
 pigment. As the amount of oil required to saturate a certain 
 amount of pigment is the amount required to wet the absolute 
 particle surface, any influence which tends to change the sur- 
 face content (by changing the specifie surface) varies the oil 
 absorption point. Two common influences accomplishing such 
 change are found in the dispersion effect of certain vehicles, 
 and the effect of mixing and grinding pressure. While these 
 influences are always present to some degree in all paint mak- 
 ing procedure, the basis of the oil absorption factor should be 
 the condition of the pigment in its dry form with the elimina- 
 
Oil Absorption Tests 
 
 269 
 
 Gardner-Coleman Oil Absorption Results 
 
 TABLE 47 
 
 Raw Linseed Oil 
 
 Soya Bean Oil 
 
 Colloidal Condition 
 
 Oil 
 aaa Oil Ab Oil Ab 
 Ut AD- | Character | “1 4*°” | Character Oil Ab- | Character 
 Pees of Paste naa of Paste ee of Paste 
 Pipe Oxide 5. .0.::...0.. 54 Smooth. 53 Same as | 56.5 Glossy. 
 Glossy. with Smeary. 
 Quite Linseed Quite 
 long. Oil. rubbery. 
 Leaded Zinc 36.8 Soft. 35.5 Same as 39 Quite 
 Oxide (35%). with glossy. 
 Linseed Smeary. 
 Oil Rubbery. 
 Slightly 
 granular. 
 Lithopone (High 3135 Short. oy Same as 38 Fairly 
 Oil Absorption). Chalky with glossy. 
 Smooth. Linseed Long but 
 Oil. not 
 tough. 
 Slightly 
 granular 
 in ap- 
 pearance 
 Lithopone (Low | 25.5 Soft and 23:5 Same as 26 Very soft. 
 Oil Absorption). Long. with Runny 
 Fair gloss. Linseed and 
 Contains Oil smeary. 
 large Good 
 lumps. gloss. 
 Lumpy. 
 
 tion of these influences to as great an extent as may be pos- 
 sible. The oil absorption factor of all pigments is changed to 
 the same relative degree by the introduction of these influences 
 to an equal extent. 
 
 Certain oils and liquids, due to surface tension phenomena 
 or to such colloidal conditions as effect absorption or develop- 
 ment of great surface, tend to cause either a coalescence of the 
 pigment particles into particle agglomerates or by their dis- 
 persion effect, to break down the existing agglomerates and 
 disperse the particles into an extremely fine state of sub- 
 division. Hither of these conditions change the specific sur- 
 face of the mass and accordingly change the oil absorption 
 point. This variation in oil absorption with different oils is 
 
270 Oil Absorption Tests 
 
 illustrated by the following table, which gives the oil absorp- 
 tion factor of several pigments in linseed oil, in soya bean oil, 
 and in a liquid having a relatively high colloidal viscosity but 
 with an apparent viscosity approximately the same as the 
 other two. 
 
 Selection of Test Liquid.—In view of the results shown in 
 the above chart it is important that the oil used for determin- 
 ing the oil absorption factor be one that will have the minimum 
 effects in causing either a dispersion or coalescence of the pig- 
 ment particles. In such a vehicle the pigment tends to form a 
 mechanical suspension or mixture only. Thus the degree of 
 particle sub-division or agglomeration existing in the dry pig- 
 ment is retained to the greatest extent. Of the common and 
 available oils, raw linseed oil is the best suited for the pur- 
 pose. With most pigments it has but little dispersing or coal- 
 escing effect. It is therefore used as the standard vehicle for 
 determining the oil absorbing property of a pigment. If, how- 
 ever, it is desired to determine the oil absorption factor with 
 certain other liquids, the results will be relative to the dispers- 
 ing effect of the liquid used. In following the standard pro- 
 cedure a well settled Raw Linseed Oil, clear and free from 
 foots and having an acid value of from one to three should be 
 used. An oil of this kind is readily obtainable and easily kept. 
 A variation in the acid value of the oil affects the oil absorp- 
 tion point; the amount of oil required increasing with an in- 
 crease of the acid number. This difference is due either to a 
 greater particle dispersion or to a thickening caused by the 
 formation of soaps. It is important, therefore, that in mak- 
 ing determinations where very accurate results or close checks 
 are desired, that the oil used be always of the same acid value. 
 
 iE fect of Moisture on Test—The moisture contained in the 
 pigment, between certain limits, seems to play no important 
 part in the determination, since check results may be obtained 
 on portions of the same sample of pigment whether air dried, 
 
 oven dried or even slightly moist. Therefore, the ordinary | 
 
 air dried sample of commerce is in a satisfactory condition if 
 it does not contain sufficient moisture to cause it to mat to- 
 gether or cake. : 
 
 The temperature of the relatively small amount of oil used 
 during the operation is not important, because the oil is 1m- 
 mediately cooled by coming in contact with the much larger 
 
 ear an 
 
Oil Absorption Tests 271 
 
 mass of pigment. This statement is made with the assumption 
 that the oil is of the temperature prevailing in the ordinary 
 laboratory. When, however, the pigment is quite warm, the oil 
 absorption is shghtly decreased. This is due to the fact that 
 that viscosity of the oil is decreased by rise in temperature 
 and consequently the thickness of the. film with which it wets 
 the particles would be decreased. However, the difference 
 between 70° and 100° Fahrenheit, which is the average range 
 of a laboratory, is very slight so that the temperature need 
 not be taken into consideration except during extremes in 
 either way. 
 
 Principles to be Observed in Test.—The principle of this 
 test is that of effecting the wetting of all the ‘‘particle sur- 
 face’’ or ‘‘particle agglomerate surface’’ of the pigment mass 
 without the application of mixing or grinding pressure. This 
 is accomplished by certain oil addition and stirring procedure 
 as described herewith. In all stirring operations, care must 
 be taken not to cause mixing of the pigment and ‘oil by apply- 
 ing pressure, as this factor will tend to vary the results. All 
 stirring and mixing should be done very carefully and lightly. 
 A finger and wrist motion is all that should be used, allowing 
 the forearm to rest quietly. 
 
 When the oil first comes in contact with the pigment, a cor- 
 responding amount of particle surface is wetted. The par- 
 ticles thus wetted then coalesce or cling together and form 
 agglomerates or lumps of paste consisting of oil and pigment. 
 These small lumps of paste should be kept distributed through 
 the mass by stirring. As the absorption of oil by the mass in- 
 creases these lumps will mat together, forming larger lumps 
 or balls of paste. With further absorption of oil by the mass, 
 these larger lumps or agglomerates of oil and pigment paste 
 will coalesce and with most pigments will form one large ball. 
 (With a certain few pigments this large ball is not formed; 
 the separate smaller lumps remaining separated.) After this 
 point is reached a small amount of dry pigment may still be 
 left around the bottom and lower parts of the container. This 
 pigment is wet by bringing it in contact with the free oil exist- 
 ing on the surface of the large ball or lumps of paste. The end 
 point of the determination is reached when all of this dry 
 pigment has been taken up and wet. This point is indicated 
 by the following condition. While any dry unsaturated pig- 
 
272 Oil Absorption Tests 
 
 ment still remains, the paste will not smear on the glass. At 
 the point, however, where all of the pigment particles are wet, 
 the paste becomes soft and will smear on the sides and bottom 
 of the container.* The balls of paste may then lose their rig- 
 
 idity and tend to flatten out or lose their spherical form. This 
 
 point, which is very sharp, occurs within narrow limits and 
 is the end point. The apparatus required and method of test 
 are given below. 
 
 Burette.—A standardized burette should preferably be used. 
 If not standardized, the determinations should always be made 
 by starting with the same burette filled to the zero point. In 
 this way possible differences due to variation in the burette 
 graduation are largely eliminated. 
 
 Container for Mixing Pigment and Oil.—For this purpose 
 a smooth, round bottom jelly glass is very well suited. Those 
 
 having dimensions of approximately 2144 inches diameter at 
 
 top, and 314 inches deep are easily obtainable. Flat bottom 
 glasses or those having fluted sides or bottom should not be 
 used, as the pigment and paste tend to collect in the crevices, 
 making accurate determinations difficult. 
 
 Spatula—A blunt end, 4 inch, stiff blade spatula should be 
 used. If the blade is too limber, excessive stirring is required 
 and the results are liable to vary. 
 
 Preparation of Sample.—The sample to be tested should 
 first be placed in a suitable container (a small wide-mouth 
 bottle is adaptable) and well shaken so as to assure the elimi- 
 nation of any packed particles or lumps. This is especially 
 important if the pigment has been packed in barrels or other- 
 wise kept in a manner that is liable to cause it to pack to- 
 gether. If excessively moist, the sample should then be air 
 dried at room temperature. 
 
 Procedure.—Twenty grams of the pigment are placed in the 
 
 glass. The oil is then run in from the burette, either drop by 
 drop or with successive small additions. Either of these 
 methods will give check results. If the drop method is used 
 the rate of flow at the start should be about one drop per sec- 
 ond. If the small addition method is used, quantities of 1% ce. 
 should be added. As the absorption of the oil increases, the 
 
 *See Fig. 94. 
 
 ee == 
 
Oil Absorption Tests 273 
 
 rate of flow or quantity of the additions is decreased. This 
 is fully explained later. The oil is run in so as to strike the 
 dry pigment in the center. As the oil comes in contact with 
 the pigment, the dry pigment that has not been wet should be 
 lifted from the outer edge and placed over the oil so as to 
 bring all the oil surface in contact with the pigment. This is 
 best accomplished either by lifting it up on the spatula and 
 dumping it off on the oil, or very lightly throwing it over the 
 oil. ae 
 When the pigment particles become wet with the oil they 
 tend to coalesce and form small lumps of paste. These lumps 
 should be kept distributed throughout the mass. This is done 
 by lhghtly stirring the mixture of these paste lumps and dry 
 pigment in the manner of stirring described above, being care- 
 ful not to use pressure in the mixing. If the drop method of oil 
 addition is used this stirring should be carried on continuously 
 with the operation of bringing the dry pigment in contact with 
 the oil surface. If the successive addition method is used this 
 stirring should be done after each addition. As the absorption 
 of oil progresses these lumps of paste, by taking up more pig- 
 ment and matting together, form larger lumps which when 
 stirred around form balls. When this point is reached the 
 rate and quantity of the oil addition should be very much de- 
 creased and only a few drops added at a time. In adding the 
 oil at this point it should be allowed to strike on these lumps 
 and not on the remaining dry pigment. After each oil addition 
 these lumps are lightly stirred around so as to bring the oily 
 surface into contact with the remaining dry pigment. | 
 With further oil addition and stirring, these balls will with 
 most pigments join together and form one large lump, with but 
 little dry pigment remaining. With certain pigments, how- 
 ever, the lumps or balls of paste do not join together but re- 
 main separate and continue to collect more pigment. At this 
 point, which is close to the end point, the oil is added very 
 carefully, one or two drops at a time. With many pigments 
 one drop is all that is necessary to establish the end point. At 
 this stage, the oil should be allowed to strike on the surface of 
 the lump or lumps. They should then be worked around so as 
 to pick up more of the pigment. When all of the remaining 
 dry pigment has been picked up and wet, the end point is 
 reached. This is indicated as above explained by the paste 
 lump becoming much softer and easily spread with the spatula. 
 
274 Oil Absorption Tests 
 
 When stirred around it smears on the sides and bottom of the 
 glass. This end point is very sharp and occurs within narrow 
 limits. With most pigments only one or two drops of oil is 
 required to change the relatively hard dry lumps which do not 
 smear the walls of the container into a fairly soft paste which 
 will smear when stirred around. If, when the end point is 
 reached, the paste lumps are broken down or spread with the 
 spatula, it will be noted that the oil is uniformly distributed 
 throughout the mass and no dry pigment remains. 
 
 Different pigments have certain individual characteristics in 
 absorbing oil. These must be given consideration, and it is 
 sometimes necessary to slightly modify the procedure in order 
 to conform with these peculiarities. For example, some pig- 
 ments absorb the oil readily and in a uniform manner, while 
 others take up the oil slowly. The paste lumps of some are 
 smooth and free from hard agglomerates and are easily kept 
 uniformly mixed. Others tend to form hard lumps. With such 
 it is difficult to keep the mass uniform. When the end point is 
 reached with certain pigments, the paste lumps will be quite 
 firm. Other pigments will be firm up to the end point and then 
 suddenly become very soft; in some instances of semi-paste 
 consistency. These differences are largely due to certain 
 surface tension relations of the pigment and oil, a discussion — 
 of which is outside the scope of this chapter. A little experi- 
 ence with the various pigments will enable the operator to 
 
 effect such modifications as will be necessary to conform with 
 these conditions. 
 
 Close checks can be obtained on the test made in accordance 
 with the procedure explained above. Experienced operators 
 rarely vary more than 0.1 ce. in check tests or in tests conduc- 
 ted by different operators on the same sample. For ordinary 
 purposes a variation of 0.2 ec. is sufficiently close. A variation 
 of more than this amount on check tests can only be considered 
 as an error in the operation. In testing new pigments or 
 where a close determination is desired, two or more check 
 tests should be made. A little experience and a consideration 
 of the following previously stated precautions is sufficient to 
 insure accurate results: 
 
 (a) The pigment must not be moist. 
 (b) It should be well shaken before making the test. 
 
 _(¢) It should not be of a temperature lower than 70° or 
 higher than 100° F. z 
 
Oil Absorption Tests 275 
 
 (d) The oil should be well settled and of a standard acid 
 value. | | 
 
 (e) The oil should not be added too fast, nor should it be 
 added slower than is necessary. 
 
 (f) The mixture should only be stirred enough to keep the 
 mass uniform and bring the pigments in contact with the oil. 
 
 (g) Excessive stirring tends to lower the result. 
 
 (h) The stirring should be done lightly and care taken not 
 to use pressure or endeavor to mix the pigment and oil by this 
 means. 
 
 (1) When nearing the end point, the oil should be added 
 slowly and in small amounts (one or two drops at a time). 
 
 FIGuRE 94 
 Pigment Mass Just Before Pigment Muss at Point of Satura- 
 Point of Saturation. Mass is tion. Mass Loses Its Spherical Form 
 Spherical and Does Not Mark and Smears Glass. 
 
 Glass. 
 
CHAPTER XVII 
 TEXTURE OF PIGMENTS 
 
 The property which many pigments exhibit in readily dis- 
 persing and becoming finely divided when mixed with a liquid, 
 even without grinding, is due to a quality termed ‘‘texture.’’ 
 This term is used to designate the structure of the pigment, 
 and bears no relation to its fineness. As there has been some 
 confusion among paint manufacturers regarding the applica- 
 tion of the terms of ‘‘texture’’ and ‘‘fineness,’’ the following 
 definitions and discussion are given. A comparison of them 
 will serve to show their proper application and import. 
 
 Texture —‘Texture. By extension, the peculiar disposition of the con- 
 stituents parts of any body—its make, consistency, etc.; structure in gen- 
 eral, as the texture of rocks, the mode of aggregation of the mineral sub- 
 stances of which rocks are composed. It relates to the arrangement of their 
 parts viewed on a smaller scale than that of their structure. The texture of 
 rocks may be compact, earthy, granular, scaly, slaty, ete.” (Century Diction- 
 ary.) And the attributes of texture: “Hard, Solid and firm to the touch; 
 firm in substance and texture, so as not to be readily altered in shape, pene- 
 trated, or divided; so constituted as to resist compressing, penetrating, 
 dividing or abrading action; opposed to soft.” (Century Dictionary.) “Soft. 
 Yielding readily to pressure ; easily penetrated ; impressible; yielding; opposed 
 to hard; easily susceptible of change of form. (Century Dictionary.) 
 
 Pinatas mae Consisting of minute particles, grains, drops, flakes, etc.” 
 (Century Dictionary.) And its opposite characteristic, coarse. “Coarse- 
 grained, consisting of large particles, fibres or constituent elements.” (Cen- 
 tury Dictionary.) 
 
 From the above definitions it is apparent that the terms 
 ‘coarse’’ and ‘‘fine’’ refer to the extent of the subdivision of 
 
 the particles constituting a mass. They are quality terms and 
 are subject to the determination of degree of either property 
 by measurement of the size of the particles. 
 
 The terms ‘‘hard’’ and ‘‘soft’’ (which are the attributes of 
 texture) are quality terms and relate to the character of the 
 mass or of the particles of which it consists. They are in this 
 sense relative terms and as such are determined in degree by 
 comparison and by such means as will indicate differences 
 sharply. Fineness, then, relates to the degree to which the 
 particles have been subdivided, and texture to the character 
 of the particles, independent of their size. As applied to pig- 
 ments, the important properties and the most desirable from 
 a general paint-making standpoint are maximum fineness and 
 soft texture, although there are certain exceptions to this, such 
 
Texture of Pigments OBA 
 
 as the use of hard pigments in wood fillers and in small 
 amounts in certain mixed paints. 
 
 From this it will be seen that pigments of equal fineness may 
 differ greatly in texture of a similar texture may vary in their 
 degree of fineness. Closely related to the texture of a pigment 
 are, ease of grinding, character of finish, settling and harden- 
 ing in the package, and to some extent flowing and spreading 
 of the paint. A pigment of soft texture disperses more read- 
 ily, grinds more easily, produces a smoother finish, has less 
 tendency to settle and harden, and makes a better flowing and 
 spreading paint, than one of hard texture. 
 
 The test described herewith for determining the compara- 
 tive texture of pigments has been widely used by certain man- 
 ufacturers and found valuable as a method for setting stand- 
 ards and in investigation work. It is based on the extent to 
 which pigments under certain conditions will disperse in a 
 liquid having good dispersing properties. The liquid used is 
 a mixture of equal parts by volume of blown linseed oil of a 
 specific gravity of approximately .945 to .950 and pure turpen- 
 tine. This mixture should be of slightly higher viscosity than 
 raw linseed oil. If on account of age or storage in open tanks 
 the blown oil has become heavy, a further addition of turpen- 
 tine should be made so as to bring the mixture to the proper 
 consistency. It should be strained through silk or very fine 
 cloth before use. 
 
 Apparatus Required—Ground or frosted glass plate about 
 one foot square. Several clear glass plates 4” x 4” or 4” x 6”. 
 Three-inch glass muller. Artist’s spatula (4” blade). Small 
 spatula. 50 cc. beaker. It is important that the small glass 
 plates be thoroughly washed with soap and water, and then 
 with alcohol so as to remove all dirt and grease from the sur- 
 face. If a soft cloth is used for drying the washed glass, it 
 should be first washed in alcohol, and dried, so as to free all 
 loose particles of lint. 
 
 Method of Making Determination.—12 ce. of the liquid de- 
 scribed are used with from one to two grams of pigment. The 
 amount of any pigment used depends on its oil absorption. 
 With high oil absorbing pigments such as zine oxide, high oil 
 absorption lithopone, asbestine, china clay, and similar pig- 
 ments, one gram is sufficient. With medium oil absorption 
 pigments, such as low oil absorption lithopone, whiting, silica, 
 
278 Texture of Pigments 
 
 ee nn ORG 
 etc., one and one-half grams are used. For pigments of low 
 oil absorption, such as basic carbonate or basic sulphate white 
 lead, barytes, etc., two grams are used. As the test is only 
 qualitative and largely comparative, a closer calculation than 
 the above, based on oil absorption, is not important. 
 
 The pigment is mixed to a thin semi-paste on the ground 
 glass plate with about lec. of the liquid. This paste is then 
 well rubbed out with the muller in three mulling operations 
 for one minute each. This is done by mulling the paste con- 
 tinually for one minute, then scraping it up to a pile on the 
 
 FIGuRE 95 
 
 Photomicrograph of paint of good texture flowed 
 on glass. Note fine particles. 
 
 plate. This operation is carried out for the third time. The 
 purpose of this mulling is to break down the particle agglo- 
 merates of the pigment and to cause each particle to become 
 wet with the liquid. A light pressure in mulling, sufficient to 
 thoroughly rub out the paste, is preferable to a heavy grinding 
 pressure. 
 
 It has been found that mulling to the extent stated is suffi- 
 cient to practically eliminate any variation in results, although 
 further mulling, even with more pressure, does not materially 
 
 ee ee ee ee ee ey ee a 
 
 ee ee ae 
 
Texture of Pigments 279 
 
 affect the results. Between each mulling operation, a few 
 drops of the liquid should be added in order to compensate 
 for evaporation or thickening condition. 
 
 After the mulling is completed, thin the paste with a further 
 amount of the liquid and transfer to the beaker. Add the bal- 
 ance of the liquid, and stir thoroughly. Let stand for one or 
 two minutes to eliminate the air. Then pour the mixture on a 
 clean glass plate, holding the plate in an almost vertical posi- 
 tion and pouring the Peat across the upper portion so that it 
 will flow down. Place the plate in a vertical position so that 
 
 ae s >i - i 
 Bit oiiatlon oe . 
 
 FIGURE 96 
 
 Photomicrograph of paint of poor texture flowed 
 on glass. Note coarse particles. 
 
 the excess will drain off. It should be left in this position un- 
 til the film is dry. 
 
 In this test the pigment particles of soft texture will become 
 so finely divided that they are either collodially dispersed or 
 so finely dispersed as not to be visible to the eye. The harder 
 particles which have not been finely dispersed show up. As 
 the mixture flows down the plate, the smaller particles remain 
 at the top in the thinner part of the film while the larger par- 
 
280 Texture of Pigments 
 a 
 
 ticles as well as pieces of lint and dirt flow down to the lower 
 part of the plate and can be easily observed in this portion of 
 the film. 
 
 ~ Interpretation of Results——Some pigments disperse easily 
 and to a great extent, while others contain many small and a 
 
 few large particles which do not readily disperse. Others con- 
 
 tain a majority of large particles. A comparison of different 
 pigments or different lots of the same pigment will serve to 
 show their character in this respect. 
 
 ~ Liquids also vary in their dispersing property. Some will 
 disperse pigments to a greater extent than others. Certain 
 liquids may with certain pigments have the opposite effect— 
 that of causing some pigments to agglomerate and form large, 
 hard particles. This test may therefore be used to determine 
 the relative dispersing properties of paint hquids. For this 
 purpose any one pigment may be tested with several liquids 
 in the manner described, and comparisons made. 
 
CHAPTER XVIII 
 
 MISCELLANEOUS PHYSICAL TESTING DEVICES AND 
 METHODS 
 
 There is presented below a description of some miscellane- 
 ous apparatus and methods of test which have been used to 
 advantage in testing various coating materials. 
 
 Testing Printing Effects upon Films.—One of the principal 
 advantages of a nitrocellulose lacquer is its property of rapid 
 drying. It is difficult, however, to state how soon a laequer is 
 sufficiently dry to withstand packing and shipping without 
 showing printing. An apparatus used at the Parlin plant of 
 the du Pont Company for this purpose is shown herewith, in 
 Pip. | 
 
 FIGURE 97 
 
 Print Testing Device. 
 
 It consists of a wooden base on which are mounted two fixed 
 standards between which is fastened a bar which can be ad- 
 justed to the thickness of the panel to be tested. The remov- 
 able levers carrying weights are graduated. 
 
 After a definite drying time the panel is placed on the base; 
 any suitable coarse material such as cheesecloth or burlap is 
 dampened and laid on the lacquer, and the weight adjusted to 
 the desired magnitude. The test is allowed to run for a defi- 
 nite length of time, generally about 6 hours at the end of which 
 the panel is examined for the print or impression of the cloth. 
 
282 Miscellaneous Physical Testing Devices 
 a ea 
 
 Testing Impact Effects upon Films.—An instrument used at 
 the Parlin plant of the du Pont Company for measuring the re- 
 sistance to shock of an enamel or lacquer is shown herewith. 
 This instrument has apparently proved very satisfactory for 
 determining the elasticity or adhesion under the conditions 
 of the impact. 
 
 FIGuRE 98 
 
 Impact Testing Machine. 
 
 The apparatus consists of two parallel standards one of 
 which carries a scale, and between which is a fixed anvil. 
 Resting on this anvil can be seen a panel to be tested. The 
 tool for impacting the panel equipped in this ease with a ball 
 bearing tip, passes through a fixed rung a few inches above the 
 anvil. Above the rung is a movable hammer which may be 
 dropped through any desired distance using a suitable weight, 
 making various types of impact depending on the position of 
 the panel, and the nature of the tool employed. 
 
Miscellaneous Physical Testing Devices 283 
 
 —$—S —$————— 
 The photograph shows a group showing the various tools 
 which may be used in getting different types of impact as 
 well as a panel which has been tested with the ball bearing 
 impactor. It will be noticed that impacts have been made 
 from the underside of the panel as well as directly on the 
 lacquer. In other words, some of the depressions are concave, 
 
 FIGURE 99 
 
 Impact Testing Device in Operation. 
 
 others convex with respect to the coated side of the panel. 
 The concave impacts, i. e. where the impact has been made 
 directly on the coating, give, as well as resistance to shock, a 
 measure of the adhesion of the enamel; while the convex 
 impacts, i. e. those made on the under side of the panel, meas- 
 
284 Miscellaneous Physical Testing Devices 
 
 ure the elasticity, or the ability of the enamel to stretch around 
 the protrusion made by the tool under the conditions of the 
 impact. 7 
 
 The resistance to impact is measured quantatively by 
 scraping off the loosened enamel with a spatula, and measur- 
 ing the diameter of the exposed portion, thus facilitating com- 
 parisons between products of different compositions. 
 
 Methods of Tésting—To make an impact test, place the 
 panel in the position shown in the photograph, 1. e. resting be- 
 tween the anvil and the impacting tool. Raise the hammer 
 through the desired distance, usually 20 inches, and release. 
 Reverse the panel and follow the same procedure. When sey- 
 eral tests have been made, examine as described above. 
 
 Testing the Discoloration of Interior Whites.—The simple 
 form of cabinet shown in the illustration was designed for use 
 in testing the ‘‘yellowing’’ of interior paints and enamels. It 
 
 | ZZ LLGL DDL DLA MM 
 
 | ‘ TT UIT} Sa i 2 Ls Zs 
 | eee hi ies ce i i 
 lt Tl 
 Hu Ltn, ts = 
 LT ili 
 2 HA 
 
 Figure 100 
 Dark Chamber, i 
 
 Gardner Color Change Cabinet. 
 
Miscellaneous Physical Testing Devices 285 
 
 is made of galvanized iron with a double walled air space in 
 the center. The sides and tops are provided with air ducts 
 and holes for thermometric readings. At the bottom of each 
 chamber, a shallow pan containing several sheets of blotting 
 paper is placed. An ounce and a half of water is added to 
 each pan and readily absorbed by the paper. This amount 
 is usually sufficient to provide high humidity of the atmos- 
 phere in the white chamber for a period of 12 hours and in the 
 dark chamber for 30 hours. The entire inner surface of one 
 chamber is coated with flat black and the other chamber with 
 flat white. The white chamber is furnished with electrical 
 connections and a 75-watt blue Daylo Mazda lamp which simu- 
 lates ordinary noon daylight. A 10-foot length of insulated 
 wire is provided for plugging into any convenient electric 
 light socket. When the lamp is lighted, the temperature in 
 the white chamber will run from 48° C. (118° F.) to 56° C. 
 (132° F.), at various points, whereas the black chamber will! 
 show approximately 28° C. (82° F.). 
 
 Application of Black Cabinet.—A series of metal, wood or 
 other types of slats are coated with white paint, dried, and 
 then exposed in the black cabinet. The warm, humid atmos- 
 phere will quickly develop differences in the colors. In two 
 days’ time a loss of reflection of about 6 per cent has been no- 
 ticed in one type of paint, due to yellowing of the oil content. 
 Marked differences in such a short period have also been no- 
 ticed in various types of marketed industrial paints and ena- 
 mels. In a longer period much more discernible results may 
 be noticed. It is believed that these results may be compara- 
 ble to what would occur to paints in a very much longer time 
 when exposed on factory walls. 
 
 The addition of a small amount (5 per cent) of ammonia 
 water to the water used in the pan in this cabinet will greatly 
 accelerate the yellowing of the paints. 
 
 A pplication of White Cabinet.—Paints containing pigments 
 that are easily fogged by strong sunlight may, after proper ex- 
 posure to the bombardment of transmitted and reflected light 
 rays, be affected to some slight extent in the white cabinet. 
 The paints may be applied to panels and exposed in the eabi- 
 net, or the pigment under examination can be rubbed up with 
 a normal quantity of the liquid in which it is to be used in 
 paint. This may then be spread upon a panel and dried. Half 
 
286 Miscellaneous Physical Testing Devices 
 
 of the surface may then be covered with black paper. Daily 
 examination of the panels, until a difference is noted in the 
 covered and uncovered portions, will be instructive. Similar 
 tests may be made on organic colors that may be easily af- 
 fected by light. It should be remembered, however, that the 
 light from a Daylo Mazda lamp is extremely mild as compared 
 to that from an ultro-violet arc; the latter giving effects in a 
 few minutes that are not obtainable over a long period of 
 time by other means. ‘The white cabinet described above may, 
 therefore, be of but little use when a quick test for fogging is 
 desired. The writer is, however, endeavoring to arrange a 
 cabinet with an extra compartment provided with an iron 
 are rich in ultra-violet rays. 
 
 Corrosion.—lither cabinet may find some application in de- 
 termining the comparative corrosion resistance of metal pan- 
 els. The temperature and high humidity should give notice- 
 able results. Similarly it may be used for determining the 
 rust-inhibitive properties of pigments. In the latter case the 
 pigment is mixed to a thin paste with water and applied to a 
 small area on a brightly polished steel surface. After expos- 
 ure for forty-eight hours, the test plates are removed, the pig- 
 ment washed off, and the area formerly covered by the pig- 
 ment examined for signs of rusting or etching. 
 
 Testing the Insulating Value of Coated Pipes.—The type of 
 
 a aS 
 ane 
 Pa 
 
 oy <0 oy <9 
 th it~ 
 
 Figure 101 
 
 Moisture Condensing From Atmosphere Upon Surface of Coated and 
 Uncoated Pipes. 
 
 P 
 
Miscellaneous Physical Testing Devices 287 
 a 
 apparatus used by the writer to determine the insulation value 
 of protective coatings upon pipes carrying water and liquids 
 of low temperature, is shown in Fig 101. If such pipes are ex- 
 posed in warm rooms, beads of water may appear upon the 
 surface, due to condensation of moisture from the atmosphere. 
 In the illustration, the large container shown is filled with ice 
 water which flows down through the two lateral pipes. One 
 pipe may be left bare and the other painted. After drying, 
 the tests may be applied for a period of 30 minutes to deter- 
 mine the relative value of the coatings. 
 
 Testing Paints of High Luminosity to Reduce Refrigeration 
 Losses.—During the summer months, surfaces painted in dark 
 colors rapidly absorb heat rays and become very hot. When 
 white paints are used, the painted surfaces are slow to absorb 
 heat rays and consequently will be found many degrees cooler. 
 An application of this principle might well be made to con- 
 Serve ice and keep refrigerator cars and ships at a tempera- 
 ture sufficiently low to preserve perishable foodstuffs for a 
 longer period. At the present time, refrigerator cars are usu- 
 ally painted an orange color, while refrigerator ships are gen- 
 erally painted battleship gray. Both of these colors rapidly 
 become warm and transfer their warmth to the compartments. 
 Losses in ice and foodstuffs may result. White or hght tints 
 of paint should be adopted for both of these carriers. 
 
 In the test apparatus constructed by the writer, a double 
 wall effect was obtained by placing a pint container inside a 
 quart container. Ground cork (about 1/16 to 1/8 inch in dia- 
 meter) was filled in between. The exterior surface of the 
 outer container was painted in two-coat work, each with a 
 different color. Several containers were thus prepared and 
 filled at the same time with a low temperature refrigerating 
 liquid. The hquid used was ice water in one instance, and a 
 Solution of solid carbon dioxide gas in acetone in another in- 
 Stance. The latter had a temperature of -40° C. Closely ecom- 
 parable results were obtained with these two liquids. Cracked 
 ice was also experimented with, but it was found diffeult to 
 obtain uniform temperatures in each can because of the diffi- 
 culty of transferring the ice in exactly equal quantities with- 
 out loss of temperature. 
 
 After placing the liquids in the inner cans, the covers, which 
 were provided with stoppers and thermometers, were adjusted 
 
288 Miscellaneous Physical Testing Devices 
 
 Se 
 and a layer of cork spread over the upper surface. The outer 
 containers were then sealed at the top. A row of the vari- 
 colored containers was placed out of doors in the sun, and 
 thermometric readings made every minute. At the end of 
 
 A RES OS OS Ae ee Be ab a roe LL Lh LD 
 wet “A 
 7 
 
 edn Oe ans pea 
 FIGURE 102 
 
 Inner container for refrigerating liquid. Cork 
 
 air insulation. Outer container painted in 
 
 various colors. Thermometer provided for low 
 temperature work. 
 
 thirty minutes, the black cans could not be handled because of 
 their high temperature (140° F.)* The white cans could be 
 handled comfortably, indicating a much lower temperature. 
 Later experiments with white metallic pigment powders indi- 
 
 * On the roof of laboratory at Washington, Aug. 6, 1924. 
 
Miscellaneous Physical Testing Devices 289 
 
 cated that they do not give as efficient results as a white paint, 
 but superior results to most tinted or colored paints. 
 
 The rapid transfer of heat apparently took place from the 
 outer can through the layer of ‘cork-and-air’? insulating 
 space, and then tough the inner can into the liquid. This 
 transfer of heat was very rapid, as is shown by the tempera- 
 tures recorded at the end of thirty minutes. It is Ste ae 
 
 AN 
 
 RISE IN TEMPERATURE DEGREES CENTIGRADE 
 
 ee 
 Zon 
 ales 
 Paley) 
 oes 
 ea) 
 
 TIME IN MINUTES 
 i FIGURE 103 
 
 Chart showing comparative rise in temperature of liquid in cans 
 painted different colors. 
 
 that much greater differences might be shown at the end of 
 six or eight hours time on a freight car in a sunny yard or even 
 in transit. Convection might, however, play an important 
 feature in the latter instance. 
 
 The results obtained in these tests would suggest the use of 
 white or light tints of paints rather than dark colors, on re- 
 frigerator cars or ships. 
 
 Testing the Temperature of Colored Building Materials. — 
 The temperature of the interior of structures in Summer 
 months and of the materials of construction in general, will 
 depend to a marked extent on the color of the exterior surface. 
 Most uncoated structures will be warmer in the Summer 
 months than structures painted in white or light tints. This. 
 principle is recognized in tropical countries where structures 
 are usually white. Some experiments just completed show 
 
290 Miscellaneous Physical Testing Devices 
 
 [ji 
 the difference in temperature of the air in metal containers 
 painted with different colors. The tests also included wood 
 panels about 84-inch thick, 4 inches wide and 6 inches long; 
 iron panels 34-inch thick, 2 inches wide and 4 inches long. 
 Thermometers were inserted deeply into the ends of these pan- 
 els. In the metal containers the thermometer readings were 
 
 TEMPERATURES OF SOME BUILDING MATERIALS 
 
 Air in Metal Interior of Interior of 
 Structure wood panel iron panel 
 Not Painted ows ees ea eee 102°F. 114°F., 126°F. 
 Painted ~ “White p24. akiaoatee oe 102 104 106 
 Painted “Creams <faien ¢2ecee. 103 110. 110 
 Painted.-Aluminuni.,..46445 0084 104 114 114 
 Painted - OrdngenJe . eae. ee eee 107 118 118 
 Painted Hed Tice sce eee 108 126 122 
 Painted: Gray cc. a dssats secs cle aie 110 122 120 
 Painted) Bites ear hs oe aia en 108 120 122 
 Painted Green ei isa Coe ee 109 124 126 
 Painted. Bleek. 36s oak eee ee 114 130 130 
 Concrete Slabs ...s.a. tate 108°F. 
 Concrete Slab Painted White 102 
 Red Brick... anst6ee ee eee 114 
 Red Brick Painted White..... 96 
 
 made 14-inch from the bottoms and in the center. All panels 
 
 were exposed on the roof of the laboratory on a day when ~ 
 
 official temperature of the air was 82° F. The highest tem- 
 perature recorded in any of the experiments was 130°. On 
 one day during the Summer, the temperature of the air was 
 106° F., and on that day the black panel registered 140° F. 
 
 The wide difference in temperature of the uncoated and 
 eoated red brick is of great importance and would indicate 
 the advisability of painting red brick dwellings. The paint- 
 ing of such buildings would not only reduce the temperature 
 in Summertime, but would probably be of benefit in the Win- 
 ter months, because of the possible insulating value of the 
 paint in preventing the heat from getting outside. Moreover, 
 painted bricks are not as porous as unpainted bricks. Driv- 
 ing rain storms cause the absorption of large amounts of water 
 in a brick surface. To demonstrate this, tests were made on 
 unpainted and painted bricks of the same type. These were 
 immersed in water for a period of one hour. The gain in 
 weight in water of the two is shown below: 
 
Miscellaneous Physical Testing Devices 291 
 
 Brick Before Soaking....... 1968 Grams 
 itiek iter Soaking ....... 2198 
 Begins Water)... 2.405. 230 Grams 
 Painted Brick Before Soaking 2022 
 Painted Brick After Soaking. 2032 
 Perr ater .. 6c... oS. 10 Grams 
 
 Testing Film Thickness as Affected by Speed of Withdrawal. 
 When articles to be coated with japan or pigmented enamels 
 and similar products are immersed in the coating medium and 
 then withdrawn, the thickness of film deposited will vary with 
 the speed of withdrawal. Thus, for instance, if the object is 
 withdrawn rapidly, a thick film will be applied. As a rule, 
 if the object is withdrawn slowly, a thin film will be applied. 
 
 Some preliminary tests to determine the thickness of films 
 applied to small sheets of glass withdrawn at different speeds 
 are described below. In the experiments, a black baking 
 Japan and a green baking enamel were employed. These were 
 reduced to various consistencies with two different kinds 
 of thinning materials, namely, mineral spirits and painters’ 
 naphtha (petroleum benzine). The mineral spirits employed 
 met the specifications of the Federal Specifications Board, 
 Standard Specification No. 16, U. S. Government Specifica- 
 tion for Volatile Mineral Spirits for Thinning Paints (Bureau 
 of Standards Circular No. 98). The painters’ naphtha or ben- 
 zine employed had the following boiling range: 
 
 EE EP OEAVITG 6. os soc ns a os so cc ee ducacccccs 62° C. 
 NS aA SES a a re 106° C. 
 
 0 y Re te rt AP ia beng och oe ni dae ay 
 30% ‘ RN ss aetiee eae et ony. wel Ges cx 25°C 
 40% a BURR Cea any ne a EGA elie scl e 133° C 
 50% ef Rr Ae het ay ets ee eae 2 oe 141° C 
 
 0 re soca ORR A ge 3 Neat NANG 9 De a ae ea 149° C 
 70% 2 tere ths i we etic ale Es Sa kk wks 157° C 
 80% = MP eel ae rd clomid MOR gk kare con 166° C 
 90% Zi eer. oR Ae i tans fee wie 179° C 
 ee 5 PE. eke tes oboe ven ceeenc., 206.7° C 
 
 The reductions made were as follows: 
 Mineral spirits 
 
 Green baking enamel or benzine 
 
 75 parts by weight 25 parts by weight 
 66 TS 66 66 : 83 66 6 66 
 60 66 66 66 40 66 66 66 
 
 66 6“ 66 66 6é 6e 
 50 50 
 
292 Miscellaneous Physical Testing Devices 
 
 18.0 
 wo el LLL hve 
 
 Ne TT 
 SMoataees = 
 ate NUT 
 sole | NU 
 Sool _| NSE 
 5 ot | Me 
 Sool fea A a eS] 
 Soest! | 1 | SEE 
 8 ole eX 
 yo aoe 
 5 eo foam TT 
 Se 
 st LLL ee 
 a 
 LLL 
 oC LEE 
 
 LEE 
 OG ste ae 8. 10 l2 14 16 18 2OSRe ee eoee 
 
 6 
 DIPPING TIME IN SECONDS 
 90 I8 9 
 INCHES PER MINUTE 
 
 | FIGURE 104 
 
 Results On Green Baking Enamel. 
 
 oO) 
 
 The rates of withdrawal were: 
 90 inches per minute 
 18 66 os 6s 
 9 6é 
 6 es 
 After coating and draining for one hour, the panels were 
 
 baked at 150° C. for 8 hours. Thickness determinations were 
 then made with an Ames micrometer which is calibrated in 
 
Miscellaneous Physical Testing Devices 293 
 
 1/100 of amillimeter. The panels were of glass, 3 inches wide 
 and 8 inches in length. Lines were drawn 34”, 114”, and 21,” 
 from the side after coating. Starting one inch from the bot- 
 tom of each line, the thickness was measured every successive 
 inch to the top of the panel. The average of these was taken 
 as the average thickness of the film. The results are plotted 
 in Fig. 104. | | 
 
 Volume and Weight Cup.—F or determining the weight of a 
 gallon of paint, many laboratories use a 100 ce. flask or brass 
 eup. This laboratory has found it most convenient to use the 
 
 il 
 =, 
 7 rr9s 
 
 FIGURE 105 
 
 latter. One was made with a section of a brass tube, threaded 
 at the end, and fitted with a removable threaded bottom, and 
 a ground glass cover. The removable bottom makes it easy 
 to clean the apparatus. The ground glass cover permits ac- 
 curate filling, being used to level off the excess material. The 
 
294 Miscellaneous Physical Testing Devices 
 
 net weight of the contents divided by 100 gives the specific 
 gravity of the paint. Since the specific gravity of water is 1, 
 and one gallon of water weighs 8.33 lbs., the weight of a gallon 
 of the material under consideration is 8.33 times the specific 
 gravity of the product. Thus, for example, a paint was weighed 
 and found to weigh 222. grams, which divided by 100 gives a 
 figure of 2.22 specific gravity. This specific gravity, namely, 
 2.22 multiplied by 8.33 equals 1814, or the weight per gallon of 
 the paint. 
 
 If one of these is made up to contain one gill of liquid in- 
 stead of 100 ce. of liquid, the weight of the paint in grams 
 would be multiplied by 0.0705 to give the pounds per gallon, 
 and by 0.00845 to give the specific gravity. 
 
 Panel Racks for Baking Tests.—At times it is necessary to 
 run a large number of baking tests on coated panels which are 
 
 a en a SS a ae en ee : 
 SRR OR 
 SSS eS SSS: Ath EOI SE BENE 
 
 een 
 
 SR Ce EE ASR 
 
 ea PE ER ER TER a ee 
 = Se aN y SR SRC UU 
 RANT OO . Poo a A a A SS a eee 
 
 rer SS, SE, SE, WG, E.G, WE, ,G. 
 eae ere Serene re rere wen icone ceca ay 
 
 a SN RGA GASA EA SRE eR Ree eR ee 
 
 q RES. GS SR VR OE Spoke i RR ES SR, GRR. CRG “in TE 
 CAQAY RES SR SSS SSS SEES SSS 
 
 SSS RRS TT 
 
 \ SS SS enn ese 
 SEAVER SEROUS GER, SEAS OU SUDHA, SUA SUAS 'SHA.UR,'SUNLEL.TUEL.TOnOm tone 
 
 Jy SSS SSS SSS SSS 
 SRR CP, GE, EO, NA “Hee were Ue. Se, SR 
 
 =e 
 [SSSA SSSA, SUR SSO SO WH, VOR SUN'S 'VU Wn, WON, Wana Wann UU "Oun, wun.ouneaneanea oes 
 
 FIGURE 106 
 Rack for Panels to be Baked for Kauri Gum Reduction Test. 
 
 to be bent to determine the kauri reduction of the finish. This 
 laboratory has found that a set of shelves made of quarter- 
 inch mesh wire cloth is very convenient for that purpose. The 
 construction of these shelves is shown in the illustration. Fig. 
 106. The shelf shown will hold 24 panels. It is placed in a 
 
 a a 
 
Miscellaneous Physical Testing Devices 295 
 
 hot water oven wherein the temperature is quite uniform 
 throughout. ‘The panels are baked for 5 hours, as given 
 in the specifications for this test. They are then removed, 
 cooled, and bent over a mandril, and examined. 
 
 A Rack for Draining Panels.—In coating small tin panels 
 in the laboratory with varnishes for the determination of 
 drying time, and hot and cold water tests, it is desirable to 
 have some sort of drainage pan where the excess material will 
 drain off without smearing the laboratory tables. This labo- 
 ratory has constructed a rack which is shown in Fig. 107. The 
 size of the pan is 6x18x2 inches. Supported by the sides of 
 the pan are four small racks in which the coated panels are 
 placed, leaning against wire frames or supports. As the ex- 
 cess material drains off the panels, it drips down into the bot- 
 tom of the pan through openings. By the use of this pan, 
 
 FIGURE 107 
 
 Drip Pan for Drying Panels. 
 
 the panels can be all kept in one place of fairly constant 
 temperature. If desired, the pan with a set of coated panels 
 may be carried to any room where constant temperature or 
 humidity prevails. 
 
 Brush Cleaning Device.—A simple type of brush cleaning 
 device is shown in the illustration below. It consists of a 
 metal pan over which is stretched quarter-inch mesh wire. 
 Brushes may be given a rapid preliminary ‘‘wiping off’’ upon 
 
296 Miscellaneous Physical Testing Devices 
 
 this apparatus. It has been found quite useful in the paint 
 testing room. 
 
 Wat 
 Stas 
 
 RATS OS 
 \, LS 
 
 FIGgurRE 108 
 
 Brush Wiping Device. 
 
 Papers on Physical Testing.—The following list of techni- 
 cal papers relating to the physical testing of paint and varnish 
 products is submitted for those who care to make a complete 
 study of the subject. 
 
 Optical Properties and Theory of Color of Pigments and Paints—H. BE. 
 Merwin. Proc. Amer. Soc. Test. Mater. XVII—Part II, 494. 
 
 Determination of Absolute Viscosity by the Saybolt Universal and Engler 
 Viscosimeters—Winslow H. Herschel. J] bid., 551. 
 
 The Standard Saybolt Universal Viscosimeter—Winslow H. Herschel. 
 Ibid., XVIII—Part II, 363. 
 
 The Variable Pressure Method for the Measurement of Viscosity—E. C. 
 Bingham. Jbid., 373. 
 
Miscellaneous Physical Testing Devices 297 
 
 Paint, a Plastic Material and aa a Viscous Liquid: the Measurement of 
 its Mobility and Yield Value—E. C, Bingham and Henry Green. Jbid., XIX— 
 Part II, 640. 
 
 An Instrument for Measuring the Hiding Power of Paints—R. L. Hallett. 
 Ibid., XX—Part II, 426. 
 
 a New Colorimeter for White Pigments and Some Results Obtained by 
 Its Use—A. H. Pfund. Jbid., 440. 
 
 Further Development of the Plastometer and its Practical Application 
 to Research and Routine Problems—H. Green. Jbid., 451. 
 
 Stress-Strain Measurements on Films of Drying Oils, Paints and Var- 
 nishes—H. A. Nelson. Jbid., XXI, 1111. 
 
 The Use of Secondary Reference Standards in Process Problems of Color 
 Measurement—H. S. Busby. Jbid., 1139. 
 
 Relation of Yield Value and Mobility of Paints to Their so-called Painting 
 Consistency—J. EH. Booge, E. C. Bingham, and H. D. Bruce. Jbid., XXII. 
 
 Some Physical Properties of Paints—P. H. Walker and J. G. Thompson. 
 Ibid., XXII. 
 
 Accelerated Weathering of Paints on Wood and Metal Surfaces—Harley 
 A, Nelson. Jbid., XXII—Part II, 485. 
 
 An Analysis and Comparison of Systems of Color Measurement and Some 
 Notes on Interchangeability in Color Measurement—H. S. Busby. Jbid., XXII. 
 
 An Application of the Pfund Colorimeter.to the Determination of Tinting 
 Strength—J. A. Calbeck. Jbid., XXII. a 
 
 Hiding Power of Paints—R. L. Hallett. Jbid.. XXII. Jbid., X XVI, 538. 
 
 The Study of Nitrocellulose Lacquers by the Stress-strain Method—G. W. 
 Rundle and W. C. Norris. Jbid., XX VI—Part II, 546. 
 
 Mechanical Testing and Recording of the Drying of Paints and Var- 
 nishes—John Mc. Sanderson. Jbid., XXVI—Part II, 556. 
 
 Accelerated Weathering: Further Development of Apparatus and Exposure 
 Cycles—H. A. Nelson, F. C. Schmutz and D. L. Gamble. Jbid.,. XXVI—Part 
 IT, 563. 
 
 Further Studies of the Physical Properties of Drving-Oil. Paint and Var- 
 nish Films—H. A. Nelson and G. W. Rundle. Jbid., XXIII—Part IT, 356. 
 
 Some Optical Properties of White Paint Pigments in the Ultra-violet Spec- 
 trum—A. H. Pfund. J/bid., XXIII—Part II, 369. 
 
 The Effect of Certain Paint Films on Ultra-violet: Light—R. L. Hallett. 
 Ibid., XXITI—Part II, 379. 
 
 Color—G. W. Thompson. Jbid., XXIII—Part IT, 396. 
 
 Symposium on Consistency. Jbid., XXIII—Part II, 482. 
 
 Further Study of Accelerated Weathering Effect of Variations in Exposure 
 Cycle Combinations on Common Types of Varnishes—H. A. Nelson and F. C. 
 Schmutz. Jbid.. XX1IV—Part II, 920. 
 
 A Relative Method for Determining Particle Size of Pigments—G. Be Ac 
 Stutz and A. H. Pfund. Ind. and Eng. Chem. 19, 51. (1927.) 
 
 The Relation of Yield Value to Particle Size—Henry Green and George 
 S. Haslam. Ind. and Eng. Chem. 19, 53. (1927.) 
 
 Particle Size and Distribution by Sedimentation Method—J. H. Calbeck 
 and H. R. Harner. Ind. and Eng. Chem. 19, 58. (1927.) 
 
 The Testing of Paint Pigments for Transparency to Ultra-violet Radia- 
 tion—G. F. A. Stutz, Jour. Frank. Inst. 203, p. 89. (1926.) 
 
 A Photometric Method for Measuring the Hiding Power of Paints—H. D. 
 Bruce. Tech. Paper of the U. S. Bureau of Standards No. 306. 
 
 Reflection Curve in Color Specification—F. P. Ingalls. J. W. Masury & Son, 
 ‘Brooklyn, N. Y. Paint, Oil and Chemical Review, October 21, 1926. 
 
 Report of Sub-Committee XVIII on Physical Properties of Paint—F. P. 
 Ingalls and M. Rea Paul. Paint Manufacturers’ Association of the U. 8S. 
 Special Circular, Scientific Section, Educational Bureau, September, 1926. 
 
 Color Measurement: A Method Giving Direct Reading of Color Inde- 
 pendent of Color Vision of the Observer—Carl W. Keuffel, Keuffel & Esser Co. 
 Paint, Oil and Chem. Review, Vol. 82. No. 5, July 29, 1926. 
 
 Notes on Color Measurement— Carl W. Keuffel, Keuffel & Esser Co. Official 
 “a Federation of Paint and Varnish Production Clubs, Vol. 47, Janu- 
 ary 
 
298 Conversion Tables 
 
 Conversion Tables 
 
 Note.—The figures in bold-face type refer to the quantity 
 which it is desired to convert from one system to the other 
 system. If converting from the system in the right-hand 
 column, the equivalent in the other system will be found in 
 the left-hand column, while if converting from the system in 
 the left-hand column, the equivalent in the other system will 
 be found in the right-hand column. For example, 1 inch = 
 2.040 em. and 1 em. = 0.3937 inches. 
 
 Cm. Inches Inch 
 2.540 1 0.3937 1000 Microns 
 5.080 2 0.7874 0.03937 1 25.4 
 7.620 3 1.1811 _ 0.07874 2 50.8 
 10.160 4 1.5748 0.11811 3 76.2 
 12.700 5 1.9685 0.15748 4 101.6 
 15.240 6 2.3622 0.19685 5 127.0 
 17.780 y | 2.7559 0.23622 6 152.4 
 20.320 8 3.1496 0.27559 | 177.8 
 22.860 9 3.5433 0.31496 8 203.2 
 25.400 10 3.937 0.35433 9 228.6 
 27.940 11 4.724 0.3937 10 254.0 
 30.480 12 5.512 
 Ounces Grams 0S in: C. C. 
 0.03527 ah 28.350 0.06102 1 16.387 
 0.07055 Pe 56.699 0.12204 2 32.774 
 0.10582 3 85.049 0.18306 3 49.161 
 0.14110 4 113.398 0.24408 4 65.548 
 0.17637 5 141.748 0.30510 5 81.935 
 0.21161 6 170.097 0.36612 6 98.322 
 0.24692 4 198.447 0.42714 q 114.709 
 0.28219 8 226.796 0.48816 8 131.096 
 0.31747 9 255.146 0.54918 9 147.483 
 0.35274 10 283.50 0.61023 10 163.872 
 0.38801 11 311.85 
 0.42328 12 340.20 
 0.45855 13 368.55 
 0.493882 14 396.90 
 0.52909 15 425 25 
 0.56430 16 453.60 
 Pints Liters Gallons Liters 
 2A18 1 0.47317 0.2642 1 3.785 
 4.226 2 0.94634 0.5283 2 rRiyel 
 6.339 3 1.41951 0.7925 3 11.356 
 8.452 4 1.89268 1.0567 4 15.141 
 10.565 5 2.36585 1.3209 5 18.927 
 12.678 6 2.83902 1.5850 6 Pa te B 
 14.791 7 3.31219 1.8492 y | 26.497 
 16.904 8 3.78536 2.1134 8 30.262 
 19.017 9 4.25853 2OiG 9 34.068 
 21.134 10 Apa Len 2.6417 10 37.853 
 
 eg 
 
 Ce ae : 
 bey 2 poll Sart ey Ral, 4 
 a eae hh 
 
Conversion Tables 299 
 
 sq. in. Cm?, 
 
 0.1550 1 6.452 
 
 0.3100 2 12.903 
 
 046003. ~-°719.355 
 
 0.6200 4 25.806 
 
 0.7750 5 32.258 
 
 0.9300 6 38.710 
 
 1.0845 7 45.161 
 
 TiZoue~ 82 01.615 
 
 1.3949 9 58.064 
 
 1.5499 10 64.516 
 
 TEMPERATURE 
 C. F. C. F. cot  ghs Ge F. 
 —17.8 Oeeaeioc.co 38° 100.4| 24.4 76 168.8)110 230 446 
 —17.2 T 38-8| 3.89 39 102.2) 25.0 Tie 110.6116 240 464 
 —16.7 2 35.6) 4.44 40 104.0) 25.6 78 172.4121 250 482 
 —16.1 Brat.4\°>.00 41 ~ 105.8) 26.1 79 = 174.2|127 260 500 
 —15.6 Beeede.2ib.06.° 42. 107.6} 26.7 80 176.0/132 270 518 
 —15.0 Seas 06.11 43 . 109.4) 27.2 81 177.8/138 280 536 
 —14.4 Weepae.s) 0.07, 44. 111.2) 27.8 82 179.6143 290 554 
 —13.9 fees. Cl 1.22 45° 113.0) 28.3 83 181.4/149 300 Biz 
 —13.3 8 46.4) 7.78 46 114.8) 28.9 84 183.2/154 310 590 
 —12.8 Gee4as.c| S.00 47 116.6) 29.4 85 185.0/160 320 608 
 —12.2 10 50.0) 8.89 48 118.4} 30.0 86 186.8/166 330 626 
 —11.7 Bigpor.5) 9.44 49 120.2) 30.6 87 188.6)171 340 644 
 —11.1 12 58.6/10.0 50 = 122.0} 31.1 88 190.4|177 350 662 
 —10.6 13. 55.4/10.6 Bite 23.3) Olt 89 192.2/182 360 680 
 —10.0 04 57.2111. 52 125.6/'32.2 90 194.0)188 370 698 
 9.445 15 59.0/11.7 540! 127 A|- 32:8 91  195.8])193 380 716 
 6.59. 16° 60.8/12.2 54 129.2) 33.3 92 197.6/199 390 734 
 — 6.59 17 62.6/12.8 Sho 151.0) 33.9 93 199.4|204 400 752 
 7.15 18> .64.4/13.3 56 =. 1182.8} 34.4 94 201.2/210 410 770 
 s=722 19 66.2/13.9 57 «134.6. 35.0 95 203.0/216 420 788 
 == 6.67 20 68.0/14.4 58 1386.4) 35.6 96 204.8/221 430 806 
 == 0.11. 21 69.8/15.0 59> 2138.2) 36.1 97 206.6|227 440 824 
 98-56. 22)! 71.6/15.6 60 140.0) 36.7 98 208.4/232 450 842 
 == p.00 23  73.4|16.1 61 141.8} 37.2 99 210.2/238 460 860 
 = 444° 24° 75.2/16.7 62 148.6) 37.8 100 212.0)2438 470 878 
 epee 25° 77.0117.2 63 145.4) 43 110 2380 |249 480 896 
 = 8.06 26 78.8/17.8 64 147.2) 49 120 248 |254 490 914 
 ite 27. 80,6118.3 65 149.0] 54 130 266 |260 500 932 
 =—2.22. 28 82.4/18.9 66 150.8] 60 140 284 |266 510 950 
 e—1i-01 29  84,2/19.4 67 152.6} 66 150 302 |271 520 968 
 ott. 30. 86.0/20.0 68 154.4] 71 160 320 (277 530 986 
 — 0.56 31 87.8/20.6 69 156.2] 77 170, 3381282 540 1004 
 0 32° 89.6/21.1 70 =158.0} 82 180 356 |288 550 1022 
 Woo as 91.4/21.7 71 = 159.8) 88 190 374 |293 560 1040 
 eb 34.198 2122 2 T2- 21.61 -61.938 200 392 |299 570 1058 
 1.67 35 95.0/22.8 73 163.4] 99 210 410 |304 580 1076 
 2.22 36 96.8/23.3 74 165.2/100 WAZ Als 1310 590 1094 
 2.78 37 98.6/23.9 75 167.0}104 220 428 /|316 600 1112 
 
CHAPTER XIX 
 
 TESTING WHITE OPAQUE PIGMENTS FOR SOME PHYSICAL 
 PROPERTIES (ROUTINE METHODS) 
 
 Color.*—Approximately 5 grams of the sample shall be 
 thoroughly mixed with the smallest quantity of bleached lin- 
 seed oil that will produce a smooth paste. This paste shall 
 be spread on a palette of colorless plate-glass in a smooth and 
 even layer, that will not transmit light and is at least 1 inch 
 by 3 inches in area. 
 
 An equal amount of the standard (or each of the standards) 
 shall be prepared in the same way, care being taken to bring 
 the paste to the same consistency as the sample being tested. 
 This paste shall be spread in a similar manner on the palette 
 beside the sample, touching it, and the two compared in dif- 
 fused daylight. In doing so, the palette shall be titled so that 
 the light will strike the surface of the pastes at different 
 angles and the under surfaces shall also be observed through 
 the glass. 3 
 
 In doubtful cases, only the sample and one standard may be 
 spread on the palette at the same time, and their edges must 
 touch. paaye 
 
 To be on-grade, the sample must be as white as the standard. 
 
 Brightness.*—Five grams of the sample and 1.20 grams of 
 bleached linseed oil shall be mixed to a smooth, uniform paste. 
 The oil used may be determined by dropping from a point 
 which has been standardized by counting the number of drops 
 necessary to weigh 1.20 grams. The dropping shall be at a 
 rate not greater than 70 drops per minute. All the sample and 
 all the oil must be thoroughly incorporated. This paste shall 
 be spread on a palette of colorless paste-glass in a smooth and 
 even layer that will not transmit light and is at least 1 inch 
 by 3 inches in area. 
 
 When the nature of the pigment requires more oil than 
 above noted, more shall be used but comparisons shall be made 
 only between samples which have a like oil-vehicle ratio. 
 
 An equal amount of the standard shall be prepared in the 
 same way. This paste shall be spread in a similar manner on 
 
 * Palmerton Laboratory Method. 
 
Testing White Opaque Pigments 301 
 
 the palette beside the sample, touching it, and the two com- 
 pared by observing in diffused daylight the two samples by 
 looking through the glass. 
 In doubtful cases, only the sample and one standard may be 
 spread on the palette at the same time, and their edges must 
 touch. | 
 
 To be on-grade, the sample must be equal to or better than 
 the standard in brightness or brilliancy. 
 
 Smoothness and Freedom from Specks.—Approximately 5 
 grams of the sample shall be thoroughly mixed with the small- 
 est quantity of bleached linseed oil that will produce a smooth 
 paste. This paste shall be spread on a palette of colorless 
 plate-glass in a smooth and even layer that will not transmit 
 light and is at least 1 inch by 3 inches in area. 
 
 An equal amount of the standard shall be prepared in the 
 same way, care being taken to bring the paste to the same 
 consistency as the sample being tested. This paste shall be 
 spread in a similar manner on the palette beside the sample, 
 touching it, and the two compared in diffused daylight. In 
 doing so, the palette shall be tilted so that the light will strike 
 the surface of the pastes at different angles. 
 
 In doubtful cases, only the sample and one standard may be 
 spread on the palette at the same time, and their edges must 
 touch. 7 
 
 To be on-grade, the sample must contain no more granular 
 or foreign matter than the standard. This is to be determined 
 by the feel under the knife and the amount of noise made in 
 rubbing down and by observation of the surfaces after the 
 pastes have been spread on the palette. 
 
 Tinting Strength.—F ive grams of the sample, 0.5 grams of 
 ultramarine blue and 1.20 grams of bleached linseed oil shall 
 be mixed to a smooth, uniform paste of uniform color through- 
 out. ‘The oil used may be determined by dropping from a 
 point which has been standardized by counting the number 
 of drops necessary to weigh 1.20 grams. The dropping shall 
 be at a rate not greater than 70 drops per minute. The mixing 
 shall be done by rubbing lightly with a spatula whose blade 
 is not over 5 inches long. All the sample, blue and oil must 
 be thoroughly incorporated. This paste shall be spread on 
 a palette of colorless plate-glass in a layer that will not trans- 
 mit light. 
 
302 Testing White Opaque Pigments 
 
 The standard shall be prepared in the same way and spread 
 in a similar manner on the palette beside the sample, touching 
 it. : 
 
 Another standard paste shall be prepared by mixing 9.5 
 grams of the standard, 0.5 grams of ultramarine blue and 1.82 
 grams of bleached linseed oil in the same way and spread in a 
 similar manner on the palette beside the sample, touching it. 
 
 In doubtful cases, only the sample and the two standards 
 may be spread on the palette at the same time and the sample 
 must be in contact with both standards at the edges. 7 
 
 To be on-grade, the sample must not be darker than the 
 first standard and not lighter than the second standard when 
 observed through the glass. 
 
 Palmerton Test for Settling of White Pigments in Water.— 
 This test shall be made in a flat-bottomed glass tube of 11/16 
 inch diameter, 6 inches height and uniform bore. ‘T'wenty- 
 seven cc. of water should fill it to a height of 434 inches with 
 an allowable plus or minus variation of 1/16 inch. 
 
 Five grams of the sample shall be put into the tube after 
 the latter is half filled with water. The product and water 
 shall be well mixed with a piece of wire about 14 or 12 gauge 
 and the tube filled with water to a height of 484 inches. The 
 wire is to be removed and washed off in the process of adding 
 this water. ‘The tube shall then be shaken vigorously 80 times, 
 the thumb being held over the opening in the top. After shak- 
 ing, it shall be placed in a rack so that it stands vertically and 
 the height of the column of the product measured at the end of 
 1, 2, 3 and 24 hours. 
 
 An equal amount of the standard shall be treated in the 
 same way. 
 
 To be on-grade, the height of column of the sample must be 
 within 10 per cent plus or minus of the height of column of 
 the standard at the end of 24 hours. 
 
 Croll Method for Grading Tinting Strength of White Pig- 
 ments.—Weigh from one to five grams of the official sample 
 of white pigment and for each gram of white pigment, weigh 
 twenty milligrams of C. P. Chrome Green. Transfer to a 
 clean, smooth glass or stone plate and add a measured amount 
 of Refined Linseed Oil in sufficient quantity to produce a stiff 
 paste, when oil and pigment are thoroughly mixed with a flat 
 glass muller or with steel spatula. After thoroughly mixing 
 
Testing White Opaque Pigments 303 
 
 to a stiff paste, add several more drops of Refined Oil and 
 mix thoroughly to a smooth paste, which can be readily spread 
 on a glass plate in a liberal ‘‘smear.’’ Treat standard sample 
 and shipment sample identically alike in this test; that is, use 
 the same equipment, size of sample and amount of oil, and 
 spread standard sample on a palette in a smooth ‘“smear,”’ 
 sufficiently thick to cut off transmitting light. Have standard 
 ‘‘smear’’ and shipment sample spread out side by side in 
 actual contact on glass palette. In grading for tinting 
 strength, examine the sample in bright diffused day light (not 
 direct sunlight) and accept shipment for tinting strength if 
 the shipment sample is as light or lighter in color than the 
 standard sample. If the standard sample is lighter in color 
 than the shipment sample, the material does not meet the 
 specification. | 
 
 TINTING STRENGTH (Barton Method) * 
 
 Preparation of Special Lampblack.—Mix thoroughly by 
 milling in a dry state in a porcelain Jar mill 6 parts precipi- 
 tated calcium carbonate with 1 part lampblack. 
 ___ General Method.—Mix the sample and the indicated amount 
 
 of tinting pigment with refined linseed oil by rubbing for three 
 minutes with a spatula on a glass plate, using such a quantity 
 of oil as required to make a stiff plastic paste which adheres 
 well to the glass and works easily without breaking. Then 
 add enough more oil to make a mixture containing 80 to 90 
 per cent by volume of oil, and rub for two minutes. 
 
 Compare the tinting effect with that of a standard tint, 
 made by similarly mixing a standard pigment and tinting pig- 
 ment with oil to paste form and then reducing to 80 to 90 per 
 cent oil by volume. The tinting strengths are practically 
 
 proportional to the amounts of black required to give identical 
 tints. 
 
 Determination of Tinting Strength of Titanium Oxide— 
 Weigh one gram of Standard Titanox (labeled ‘‘Titanox Tint- 
 ing Strength Standard, Niagara Falls, August 7, 1920 Pint 
 ing Strength 350’) and .1225 gram of Special Lampblack 
 onto an 8’’x8’’ ground glass plate. Add .25 gram (12 drops 
 from special burette) of refined linseed oil, and mix for three 
 
 *L. E. Barton, Titanium Pigment Co., Niagara Falls, N. Y. 
 
304 Testing White Opaque Pigments 
 
 minutes with a flexible spatula. Make a further addition of , 
 1.25 grams of oil (60 drops from special burette) and mix for 
 two minutes longer. The standard, thus prepared, has a tint- 
 ing strength of 350 as compared to a Standard White Lead 
 
 taken as 100. 
 
 The sample of Titanium Oxide to be compared with the 
 Titanox is prepared by similarly mixing one gram of pigment 
 and the estimated quantity of Special Lampblack (usually 
 about .35 gram, corresponding to 1000 tinting strength) with 
 88 gram (42 drops from special burette) of refined linseed 
 oil and then reducing the resulting paste by the further addi- 
 tion of .77 gram (37 drops from special burette) of oil. 
 
 The sample is now compared with the Standard by placing 
 portions of the paint side by side and in contact with each 
 other on a microscope slide. The samples are placed upon the 
 slide by allowing one drop of each to flow from the spatula 
 and fall upon the slide so that the drops will flow together. 
 This method of applying the sample gives a uniform spread 
 which is judged by turning the slide over and viewing through 
 the glass. | 
 
 If the sample is found to be of lighter tint than that of the 
 Standard, add a greater weight of Special Lampblack to a 
 new sample. If it is darker, add a lesser weight of Lampblack 
 until the tint matches that of the Standard. Always prepare 
 a fresh sample for each trial, mixing in the regular way. 
 
 Determination of Tinting Strength of Titanox and “*C’™* 
 Pigments.—The determination of tinting strength of Titanox 
 and ‘‘C’’? Pigments is made as described for Titanium Oxide, 
 except that the oil additions are as shown in the following 
 tabulation: 
 
 1st Oil Eq. Drops 2nd Oil Eq. Drops 
 Addition from Spec. Addition. from Spec. Total Oil 
 
 grams Burette grams Burette grams 
 Titanium Oxide... =. 88 42 ef if 4 37 1.65 
 Titanexe oa. as Ce ae 145 12 1.25 GOs, 1.50 
 CP SPIO Men Sie ae 4 16 1.66 79 2.00 
 
 * Calcium Sulfate Base Titanox. 
 
CHAPTER XX 
 
 TESTING COLORS FOR TONE AND STRENGTH 
 
 Generally speaking pigment colors are bought on physical 
 tests rather than chemical analysis. While it is true that the 
 knowledge of the exact chemical composition of a color may be 
 desirable for certain uses nevertheless the value and suit- 
 ability of colors for most purposes can be quickly determined 
 by physical tests for overtone and strength, and while making 
 these tests, the relative oil absorption, texture, etc., can be 
 noted. Suggestions made by A. F. Brown are included below. 
 
 In testing for overtone and strength it is absolutely essen- 
 tial that certain fundamental principles be observed, other- 
 wise, the tests of two given samples will be misleading. The 
 common practice of weighing roughly a given amount of color, 
 then adding a certain number of drops of oil and rubbing an 
 indefinite length of time with a spatula is likely to result in 
 erroneous conclusions. Not only is it necessary that the dry 
 color be accurately weighed, but the vehicle should also be 
 weighed. Two colors ground in different vehicles should never 
 be compared, as different vehicles produce different effects 
 with the same color. Sufficient vehicle should always be used 
 so that when the color has been rubbed and applied to a strip 
 of glass, or tin, the surface’ has a high gloss. In comparing 
 the overtones of two colors, if it so happens that one sample 
 has higher oil absorption than the other, sufficient additional 
 oil should be used with the color having the higher oil absorp- 
 tion to produce a paste of about the same consistency, other- 
 wise the comparison will be misleading. 
 
 The amount of dry color used in making tests depends upon 
 the type of color and the oil absorption. For C. P. Blues and 
 C. P. Para and Toluidine Toners 0.5 grams of color is suffi- 
 cient, while for C. P. Chrome Greens, C. P. Chrome Yellows, C. 
 P. Oranges and all reduced colors, one gram of dry color is 
 not too much. The proper amount of vehicle is dependent 
 upon the oil absorption and the type of vehicle used. Experi- 
 ence has shown that where colors are to be used for certain 
 purposes such as enamels, tests are more comparable to fac- 
 tory practice if rubbed in a viscous non-volatile medium such 
 as a polymerized linseed oil about the consistency of 00 htho 
 
306 Testing Colors for Tone and Strength 
 
 varnish, instead of raw or refined linseed oil. Ina general way 
 the proper proportion of dry color to vehicle is as follows: 
 
 TABLE 48 
 
 Polymerized Linseed Oil 
 Raw Linseed Oil (00 litho varnish ) 
 Gram color Gram oil Gram color Gram oil 
 
 Cte Tron. Biies cc agutes eee ao i acy 6 
 CAP Para: Toner, vee cae are eae ma) 8 b 8 
 GUE -Toluidine yponet ye. .-wa es oo 6 na) 8 
 C.P. Chrome Green Light..... 1.0 i 1.0 3 
 C.P. Chrome Green Medium.... 1.0 6 1.0 + 
 C.P. Chrome Green Deep...... LO or 1.0 5 
 iP. Chrome Yellow. ick ees as 1.0 4 1.0 4 
 C.P Chrome -Orangesivignc ss seu 1.0 oe 1.0 3 
 teduced Chrome Greens....... 1.0 “ou 1.0 3 
 
 In weighing, it is desirable to use balanced watch glasses 
 counterbalancing the sample against the standard with which 
 it is to be compared; the dry colors being first weighed and 
 then the vehicle which is placed shghtly away from the color. 
 With a little care, no trouble will be had in transferring the 
 mass to the rubbing slab. Some operators prefer to add the 
 oil from a burette, each drop of raw oil being assigned a defi- 
 nite weight. Bodied oils, however, could not be accurately 
 weighed by such a method. The Brown burette (see page 259) 
 for use in oil absorptions is suitable for delivering raw linseed 
 oil in exact amounts. 
 
 The materials should be very carefully transferred to the 
 rubbing slab. Plate glass about 24 inchs by 24 inches that has 
 been lightly sandblasted (such as can now be obtained from 
 any chemical glassware supply house) serves very well as a 
 rubbing slab, and a glass muller with a 214 inch face is about 
 the right size. The color and vehicle are first mixed with a 
 spatula until there are no dry particles of color, then the re- 
 sultant paste rubbed with the glass muller a definite number 
 of times, care being taken to exert the same pressure on both 
 samples so that the relative development will be exactly the 
 same. 
 
 The number of times a color should be rubbed depends upon 
 the type of color and the actual factory practice as regards 
 development. In some factories colors are well ground, but in 
 many ostensibly efficient plants it is surprising how little at- 
 tention is given to securing the maximum money value by 
 complete development. In a general way the number of 
 
Testing Colors for Tone and Strength 307 
 
 ‘rubs’? necessary to secure development equivalent to aver- 
 age factory practice is as follows: 
 
 TOT IES. 6. oc ens ce ete te eect e serene 300 times 
 Mt ara PONCTS. 6. oc nc epee sete tener eee e ns 300 times 
 Were oliiminie “TONCTS. 2. sew ee ee ee ee eens 300 times 
 @, P. Chrome Greens... 1... - cece cece ese eeees 150: times 
 er wohrome YellOwWS.......2.0.0ssccc ces eceeees 50 times 
 Reduced Colors, all kindS.............eseeeeeeees 50 times 
 
 rE Ss sale ts ale igisle nob ose cee Fess oss 200 times 
 
 In rubbing, the muller should traverse a space about three 
 ‘nehes wide and twelve inches long, the operator pushing the 
 muller up one side and down the other side of this strip so that 
 all the color particles receive the same amount of attrition 
 every rub. By one rub is meant one complete movement up 
 and down. In testing a color which requires twenty-five rubs 
 the color should be scraped up after fifteen rubs and then 
 rubbed another ten times; when testing a color requiring more 
 than twenty-five rubs the color should be scraped up with a 
 spatula after each twenty-five rubs. After the rubbing 1s 
 completed the comparison for overtone should be made by ap- 
 plying liberal portions of each color to glass.or tin in juxta- 
 position. The larger daub of color the better, but in any event 
 each daub should not be smaller than a half-dollar and they 
 should be placed in juxtaposition, care being taken that the 
 edges just touch but do not overlap and that there is a well de- 
 - fined line of demarcation. After being so placed and before 
 comparing, a wide spatula should be lightly drawn over both 
 at the same time to produce a color surface that will be smooth 
 and free from ridges. In comparing for overtone, the colors 
 should not be examined through the glass. For this reason 
 strips of tin are preferable to glass as it effectively prevents 
 this practice. If the colors are to be used for inks, this test 
 may be made upon bond paper. Observation of the stained 
 paper when held to the light will show whether the color is 
 clear, bright or muddy. 
 
 For making strength tests, it is well to have a stock paste 
 of zinc oxide in oil. Such a paste can be made by grinding 185 
 parts of zine oxide and 115 parts of OO litho oil several times 
 through a roller mill. A strength test can then be quickly 
 made by taking a small amount of the paste color made as 
 outlined above for comparing the overtone and adding the 
 proper amount of zinc oxide paste. 
 
308 Testing Colors for Tone and Strength 
 
 For reduced colors a reduction of 20 to 1, i. e., 20 parts zine 
 oxide paste to 1 part paste color, is usually sufficient but for 
 C. P. colors a 100 to 1 reduction is necessary to get the proper 
 idea of relative strengths. Very often two C. P. colors which 
 apparently are about the same strength on a 20 to 1 reduction 
 are very far apart on a 100 to 1 reduction. In making the re- 
 duction test the best way is to counterbalance 100 milligrams 
 of the two paste colors to be tested and then add to each, two 
 grams of the paste zine oxide. Before removing from the 
 counterbalanced watch glasses mix the color with the zinc 
 oxide, using a small spatula thus minimizing the loss on trans- 
 ferring, then remove from watch glass to a smooth piece of 
 glass and mix with a spatula until the color no longer streaks, 
 which indicates that it is thoroughly incorporated. Never make 
 a strength test on a rough glass and do not rub with a muller, | 
 as this develops strength that is not secured in factory prac- 
 tice. In the event that a 100 to 1 reduction is desired, take 500 
 milligrams of the first reduction, add 2 grams of zine oxide 
 paste and proceed as before. 
 
 If it is desired to express quantitatively the tinting strength 
 of the color, consider the standard color as having a tinting 
 strength of 100, and then vary the amount of the standard 
 color until the tints are matched. | 
 
 For example, let the amount of standard color for 100 strength test be 
 0,029.) (= "47, Vary this amounts in units of 5 per cent, thus 0.019 or 
 0.021. Let the amount taken to match a given strength = B, then 
 
 A . 
 — 100 
 RB’ 
 
 equals the tinting Strength of the sample to be tested. 
 If the tone varies it may be difficult to make this measurement. 
 
 The comparison for overtone should be made as soon as the 
 colors have been applied to the strip of glass or tin, otherwise 
 ‘‘flooding’’ may result in one or both samples and there will © 
 be no basis for comparison. 
 
 Generally speaking, it is good practice to have separate rub- 
 bing glasses for each of the four general classes of color— 
 greens, yellows, blues and reds to avoid contamination of one 
 color with another. If one glass is used for all colors, great 
 care must be exercised to insure absolute cleanliness. It is 
 surprising, for instance, how little chrome green is required 
 to off-shade a primrose yellow. Benzol 90° is probably the 
 best liquid for cleaning the rubbing glasses. 
 
CHAPTER XXI 
 ACCELERATED TESTING CABINETS 
 
 Accelerated tests on paint and varnish films, through the 
 use of ultra-violet light, artificial rainstorms, and low and 
 high temperatures, have received much attention during the 
 past three years. The importance of securing in three weeks’ 
 
 lh 
 
 : 
 
 | 
 | 
 
 i 
 
 FicgurE 109—Cabinet recently designed and installed at writer’s laboratory. 
 
310 Accelerated Testing Cabinets 
 
 time information that might require a year in ordinary roof 
 exposure tests can readily be appreciated. Even though the 
 results of such accelerated tests may not follow exactly those 
 obtained by exterior exposure tests, they may guide the in- 
 vestigator in determining the comparative life of certain coat- 
 ings. Probably the first cabinet built to make tests on panels 
 of fair size, that would afford means of a real study of the 
 problem, was that designed by H. A. Nelson, who has kindly 
 prepared a highly instructive resume of his important work, 
 which appears on page 326. 
 
 FIGURE 110 
 
 Photographic view of Cabinet showing size as compared to observer. 
 
 The writer and H. C. Parks recently designed and installed — 
 an apparatus which subjects panels to four cycles: Heat, eold, 
 rain spray and ultra-violet light. The entire apparatus is 
 made of 16 gauge heavily galvanized iron. It consists of a — 
 revolving drum five feet in diameter with a fourteen-inch face — 
 upon which the test panels are fastened. The drum accommo- ~ 
 dates 31 panels 6 inches by 12 inches and 1 inch thick. Such | 
 panels are of greater size than used in most testing cabinets — 
 
 Pay ee “ 
 
Accelerated Testing Cabinets Sid 
 
 previously constructed. They afford sufficient surface for 
 brushing or spraying a coating under test. The drum re- 
 volves on bearings fastened to the sides of a tank 3 feet deep, 
 arranged for holding ice water or refrigerating pipes. The 
 drum is operated by a Ye H. P. 110 volt A. C. motor which, 
 revolving at a speed of 1725 r. p. m., operates a pulley with 
 a 64% to 1 reduction. The pulley is fastened to two worm 
 gear units which give a further reduction of 8281 to 1, thus 
 reducing the speed of the drum to 1 revolution per half hour 
 (total reduction 51,750 to 1). 
 
 The panels first pass in front of a rain spray furnished by a 
 Schutte-Koerting spray nozzle No. 622-B, then pass below an 
 ultra-violet ight furnished by a mercury quartz tube of the 
 Cooper-Hewitt type No. BW-040. The panels then pass in 
 front of a battery of twelve 100 watt electric bulbs which give 
 the desired heating effect and some efficiency from the stand- 
 point of light source. They then pass into ice water or over a 
 series of refrigerating pipes to secure the desired cooling 
 effect. The last two cycles may duplicate the strains developed 
 on automobile finishes when a motor ear is driven from a 
 heated garage (70° F.) into the open air on a cold morning 
 (20° F. or lower). The rain spray and the ultra-violet light 
 might be considered equivalent to alternate exposure to thun- 
 der storms and strong sunlight in the summer months. The 
 ozone produced by the Mereury Are Light may also greatly 
 stimulate the breakdown of finishes. 
 
 This apparatus has been in almost continuous use for a 
 period of two years and has given much information regard- 
 ing the durability of lacquer coatings. Exposure for 200 hours 
 often gives the same type of chalking and surface decay that 
 is observed upon roof tests conducted in the summer months 
 for a period of from 60 to 90 days. The results, however, upon 
 this type of accelerated testing cabinet do not approximate 
 those obtained upon roof exposure tests with paints and var- 
 nishes of the oil type, as will be shown on pages 312 and 313. 
 
 One of the defects of this type cabinet is the fact that the 
 panels are only submitted to the effects of ight during part 
 of the revolution of the wheel. If the light had been placed 
 in the middle of the wheel so that the panels would at all 
 times have received exposure to the light, much more rapid 
 results would doubtless have been obtained. A cabinet based 
 
Accelerated Testing Cabinets 
 
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314 
 
 Accelerated Testing Cabinets 
 
 FIGURE 111 
 
 Photo Micrograph X 50 of Pigmented Nitrate Dope 
 on Accelerated Wheel 219 hours. 
 
 FIGURE 112 
 
 Photo Micrograph X 50 of Clear Lacquer (12-ounce 
 solution of Cellulose Nitrate with Resin) on 
 Roof 744 weeks. 
 
 ~ canal 
 
Accelerated Testing Cabinets 315 
 
 FIGurRE 113 
 
 Photo Micrograph X 50 of Pigmented Dope on 
 Roof 7144 weeks. 
 
 FIGuRE 114 
 
 Photo Micrograph X 50 of Pigmented Dope in 
 Ammonium Carbonate Cabinet 212 hours, 
 
316 Accelerated Testing Cabinets 
 
 FIGURE 115 
 
 Photo Micrograph X 50 of Pigmented Auto Lacquer 
 on Roof 7% weeks. Surface roughness is due to 
 chalking. No checking or other film defects. 
 
 FIGURE 116 
 
 Photo Micrograph X 50 of Outside White Paint on 
 
 Accelerated Test Wheel 290 hours. Film scratched 
 
 with Sapphire Needle Tester to show effect of ultra- 
 violet light ‘on making film chalky. 
 
Accelerated Testing Cabinets 317 
 
 upon such a design is now under construction. A description 
 of it will probably appear in a scientific circular to be issued in 
 November, 1927. 
 
 Walker-Hickson Cabinet. A type of accelerated cabinet 
 devised by P. H. Walker and E. F. Hickson of the Bureau of 
 Standards has been in service at the Bureau for several 
 months, with apparently satisfactory results. Much smaller 
 panels are used in this apparatus than with the other types 
 described in this chapter. There are shown herewith two 
 views of the apparatus as described by Walker in his paper 
 entitled ‘‘Some Methods of Testing Paint and Varnish Ma- 
 terials,’’ presented before the International Congress of Test- 
 ing Materials, at Amsterdam, Holland, September, 1927. 
 
 FIGURE 117 
 
 Ozone apparatus used by Walker and Hickson. 
 
318 Accelerated Testing Cabinets 
 
 Figure 118 
 
 Walker-Hickson tank with ultraviolet light equipment. 
 
 Figure 118 shows carbon are equipment with lamp raised 
 out of cylinder. When in use it is lowered so that the are 
 is at the level of the center of the 7.5x15 em. test. panels 
 
Accelerated Testing Cabinets 319 
 
 held in the slots on the inside of the cylinder, which is 76 em. 
 in diameter, 38 cm. high, open at both ends and suspended 
 with its lower edge 5 em. above the edges of a pan containing 
 water. <A circular perforated tube serves to apply oceasion- 
 ally a light shower of water to the panels while exposed to 
 hght. 
 
 Figure 117 shows cabinet for exposing panels to ozonized 
 air. Air is forced by means of the small motor-driven fan, 
 shown in the lower left corner, through a silica gel dehy- 
 drator, then through a calcium chloride bottle, which serves 
 to indicate that the silica gel is working efficiently, to the 
 ozonizing aparatus and thence to the glass chamber on the 
 right for holding the panels. Some water is placed on the 
 bottom of this glass chamber to moisten the ozonized air. 
 This equipment delivers about 660 liters per hour of air con- 
 taining 0.56 liter of ozone, equivalent to about 0.08 per cent 
 of ozone by volume. 
 
 For the vigorous spraying with water the panels are trans- 
 ferred to another cabinet, of which no picture is available or 
 necessary. 
 
 In the course of a week the panels are 112 hours in the light 
 eabinet, 21 hours in the ozonized air cabinet and 32 hours in 
 the rain cabinet. This leaves 3 hours for inspection. 
 
 Hopkins-Murphy Cabinet.—An accelerated test apparatus 
 used by F. W. Hopkins of the Murphy Varnish Co. is de- 
 seribed below by Mr. Hopkins. 
 
 Our apparatus consists of three tanks reproducing light, 
 water and refrigeration. The light and water tanks are of 
 wood, 31 inches high, 42 inches in diameter and are lined with 
 galvanized iron. A 6-inch Cooper-Hewitt U V Arc Lamp is 
 centered in the light tank as a source of ultra-violet radiation. 
 The tank is also equipped with an automatic electric heat 
 control, an atomizer and a circulating fan on the side which 
 keeps the lamp cool. The air circulating system has a water 
 jacket so that in summer the same temperature can be main- 
 tained as in winter. The average temperature in the light 
 tank is 140 to 150° Fahrenheit, and the relative humidity 75 
 to 80 per cent. The water tank is equipped with an ordinary 
 revolving lawn sprinkler which has three arms. 
 
 The refrigeration unit consists of a brine tank and an inner 
 compartment which is 24 inches in length, width and depth. 
 These tanks are insulated with six inches of cork board and a 
 ¥z inch siding, also a double cover. A small Frididaire ice 
 cream compressor 1s used to compress the sulphur dioxide 
 
320 Accelerated Testing Cabinets 
 
 which circulates through a coil in the brine tank. The mini- 
 mum temperature obtained is 20° below zero. 
 
 The present cycle consists of 56.1 per cent light, 26.7 per 
 cent water and 17.2 per cent refrigeration. 
 
 Because of the high degree of distensibility of varnish, a 
 change of panels from water to light, and water to refrigera- 
 tion are more effective than the same changes when lacquer 
 is being tested. In the case of lacquer, a light to refrigera- 
 tion change effects a quicker breakdown. By the use of tem- 
 peratures below 0 Fahrenheit, it is not necessary to use a fan 
 to cool the panels in the refrigerator, as the sudden change 
 from over 100° Fahrenheit to 0 Fahrenheit, a period of two 
 hours, is sufficient time for the refrigeration exposure, the 
 eycle having one change from light to refrigeration every day. 
 
 A microscopical examination with a binocular microscope, 
 using a magnification of 30X, is made of the panels once a 
 week. In interpreting results, change of color, loss of lustre, 
 chalking, peeling and cracking are considered. The change of 
 color is determined whether due to the breaking down of the 
 nitro cellulose, or a fading or darkening of the pigment used. 
 The loss of lustre begins with the first signs of chalking, which 
 takes approximately 150 hours’ exposure in the eyele. The 
 amount of chalking is determined by rubbing the panel with 
 a small piece of felt once a week, excess chalking being due 
 to either an excess of pigment or lack of a binder. Under- 
 eoats which do not properly adhere to the surface applied 
 cause peeling. Cracks are caused by undry underecoats or 
 an improper balance between the primer, surfacer and finish- 
 ing coat. Crowfeet cracks are found only in the finishing 
 coat. When a pigmented lacquer is tested over bare metal, 
 a pinhead crack is formed, which in time causes the finish 
 to peel from the metal, leaving small pits in the surface. A 
 very interesting crack, hard to describe, is caused by an excess 
 of plasticizer in proportion to the amount of nitro cellulose 
 used. 
 
 By increasing the oxygen content of the air in the light 
 tank, the Research Division of the New Jersey Zine Company 
 has found that they have increased the ratio of outside ex- 
 _ posures in comparison to accelerated exposures from one to 
 seven to one to fifteen. In comparison with roof exposures, 
 we think that with the present cycle, a ratio of one to eight 
 is established. With the data, which we have obtained from 
 the New Jersey Zine Company, in mind, we have found that 
 by the introduction of the ozone into the light tank by means 
 of connecting the ozinator to the air circulating system, it is 
 possible to produce the same cracking in approximately one- 
 
Accelerated Testing Cabinets 321 
 
 third of the time that it takes without the use of ozone. The 
 amount of ozone used is approximated at 0.25 grams per 
 hour. 
 
 Figure 119 
 
 Weather-O-Meter for accelerated tests on protective coatings. 
 
322 Accelerated Testing Cabinets 
 
 Atlas Weatherometer Cabinet.—An apparatus built by the 
 Atlas Electric Devices Co. of Chicago has been in successful 
 use in several paint laboratories. It is described below: 
 
 The Weather-O-Meter is a new scientific instrument that 
 shortens the weathering period of on-the-roof tests from 
 months and years to days and weeks, and gives the plant 
 equipped with a Weather-Ometer years of advantage over 
 plants that are not equipped with an accelerated weathering 
 machine. In this instrument the elements of sunlight, rain, 
 and wind can be controlled to suit the requirements of the 
 test that. is being run. This instrument predetermines the. 
 weather resisting qualities of paint, varnish, lacquer, roofing 
 material, rust-proof iron, alloy, and any material subject to 
 outdoor weather conditions. 
 
 In this instrument the samples to be tested rotate continu- 
 ously, completing one cycle in twelve or twenty-four hours, 
 depending upon the gearing arrangement, whether it is geared 
 for two twelve-hour periods and one twenty four-hour period. 
 The eighteen samples, which are usually 3 x 8 inches, are sub- 
 jected to the elements of sun, rain, and wind in the following 
 relationship : 
 
 (1) Sunhght falls on the samples for sixteen consecutive 
 hours. 
 
 (2) Samples are now cooled to near 5 degrees below room 
 temperature for a period of four hours. | 3 
 
 (3) From the period of cooling the samples are subjected 
 to four hours of rain, approximate temperature is 5° F.. below 
 room temperature. 
 
 (4) They are now turned back into the period of sunlight, 
 which has its greatest destructive power here just as in the 
 out-of-doors after a rain. All these periods may be varied 
 according to the needs of the individual plants. 
 
 (5) A temperature range can be adjusted through the ther- 
 mostat so that the maximum and minimum ranges are variable. 
 However, the usual range would be from 100° F. to 150° F., 
 with control elements of 5 to 15°. However, without the 
 blower, the temperature easily rises to 190°, which greatly 
 accelerates the weathering test. 
 
 Special features, such as thermostatically controlled shut- 
 ter, which maintains a constant temperature, four thermo- 
 meters, humidifier, blower, and other special apparatus, are 
 included. 
 
 The violet flaming carbon arc is the lamp used in this instru- 
 ment, due to the fact that its spectrum so closely resembles 
 that of sunlight and is the nearest possible reproduction of 
 
Accelerated Testing Cabinets ead 
 
 sunlight in the out-of-doors. The big advantage of the carbon 
 are lamp is that it is not easily breakable nor does it change 
 in its constancy of ultraviolet rays as the lamp is used. 
 
 The entire machine is made out of Monel non-rusting alloy, 
 copper, brass, and machined steel. The meta] parts in contact 
 with the water are all of rust-proof material. The instrument 
 is finished in lacquer on those parts that do not already have 
 a natural finish. : 
 
 The instrument operates on a 220 volt, direct or alternating 
 current circuit, the current consumed is 24 amperes. When 
 operated on 110 volt A. C. circuit, a transformer is added to 
 the cireuit to bring the voltage up to 220 volts. The instrn- 
 ment does not operate on 110 volts direct current or an alter- 
 nating current under 40 cycles or over 133. 
 
 Croll-Jenkins Cabinet.—The accelerated exposure equip- 
 ment used at the Milwaukee Laboratories of the Pittsburgh 
 Plate Glass Co. (Paint Division) comprises a refrigeration 
 room and a light and moisture tank. The refrigeration room 
 proper is 9 ft. by 12 ft. by 8 ft. high. It is insulated by a two- 
 inch layer of cork, and provided with a double window and a 
 refrigerator door. Within this room is a tank 5 feet high 
 and 6 feet in diameter, supplied by an individual air duct from 
 the refrigeration equipment. The hight and water tank jis 
 also 5 feet high by 6 feet in diameter. 
 
 Both tanks are provided with hexagonal racks rotated by 
 motors operating through speed reducers and bevel-gears and 
 so arranged as to rotate once every ten seconds. 
 
 The panels are exposed in panel holders. They hold three 
 6° by 12” panels, bolted with brass bolts, one above another 
 and spaced out from the holders by strips of 4% inch square 
 beading at the top and bottom of each panel. This spacing 
 provides drainage and air circulation behind the panels. The 
 holders are hung vertically from the top bar of the hexago- 
 nal rack by means of two small hooks on the back of the 
 holder. The tanks are fitted with covers and the light tank 
 is equipped with three Spray nozzles set one foot apart on a 
 vertical pipe and adjusted to Spray evenly on the three rows 
 of 6° by 12” panels from a distance of two feet. 
 
 A 30° quartz mercury arc is suspended in the center of the 
 tank through a 6” hole in the top. It is so hung that its center 
 is on a level with the center of the middle panel. 
 
 It may be assumed that over a relatively large number of 
 
324 Accelerated Testing Cabinets 
 
 changes, from the water-light tank to the refrigerator tank 
 and back, the law of chance will cause any one panel holder 
 to oceupy each of the five possible positions an equal number 
 of times. Consequently, the variation of intensity between 
 the middle position for the panel holders and the outside posi- 
 tions will be offset. 
 
 The top and bottom panels, however, will always get less 
 light than the corresponding center panel, about 90% for the 
 top and bottom as compared to 100% for the center, and this 
 can only be eliminated by changing the panels around. 
 
 Most of the work with this equipment during the last nine 
 months has been with lacquer base materials. Here it has 
 been found very useful for comparative tests between rela- 
 tively similar materials. Attempts to correlate the results 
 of these tests with outside exposure panels, however, have 
 been less fruitful. The reasons for this are fairly obvious. 
 
 In the first place, the normal manner of failure of such 
 finishes as automobile enamels and clear lacquers is by chalk- 
 ing or disintegration by light. However, the variation in the 
 amount of sunlight and its content of the active short wave 
 lengths, or ultraviolet light, is very marked between summer 
 and winter. As a result, lacquers will be much longer liyed 
 during the winter than during the summer months on exterior 
 exposure. 
 
 In products which fail by cracking or checking, the type 
 of failure can usually be approximated, but the time ratio 
 of accelerated to normal exposure varies somewhat. 
 
 McMullin Accelerated Cabinet.—E. W. MeMullin, Chemist 
 of the Simmons Company, Kenosha, Wis., at a recent meet- 
 ing of Committee D-1 of the American Society for Testing 
 Materials, stated that he had devised an apparatus for test- 
 ing finishes upon metal beds and similar material, by expos- 
 ing the coated panels in a cabinet containing vapors of a 
 dilute aqueous solution of ammonium carbonate. In a sub- 
 sequent communication to the writer, he stated that the 
 cabinet was 30” by 20” by 14”, made of a wooden frame with 
 back, top and bottom of tongue-and-groove boards, and with 
 glass doors on front and back. He used a graniteware dish 
 having a capacity of about 2000 ce. kept supplied with a one- 
 half of one per cent (0.5%) solution of ammonium carbonate. 
 Wooden racks upon which to expose panels were placed above 
 
Accelerated Testing Cabinets 325 
  _____._.._.____.._._— 
 the pan. Air vents were supplied at the bottom and top of 
 the cabinet, and a gas burner for heating the solution. Using 
 a wet and dry bulb thermometer, and by regulating the flame, 
 the temperature was kept about 95° F. and the humidity 
 about 90%. He stated that while he has not sufficient data 
 
 === 
 ———— = 
 
 9 GOA 
 
 Figure 120 
 
 Accelerated Test Cabinet for Metal Finishes. 
 
 to compare the length of time a finish stands up in this cabinet 
 to its outdoor or even indoor exposure, he can obtain some 
 idea of the practical life of a finish and get a very close com- 
 
326 Accelerated Testing Cabinets 
 
 parison of the value of any two finishes when exposed simul- 
 taneously in the cabinet. 
 
 Based on the above, the present writer has designed a some- 
 what similar cabinet as shown in the attached Figs 12a 
 It is made of heavily coated galvanized iron of 18 gauge, two 
 and a half feet square, three feet high, and provided with a 
 metal cover. An electrical heating device is used instead of 
 a gas flame. A somewhat different arrangement of the pan- 
 els is made, suspending them rather than placing them upon 
 racks. The cabinet has a cover supplied with air vents. Tests 
 made with this cabinet apparently do not check with the results 
 obtained with cabinets in which there is exposure of the panels 
 to cycles of ultraviolet light and water spray or with exterior 
 exposure tests. Nevertheless, the results may be compara- 
 tive and thus afford some information when studying the 
 possibilities of a number of different finishes for one specific 
 purpose. 
 
 Palmerton Cabinet.—More work has probably been done 
 by Nelson and Breyer of the New J ersey Zine Co. laboratories 
 
 Atomizing 
 7 Sproy nozzles. 
 
 FIGURE 121 
 
 Type of apparatus that has been successfully used in accelerated 
 weathering experiments. (Nelson. ) 
 
Accelerated Testing Cabinets aya 
 
 than by any other investigators in this country on the subject 
 of accelerated tests involving ultraviolet light. The work of 
 these investigators covers a period of several years. The 
 importance of their work is so great that there has been pre- 
 sented below an article on the subject, describing their appa- 
 ratus and the developments to date. This article, which 
 has been prepared by H. A. Nelson and F. C. Schmutz, is 
 presented in full, together with a number of illustrations. 
 
 March Apr Ma JUure July A 
 
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 FIGURE 122 
 
 Comparison of gloss depreciation curves on typical single pig- 
 ment paints under outdoor and accelerated weathering condi- 
 tions. (Nelson.) 
 
328 Accelerated Testing Cabinets 
 
 Valuable beginnings of experimental work with accelerated 
 tests were made by Gardner’ and by Muckenfuss?. The lat- 
 ter developed an exposure scheme which was designed to take 
 advantage of the changes in permeability of paint and var- 
 nish films, applied on fine mesh screen or hardened paper, to 
 moisture as a measure of deterioration under artificial expos- 
 ure conditions. The exposure involved lght (mereury are 
 and tungsten), moisture (revolving spray) and cool weather 
 (outdoor night exposures). 
 
 Other, more recent, investigations*® were directed toward a 
 possible simplification of the application of the idea of accel- 
 erated weathering. The ideal would, of course, be artificial 
 accelerated reproduction on painted wood and metal surfaces 
 of the normal failures that are observed under outdoor expo- 
 sure conditions. The first laboratory evidence that this might 
 be possible was the fact that an ordinary 100% Basie Car- 
 bonate White Lead—linseed oil paint film could be made to 
 chalk heavily by exposure for about 13 hours under an ordi- 
 nary 220-volt mereury are lamp. The particular importance 
 of the radiations from the ultraviolet portion of the spectrum 
 (below A = 3800 A. U.) was then demonstrated by the fact that 
 only some loss of gloss could be obtained by exposing similar 
 
 Section 8 
 Latches 
 4 
 
 pa 
 
 Revolving Spray 
 
 Fig. 1 
 Section A 
 
 A-Exposure Tank J- Humidifier 
 B-Mercury Arc K- Steam Jacket 
 C- Oxygen Inlets L-Water Drain 
 O- Rubber Seal M-Air Pump max. cap. 20cu.ft per min. 
 E- Psychrometer (Wet & Dry Bulb)- N-Silica gel Dehydrator 
 F~ Air Circulating Fan O-Compressed Air 
 G- Paint Panels (Cap. 50- 9"«12’) P-Heater 
 H- Peep Hole Q-Air Cooler 
 I- Gas Inlet R-Water Inlet 
 FIGURE 123 
 
 Plan of accelerated testing equipment at New Jersey Zine Compuny’s Research 
 Laboratory at Palmerton, Pa. 
 
Accelerated Testing Cabinets 329 
 
 films for about 300 hours at a short distance from an ordinary 
 glass blue-printing lamp (mercury arc). 
 
 For further experiments, a special vertical quartz burner, 
 30° long, was developed so that panels in large numbers and 
 of appreciable surface area (6°x12") might be used. Only 
 light and moisture were extensively used in the first experi- 
 ments and the following results were obtained with paints 
 and varnishes on wood and metal panels: 
 
 (1) Loss of gloss and subsequent chalking were easily re- 
 produced by exposure to ultra-violet radiations in and below 
 the region 4 = 3600 A. U. 
 
 (2) Loss of gloss and chalking were hastened by periodic 
 saturation of the paint film, or by maintaining a saturated 
 atmosphere in the apparatus during the period of ultraviolet 
 exposure. | 
 
 (5) Paints made with pigments which chalk readily upon 
 normal outdoor exposure were the ones which chalked readily 
 under the ultraviolet light. Those pigments which normally 
 retard loss of gloss and chalking under outdoor exposure 
 conditions were found to act similarly under the accelerated 
 conditions. 
 
 (4) Comparisons made with results from outdoor exposures 
 showed a ratio of approximately 1 to 30 for loss of gloss and 
 initial chalking. For this the accelerated exposure scheme 
 was 24 hours light-cool-24 hours water spray. This approxi- 
 mate ratio was then found to exist for’a number of paint 
 combinations representing both chalking and non-chalking 
 pigments. (It should be noted, however, that low tempera- 
 ture exposures were not generally included in these experi- 
 ments, and that the conditions of the exposure were what are 
 ie to be very severe for producing a chalking fail- 
 ure. 
 
 (5) Chalking, onee started by exposure to light, was ac- 
 eelerated by exposure to low (freezing) temperatures, espe- 
 cially when the film had been previously saturated with mois- 
 ture. 
 
 (6) Cracking was then reproduced to a limited extent on 
 certain paints and varnishes, but only with marked success 
 when some variations of temperature were introduced (out- 
 door exposures in winter were used). 
 
 The above results went far toward proving the practica- 
 bility of the method, and the experiments were continued after 
 the installation of a refrigerating equipment which made low 
 temperatures available down to about —16° C. 
 
 Effect of Variations in Exposure Cycle.—The possible ef- 
 
330 Accelerated Testing Cabinets 
 I 
 
 fective variables which could then be introduced with the 
 equipment at hand were: 
 
 (1) Light and heat (50° C. to 60° C.) at comparatively low 
 humidities. (Air taken in at outdoor temperatures.) 
 
 (2) Light and heat with saturated atmospheres. 
 
 (3) Water spray (washing action of rains). 
 
 (4) Low temperatures (down to —16° C.). 
 
 FIGURE 124 
 
 Accelerated Weathering Equipment—Unit for exposure to light and water 
 under controlled conditions (see Figure 123). Capacity 50 panels, 6” x 12”. 
 
 Early in the work it was evident that the ratios between 
 outdoor and accelerated weathering would vary with the 
 nature of the exposure cycle used. That great variations in 
 the rates of outdoor deterioration are introduced by climatic 
 differences is also common knowledge. Obviously, then, the 
 next important step was to begin a study of the relative deteri- 
 orating effectiveness of each weathering factor (alone and in 
 combinations) as it might be used in an accelerated weath- 
 ering cycle. 
 
 A comprehensive series of tests with this object in view was 
 made on a group of representative varnishes, of which the 
 detailed results can be found in the literature.t It is im- 
 portant to note that very great variations are observed in the 
 degree and type of deterioration, depending what factors are 
 
 Re 4 ca foe 
 
Accelerated Testing Cabinets aieM! 
 NN eS SSS Sess} 
 included in the exposure cycle and the frequency of change 
 from one kind of exposure to another. Briefly, the following 
 conclusions were arrived at as to the apparent relative deteri- 
 orating effectiveness of the exposure factors. 
 
 (1) Most effective (especially in deadening or reducing 
 the distensibility of the film) was a water exposure followed 
 by light. | 
 
 (2) Second and almost as effective was the water exposure 
 followed by refrigeration. This apparently not only helped 
 take the elastic life out of the film, but also acted as a factor 
 
 in revealing the deterioration brought about under hght and 
 water, ete. 
 
 OUTDOOR RESULTS 
 Paint No. 1 Paint No. 2 Paint No. 3 
 
 Paint No. 1 Paint No, 2 Paint No. 3 
 ACCELERATED RESULTS. 
 FIGURE 125 
 
 Photomicrographs of typical paints, showing failures produced by accelerated 
 and outdoors exposures. 
 
 (3) Next in effectiveness was light (warm and dry) fol- 
 lowed by refrigeration. This combination apparently served 
 largely as a factor which brought out, or revealed weaknesses 
 in the film which might be inherent with the original material 
 or introduced by other exposures. 
 
 (4) Considerably lower in effectiveness was the action of 
 light alone. (This refers to the ‘‘deadening”’ action of light 
 
332 Accelerated Testing Cabinets 
 
 after the excess absorbed water has passed off and the film 
 ‘is fairly dry. The lower the moisture in the film the slower 
 is the action of light.) 
 
 (5) Next was water alone which, in itself, appeared to have 
 a deteriorating effect. 
 
 (6) Continued refrigeration, after the film had attained 
 equilibrium at the low temperature, had no appreciable de- 
 teriorating effect. 
 
 Exposure cycles involving moisture and light were most 
 effective when changes were made frequently. Thus the 
 film was practically always in a saturated state and the light 
 did most damage. Light-refrigeration cycles brought about 
 eracking most quickly with frequent changes, but the final 
 deterioration was greatest under longer periods of exposures 
 when the light deterioration became proportionately greater. 
 Water-refrigeration was most effective with moderately fre- 
 quent changes. 
 
 More Recent Development of Apparatus—Oaygen and 
 Ozone Atmospheres.—Up to this stage of the investigations, 
 difficulty had been encountered in reproducing common check- 
 ing types of failures such as commonly appear on ordinary 
 paint surfaces. Consideration of the possible causes of this 
 type of failure lead to the conclusion that it is induced to a 
 large extent through excessive hardening or contraction of 
 the paint film at the surface. To test this, an apparatus was 
 so designed that the oxygen content of the atmosphere could 
 be increased at will. A concentration of 30% by volume of 
 oxygen was used. The results were gratifying, checking types 
 of failures being reproduced. Another result was that the 
 general deterioration rate for paint films was practically 
 doubled so that the whole testing process was speeded up. 
 
 It was then suggested that ozone be tried instead of oxygen. 
 However, its activity proved so great and the mechanical dif- 
 ficulties in providing exact control of the quantities of ozone 
 introduced were such that the results in these experiments 
 were not encouraging. One effect noted, even when very 
 small proportions of ozone were used, was the extreme ten- 
 dency of lead bearing paints to darken due to the formation 
 of a reddish brown surface film of lead oxides. 
 
 Conditioning of the Atmosphere in the Light Exposure 
 Chamber.—The desirabilitv of having periodic exposures 
 under dry atmospheric conditions is evident when we consider 
 the effect of absorbed moisture on the physical pronerties of 
 oleo-resinous films, in particular, and on nitrocellulose films 
 where appreciable amounts of more or less hygroscopic gums, 
 
Accelerated Testing Cabinets S33 
 
 etc., have been incorporated. For testing work of this kind, 
 there is no obvious reason why we should be particularly in- 
 terested in reproducing any conditions except the two ex- 
 tremes—saturated and dry. A great forward step in main- 
 taining these conditions in an easy and practical way was 
 accomplished by substituting a simple silica gel dehydrator 
 (‘““N”’ Figure 123) for air conditioning by refrigeration. This 
 necessitated apparatus so designed’ that the air could be re- 
 circulated through the dehydrator. In order to relieve the 
 silica gel dehydrator of excessive load, a condensing coil 
 (“‘Q”’ Figure 123) is provided in the cireuit, which removes 
 part of the moisture. In this manner the conditions in the 
 exposure chamber can be changed from saturated to approxi- 
 
 Accelerated ; Outdoor 
 FIGURE 126 
 
 Comparative results on two white outside house paints, one of which tends 
 to crack and the other to chalk away uniformly in service. 
 
: ‘ 
 ay ens . 
 
 334 Accelerated Testing Cabinets 
 
 Accelerated 
 
 (with auxiliary exposure to SO,, CO, and air mixture) 
 
 en ee 
 
 ee aes 
 
 Outdoor (45° angle, facing south) 
 
 FIGURE 127 
 
 Comparing results of industrial accelerated and outdoor exposures r 
 of paint on steel sash bars. 4 
 & 
 
 mately 5% relative humidity in times ranging from 10 to 30 
 minutes, depending on the size of the unit. 
 
 The exposure unit shown in Figures 123 and 124 represents 
 equipment designed to enable the operator to reproduce any 
 of the following conditions at will: 
 
 (1) Light (Mercury or Carbon Are) 
 
 a. At controlled temperatures. 
 b. With 100% relative humidity. 
 
Accelerated Testing Cabinets 335 
 
 e. With less than 5% relative humidity. 
 d. In atmospheres charged with active gases, as, for 
 example, oxygen. 
 
 (2) Water Spray (by removing the Light and Substituting 
 the Revolving Spray). 
 
 This unit, constructed of galvanized iron and, using ordi- 
 nary pipe fittings throughout, complete with pump, dehy- 
 drators, spray equipment, 20” quartz mercury are, control 
 equipment, etc., cost between $550 and $600. Obviously, the 
 use of Monel metal and brass for many parts would be good 
 economy, although it might increase the cost by $50 to $100. 
 
 Aualiary Exposures to Corrosive Gases (SO2 and COz)— 
 Such an auxiliary test® has been inserted with considerable 
 success in the regular weathering cycle for testing metal pre- 
 servative paints, in particular. This part of the test is con- 
 ducted in a,dark chamber with a high humidity and a tempera- 
 ture of about 100° F. (These gases seem to have very little 
 effect on a paint film while it is being exposed to light.) The 
 gases have been used in proportions such as 1000 parts of air’ 
 to 12 parts carbon dioxide and 1 part sulfur dioxide. Higher 
 gas concentrations had better be avoided in order to keep the 
 formation of water soluble reaction products from becoming 
 too much of a factor in the deterioration process. 
 
 Comparison with Outdoor ,Exposure Results.—As pre- 
 viously stated, in the early experiments a certain approximate 
 relation was established between outdoor and accelerated 
 weathering results, especially in so far as chalking types of 
 failures were concerned, when moisture and hght were the 
 major factors involved. It was also subsequently pointed 
 out that this ratio did not hold when the exposure cycle was - 
 modified to any appreciable extent, as, for example, by adding 
 low temperature exposures. 
 
 Figure 122 illustrates how deterioration of outdoor expos- 
 ures, as measured by loss of gloss and chalking, compares 
 with an arbitrarily selected accelerated exposure cycle in 
 which light, moisture and refrigeration have the same aver- 
 age ratio as observed for sunshine, rain and low tempera- 
 tures at Palmerton, Pa., for a period of one year. The curves 
 are plotted on a 1.7 ratio (outdoor exposure March to August, 
 inclusive — 1924). But experiments also showed that this 
 1.7 ratio may not hold if the outdoor exposure is begun at 
 another season, nor have we any reason to expect that it 
 would. Hssentially, then, all that these curves tell is that 
 the reactions of the films to the weathering agents as they 
 
336 Accelerated Testing Cabinets 
 
 were used in this experiment are very similar even with 
 paints made with pigments that differ so radically in their 
 known properties, but this in itself is very significant. 
 
 Until oxygen was added to the atmosphere in the light 
 exposure chamber and effective means were provided for in- 
 troducing humidity changes as mentioned above, checking — 
 and cracking types of failures were not reproduced in a very 
 representative manner. This was the case with paints, es- 
 pecially. Figure 125 shows photomicrographs of three repre- 
 sentative exterior paints on steel which illustrate the results 
 obtained when the full combination of weathering agents was 
 used, as compared with exterior exposures of the same 
 paints. The exposure ratio when the photographs were taken 
 was 1:19. Other tests have indicated a ratio of from 1:14 
 to 1:16 for the beginning of chalking or checking. Con- 
 sidering the large number of variables involved, these results 
 have shown a fair degree of concordance. , 
 
 The additional use of auxiliary exposures to dilute SOs, 
 CO. and air mixtures (see above) in testing the corrosion 
 resistance of industrial paints on iron and steel does not ma- 
 terially upset this ratio, as demonstrated by the photographs 
 shown in Figure 127 of a series painted steel sash bars. The 
 ratio of exposure of the samples as shown was approximately 
 1:12. It is important to note the excellent agreement of the 
 relative results attained by the two tests on individual sam- 
 ples. | 
 
 The problem of establishing an exact ratio is complicated 
 by the variations in atmospheric conditions. It would be 
 surprising, indeed, if the ratios found for Eastern Pennsyl- 
 vania, for example, would agree with the same exposure cycle 
 when compared with exposures in the South or Middle West; 
 that is, the accelerated cycle will have to be modified to suit 
 the exposure conditions that are to be simulated. Possibly 
 climates can be classified according to characteristic types 
 and a series of standard cycles designed to meet the require 
 ments of any particular class of climate. 
 
 Light Sources.—Practically all of the work so far reported 
 on accelerated weathering of paint and varnish products has 
 been done with the mercury are. Convenience in handling 
 and the fact that the long tubes permit uniform exposure of 
 large test surface areas have undoubtedly encouraged their 
 use. But essentially, there is no reason why other sources 
 of ultraviolet energy should not be used if they can be made 
 mechanically adaptable to the other requirements of the test- 
 ing scheme. Treated carbon electrodes” that closely simu- 
 late sunlight are now commercially available. (Such as the 
 
Accelerated Testing Cabinets 337 
 
 National Carbon Company’s Therapeutic ‘‘A’’ electrodes.) 
 However, such treated carbon ares are more difficult to handle 
 within an enclosing globe because of the rapidity with which 
 the products of combustion from the electrodes cloud the sur- 
 face of the globe. Experiments are now under way with 
 apparatus designed to overcome this difficulty, but no results 
 can be reported. 
 
 The mercury are does have a serious weakness in the fact 
 that the ultraviolet transmission of the quartz tube drops as 
 the burner is used. Flynn’ reports an interesting way to 
 compensate for this. He found it desirable to mellow the 
 burners for about 500 hours. This was accomplished with a 
 220-volt burner by starting it at 160 volts drop in the are 
 proper and increasing the voltage drop at the rate of 2 volts 
 for every 100 hours of operation for the first 500 hours. After 
 this, he claims, no change is necessary during the remaining 
 several thousand hours of the life of the burner for dye test- 
 ing. 
 
 Whether or not the radiations in the ultraviolet have a 
 selective action on linseed oil and other organic binders, or 
 if the deteriorating effect merely increases directly as the 
 wave lengths of the ultraviolet radiations are decreased, is a 
 question that has caused much concern among those interested 
 in this problem. The experience of the dye industry, as 
 shown by Harrison* and Flynn® is that for certain dyes, which 
 are faded by reducing reactions, the radiations below about 
 4 = 2900 A. U. must be filtered out to obtain results compara- 
 ble with sunlight exposures. This is especially true on cotton 
 which, Flynn concludes, becomes very actively reducing under 
 the action of radiations much below 4 = 2900 A. U. Aceord- 
 ingly, for such dyes, the are was tempered by interposing thin 
 sheets of crown glass. It is possible that such side-reactions 
 might also take place in paint and varnish films, but the indi- 
 cations are that under the experimental conditions these are 
 not an important factor, if they take place at all. For ex- 
 ample, preliminary experiments (28 inches from a 220-volt 
 D. C. 30” tube, operated at 9 amperes) on paints with a series 
 of special glass filters, which cut out the ultraviolet step by 
 step, show that all of the gloss reduction curves under the dif- 
 ferent filters are quite similar in form, the main difference 
 being in the rate at which the gloss falls off and surface chalk- 
 ing takes place. That is, filtering out the shorter wave lengths 
 of ultraviolet light merely lowers the rate at which the deteri- 
 orating reactions progress. 
 
 Recent spectrograms, reported by Stutz,’° of tungsten spec- 
 tra (which are practically continuous) taken through films 
 
338 Accelerated Testing Cabinets 
 
 of linseed oil throw further light on this subject. These 
 spectra show no absorption bands within the range covered 
 by the mercury are, which would indicate that no selective 
 action on linseed oil, at least, is to be expected. However, in 
 this same work, it is shown that the short wave lengths are 
 largely absorbed at the surface where their action would be 
 concentrated. This would account for the excessive chalk- 
 ing observed when samples are exposed under an are that has 
 a very large percentage of energy in the ultraviolet, as the 
 6° clear quartz high pressure mercury are. 
 
 It should be noted that the results shown in Figure 122 are 
 from panels exposed without interposing any light filter. 
 Properly speaking, however, this light source (30° are) is 
 tempered when we consider the distance from the are (28 
 inches) and the fact that the quartz used in these burners is 
 not of the highly transparent grade. (The so-called Thermal 
 Syndicate Stock quartz is used.) The results in this labora’ 
 tory in favor of using burners of this type, which can now be 
 obtained in 30", 20” and 10” lengths, have been quite convincing 
 and they are recommended for use in accelerated weathering 
 tests where the mercury are is to be used. 
 
 Hxposure Cycles.—The development of suitable exposure 
 
 eycles is in itself a subject that cannot be adequately dis- 
 cussed here and the reader is referred to the literature on the 
 subject.’,° A great deal of work remains to be done on this 
 subject. However, a typical cycle, that has met with a rea- 
 sonable degree of success when used i in testing paints intended 
 to meet industr ial exposure conditions, as encountered about 
 
 the industrial plants at Palmerton, Pa, i is as follows: 
 
 TENTATIVE CYCLE FOR INDUSTRIAL EXPOSURE CONDITIONS.* 
 
 Refrigeration......... 2 hrs. 
 Water oa sini ieee 2 hrs. 
 MONnGAY 7 oh. ee eas Industrial Gage. sca 1% hr. 
 | Bates 5! dep: acnaar onan Y% hr. 
 
 Light. .4invs a cate Cee ee 18 hrs. (16 hrs. dry, 2 hrs. wet) 
 Water core i aves eee 2 hrs. 
 Industrial Gas........ 1% hr. 
 Tudsdayins «+ vviais™ | WADEES Avie le oa tee % hr. 
 Refrigeration........<. 2 hrs. 
 
 | Tights AP ERA TAL 18 hrs. (16 hrs. wet, 2 hrs. dry) 
 ( Refrigeration......... 2 hrs, 
 
 Wednesday...... ae Was) ser Pee Ges 4S oes DS DIS. Cre 
 
 LAY Otel oy cocaie keer 16 hrs. 
 
 * For non-industrial exposure conditions, omit the industrial gas exposures 
 and substitute water exposure during these periods. 
 
 vp enn ial 
 
Accelerated Testing Cabinets 339 
 
 . Retrigeration.....:..- 2 hrs. 
 EO Sia be paced Aad ace ee 2 hrs. 
 MRMTSOAY:...>>+- POOUStrisl Gas...-5-.. 1% hr. 
 ti PD UL y epic shi = Dpiinceie'e ce 1%, hr. 
 ALE Sa og ae pare osha, 9 oar 20 hrs. (dry) 
 ( Refrigeration......... 2 hrs 
 Merve sc gie'a vetwie b 8 6.08 2 hrs. 
 SE oy industrial Gas.......«. Y% hr. 
 IE ERNE aha ia Pianos tae oe tw ¢ IN sh 
 oo ne! a aa cai erat te ae 18 hrs. (wet) 
 PRetrieceration.: 2.0. 2 hrs. 
 | We Maes vee ov o.5°s.0 m9 2 hrs. 
 CUE) Industrial Gas........ Y% hr. 
 ea Y% hr. 
 OC i Eo 15 hrs. (wet) 
 Sunday to 
 MONGAY. 24+... ; RNA a: nin’ 9's 635 6 27 hrs. (24 hrs. wet, 3 hrs. dry) 
 
 Finally, a word of warning might not be out of order to 
 those who begin using accelerated weathering tests, for the 
 problem is a complicated one, at best, and many important 
 questions still remain to be answered. For example, the ad- 
 herence of lacquers is so affected by temperature changes 
 that this exposure factor must be handled more cautiously 
 when such materials are under test in order to avoid accen- 
 tuating adherence failures. Additional experimental work 
 is needed to learn where the line should be drawn. It can be 
 said with entire confidence, however, that once some experi- 
 ence has been gained in making observations and handling 
 the equipment, the results will be invaluable to anyone inter- 
 ested in a rapid estimation of the weathering qualities of pro- 
 tective coatings. 
 
 REFERENCES. 
 
 1. H. A. Gardner—Paint Technology and Tests—1911, also Physical 
 Testing of Paint and Varnish, Circular No. 122, Ed. Bureau, Paint Manufac- 
 turers’ Association of U. S. 
 
 2. A. M. Muckerfuss—Preliminary Report upon a Practical Accelerated 
 Test for Paints and Varnishes—Journal Industrial and Engineering Chemistry, 
 Vol. 5, No. 7, July, 1913. 
 
 3. HH. A. Nelson—Accelerated Weathering of Paints on Wood and Metal 
 Surfaces—Proe. A.S.T.M., Vol. 22, Part II, 1922. 
 
 4. Nelson and Schmutz—Further Study of Accelerated Weathering—Proc. 
 A.S.T.M., Vol. 24, 1924. 
 
 » HH. A. Nelson, F. C. Schmutz and D. L. Gamble—Accelerated Weather- 
 ing; Further Development of Apparatus and Exposure Cycles—Proc. A.S.T.M., 
 Vol. 26, Part II, 1926. 
 
 } 6. i. A. Nelson and F. C. Schmutz—Accelerated Weathering—A Con- 
 sideration of Some Fundamentals Governing its Application—J.I.B.C., Vol. 18, 
 No. 12, p. 1222, Dec. 1926. 
 
340 Accelerated Testing Cabinets 
 
 6a. W. W. Coblentz, M. J. Doreas and C. W. Hughes—“Radiometric 
 Measurements on the Carbon Are. ete.”—U. S. Bureau of Standards Scientific 
 Paper No. 539, Nov. 19, 1926. 
 
 7. Oscar R. Flynn—How the Mercury Are was Made to Imitate Sunlight— 
 American Dyestuffs Reporter, Vol. XII, pp. 837-43, Nov. 19, 1923. 
 
 8. William Harrison—Journal of the Society of Dyers and Colorists, 
 July, 1912. 
 
 9. Oscar R. Flynn—Am. Dyestuffs Reporter, Vol. XII, pp. 887-43, Nov. 
 19, 1923. 
 
 10. G. F. A. Stutz—The Absorption of Ultraviolet Light by Paint Vehicles 
 —Paper presented before Division of Paint and Varnish Chemistry, A.C.S. at 
 Richmond, Va., April, 1927. 
 
 11. C. A. Knauss and J. G. Smull—Reaction of Bromine and Linseed Oil 
 in the presence of Ultraviolet Light. Paper presented before A.C.S. at Rich- 
 mond, Va. April 1927. 
 
 all al tet 5 a 
 
CHAPTER XXII 
 
 EXPOSURE TESTS 
 
 The usual purpose of exposure tests is to secure information 
 on the durability of paint products in comparison with those on 
 
 ROOFING 
 
 FIGURE 128 
 
 New Type Test in Washington. 
 
 which durability tests have already been made. Thus, for 
 instance, if a new formula is suggested to replace an existing 
 one, which for many years has been standard, it is to be ex- 
 pected that exposure tests will give some indication of the 
 relative differences which might exist between the two types. 
 The purpose for which a test is proposed should, therefore, 
 be given consideration in designing the test. In this connec- 
 
342 Exposure Tests 
 
 a 
 tion. it is well to point out that tests made upon small panels 
 seldom give the length of life which is observed with the same 
 paint in actual house painting practice. This may be due to 
 the fact that paint is applied to small panels with a small brush 
 dnd a fairly thin film results, whereas paint applied to the 
 side of a house is usually applied with a large brush and a 
 thicker film is obtained which will naturally have a greater 
 durability than a thin one. This condition also accounts for 
 the greater spreading rates that are recorded in paint testing 
 on a small scale as compared to actual spreading rates ob- 
 tained when paint is used on a large job in a practical manner. 
 There are many other variables which enter into the testing 
 of paints on a small scale, and it is doubtful whether such 
 tests can be made the basis of positive statements as to the 
 durability of paints over long time exposures on large struc- 
 tures. 
 
 Wood Panels—In exposing exterior paints upon wooden 
 surfaces, the type of wood selected for the panels should be 
 given careful consideration. It has already been shown by 
 extensive tests now being conducted in sixteen different parts 
 of the United States that the character of wood has a very 
 pronounced influence upon the durability of the coating. These 
 tests have also indicated that different results may be obtained 
 with the same paint upon panels of flat and of edge grain. 
 Whereas a paint may give satisfactory service on the edge 
 erain, it may in some instances show longitudinal cracking 
 upon the flat grain. Tests have also indicated that while 
 paint may give satisfactory service upon a soft, uniform 
 species of wood like white pine or poplar, inferior results may 
 be obtained upon some species of yellow pine; and that red 
 cedar, if not saturated with moisture, may constitute one of 
 the best painting woods. For that reason red cedar panels 
 might to advantage be adopted for exposure tests, since this 
 wood.is now in wide use throughout the country as siding for 
 dwellings. If the object of testing is to show the relative 
 value of various paints, elimination: of faulty lumber is the 
 most important consideration. Red cedar, cypress, white pine 
 and poplar are woods which are obtainable with fairly uni- 
 form grain and all of these different species have been recom- 
 mended by various paint experts. In the writer’s opinion, 
 
 el 
 
Exposure Tests 343 
 
 FIGURE 129 
 
 Newer Type Paint Exposures on Roof of Washington Laboratory. 
 
344 Exposure Tests 
 
 however, red cedar is preferable to the other species men- 
 tioned, provided it is used in a fairly dry condition. 
 
 It would appear that one of the chief causes for failure of 
 many types of paint exposed under severe conditions is the 
 contraction and expansion of the wood panels, caused by 
 moisture absorption and elimination through the unprotected 
 backs of the panels. Under such conditions, the changes in 
 volume of the wood are so great that many paint coatings are 
 not sufficiently elastic after exposure for a year to withstand 
 the stresses developed. Consequently, the films erack or scale. 
 These defects are generally observed when panels are put out 
 without any priming coat on the back or when a single priming 
 coat is used without any additional protection. Wind driven 
 rain striking the back of a panel gradually works through 
 causing volume changes which are soon evidenced on the 
 surface films. This condition is quite clearly depicted in 
 some of the illustrations presented herewith. 
 
 To guard against the conditions referred to above and for — 
 large size tests that are to be continued in one locality for 
 several vears without the necessity of bringing the panels 
 back to the laboratory for examination, the type of construc- 
 tion depicted in Figs. 128 and 129 is suggested. This type of 
 test fence simulates very closely that used in actual house 
 construction, the sheathing applied to the uprights being insu- 
 lated with a sheet of asphalt-saturated felt roofing paper over 
 which the weather-boarding is attached. One exception is 
 that the panels applied as shown in the illustration are all 
 primed on the backs as well as the faces. The type of primer 
 used is discussed later on. The wood used in the test fence 
 referred to is high quality red cedar siding 10 inches wide and 
 6 feet long. 
 
 After carefully selected siding is dried in the laboratory 
 under normal conditions for a period of two weeks to eliminate 
 any excess moisture, the sections are primed all over (front, 
 back and edges), allowed to dry overnight, and then placed 
 out of doors for a week to secure firm, hard dried films. They 
 are then nailed in place upon the test frame, the nail holes 
 puttied and two coats of the white or tinted paint under test 
 is applied, allowing a period of at least five days for drying 
 between coats. 
 
345 
 
 Exposure Tests 
 
 pesn 
 
 spouvd 
 
 ‘UoTpnpoider dTYdBiso.oTMoJoyd PUB UOTJVUTMBxXd IoJ L10}RIOGB]T 0} PoeuINjal puw peAomer ATYonD aq ABU 
 ‘BPHOLA ‘a[[TASouTey UL SeAOIH [IO Suny, Iv YISue, Ul Joey perpuny [VsaAes VvoUT So} JuTed Jo UOTeEg 
 
 OSL aNnDI 
 
546 Exposure Tests 
 
 It is possible that two coats of paint applied over the spe- 
 cial primer used will be much more durable than three coats 
 applied direct to the surface of unprimed wood. Moreover, 
 the use of the special primer which is of pronounced color, 
 affords a surface which only white paints of good opacity 
 will hide perfectly in two coat work. Thus, an idea may be 
 gained of the comparative hiding power of the various test 
 paints being applied. If paints are tested, which chalk with 
 extreme rapidity, or which wash readily, the dark pink color 
 of the primer will soon be evidenced and aid the inspector in 
 judging the life of the test paint. 
 
 Another type of panel (only three feet long) which the 
 writer has recently adopted for panels which are to be exposed 
 in different parts of the country and sent back to the labora- 
 tory occasionally for microscopic examination, is shown in 
 Figs. 130 and 131. This consists of the same type of red cedar 
 siding referred to above treated in the same way, and primed 
 in the same fashion. The difference, however, consists in 
 applying the paints in the laboratory to avoid dust retention 
 or rain spotting during the initial drying period. Hach coat 
 is dried in the laboratory overnight, and the panels are then 
 exposed out of doors between coats for a period of at least 
 five days. After finishing the panels, they are exposed upon 
 a type of frame construction shown in Fig. 130. They are 
 fastened to the longitudinal board with two galvanized iron 
 screws which are later touched up with the special priming 
 paint to prevent corrosion. These screws may be readily re- 
 moved at any time and the panels shipped back to the labora- 
 tory for examination and then returned to the place of expos- 
 ure for further test. 
 
 There exists a wide difference of opinion among experts 
 as to whether test paints should be applied out of doors or 
 within the laboratory. If applied inside and no exterior ex- 
 posure is given between coats, the unhardened undercoats 
 will often cause. checking of the top coats. Moreover, if such 
 panels are exposed out of doors during a winter month when ~ 
 frost and moisture prevail, or in an industrial community 
 where acid gases are prevalent, the semi-soft films will rap- 
 idly take up moisture and washing troubles will ensue. At 
 the same time, it should be mentioned that paints applied to 
 the outside of dwellings in similar months and under similar 
 
Exposure Tests 347 
 
 conditions may also show washing, due to the fact that the 
 films do not receive the hardening which takes place when 
 there is strong sunlight and good drying conditions. It is, 
 therefore, necessary that the time and place of exposure of 
 test panels be considered most carefully. Houses are painted 
 under many kinds of weather conditions in widely scattered 
 
 FHiaurE 131 
 Detail of New Type Test in Florida. 
 
 sections of the country. It would seem hopeless to attempt 
 to standardize upon exact methods of exposure, as they could 
 not always correspond to the conditions which prevail 
 throughout: the country. 
 
 Spreading Rate.—In conducting a paint test, it is usual to 
 determine the weight per gallon of the product under test. A 
 sample of the thoroughly mixed paint is first placed in a wide 
 pint cup and this is weighed together with the brush. After 
 
348 Exposure Tests 
 
 application of the paint, the cup with the remaining paint and 
 the brush are reweighed to determine the amount of paint 
 actually applied to the panel. From the weight of paint ap- 
 plied, the spreading rate can be calculated, based on the num- 
 
 FIGURE 132 
 Paint Failure on Panel Not Properly Protected at the Back. 
 
 ber of square feet of panel surface covered. In some special 
 tests, paints are applied to a definite spreading rate by pour- 
 ing upon the panel a definite volume of paint and brushing it 
 out over the desired area, regardless of thickness or thinness 
 of film. The customary procedure, however, is to apply the 
 amount of paint that is required by the surface and then esti- 
 mate the spreading rate obtained. : 
 
 Angle of Exposure.—It would appear from tests conducted 
 by the writer that if a paint gives good service in an upright 
 
 SA Stew 
 
 :? 
 ~ 
 
 ae as gael ie 
 BR Mee Se 
 
Exposure Tests 349 
 
 position upon weather boarding for a period of four years, 
 the exposure required to present the same condition when 
 exposed at an angle of 45° to the vertical, facing south, would 
 be two years. Thus the period of exposure required to deter- 
 mine the life of a paint coating is cut in half by using this type 
 of exposure. If there is added a cycle of water spray between 
 12 and 1 o’clock every day during the summer months, say, 
 for instance, from April 1 to October 1, the time required 
 to give the same results may possibly be cut down with some 
 classes of paint to a period of from 15 to 18 months. This 
 would then constitute a semi-accelerated test of a practical 
 type. 
 
 — Colors.—If a white paint of a new formula is being tested, 
 it should be applied not only in white but in light tints as well. 
 Light tints, such as pea green, sky blue and light cream, are 
 suggested. Incipient chalking of a white paint is not readily 
 noticed, but chalking of the same paint tinted causes an accu- 
 mulation of the white chalked pigment on the surface, which 
 obscures the tint and gives a faded appearance. The real 
 reason for this ‘‘fading’’ is due to a change in optical proper- 
 ties, such as refractive index, caused by the destruction of the 
 linseed oil at the surface. Thus, for instance, it is well known 
 that a dry white pigment tinted with dry color has a soft, dull 
 appearance compared to the same product wet with linseed 
 oil, which develops a brighter and more distinct color. A 
 white paint base, to be entirely satisfactory, must be one which 
 will tolerate tinting without showing marked fading upon 
 exposure. 
 
 Effect of Climatic Conditions.—If possible, the tests should 
 be exposed under two or more different climatic conditions. 
 Thus, for instance, some paints which may weather quite well 
 in the southern part of the country where high humidity and 
 high temperature prevail might show cracking due to lack of 
 distensibility, in the drier northern section of the country 
 where rapid changes in temperature occur in winter months. 
 Similarly, some paints which wear well in the northern region 
 might chalk too rapidly in the southern region, due to the 
 effects of continued strong sunlight. When ultraviolet light 
 strikes a film, part of it may be transmitted, part may be 
 absorbed, and part may be reflected. If 100 per cent of the 
 ultraviolet light is transmitted, the film should remain in 
 
Exposure Tests 
 
 et 
 
 FIGuRE 133 
 
 Experimental Paints Exposed in Florida for less than 2 years upon boards 4 
 unprotected on the backs except for 1 thin coat of White Paint such as was — 
 used upon the face of the boards. Admittance of water from back causéd crack- 
 ing and sealing 
 
 ¢ 
 <s 
 such as would not occur upon the frame siding of a dw elling, + 
 
 po: ree Aa 
 
 ' Es 
 
Exposure Tests 351 
 
 excellent condition for a long period of time. If, however, 
 part of the ultraviolet light is absorbed, it is changed into 
 ehemical energy and results in reactions in the film, which 
 cause early decay. If a paint contains a pigment which is 
 transparent to ultraviolet light, the hght may either pass 
 through the film entirely or be partially absorbed in the form 
 of chemical energy which may disrupt the film. If the paint 
 contains a pigment which is opaque to ultraviolet light the 
 light does not affect the liquid in which the pigment is ground, 
 and the pigment therefore acts as a protective of the liquid. 
 It has been suggested that zine oxide, for instance, because of 
 its high opacity to ultraviolet light, acts as a protective to 
 paint films in this manner. 
 
 Number of Panels—Wherever possible, panels should be 
 exposed in duplicate, or, as an alternative, boards should be 
 used which would: be of sufficient size to show differing char- 
 acteristics in the same species of wood. If the test is to be 
 a very thorough one, flat grain and edge grain wood might be 
 selected. One method which has been used to advantage in 
 exposing metallic paints might be adopted upon wooden 
 panels. Thus, for instance, a large metal surface is marked 
 off into two surfaces of equal area. Upon one side the stand- 
 ard paint is always applied and upon the adjoining section the 
 paint under test is applied. Thus, the two paints, being upon 
 the same specimen, should give results which can easily be 
 compared. Similarly, a board of sufficient width or a panel 
 of sufficient length to show the irregularities or abnormalities 
 of wood, might be used. Upon one side the standard. paint 
 could be applied, while the adjoining area could be coated 
 with the test paint. This could be done without a special 
 primer if the object is to show the ability of a paint to wear 
 well over any species or grade of lumber. 
 
 Inspections.—Examination of the tests should preferably 
 be made every three months. <A record of the results on a 
 blank form should be made at least every year, and preferably 
 every six months. The inspection can be made in accordance 
 with the standards of the American Society for Testing Ma- 
 terials, which are given below. The method of rating gloss, 
 which heretofore has been largely based upon visual examina- 
 tion, can be determined on removable panels with the Inger- 
 soll glarimeter. 
 
wie Exposure Tests 
 
 Primer Paint for Tests——As has been referred to above, 
 the failure of many paints upon wooden surfaces is very often 
 due to the character of the wood, the moisture content, and 
 to the absorption and elimination of moisture by unprimed 
 or poorly primed surfaces. These conditions can be very 
 largely prevented by the use of a metallic primer. Some of 
 the primers that have given excellent service for this purpose 
 are given below: 
 
 RED LEAD PRIMER NO. 1 
 
 Red Leadie. icc uc. eels wees «suo on eile Oe 100 ~—s lbs 
 Raw Linseed Oil... 6... coe a ce oo a eeleere ore ae 15. Ths 
 Turpentine: 0.26 6.5000 6 swols «us wb 0 olla een 2 Ibs 
 0) ol :) ern RP i Sib, 
 
 Zine Dust ». 2... cewh wake ecb cle wae ule cree 45. Ibs. 
 
 Bin OXIde os cc. oceis ss 5 ee ule «a le) ene 20 sibs. 
 Boiled Linseed Oil ........ 5020.0 bos seen 25 Ibs. - 
 Turpentine foci sce cwe coves ude 5 5ie oie een 6 Ibs. 
 | Oe (:) EPP 4 Ibs. 
 
 ALUMINUM PRIMER NO. 3 
 
 Tung Oil Spar Varnish (Long Oj!) 7..72..90 ee 5 - Tbs, 
 Boiled Linseed. Oil. i. 60.4... 0 os os bee 17th 
 Turpentine ©. 0... << ssw us ulna ee tn eee 1 AB. 
 Aluminum Powder ... 0.01.0. sces «sks See 1% Ibs. 
 
 Red Lead ...6..0se.000c enced eos onus Otten 12 Ibs: 
 Aine “Dust 3... ssG sce eee Seb ww te ce eee Eee ee 2 Ths 
 Aluminum Powder ..........<0% © 2s pagers | 
 Linseed Of] ...% .neeces vs cen sy 6 5lpnel eee enn 2 = ats. 
 Boiled Linseed Oil .....:...%.<. «5 «20 ble 1 ee 
 Turpentine 2666 sean i see a ewe oe nies eee ee 1: pS 
 Turpentine Liquid Drier ......2..455 252 % gill 
 
 Of these primers, the writer prefers the last one, inasmuch 
 as it produces an extremely flexible film of the desired degree 
 of hardness and water resisting properties. While it is true 
 that an aluminum primer alone has given satisfactory service, 
 this product is generally made with spar varnish which tends 
 to become brittle after a number of years. If boiled linseed 
 oil or heat-treated oils are used in such paints, the drying 
 time is so retarded by the aluminum powder that it may be- 
 come unsatisfactory as a primer. The use of red lead with 
 the linseed oil-aluminum powder mixture gives to the film a 
 quick drying characteristic, soundness, and pore-filling prop- 
 erty that seems to be extremely desirable. The addition of 
 
Exposure Tests whi! 
 
 the zine dust, which can be added to a paint in concentration 
 without greatly increasing the body, has also proved desir- 
 able. It would also appear from the results of some storage 
 tests upon this tri-metal type of primer paint that it will re- 
 main in usable form for several months, without showing 
 hardening. Thus, for instance, a comparison was made over 
 a period of four months of a stored red lead paint containing 
 30 pounds of red lead per gallon of linseed oil and Formula 
 No. 4 as shown above. The straight red lead paint in the 
 period referred to had become stiff and almost unusable, 
 whereas Formula No. 4 remained soft and easily brushable. 
 This might suggest experiments in the direction of the pro- 
 duction of a red lead primer of this character, which could be 
 kept in prepared form for long periods and used not only 
 upon wooden surfaces but also upon all metal surfaces where 
 it has extremely desirable properties as a rust preventive. — 
 
 In order to secure information as to the relative absorp- 
 tion of moisture by panels primed with aluminum and with 
 the tri-metal type of primer, a series of tests were made upon 
 one foot square panels of red cedar siding which had been 
 brought to a uniform condition. Some of the panels were 
 exposed without primers. Others had one coat of aluminum 
 paint No. 3 and others had one coat of primer No. 4. After. 
 exposure on the roof for 24 hours, during which there was 
 a rain storm lasting two hours, the plain panel absorbed 8%, 
 the aluminum panel 1.7%, and the panel primed with the tri- 
 metal primer No. 4, 1.4% of moisture. After drying the 
 panels upon the roof for a period of two days, they were 
 sprayed with water for a period of 8 hours. The plain panels 
 absorbed from 13% to 18% of water. Those coated with 
 Primers Nos. 3 and 4 absorbed less than 3%. It can readily 
 be seen from the above that by limiting the amount of water 
 that can get into a panel to as low as 3%, it is possible to pre- 
 vent great volume changes in the wood. It is also apparent 
 that the tri-metal primer is quite as effective as the aluminum 
 primer. | 
 
 A. 8. T. M. Method for Reporting Condition of Exposure Tests—It is im- 
 portant that uniform, precise and relatively accurate methods for describing: 
 or measuring the character and amount of disintegration of paint coats be 
 adopted. Unless such standards are evolved, reports made on the wearing: 
 yalues of paints by different investigators or observers cannot be intelligently 
 or accurately compared. 
 
354 Exposure Tests 
 
 In considering the adoption of definitions for terms generally used in report- 
 ing condition of painted surfaces, descriptive words now in common use have 
 been adhered to. In addition, an effort has been made to assign numerical 
 values to these descriptive terms with the idea of ultimately working out some 
 scheme whereby paint tests may be given a definite rating. A great deal of 
 study is still required in order to assign values to the descriptive terms, so 
 that the final rating may not only be an accurate one, but that it may really 
 represent some well-balanced and understandable relative measure of service 
 value. 
 
 Checking.—Checking describes slight breaks in the paint coat which do not 
 extend through to the surface painted. This is reported and rated as: 
 
 ADSONE og 5c bs doe Sou soaie’ e's be picasa ate Saree os ete 10.0 
 
 Very Slight oo. occas ce eco ay 0s om aillele oe 9.9 to 8.0 
 Slight . i.'6.40 ks e's oe w hae © ok eo ee 7.9 to 6.0 
 Considerable | ...c:66 6 + a0 .o-4 ms ecnus a9 sole sien 5.9 to 4.0 
 1$1:1) Ere eS here $9200 20 
 Very Bad asic acs oon bes asco shales 0's anes aie eee 1.9 to 0.0 
 
 Alligatoring.—Alligatoring describes an aggravated form of checking. The 
 breaks in the paint coat are wider than in checking and usually extend almost 
 through to the surface painted. While the condition is seldom observed, it is 
 advisable to include the term “Alligatoring” in the list of definitions. This 
 condition is reported and rated same as for “checking.” 
 
 Cracking.—Cracking describes a break which extends down to the surface 
 painted. It may be a break which immediately extends down to the surface 
 painted or it may be the development of what was first checking or 
 alligatoring. 
 
 On wood, cracking is usually parallel with the grain, although sometimes 
 it is at right angles to the grain. This condition is reported and rated same 
 as for ‘‘checking.” 
 
 Flaking.—Flaking describes the falling away of small pieces of the paint 
 coat. This type of disintegration is generally the result of checking which 
 gradually develops into cracking, ending in the crumbling of the paint coat. 
 This condition is reported and rated same as for “checking.” 
 
 Scaling —Scaling describes the breaking away of pieces of paint of con- 
 siderable size. This condition is generally the result of long cracks, on wood, 
 usually parallel with the grain. This condition is reported and rated same 
 as for “checking.” 
 
 Blistering.—Blistering describes a condition where the paint coat is de 
 tached and raised from the surface over which it is applied, due to the forma- 
 tion of gases beneath the coating, influenced generally by moisture behind the 
 coating. 
 
 The breaking of the blister results in peeling of the paint coat. 
 
 Peeling.—Peeling describes the pulling away or falling away of large pieces 
 of the paint coat from the surface to which it was applied. 
 
 Peeling of paint is not the result of natural wear, but is due to improper 
 application or to adverse conditions at the time of painting, such as moisture 
 behind the paint coat or a faulty application of the priming coat. 
 
 Gtoss.—Although much depends upon the nature of the coat, it is not advis- 
 able to report condition of gloss after a paint has weathered for more than @ 
 
Exposure Tests OS 
 
 year. The gloss which a paint had shortly after its application disappears 
 in proportion to the chalking of the paint, and while it is possible to restore 
 a gloss to a surface in some cases, by rubbing, the gloss restored is the result 
 of abnormal treatment. Gloss may be reported as: 
 
 MRT Otero Winey odio sis\e cd ue eas ves ceeess 10.0 ; 
 eta. Sipla c's cc. ¢ eves 04 008 Une es 0 0 9.9 to 8.0 
 EE are eet, 6 a0e Bice oo ois plas Se els eye oe 8% 7.9 to 6.0 
 te ig alu crsia bic clas «sis'é vo se aenscceae 5.9 to 4.0 
 TI fine ayes. 5s ce Hew sb 3 tok 06 eed eee es 3.9 to 2.0 
 ee i cass se fee ce ees lseveweases 1.9 to 0.0 
 
 Chalking.—Chalking describes the reduction of the outer surface of the 
 paint coat to a powdery substance, which may be removed by rubbing the 
 coating with the dry finger, or a piece of soft, dark colored cloth, preferably 
 black velvet. This condition is reported as follows: 
 
 Absent Considerable 
 / Very Slight Heavy 
 Slight Very Heavy 
 
 It is a difficult matter to assign uniformly satisfactory ratings to the quali- 
 fying terms and, therefore, while the report should include the item of 
 “chalking,” it is considered advisable to eliminate ratings. 
 
 Hiding.—Hiding is judged entirely by the degree of concealment of the 
 surface painted. This property is frequently referred to as “covering” which 
 more correctly applies to the area over which a given amount of paint will 
 spread. Hiding is reported as follows: 
 
 SOU yee lays t bp sone vie soa 0ve 00 60 tse 6 06 400 10.0 
 
 MEI ae ac so sia ss cee s cs ces cede swede 9.9 to 8.0 
 EN eS Fi aa oie e's do ois oleic eo vee bwecteees 7.9 to 6.0 
 eS 5 Sle eG. u wb 6b bela ele aie ecm 5.9 to 4.0 
 RM ee Sets ok ee ee a vis ee tee eee ees 3.0 to 2.0 
 MINUET Eee 2. lg is cole ese te Ce eae dea oe Mos 1.9 to 0.0 
 
 Color.—Paints are divided into three classes, whites, tints, and colors. 
 The degree of whiteness determines the character of report for the first class. 
 Two things generally influence color; first, the hiding power, and second, 
 chalking. Invariably a paint that chalks presents a better color than one 
 that does not. The impression gained through the eye serves as the basis for 
 report regarding the color of paint. The original appearance need not be 
 considered. While all colors show a natural fading out, some retain a pleas- 
 ing tone while others appear distinctly muddy or lack the brilliance shown 
 when first applied. The terms used for reporting color are: 
 
 Very Good Poor 
 Good Very Poor 
 Medium 
 
 It is not considered advisable to assign rating to the descriptive terms. 
 
 General Appearance.—The general appearance of painted surfaces can 
 really be determined only by viewing them from a distance of twenty or thirty 
 feet, with the idea of forming an opinion as to whether the appearance is 
 good, which will be influenced by such conditions as cracking, scaling, chalk- 
 ing, and other conditions usually found in paint wear. 
 
356 Exposure Tests 
 
 Forest Products Laboratory Tests on Painting Lumber.— — 
 Extensive exposure tests have been conducted by the Forest 
 Products Laboratory in practically all climates represented — 
 in the United States. In these tests eighteen different kinds — 
 of soft woods in edge grain and flat grain were exposed at — 
 
 ai et Sige ea iets Meares rt 5: 
 
 pioneers pebben naar 
 
 FIGurRE 134 
 
 An early stage in the development of paint slits. 
 (Magnification about 2 diam.) 
 
 eleven different exposure stations. They were painted with — 
 two different types of paint, including pure white lead and a 
 paint containing 60% white lead, 30% zine oxide, and 10% 
 inert pigment, Some of the results of these exposure tests — 
 
JOT 
 
 Exposure Tests 
 
 8 IZ i CS 0 96 SF '  (sisuayayis da01d) sonids ByiIS 
 LL ze 0 F 0 se 8G ‘CCC (sisuappund Dad1g) aNnAdS 91TU AA 
 ite oP 8 CZ 9 eS SF "(oi hydosazay DONS [,) MoO[WIY Uld1S89 AA 
 6L rh 9 ZL 0 18 9L _(spitepoune DOns1) YOO[Wey UlajSVq 
 0 p 0 0 0 OOL 93 Ce cee eee eee (Duniuos 
 ner Ore $2. spd hoanwDYy D ) IBp9M PIOJXO WO 
 0 OL 0 $ 0 OOL SF Cc (sisuaq 
 -DY}J00U = SiundfisaDWDYO) <ABpI. BYSBlTW 
 
 0 LI v cL i 96 SF °° * (vyp07)d vinyT) ABVp9Id pet U4e1SIM 
 (0) + 0 A 0 OOTL 2 basis a gad (suamasaduas vionbagy) pooMpesy 
 ) 8 0 9 0 86 SV eis es “ (unyosip wniporny,) SSetd&p 
 66 9¢ GG cS SG 09 8h °° (81D]Uapws0 LMT) YoABl UII{SIM 
 Lt 9S 66 VS 61 09 SP” "Conofren} DONSjopNasd) AY Se[snod 
 SL 66 LI TP OL 62 SF ttt ts (40209U00 sa1gyV) AQ 2M 
 OL 1A ( 6. 0 <6 SF °° (pjoojwow snug) 8UId a} UW19}S9 AK 
 cT Lz OL cS 9 06 rt ets el ""**(sngoss smutq) ourd aT 
 5 GG G S&S 0 6 2 ee wae (DUDIqAIQUD] SNu_) 2UId IBsNg 
 at && OT LY as pe OL 98 (Vsosapuod sniig) ould MOT[eA U1981S9A4 
 Sc 9& 8& G9 LG Fg 8b Cds snug) ould Moles Ulayjnog 
 
 payoyy subis up paymy subis fiuy pog 40 400g ~ pooyy sjauvd fo poom fo puy 
 
 —burnoys sjaund —bwunoys sjauod —sp pappoib sjauod 49QUINnU 
 {0 U9) dad {0 qUWa0 dad {O 7U29 dad 1010.1, 
 
 UO1DADIIWISUT a0unsvadd Fy 
 poom fo 
 LUIYIOYD 4OYIDI AM —0}] Joadsad Ypiar 
 
 furjvoo quripd fo uoriprpuog 
 
 SGOOM UNGYHdIAId NO INIVd JO AHOSOdXaA SUVAA OME AO SLTIOSHU— St WIAVL 
 
es ee RS ee a ee ee eee Ee ee ae eR ee ee ee ee a see eh ae: ee 
 
 - 6 II ae S 88 +9 Seb Ie pe Bis 88 Eig. o(h re Mo R Seen mfototal Sits atwalerp a MEANT Aig ahe UM id su8le tial tara AOE, uoySUTYSE ‘aqyyeeg 
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 ¢ o¢ fT 9S 6 08 £9 Ris (918, Wisin Sib ib) a-pI9b/ So diw iss org’ agian tle 8 b/d.d.3 olen wie elms Mialaic e's] s1e0a'6.00 Mia edacew elusopied ‘ousoL 
 6 KY SZ OF Sy4 | L9 $9 AKAM Sin te Meswe SeuereguNs eh tp mieiehal boa ss Sie’ nai dyi ais ofa, sYaredn ap arta ooabatuse A veal bse onal euozIly ‘woson J, 
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 Bw 6 €Z 6 LZ 0 66 FQ tiretergteerersterenseh rend tes pets ceesoncneetearnmnts UISUOOST AA ‘QoNeMII| 
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 (e) . 
 Q payavpy = SusIS Kup =payavpy Suds Kuy pog 40400g poo 
 a $$ sjaund fo UOUDIS aANSOGXT 
 Ry —SuUIMOYSs Sjaund —suimoys sjaund —SD pappis sjaund 4aquinu 
 f0 ]UI2 40g fo juar sag fO Jua9 ag 1040] 
 UOUDABIJUISLT aounavadd f 
 poom fo 
 BULYIIYI 4dYIDA MY —0] qoadsaa yyum 
 
 BUuUNDOD Juv fo UoYytpuoy 
 
 YNIGVGHIVAM GOOM GNV SONLLVOO LNIVd NO ALYNIIO WO QONGTOANI—6F GIAVib 
 
 358 
 
Exposure Tests 359 
 denne ee ee 
 are shown in Figures 134 to 136. For a detailed consideration 
 of these tests, reference should be made to the original re- 
 port.* Two of the interesting charts appearing in this origi- 
 nal report are presented as Tables 48 and 49. 
 
 FIGuRE 135 
 
 Discoloration of a paint coating at Gainesville, Fla., due to the growth 
 of lichen and sooty mold. It is claimed that by using less linseed oil and 
 more turpentine in the third coat paint for such climates the danger of 
 ) 9 alee ia of this kind can be very greatly reduced. (Magnification about 
 
 diam. ) 
 
 * “Painting Characteristics of Woods,” by F. L. Browne. Scien. Sec. 
 Cire. No. 219. 
 
360 Exposure Tests 
 
 by 
 FER NRE 
 
 FIGURE 136 = 
 
 The paint coating tearing loose from the wood in long shreds in the veryia 
 dry climate of Tucson, Ariz. The long slivers appearing in the photograph 
 are pieces of the paint film, not of the wood. . ie 
 
 one 
 
Exposure Tests 361 
 
 FIGURE 137 
 
 Section of the Forest Products Test Fence at Gainesville. Panels on left 
 coated with white lead show more fungus growth than those of Lead-Zinc 
 Paint on right. This test shows importance of conducting tests in various 
 localities in order to subject paints to local conditions. 
 
362 Exposure Tests 
 
 Service Tests on Varnishes.—During the past few years, a 
 committee, of which the writer has been chairman, has con- 
 ducted a series of exposure tests on varnishes. ‘These are 
 fully outlined in the Proceedings of the American Society for 
 Testing Materials for 1925 and 1926. Included in these tests 
 were maple panels, black japanned panels, plain black iron 
 panels, and glass panels. The black japan used for priming 
 the panels was an automobile fender enamel baked for 46 
 minutes at 450° F. After application it was rubbed with 
 pumice stone and water. It was believed that one might ob- 
 tain the maximum life of long or short oil varnishes upon such 
 japanned panels up to the time of the first cracking of the 
 varnish. It was found as a result of these tests, which were 
 exposed under the same conditions and for the same period 
 of time in different parts of the country, that the reports 
 were all in agreement in so far as the elimination of wood 
 and glass panels was concerned. These did not give uniform 
 results. The black japanned and black iron panels, however, 
 gave fairly consistent results. The exposures over some of 
 the black japanned panels showed a lack of adhesion between 
 the japan and the varnish, which might possibly have been 
 overcome by baking the japan at a lower temperature. On long 
 time exposure, the plain unsurfaced black iron panels showed 
 a tendency to rust, which interfered with the inspection. As 
 a result of these tests, however, further tests were conducted 
 during the past year, in which more permanent types of 
 panels (relatively rust-free) were included. These included 
 cold rolled steel as well as black iron (having a smooth, ad- 
 
 herent blue mill scale). Similar panels which were finished © 
 
 with a black tung oil spar varnish, subsequently baked, were 
 also used. There were also included cold rolled steel and 
 black iron panels which were plated in the following manner: 
 
 Nickel film .001 inches. 
 
 Copper film .005 inches, then nickel .0005 inches. 
 
 Chromium film .0004 inches. 
 
 Nickel film .0908 inches, then chromium .0002 inches. 
 
 While results are not available as yet on these panels, the 
 
 indications are that varnishes which crack upon the plated 
 panels are more apt to show peeling at the same time than 
 varnishes applied to black iron or japanned iron panels. It 
 is felt therefore that the latter types of panels are best suited 
 for varnish exposures. 
 
363 
 
 Exposure Tests 
 
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Exposure Tests 
 
 364 
 
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 Exposure Tests 
 
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FIGURE 144 
 
 Photomicrograph of surface of 
 an interior rubbing varnish. Sur- 
 face was scratched with a needle. 
 Note clean cut effect due to hard 
 
 film. 
 
 FIGurE 146 
 Photomicrograph of surface of 
 exterior spar varnish. Surface was 
 scratched with a needle. Elastic 
 and comparatively soft nature of 
 film indicated. Also note dark 
 spots due to particles of  poly- 
 merized oil that have become in- 
 soluble. These particles are often 
 the cause of a “sandy” surface. 
 
 Exposure Tests 
 
 FIGURE 145 
 
 Photomicrograph of surface o 
 an exterior spar varnish. White, 
 cloudy effect caused by immersion 
 in cold water. Water has not 
 abraded or injured film but has 
 
 possibly formed an emulsion with 
 the outer layer. 
 
 FIGURE 147 
 
 Photomicrograph of surface of — 
 an interior oil coating showing — 
 effect of boiling water which has — 
 caused the film to “creep” or pull — 
 away from the surface, leaving — 
 crater-like bare spots. To the | 
 naked eye a white and rough sur- 
 face is indicated. 
 
Exposure Tests 367 
 
 FIGURE 148 
 
 Photomicrograph of surface of 
 an oil coating that has shown 
 peculiar crinkling, probably due to 
 surface tension effects. 
 
 FIGURE 150 
 
 Photomicrograph of a drawn 
 metal article. Note abraded effect 
 of metal. Rapid corrosion would 
 follow unless protected with paint 
 or varnish. 
 
 FIGuRE 149 
 
 Photomicrograph of a paint 
 coating. Thinner used in the paint 
 was too volatile. Upon evapora- 
 tion from film, it caused formation 
 of small craters. 
 
 Figure 151 
 
 Photomicrograph of a paint coat- 
 ing. Paint was not properly ground 
 in mill. Note rough, granular sur- 
 face of unground pigment particles. 
 
368 Exposure Tests 
 
 FIGURE 153 
 
 FIGURE 152 
 Photomicrograph of a wall coat- Photomicrograph of an experi- 
 ing. Drying in a dusty room mental flat coating. Paint con- 
 caused adherence of dust particles. 
 a darkened 
 
 tained too much volatile matter, 
 These gave surface Scratch made with a metal point 
 shows dry nature of film. 
 
 appearance. 
 
 FIGURE 154 
 
 Photomicrograph of a cross-sec- 
 tion of an enamel coating on oil- 
 cloth. Note warp and filling 
 threads of cotton fabric, filled sur- 
 face, and smooth outer’ white 
 enamel film. 
 
Exposure Tests 369 
 
 Testing the Rust Inhibitive Value of Pigments for Metal 
 Paints.—In some fairly comprehensive tests carried out by 
 the writer in 1908 in Atlantic City, under the auspices of the 
 A. S. T. M., several hundred steel and iron panels 18 x 36 
 inches and of 18 gauge were employed. In this test the 
 specific gravity of the pigments was determined, and a defi- 
 nite formula for the grinding was then decided upon, so that 
 the same amount by volume of each pigment would be used 
 with the same quantity of oil, viz., specific gravity of pigment 
 X 3 = lbs. of pigment to gallon of oil. The pigments were 
 ground separately in a mixture of two-thirds raw and one- 
 third boiled linseed oil, no drier or thinners being added, be- 
 
 CONDITION OF PAINTS. AFTER FOUR YEARS’ EXPOSURE. 
 Rating 
 
 1913 
 
 Panel Pigment 
 MEV CTINIION ook ecg cee ce ce ete ve ch tee veateneas 9.8 
 Demeromemie edd CHTOMUte 26.6. we ec ccc cee ee ete 8.3 
 TON Q UG oo ae vce ee cc ew sce ve wes a eeecuveses 8.0 
 CS AFCOAL, fs... so cp ka ee ec eek eevee ete e es tuewess 7.9 
 Been tarium Chromate ....... 2.2.02. ese een eee etes 7.8 
 Rete gC XING on. ee cca b eee eee w ed cuuduceteucs 7.8 
 4] eT et LIE TOTLC). 6... ccc cee eek oo e bulee eee ecauss 7.6 
 5)  Sublimed Blue Lead (Basic Sulfate—-Blue Lead)............ 2 
 eee orpeneeiack (natural barytes) ...........0..00.00 een ae 6.8 
 SV. ac ee bcs Po be Wee tdewbeeeecuereaie 6.7 
 Ne ON PY, oo ewe cle cw ee cece eee ewe ceuuedubaces 6.3 
 MIE ITG ee ccs wine Bee vee ct te tedeweties Es 
 SunrrarectmeeMetallic: BOW ......- 2. cee ee ewe eee cee eceeeses 6.1 
 IPMN MMICTIM AVI TCA oo... es ln wc cw eee cece cen sccescsecaswe 5.9 
 Ge elljw. OCHKC. ..... 00. cece cde e nce eevee etue wentwoee De 
 eee Tirome. YELLOW ...-.... 00s decccpceecewawevneedue n2 
 ET Dh ks ccs a ck vieen rsp ce edueg gen daeeuawes 5.1 
 ME ee, cok. dw taney cy wc wees ae bole aewaat 5.0 
 SS 6 iy rr rr re 4.5 
 DEIR TC OAEVECS) 0. ic ce esc cee ceed eaebccdwavauives 4.2 
 Peewee Qranze Mineral—980% Pb,O, ....2..-.0-.use cnc ees 4.0 
 IN AE ls eek es ce ced caucelevieectious Bio 
 IEE EQUIPO wo heck co Wace casceheavega vasckuncds 2.6 
 1 Semester OCeee eV Hite Lead. oo .2. ec ec ce ce etl bn veces cen nes Lo 
 meme reece White LOA)... .....- ec cc cccscee ceseceucevcce ‘bee 
 I SSVI)... 0 ose lec cs oct cde ccwecsvccciacaat Ne: 
 memaevedine (magnesium silicate) .............cececccccccucccs A Mee 
 MR ro he esos kd selec b A ve ve ba ede k eels 0.8 
 IT es sg cine sin bok ek Queled vale lon cdelaweas 0.4 
 ME MINCE POUL ELATVLOS oc, 0. fs caia wc bse a bicndaevbaecebiccsonennun 0.2 
 MITER ACO) 2s os cs eine wn vod Sb els wow baa ee Obece 0.2 
 MEMEMISIUEAPVIPS 0. ws. cin ace enss cc ccs eavictlbacccleecsecene 0.1 
 Seater Carbonate (whiting)  ........c....cene vec caventeccn 0.0 
 meeeetcinm Carbonate (precipitated) ......s.0+.c.cscacececccce 0.0 
 MINER TRIO BUC. bos k hci > ove eos bs baba vcvldavcdhadhen 0.0 
 
 * Contained about 7 parts Barytes to 1 part Black by weight. 
 
370 Exposure Tests 
 
 cause of the unknown factors which would be introduced by 
 the drier content.* 
 
 The paints were all applied at a definite spreading rate of 
 900 square feet per gallon on three types of iron or steel. 
 
 At the end of four years, certain definite results were 4 
 shown, the report of the committee as of the fourth annual — 
 inspection being presented below, 10 being the highest rating, 
 zero the lowest. 
 
 FIGURE 155 
 
 Members of Educational Bureau and Inspection Committee at 
 Atlantic City Panel Tests during spring of 1910. In these tests 300 
 steel and iron panels 18” x 36” in size were used. The use of panels 
 of such large size affords a more practical “brush-out” test than 
 
 where small panels are used. For details of test see Scientific Section 
 Circular No. 202. 
 
 * The above method gave satisfactory paints in almost all instances. With 
 zine oxide, however, the paste was so thick that it was necessary to add 170 
 grams of turpentine to 1000 grams of paint to bring the paint to working ~ 
 consistency. This feature, together with the low oil content of the paint, 
 was no doubt responsible for the relatively poor showing of this pigment 
 which requires a long oil reduction in order to obtain satisfactory service. 
 Similarly with bright red oxide, the addition of turpentine was required. 
 
Exposure Tests 371 
 
 FIGURE 156 
 
 Type of construction used in Atlantic City, Pittsburgh and North 
 Dakota tests made several years ago. Modern tests should have panels 
 at 45° to the vertical to accelerate exposure. 
 
 FicurE 157 
 
 Old panel exposure tests back of laboratory. 
 
 Preparing Metal for Painting —Sub-Committee XIV on 
 Preparation of Iron and Steel Surfaces for Painting, of the 
 American Society for Testing Materials, exposed a series of 
 panels during February 1917, to determine the difference in 
 wearing properties of paints upon steel surfaces prepared by 
 different methods. The tests were exposed at Altoona, Pa., 
 and Brooklyn, N. Y. <A preliminary report of the Committee, 
 presented in the 1921 Proceedings of the Society, contained 
 the following statements: 
 
372 
 
 Exposure Tests 
 
 ‘‘While the tests are not completed and final concly- 
 sions are not offered at this time, there are certain in- 
 
 dications that are matters of such importance that it | 
 
 seems desirable to report them. These are the follow- 
 ing 
 
 “1. The thorough methods of preparation, 7. e., sand 
 blasting and pickling, show no superiority in general over 
 
 ordinary methods of cleaning the surface by scraping, — 
 
 wire brushing and wiping, where corrosion has not com- 
 menced or has only moderately advanced. This applies 
 to both new steel and old steel which has been in service. 
 Test No. 10 indicates that where corrosion has advanced 
 greatly, ordinary methods do not give satisfactory re- 
 sults. 
 
 ‘*2. Weathering to permit loosening ‘and partial re- 
 moving of mill scale, with ordinary methods of cleaning 
 before painting, is detrimental to preservation. 
 
 “3. Painting in a cold dry atmosphere results in pres- 
 ervation as good as painting in warm dry atmosphere, or 
 on heated steel. (This may be due to the greater thick- 
 hess of coatings applied in the cold atmosphere. See 
 spreading record of coatings.) The appearance of the 
 coating may be impaired by shriveling and wrinkling. 
 
 ‘4, That sand blast cleaning may give better results 
 than pickling is indicated by the panels exposed at Brook- 
 lyn. There is no appreciable difference observable in 
 the panels treated by the two methods and exposed at 
 Altoona. | | 
 
 ‘‘o. The exposure of sand blasted and pickled surfaces 
 for the development of incipient rusting before painting 
 may be detrimental rather than beneficial, as indicated 
 by the results of test of pickled plate at Brooklyn. 
 
 ‘6. The preparation of old painted steel surfaces 
 
 which have bare rusted spots, by brush coating with ben- — 
 
 zine over and around the rust spots, burning the benzine 
 off and then scraping and wire brushing, gives better re- 
 sults than scraping and wire brushing without the benzine 
 treatment. Where any considerable amount of surface 
 requires treatment, the comparative cost of the method 
 and of sand blasting should be considered. 
 
 “7. There is no difference observable in the results of 
 the application of the same methods to old and to new 
 steel.’’ 
 
 Apparently more positive results were obtained at Brook- 
 lyn than at Altoona, the report of the fifth inspection, as of 
 
 Oe eer 
 
Exposure Tests 373 
 
 Noy. 25, 1922, being appended hereto. While no positive 
 conclusions have been drawn in connection with these tests, 
 the information presented will doubtless be of interest to those 
 having to do with the application of protective coatings. 
 
 TEST ON NEW STEEL, BROOKLYN 
 Description 
 
 Rating 
 Panel No. 1. Clean ‘surface, mill BOLIGIINT ACL hs BAeea teeta taut. 60 per cent 
 “No. 2. Mill scale broken; some rust; hand cleaned...... 40 %: 
 _ No, 3. Sand blasted } 50 re 
 “No. 4. Sand blasted | Various conditions of atmosphere | 25 a 
 “No. 5. Sand blasted and temperature at time 40 re 
 “No. 6. Sand blasted of painting 80 ke 
 | 2 $0... 7.* Sand blasted | 60 Ke 
 Panel No. 16. Incompletely sand blasted.............. hannah 65 per cent 
 ree SS, Pickled, hot water rinsed, neutralized, water 
 TS ya i ee a Rg 60 % 
 ~~ Mo, Qo* Pickled, cleaned as for Panel NOMS awe ae Eon 2 
 olen ae Pickled, washed with cold water under pressure. 25 a 
 TEST ON OLD STEEL, BROOKLYN 
 Description Rating 
 Panel No. 12. Cleaned with ‘idle 2S ELV IRE eae le cae (Re 40 per cent 
 “ No. 13. Cleaned with benzine, scraper and wire brush. He ot) - 
 No. 14. Benzine applied and burned with torch; cleaned 
 with scraper and wire brush................ 80 ¢ 
 See etd blasted 2... tt 40 3 
 
 In the 1926 report of this Committee, the ratings of the 
 panels were given. Among these ratings were the following 
 which were obtained upon new steel panels, surface treated 
 in various fashions. A rating of 100 is highest, a rating of 0 
 being complete failure. 
 
 CONDITION 
 
 RATING 
 
 PER CENT 
 
 OCTOBER 
 
 PANEL SURFACE CONDITION oR TREATMENT BEFORE PAINTING 15, 1925 
 
 NEW STEEL PANELS. 
 
 No.1 Clean surface, mill scale intact, painted in warm dry room 10 
 No. 2. Mill seale broken, some rust, hand cleaned, painted in warm 
 MEM s ee he i ee ene pa 
 No. 3 Sand-blasted, painted immediately after in warm dry room . 80 
 No. 4 Sand-blasted, heated in oven to 225° F. and then painted.. 35 
 No. 5  Sand-blasted, placed in cool damp room 40 minutes and 
 MME ee rete Gh coi. Spy Sh he Wee eee: 84 
 No. 6  Sand-:blasted, placed outdoors and painted there at a 
 ReemeerrresOt: Ob ety O77 We le ie 84 
 No. 7 Sand-blasted, exposed out of doors for 7 days, painted over 
 Meme ar ITY TOO) |. m4 oc Sas bck cen oo ks 55 
 No. 8 Pickled, painted in’ warm ODWr SOOM elt Cnete teeta ere ee 84 
 No. 9 Pickled, exposed out of doors 7 days, painted over rust in 
 REM OO on girly nga cus hgh oalhe edie ive c ek waa hy ees 50 
 
 *Seven days’ exposure to weather before painting. 
 
374 Exposure Tests 
 
 Testing Metals With an Accelerated Roof Exposure Tank.— 
 A type of test devised by the writer for determining the re- 
 sistance of plain, galvanized, and painted iron conductor 
 pipes such as are used for rain spouts and leaders upon build- 
 ings, is shown in Fig. 158. It consists of a large metal tank, 
 96° long, 25" wide, and 9” high, constructed of galvanized 
 iron and thickly coated on the inside and outside with a heavy 
 coating of acid resisting bituminous paint. On one side of 
 the inner surface is placed a wooden rack eut out to serve as 
 a support for the pipe or other test specimens. This rack is 
 so arranged that when the specimens are placed in the tanks 
 
 FIGURE 158 
 
 View of tank tests on roof, showing painted pipes semi-submerged 
 at angle in corrosive liquids. 
 
 and the tanks filled with liquid within an inch of the top, one- 
 half the inside and one-half the outside of each pipe will be 
 submerged at an angle, the other half being exposed to the 
 air. To accelerate this test, cut-up sections of asphalt shin- 
 gles of various kinds and a series of red cedar and cypress 
 shingle splinters about 6” long and %” wide, are submerged in 
 
Expcsure Tests 375 
 
 bundles. Continuous leaching action of the water upon these 
 splinters will to some extent duplicate the formation of sub- 
 stances which would be evolved from roofs by rain water. 
 Metals exposed under these conditions, especially when salt 
 water is used in the tank, corrode with great rapidity. A 
 few of the specimens exposed, together with a chart of some 
 of the results obtained, are shown below: 
 
 FIGURE 159 
 
 View of exterior of No. 1 Unpainted and Nos. 2, 8 and 9 Painted pipes that 
 
 were in accelerated salt water test. Note how corrosion has occured mostly 
 
 at the water line where air is absorbed by the salt water and greatly stimu- 
 lates its corrosive nature. Note that uncoated specimen is most affected. 
 
376 Exposure Tests 
 TE 
 TABLE 50 
 
 THIS GROUP WAS IN SALT WATER FROM MAY 19 TO AUG. 19. 
 
 Ses innnevunir tres cn smc ents 
 Pipe 
 
 Section Inspection Report 
 No. 
 
 nnn earn enema 
 
 N-1 Very badly pitted and corroded at water 
 junction. Most severe corrosion on 
 exterior surface. Zine gone from sub- 
 merged section. 
 
 B-1 Same as N-l. 
 
 N-2 Very slight rust at a few small spots on 
 
 Black Asphaltum—Tung exterior. Inside in excellent genera! 
 
 Oil Paint condition, 
 
 B-2. Same as N-2. 
 
 N-3 Several round rust spots developed at 
 water line junction and considerable 
 scaling. Metal, however, is in gen- 
 erally sound condition. Inside, some 
 
 Treatment 
 
 No Paint 
 
 Aluminum Coal Tar Bitu- failure of paint at water line junc 
 mastie Solution tion, but generally sound, excellent con- 
 dition. 
 
 B-3 Same as N-3, except slightly more rust 
 on exterior than on N-3. 
 
 a aN nee eh 
 N-4 Marked corrosion at water line. Other- 
 
 Black Pigmented Spar wise sound. Only moderate corrosion 
 Varnish on inside at water line junction. 
 B-4 Same as N-4. 
 
 aaa NNN TI Ties innccnr crc 
 
 N-5 A few slight corrosion spots at water 
 
 Aluminum Spar Varnish line. Otherwise sound. Same condi- 
 tion inside. 
 
 B-5 Same as N-5. 
 
 N-6 Sharply defined corrosion spots at water 
 
 Red Lead line junction. Slight corrosion on in- 
 side. Marked blistering. 
 
 B-6 Same as N-6. 
 
 N-7 A few comparatively slight corrosion 
 spots at water line. Considerable blis- 
 tering of paint. Otherwise sound. 
 
 Zine Chromate Practically no corrosion inside but much 
 blistering of paint. 
 
 B-7 Same as N-7 but conditions more pro- 
 nounced. 
 
 N-S Considerable corrosion at water line junc- 
 tion on exterior. Inside, moderate cor- 
 
 Zine Dust Primer rosion. Some blistering of film. 
 B-8 Same condition as N-8 but slightly more 
 pronounced. 
 
 N-9 Well defined corrosion on outside at water 
 
 line. Comparatively no corrosion on 
 
 1 Coat Red Lead and 1 inside. Considerable blistering of film. 
 
 Coat Aluminum Varnish B-9 Same conditions as N-9 but slightly more 
 pronounced corrosion. 
 
 N-10 Moderate corrosion on outside at water 
 line. Inside, corrosion and slight blis- 
 Iron Oxide Paint tering. 
 B-10 Same condition as N-10, possibly more 
 pronounced. 
 
 Ee, ee 
 
Exposure Tests S74 
 
 —— Sess 
 
 Testing Toxic Compositions to Prevent Fouling of Steel 
 Ships and to Preserve Wood Bottoms.—A resume of four 
 years’ research in tests of this character and which included 
 
 FIGURE 160 
 
 View of a very small section of test racks in Beaufort harbor. Members of 
 inspection committee pulling up panels and examining them. 
 
 FIGURE 161 
 
 Painting “patch” tests on destroyer. If good results are obtained 
 
 in panel tests, the composition may warrant a “patch” test on a 
 
 small craft before conducting a large size service test upon a 
 battleship. 
 
378 Exposure Tests 
 
 nearly two thousand panels is given in Scientific Section Cir- 
 cular No, 259. Briefly stated, the test compositions were usu- 
 ally applied to steed panels 12” wide and 18” long, with a 
 large hole at the top, through which was placed a ‘‘sister 
 hook’? and a rope for suspension. ‘Two holes were made at 
 the bottom corners, through which to place wires to suspend 
 bricks to act as weights to keep the panels from swaying in 
 the water during rough periods. These panels were generally 
 submerged to such depths that at ebb tide the surfaces would 
 be about two feet below the surface of the water. The type 
 of racks from which the panels were suspended is shown in 
 Fig. 160. In general, the start of such tests should be made 
 early in the spring when the barnacles are just starting to 
 run. If the panels are exposed late in the fall, no erowths 
 may be obtained in many waters, and the only results indicated 
 will be the effect of the salt water upon the coatings and the 
 underlying metal surfaces. An exposure of two months in 
 June and July in many waters will produce growths which 
 could not be developed during the other ten months of the 
 year. In making tests of this. character, it is well to select 
 exposure locations at widely separated points. ‘Thus in the 
 United States, exposure stations where our tests have been 
 made have ranged from Atlantic City, N. J., to Beaufort, N. C., 
 south to Key West, Fla., on the Atlantic, west to Los Angeles, 
 and north to Puget Sound on the Pacific. A chart such as was 
 used by the writer for reporting results is given below: 
 
 SPECIMEN REPORT 
 SHIP BOTTOM PAINT TESTS 
 
 Number of test plate, C-3. Formula of 
 
 Submerged at Beaufort, N. C. composition 
 
 Date submerged, 8/1/22. 
 
 Weight of liquid paint applied to 2 coats A, C. No, 14. 
 standard panel 12/18”: 1st coat, 18 grams | 1 coat A. F. No. 2. 
 
 2d coat, 19 grams | Formula No. 576. 
 3d coat, 27 grams | Shellac Paints. 
 
 INSPECTION REPORT 
 
 Date, Nov. 17, 1922 >) Date. comes 1atesscucees Dates nae 
 
 HispeClotinsc. ecu Inspectori....: Inspectot...... Inspectot...... 
 
 Foulitigs< a6 2a Slight, «fs etaduhaecsbecerneenenie anni seen tec ea 
 COTTOSIOTE <.ke. Slight, «= - |  _ Pikcaaseosentoneree nt gel ahha a a 
 Film condition..| Fair, © _ Pasevecvecyneeteepy cnc ligating en 
 Remarks: Light slime, few bar- | Lost, © JoecbecteccceneesssPesseseuspeseeanesn senna 
 
 nacles, rust spots, 
 A. F. off few spots, 
 soft, washes easily. 
 
 ane, Nn aes NN tele eee ar Sent nove en Dare ne 
 
Exposure Tests 379 
 
 Conditions to report on fouling and corrosion: None 
 
 Cee Shght 
 Moderate 
 Cons.derable 
 Heavy 
 
 On film condition: Excellent 
 Good 
 Fair 
 Poor 
 
 Bad 
 
 ‘BEAUFORT. N.C. MAR. 1923 
 
 FIGURE 162 
 
 478—Rosin-rubber compound. 484—Rosin-rubber 
 
 compound containing arsenic, copper, and mercury 
 
 toxics and Titanox and zine oxide exposed one 
 
 year. 442—Rubber latex coating exposed four 
 
 months. 475—Hot plastic green soap compound 
 exposed one year 
 
380 Exposure Tests 
 
 Testing Copper Paints.—In determining the toxic value of 
 copper paints to be used as preservatives for wooden ships 
 and for wooden piling, slats 34" thick, 12 feet long and 3” 
 wide, may be selected. The wood may be given two coats of 
 the toxic preparation, and be submerged so that one-half of 
 
 FIGURE 163 
 
 First series of teredo test panels after exposure. 
 
 the panel is exposed to the air. By this type of exposure, 
 very Severe results may be obtained at the water line. After 
 exposure for a few months, the panels may be removed and 
 sawed in sections to determine whether teredo or limnoria 
 have been admitted. 
 
 aM 
 
Exposure Tests 381 
 
 FIGURE 164 
 
 Cross-sections of first series of teredo panels after test. 
 
 Testing Protective Coatings Upon Aluminum Alloy Sur- 
 faces—In Figures 165 and 166 are shown a few of the test 
 racks exposed by the writer at Washington, D. C., and at 
 Hampton Roads, Va., for determining the durability of vari- 
 ous protective coatings upon steel and upon aluminum and 
 magnesium alloys. It will be noted that the panels, which 
 are 6 x 12 in size and approximately 18 gauge, were placed in 
 wooden racks with wooden flanges at top and bottom to pre- 
 vent any contact with other metals. In the Hampton Roads 
 exposure, the panels were tied to metal I-beams and exposed 
 at an angle of 45° to the vertical, approximately six feet above 
 flood tide. It was thought that this exposure would be an 
 extremely severe one on account of the salt spray dashed 
 against the panels in rough weather. The results on some 
 of these panels are indicated in the photographs. It was 
 found that while as a rule paints which give adequate pro- 
 tection to steel surfaces are also useful upon aluminum and 
 other light alloys, the coatings to use on the latter metals 
 should be extremely elastic. Coatings made with nitrocellu- 
 
382 Exposure Tests 
 
 lose lacquers (applied directly to the metal) or with varnishes 
 do not withstand the tremendous stresses set up by the expan- 
 sion and contraction of these alloys, whereas linseed oil coat- 
 ings have proved entirely watiaranioue 
 
 It will be noted in these tests that there were included a 
 series of tensile strength specimens upon which physical tests 
 had been made previous to exposure. These specimens can 
 be removed from the rack every three months and the tensile 
 strength and elongation again determined. It is considered 
 that such a method of test is an important one where light 
 
 FIGURE 165 
 
 Exposure tests on coated duralumin panels over surface of ocean at Hampton 
 Roads, Va. 
 
 alloys are coneerned, as it has been indicated that exposure 
 to salt water, while not apparently affecting the surface at 
 first, may cause intererystalline embrittlement of a very seri- 
 ous nature. Such embrittlement is not usually indicated by 
 the surface appearance of the specimens. Photomicrographie 
 examination and. X-ray tests are important where” a Com pIER 
 study of the subject is considered. 
 
383 
 
 Exposure Tests 
 
 ‘UOJSUIYSVAA JB S80} JOOr poiedofaoV AOT[V wUNUTUIN]B IOJ YowVs 4sSay, 
 
 QOT TINO 
 
384 Exposure Tests 
 
 SOA OG SOE A I NG: AION: Na 8 A IT 
 
 ' 
 ; 
 E 
 
 FIGURE 167 
 Panels from Washington tests. 
 
 16 Steel—Aluminum Paint A. Very good. 
 
 17 Steel—Aluminum Paint B. Considerable rust. 
 
 18 Steel Aluminum Paint C—Very heavy alligatoring and dark 
 surface. 
 
 23 Duralumin—Coal Tar Varnish Paint. Very heavy scaling. 
 
 23 Steel—Coal Tar Varnish Paint. Sound. This indicates the fact 
 that varnish paints upon steel may be durable, but when ap- 
 plied to duralumin they rapidly flake off. 
 
 BD 18 Duralumin—<Aluminum Paint C. Heavy alligatoring. Dark. 
 
Exposure Tests 385 
 
 FIGURE 168 
 
 Panels from Washington tests. 
 
 19 Duralumin. Red Lead Primer. Excellent. 
 
 20 Duralumin. Zine Chromate Primer. Excellent. 
 21 Duralumin. Zine Dust Primer. Excellent. 
 
 22 Duralumin. Titanox-Zine Primer. Excellent. 
 
 All these four paints, made with linseed oil, have given excellent 
 adherence and show no flaking. 
 
 5 Duralumin. Green Nitro-Lacquer. Dull; good except for tiny 
 scales. 
 7 Duralumin. Black Asphaltum Varnish. Scaled; rusty. 
 9 Duralumin. Air Drying Japan. Checking; dull. Some rust. 
 23 Duralumin. Coal Tar Varnish Paint. Heavy scaling. 
 These latter four panels, being coated with more brittle paints, 
 
 have not shown the adherence that was given by the linseed oil 
 paints. 
 
er 
 
 386 Exposure Tests | 
 Dennen aes, 
 TENSILE PROPERTIES OF PANELS TESTED. 
 
 Tensile Properties 
 Ultimate Tensile Strength Hlongation (2”) 
 
 Specimen No. lbs. sq. in. per cent 
 
 A l 61,880 22.5 
 
 A:2 61,670 22.0 
 
 As 60,420 a 
 
 A 4 60.620 25 
 
 BJ 58.160 20.5 
 
 pe 58.160 22.0 
 
 B 3 59,740 ; 21.5 : n 
 STEEL 
 
 Ald 60,000 19.0 
 
 Pee 65,710 175 
 
 ae 50,430 30.5 
 
 $62 51,280 31.5 
 
 A—Danels from ‘Aircraft Factory. 
 B—Tlanels from Bellevue Laboratory. 
 
 Testing Nitrocellulose Lacquers on Metal.—The largest use 
 for nitrocellulose lacquers at the present time is upon the 
 
 FIGURE 169 
 
 Roof tests of lacquers and varnishes on writer’s laboratory, showing panels 
 45° to the vertical, which nearly doubles the speed of disintegration. Also note 
 apparatus for daily spraying panels with water, which also greatly increases 
 speed of failure, thus making such tests accelerated roof exposure tests. 
 
Exposure Tests 387 
 
 metal bodies of automobiles. It is usual, therefore, to employ 
 metal panels in testing these lacquers. Automobile fender 
 stock panels of any suitable size may be used. The lacquer 
 may be sprayed, flowed or spun upon the panel to the desired 
 thickness and the panel exposed on the type of rack shown in 
 Figure 169. 
 
 Since some lacquers do not adhere tenaciously to metal 
 without proper undercoats, it is the procedure in laboratories 
 of some lacquer plants to. have made up a large number of 
 panels primed and surfaced ready to receive the test lacquer. 
 The lacquer is then usually sprayed on under conditions 
 closely similating those which obtain in actual shop practice 
 where automobiles are finished. Usually, the first defects 
 noted on lacquer exposures are chalking, which sometimes 
 obseures the color. Small portions of the panels may be 
 rubbed from time to time to remove the chalked surface and 
 to determine whether the film below is in good condition. 
 Observations should also be made to determine whether any 
 water ‘‘Spotting’’ is shown. Wherever these tests are made 
 there should be included control tests of a standard lacquer 
 of the desired color upon which to judge the value of the 
 sample under test. (See also chapter 36.) 
 
 Exterior Exposure of Lacquered Wood Panels.—In deter- 
 mining the durability of lacquers which have been proposed 
 for use upon exterior surfaces, it is generally advisable to 
 apply them not only to wooden panels which are unprimed, 
 but to panels which have been primed with moisture resisting 
 primers which will tend to seal up the surfaces and prevent 
 expansion and contraction due to moisture absorption or 
 elimination. It is also advisable to apply the lacquers to 
 wickerware panels such as are used in the construction of 
 porch furniture. Lacquers which may prove useful upon cer- 
 tain types of surfaces often scale off wickerware because of 
 the great changes in volume of the wicker during moist peri- 
 ods. The comparative value of special elastic sealers and 
 primers for wickerware may be indicated by such tests. Pan- 
 els of this type are shown in Fig. 170. 
 
 Testing Paints for Cement Surfaces ‘by an Accelerated 
 Method.—In order to determine in a short period of time the 
 relative resistance of paints to the effects of the strongly al- 
 kaline surfaces of damp, freshly laid cement and plaster, a 
 
388 Exposure Tests 
 
 ; aN 
 
 (iy {iil 
 
 FIGuRE 170 
 Testing Lacquers on Wicker Panels. 
 
 test was designed of a most severe character. It is probably 
 several times as severe as the conditions that would obtain in 
 actual practice, and therefore may not be termed a normal 
 test. Apparently, however, it gives considerable informa- 
 
Exposure Tests 389 
 
 tion regarding the efficiency of various priming liquids and 
 subsequently appled paint coatings. ~The tests are fully de- 
 seribed below, .and.the results are charted in detail. The. 
 tests were made with painted panels of both Portland cement 
 and plaster. 
 
 Making Panels.—The cement panels were made with one 
 part Portland cement mixed with two parts of dry sand and 
 the usual amount of water. The mixture was poured into 
 cake tins approximately 12 x 9, to a depth of 114 inches. The 
 tins contained sheets of chicken wire the size of the pan to 
 act as reinforcing. After setting for six days, the panels 
 were removed from the tins. 
 
 In making the plaster panels, the procedure was to first 
 make up cement panels one inch thick of the Portland cement 
 sand mixture reinforced with wire. During the drying period, 
 the top surface of each was scratched so that good bona’ 
 ing properties with the white finish coat could be obtained. 
 The white coat was made with ‘‘lime putty’’ prepared by add- 
 ing water to hydrate of lime tg produce a paste of medium 
 consistency and allowing it to stand over night. To 2 parts 
 by volume of this lime putty there was added one part of 
 gypsum gauging plaster (hard wall gypsum plaster). This 
 was applied to the base panels to a thickness of about 3/8”. 
 The making of all panels was done at the laboratory by an 
 expert plasterer who had spent about twenty years in the 
 trade. 
 
 Priming and Painting Panels—After the manufacture of 
 the panels, they were allowed to dry under normal conditions 
 for a period of two weeks. The primers (Nos. 2 to 16) were 
 then applied in one coat work. After allowing the primers 
 one week for drying, the paints (A to H) were applied, in two 
 coat work, allowing a period of one week between the drying 
 of each coat. A strip about one inch wide at the top of each 
 panel was then coated with chrome green paint which is 
 rapidly bleached out when in contact with lime compounds 
 from cement. The panels were then stencilled with designat- 
 ing numbers, dried the usual period and placed in a series 
 of pans made of galvanized iron, 126” long, 26” wide, and 1%” 
 deep. Hight pans were required to hold the total of 256 
 panels in the test. After placing the panels in the pans, 
 
390 Exposure Tests 
 
 sufficient water was added to each pan so that the water 
 would come up to about two-thirds the height of the panels. 
 
 FIGURE 171 
 View showing plasterer and assistants preparing plaster panels for the paint tests. 
 
 Heat, Cold and Absorption Tests on Painted Cement.— 
 The results of tests such as are outlined above, upon many 
 paint compositions, 1s given in Scientific Section Cireular No. 
 299. In general this test is extremely severe and causes the 
 type of failures shown in the illustrations. Other tests may 
 
Exposure Tests 391 
 
 be employed, such as a test to determine the water resistance 
 of the primed surface. In a test of this sort, the writer has 
 used small circular pans filled with the same type of plaster 
 described above. Pans about 3” in diameter and %%" deep 
 are employed. After ;priming, four days are allowed for 
 drying. Upon the surface of each is placed 2 cc. of water 
 
 FIGURE 172 
 SUPER-ACCELERATED ALKALI-WATER TESTS 
 
 View of basement laboratory floor with 8 long pans filled with 255 painted 
 
 panels semi-submerged in water. Dark spots on some panels indicate water 
 
 that has come through panel affecting the oil and bringing the saponified 
 yellow product to the surface. 
 
 and a watch glass placed over the water to prevent evapora- 
 tion. If the water is absorbed, an additional quantity is 
 added. After a period of three hours, the excess moisture is 
 wiped off and the panels re-weighed. The increase in weight 
 is the water absorbed, which is then calculated in per cent, 
 
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 do} je Usels owory YIM podiajs usy pur pejuted st Jourd Jajsvjd 10 JuewIed Jo apis doy, 
 
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 GLT aanory 
 
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 yea iA J) “ne, 
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 (PERS ; ; 
 
 ride 74 Gul Wx 
 
 Exposure Tests 
 
 . . 
 ee. 8.5 3.4 
 
 392 
 
393 
 
 Exposure Tests 
 
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 ‘SLSG], ULV M-VIVMIV GALVYATIOOV-aadNG 
 FLL aiooLy 
 
 In the table 
 
 ratory are indicated 
 
 ight of the plaster panels 
 
 based upon the we 
 
 labo 
 
 The writer has also conducted tests w 
 
 referred to on page 
 
 ined in this 
 
 . 
 
 obta 
 
 below, some results 
 
 anels such as are 
 
 th p 
 
 1 
 
 der 
 
 ated rooms upon the 
 
 iin Or 
 
 r and eold a 
 he 
 
 in moist al 
 isture in 
 
 389, 
 
 to determine the effect of mo 
 
 ced) 
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 394 Exposure Tests 
 
 ished with white lacquer coat- 
 
 Plaster panels primed with No. 11 or No. 13 Primer and fin 
 
 the panels, they are immediately placed in a large cabinet, 
 cooled to a temperature of 40° F. by an ice making equip- 
 ment, or placed in a chamber saturated with water vapor and 
 heated to the desired degree. 
 
 Testing the Durability of Airplane Doping Systems.—One 
 of the requisites for a doping system is lowness in weight. 
 Since standard cotton airplane cloth weighs about 4% oz. per 
 sq. yd., it is desirable that the total doping system should not 
 
 wv 
 ce 
 om 
 i? A] 
 g 
 R ) 
 cee 
 & 
 ‘J ; 
 5 Ube 
 ~~ ~ 
 | n 
 = = 
 ye 
 1» = 3 
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 ee 
 bm 8 
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 = 
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Exposure Tests 395 
 
 — Ela, 
 
 % Water 
 
 No. Primer Absorbed 
 ee Ste cis cain oes vinlel ore Ge vie oe e's oa towels eens ae 54.0 
 SINCE ES 2 Bap 
 8 Magnesium Fluosilicate H-T Solution ..........-e-e eevee, 45.0 
 Peeters TOU woaiuim Silicate (20° Be.) 200 .....ccecccesesves 21 
 5 Cold Water Paint—Glue Base Type .............ceevcceeves 54.6 
 Peeiiesdipnate (2 1bs, per gal. of water) ........ceenesceeons 48.9 
 7 Tung Oil White Flat Wall Paint, not thinned..........%... 0.1 
 8 Tung Oil White Flat Wall Paint plus 1 pint Raw Tung Oil per 
 
 eM aieic ly cae elas ee a he ee bs ers eee ew ee a 
 
 9 Tung Oil—Ester Gum Spar Varnish 100, Mineral Spirits 25.. 0.0 
 
 Mumm Mineral Spirits GO . 0... cece ce emer eect ena neees 16.3 
 
 MIM VATUICN LAQUIC .. 1. se eee ct eee re eee tweet esac wenns 0.1 
 
 12 Lead Linoleate 15, Zinc Linoleate 15, Toluol 70 ........... pie 
 
 Pee erminiiny ptearace 15, Turpentine 70 .........02.0ececceee Oct 
 
 EE Oy ee gab rev ols sie ease ows won ore eae 1338 
 
 Benen SOlltion OU, Rosin 50 20... cece eves e ee sere sewcenees 0.0 
 
 16 32 oz. Cotton Solution 100, Ester Gum 50, Toluol 70, Lindol 10 = 1.0 
 
 add more than 3% oz. per sq. yd., making a total of approxi- 
 mately 8 oz. The addition of an ounce per sq. yd. to a fabric, 
 through the protective coating system, may add tremendously 
 to the weight carried by a plane, due to the very large yardage 
 used. Lower speed and greater fuel consumption might re- 
 sult from such added weight. Another requisite is tautening 
 power. Tautening is probably developed by the shrinkage of 
 the cellulose compound as it emerges from solution in the 
 solvent. The type, character, and amount of solvent used in 
 dopes has a very pronounced influence upon the degree of 
 tautness developed. The grade of cellulose compound used 
 is also of importance. For instance, in nitrate dopes the type 
 usually applied is ‘‘dope’’ cotton, and the degree of nitration 
 is such that the viscosity is very high; a solution containing 
 as much as eight ounces of nitrocellulose per gallon being 
 quite viscous. The tensile strength of the doped fabric is 
 also a matter of great importance; the application of the dope 
 usually increasing the tensile strength to a very marked ex- 
 tent. If, however, the dope breaks up during exposure to 
 sunlight and develops free acid compounds,, the cloth is 
 
 attacked, and very rapid lowering of strength is observed. It 
 should be borne in mind, however, that the usual period dur- 
 ing which a plane is flown is 200 hours. After that period it 
 is customary to rip all the fabric off the wings to examine the 
 structural parts for any signs of weakening. For this reason, 
 doping systems that will last 200 flying hours with satistac- 
 tory results under conditions of high humidity, temperature 
 
 and sunlight, are usually considered satisfactory. 
 
396 Exposure Tests 
 
 FIGURE 176 
 
 Underside of doped fabric first coated with a gelatine tautener. 
 After exposure very rapid fungus growth was observed. 
 
 For testing the comparative effectiveness of airplane dopes, 
 the writer uses fifteen inch square frames made of one inch 
 dressed white pine joined together at the corners. To these 
 
Exposure Tests 397 
 
 open frames are attached, under fairly definite tension, stand- 
 ard cotton airplane cloth such as is used by the Navy Depart- 
 ment on all seaplanes. After the fabric is tacked in place, 
 the dope is applied aecording to the desired schedule. Panels 
 are then placed upon a test rack at an angle of 45 degrees to 
 the vertical, facing south, and, if possible, sprayed daily with 
 water for a period of one hour. Very rapid results are ob- 
 tained. In a period of three months much information can 
 be secured regarding the serviceability of various doping 
 schemes. At the end of that period of time, the frames are 
 removed to the laboratory and tested for tautness with the 
 finger, or with an apparatus which records tautness in numeri- 
 eal values. Strips of fabric can them be removed from the 
 frame and tested for tensile strength and elongation in order 
 to determine whether any loss has taken place due to the 
 deterioriation of the dopes or due to the effects of ultraviolet 
 light which may have penetrated through the dope films. 
 There are given below the results on a few out of several 
 hundred tests which have been conducted by the writer at the 
 Pensacola Naval Air Station and other points. 
 
 2 
 
398 Exposure Tests 
 
 FIGURE 177 
 
 Both applied on airplane fabric previously doped with 4 coats of clear nitrate 
 dope. After weathering 4 months the surfaces were subjected to thumb pres- 
 sure. Note concentric ring cracks on surfaces where clear varnish was used, 
 allowing embrittling effect of sunlight. Surface on left protected with pig- 
 mented spar varnish is still distensible and shows no effects of pressure. 
 Pigmentation shuts out active rays of sunlight. 
 
 CLEAR SPAR VARNISH 
 
 PIGMENTED SPAR VARNISH 
 
 aioe 
 
399 
 
 Exposure Tests 
 
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CHAPTER XXIII 
 
 ANALYSIS OF PAINT OILS 
 
 Some of the material relating to this subject, which ap- 
 peared in previous editions of this volume, was used as the 
 basis of methods adopted in specifications of the A. 8. 'T. M. 
 which appear below. The specification for linseed oil is first 
 presented. Additional matter in connection with the deter- 
 mination of foots, unsaponifiable matter, and the hexabromide 
 number of oil, is then included. Oils other than linseed oil 
 in general may be analyzed by following these methods. Data 
 is also presented in Table 51 relating to the constants of many 
 oils examined at this laboratory. Following the matter on 
 linseed oil there is presented the A. 8. T. M. specifications for 
 -raw tung oil, for perilla oil, and for soya bean oil, with some 
 additional notes relating to tests which are not included in 
 the specifications. 
 
 TABLE 51.-—Constants of Oils Examined in Writer’s Laboratory. 
 
 i o 7 A 
 = ; q i = 
 S 
 Oil. Species. & 5 | 8 re ee 
 Se Be Be Boe 
 SOO] 28 | Ge) 2) Be 
 Sighe| sa | 82] 3 | 8a 
 Peis. sites < | 
 ie een Salvia. cuk«-. 934 | 196.3| 192.2) .6 | 1.4885 | ~ 
 Hispanica > 
 ee re 8 ae 921 | 125. | 190.1] 4.1 | 1.4800| & 
 Mays S 
 Cottonseed....... Gossipium...... .924 | 111.7) 194.3) .9 | 1.4720 es! 
 Herbaceum & 
 Hempseed....... Cannabis....... .927 | 149.4) 191.1) 3.9 | 1.4822 = 
 Sativa ee 
 Paoomceed......| Eriodendron....| .924 | 119. | 196. |.....}........ a 
 Anfractuosum > 
 Linseed (Boiled)..| Linum......... GATE TIO TR 7all aeio) | 48907) oe 
 . Usitatissimum ~) 
 Linseed (Heavy | Linum......... .968 | 183. | 189. | 2.8 | 1.4966 TA 
 Bodied Usitatissimum 2 
 Linseed (Lithogra-| Linum......... .970 | 102. | 199. | 2.7 | 1.4978 s 
 graphic). Usitatissimum 
 Linseed (Raw)...| Linum......... 934 | 186. | 191. | 2.0 | 1.4800} & 
 Usitatissimum CF 
 RCIA i wc let oxen Conepia.....<.-- SOGU nial OO co Aly et il, eaneta ce a 
 Grandifolia 
 
 Palo Maria...... Calophvllum....| .934 | 96.5! 193. [46.1 | 1.4743 
 
402 
 
 Analysis of Paint Oils 
 
 TasLeE 51—Cont.—-Constants of Oils Eramined in Writer's Laboratory. 
 
 & 
 = 
 Fi 
 Oil. Species. = 
 goo 
 paid 1D LAD 
 Thy 
 Inophyllum 
 Porline-35.o 568 Perla cis eres 934 
 Ocimoides 
 Poppyseed....... Papaver:2 ou: a ah Gee 
 Somniterrum 
 Raisinseed (Grape-|s a en ee .926 
 seed). 
 THOSINUO: 6 oe Pinne i feo .964 
 Palustris 
 Rubberseed...... Hevea ss 33a .924 
 Brasiliensis 
 Sésame ss 5.0 ; Sesamum....... .924 
 Orientale & In- 
 dicum 
 Soya Bean....... Sols ce eee 924 
 Hispida 
 Sunflower...... Helianthus. .... 924 
 Annus 
 Lumbane 72-3, Aleurites....... 927 
 (Candlenut). Moluccana 
 Lumbang (Soft). .| Aleurites....... .938 
 Trisperma 
 Peanitice cae Arathia.\i25,.) eee 
 Hypogaea 
 Tung (American) .| Aleurites....... .941 
 Fordii 
 Tung (Chinese)...} Aleurites....... .944 
 Fordii 
 Walnkt sie fey Juglans te .926 
 Regia 
 Wood (Japanese) .| Aleurites....... 934 
 Cordata 
 Channel Catfish.) 32 eee .923 
 Fura roe ed Go Phota. ees 925 
 Vitulina Ete. 
 Grayfigh, 05 12) ee aoe ee .916 
 Menhaden....... Alosa Menhaden | .932 
 (Brevoortia Tyr- 
 ranis) 
 Salmon: oie a DANG OC eno 927 
 Salar 
 Sardine.:.:. 2s... )sOlipean us ee .919 
 Sardinus 
 Shark. . 4 sk ee ee .910 
 Shark Liver...... Boréalig.3 5, oe .922 
 Scymnus 
 Skate Liver...... Squatina....... . 932 
 Vulvaris 
 Diana Bish 25% 2} are ee ae 933 
 Whale vere G. Baloena..... 924 
 Yellow Tailfish...| Seriola......... .932 
 
 Dorsalis 
 
 Iodine Number 
 
 (Hanus) 
 
 129. 
 
 102.2 
 166.0 
 165.0 
 
 164.2) 194.0) 4.4 
 
 fe 
 BS | 5 
 
 ms 5 
 =a ee 
 
 a2 | 2 
 
 ia] oO 
 
 nn <x 
 
 188. | 2.0 
 1923-150 eee 
 193. | 4.5 
 35.5 |32.4 
 193.2 Jo730 
 190. | 1.4 
 189. 32:3 
 
 193.0) 2.2 
 192-615 s.2 
 192.0} 4.8 
 
 183.0} 9.8 
 177 .3)10.4 
 
 158.9} 5.2 
 62.2) 1.3 
 
 179.9) 1.8 
 
 a TAV LADAA) 
 
 (STIO CHAS ANV 
 
 ——— 
 
 | 
 
 (STIO LAN) 
 
 (‘STIO IVWINV ANIYVN) 
 
Analysis of Paint Oils 403 
 es  " 
 
 A. 8S. T. M. TENTATIVE SPECIFICATIONS FOR RAW 
 LINSEED OIL 
 
 I. PROPERTIES AND TESTS 
 
 1. Linseed oil shall be the pure oil pressed from flaxseed and shall con- 
 
 form to the following requirements: 
 Maximum Minimum 
 
 Specific Gravity 15.5° /15.5° C..... eee eee eee ees 0.935 0.931 
 MSIL cbc c cc co tee ce ences eee ce we 4.0 Paar 
 Saponification Number............cesseeeceeces 195.0 189.0 
 Unsaponifiable Matter, per cent................- 1.50 Lectees 
 MUN TEE CVV IIS) % 0. occ ee ce ce ee ae 180.0 
 
 Loss on Heating at 105-110° C., per cent......... 0.2 
 
 0 SE re Not darker than a freshly prepared solution of 
 
 1.0 g. potassium bichromate in 100 cc. pure 
 concentrated sulfuric acid (sp. gr. 1.84). 
 Foots, per cent: 
 IRE eas c)e ss aly els sees se ee ewe ees 1.0 
 IPRUIMN Rece cows kee ko e's, 6 s'en0 a's vie tee nesses 4.0 
 
 II. METHODS OF TESTING 
 
 2 The oil should be tested in accordance with the following methods: 
 
 General.—All tests shall be made on oil which has been thoroughly agi- 
 tated before the removal of a portion for analysis. 
 
 Specific Gravity—Use a pyknometer, accurately standardized and having 
 a capacity of at least 25 ce., or any other equally accurate method, making 
 the test at 15.5° C. water being 1.000 at 15.5° C? 
 
 Acid Number—Weigh from 5 to 10 g. of the oil. Transfer to a 3800-ce. 
 Erlenmeyer flask. Add 50 cc. of a mixture of equal parts by volume of 95- 
 per-cent ethyl alcohol and c.p. reagent benzol. (This mixture should be 
 previously titrated to a very faint pink with dilute alkali solution, using 
 phenolphthalein as an indicator.) Add phenolphthalein indicator and titrate 
 at once to a faint permanent pink color with 0.2 N sodium hydroxide solution. 
 Caleulate the acid number (milligrams KOH per gram of oil). 
 
 Saponification Number.—Weigh about.2 g. of the oil in a 300-cc. Erlenmeyer 
 flask. Add 25 ce. of alcoholic sodium hydroxide or potassium hydroxide solu- 
 tion. Put a condenser loop inside the neck of the flask and heat on the steam 
 bath for one hour. Cool, add phenolphthalein as indicator, and titrate with 
 0.5 N H,SO,4. Run two blanks with the alcoholic sodium hydroxide solution 
 These should check within 0.1 cc. 0.5 N H,SO4. From the difference between 
 the number of cubic centimeters of 0.5 N H,SO,4 required for the blank and 
 for the determination, calculate the saponification number (milligrams KOH 
 required for 1 g. of the oil). 
 
 Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-cc. 
 long-neck flask. Add 5 cc. of a strong solution of sodium hydroxide (equal 
 weights of NaOH and H,O) and 50 ce. of 95-per-cent ethyl alcohol. Put a con- 
 denser loop inside the neck of the flask and boil for two hours. Occasionally 
 agitate the flask to break up the liquid, but do not project the liquid onto 
 
 *Tf linseed oil of the high-iodine-number type is desired, the minimum 
 iodine number, as specified above, should be changed to 188.0. 
 
404 Analysis of Paint Oils ) 
 
 an nnnnnn enn ncn ncn nner nn nr reer renee SSS 
 the sides of the flask. At the end of two hours, remove the condenser and 
 allow the liquid to boil down to about 25 ec. 
 
 Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
 Dilute with water to 250 ce, add 100 cc. of redistilled ether. Stopper and 
 shake for one minute. Let stand until the two layers separate sharp and 
 clear. Draw all but one or two drops of the aqueous layer into a second 500- 
 ce. separatory funnel and repeat the process using 60 cc. of ether. After thor- 
 ough separation, draw off the aqueous solution into a 400-cc. beaker, then the 
 ether solution into the first separatory funnel, rinsing down with a little 
 water. Return the aqueous solution to the second separatory funnel and 
 shake out again with 60 cc. of ether in a similar manner, finally drawing the 
 aqueous solution into the beaker and rinsing the ether into the first separatory 
 funnel. 
 
 Shake the combined ether solution with the combined water rinsings and 
 let the layers separate sharp and clear. Draw off the water and add it to the 
 main aqueous solution. Shake the ether solution with two portions of water 
 (about 25 ec. each). Add these to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water down to 
 the stopcock and draw off until the ether solution just fills the bore of the 
 stopcock. Wipe out the stem of the separatory funnel with a bit of cotton on 
 a wire. Draw the ether solution (portionwise if necessary) into a 250-ce. 
 flask and distill off. While still hot drain the flask into a small weighed 
 beaker, rinsing with a little ether. Evaporate this ether, cool the beaker and 
 weigh. (The unsaponifiable oil from adulterated drying oils may be volatile 
 and aS a consequence may evaporate on long heating. Therefore, heat the 
 beaker on a warm plate, occasionally blowing out with a current of dry air. 
 Discontinue heating as soon as the odor of ether is gone. ) 
 
 Iodine Number.—Place a small quantity of the sample in a small weighing 
 burette or beaker. Weigh accurately. Transfer by dropping from 0.09 to 0.15 
 g. of oil to a 500-ce. bottle, having a well-ground glass stopper, or an Erlen- 
 meyer flask, having a specially flanged neck for the iodine tests. Reweigh 
 the burette or beaker and determine the amount of sample used. Add 10 ce. 
 of chloroform. Whirl the bottle to dissolve the sample. Add 10 cc. of 
 chloroform to each of two empty bottles like that used for the sample. Add 
 to each bottle 25 cc. of the Wijs solution and let stand with occasional shaking 
 for 1 hour in a dark place at a temperature of from 21 to 23° GC. Add 10 ce. of 
 the 15-per-cent potassium iodide solution and 100 ee. of water. Titrate with 0.1 
 N sodium thiosulfate, using starch as an indicator. The titrations on the two 
 blank tests should agree within 0.1 cc. From the difference between the aver- 
 age of the blank titrations and the titration on the samples and the iodine 
 value of the thiosulfate solution calculate the iodine number of the samples 
 tested. (Iodine number is given in centigrams of iodine to 1 g. of sample.) 
 
 Preparation of Wijs Iodine Monochloride Scolution.—Dissolve iodine in 
 glacial acetic acid that has a melting point of 14.7 to 15° C. and is free from 
 reducing impurities in the proportion so that 12 g. of iodine will be present in 
 1000 cc. of solution. The preparation of the iodine monochloride solution 
 presents no great difficulty, but it shall be done with care and accuracy in order 
 to obtain satisfactory results. There shall be in the solution no sensible excess 
 either of iodine or more particularly of chlorine over that required to form the 
 monochloride. This condition is most satisfactorily attained by dissolving in 
 
Analysis of Paint Oils 405. 
 eset 
 the whole of the acetic acid to be used the requisite quantity of iodine, using a 
 gentle heat to assist the solution, if it is found necessary. Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the remainder 
 until the halogen content of the solution is doubled. Ordinarily it will be 
 found that by passing the chlorine into the main part of the solution until 
 the characteristic color of free iodine has just been discharged, there will be a 
 slight excess of chlorine, which is corrected by the addition of the requisite 
 amount of the unchlorinated portion until all free chlorine has been destroyed. 
 A slight excess of iodine does little or no harm, but excess of chlorine must 
 be avoided. 
 
 Loss on Heating at 105 to 110° C_—Place 10 g. of the oil in an accurately 
 weighed 50-ce. Erlenmeyer flask and weigh. Heat in an oven at a tempera- 
 ture between 105 and 110° C. for 30 minutes, then cool and weigh. Calculate 
 the percentage loss. This determination shall be made in a current of carbon 
 dioxide gas. 
 
 Color.—Prepare a fresh solution of 1 g. pure potassium bichromate in 100 
 cc. of pure concentrated colorless sulfuric acid (sp. gr. 1.84). Place the oil 
 and colored concentrated solution in separate thin-walled clear-glass tubes 
 of the same diameter (1 to 2 cm.) to a depth of not less than 25 cm., and 
 compare the depths of color by looking transversely through the columns of 
 liquid by transmitted light. . : 
 
 Determination of Percentage Foots—Method.—With all materials at a 
 temperature between 20 and 27° C., mix, by shaking for exactly one minute 
 in a graduated tube, 25 cc. of the well-shaken sample of oil, 25 cc. of acetone 
 and 10 ce. of the acid calcium chloride solution. The tube shall then be 
 clamped in an upright position where settling can take place for 24 hours. 
 The temperature during this period should be between 20 and 27° Gs 
 
 The volume of the stratum lying between the clear calcium chloride solu- 
 tion and the clear acetone and oil mixture is read in 0.1 ce. or a fraction there- 
 of. This reading multiplied by four expresses the amount of foots present 
 as a percentage by volume. es 
 
 The tube referred to may be a burette or a color comparison tube. It 
 should have an internal diameter of 1.0 to 1.5 em., and a capacity of not less 
 than 70 ce. The graduations in 0.1 ce. should extend at least from 10 ee. to 50 
 ce. above the bottom of the tube. The acid calcium chloride solution is pre- 
 pared by saturating with calcium chloride a mixture of 90 parts water and 
 10 parts concentrated hydrochloric acid (sp. gr. 1.19). 
 
 Heated Oil Test.—Heat a portion of the oil to 65° Ce Noldzit- within 2° C. 
 of that temperature for 10 minutes; then cool it to room temperature (20 to 
 27° C.). Subject the sample promptly to the foots tests as described above. 
 
 Chilled Oil Test.—Heat a portion to 65° Gy. uold St within.-2° C. of that 
 temperature for 10 minutes; then place it in a dry, clean bottle, stopper tightly, 
 and place in a cracked ice and water mixture (0° C.) for exactly 2 hours. At 
 the end of this time, place the bottle for exactly 30 minutes in a water bath at 
 25° C., then subject promptly to the foots test, 
 
 Foots in Linseed Oil (Discussion).—Sub-Committee V on 
 Linseed Oil, of the American Society for Testing Materials, 
 during recent years has conducted a vast amount of work of a 
 
406 Analysis of Paint Oils 
 os 
 cooperative nature, especially in relation to the determination 
 of ‘‘foots’’ in linseed oil. Apparently the foots content of 
 oil consists of three elements, namely, (1) moisture, (2) high 
 melting point saturated fats which solidify at or below normal 
 temperature, and (3) mucilaginous material which is held in 
 the oil largely in suspension and in collodial solution. The 
 albuminous material referred to appears to be identical with 
 the substances forming the ‘‘break’’ when linseed oil is heated. 
 It has been found difficult to determine the percentage of 
 high melting point fats, since temperature and moisture con- 
 ditions affect to a very large degree the amount of these fats 
 which are detected by the various methods which have been 
 proposed. Among the methods proposed in the committee 
 work and reported on in 1924 are the following: 
 
 1. ‘‘Foots’”’ Test on thoroughly agitated sample as received 
 to be made by tentative A. S. T. M. method as described in 
 Specifications D 51 - 18 T. 
 
 2. ‘Boots’? Test on a portion, removed after thorough agi- 
 tation, heated to 150° F. (65.5° C.) for 10 minutes and allowed 
 to cool to room temperature (70 to 87° F.). 
 
 3. ‘‘Foots’’ Test on a portion, removed after thorough agi- 
 tation, chilled at 32° F. (0.0° C.) for 5 hours and allowed to 
 come to room temperature (70 to 80° F.). 
 
 4. ‘‘Foots’’ Test on a portion, chilled as in (3), heated at 
 150° F. (65.5° C.) for 10 minutes and allowed to cool to room 
 temperature. 
 
 The results given by some of these methods are presented 
 in Table 52. 
 
 TABLE 52 
 Foots, per cent Iodine Number 
 Chilled 
 Laboratory Foots,as Heated Chilled and Hanus Wijs 
 Received to150°F. to32°F. Heated 
 O1L No. 56 
 
 Nos. 1s) Bonneys a see eee 1.4 1.4 2.4 1.4 178.4 183.5 
 
 Nose.) Hull ce aie eeee 12 0.6 1.4 0.4 175.8 183.4 
 No. 3. (Bailey ent eer ee ye 6. 1.0 4.6 p Oar yf 183.62 
 
 Nowde Booves 25. eee 2.56 1.96 1.6 ue types! 182.5 
 
 Nowd. - Thompsons... wane 1.10 0.5 5 lr 1.0 177.8 182.7 
 
 NOs Gate aSlerccst asset ete aan 0.7 0.7 1.8 2.4 177.3 182.1 
 
 NO. Te SA Davibs os. 5 eee 1.0 0.4 1.2 0.8 178.5 181.3 
 NO@..8. > sStecleeaiceire comer ne 1.4 0.8 1.4 1.0 179.3 181.5 
 INO; 92) Croliwee. | ke ome crema 2.0 2.0 2.0 2.0 STARS See a aes 
 IN VOT AGE ite isos cncoeunensvees 1.48 1.67 1.6 1.6 176.64 182.57 
 Pita hie. ee eon ck eee 2.56 6. 2.4 4.6 179.3 183.62 
 
 Li Wicca Bee ee eee 0.7 0.4 ut 0.4 171.1 181.3 
 Difference: 23ers eee 1.86 5.6 1.4 4.2 8.2 2.32 
 Difference between High and 
 AANGTAROS ai che basco ee 1.08 4.43 0.8 3. 2.66 1.05 
 Difference between Low and 
 
 AV GVOIO Fa rhs ssa Ces ee 0.78 ale Le 0.6 1.2 5.54 1.27 
 
Analysis of Paint Oils 407 
 
 The method proposed by the committee for the determina- 
 tion of breaks or mucilaginous material in the oil was as fol- 
 lows: 
 
 Break Test—Twenty-five grams of the well-mixed oil are 
 weighed (accurately to 0.1 g.) into a 50-cc. Pyrex glass beaker. 
 Three drops of ¢. p. hydrochloric acid (sp. gr. 1.19) are added 
 and stirred thoroughly into the oil. The beaker is then placed 
 on a wire gauze, supported by a tripod, and heated with the 
 free flame of a Bunsen or Tirrill burner in such a way that the 
 rate of temperature increase will be from 125 to 150° F. (70 
 to 85° C.) per minute. A thermometer, suspended so that its 
 bulb is approximately in the center of the liquid, should be 
 used to register the temperature during the heating. If the 
 oil contains break, the evolution of bubbles attendant upon the 
 removal of the air and moisture usually ceases at the moment 
 of the formation of the break, which will rapidly cover the 
 bottom of the beaker with a gelatinous mass honeycombed 
 with bubbles of air. When the break formation has completely 
 covered the bottom of the beaker, it should be gently dis- 
 lodged with the thermometer or a glass rod but under no cir- 
 cumstances should the oil be agitated in any way prior to the 
 break. When the temperature has reached 550° F. (288° C.) 
 heating is discontinued and the oil allowed to cool to room 
 temperature. The cooled oil and break are now transferred 
 to a 250-cc. Erlenmeyer flask and the beaker thoroughly washed 
 with five successive portions (of 25 ec. each) of ¢ p. carbon 
 tetrachloride. These washings are added to the flask contain- 
 ing the oil and break. <A small glass rod should be used to 
 loosen any particles of break adhering to the sides or bottom 
 of the beaker. The flask is now tightly stoppered and thor- 
 oughly shaken for two minutes in order to completely extract 
 any oil which may have been included in the break. The di- 
 luted oil and break are then filtered on a Buchner funnel 
 through filter paper previously dried to constant weight at 
 220° F. (105° C.) and weighed accurately to 0.001 g. (What- 
 man filter paper No. 4 will be found capable of giving satis- 
 factory results for this purpose, although any similar paper 
 capable of giving rapid and perfect filtration of gelatinous 
 precipitates will also suffice.) Suction should be used in all 
 cases to facilitate filtration. The break retained on the paper 
 is washed with 50 ec. of carbon tetrachloride, which has pre- 
 viously been used to wash out the Erlenmeyer flask, and with 
 three 25-ce. portions of pure solvent. Each portion should be 
 allowed to run almost completely through the paper before 
 the addition of the next. The paper and break are finally 
 
408 Analysis of Paint Oils 
 haan NT ENE 
 
 dried for 30 minutes at 220° F. (105° C.), placed in a glass 
 weighing bottle which is tightly stoppered, allowed to attain 
 room temperature and weighed accurately to 0.001 g. The 
 increase in weight of the filter paper multiplied by 4 gives the 
 percentage of break (by weight) directly. 
 
 During the year 1926, further work was conducted. The 
 methods outlined for this work are presented below. 
 
 1. Foots test according to method described in the A. 8. T. 
 M. Tentative Specification for Foots Permissible in Properly 
 Clarified Linseed Oil (D 51 - 18 T). 
 
 2. Heat a portion of the oil to 65° C., hold it at that tem- 
 perature for 10 minutes, allow to cool to room temperature 
 and subject it to the foots test by the above method. | 
 
 3. Ash Test—Ignite and weigh to an accuracy of 0.001 g., 
 a porcelain crucible or small evaporating dish, having a capa- 
 city of about 50 ec. Into this container, weigh about 25 g. 
 of linseed oil. Add 3 drops of concentrated sulfuric acid. 
 Heat the oil over a gas burner carefully to the fire point, ignite 
 the oil, remove the burner and allow the oil to burn quietly 
 as long as possible. Proceed carefully in this way, avoid- 
 ing foaming and renewing heat only when the oil ceases to 
 burn. When all foaming has ceased, apply the full flame of 
 the burner until all the carbon has been burned and the ash is 
 uncontaminated by black particles. Cool the dish in a desic- 
 eator, weigh to an accuracy of 0.001 g., calculate the increase 
 in weight as percentage of ash present in the oil. 
 
 Some of the results obtained by the committee are presented 
 below: 
 
 TABLE 53 
 “‘Foots’ and Ash Determinations Made on Three Samples of Linseed Oil 
 Foots Test, Oil Heated Foots Test, Oil at Room ee 
 to 65° C. Temperature Ash Determinations 
 Observer 
 
 Sample Sample Sample Sample Sample Sample Sample Sample Sample 
 
 No. 60 No. 61 No. 62 No. 60 No. 61 No. 62 No. 60 No. 61 No. 62 
 INOS Lee ee ee 0.4 0.8 2.8 0.6 1.8 5a 0.093 0.085 0.160 
 Nop escheat ene 0.2 0.8 BIL. 0.8 2.0 ALO ine 0.100 0.140 
 No. 38.... 0.8 1.0 3.2 1.0 1,2 4.8 0.083 0.095 9.158 
 NOSE Sas hese oie 0.33 0.93 4.0 0.8 1.4 5.2 0.089 0.107 0.129 
 NG5. ee ee 4 0.6 3.2 1 1.4 6.4 0.093 0.004 0.135 
 NGs6a3 oo es 0.0 0.8 2.4 al74 2.0 6.4 0.119 (0.144) 0.131 
 INGitiiee eee 0.3 1.0 3.6 0.4 1.2 3.6 0.082 0.068 0.086 
 INOS Sohne eee 0.4 0.4 (9.2) 1.6 1.8 9.2 0.110 0.114 0.149 
 ING 3052 ieee eee Le 2 4.3 1.6 2.4 5.6 0.091 0.102 0.109 
 INO, JOR eee 0.0 (0.0) (0.0) 1.6 1.6 6.0 0.120 0.100 0.120 
 A Verages cor s4) cic 0.40 0.83 3.34 pi tea 5.6 0.097 0.096 0.132 
 Maximumn................ 1 Bis 1.2 4.3 1.6 2.4 9.2 0.120 0.114 0.160 
 Minimum................ 0.0 0.4 Ae 0.4 1.2 3.6 0.082 0.068 0.086 
 Deviation above 
 
 mean, per cent 200 44 29 A5 Al 64 24 19 21 
 
 Deviation below 
 mean, per cent.... 100 52 28 64 29 36 15 29 35 
 
Analysis of Paint Oils 409 
 
 After giving careful consideration to the work that was con- 
 ducted, the sub-committee was of the opinion that the most 
 satisfactory criterion for foots is the determination upon oil 
 that has been heated to 65° C., which gives a measure of the 
 mucilaginous material in the oil, and secondly a determination 
 upon oil which has been chilled to 0° C., which gives a meas- 
 ure of the mucilaginous material plus foots which are easily 
 solidifiable in the cold and which often separate from the oil 
 during cold weather. The committee suggested that 1% and 
 4% respectively of these constituents were proper maximum 
 limits for foots as determined under these two conditions. 
 
 Jameson-Baughman Foots Test.*—Weigh accurately 10 
 grams of the sample in a 50 ce. flask and transfer with the aid 
 of petroleum ether to a 500 cc. pear-shaped separatory funnel, 
 using in all 50 ce. of low boiling petroleum ether (B. P. less 
 than 80° C.). Have the stopeock of the separatory funnel 
 lubricated with water. Agitate the oil and petroleum ether 
 until a homogeneous solution is formed. Add 10 ec. of a 14 
 per cent potassium hydroxide solution, insert the stopper, and 
 shake vigorously for 3 minutes. Then add 25 ce. of 50 per 
 eent aleohol and shake for 15 or 20 seeonds. Allow to stand 
 until the mixture separates into 2 layers. If the alcohol-alkali 
 solution is allowed to remain in contact with the petroleum 
 ether solution too long there is danger of saponifying some of 
 the neutral oil. A contact of one-half hour will-not cause a per- 
 ceptible error and this time is more than ample to effect a good 
 separation of the layers. Draw off the lower layer and the 
 precipitate into a 200 ce. separatory funnel, and rinse the in- 
 side of the outlet tube of the 500 ec. separatory funnel with a 
 little petroleum ether. Add 20 ce. of petroleum ether to the 
 contents of the 200 ee. separatory funnel, shake, and allow the 
 layers to separate. Draw off the lower layer and the precipi- 
 tate into a 250 ec. beaker. Rinse the outlet tube of the separa- 
 tory funnel with petroleum ether into the beaker. Add the 
 upper layer to the main petroleum ether solution in the large 
 separatory funnel. Pour the alcohol-alkali solution back into 
 the 200 ce. separatory funnel and extract with another 20 ce. 
 portion of petroleum ether. Repeat this treatment a third 
 time to insure the complete recovery of neutral oil. Save the 
 alcohol alkali solution for the determination of the fatty acids. 
 Wash the petroleum ether solution of the oil three times with 
 15 ce. portions of 50 per cent alcohol and add the washings to 
 
 * Presented originally in Scientific Section Circulars for 1927-28. 
 
410 Analysis of Paint Oils 
 te 
 
 the aleohol-alkali solution in the 250 ce. beaker. Transfer the 
 solution of the oil to a weighed 300 cc. Erlenmeyer flask and 
 rinse the separatory funnel with several small portions of 
 petroleum ether. Distill off as much as possible of the solvent 
 by placing the flask in a water bath. Heat the flask in an oven 
 at 120° or 125°, using an atmosphere of carbon dioxide to pre- 
 vent oxidation of the oil, until a constant weight is obtained. 
 In most cases 2 hours’ heating is sufficient. Calculate the 
 percentage of neutral oil. | 
 Place the beaker containing the alcohol-alkali solution on 
 the steam bath and evaporate the alcohol. Then add about 
 75 ec. of water and, when the soap is dissolved, acidify the 
 solution with hydrochloric acid. Cover the beaker and heat 
 on the steam bath until the fatty acids have collected on top 
 
 TABLE 54 
 
 ANALYSIS OF RAW LINSEED OIL 
 Acid Acidity Iodine 
 
 Neutral Fatty value of as oleic number 
 Sample oil acids Break oil acid (Hanus) 
 % % % % 
 A, 8.7. Ms No. G0? soca s 98.32 1.26 0.42 2.23 1.12 179.5 
 : Mis RAE. Satan ore 98.35 1.22 0.43 Ee Pee ee ry 
 ASE OM: ING GL swiss toe 98.49 1.23 0.28 2.23 1.12 184.8 
 oh EN ates: oa ees eat 98.45 1.30 0.25 cies ae eee 
 A. 8:70. MANO: O2F oo ee 97.92 1.43 0.65 2.28 1.14 190.5 . 
 
 : Pe pen era or 97.93 1.45 0.62 teas 5 Gane Gears 
 
 - we gt Mera otanals ae 97.95 1.38 0.67 dices tye ¥ as ay 
 
 Ne: 1 (1924) wacom ees sexs 98.36 1,15 0.49 1.89 0.95 178.5 
 oie etalon als orale eeiar Bae 98.38 1.19 0.43 a ape sae 
 S82 ST a Veta eaeceei ie eae 98.39 1.20 0.41 
 
 ING, ss25G Rect oe eee 98.77 0.98 0.25 1.67 0.84 188.9 
 Been ee rs: ee cree ee a 98.69 0.98 0.33 a ot “Ae rey 
 INO) <3 opine wis sincere ehniees, meee 98.54 1.19 0.27 2.17 1,09 181.3 
 NO. “45%. a iis os ae ee eee oe eee 93,90" ae 0.26 1.26 63 186.3 
 Se Wine. 6 A ieget dea atria ee ee 98.96 0.75 0.29 va $l ie ee Davai 
 NO... Bois sh eee eee 98.18 1.38 0.44 2.35 1.18 184.0 
 pager Eyer ear ee Pies fy 98.16 . 1e¢ 0.47 Bene eae Stele 
 
 of the solution. Cool until the fatty acids become solid, filter, 
 and wash with water until the fatty acids are free from chlor- 
 ides. Place the funnel containing the filter paper with the 
 fatty acids in the 250 ec. beaker and heat on the steam bath 
 until beaker and filter are dry. Dissolve the fatty acids with 
 small portions of petroleum ether. If the solution of the fatty 
 acids is turbid, refilter it through the original filter. Collect 
 
 *Figures given under “Break” include also the foots. Each sample was 
 thoroughly mixed before analysis. These oils were kindly furnished by R. D. 
 Bonney, Chairman of A. 8S. T. M. Sub-committee V on Linseed Oil. 
 
 Oils 1, 2 and 3 were hot pressed and oils 4 and 5 were cold pressed. 
 
 Oils 1 and 2 were expressed from Argentine seed while 3, 4 and 5 were 
 obtained from American seed. 
 
Analysis of Paint Oils 411 
 
 the filtrate and washings in a weighed 200 cc. Erlenmeyer 
 flask. Remove the solvent as described for the determination 
 of neutral oil, and weigh. Calculate the percentage of fatty 
 acids. To obtain the per cent of break or break and foots, 
 subtract the percentages of neutral oil and fatty acids from 
 100. 
 
 The results obtained are given in Table 54. 
 
 Occasionally, after the withdrawal of the aleohol-alkali solu- 
 tion, a small quantity of a finely-divided precipitate gradually 
 separates from the petroleum ether solution of the neutral oil. 
 During the washing with 50 per cent alcohol, this precipitate 
 settles between the layers and it is usually safer not to with- 
 draw it with the wash solution as there is danger of losing 
 some neutral oil. In the few cases observed it has been found 
 possible to decant the petroleum ether from this slight pre- 
 cipitate. However, if necessary, the precipitate should be 
 removed by filtration. Then the greatest care must be taken 
 the all of the neutral oil from the filter with petroleum 
 ether. 
 
 From the results given, it will be observed that there is ap- 
 parently no relation between the quantity of break in an oil 
 and its iodine value. The one sample.with the highest iodine 
 number also contains more of the break than any of the other 
 samples given in the table. 
 
 A.S. T. M. TENTATIVE SPECIFICATIONS FOR BOILED 
 LINSEED OIL 
 
 PROPERTIES AND TESTS 
 
 1. Boiled linseed oil shall be pure linseed oil that has been treated by 
 heating and incorporating compounds of lead, and at the option of the manu- 
 facturer suitable compounds of other drying metals, so as to produce a 
 product that will dry rapidly. It shall be clear, free from sediment, and 
 shall conform to the following requirements, when tested in accordance with 
 the methods described in Sections 2 to 12, inclusive: 
 
 : Maximum. Minimum 
 
 Pomerorearving on glass; HOurs..........0.se00 18.0 Bete 
 Brecwmic Gravity, 15.5 /15.5° CC... 6 ec etse eee ens 0.945 0.951" 
 EMMETT TNS 6 hata, 6p (5. oo ne nie ois Sis a 9.0 cle ae om soe ete 7.5 re 
 mee OM ION INTIMIDED: «5s o.0 ic oie 0 9 6 «ord aye e eiele's 195.0 189.0 
 Unsaponifiable Matter, per cent..............0-. 1.50 A 
 Oiieemmmner ( WIjS). oc. ss cee eee siewceee eee eae 170.0 
 Loss on Heating at 105 to 110° C., per cent...... 0.2 BLO Y 
 RIUM RIT ge oo iokn a citi Gace Oka deldeve eae 0.50 ree 
 REECE TNT 500 a cine casio: tsg omg Ala gitat a ace 6 ace whe aon Cede 0.05 
 
 * When a high viscosity type of boiled linseed oil is required, the specific 
 gravity shall not be less than 0.937. 
 
412 Analysis of Paint Oils 
 
 METHODS OF TESTING 
 
 2. General.—All tests shall be made on oil that has been thoroughly agi- 
 tated before the removal of a sample for analysis. 
 
 3. Time of Drying on Glass.—In determining the time of drying on glass, 
 flow the sample over a perfectly clean glass plate. Place the plate in a 
 vertical position in air that is at 30° C.+2°C. and of a humidity of 32-per- 
 cent + 4 per cent saturation. After about two hours, test the film at intervals 
 with the finger at points not less than 2.5 em. from the edges. The film 
 shall be considered dry when it no longer adheres to the finger and does not 
 rub up appreciably when the finger is lightly rubbed across the surface. 
 
 4. Specific Gravity. In determining specific gravity, use a py knometer, 
 accurately standardized and having a capacity of at least 25 ce., or any other 
 
 equally accurate method, making the test at 15.5° C. water being 1.000 at 
 
 15.326; 
 
 5. Acid Number.—In determining acid number, weigh from 5 to 10 g. of the 
 sample. Transfer to a 300-ce. Erlenmeyer flask. Add 50 ec. of a mixture of 
 equal parts by volume of 95-per-cent ethyl alcohol and c.p. reagent benzol. 
 (This mixture should be previously titrated to a very faint pink with dilute 
 alkali solution, using phenolphathalein as an indicator.) Add phenolphthalein 
 indicator and titrate at once to a faint permanent pink color with 0.2 N sodium 
 hydroxide solution. Calculate the acid number (milligrams KOH required for 
 1 g. of the oil). 
 
 6. Saponification Number.—In determining saponification number, weigh 
 about 2 g. of the sample in a 300-cc. Erlenmeyer flask. Add 25 cc. of alcoholic 
 sodium hydroxide or potassium hydroxide solution. Put a condenser loop in- 
 Side the neck of the flask and heat on the steam bath for one hour. Cool, add 
 phenolphthalein as indicator, and titrate with 0.5 N H,SO,4. Run two blanks 
 with the alcoholic sodium hydroxide solution. These should check within 
 0.1 ce. of 0.5 N H,SO4. From the difference between the number of cubic 
 centimeters of 0.5 N H2SO,4 required for the blank and for the determination, 
 calculate the saponification number (milligrams KOH required for 1 g. of 
 the oil). 
 
 7. Unsaponifiable Matter.—In determining unsaponifiable matter, weigh 8 
 to 10 g. of the sample. Transfer to a 250-ce. long-neck flask. Add 5 ee. of a 
 strong solution of sodium hydroxide (equal weights of NaOH and H,O) and 
 50 cc. of 95-per-cent ethyl alcohol. Put a condenser loop inside the neck of 
 the flask and boil for two hours. Occasionally agitate the flask to break up 
 the liquid, but do not project the liquid onto the sides of the flask. At the 
 end of two hours, remove the condenser and allow the liquid to boil down 
 to about 25 ce. 
 
 Transfer to a 500-ce. glass-stoppered separatory funnel, rinsing with water. 
 Dilute with water to 250 cc. add 100 ce. of redistilled ether. Stopper and 
 Shake for one minute. Let stand until the two layers separate sharp and 
 clear. Draw all but one or two drops of the aqueous layer. into a second 500-ce, 
 separatory funnel and repeat the process using 60 cc. of ether. After thorough 
 separation, draw off the aqueous solution into a 400-ce. beaker, then the ether 
 solution into the first separatory funnel, rinsing down with a little water. 
 Return the aqueous solution to the second separatory funnel and shake out 
 again with 60 cc. of ether in a similar manner, finally drawing the aqueous 
 solution into the beaker and rinsing the ether into the first separatory funnel. 
 
 s 
 
Analysis of Paint Oils 413 
 
 Shake the combined ether solution with the combined water rinsings and 
 let the layers separate sharp and clear. Draw off the water and add it to the 
 main aqueous solution. Shake the ether solution with two portions of water 
 (about 25 ce. each). Add these to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water down to 
 the stop-cock and draw off until the ether solution just fills the bore of the 
 stop-cock. Wipe out the stem of the separatory funnel with a bit of cotton 
 on a wire. Draw the ether solution (portion-wise if necessary) into a 250-ce. 
 flask and distill off. While still hot drain the flask into a small weighed 
 beaker, rinsing with a little ether. Evaporate this ether, cool the beaker and 
 weigh. (The unsaponifiable oil from adulterated drying oils may be volatile 
 and aS a consequence may evaporate on long heating. Therefore, heat the 
 beaker on a warm plate, occasionally blowing out with a current of dry air. 
 Discontinue heating as soon as the odor of ether is gone.) 
 
 8. Iodine Number.—In determining iodine number, place a small quantity 
 of the sample in a small weighing burette or beaker. Weigh accurately. 
 Transfer by dropping from 0.09 to 0.15 g. of oil to a 500-ce. bottle, having a 
 well-ground glass stopper, or an Erlenmeyer flask, having a specially flanged 
 neck for the iodine tests. Reweigh the burette or beaker and determine the 
 amount of sample used. Add 10 cc. of chloroform. Whirl the bottle to dis- 
 Solve the sample. Add 10 cc. of chloroform to each of two empty bottles like 
 that used for the sample. Add to each bottle 25 cc. of the Wijs solution and 
 let stand with occasional shaking for 1 hour in a dark place at a temperature 
 of from 21 to 23°C. Add 10 ce. of the 15-per-cent potassium iodide solution 
 and 100 cc. of water. Titrate with 0.1 N sodiym thiosulfate, using starch 
 aS an indicator. The titrations on the two blank tests should agree within 0.1 
 ec. From the difference between the average of the blank titrations and the 
 titration on the sample and the iodine value of the thiosulfate solution calcu- 
 late the iodine number of the sample tested. (Iodine number is given in centi- 
 grams of iodine to 1 g. of the oil.) 
 
 Preparation of Wijs Iodine Monochloride Solution.—Dissolve iodine in 
 glacial acetic acid that has a melting point of 14.7 to 15° C. and is free from 
 reducing impurities in the proportion so that 13 g. of iodine will be present 
 in 1000 ce. of solution. The preparation of the iodine monochloride solution 
 presents no great difficulty, but it shall be done with care and accuracy in 
 order to obtain satisfactory results. There shall be in the solution no sensible 
 excess either of iodine or more particularly of chlorine over that required to 
 form the monochloride. This condition is most satisfactorily attained by 
 dissolving. in the whole of the acetic acid to be used the requisite quantity 
 of iodine, using a gentle heat to assist the solution, if it is found necessary. 
 Set aside a small portion of this solution while pure, and pass dry chlorine 
 into the remainder until the halogen content of the solution is doubled. Ordi- 
 narily, it will be found that by passing the chlorine into the main part of the 
 solution until the characteristic color of free iodine has just been discharged, 
 there will be a slight excess of chlorine, which is corrected by the addition 
 of the requisite amount of the unchlorinated portion until all free chlorine 
 has been destroyed. <A slight excess of iodine does little or no harm, but 
 excess of chlorine must be avoided. 
 
 9. Loss on Heating at 105 to 110° C_—In determining the loss on heating, 
 place 10 g. of the Sample in an accurately weighed 50-cc. Erlenmeyer flask 
 
414 Analysis of Paint Oils 
 deanna eer eee eee errr errr eee 
 and weigh. Heat in an oven at a temperature between 105 and 110° C. for 30 
 minutes, then cool and weigh. Calculate the percentage loss. This determina- 
 tion shall be made in a current of carbon dioxide gas. 
 
 10. Ash.—In determining ash, weigh a porcelain crucible or dish. Add 
 from 10 to 25 ce. of the sample, carefully weighing the amount added. Place 
 on a stone slab on the floor of a hood. Ignite by playing the flame of a burner 
 on the surface of the oil and allow to burn quietly until most of the oil is 
 burned off; then transfer to a muifle or over a flame and continue heating at a 
 low temperature (not over a dull red) until all carbonaceous matter is con- 
 sumed. Cool, weigh, and compute the percentage of ash. 
 
 11. Leads.—In determining lead, dissolve the ash in dilute nitric acid to 
 which a little hydrogen peroxide has been added and determine lead by the 
 sulfate or any other equally accurate method. 
 
 12. Appearance.—Transfer a portion of the sample to a clear glass tube 
 and note appearance. 
 
 There is presented below a method which has been used sat- 
 isfactorily for purifying alcohol which is to be employed in the 
 determination of unsaponifiable matter. A reference is also 
 made to the Kerr-Sorber test for unsaponifiable matter, which 
 has been used with satisfactory results by Dr. G. 8. Jamieson. 
 
 Purifying Alcohol for Unsaponifiable—If necessary to 
 purify the alcohol, proceed as follows. To each liter of alcohol 
 add about a gram of silver nitrate dissolved in 2-3 ce. of water. 
 Then add 3 g. of potassium hydroxide (for each liter of alco- 
 hol) previously dissolved in about 20 ce. of alcohol, shake, and 
 allow the mixture to stand for at least two days in a flask with 
 a small beaker inverted over the neck. Either the clear al- 
 eohol may be decanted or filtered from precipitate. | 
 
 Kerr-Sorber Test for Unsaponifiable Matter.*—Accurately 
 weigh about 5 grams of sample into a 200 ml. Erlenmeyer 
 flask. Add 30 ml. of the aleohol and 3 ml. of the concentrated 
 potassium hydroxide (1:1 aq.) solution. Place a small, short- 
 stemmed funnel in the neck of the flask to serve as a conden-- 
 ser. Boil gently on the steam bath for about 20 minutes or 
 until complete saponification occurs. Cool to about 30° C., 
 add 50 ml. of ether U. S. P., mix, and transfer to a 500 ml. 
 separatory funnel. Rinse the flask with two successive 50 
 ml. portions of ether, add to the separatory funnel, and mix 
 thoroughly. Wash the saponification flask with 100 ml. of 
 dilute potassium hydroxide solution (0.2 N) and pour into the 
 separatory funnel in a slow, steady stream. Rotate the fun- 
 nel very gently to secure better contact of the solutions but do 
 not shake. (Shaking at this stage brings about stubborn 
 
 * Kerr-Sorber Method modified by Hertwig, Jamieson, Baughman and 
 Bailey. J. Assoc. Off. Agric. Chemists. Vol. VIII, p. 439-442 (1925). 
 
Analysis of Paint Oils 415 
 
 emulsions.) Allow the liquids to separate completely and 
 then slowly draw off as much of the soap solution as possible. 
 Do not draw off any layer of emulsion that may be formed. 
 Keep the volume of the ether at about 150 ml. by replacing 
 that dissolved by the wash solutions. Further treat the ether 
 solution with two successive 100 ml. portions of the alkaline 
 wash solution in the manner described previously. Add 30 
 ml. of water to the ether and rapidly rotate the liquid layers. 
 When the layers have separated completely, draw off the 
 water. Repeat this treatment until the washings are free 
 from alkal, as shown by testing with phenolphthalein. Three 
 washings usually suffice. Transfer the ether solution quanti- 
 tatively through a pledget of cotton in the stem of a funnel 
 to a weighed 250 ml. Erlenmeyer flask or beaker-flask. Before 
 weighing the flask dry it in an oven at 100° C., and then allow 
 it to stand in the air to constant weight. Distill off the ether 
 on a hot plate, cool and weigh. The unsaponifiable matter 
 from adulterated drying oils may be volatile mineral oil. 
 Therefore, it is well to occasionally blow out the ether with 
 dry air and discontinue heating when the odor of ether is 
 gone. 
 
 HExaBROMIDE Test FoR DETERMINING Purity oF LINSEED OIL 
 
 The determination of the hexabromide value of linseed oil 
 is probably the only method whereby adulteration with small 
 amounts (5 per cent or greater) of soya bean or some similar 
 oil ean be detected. This test shows the percentage of ether- 
 insoluble bromides which can be formed from the mixed fatty 
 acids of a given sample of linseed oil. 
 
 It has been found that the Steele-Washburn method for 
 hexabromides yields a fairly constant figure of 46 per cent for 
 unadulterated commercial oils. 
 
 Soya bean oil has been found to yield not over 6 per cent 
 of hexabromides, while cottonseed oil shows a zero yield. 
 
 The calculation given below will indicate how an addition of 
 10 per cent soya bean oil to linseed oil will not lower the iodine 
 value below the allowable minimum but will lower the hexa- 
 bromide value to a marked degree: 
 
 Assume a linseed oil with iodine number of 185 to be adul- 
 terated with 10 per cent of soya bean oil, iodine value of 130. 
 
 Then: .90 « 185 = 166.5 
 LO < 180 ==" 13.0 
 
 Iodine number of mixture = 179.5 
 
416 Analysis of Paint Oils 
 
 a. 
 Assume that the same linseed oil has a hexabromide yield of 
 46 per cent while the soya bean oil yields 6 per cent of hexa- 
 
 bromides. 
 Then: .90 x 46— 414 
 AO ae Ga 6 
 
 Hexabromide yield of mixture=— 42.0 
 
 A hexabromide yield of 42.0 per cent would be much lower 
 than any normal linseed oil and would indicate adulteration, 
 while an iodine number of 179.5 would not indicate adultera- 
 tion. 2 
 
 The two methods (Steele and Washburn or Bailey’s modi- 
 fication thereof) by which the hexabromide test may be made, 
 are given below. The Bailey modification differs from the 
 Steele and Washburn method in that an acetic acid-bromide 
 solution is used instead of a chloroform-bromide solution. The 
 Bailey modification also entirely eliminates the use of chloro- 
 form from the reaction mixture and does not require ‘‘amy- 
 lene’’ or other reagent for removing the excess of bromide 
 after the bromination of the fatty acids. The Bailey modifica- 
 tion, however, requires the precipitated hexabromides to first 
 stand over night in an ice chest instead of immediate washing. 
 
 Steele erd Washburn Method.—The following reagents are 
 necessary : 3 
 
 1. Chloroform.—Shake ordinary U. 8. P. chloroform with 
 several portions of water to wash out all the aleohol. Dry the 
 product with granulated anhydrous calcium chloride over 
 night in order to remove all traces of water. Decant from the 
 calcium chloride and distil. Add to the distillate 3 ec. of abso- 
 lute ethyl aleohol for every 100 ee. of chloroform. Keep in a 
 stoppered brown bottle. 
 
 2. Bromide Solution——Mix one part by volume of C. P. bro- 
 mine* with two parts by volume of chloroform, prepared as 
 above. This solution must be made up fresh each day because 
 it deteriorates upon standing. 
 
 3. Wash Ether—Shake ordinary ethyl ether with 10 per 
 cent of its volume of ice cold distilled water. Separate and 
 repeat the washing three times. Dry the washed ether with 
 fused calcium chloride overnight. Decant the ether through a 
 
 * The authors have observed that samples of bromine marked “C. P.” 
 often contain considerable amounts of non-volatile material. All bromine 
 which is used must be redistiled unless it is found that 5 gms. leave no 
 weighable residue upon evaporation. 
 
Analysis of Paint Oils 417 
 
 folded filter into another flask and add thin slices of sodium. 
 Warm gently on a steam bath under a reflux condenser until 
 the evolution of gas by action of the sodium has practically 
 ceased and bits of freshly cut sodium remain bright in the 
 ether. Distill the ether into a dry bottle and add an excess 
 (at least three grams per liter) of finely powdered hexabrom- 
 ide of the fatty acids of linseed oil previously prepared. If 
 no hexabromide is on hand from previous determinations it 
 may be easily prepared as follows: In a centrifuge tube dis- 
 solve about 5 grams of the fatty acids of linseed oil in 15 to 20 
 ec. of chloroform. Place the tube in a freezing mixture and 
 add slowly, with shaking, bromine solution until a shght red 
 color is permanent. Adda few drops of amylene to ile up 
 excess of bromine. Whirl ina centrifuge until the precipitate 
 has settled and then pour off the chloroform. Rub up the 
 precipitate with 20 cc. of cold absolute ether, whirl in a cen- 
 trifuge and pour off the wash ether. Repeat the washing 
 with 3 more 20 ec. portions of ether. After drying, the hexa- 
 bromide is pure enough for the preparation of wash ether. 
 Shake at intervals for two or three hours or allow the mixture 
 to stand over night. Then place the bottle in ice water so that 
 the ether solution will be at zero or not above 2° C. for three 
 hours. Decant the ether solution rapidly through a folded 
 filter into a dry bottle and keep tightly corked in Ante to 
 prevent loss of ether by evaporation. 
 
 4. Amylene.—This material may be pur a ice ane 
 Kastman Kodak Company. It is one of the organic chemicals 
 prepared in the laboratory of the University roe LL rOveste cLt 
 may be prepared in small quantities from amyl alcohol by the 
 method of Adams, Jour. Am. Chem. Soc., 1918, page 1950. 
 
 B. Preparation of the Fatty Acids. 
 
 Weigh approximately 50 grams of linseed oil into a 11% liter 
 Florence flask, and add 40 ce. NaOH solution (sp. gr. 1.4) and 
 40 ee. of aleohol. Place the mixture on a steam bath and heat 
 for about 14 hour. Add 1 liter of hot distilled water and in- 
 sert into the neck of the flask a 2-hole rubber stopper carrying 
 a tube which projects into the flask so that its end is slightly 
 above the liquid, and pass a stream of COz2 through the tube 
 into the flask. The soap mixture may then be heated, to re- 
 move the alcohol, either over a free flame or on the steam bath. 
 If the free flame i is used, a capillary ‘‘boiler’’? must be placed 
 in the liquid, since otherwise the soap solution will bump badly. 
 If excessive foaming takes place the current of CO» should be 
 increased until it is strong enough to break da the foam. If 
 
418 Analysis of Paint Oils 
 
 the solution is heated on the steam bath, usually about 2 or 3 
 hours is required to remove the alcohol, while if it is boiled 
 over a free flame, one-half hour is usually sufficient. After the 
 alcohol has been removed, cool the soap solution and acidify 
 with dilute HCI (1-1). Insert a 3-hole rubber stopper, carry- 
 ing two glass tubes arranged as for a wash bottle, leaving the 
 third hole in the stopper open for an outlet for the COs. The 
 inlet tube should extend to just above the layer of fatty acids, 
 and the outlet tube should extend to the bottom of the flask. It 
 is essential that the outlet tube should not extend down more 
 than an inch or two outside of the flask, as otherwise siphoning 
 would take place, causing the liquid to boil inside the tube. 
 
 Pass a stream of CO: through the system, and boil gently, 
 using a capillary boiler to prevent bumping, until the layer of 
 fatty acids is clear. Plug the hole in the stopper which acts as 
 an outlet for the COz. The lower layer will be forced out 
 through the outlet tube by the pressure of the CO,. In this 
 manner remove as much water as possible without losing any 
 of the fatty acids, then remove the stopper and add about 500 
 ee. of hot distilled water, shake thoroughly so that the fatty 
 acids are well washed, allow the fatty acids to separate and 
 siphon off the wash water as before. Repeat the washing until 
 the wash water does not give an acid reaction with methyl 
 orange. Before removing the last washing, insert a capillary 
 boiler and boil gently until the fatty acid layer is clear. After 
 the last washing, remove the stopper and suck up with a pip- — 
 ette the last few globules of water. Filter the hot fatty acids 
 through a folded filter under an evacuated bell jar and keep in 
 a well stoppered bottle. 
 
 C. Preparation of Hexabromides. 
 
 Weigh accurately in a weighed centrifuge tube (approxi- 
 mately 614 inches long by 1 inch in diameter) 1.00 gram (plus 
 or minus 0.05 gram) of linseed fatty acids, prepared as given 
 above. Dissolve in 10 ce. of chloroform and place the tube in a 
 freezing mixture kept as near—5° C. as possible, made by 
 adding a little dilute hydrochloric acid to finely eracked ice. 
 Add bromine solution from a burette at the rate of one or two 
 drops per second, shaking the tube well during the addition. 
 At first the bromine color will be rapidly discharged, but later 
 the mixture will assume a permanent orange color indicating 
 a slight excess of bromine. For most fatty acids of linseed 
 oil about 1 cc. of the bromine solution will be found necessary 
 to give the orange color. At this point run in rapidly 0.5 ce. 
 more of the bromine solution, shake well, and allow the tube 
 to stand in the ice mixture for ten minutes. Remove the tube 
 from the freezing bath and add amylene drop by drop with 
 shaking until the bromine color has entirely disappeared. 
 
Analysis of Paint Oils 419 
 —$—<— eee 
 Usually five to six drops of amylene are sufficient, but a slight 
 excess does no harm. The addition of bromine solution must 
 never be done in direct sunlight. 
 
 Attach the tube to a good water vacuum pump (one which 
 will indicate a pressure not greater than 40 mm. of mercury ) 
 by means of a new one-hole rubber stopper. Eivaporate the 
 chloroform in a vacuum, warming the tube in water at 50 to 
 60° C. to hasten evaporation. The tube must be constantly 
 shaken to prevent bumping of the chloroform. Towards the 
 end of the evaporation, when the contents of the tube become 
 more viscous, rotate and tilt the tube so that the oil will flow 
 about half way up the sides and thus present more surface for 
 evaporation. When practically all the chloroform has been 
 evaporated, place the tube in a bath at 55 to 60° C. for fifteen 
 minutes, keeping the suction on. | 
 
 Detach from the pump and place the tube in a bath of finely 
 eracked ice and water. When the tube is cold pour down its 
 sides 20 ec. of cold wash ether, as prepared above. The wash 
 ether should have been previously placed in four corked test 
 tubes graduated at 20 ce. by a file mark and kept at 0° C. in an 
 ice bath. Thoroughly stir and rub up the bromide mixture 
 with a rod, breaking up all the lumps. “Return the tube to the 
 ice bath for two minutes and then whirl in a centrifuge until 
 the precipitate has settled into a hard cake and the super- 
 natant liquid is clear. Return the tube to the ice bath for two 
 minutes and then pour off the wash ether, making sure that no 
 _ solid material is lost. Repeat the washing of the hexabromide 
 precipitate three times in exactly the same way, using three 
 20 ee. portions of ice-cold wash ether and rubbing up the pre- 
 cipitate thoroughly each time. Use a weighed stirring rod and 
 wash the precipitate adhering to the rod into the tube with 
 the wash ether at each washing of the hexabromide. After- 
 wards dry and weigh the rod plus the slight coating of precipi- 
 tate and add the weight of material on the rod to the weight 
 of the main portion of hexabromide. After the fourth ether 
 washing has been poured off, carefully incline and tap the tube 
 and spread the hexabromide precipitate part way up the sides. 
 Warm the tube in water at 50 to 60° C. until most of the ether 
 has evaporated. Attach to the suction pump and place the 
 tube in a bath at 60 to 70° C. for fifteen minutes. Detach the 
 tube from the pump, cool in cold water to room temperature, 
 wipe dry with a towel and weigh at once. Dry the tube to con- 
 stant weight in an oven at.100-110° C. The total weight of the 
 precipitate times 100 divided by the weight of fatty acids 
 taken, gives the hexabromide percentage. The hexabromide 
 should dry pure white. 
 
420 Analysis of Paint Oils 
 
 Special Precautions: 
 
 1. Have the chloroform dry and adjust its alcohol content 
 to 3 per cent. 
 
 2. Make sure that all the chloroform is evaporated from the 
 impure hexabromide before adding wash ether. This will be 
 accomplished if the water pump indicates a pressure not 
 ereater than 30-40 mm. and the tube is heated in the bath at 
 60° C. for two-thirds of its lengths. 
 
 3. Make sure that the wash ether is anhydrous and free from 
 alcohol and that it is saturated with hexabromide at 0° GC. Un- 
 less the wash ether is allowed to stand at 0° C. for a sufficient 
 length of time before filtering off excess hexabromide, it will 
 be super-saturated at 0° C. and will give high results. Care 
 should be taken to prevent appreciable loss af ether by evap- 
 oration; it is well to cool the stock bottle of wash ether on hot 
 days before uncorking. 
 
 4. Make sure that the centrifuge tube containing hexabro- 
 mide and the wash ether are kept as near 0° C. as possible dur- 
 ing the process of washing. The finely cracked ice should be 
 replenished at intervals. 
 
 5. It has been found that low and non-coneordant hexabro- 
 mide results on pure linseed oil by the new method can nearly 
 always be traced to the use of a faulty vacuum pump or to 
 faulty rubber connections. Therefore, the operator should 
 convince himself by test with a mercury manometer immedi- 
 ately before making the determination that his pump, as used, 
 will give a vacuum of not greater than 30 mm. mercury. Heavy 
 walled pressure tubing should always be used for connections. 
 A faulty pump or faulty rubber connections usually means 
 that the chloroform is not all evaporated from the impure 
 hexabromide and will exert a solvent action on the hexabro- ~ 
 mide later on, thus giving low yields. 
 
 6. If a Nelson rotary oil pump is available, it is an excellent 
 plan to remove the last traces of chloroform by attaching the 
 centrifuge tube to this type of pump for 15 minutes. The bulk 
 of the solvent should be removed first by means of the water 
 pump 
 
 F. W ith either pump the tube should be heated in a bath of 
 ae 65° C., during the evaporation of the last traces of chloro- 
 
 orm. 
 
 BatLtey’s MoptricaTION oF STEELE AND WASHBURN MerrHop FOR 
 HEXABROMIDE NUMBER 
 Principle: 
 The unsaturated fatty acids when treated under proper con- 
 
_ Analysis of Paint Oils 421 
 
 ditions with bromine absorb at each unsaturated linkage two or 
 more atoms of bromine depending on the degree of unsatur a- 
 tion. Thus at a double bond—C— —C—there is obtained a satu- 
 rated bromo product : rothren 
 
 | 
 Br Br 
 four bromine atoms are absorbed to give a saturated compound 
 Bc. 3r 
 
 co The solubility in ether of the bromo derivaties de- 
 | | 
 br. Br 
 
 creases rapidly with increase of bromine content. Thus the di 
 and tetra bromo compounds are easily soluble, whereas the 
 hexa (and octo) compounds are only very sparingly soluble. 
 This fact is made use of to separate the hexa (and octo) bromo 
 deriviaties in carrying out the analytical determination. 
 
 Status: 
 
 The following method is applicable to the determination of 
 the hexabromide number of saponifiable oils. It must be re- 
 membered that the hexabromide nuniber depends upon the 
 method employed in making the determination. It is, there- 
 fore, important that in reporting results, the particular 
 method must be specified. | eae 
 
 Reagents and Apparatus: 
 (a) Reagents: 
 (1) C. P. sodium hydroxide solution of 1.4 sp. gr. 
 (2) 95% alcohol. 
 (3) Distilled water. 
 (4) C. P. hydrochlorie acid. 
 (5) CO, or nitrogen. 
 (6) C. P. bromine containing no non-volatile matter. 
 (7) Glacial acetic acid showing no reduction with 
 
 dichromate or permanganate in the usual test. 
 (8) Wash ether. 
 
 REFERENCES.—The following are the recent references of value: Chem. 
 Tech. and Anal. of Oils, Fats and Waxes, by Lewkowitsch, 5th Ed., Vol. I, p. 
 568; Farben Zeitung (1912) No. 3 ff.; Muggenthaler, Inaug. Dissert. 1912. 
 Augsburg: Bailey and Johnson, J. I. E. Wal 10, 999 
 
 Shake ordinary ethyl ether with 10% of its volume of ice- 
 cold distilled water. Separate the water and repeat the wash- 
 ing three times. Dry the washed ether with fused calcium 
 chloride over night. Decant the ether through a folder filter 
 
422 Analysis of Paint Oils 
 
 into another flask and add thin slices of sodium. Warm gently 
 on a steam bath under a reflux condenser until the evolu- 
 tion of gas by action of the sodium has practically ceased and 
 bits of freshly cut sodium remain bright in the ether. Distill 
 the ether into a dry bottle and add an excess (at least 3 grams 
 per liter) of finely powdered hexabromide of the fatty acids 
 of linseed oil previously prepared. (If no hexabromide is on 
 hand from previous determinations, it may be prepared as fol- 
 lows: In a centrifuge tube dissolve about five grams of the 
 fatty acids of linseed oil in 25 cubic centimeters of ether. 
 Place the tube in a freezing mixture and add slowly with shak- 
 ing bromine solution until a red color is permanent. Let stand 
 for at least fifteen minutes and then whirl the tube in a centri- 
 fuge until the precipitate has settled and then pour off the 
 ether. Rub up the precipitate with 20 cc. of cold absolute 
 ether, whirl in a centrifuge and pour off the wash ether. Re- 
 peat the washing with 3 more 20 cubic centimeter portions 
 of ether. After drying the hexabromide so obtained is pure 
 enough for the preparation of the wash ether.) Shake at in- 
 tervals for two or three hours or allow the mixture to stand 
 overnight. Then place the bottle in ice water so that the ether 
 solution will be at zero or not above 2° C. for at least three 
 hours. Decant the ether solution rapidly through a folded 
 filter into a dry bottle and keep tightly corked in order to 
 prevent the loss of ether by evaporation. 
 
 (b) Apparatus: 
 
 (1) Steam bath. 
 (2) Gas burner. 
 
 (3) Iron tripod, ring stand and wire gauze. 
 (4) Round bottom flask of 2 liters capacity. 
 (5) Separatory funnel, 500 ce. 
 (6) Bell jar. 
 (7) Well annealed test tubes 5” x 1”. 
 (8) 50 ce. burette. 
 - (9) Glass stirring rods 6” x 3/16”. 
 (10) Glass battery jars. 
 (11) Graduated cylinders 10 and 50 ee. capacity for 
 weighing out samples 
 (13) Centrifuge giving about 3,000 R. P. M. 
 (14) A vacuum showing no higher than 40 mm. press- 
 ure. 
 Determination: 
 
 (a) Preparation of fatty acids—Weigh approximately 50 
 grams of oil into a 2 liter round-bottom flask and add 40 ee. 
 of NaOH solution (sp. gr. 1.4=36.50% sol.) and 40 ee. of alco- 
 
Analysis of Paint Oils 423 
 
 hol. Place the mixture on a steam bath and insert a 2-hole 
 rubber stopper into the neck of the flask carrying a tube which 
 projects into the flask so that its end is just above the liquid. 
 Heat for about one-half hour, passing a stream of CO2 through 
 the apparatus all the while. Add one liter of hot distilled 
 water and boil the soap solution to remove the alcohol, either 
 over a free flame or on a steam bath. If a free flame is used 
 about one-half hour’s boiling will be sufficient, but it may be 
 necessary to insert capillary tubes to prevent bumping of the 
 liquid. If the solution is heated on the steam bath, usually 2 
 to 3 hours are required. After removing the alcohol, the solu- 
 tion is cooled somewhat and then acidified with dilute HCl 
 (1:1). Warm the mixture until the fatty acids form a clear 
 layer, continuing to pass CO2 through the system all the time. 
 The fatty acids are separated from the aqueous layer by means 
 of a 500 ee. separatory funnel. The funnel is filled with the 
 mixture, and the fatty acids will float on top, and the aqueous 
 portion is run off. The remainder of the mixture in the flask 
 is added to the funnel and the aqueous portion again run off. 
 A brisk stream of CO, is passed into the funnel to replace the 
 air. 300 ce. of hot distilled water is added and the mixture 
 is vigorously shaken. After the fatty acids collect on top the 
 aqueous portion is run off. This washing is repeated until the 
 water is neutral to methyl orange, three washings usually 
 being sufficient. The warm fatty acids are run into a centri- 
 fuge tube (1" x 5”) and whirled for about one minute to collect 
 any remaining water at the bottom. They are then filtered by 
 decantation on to a folder filter under an evacuated bell jar 
 and kept in a well-stoppered bottle. 
 
 (b) Preparation of the hexabromides.—Weigh accurately in 
 a weighed contrifuge tube (1” diam. x 5” long) as nearly as 
 possible one gram of fatty acids. It was found that in the 
 case of linseed oil better results are obtained by keeping the 
 weight of the sample as near to one gram as possible, so the 
 deviations from this should not be more than plus or minus 
 0.02 gram. Dissolve the fatty acids in 25 ee. of the specially 
 prepared ether and place the tube in a freezing mixture kept 
 at about —d° C. made by adding a little HCl to finely cracked 
 ice. Add bromine solution* from a burette at the rate of 
 about one or two drops per second, shaking the tube well dur- 
 ing the addition until a deep red color is produced. This 
 should not be done in direct sunlight. The tube is then al- 
 lowed to stand in an ice chest overnight (about 14 hrs.), the 
 
 *5 ec. bromine, 25 ec. glacial acetic acid made up just before use. 
 
424 Analysis of Paint Oils 
 ei eee 
 
 proper ‘precautions: being taken to prevent the loss of solvent 
 by evaporation by inserting a stopper. —. 
 
 It is necessary to let the tube stand.for this period: of time 
 because in the case of oils which contain only a small amount 
 of linolenic acid (soya bean oil is a good example) the precipi} 
 tation of the hexabromide proceeds more slowly than in the 
 ease of an oil with a larger content of lmolenie. acid eee 
 for example). 
 
 Next morning cool the tube by immersion in a bath of 
 eracked ice and rub up the precipitate by means of a weighed 
 glass rod, being sure to loosen any material adhering to the 
 side of the tube. Whirl the tube in a centrifuge till the pre- 
 eipitate forms a hard cake on the bottom, cool in the ice bath, 
 and decant the ether. Add 20 cc.-of the wash ether previously 
 prepared and cooled to 0° C. and Yub up the precipitate with 
 the glass rod. Return the tube to the ice bath and when cold 
 whirl it in the centr ifuge.- Return the tube to the ice bath and 
 then remove the ether by’decantation: Repeat this washing 
 twice more. After the last washing incline the tube and ecare- 
 fully tap it to spread the hexabromide precipitate part of the 
 way up the sides: - Warm the tubein water at 60° C. until most 
 of the ether has evaporated, then attach it for 15 minutes to a 
 vacuum line showing a:pressure of 30-40 mm. keeping the tem- 
 perature around 60° C. Wipe the tube dry and allow it to 
 stand in the balance at least 15 minutes before weighing. To 
 the weight of the precipitate in the tube add the weight of the 
 sight amount adhering to the glass rod. This total weight 
 of precipitate multiplied by 100 and divided by the weight of 
 fatty acids taken, gives the hexabromide percentage. 
 
 Notes: (1) The fatty acids are used instead of the glycerl- 
 esters because the latter give inconcordant results. 
 
 (2) In the case of linseed oil, the weight of the sample 
 should be kept as near one gram as possible. 
 
 (3) Care should be exercised in preparing the wash ether 
 for if it is unsaturated with hexabromides according to direc- 
 tions, the results will be low. 
 
 CO-OPERATIVE WORK ON HEXABROMIDE METHODS 
 AS CONDUCTED BY SUB-COMMITTEE It OF 
 COMMITTEE D-1, A. 8. T. M. | 
 
 Comments made by the various observers are abstracted 
 
 herewith: | 
 
 S. and P. Waldstein state that when a large per- 
 centage of soya bean oil is present in an oil there-is 
 formed a large percentage of tetrabromide which may 
 
Analysis of Paint Oils 425 
 a __________ 
 
 not be completely washed out. They recommend in 
 such instances to increase the portions of ether to 25 
 or 30 ee. or to increase the number of washings to 9 or 
 6 in order to overcome high results, 
 
 The chairman of the sub-committee has done some 
 experimental work with the idea of developing a 
 method of determining the hexabromide value of oils 
 volumetrically. It was found that the bromine ab- 
 sorption number of the fatty acids of linseed oil-were im 
 higher than for soya bean oil in some’ preliminary . 
 volumetric work. It is known that the bromine, sub- 
 stitution number of linseed oil fatty acids is low while 
 
 TABLE 55 
 
 THE RESULTS OF VARIOUS OBSERVERS WORKING ON LWwo. 
 Os ARE GIVEN IN THE TABLE BELOW. . 
 
 HEXABROMIDE VALUES 
 Bailey 
 
 Steele-Washburn Method : _ Modifica- 
 tion of | 
 al a ai . 
 . ashburn 
 z Ree Be ike Method - 
 Oils a go ao) = € 4 
 © a . sy ; a 3 34 Sn : 
 ‘ tie pete Ge say ae ek Be Choe 
 ‘ omc) o g po = a) =| is) | uu 'g x) bp 
 eae re iets ee 8 a2 ee ae ¢ @ 58 
 = coj> hes aen © a Mm A = = Oe eat 
 100 per cent Pure Raw Linseed Oil.... 45.9 46.4 46.6 45.4 46.0 46.2 46.6 45.4 46.1 40.5 42.7 41.6 
 85 per cent Pure Raw Linseed Oil.. 
 15 per cent Soya Bean Oil................ } SUES I eae 41.8 39.1 41.9 39.8 41.9, 39.1 40.4 34.9 37.5 Ee 
 
 75 per cent Pure Raw Linseed Oil.. 3 . 
 O5 uct cent Gova-Bean Oil.............. : 36.4 38.4 38.2 36.0 37.2 36.1 38.4 36.0 ae 31.5 34.5 33.0 
 
 le Gata theta Raw Linseed Oil.) 30.8 38.4 34.8 30.5 38.8 33.5 34.8° 30.5 32.8 26.7 31.4 29.6 
 the fatty acids of soya bean oil have a low addition 
 number. Considerable further work, however, will 
 be necessary in order to develop a method that will be 
 satisfactory. 
 
 Conclusions.—The Steel-Washburn method of determining 
 hexabromides has given closely concordant results in the 
 hands of several different operators, and is apparently well 
 adapted for determining the purity of raw linseed oil. It is 
 recommended that further work be carried on with the object 
 of shortening the method. 
 
 Through the kindness of Mr. Herbert S. Bailey and Mr. 
 Baldsiefen of the Experimental Station, E. I. du Pont de Ne- 
 mours & Co.; there are presented herewith two tables (56 
 and 57) showing the iodine and hexabromide numbers of raw 
 and treated linseed oils, and of soya bean oil, tung oil, and 
 
426 Analysis of Paint Oils 
 
 TABLE 56.—Jodine and hexabromide numbers of raw and treated 
 linseed oil 
 
 OL Iodine . 
 Hexabromide No. 
 No. Substance No. 
 pees Steele Method 
 By A j ByB 
 553 Linseed oil from North American seed..... 176.2 42 0 
 : M 6 oat ee 45. 
 sa | 46.3 
 553 < S ae 2 2 tS See 46.5 
 553 . ttn: 4 : Oo eit ae 46.3 
 553 m ose : e 4 + ee ee 43.6 
 553 « « ria “ “« “ 5 39.2 
 553 Ss Nhat . ‘ EMP Py 39.1 
 565 | Linseed oil, commercial refined............ 176.5 44.0 
 563 . n Z PAW 65 ee 185.0 43.6 
 ee | ee 
 574 Linseed oil (Bu. of Stds. sample) RRM en 4: 183.0 47.6 
 sa) oe ee 
 574 Se haem eae en 
 574 « «“ « “ « « | 46.2 
 pa | ee 6 
 535 | Lins’d oil Ext’d from Argentine seed....... 189.8 50.0 49.7 
 535 “ a“ “ “ “ {9 50 8 
 pp | ee 
 641 OL 553 + 5% (1) tung oil drier 727 166.8251). Ae se 
 641 : MC 
 “ “& «“ “ “ 
 eg |g 
 643 ee Se 208, SS, Se 152 6.3]. See 41.8 
 643 ait : CO ee ee 42.2 
 — 2 " + 5% grinding japan .. 3. see 164,81) ea ones 
 64 " : MS elk o oun eh ip Le ee ; 
 ey 8 “ +10% ‘ GC oe ae 158.9 eae ee 
 5 : - : Opa vee ee L 
 ih ; + 20% : pike 147.43 ee ae 
 588 « « + 10% (*) linoleate driet..7.meeme "165.6 43.6 
 ae ‘S20 : al 45.3 
 po |< « eS 
 oF 5 “+ 0.2% manganese driert epee tN 168 .6 oie: 
 = o> ee OS eee : a 32.6 
 561 | Linseed oil, commercial... <3: > .3.eee 17a 41.8 
 561 sg “ boiled... 0.00.02. 525.00 5. 5 
 359 = “ heavy bodied =...) ae pee 80.8 11.3 
 
 various mixtures thereof. It is believed that the data pre- 
 sented in these tables will be of great service to the paint 
 chemist who intends to carry on hexabromide work. 
 
 (*) Added without treating oil. 
 (+) Manganese linoleate boiled in at 250° C. 
 
Analysis of Paint Oils 427 
 ee ER AR a, el 
 
 TABLE 57.—lodine and hexabromide numbers of soya bean, tung and lin- 
 seed-soya bean mixtures 
 
 $y CE 
 os os 
 BE ee Fae 
 Ceara: ea 
 i) 
 OL a eee Vee sser ES 
 as Bo S38 
 No. ubstance £5 2s : e 
 < ss 
 ; By A By B. | By B. 
 310 | Soya bean oil, raw................ 13322 bet G5 4.2 
 310 . | SS Oe keer eeeeiae eS he SAN terre acs 4.9 
 310 pan Rete ere CO eng oes 3.6 
 565 | Soya bean oil, raw commercial. .... 133.2 1.5 
 565 <3 he Namie ooh ig SRE CNet Fc Saye 5.0 
 658 : Baer pressed. yo... |. ci cc ule nc ces 8.41 (OP#s 
 658 y: Depa Deere ea es ne. na ee 9.38 7.54 
 G59 | Soya bean oil, cold pressed........|........|........ 5.95 5.35 
 659 : emer © ST . Csce VER On Raga ctel aR ee a 5.76 5.65 
 Grove Hean oil,,extracted..:........|......00c)oc 00... 3.9 
 Se STE a ee De 0.0 0.0 
 572 50% OL 553 + 50% OL 310....|........ 26.0 23.0 
 572 Abe © rte ts ian Pea) nc et 23.6 
 572 50% OL 553 + 50% OL 670....|........ ee 24.3 23.3 
 572 7 ee OE Ele RO SiR atte Ee 24.6 24.3 
 
 A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
 
 RAW TUNG OIL 
 
 I. PROPERTIES AND TESTS. 
 1. Raw tung oil shall conform to the following requirements: 
 Maximum. Minimum. 
 
 Specific gravity at SIDA Wis Ry ain BIR eee SP anaes ea 0.943 0.9400 
 Acid number (Alcohol-Benzol)................: 8.0 eee 
 Mme 110) ONNMDET... 2... eae che sae eae 195 190 
 Unsaponifiable matter, per cent................ 0.75 ba gan 
 Peeremetive Indes. at 25° OC... . ices ccs e cee cseas 1.520 1.5165 
 Peer uinver (WijS) 2... 02k. sce cos coke ccc elelee sake 163 
 Demme tet MINUTOS, . 0... ce et ee wens cee 12 Pamels 
 
 II. METHODS OF TESTING 
 SOLUTIONS REQUIRED 
 
 2. The following reagents will be required: 
 
 Standard Sodium Thiosulfate Solution—Dissolve pure sodium thiosulfate 
 in distilled water that has been well boiled to free it from carbon dioxide in 
 the proportion so that 24.83 g. crystallized sodium thiosulfate will be present 
 in 1000 ce. of the solution. It is best to let this solution stand for about two 
 weeks before standardizing. Standardize with pure resublimed iodine. (See 
 Treadwell-Hall, Analytical Chemistry, Vol. II, third edition, p. 646.) This 
 Solution will be approximately N/10 and it is best to leave it as it is after 
 
428 Analysis of Paint Oils 
 
 determining its exact iodine value, rather than to attempt to adjust it to 
 exactly N /10 strength. Preserve in a stock bottle with a guard tube filled 
 with soda lime. 
 
 Starch Solution.—Stir up 2 to 8 g. of potato starch of 5 g. soluble starch 
 with 100 cc. of 1-per-cent salicylic acid solution, add 300 to 400 cc. boiling 
 water, and boil the mixture until the starch is practically dissolved. Dilute 
 to 1 liter. 
 
 Potassium Todide Solution.—Dissolve 150 g. of potassiuin iodide free from 
 iodate in distilled water and dilute to 1000 ce. 
 
 Iodine-Monochloride Solution.—Dissolve iodine in glacial acetic acid that 
 has a melting point of 14.7 to 15° C. and is free from reducing impurities in 
 the proportion so that 13 g. of iodine will be present in 1000 ec. of the soiu- 
 tion. The preparation of the iodine-monochloride solution presents no great 
 difficulty, but it shall be done with care and accuracy in order-to obtain satis- 
 factory results. There shall be in-the solution no sensible excess either of 
 iodine or more particularly of chlorine, over that required to form the mono- 
 chloride. This condition is most satisfactorily attained by dissolving in the 
 whole of the acetic acid to be used the requisite quantity of iodine, using A 
 gentle heat to assist the solution, if it is found necessary. Set aside a small 
 portion of this solution, while pure, and pass dry chlorine into the remainder 
 until the halogen content of the whole solution is doubled. Ordinarily it will 
 be found that by passing the chlorine into the main part of the solution until 
 the characteristic color of free iodine has just been discharged, there will be 
 a slight excess of chlorine, which is corrected by the addition of the requisite 
 amount of the unchlorinated portion until all free chlorine has been destroyed. 
 A slight excess of iodine does little or no harm, but excess of chlorine must 
 be avoided. 
 
 Chloroform.—Should be U. S, P. 
 
 Standard Sodium Hydroxide Solution.—Prepare a stock concentrated solu- 
 tion of sodium hydroxide by dissolving NaOH in water in the proportion of 
 200 g. NaOH to 200 ce. water. Allow this solution to cool and settle in a 
 stoppered bottle for several days. Decant the clear liquid from the precipi- 
 tate of sodium carbonate into another clean bottle. Add clear barium hydrox- 
 ide solution until no further precipitate forms. Again allow to settle until 
 clear. Draw off about 175 ce. and dilute to 10 liters with freshly boiled dis- 
 tilled water. Preserve in a stock bottle provided with a large guard tube 
 filled with soda lime. Determine the exact strength by titrating against pur 
 benzoic acid (C,H;COOH) using phenolphthalein as indicator. (See Bureau 
 of Standards Scientific Paper No. 183.) This solution will be approximately 
 N /4; but do not attempt to adjust it to any exact value. Determine its exact 
 strength and make proper corrections in using it. 
 
 Alcoholic Sodium Hydroxide Solution.—Dissolve pure NaOH in 95-per-cent 
 
 ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 
 
 stoppered bottle. Decant the clear liquid into another bottle, and keep well 
 stoppered. This solution should be colorless or only slightly yellow when 
 used; it will keep colorless longer if the alcohol is previously treated with 
 NaOH (about 80 g. to 1000 ec.), kept at about 50° ©. for 15 days, and then 
 distilled. For an alternate method see Journal, American Chemical Society, 
 1906,-p. 395: 
 
 ait 
 
 os ; 
 2 ee 
 ey eee ee ee ee 
 
Analysis of Paint Oils 429 
 
 Half Normal Sulfuric Acid Solution—Add about 15 ce. HoSO,4 (sp. gr. 
 1.84) to distilled water, cool and dilute to 1000 cc. Determine the exact 
 strength by titrating against freshly standardized NaOH or by any other 
 accurate method. Hither adjust to exactly N /2 strength or leave as originally 
 made, applying appropriate correction. 
 
 METHODS 
 
 3. The oil shall be tested in accordance with the following methods: 
 
 General.—The laboratory sample shall be thoroughly mixed by shaking, 
 stirring, or pouring from one vessel to another and the samples for the in- 
 dividual tests taken from this thoroughly mixed sample. 
 
 Specific Gravity.—Use a pyknometer accurately standardized and having 
 a capacity of at least 25 cc., or any other equally accurate method, making 
 the test at 15.5° C., water being 1 at 15.5° C. 
 
 Acid Number.—Weigh from 5 to 10 g. of the oil. Transfer to a 300-cc. 
 Erlenmeyer flask. Add 50 cc. of a mixture of equal parts by volume of 95- 
 per-cent ethyl alcohol and ec. p. reagent benzol. (This miature should be 
 previously titrated to a very faint pink with dilute alkali. solution, using 
 phenolphthalein as an indicator.) Add phenolphthalein indicator and titrate 
 at once to a faint permanent pink color with the standard sodium hydroxide 
 solution. Calculate the acid number (milligrams KOH per gram of oil). 
 
 Saponification Number.—Weigh about 2 g. of the oil in a 300-cce. Erlen- 
 meyer flask. Add 25 cc. alcoholic sodium hydroxfde solution. Put a con- 
 denser loop inside the neck of the flask and heat on the steam bath for one 
 hour. Cool, add phenolphthalein as indicator, and titrate with N/2 HySOq. 
 Run two blanks with the alcoholic sodium hydroxide solution. These should 
 eheck within 0.1 cc. N/2 H.SO,. From the difference between the number of 
 cubic centimeters of N /2 H.SO, required for the blank and for the determina- 
 tion, calculate the saponification number (milligrams KOH required for 
 eof the: oil). 
 
 Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
 long-neck flask. Add 5 cc. of strong solution of sodium hydroxide (equal 
 weights of NaOH and H.O), and 50 ce. 95-per-cent ethyl alcohol. Put a con- 
 denser loop inside the neck of the flask and boil for two hours. Occasionally 
 agitate the flask to break up the liquid but do not project the liquid onto the 
 sides of the flask. At the end of two hours remove the condenser and allow 
 the liquid to boil down to about 25ec. 
 
 Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
 Dilute with water to 250 cc., add 100 cc. redistilled ether. Stopper and shake 
 for one minute. Let stand until the two layers separate sharp and clear. 
 Draw all but one or two drops of the aqueous layer into a second 500-ce. 
 separatory funnel and repeat the process, using 60 ce. of ether. After thor- 
 ough separation draw off the aqueous solution into a 400-ce. beaker, then the 
 ether solution into the first separatory funnel, rinsing down with a little 
 water. Return the aqueous solution to the second separatory funnel and 
 shake out again with 60 cc. of ether in a similar manner, finally drawing the 
 aqueous solution into the beaker and rinsing the ether into the first sepera- 
 tory funnel. 
 
 Shake the combined ether solution with the accumulated water rinsings 
 and let the layers separate sharp and clear. Draw off the water and add it 
 
430 Analysis of Paint Oils 
 
 to the main aqueous solution. Shake the ether solution with two portions of 
 water (about 25 ce. each). Add these to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water down 
 to the stopcock, and draw off until the ether solution just fills the bore of 
 the stopcock. Wipe out the stem of the separatory funnel with a bit of 
 cotton on a wire. Draw the ether solution (portionwise if necessary) into a 
 250-cce. flask and distill off. While still hot, drain the flask into a small 
 weighted beaker, rinsing with a little ether. Evaporate this ether, cool and 
 weigh. 
 
 NotEe.—The unsaponifiable oil from adulterated drying oils is volatile and 
 will evaporate on long heating. Therefore heat the beaker on a warm plate, 
 occasionally blowing out with a current of dry air. Discontinue heating as. 
 soon as the odor of ether is gone. 
 
 Refractive Index.—Use a properly standardized Abbé refractometer at 25° 
 C., or any other equally accurate instrument. 
 
 Iodine Number.—Place a small quantity of the sample in a small weighing 
 burette or beaker. Weigh accurately. Transfer by dropping from 0.16 to 0.19 
 g. to a 500-cc. bottle having a well-ground glass stopper, or an Erlenmeyer 
 flask having a specially flanged neck for the iodine tests. Reweigh the 
 burette or beaker and determine the amount of sample used. Add 10 ce. of 
 chloroform. Whirl the bottle to dissolve the sample. Add 10 ec. of chloro- 
 form to each of two empty bottles like that used for the sample. Add to 
 each bottle 25 cc, of the Wijs solution and let stand with occasional shaking 
 for 380 minutes in a dark place at a temperature of from 21 to 23° CG. Add 
 10 ce. of the 15-per-cent potassium iodide solution and 100 ce. of water, and 
 titrate with standard sodium thiosulfate using starch as the indicator. The 
 titrations on the two blank tests should agree within 0.1 ec. From the dif- 
 ference between the average of the blank titration and the titration on the 
 samples and the iodine value of the. thiosulfate solution, calculate the iodine 
 number of the samples tested. (Iodine number is given in centigrams of 
 iodine to 1 g. of sample.) * 
 
 Heating Test——Test tubes containing the oil should -be 15 cm. by 16 mm., 
 with a mark near the bottom to indicate 5 ce., and closed by a cork so per- 
 forated that a glass rod 8 mm. in diameter can move freely. 
 
 Fill an 800-ce. glass beaker (height, 13 em.; diameter, 10 em.), with cotton- 
 Seed oil or soya bean oil to a height of 7.5 cm. Place a thermometer so as to 
 be 1.5 cm. from the bottom of the bath. (See Fig. 178.) 
 
 Use a nitrogen-filled, chemical thermometer; engraved stem; total length 
 4 to 4% in., graduated from 210 to 310° C. in 2° intervals; the length between 
 210 and 310° C. not less than 214 in. Thermometer glass shall be well 
 annealed. 
 
 When the bath temperature is 293° C. (560° F.) and very slowly rising 
 at this point, place the tube containing 5 ce. of the oil to be tested and the 
 tube containing 5 ce. of a control sample of known value, so that the bottom 
 of each tube is level with the lowest part of the bulb of the thermometer. 
 If desired, the collars C may be omitted and the tubes allowed to rest upon 
 
 *It is always well to include a test on a sample of tung oil of known iodine 
 value. This may be kept in a dark-colored bottle as a standard. 
 
Analysis of Paint Oils 431 
 
 oe. Sample eet po: ; 
 
 Cottonseed or : 3 
 Soya Bean _y ue ci 
 Oj] -------+°" i 2 Bae dee Soot ee 10 Cae ae 
 
 Vertical Section. 
 
 — SPECIFICATIONS — 
 A. Beaker Glass 800 cc. D. Test Tubes, IScm.x 16mm. 
 8B. Cover Plate (Iron or Wood.) E. Thermometer~ Small Range. 
 
 C. Collar Support (Rubber F. Glass Rods, (3mm. with 
 Stopper No. 6.) Cork Stoppers.) 
 
 FIGURE 178 
 
 Tung Oil Heat Test Apparatus (Revised 1920). 
 
 Nore: Collars 0 may be omitted and tubes supported in present place by 
 
 aid of wire gauze placed in bottom of oil bath and resting on bottom of beaker. 
 
432 Analysis of Paint Oils 
 
 a piece of wire gauze placed in the bottom of the oil bath so that the tubes 
 will be 1.5 cm. from the bottom of the bath. Note the time. Remove the 
 source of heat for about 45 seconds and then reapply. Before 2 minutes 
 have elapsed the temperature of the bath will have fallen to 282° C.. {5807 Pas 
 at which point it should be kept as steady as possible. When the samples 
 have been in the bath 9 minutes, raise the glass rods at intervals of 14 minute. 
 Note the time when each sample becomes firmly set. At this period the oil 
 will be so stiff that the entire tube may be lifted by aid of the rod if the 
 collar C is omitted from the apparatus. As setting or jellying takes place 
 within a few seconds of fluidity, a good end determination is afforded. 
 Remove the specimens. Heat the bath again to 293° C., and repeat the 
 experiment with fresh portions of the sample. 
 
 No stirrer is used in the bath. A sereen around the bath enables the 
 temperature to be more easily reached. When the bath oil has become tarry 
 and viscid, it should be renewed; otherwise heating may be irregular. 
 
 Quality Test*—Into an ordinary agateware casseroce, having a bottom 
 diameter of 3 in., weigh 150 ¢. of the tung oil to be tested, and set the casse- 
 role on a wide-flanged tripod having a 3-in. opening. The object of the flange 
 is to prevent super-heating of the sides of the casserole. Heat rapidly with 
 a full Bunsen flame, stirring with a thermometer, until the heat reaches 
 540° BF, (282:2° Cc.). Turn down the flame and hold the heat as near 
 540° F, (282.2° C.) as possible, stirring with the thermometer, until on lifting 
 the latter the oil drops with a pronounced string, showing that polymerization 
 has started. The time required after reaching 540° F. (282.2° C.) until the 
 string is noted, is the time of the heat test. For pure tung oils this will not 
 exceed eight minutes. As soon as the oil strings, remove the lamp and the 
 thermometer, and stir with a stiff spatula until the oil is solid. After string- 
 ing, a pure tung oil will require not over 40 seconds more to become solid. 
 When solid, allow to stand just one minute, then turn out, upside down, on 
 clean paper and cut with a clean spatula. Pure tung oil gives a gel that is 
 dry, not adhering to the spatula when cut, that is firm, crumbling under 
 pressure of the spatula without sticking, and the cut portions should crumble 
 under pressure like dry bread crumbs. Adulterated tung oil gives a gel that 
 is soft; sticky, and which will not crumble. 
 
 Ill... SAMPEING 
 The method of sampling given under Method (@) below shall be used 
 whenever it is feasible to apply it. To meet conditions when (a) is not 
 applicable, method (0) or (¢) shall be used, according to the special condi- 
 tions that obtain. 
 (a) During Loading of Tank Cars or Filling of Containers for Ship- 
 ment.— 
 . The purchaser’s inspector shall draw a sample at the .discharge pipe 
 where it enters the receiving vessel or vessels. The totai sample shall be 
 not less than 1 gal. per each tank car or 10,000 gal. equivalent, and shall be 
 a composite of small samples of not more than 1 pt. each taken at regular 
 intervals during the entire period of loading or filling. 
 
 * Furnished by R. 8S. Worstall. 
 
Analysis of Paint Oils 433 
 
 The sample thus obtained shall be thoroughly mixed, and from this com- 
 posite sample three portions of not less than 1 qt. each shall be placed in 
 clean, dry glass bottles or tin cans, which must be filled with the sample and 
 securely stoppered with new clean corks or well-fitting metal covers or cans. 
 These shall be sealed and labeled distinctly by the inspector, one delivered to 
 the buyer, one to the seller and the other held for check in case of dispute. 
 
 (b) From Loaded Tank Cars or Other Large Vessels.— 
 
 The total sample shall be not lessi than 1 gal. per each tank car or 10,000 
 gal. equivalent, and shall be a composite of numerous small samples of not 
 more than 1 pt. each., taken from the top, bottom, and intermediate points by 
 means of a glass or metal container with removable stopper or top. This 
 device attached to a suitable pole is lowered to various desired depths when 
 the stopper or top is removed and the container allowed to fill. The sample 
 thus obtained shall be handled as in Method (a). For large shipments in 
 freighters ranging from 400 to 1000 tons, first draw samples from the top 
 and bottom of both port and starboard sections of the tank. These samples 
 shall be visually examined, and if the general appearance gives indications 
 that the oil is satisfactory, pumping shall be started and 1-pt. samples drawn 
 from a bleeder in the discharge line at least once in every thirty minutes, 
 so that the total mixed sample amounts to as many gallons as there are 
 units of 10,000 gal. in the cargo. These individual samples are composited 
 to make one uniform sample representative of the “entire cargo and this is 
 handled as in Method (a). | 
 
 (ec) Barrels and Drums.— 
 
 Not less than 10 per cent of the packages in any shipment or delivery of 
 barrels and drums shall be sampled. The packages shall be shaken, rolled, 
 and stirred to thoroughly mix the contents. The samples from the individual 
 containers shall be taken through the bung hole or holes not less than 114 in. 
 in diameter bored in the head or side for the purpose. The apparatus for 
 drawing the sample shall consist of a glass tube (known as a thief) about 
 1 in. in diameter and somewhat longer than the length or diameter of the oil 
 container, a conical stopper that will fit the glass tube and is not more than 
 % in. in length, fastened to a stiff metal rod not more than 14 in. in diameter 
 and not less than 4 in. longer than the glass tube. The stopper is lowered by 
 the rod until it rests on the bottom of the cask, the tube slipped down slowly 
 over the rod, and finally pressed on the stopper. By holding the tube and the 
 rod, the column of oil can then be removed. This process is repeated until 
 the required amount of sample is obtained, which shall be not less than 1 gal. 
 This is mixed and handled as in Method (a). During the winter when the 
 oil is very often in a solid condition, the same procedure should be followed, 
 replacing the thief with a tallow trier, which is essentially a graduated piece 
 of steel tubing semi-circular in cross-section and about 3 ft. long. This is 
 pushed into the oil, turned a few times and withdrawn, thereby removing a 
 solid core of oil. 
 
 It has been found that the optical dispersion of tung oil is 
 extremely high as compared to that of many other oils. Based 
 on this, Holley has worked out a method to determine the 
 purity of tung oil (Holley, Analysis of Paint Vehicles, 1920, 
 
434 Analysis of Paint Oils 
 
 p. 81). This method, however, is not commonly in use be- 
 ae of the expense and difficulty of obtaining the type of 
 apparatus used for the purpose. It is believed, nevertheless, 
 that optical dispersion methods are of great value for the ex- 
 amination of tung oil and that they should be used when the 
 apparatus and instruments are available, as additional or 
 confirmatory tests. Asa rule, determination of specific grav- 
 ity, refractive index, and quality tests, as outlined above, 
 afford sufficient Snformatien to judge the purity and value of 
 tung’ oil. 
 
 See also quantitative method for detecting tung oil on page 
 694. 
 
 Optical Dispersion Test for Tung Oil.—As a means of 
 determining the purity of Tung Oil, optical dispersion con- 
 stants have recently become important. Considerable work 
 was done on this subject in 1912 by Potsdamer, who found that 
 it was exceedingly difficult to adulterate Tung Oil so that the 
 refractive index, specific gravity and dispersion were un- 
 changed. Apparently this method has been used quite widely 
 in China by brokers who purchase oil in quantity for export 
 to America. In the test the refractive index is ordinarily 
 determined on the D line of the sodium light. In the modern 
 Abbe refractometer, instead of sodium light, ordinary white 
 day light may be used, the achromatizer being made so as to 
 give the same reading as would be obtained with sodium 
 light. By the use of charts which accompany each instrument 
 the dispersion of an oil may be calculated. 
 
 Toch has recently given much consideration to this subject 
 and in the Third Edition of his book entitled ‘‘The Chemistry 
 and Technology of Paints’’* he presents many tables show- 
 ing the characteristics of China wood oil adulterated with 
 from 5 to 15 per cent of various other oils. In a personal 
 communication to the writer, Toch states that he has never 
 found pure Tung Oil with a refractive index less than 1.5176 
 and a dispersion value less than 0.02025—both readings at 
 21.5° C. Some of the results given by him are as follows: 
 
 Sp. Gr. Ref. Ind. Dispersion 
 
 Oil 60°F. 21.5°C. 21.5°C. 
 Chinese wood oil, \J.. M.-C... <05 ssc saree 0.938 1.5181 0.02073 
 Chinese wood oil, M. A. F.C0.. 6. 30250 sous cee 0.939 1.5183 0.02074 
 Light parafiin (Of) 06.0) < seve ye en ae ee ee 0.874 1.4870 0.01158 
 Sova, bean. OU ks. uss 8 Ss Pe ee av ee eee 0.944 1.4760 0.01027 
 Refined linseed. Olb.i'ic ccd nnn kaneis wale SU 0.933 1.4796 0.01078 
 
 *D. Van Nostrand & Co., N. Y. 
 
Analysis of Paint Oils 435 
 
 I ice ke sccs cee sesesis® (ae GiR Sattoname cate 0.940 1.4753 0.01008 
 a 0 a 0.934 1.4821 0.01062 
 EIEN ON ac e oc l6. ines sk eee vce t ys ne os 0.936 1.4822 0.01114 
 Ne eka ccs ve ce sate sceseces 0.933 1.4713 0.00971 
 I ete fo. aon ogc se oe 80 6 5 sie we ee we es 0.939 1.4816 0.01036 
 IT PUL, ccs cg tek ce sc nesceecsscees 0.913 1.4695 0.00927 
 CT We ies eels oc vn see bcc cece ces esepe 0.949 1.4860 0.01092 
 SOE a SS ee 0.922 1.4720 0.009897 
 MUP MINISERO IG Soc science isles sccascecasesese 0.914 1.4734 0.009894 
 
 TESTS ON SAMPLE I. J. M. C. CHINESE WOOD OIL 
 
 Oil Sp. Gr. Ref. Ind. Dispersion 
 
 60°F. 21,5° GC, PA Rate Bh 
 
 eevee 10% paraflin oil ......cccescccces 0.932 1.5149 0.01064 
 ee emermriMis 10% -SOya. bean: Oil.......5...... 0.938 1.5139 0.01951 
 eevee ais 1005 linseed oil .. 2... cece ese on 0.937 1.5143 0.01976 
 eee errony ete 20 PEriliqg Ol oo... 0. eee ecw eee 0.936 1.5145 0.01976 
 eens 10> COIN Oil 26... ccc tee cee 0.938 1.5140 0.01977 
 C. W. O. plus 10% menhaden oil ............... 0.938 1,5138 0.01977 
 ey eres 10S Stillingia O11 .......s.sceee0 0.937 1.5146 0.01990 
 Merwe emis 100% peanut’ Oil ........c0.0cee ees 0.938 1.5136 0.01983 
 ew ees 100, tea seed Oil...........- 00008 0.936 1.5135 0.01970 
 C. W. O. plus 10% tallow seed oil (Hankow)... 0.9438 1.5167 0.01978 
 (.W. o. plus 10% cotton seed oil.............. 0.938 1.5138 0.01962 
 oye emis 19 rape seed. oll. ..:...... 5.000 0.936 1.5139 0.01982 
 
 Solubility of Tung Oil Polymer Purity Test.—K. R. Bolton 
 and K. A. Williams have recently submitted to the writer a 
 copy of their paper which originally appeared in The Analyst. 
 This paper describes a very interesting method of differentiat- 
 ing between samples of pure and adulterated tung oil, based 
 upon the solubility of the polymer. The test as submitted is 
 given below. 
 
 The test now proposed has for its aim the separation, by 
 solvent extraction, of the adulterating oil from the mass ob- 
 tained on polymerising the oil by heat. Such separation has 
 been attempted on previous occasions by others, but seems to 
 have failed, owing to incomplete polymerisation of the tung 
 oil, due to the nature of the method used for effecting poly- 
 merisation. 
 
 Chapman* has already expressed the opinion that Wor- 
 stall’s polymerisation test, when carried out in the manner 
 originally described, is unsatisfactory, in which opinion the 
 present authors concur. It has been found, however, that the 
 following modification of Worstall’s test gives a satisfactory 
 and evenly-polymerised mass. 
 
 * Analyst 37, 453 (1912). 
 
436 Analysis of Paint Oils 
 
 Modification of Worstall’s Test—One hundred and fifty 
 orms. of the oil, contained in a stout aluminum beaker, exactly 
 3 inches in diameter and approximately 4 inches in height, are 
 heated by means of a Bunsen burner so as to reach a tempera- 
 ture of 285° C. in approximately 4 minutes, the oil being vig- 
 orously stirred by means of the thermometer during the oper- 
 ation. 
 
 As soon as the temperature of the oil has reached 285° C. 
 a stop-watch is started, and the temperature of the oil is 
 thereafter maintained as nearly as possible at 285° C., the 
 stirring being continued all the time. The time is noted when 
 polymerisation suddenly sets in, as is indicated by the failure 
 of the oil to drop from the thermometer when the latter is 
 raised from the bath. Genuine tung oils reach the stage de- 
 scribed after less than 8 minutes’ heating at 285° C. 
 
 If a long-stemmed thermometer be used, a stem correction 
 must be applied. <A variation of 3° C. from standard tempera- 
 ture throughout the polymerisation will cause a difference of 
 as much as one minute in the time of polymerisation with some 
 specimens of tung oil. 
 
 A genuine tung oil of good mercbartann quality produces a 
 dry, firm gel having a pale yellow colour and a characteristic 
 appearance and texture. 
 
 Extension of the Modification—The authors have extended 
 this modification of Worstall’s test as follows: A portion of 
 approximately 2 grms. is taken from the center of the poly- 
 merised mass and weighed into a mortar to which are added 
 about 3 grms. of dry ‘‘silver’’ sand and 2 ml. of petroleum 
 spirit. The mixture contained in the mortar is now carefully 
 incorporated with a pestle and ground until the petroleum 
 spirit has, for the most part, evaporated. The bulk of the 
 mixture is now transferred to an extractor, the mortar thor- 
 oughly washed with petroleum spirit into the extractor, and 
 the extraction carried on in the usual manner. In these 
 circumstances tung oils are found to give an extract of 28 
 per cent. with a variation not exceeding 2 per cent. on either 
 side. 
 
 A large number of different tung oils have been tested in 
 this manner, with the result that in no case did any authentic 
 sample give more than 30 per cent. of extract, provided that 
 the polymerisation had been carried out at a temperature 
 above 275° C. The fact that polymerisation is not completed, 
 by the method proposed, at lower temperatures is shown by 
 the following table: 
 
 a 
 
Analysis of Paint Oils 437 
 
 Temperature Time for polymerisation Extract 
 2c: Minutes Per Cent. 
 310 3.10 28.35 
 285, 7.25 28.25 
 268 13.50 42.20 
 250 21.75 08.10 
 
 Results with Adulterated Oils—In the case of adulterated 
 oils the whole of the adulterant is obtained in the extract, to- 
 gether with a small proportion of unpolymerised tung oil, 
 except in the case of tung oil adulterated with linseed oil, 
 which yields after polymerisation approximately half the 
 
 weight of the adulterant in the extract; this is exemplified 
 by the following table: 
 
 . Time for Theoretical* 
 Foreign Oil. Tung Oil. Polymerisation. Extract. Extract. 
 Per Cent. Per Cent. Minutes. Per Cent. Per Cent. 
 Semi-drying oil (soya) 
 0 100 7.5 29.4 29.4. 
 5 95 8.0 33.4 o chk 
 10 90 9.0 37.4 36.6 
 20 80 14.0 45.0 43.5 
 33 67 20.0 55.5 53.0 
 50 50 57.0 68.5 64.6 
 67 33 400.0 79.4 77.0 
 Tung oil acids 
 10.5 89.5 10.0 38.1 37.0 
 Linseed oil 
 0 100 Lo 29.0 29.0 
 5 95 8.0 31.4 33.0 
 10 90 8.5 83.1 36.6 
 50 50 45.0 48.4 64.6 
 
 As shown in the fourth and fifth columns of the above 
 table, the free fatty acids of tung oil do not polymerise; con- 
 Sequently, when these are present in any quantity over 2 per 
 cent., allowance must be made in computing the amount of 
 an adulterant (cf. Jameson, Analyst, 1920, 45, 328). 
 
 The proportion of adulterant present may be calculated 
 from the following formulae: 
 
 If the adulterant is not linseed oil or drying oil of high 
 iodine value: 
 
 Foreign oil per cent. = (extract per cent. — 30.0) X 1.33. 
 
 If the adulterant is linseed oil: 
 
 Foreign oil per cent. = (extract per cent. — 30.0) x 2.70. 
 
 By means of the test now proposed, in conjunction with the 
 refractive index of the original oil, it can readily be decided 
 
 *The figures in the last column are calculated on the assumption that the 
 tung oil present is polymerised to the Same extent as pure tung oil would be, 
 
 and that none of the foreign oil in the mixture is polymerised or rendered 
 insoluble in petroleum Spirit. 
 
438 Analysis of Paint Oils 
 
 whether the adulterant consists of linseed oil or not, and, in 
 most cases, a clear idea of the nature of the adulterant is 
 given. 
 
 The commercial value of tung oil presumably bears a direct 
 relationship to the amount of polymerisable matter it contains, 
 and, consequently, a test which measures this main constituent 
 and separates non-polymerisable matters must surely give a 
 better commercial valuation of the oil than any consideration 
 of ‘‘constants’’ or ‘‘variables.”’ 
 
 Accelerators for the Production of Beta Elaeostearin.—In 
 Scientific Section Circular No. 256 is given information re- 
 garding the production of beta elaeostearin from tung oil 
 through the action of light. Small percentages are induced 
 by long periods of exposure to sunlight. It is pointed out 
 in that circular that small amounts of sulphur will very rapidly 
 stimulate the production of beta elaeostearin. Some more 
 recent tests show the results obtained when from .02 per cent 
 to 5.0 per cent of ‘‘flowers’’ of sulphur are stirred into tung 
 oil and exposed to diffused hight in a room for a period of 
 from 48 hours to one week: 
 
 Percentage of Yield.after Yield after 
 No. sulphur. 48 hours 1 week 
 1 02 None 23.5% 
 2 Al None 34.5% 
 3 1.0 26% ; 39.5% 
 4 2.0 32% 45.5% 
 5 5.0 28% 49% 
 
 The results given above may be of general interest to the 
 chemist who desires to produce beta elaeostearin in substantial 
 amounts in a short period of time. 
 
 It may be of further interest to state that large deliveries of 
 tung oil to three very prominent paint and varnish manufac- 
 turers during the past year have shown the presence of very 
 substantial amounts of beta elaeostearin. In one instance, the 
 percentage was so great as to interfere with the factory utiliza- 
 tion of the product. In another instance, the oil which was 
 extremely cloudy and contained a marked amount of separated 
 crystalline matter, was used up in the factory without diffi- 
 culty. More rapid polymerization was observed in the kettle. 
 
Analysis of Paint Oils 439 
 
 In the third instance, the polymer was formed at the top of the 
 storage tank to a depth of about eight inches. Upon removal 
 of this in a sample which was subsequently exposed to hght, 
 another quantity of the polymer soon developed. Examina- 
 tion of the oil in the laboratory when received, and at a period 
 
 two months later, indicated a rise in acid value from 4.86 to 
 6.20, a rise in gravity from 0.9410 to 0.9414, a rise in refractive 
 index from 1.5185 to 1.5187, and a drop in the time of poly- 
 merization from 1114 minutes to 914 minutes. 
 
 The writer has suggested that shipments of tung oil in the 
 hulls of incoming steamers might be affected by the presence 
 of traces of sulphur in the hulls of the steamers, if they had 
 previously been used for carrying pyrites, brimstone, or simi- 
 lar cargoes containing materials which would stimulate the 
 formation of beta-elaeostearin. ‘ 
 
 F’. W. Hopkins* has referred to a shipment of approximately 
 8,000 gallons of tung oil received in the winter of 1925. The 
 tank car was heated and the oil conveyed to a storage tank 
 in a room having a temperature of approximately 85° F. Two 
 months later, a sponge-like polymer was observed at the top 
 of the tank, extending into the oil to a depth of six or eight 
 inches, while the oil in the bottom of the tank was in a sem1- 
 liquid condition. In the Browne heat test an original sam- 
 ple from the tank car showed 11% minutes, whereas a sample 
 from the bottom of the storage tank after two months’ storage 
 showed only 914 minutes. Hopkins refers to the possibility 
 of the development of changes in the oil over this period of 
 time, and found present 12.5% of beta elaeostearin. 
 
 A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
 
 SOYA BEAN OIL, RAW OR REFINED 
 
 1. PROPERTIES AND TESTS. 
 
 1. Soya bean oil, raw or refined, shall conform to the following require- 
 ments: 
 
 MAXIMUM, MINIMUM 
 TS m0 
 Loss on heating at 105 to 110° C, per cent...... 0.2 eae 
 Specific gravity at pe PG 0. he en ee ae, aye 0.924 
 SMNDTRRE e e bb ie ee ce ccs 5.0 ike 
 Bepeereation NUMbEr .. 0... keke ees cccccen. Pee 190 
 See ainer “(LIANUS) oo. s. e e e ccc nue cate. Mae 128 
 
 *“A Phenomenon to be Considered in the Purchase of China Wood Oil.” 
 Scien. Sec. Cire. 297. 
 
440 Analysis of Paint Oils 
 MAxIMUM MINIMUM 
 Unsaponifiable matter, per cemt.....-++++++eee- 1.5 i Ph 
 COlOM. ss su.ne enue an leh ae ts clapind <)s) Onl epnege kl ceeraeae Not darker than a freshly 
 
 prepared solution of 
 1.0g. potassium bichro- 
 mate in 100 cc. pure 
 H,SO, (sp. gr. 1.84). 
 
 II. METHODS OF TESTING. 
 SOLUTIONS REQUIRED. 
 
 2 The following reagents will be required : 
 
 Acetone that will pass the specification of the United States Pharmacopoeia. 
 
 Acid Calcium Chloride Solution.—Saturate with calcium chloride a mixture 
 of 90 parts water and 10 parts HCl (sp. gr. 1.18). 
 
 Standard Sodium Thiosulfate Solution.—Dissolve pure eodtas thiosulfate 
 in distilled water that has been well boiled to free it from carbon dioxide in 
 the proportion so that 24.88 g. cry stallized sodium thiosulfate will be present 
 in 1000 cc. of the solution. It is best to let this solution stand for about two 
 weeks before standardizing. Standardize with pure resublimed iodine. (See 
 Treadwell-Hall, Analytical Chemistry, Vol. I, third edition, p. 646.) This 
 solution will be approximately N/10 and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust it to 
 exactly N/10 strength. Preserve in a stock bottle with a guard tube filled 
 with soda lime. 
 
 Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. soluble starch 
 with 100 cc. of 1-per’cent salicylic acid solution, add 3800 to 400 ce. boiling 
 water, and boil the mixture until the starch is practically dissolved. Dilute 
 to 1 liter. 
 
 Potassium Iodide Sornsons —Dissolve 150 g. of PELE iodide Rie from 
 iodate in distilled water and dilute in 1000 ce. 
 
 Hanus Solution.—Dissolve 13.2 g. of iodine in 1000 ce. of glacial acetic acid 
 (99.5-per-cent) that will not reduce chromic acid. Add enough bromine to 
 double the halogen content, determined by titration (38 ce. of bromine is about 
 the proper amount). The iodine may be dissolved by the aid of heat, but the 
 solution should be cold when the bromine is added. 
 
 Standard Sodium Hydroxide Solution.—Prepare a stock concenttrated solu- 
 tion of sodium hydroxide by dissolving NaOH in water in the proportion of 
 200 g. NaOH to 200 ce. water. Allow this solution to cool and settle in a 
 stoppered bottle for several days. Decant the clear liquid from the precipitate 
 of sodium carbonate into another clean bottle. Add clear barium hydroxide 
 solution until no further precipitate forms. Again allow to settle until clear. 
 Draw off about 175 ce. and dilute to 10 liters with freshly boiled distilled water. 
 Preserve in a stock bottle provided with a large guard tube filled with soda 
 lime. Determine the exact strength by titrating against pure benzoic acid 
 (C_H_COOH) using phenolphthalein as indicator. (See Bureau of Standards 
 Scientific Paper No. 183.) This solution will be approximately N /4: but do not 
 attempt to adjust it to any exact value. Determine its exact strength and 
 make proper corrections in using it. 
 
 Alcoholic Sodium Hydroxide Solution.—Dissolve pure NaOH in 95-per-cent 
 ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a stop- 
 
 ee FGI 
 
Analysis of Paint Oils 441 
 nn ea i Ee rl 
 
 pered bottle. Decant the clear liquid into another bottle, and keep well stop- 
 pered. This solution should be colorless or only slightly yellow when used; 
 it will keep colorless longer if the alcohol is previously treated with NaOH 
 (about 80 g. to 1000 ce.), kept at about 50° G for 15 days, and then distilled. 
 For an alternate method see Journal, American Chemical Society, 1906, p. 395. 
 
 Half Normal Sulfuric Acid Solution.—Add about 15 ce. HSOq (sp. gr. 1.84) 
 to distilled water, cool and dilute to 1000 ce. Determine the exact strength 
 by titrating against freshly standardized NaOH or by any other accurate 
 method. Hither adjust to exactly N /2 strength or leave as originally made, 
 applying appropriate correction. 
 
 METHOps. 
 
 5. The oil shall be tested in accordance with the following methods: 
 
 General.—The laboratory sample shall be thoroughly mixed by shaking, 
 stirring, or pouring from one vessel to another and the samples for the indi- 
 vidual tests taken from this thoroughly mixed sample. 
 
 Loss on Heating at 105 to 110° C.—Place 10 g. of the oil in an accurately 
 weighed 200-cec. Erlenmeyer flask; weigh. Heat in an oven at a temperature 
 between 105 and 110° C. for 30 minutes; cool and weigh. Qalculate the per- 
 centage loss. This determination shall be made in a current of dry carbon 
 dioxide gas. . 
 
 Foots.—With all materials at a temperature between 20 and 27° C., mix, 
 by shaking in a stoppered flask for exactly one minute, 25 cc. of the well- 
 shaken sample of oil, 25 cc. of acetone and 10 cc. of the acid calcium chloride 
 solution. Transfer the mixture to a burette where settling can take place for 
 24 hours. The temperature during this period should be between 20 andreas ify 
 
 The volume of the stratum lying between the clear calcium chloride solu- 
 tion and the clear acetone and oil mixture is read in tenths of a cubic centi- 
 meter or a fraction thereof. This reading multiplied by four expresses the 
 amount of foots present as percentage by volume of the oil taken. 
 
 Specific Gravity—Use a pyknometer accurately standardized and having 
 a capacity of at least 25 cc., or any other equally accurate method, making the 
 test at 15.5° C., water being 1 at 15.5° C. 
 
 Acid Number.—Weigh from 5 to 10 g. of the oil. Transfer to a 300-ce. 
 Erlenmeyer flask. Add 50 cc. of neutral 95-per-cent ethyl alcohol. Put a con- 
 denser loop inside the neck of the flask. Heat on a steam bath for 30 minutes. 
 Cool and add phenolphthalein indicator. Titrate to a faint permanent pink 
 color with the standard solium hydroxide solution. Calculate the acid number 
 (milligrams KOH per gram of oil). 
 
 Saponification Number.—Weigh about 2 g. of the oil in a 300-cc. Erlen- 
 meyer fiask. Add 25 ec. alcoholic sodium hydroxide solution. Put a condenser 
 loop inside the neck of the flask and heat on the steam bath for one hour. 
 Cool, add phenolphthalein as indicator, and titrate with N /2 H,SO4. Run 
 two blanks with the alcoholic sodium hydroxide solution. These should check 
 within 0.1 cc. N/2 H2SO,4. From the difference between the number of cubic 
 centimeters of N/2 H.SO,4 required for the blank and for the determination, 
 calculate the saponification number (milligrams KOH required for 1 g. of 
 the oil). 
 
 Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
 long-neck flask. Add 5 ce. of strong solution of sodium hydroxide (equal 
 weights of NaOH and H,0), and 50 ce. 95-per-cent ethyl alcohol. Put a con- 
 
442 Analysis of Paint Oils 
 
 ee —————————t 
 
 denser loop inside the neck of the flask and boil for two hours. Occasionally 
 agitate the flask to break up the liquid, but do not project the liquid onto the 
 sides of the flask. At the end of two hours remove the condenser and allow 
 the liquid to boil down to about 25 cc. 
 
 Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
 Dilute with water to 250 cc., add 100 cc. redistilled ether. Stopper and shake 
 for one minute. Let stand until the two layers separate sharp and clear. Draw 
 all but one or two drops of the aqueous layer into a second 500-ec. separatory 
 funnel and repeat the process, using 60 cc. of ether. After thorough separation 
 draw off the aqueous solution into a 400-cc. beaker, then the ether solution 
 into the first separatory funnel, rinsing down with a little water. Return the 
 aqueous solution to the second separatory funnel and shake out again with 
 60 cc. of ether in a similar manner, finally drawing the aqueous solution into 
 the beaker and rinsing the ether into the first separatory funnel. 
 
 Shake the combined ether solution with the accumulated water rinsings and 
 let the layers separate sharp and clear. Draw off the water and add it to 
 the main aqueous solution. Shake the ether solution with two portions of 
 water (about 25 ce. each). Add these to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water down to 
 the stopcock, and draw off until the ether solution just fills the bore of the 
 stopcock. Wipe out the stem of the separatory funnel with a bit of cotton 
 on a wire. Draw the ether solution (portionwise if necessary) into a 250-ce. 
 flask and distill off. While still hot, drain the flask into a small weighed 
 beaker, rinsing with a little ether. Evaporate this ether, cool and weigh. 
 
 Note.—The unsaponifiable oil from adulterated drying oils is volatile and 
 will evaporate on long heating. Therefore heat the beaker on a warm plate, 
 occasionally blowing out with a current of dry air. Discontinue heating as 
 soon as the odor of ether is gone. 
 
 Hanus Iodine Number.—Place a small quantity of the sample in a small 
 weighing burette or beaker. Weigh accurately. Transfer by dropping about 
 0.15 g. (0.10 to 0.20 g.) to a 500-cce. bottle having a well-ground glass stopper, 
 or an Erlenmeyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine the amount of sample used. 
 Add 10 ce. of chloroform. Whirl the bottle to dissolve the sample. Add 
 10 cc. of chloroform to each of two empty bottles like that used for the sample. 
 Add to each bottle 25 ce. of the Hanus solution and let stand with occasional 
 shaking for one-half hour. Add 10 ce. of the 15-per-cent potassium iodide 
 solution and 100 cc. of water, and titrate with standard sodium thiosulfate, 
 using starch as indicator. The titrations on the two blank tests should agree 
 within 0.1 ce. From the difference between the average of the blank titration 
 and the titration on the samples and the iodine value of the thiosulfate solu- 
 tion, calculate the iodine number of the samples tested. (Iodine number is 
 centigrams of iodine to 1 g. of sample.) 
 
 Color——Prepare a fresh solution of pure potassium bichromate in pure 
 colorless H,SO,4 (sp. gr. 1.84). This solution should be in the proportion of 
 1.0 g. potassium bichromate to 100 ce. (184.0 g.) H,SO,. Place the oi] and 
 colored solution in separate thin-walled, clear glass tubes of the same diameter 
 (1 to 2 cm.) to a depth of not less than 2.5 cm. and compare the depths of color 
 by looking transversely through the columns of liquid by transmitted light. 
 
 a 
 
Analysis of Paint Oils 443 
 
 A. 8S. T. M. STANDARD SPECIFICATIONS FOR 
 
 PERILLA OIL, RAW OR REFINED 
 
 I. PROPERTIES AND TESTS. 
 1. Perilla oil, raw or refined, shall conform to the following requirements: 
 
 RICO GG rire stk sce cece sess ceensence 2.5 
 
 Loss on heating at 105 to 110° C., per cent...... 0.2 at 
 Meeeeuceeravity at 15.5° /15.5° C....... eee “rat 0.932 
 NM Es yee Gio k pole vcvesecs'eoeeseeedes 5.0 ee 
 em estION HUMPCL 2.2... ec cc tect ce acees “ae 190 
 Sepmeriiper (HANUS)... 0... ccc tc wesc cece as 191 
 Unsaponifiable matter, per cent................ Lb c. 
 JO CEE eee Gicieke o-vity « oes. 0 5 
 
 Not darker than a freshly 
 prepared solution of 
 1.0 g. potassium bichro- 
 mate in 100 ce. pure 
 H.SO,4 (sp. gr. 1.84). 
 
 II. METHODS OF TESTING. 
 SOLUTIONS REQUIRED. ; 
 
 2. The following reagents will be required: 
 
 Acetone that will pass the specifications of the United States Pharma- 
 copoeia. 
 
 Acid Calcium Chloride Solution.—Saturate with calcium chloride a mix- 
 ture of 90 parts water and 10 parts HCl (sp. gr. 1.19). 
 
 Standard Sodium Thiosulfate Solution.—Dissolve pure sodium thiosulfate 
 in distilled water that has been well boiled to free it from carbon dioxide in 
 the proportion so that 24.83 g. crystallized sodium thiosulfate will be present 
 in 1000 ce. of the solution. It is best to let this solution stand for about two 
 weeks before standardizing. Standardize with pure resublimed iodine. (See 
 Treadwell-Hall, Analytical Chemistry, Vol. II, third edition, p. 646.) This 
 solution will be approximately 0.1 N and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust it to 
 exactly 0.1 N strength. Preserve in a stock bottle with a guard tube filled 
 with soda lime. 
 
 Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. soluble starch 
 with 100 ce. of 1-per-cent salicylic acid solution, add 800 to 400 ce. boiling 
 water, and boil the mixture until the starch is practically dissolved. Dilute 
 to 1 liter. 
 
 Potassium Iodide Solution.—Dissolve 150 g. of potassium iodide free from 
 iodate in distilled water and dilute to 1000 cc. 
 
 Hanus Solution.—Dissolve 13.2 g. of iodine in 1000 ce. of glacial acetic acid 
 (99.5-per-cent) that will not reduce chromic acid. Add enough bromine to 
 double the halogen content, determined by titration (3 cc. of bromine is 
 about the proper amount). The iodine may be dissolved by the aid of heat, 
 but the solution should be cold when the bromine is added. 
 
 Standard Sodium Hydroxide Solution—Prepare a stock concentrated 
 solution of sodium hydroxide by dissolving NaOH in water in the proportion 
 of 200 g. of NaOH to 200 ce. of water. Allow this solution to cool and settle 
 in a stoppered bottle for several days. Decant the clear liquid from the 
 precipitate of sodium carbonate into another clean bottle. Add clear barium 
 
444 Analysis of Paint Oils 
 
 hydroxide solution until no further precipitate forms. Again allow to settle 
 
 until clear. Draw off about 175 cc. and dilute to 10 liters with freshly boiled. 
 
 distilled water. Preserve in a stock bottle provided with a large guard tube 
 filled with soda lime. Determine the exact strength by titrating against pure 
 benzoic acid (CgH; COOH) using phenolphthalein as indicator. (See Bureau 
 of Standards Scientific Paper No. 183.) This solution will be approximately 
 0.25 N, but do not attempt to adjust it to any exact value. Determine its 
 exact strength and make proper corrections in using it. 
 
 Alcoholic Sodium Hydroxide Solution—Dissolve pure NaOH in 95-per-cenr 
 ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 
 stoppered bottle. Decant the clear liquid into another bottle, and keep well 
 stoppered. This solution should be colorless or only slightly yellow when 
 used; it will keep colorless longer if the alcohol is previously treated with 
 NaOH (about 80 g. to 1000 cc.), kept at about 50° C. for 15 days, and then 
 distilled. For an alternate method see Journal, American Chemical Society, 
 1906, p. 395. 
 
 Half Normal Sulfuric Acid Solution—Add about 15 cc. HeSO, (sp. gr. 
 1.84) to distilled water, cool and dilute to 1000 ec. Determine the exact 
 strength by titrating against freshly standardized NaOH or by any other 
 accurate method. Either adjust to exactly 0.5 N strength or leave as origi- 
 nally made, applying appropriate correction, 
 
 METHODS. 
 
 2 The oil shall be tested in accordance with the following methods: 
 
 General_—The laboratory sample shall be thoroughly mixed by shaking, 
 stirring, or pouring from one vessel to another and the samples for the 
 individual tests taken from this thoroughly mixed sample. 
 
 Loss on Heating at 105 to 110° C.—Place 10 g. of the oil in an accurately 
 weighed 200-cc. Erlenmeyer flask; weigh. Heat in an oven at a temperature 
 between 105 and 110° C. for 30 minutes; cool and weigh. Calculate the per- 
 centage loss. This determination shall be made in a current of dry carbon 
 dioxide gas. 
 
 Foots.—With all materials at a temperature between 20 and 27° C., mix, 
 by shaking in a stoppered flask for exactly one minute, 25 cc. of the well- 
 shaken sample of oil, 25 ec. of acetone and 10 ce. of the acid calcium chloride 
 solution. Transfer the mixture to a burette where settling can take place 
 for 24 hours. The temperature during this period should be between 20 and 
 Pg eae &? 
 
 The volume of the stratum lying between the clear calcium chloride solu- 
 tion and the clear acetone and oil mixture is read in tenths of a cubic cen- 
 timeter or a fraction thereof. This reading multiplied by four expresses the 
 amount of foots present as percentage by volume of the oil taken. 
 
 Specific Gravity—Use a pyknometer accurately standardized and haying 
 a capacity of at least 25 cc., or any ier ee) accurate method, making 
 the test at 15.5° C., water Haine 1 at 165° 6, 
 
 Acid Number.-—Weigh from 5 to 10 g. of the oil. Transfer to a 300-ce. 
 Erlenmeyer flask. Add 50 ce. of neutral 95-per-cent ethyi alcohol. Put a 
 condenser loop inside the neck of the flask. Heat on a steam bath for 30 
 minutes. Cool and add phenolphthalein indicator. Titrate to a faint per- 
 manent pink color with the standard sodium hydroxide solution. Calculate 
 the acid number (milligrams of KOH for 1 g. of the oil). 
 
 ee ee ee ee eS 
 
Analysis of Paint Oils 445 
 
 Saponification Number.—Weigh about 2 g. of the oil in a 300-ce. Erlen- 
 meyer flask. Add 25 ce. of alcoholic sodium hydroxide solution. Put a con 
 denser loop inside the neck of the flask and heat on the steam bath for one 
 hour. Cool, add phenolphthalein as indicator, and titrate with 0.5 N H»)SOx4. 
 Run two blanks with the alcoholic sodium hydroxide solution. These should 
 check within 0.1 cc. of 0.56 N H.SO4. From the difference between the num- 
 ber of cubic centimeters of 0.5 N HoSO,4 required for the blank and for the 
 determination, calculate the saponification number (milligrams of KOH 
 required for 1 g. of the oil). : 
 
 Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
 long-neck flask. Add 5 ce. of strong solution of sodium hydroxide (equal 
 weights of NaOH and H,O), and 50 cc. of 95-per-cent ethyl alcohol. Put a 
 condenser loop inside the neck of the flask and boil for two hours. Occa- 
 sionally agitate the flask to break up the liquid but do not project the liquid 
 onto the sides of the flask. At the end of two hours remove the condenser and 
 allow the liquid to boil down to about 25 ce. 
 
 Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
 Dilute with water to 250 cc., add 100 cc. of redistilled ether. Stopper and 
 shake for one minute. Let stand until the two layers separate sharp and 
 clear. Draw all but one or two drops of the aqueous layer into a second 
 500-ce. separatory funnel and repeat the process using 60 cc. of ether. After 
 thorough separation draw off the aqueous solution into a 400-cc. beaker, 
 then the ether solution into the first separatory funnel, rinsing down with a 
 little water. Return the aqueous solution to the second separatory funnel and 
 shake out again with 60 cc. of ether in a similar manner, finally drawing the 
 aqueous solution into the beaker and rinsing the ether into the first separa- 
 tory funnel. 
 
 Shake the combined ether solution with the accumulated water rinsings 
 and let the layers separate sharp and clear. Draw off the water and add it 
 to the main aqueous solution. Shake the ether solution with two portions of 
 water (about 25 cc. each). Add these to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water down 
 to the stopcock, and draw off until the ether solution just fills the bore of the 
 stopcock. Wipe out the stem of the separatory funnel with a bit of cotton 
 on a wire. Draw the ether solution (portionwise if necessary) into a 250-cc. 
 - flask and distill off. While still hot, drain the flask into a small weighed 
 beaker, rinsing with a little ether. Evaporate this ether, cool and weigh. 
 
 Note.—The unsaponifiable oil from adulterated drying oils is volatile and 
 will evaporate on long heating. Therefore heat the beaker on a warm plate, 
 occasionally blowing out with a current of dry air. Discontinue heating as 
 soon as the odor of ether is gone. 
 
 Hanus Iodine Number.—Place a small quantity of the sample in a small 
 weighing burette or beaker. Weigh accurately. Transfer by dropping about 
 0.15 g. (0.10 to 0.20 g.) to a 500-ce. bottle having a well-ground glass stopper, 
 or an Erlenmeyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine the amount of sample used. 
 Add 10 ce. of chloroform. Whirl the bottle to dissolve the sample. Add 10 
 ec. of chloroform to each of two empty bottles like that used for the sample. 
 Add to each bottle 25 cc. of the Hanus solution and let stand with occasional 
 shaking for 30 minutes. Add 10 ce. of the 15-per-cent potassium iodide solu- 
 
446 Analysis of Paint Oils 
 
 ae 
 
 tion and 100 ec. of water, and titrate with standard sodium thiosulfate using 
 starch as indicator. The titrations on the two blank tests should agree within 
 0.1 ec. From the difference between the average of the blank titration and 
 the titration on the samples and the iodine value of the thiosulfate solution, 
 caleulate the iodine number of the samples tested. (lodine number is centi- 
 grams of iodine to 1 g. of sample.) 
 
 Color.—Prepare a fresh solution of pure potassium bichromate in puré 
 colorless HySO,4 (sp. gr. 1.84). This solution should be in the proportion of 
 1.0 g. of potassium bichromate to 100 cc. (184.0 g.) of H.SO4. Place the oil 
 and colored solution in separate thin-walled, clear glass tubes of the same 
 diameter (1 to 2 cm.) to a depth of not less than 2.5 cm. and compare the 
 depths of color by looking transversely through the columns of liquid by 
 transmitted light. 
 
CHAPTER XXIV 
 
 ANALYSIS OF VARNISH 
 
 The testing of oleo-resinous varnish should largely be of a 
 physical nature. Such properties as odor, consistency, clarity, 
 flowing, time of drying, character of finish, hardness, resist- 
 ance to moisture and abrasion, elasticity, etc., point out the 
 real value of a varnish. Chemical tests that give additional 
 information, sometimes of value, are as follows: Acid num- 
 ber, ash, character of solvent, fixed oil and resins. 
 
 Acid Number.—Ten to 20 grams of the varnish are weighed 
 in a small Erlenmeyer flask, 50 ce. neutral aleohol added, and 
 a small funnel inserted in the neck. Heat on the water bath 
 
 —————— 
 
 . = ee 3 
 WW 
 
 FIGURE 179 
 
 Apparatus for determining gas resistance of varnish. See Federal Specifi- 
 cations Board Specifications, back of volume. 
 
448 Anal ysis of Varnish 
 
 for one-half hour, with occasional shaking. Allow to cool 
 somewhat, add two drops of phenolphthalein indicator and 
 titrate with tenth-normal potassium hydroxide solution. The 
 acid number is the number of milligrams of KOH required to 
 neutralize each gram of the varnish. Use of a mixture of 
 equal volumes of alcohol and benzol 90° gives the true acid 
 number of a varnish including colloidal acidity that would not 
 be indicated by alcohol alone. (See page 465.) 
 
 Ash-—Weigh in a porcelain or fused silicia crucible several 
 grams of the varnish. Burn off over a small Bunsen flame, 
 using great caution to avoid boiling over and spattering. 
 When at combustible matter is destroyed, weigh the ash and if 
 desired analyze it. 
 
 Solvent.—Steam distillation of a portion of the varnish will 
 remove the solvents, leaving a residue of fixed oils and varnish 
 resins, which may be weighed after driving off the water. The 
 distillate should be examined as recommended under Turpen- 
 
 FIGURE 180 
 
 Apparatus for determining draft resistance of varnish. See Federal Specifi- 
 cations Board Specifications, back of volume. 
 
 tine Specifications. The amount of mineral spirits and turpen- 
 tine may thus be determined. 
 
 It is customary to conduct the steam distillation upon 90 
 grams of varnish in a 500-ce. Erlenmeyer flask placed in an oil 
 bath maintained at about 130° F. The distillate may be col- 
 lected in a separatory funnel. The water may then be drawn 
 off and the distillate examined. 
 
 A much more rapid and fully as accurate a method for de- 
 termining the percentage of volatile is as follows. This 
 method, however, does not yield the actual volatile for subse- 
 quent examination. 2 
 
Analysis of Varnish 449 
 
 Percentage of Volatile-—Place a portion of the sample in a 
 stoppered bottle. Weigh the container and sample. Transfer 
 about 1.5 grams of the sample to a flat bottom metal dish about 
 8 cm. in diameter (a friction top can plug). Weigh the bottle 
 again and by difference calculate the exact weight of the por- 
 tion of the sample transferred to the metal dish. Heat the 
 dish and contents in an oven maintained at 105° to 110° C. for 3 
 hours. Cool and weigh. From the weight of the residue left 
 in the dish and the weight of the sample taken, calculate the 
 percentage of non-volatile residue. 
 
 Fixed Oils and Resins.—In the above determination, the 
 total amount of fixed oils and resins is obtained. It is a diffi- 
 cult matter, however, to determine the exact percentage and 
 character of resins that have been used in the manufacture 
 of the varnish. This is due to the fact that during the process 
 of heating oils in the presence of resins many intricate chem- 
 ical changes are brought about, a considerable portion of the 
 resins being distilled off in the form of vapors and combina- 
 tions of the oil brought about that are difficult of separation. 
 One of the best methods, however, of separating the fixed oils 
 and varnish resins is carried out in the following manner: 
 
 A portion of about a half ounce of the varnish resin should 
 be placed in a 300-ce. tared beaker. There should then be 
 added about 200 ce. of ice-cold petroleum ether. After stir- 
 ring the beaker should be covered and allowed to stand, prefer- 
 ably in a dish containing ice. In an hour’s time the resinous 
 ingredients will be found precipitated at the bottom of the 
 beaker or adhering to the side thereof (with the exception of 
 rosin, which is largely soluble in petroleum ether). The pre- 
 cipitated resins should be washed with fresh portions of cold 
 petroleum ether two or three times, pouring the decanted por- 
 tions into a large bottle. The combined portions of petroleum 
 ether may then be filtered through a tared filter, adding by the 
 aid of a stirring rod the resins contained in the beaker. The 
 filter paper and the beaker with the resins may then be dried 
 at 100° C. and weighed. The combined filtrates may be dis- 
 tilled to obtain the fixed oil as a residue, which may be ex- 
 amined for constants. (This fixed oil may contain rosin.) 
 The amount of rosin contained in a varnish may be roughly 
 ascertained by thoroughly shaking in a separatory funnel a 
 portion of the varnish with a large quantity of absolute alco- 
 
450 Analysis of Varnish 
 
 hol. The rosin may be obtained by evaporation of the alco- 
 holic extracts. The fixed oils after oxidation or polymeriza- 
 tion, as caused by the heating of the varnish during manufac- 
 ture, are not readily soluble in alcohol. 
 
 Separation of Polymerized Oils and Resins.—In the making 
 of varnish, most oils become oxidized or polymerized to a con- 
 dition resembling resins. For instance, when a varnish is ex- 
 amined for resins by the above method, it will often be found 
 that a considerable amount of matter insoluble in pertroleum 
 ether will be obtained even when hard resins are absent. The 
 insoluble substance is oxidized or polymerized oil. It may be 
 differentiated from varnish resins by the fact that it may be 
 saponified by alcoholic potash. | 
 
 This method, as used by the regulatory division of the State 
 of North Dakota, is the original method published by HE. W. 
 Boughton of the Bureau of Standards (see U.S. Bureau of 
 Standards Technologic Bulletin 65), as modified in North Da- 
 kota. Although it involves a tremendous amount of work, it is 
 probably the most accurate method for the separation of 
 polymerized oils and resins. The method follows Boughton’s 
 original scheme very closely. The use, however, of ice-cold 
 ether and ice-cold water is probably an advantage in that the 
 ether separations are quicker and sharper. In Boughton’s orig- 
 inal method, the material extracted by ether from the first 
 saponification mixture of acids and fatty acid soaps 1s termed 
 unsaponifiable matter. In the North Dakota revision, the pro- 
 posal is made to add this same ether extract to the resin por- 
 tion. This constitutes a somewhat radical difference between 
 the two schemes and clearly brings out the fact that neither 
 Boughton’s method nor the North Dakota method can be relied 
 upon to give the true oil content of present-day varnishes. For 
 instance, at least one of the varnishes on the. market today 
 contains wool fat (degras). In Boughton’s method this 
 product would show up as unsaponifiable matter, while im the 
 North Dakota method the unsaponifiable part of the wool fat 
 would be included in the resins. This same difference would 
 be true of a varnish containing paraffin. On the other hand, 
 a varnish made of tung oil and cumarin resin would show a 
 high unsaponifiable and resin content by Boughton’s method, 
 while the North Dakota method would indicate the cumarin as 
 resin. 3 
 
Analysis of Varnish 451 
 
 In view of the above, it is quite apparent that neither one of 
 these methods should be included as a part of any routine 
 method of analysis of a varnish but should be merely classed 
 as “‘stunt’’ tests for a research laboratory, where an insight 
 into the ingredients of a varnish is desired. All of which 
 brings out the absolute futility of a varnish analysis as a basis 
 of evaluation. Physical tests afford the only reliable data in 
 judging the properties of an oleo-resinous varnish. 
 
 Method.—Weigh by difference from 4 to 6 grams of the 
 varnish into a 125-cc. Erlenmeyer flask, add 25 ce. of water and 
 boil gently until not over 5 ce. of water is left. This is best 
 performed by placing the flask in an oil bath, and by passing a 
 stream of carbon dioxide through the mixture during the evap- 
 
 oration. Then add 25 ce. each of half normal alcoholic potash 
 and benzol, and reflux for one hour. 
 
 Evaporate the solution down to about 10 ce. and transfer to 
 a 900-ec. globe-shaped separatory funnel, rinsing the flask well 
 with water, alcohol and ether. Add 100 cc. each of water and 
 ethyl ether and shake well, using a moderate circular motion. 
 In this and all similar operations use ice-cold ether and ice- 
 cold water. The shaking should be repeated three times. 
 Should an emulsion ‘eank and not break within five minutes, 
 add 2 ce. of alcohol. 
 
 Draw off the aqueous layer into another separatory funnel 
 and wash the ether layer twice with cold water. Add the wash- 
 ings to the aqueous layer and transfer the ether layer to a 
 weighed Erlenmeyer flask labeled ‘‘Gums.’’ Acidify the aque- 
 ous layer and completely extract with ether. Transfer the 
 ether solution to the Erlenmeyer flask into which the varnish 
 was weighed and distill off the solvent, using a vertical con- 
 denser. Then add 10 ce. absolute alcohol and evaporate on a 
 steam bath. This is to remove the water present. Distill off 
 the solvent in the ‘‘Gums’’ flask whenever the flask becomes 
 half-full. All ether solutions of unsaponifiable matters and 
 the resins acids that are separated out from subsequent ex- 
 tractions are transferred to this flask. 
 
 To the residue extracted from the acid solution add 20 ee. 
 of absolute alcohol and 20 ce. of a mixture of 4 parts of 
 absolute alcohol and 1 part of concentrated sulphuric acid. 
 Reflux for five minutes, transfer to a separatory funnel, rins- 
 ing the flask with meter and ether, add 100 ee. of amen 
 
452 Analysis of Varnish 
 
 Shake well, add 100 cc. of a 10-per-cent solution of sodium 
 chloride, and shake several times. Draw off the aqueous 
 layer and extract with 50 ce. of ether. Wash the combined 
 ether layer and discard the aqueous layers. ‘To the ether 
 layer add 50 ce. fifth normal aqueous potassium hydroxide 
 and 10 ec. of aleohol and shake well, using a moderate circu- 
 lar motion. Repeat the shaking as soon as the layers have 
 separated. Separate the layers and wash the ether layer with 
 50 ec. of water containing 5 ec. of the aqueous potassium 
 hydroxide and 5 ce. of alcohol. 
 
 Combine the aqueuos layers and extract with ether keep- 
 ing all insoluble soaps with the ether layer. Then combine 
 the ether layers, transfer to an Erlenmeyer flask, and distill 
 off the solvent. Take the aqueous layers, acidify with hydro- 
 chloric acid and extract completely with ether. Transfer this 
 ether solution to the ‘‘Gums”’ flask. ‘ 
 
 Take the residue and reflux with 25 ec. of alcoholic potash 
 for one hour. Evaporate on steam bath until only 10 ce. re- 
 mains. Cool, transfer to a separatory funnel with the aid 
 of 50 ec. each water and ether and shake. Use the same 
 moderate circular motion. Repeat the shaking twice and 
 draw off the aqueous layer. Extract the aqueous layer with 
 ether again. Combine the ether layers and wash twice with 
 600 ec. portions of water. Transfer the ether layers to the 
 ‘‘Gums’’ flask. Take the aqueous layer and the washings 
 from the ether layer, acidify with hydrochloric acid and ex- 
 tract completely with ether. Transfer these ether extracts to 
 a weighed Erlenmeyer flask, distill off the solvent and heat 
 on a steam bath with small portions of absolute alcohol until 
 all of the water is removed. Then heat to constant weight 
 at 105° C., in an oven filled with carbon dioxide. Weigh as 
 fatty acids. 
 
 Take the ‘‘Gums”’ flask, distill off the solvent, remove the 
 water, dry and weigh as in the case of the fatty acids. This 
 weight is reported as resins or as varnish gums. 
 
 Calculations: 
 
 Wt. of Resins < 1.07 
 (a) ———__—_ 
 
 < 100 = percent total of resins (direct). 
 Wt. of sample 
 
Analysis of Varnish 453 
 
 Wt. of fatty acids 
 ee —— < 100 — per cent of total oils. 
 Wt of sample 
 
 (c) (Per cent of non-volatile—per cent of ash) = per cent of total resins 
 (by difference). 
 
 A method of examining the fatty acids separated from the 
 resins in a varnish, as described by de Waele* and by Wolff,+ 
 is referred to on page 329 of the very valuable book entitled 
 ‘Varnishes and Their Components,’’ by R. S. Morrell (Ox- 
 ford Technical Publications). The reader is referred to the 
 original papers for a detailed study of the methods. It is 
 beheved that while occasion may arise for work of this char- 
 acter, as a rule much more information regarding the suit- 
 ability of a varnish for a certain purpose can be obtained 
 by practical physical tests, as referred to in other sections 
 of this volume. P 
 
 Tung Oil Detection.—F or ascertaining the presence of tung 
 oil in the non-volatile portion of a varnish, see test on page 694. 
 
 EXAMINATION OF Sprrit VARNISHES 
 
 Distillation of 100 ec. may be made when it is important to 
 determine the type of solvents used. The distillate can be 
 fractioned and tested for alcohol, benzol, or similar light sol- 
 vents generally employed in such varnishes. Mineral spirits 
 and turpentine are to be looked for when spirit varnishes of 
 the dammar type are believed present. The solvents used 
 in shellac varnish and shellac varnish substitutes, Manilla, 
 Rosin, ete., are generally of the alcohol soluble type. 
 
 For a determination of the amount of solvent present in a 
 spirit varnish, a quantity can be weighed out in a friction top 
 tin cover, evaporated in an oven, and the residue weighed as 
 described elsewhere in this volume for the determination of 
 the amount volatile matter in varnishes. The residue left 
 from the evaporation may be examined to secure some in- 
 formation regarding the type of resin used. Determination 
 of the solubility of the residue in various solvents, determina- 
 tion of the acid value, and similar characteristics, as out- 
 
 *de Waele, Journ. Oil Col. Chem. Assoc., 1920, a Kat iy 
 1H. Wolff, Chem. Age, 1921, 15, 2989. 
 
454 Analysis of Varnish 
 
 ——— 
 
 lined under the chapter for the examination of resin, may 
 afford considerable information. 
 
 Morrell, in commenting upon a scheme for the detection 
 and separation of common resins, as published by H. Rebs 
 in ‘‘Die Spirituslackfabrikation’’ (1905), makes the follow- 
 ing statement: | 
 
 ‘‘Concentrated acetic acid will dissolve lac, rosin, an oleo- 
 resin of turpentine and accroides resin. Very dilute ammonium 
 chloride will dissolve lac, while manila, sandarach, rosin, 
 and accroides are insoluble. Benzine (light petroleum) will 
 dissolve rosin or an oleoresin, but manila, sandarach, lac, 
 and accroides are insoluble in that solvent. In order to 
 separate the different resins qualitatively and quantitatively 
 in a spirit varnish, the solvent is distilled off, the residue 
 is finely powdered and warmed on the water bath with the 
 solvents mentioned above. If lac and rosin be present, the 
 lac will dissolve in very dilute ammonium chloride. Lac 
 may be separated from manila or sandarach, and likewise 
 from rosin, but the separation of sandarach from manila 
 copal is very doubtful. The estimation of dammar admixed 
 with spirit copal or kauri by means of alcohol and chloro- 
 form has been put forward by Stewart.* ‘The resin is boiled 
 with alcohol, which dissolves the spirit copal and part of the 
 dammar. The residue is extracted with chloroform in a Soxh- 
 let, whereby the remainder of the dammar is dissolved. The 
 amount of the chloroform-soluble extract is a measure of the 
 percentage of dammar. The insolubility of a genuine sam- 
 ple of the particular variety of dammar must be known. 
 
 ‘‘Tt is evident that the methods of separation of the indi- 
 vidual resins in a mixture are by no means satisfactory, and 
 there is need for much investigation in that field.j At pres- 
 ent the works tests are essentially the most reliable. Elastic- 
 ity, lustre, hardness, uniformity of film, and, in the case 
 
 of coloured spirit varnishes, stability to heat and light, are 
 
 compared against special requirements. On metals the var- 
 nish film must be clean and the coating must not have an acid- 
 ity likely to set up chemical interaction with the metals. De- 
 termination of acidity, behaviour on drying, flow, colour, and 
 
 specific gravity are compared with corresponding values of. 
 
 the standard sample. 
 
 *S. Stewart, Journ. Soc. Chem. Ind., 1909, 28, 348. 
 + Dietrich, Analysis of Resins, 2nd Ed. 
 
 ee ee ee ee ee | 
 
Analysis of Varnish 455 
 
 “Tf the spirit varnish contain nitrocellulose celluloid, or 
 cellulose acetate, the residue after the removal of the sol- 
 vents must be examined by special tests. Treatment with 
 a dilute solution of diphenylamine in concentrated sulphuric 
 acid Will give a blue coloration in the presence of nitrocellulose. 
 Nitrocellulose may be estimated in the residue by measuring 
 the volume of nitric oxide evolved by the action of ferrous 
 chloride and hydrochloric acid at 100° C., whereby the nitro- 
 group of the nitrocellulose is reduced to nitric oxide. 
 
 ‘‘Celluloid may be detected by the identification of the 
 incorporated camphor, which can be removed by ether or by 
 methyl alcohol, in which the nitrocellulose is insoluble. 
 
 ‘‘Hor the detection of cellulose acetate, gentle heating with 
 concentrated sulphuric acid and a little alcohol will give 
 amyl acetate. 
 
 ‘‘Mor the identification of the cellulose componént original 
 residue may be boiled with hydrochloric acid (sg. 1.10), 
 neutralised, and tested for the sugars with TFehling’s 
 solution. The cellulose in nitrocellulose and celluloid can 
 likewise be detected by the production of reducing sugars on 
 hydrolysis.’’—For methods of testing shellac varnishes see 
 Chapter X XIX. 
 
 A. 8. T. M. STANDARD METHODS OF TESTING | 
 OLEO-RESINOUS VARNISHES 
 
 1. (a) All tests shall be made at room temperature between 21 and 
 32° ©. (70 and 90° F.). 
 
 (b) All tests shall be made in diffused light (not in direct sunlight). 
 
 (c) When a can of varnish has been opened and part of its contents has 
 been used, the remainder shall immediately be placed in air-tight containers 
 which the varnish entirely fills, leaving not more than 2 per cent of .air 
 space. ies 
 (d) The tin panels used shall be cut from bright tinplate weighing not 
 more than 25 g. nor less than 19 g. per square decimeter (0.51 to 0.39 Ib. 
 per sq.ft. ). 
 
 NoTE.—Commercial No. 31 gage bright tinplate should weigh about 0.44 
 lb. per sq. ft. 
 
 It is important that the tinplate shall be within the limits prescribed. 
 The panel shall be about 7.5 by 13 em. (3 by 5 in.) and shall be thoroughly 
 cleaned with benzol immediately before using. 
 
 Norte.—It is important that the rags used in wiping the panels are clean. 
 
456 Analysis of Varnish 
 
 Ee 
 
 I. APPEARANCE 
 29. Some of the thoroughly mixed sample shall be poured into a clear 
 glass bottle or test tube, 1.5 to 2.0 em. (% to 134, in.) in diameter to a depth 
 of at least 2.5 em. The varnish shall then be examined by transmitted light 
 and shall be clear and transparent. 
 
 II. COLOR 
 
 3. (a) Standard color solutions shall be prepared by dissolving 1, 2, 3, 
 4, 5 and 6 g., respectively, of pure powdered potassium bichromate in 100 ce. 
 of pure concentrated HjSO4 (sp. gr. 1.84). Gentle heat may be applied, if 
 necessary, to effect the solution of bichromate. 
 
 (b) The standard color solutions and a sample of the varnish to be tested 
 shall be poured into thin-walled glass tubes 1.5 to 2.0 em. (5% to 1%. in.) in 
 diameter to a depth of at least 2.5 em. The color comparison shall be made by 
 placing the tubes close together and looking through them by transmitted light. 
 
 Since the potassium bichromate-sulfurie acid solution must be freshly 
 made for this color comparison, it is frequently more convenient to compare 
 samples with a series of permanently sealed tubes of varnish which have 
 been previously found to be lighter in color than the standard solutions. When 
 a sample is found to be darker than a standard tube of varnish, the bichromate 
 standard should be made up for final decision. The color of the varnish shall 
 be stated in terms of the standard (calling the standards No. 1, No. 2, No. 3, 
 ete.) with which it is equal or lighter than. 
 
 Nore.—Stabilized caramel solutions or other permanent colored liquids 
 may be used as secondary standards. 
 
 III. NON-VOLATILE MATTER 
 
 4. A portion of the sample of the varnish shall be poured into a stoppered 
 bottle or weighing pipette and weighed. About 1.5 g. of the sample shall be 
 transferred to a flat-bottomed metal dish about 8 cm. in diameter. (Note.— 
 A friction-top can plug is satisfactory.) The container shall be weighed again, 
 and the exact weight of the portion of the sample transferred to the weighed 
 dish shall be calculated by difference. The dish with its contents shall be 
 heated for 3 hours in an oven maintained at 105 to 110° C. (221 to 230° F.). 
 It shall then be weighed after cooling. 
 
 5. The ratio of the weight of the residue to that of the sample, expressed 
 as a percentage, shall be taken as the percentage of non-volatile matter in the 
 varnish. 
 
 IV. TEST FOR ELASTICITY OR TOUGHNESS 
 
 6. The elasticity or toughness of the varnish shall be determined by pro- 
 portionately reducing its elasticity or toughness by the addition of a standard 
 solution of Rum Kauri gum in pure spirits of turpentine. 
 
 7. (a) A distillation flask, water-cooled condenser and a tared receiver 
 shall be arranged on a balance. Clear, bright, hard pieces of Kauri gum 
 broken to the size of a pea shall be placed in the flask to about one-third its 
 eapacity. The gum shall be carefully melted and distilled until 25 per cent 
 by weight is collected in the tared receiver. At the end of the distillation the 
 thermometer in the distillation flask with the bulb at the level of the dis- 
 
 a, aoe 
 
 wor ee te 
 
 we Teen 
 
 ve... 
 
Analysis of Varnish 457 
 
 charging end of the flask should register about 316° C. (600° F.). The residue 
 shall be poured into a clean pan and when cold it shall be broken into small 
 
 pieces. 
 
 (b) Standard Run Kauri Solution.—A quantity of the small broken pieces 
 of Run Kauri, together with twice its weight of freshly re-distilled spirits of 
 turpentine, using only that portion distilling between 153 and 170° CC. (308 
 and 338° F.), shall be placed in a carefully tared beaker and dissolved by 
 heating to a temperature of about 149° C. (300° F.). It shall then be brought 
 to correct weight when cooled by the adition of the amount of re-distilled 
 spirits of turpentine necessary to replace the loss by evaporation during the 
 dissolving of the gum. 
 
 8. (a) Having carefully determined the non-volatile content of the 
 varnish in accordance with Section 4, 100 parts of the varnish by weight shall 
 be taken and to it shall be added an amount of the standard Run Kauri 
 solution equivalent to 50 per cent by weight of the non-volatile matter in the 
 varnish and mixed thoroughly. 
 
 Note.—The 50-per-cent standard Run Kauri reduction is given to illustrate 
 the method. Any other percentage of standard Run Kauri reduction may be 
 used, depending on what is required of the particular sample being tested. 
 
 (vb) The varnish shall be flowed upon one of the tin panels described in 
 Section 1 (d) and the panel be permitted to stand in a nearly vertical position 
 at room temperature for nearly one hour. The panel shall then be placed 
 in a horizontal position in a properly ventilated oven and baked for five hours 
 at from 95 to 100° C. The panels shall then be removed from the oven and 
 permitted to cool at room temperature (preferably 24° C. (75° F.)) for 15 
 minutes. | 
 
 9. The panel shall be placed with the varnished side uppermost over a 
 3 mm. (1-in.) rod, held firmly by suitable supports, at a point equi-distant 
 from the top and bottom edges of the panel and bent double rapidly. The 
 varnish shall show no cracking whatsoever at the point of bending. For accu- 
 rate results the bending of the panel should always be done at 24° C. (75° F.) 
 for a lowering of the temperature will lower the percentage of reduction that 
 the varnish will withstand without cracking, while an increase in tempertaure 
 increases the percentage of reduction that the varnish will withstand. 
 
 10. Varnishes which do not show cracks under this test shall be reported 
 as passing a fifty-per-cent reduction while those that do crack shall be reported 
 as not passing a fifty-per-cent reduction. 
 
 The varnishes which have not cracked shall be tested again, changing the 
 amount of reduction to sixty per cent, and, if they pass this amount of reduc- 
 tion, they shall be reduced to seventy per cent. 
 
 In a similar manner, varnishes which have cracked at fifty per cent shall 
 be tested, using reductions of thirty and forty per cent. 
 
 In this way the limits shall be determined within ten per cent at which a 
 varnish passes one amount of reduction and does not pass the next. For 
 example, varnishes may be reported as passing forty per cent, and breaking 
 at fifty per cent. 
 
 NotE.—It is suggested that a 20-g sample of varnish shall be sufficient for 
 each reduction. If the non-volatile content of the varnish should be 48.6 per 
 cent, then 4.86 g. of standard Run Kauri solution should be added to the 20 g. 
 of varnish and a fifty-per-cent reduction will be obtained. 
 
458 Analysis of Varnish 
 
 eT 
 
 FLASH POINT 
 The flash point shall be determined in accordance with the Standard Method 
 of Test for Flash Point of Volatile Flammable Liquids (Serial Designation: 
 D 56) of the American Society for Testing Materials. 
 
 VISCOSITY 
 Viscosity shall be determined by comparison at 25° C. (77° F.) with 
 secondary standards whose viscosity expressed in poises has been accurately 
 determined at that temperature. 
 Notr.—Gardner-Holdt tubes may be used. See Circular No. 178, Scientific 
 Section, Paint Manufacturers’ Association of the U. S. 
 
 WATER TEST 
 The varnish shall be poured on one of the standard tin panels and allowed 
 to drain in a nearly vertical position and dry for 48 hours. The panel shall 
 be placed in a beaker containing about 7 cm. (2.5 in.) of distilled water at 
 room temperature (immersing the end of the panel which was uppermost 
 during the drying) and left in water for 18 hours. The panel shall then be 
 removed from the water, wiped carefully, and allowed to dry out at room 
 temperature. The time required for whitening, if any, to disappear, shall be 
 noted. The results of the water test shall be reported as follow: 
 (1) Not visibly affected. 
 (2) Whitening disappears within 20 minutes. 
 (3) Whitening does not disappear in 20 minutes, but does disappear 
 within 2 hours. 
 (4) Whitening does not disappear within 2 hours, but does disappear 
 within 24 hours. 
 (5) Whitening does not disappear within 24 hours. 
 Blooming, which sometimes occurs on immersion, is considered as a degree 
 of whitening, 
 
 A. 8S. T. M. TENTATIVE METHODS OF TESTING 
 INSULATING VARNISH 
 
 1. These tests are intended for varnishes which are applied by brushing, 
 dipping or spraying, and are primarily for the purpose of providing electrical 
 insulation. 
 
 I. SPECIFIC GRAVITY. 
 
 2. The specific gravity shall be measured with a pyknometer, Westphal 
 balance or with a hydrometer so graduated that the specific gravity can be 
 determined to 0.001. The temperature of the varnish shall be not less than 18° 
 C. (64.4° F) nor more than 22° C. (71.6° F.) and corrected to 20° C. (68° F.) 
 by applying a correction of 0.0007 per 1° C. (0.0004 per 1° F.). 
 
 II. VISCOSITY. 
 3. The viscosity shall be determined at 20° C. (68° F.) and the results 
 shall be stated in terms of absolute viscosity—poise* or centipoise (centi- 
 poise — 0.01 poise). 
 
 *The absolute viscosity of a material or its viscosity in absolute units 
 (c.g.s., poises) has been defined as the force in dynes required to move, at a 
 velocity of 1 cm. per second, one surface having an area of 1 sq. cm. past 
 another parallel like surface 1 cm. away, overcoming the resistance to shear 
 of the material filling the space between. 
 
Analysis of Varnish 459 
 
 Nore 1.—When measurements are made by an indirect method, the instru- 
 ment used must be standardized. Oils of standard viscosity for use in stand- 
 ardizing such instruments can be obtained from the U. S. Bureau of Standards. 
 
 Note 2.—A description of the MacMichael viscosimeter as remodeled and 
 improved for varnish testing may be obtained from the secretary of Committee 
 D-9 together with directions for its calibration in absolute units. 
 
 III. FLASH POINT. 
 4. The flash point shall be determined in accordance with the Standard 
 Method of Test for Flash Point of Volatile Flammable Liquids (Serial Desig- 
 nation: D 56) of the American Society-for Testing Materials.* 
 
 IV. TIME OF DRYING. 
 
 5. (a) Specimens for this test shall be pieces of thoroughly cleaned, smooth 
 sheet copper or brass about 3 cm. (1.18 in.) wide and 20 cm. (7.88 in.) long 
 and about 0.127 mm. (0.005 in.) thick. 
 
 (b) The specimen shall be dipped once in the varnish at a room tempera- 
 ture of approximately 20° C. (68° F.) and withdrawn slowly and uniformly 
 (about 38 em. (15 in.) per minute). The consistency of the varnish shall be 
 first so adjusted by trial that, when dry as determined in accordance with Sec- 
 tion 7, the thicknes of the film of varnish on each side of the metal shall be 
 between 0.022 mm. (0.0009 in.) and 0.026 mm. (0.001 in.). Care shall be taken 
 before dipping the specimens that the varnish has stood in the dipping tank 
 for a sufficient length of time to be free from air bubbles. 
 
 6. (a) Specimens of air-drying varnish shall be dried in dust-free air at 
 a room temperature of approximately 20° C. (68° F.). 
 
 (b) In the case of baking varnishes, six specimens shall be dipped and 
 allowed to drain at a room temperature of approximately 20° C. (68° F.) until 
 the varnish is set as indicated when the impression left on the surface by 
 pressing lightly thereon with a finger will not become obliterated by further 
 flow of the material. They are then to be dried in dust-free air in an oven 
 at 105 to 110° G. (221 to 230° F.). At the end of the first 30 minutes, and 
 again at the end of each 10-minute period thereafter, one specimen shall be 
 taken from the oven and examined. In the case of slow-drying varnishes, 
 this 10-minute period may be lengthened at the discretion of the operator. 
 
 7. The varnish shall be considered dry when a specimen will not stick to 
 itself when folded and pressed together between the thumb and finger at a 
 temperature of approximately 20° C. (68° F.). 
 
 V. DIELECTRIC STRENGTH TEST. 
 
 8. (a) Specimens for the dielectric strength test shall be prepared by 
 dipping pieces of kraft paper about 20 cm. (7.88 in.) square and about 0.076 
 mm. (0.003 in.) thick into the varnish which shall be at the consistency pre- 
 seribed in Section 5 (6). 
 
 Note.—The paper used shall be that which is commercially known as No. 1 
 Sulfate Kraft. The surface of the paper shall be smooth, free from pimples 
 or lumps and reasonably free from hairy fibers. The paper shall also be free 
 fishy conducting particles, slime spots, creases, cuts, specks or other “paper 
 
 efects.” 
 
 *1924 Book of A.S.T.M. Standards. 
 
460 Analysis of Varnish 
 
 (b) Hach specimen shall be dipped twice, as specified in Section 5 (5b), 
 once in each direction, in order to give a more uniform thickness of coating. 
 The specimen shall be dried after each dip in the same vertical position in 
 which it was dipped. 
 
 (c) Specimens of air-drying varnish shall be dried in dust-free air after 
 each dip at a room temperature of approximately 20° C. (68° F.) for a period 
 600 per cent longer than that determined in accordance with Section 7, pro- 
 vided such period does not exceed 24 hours. 
 
 (d) Specimens of baking varnish shall be drained and then baked in dust- 
 free air after each dip for a period 300 per cent greater than that determine: 
 in accordance with Section 7, provided such period does not exceed 24 hours. 
 
 (e) The final thickness of the specimen shall be 0.152 mm. (0.006 in.) to 
 within + 15 per cent. 
 
 9 (a) The dielectric strength of the specimen shall be determined by 
 applying alternating potential to two circular metal disks, 5.08 cm. (2.0 in.) 
 in diameter and with edges rounded to a radius of 0.64 em. (0.25 in.) which 
 are placed in contact with the two sides of the specimen directly opposite 
 
 each other and under a pressure of approximately 0.5 kg. (1.1 Ib.). Starting 
 
 at zero, the voltage shall be increased uniformly to breakdown at a rate of 0.5 
 kilovolt per second, except that if breakdown occurs at this rate in less than 
 40 seconds, the rate shall be decreased so that breakdown will occur in not 
 less than 40 seconds. If the material fails at less than 5 kilovolts, the mini- 
 mum time shall be reduced from 40 seconds to 20 seconds. Ten such punc- 
 tures are to be made at various points selected at random on each specimen. 
 In each test the thickness of the specimen is to be determined as close to the 
 point of puncture as practicable. 
 
 Normr.—When necessary, in order to get ten punctures, additional specimens 
 should be tested. 
 
 (b) The frequency of the test potential shall be not greater than 100 cycles 
 per second, and each part of the testing apparatus shall have a continuous 
 rating of not less than 2 kva. (preferably larger). The wave form shall be a 
 sine curve as defined, and the voltage shall be measured by methods approved 
 by the American Institute of Electrical Engineers.* 
 
 (c) The voltage may be controlled by any approved method which does 
 not distort the wave form beyond the limits prescribed above and which does 
 not subdivide the voltage in steps greater than 500 volts. The apparatus 
 shall comply with the Standards of the American Institute of Electrical 
 Engineers. 
 
 10. The volts at puncture, the thickness of the specimen and the volts per 
 mil of thickness shall be reported for each of the ten tests, together with the 
 average, maximum and minimum volts per mil. 
 
 Norr.—This test is relative only, but it gives more uniform results than » 
 
 those obtained with a copper base. See the Appendix for a procedure for 
 determining the dielectric strength on a copper base. 
 
 VI. WATER ABSORPTION TEST. 
 11. Specimens similar to those described in Section 8 shall be immersed 
 
 *Standards of the American Institute of Electrical Engineers. 
 
 ? 
 
 iz 
 + 
 # 
 ¢ 
 * 
 ‘a 
 o 
 
Analysis of Varnish 461 
 
 in water at a room temperature of approximately 20° C. (68° F.) for a period 
 of 24 hours. Upon removal from the water, the surface water shall be wiped 
 off and dielectfic strength tests made immediately as described in Section 9. 
 
 12. The volts at puncture, the thickness of the specimen and the volts per 
 mil of thickness shall be reported for each of the ten tests, together with the 
 average, Maximum and minimum volts per mil. 
 
 VII. HEATING ENDURANCE TESTS. 
 
 13. (@) For the heat endurance test, specimens shall be prepared by dip- 
 ping pieces of thoroughly cleaned, smooth sheet copper or brass about 20 em. 
 (7.88 in.) square and about 0.127 mm. (0.005 in) thick into the varnish which 
 shall be at the consistency prescribed in Section 5 (bd). 
 
 (b) The specimens shall be dipped twice as prescribed in Section 5 gee 
 
 (c) After removing not less than 1.27 cm. (0.5 in.) from one edge of the 
 specimens the number of strips required by Section 14 (a) shall be cut from 
 the same edge each 1.9 cm. (0.75 in.) in width. 
 
 14 (a) After setting as shown by the test indicated in Section 6 (b), the 
 strips referred to in Section 13 shall be placed in a uniformly heated oven in 
 which the temperature is maintained at 100° C. (212° F.) within + 5° ©. 
 (9° F.). A strip shall be removed at the end of 1, 2, 4, 8 and 24 hours respec- 
 tively and every 24 hours thereafter. These, together with the initial strip, 
 Shall be tested as follows at a room temperature of approximately 20° C. 
 (68°: F.). 
 
 (6) Each strip shall be bent through 180 deg. over a rod 0.32 cm. (% in.) 
 in diameter. The number of hours of baking at which first cracking in the 
 insulation occurs shall be noted and reported. 
 
 VIl. HEAT ENDURANCE TESTS. 
 
 15. The specimens to be used for the test for acid and alkali proofness 
 Shall be brass rods 1.5 cm. (0.59 in.) diameter, 15 cm. (5.90 in.) long and 
 carefully rounded at one end to a radius of 0.75 cm. (0.295 in.). These speci- 
 mens shall be dipped three times into the varnish, leaving exposed about 3 cm. 
 (1.18 in.) of the rod at the end opposite the rounded end. Each coat shall 
 be dried 25 per cent longer than the period determined in Section 7. These 
 specimens each shall be prepared for the acid and alkali solutions. 
 
 16. (a) The three specimens shall be suspended in the acid or alkali 
 whose effect it is desired to determine to within 3 cm. (1.18 in.) of the end of 
 the coated portion of the rod and suitable provision made for detecting the 
 change in the electrical resistance between the rod and the solution. (Note 1.) 
 
 Notre 1.—A simple method is to connect a voltmeter between each rod in turn 
 and one side of a 110 volt direct current circuit, the other side of the circuit 
 being connected to the solution through any piece of suitable metal suspended 
 in the solution. The resistance will be inversely proportional to the deflection 
 of the voltmeter pointer, that is, the smaller the deflection, the greater the 
 resistance. Failure of the material will, therefore, be indicated by a sudden 
 increase in the deflection of the voltmeter pointer. 
 
 (b) It is recommended that these tests be made in 10-per-cent solutions 
 as follows: 
 
 Sulfuric acid of sp. gr. 1.069 at 60° F. (15.5° CG.) or nitrie acid of sp. gr. 
 1.056 at 60° F. (15.5°) ©.) or hydrochloric acid of sp. gr. 1.050 at 60° F. 
 (15.5° C.) and sodium hydroxide of sp. gr. 1.115 at 60° F. (15.5° C.). 
 
462 Analysis of Varnish 
 
 (c) The temperature of the solution shall be kept at approximately 20° C, 
 (68° F.). 
 
 17. The resistance between each rod and the solution shall be measured 
 once per day and the number of days elapsing before breakdown occurs shall 
 be taken as the “proofness” of the varnish. 
 
 IX. OIL PROOF TEST. 
 18. (a) To test for the effect of oil, the specimens shall be prepared as 
 prescribed in Section 13:(@); 
 (b) The specimens shall be dipped and dried as prescribed in Sections 8 
 
 (b), (c) and (d). 
 
 (c) Test pieces shall be cut from the specimens as prescribed in Section 
 te (CC). 
 
 19. The effect of oil on the varnish shall be determined by immersing the 
 specimens in transformer oil at a temperature of 100° C. (212° F.) for 48 
 hours and noting the effect on the varnish as indicated, for example, by wiping 
 with a piece of dry white cloth. 
 
 Nore.—Incipient disintegration of the surface of the varnish may some- 
 times be detected by examining the oil for turbidity. ‘If a specimen of the oil 
 filtered through filter paper can be distinguished from an unfiltered sample 
 when the two samples are held in front of a strong light, the oil is turbid. 
 
 X. DRAINING TEST. 
 (ALso KNown AS ‘WORKING Viscosity” TEST) 
 
 20. A strip of bond paper 0.064 mm. (2.5 mils) in thickness, 10.2 cm. (4 in.) 
 in width and 50.8 cm. (20 in.) in length, shall be immersed in the varnish at 
 a room temperature of approximately 20° C. (68° F.) up to a line previously 
 drawn across the paper a few inches from the top. The paper shall be with- 
 drawn at a slow and uniform rate (about 38 cm. (15 in.) per minute), care 
 being taken that the varnish is free from air bubbles. The specimen shall be 
 permitted to drain thoroughly at room temperature while suspended in a 
 vertical position. It shall then be dried or baked (according to the type of the 
 varnish) until dry as determined in accordance with Section 7. 
 
 21. The thickness of the specimen in mils shall be measured at points 5.1 
 em. (2 in.), 17.8 cm. (7 in.) and 30.5 em. (12 in.), respectively, from the line 
 to which the specimen was immersed. 
 
 29 The thickness of each film in mils at the three points specified in Sec- 
 tion 21 shall be recorded. The difference between the thickness at the upper 
 point (5.1 em.) and that at the lower point (30.5 em.) shall be taken as a 
 measure of the variation in the film thickness caused by draining. 
 
 XI. EVAPORATION TEST. 
 
 22. One hundred cubie centimeters of the varnish shall be placed in a flat- 
 bottom erystallizing dish approximately 75 mm. (2.95 in.) in diameter and 45 
 mm. (1.77 in.) in height. It shall be heated to a temperature Of 1007 ke 
 (37.8° C.) + 2° F. (1.1° C.) for a period of 7 hours, the sample being exposed 
 to still air in the open room. 
 
 24. The decrease in volume of the sample shall be taken as the evapora- 
 tion, this decrease being determined by noting the amount of water or kerosene 
 that must be added to fill the dish to the original level. . 
 
 ee ee ee a eee 
 
Analysis of Varnish - 463 
 
 Nore.—This test is relative only. That is, it is only suitable for comparing 
 one varnish with another when the tests are made simultaneously under 
 exactly the same conditions. 
 
 XII. TEST FOR NON-VOLATILE MATTER. 
 
 25. A portion of the sample shall be placed in a stoppered bottle or weigh- 
 ing pipette and weighed. About 1.5 g. of the sample shall be transferred to a 
 weighed flat-bottom metal dish about 8 cm. (3.15 in.) in diameter, such as the 
 cover of a friction-top tin can. The container shall again be weighed and the 
 exact weight of the portion of the sample transferred to the weighed dish 
 calculated by difference. The dish with its contents shall be heated for three 
 hours in an oven maintained at 105 to 110° C. It shall then be weighed after 
 cooling. ( 
 
 26. The ratio of the weight of the residue to that of the original sample 
 expressed as a percentage shall be taken as the percentage of non-volatile 
 matter in the varnish. 
 
 APPENDIX. 
 
 y 
 
 Where it is desired to make dielectric strength tests of solid films of varnish 
 (as distinguished from the specimens prescribed in the methods, which are a 
 combination of varnish and paper fibers), it is recommended that copper be 
 used as the base as formerly required in the methods. The following are the 
 directions for preparing and testing such specimens: 
 
 1. (@) Specimens are prepared by dipping pieces of thoroughly cleaned, 
 smooth sheet copper or brass about 20 cm. (7.88 in.) square and about 0.127 
 mm. (0.005 in.) thick into the varnish which is at the consistency prescribed 
 in Section 5 (b) of the methods. 
 
 (b) Hach specimen is dipped twice, once in each direction, in order to give 
 a more uniform thickness of coating. The specimen is dried after each dip in 
 the same vertical position in which it was dipped. 
 
 (c) Specimens of air-drying varnish are dried in free air after each dip 
 at a room temperature of approximately 20° C. (68° F.) for a period 600 per 
 cent longer than that determined in accordance with Section 7 of the methods 
 provided such period does not exceed 24 hours. 
 
 (d) Specimens of baking varnish are drained and then baked after each 
 dip for a period 300 per cent greater than that determined in accordance with 
 Section 7 provided such period does not exceed 24 hours. 
 
 (e) The final thickness of the film of varnish on each side of the specimen 
 is between 0.044 mm. (0.0018 in.) and 0.052 mm. (0.002 in.). 
 
 2. (a) The dielectric strength of the two films of varnish is determined by 
 applying alternating potential to two circular metal disks, 5.08 em. (2.0 in.) in 
 diameter and with edges rounded to a radius of 0.64 em. (0.25 in.) which are 
 placed in contact with the two sides of the specimen directly opposite each 
 other and under a pressure of approximately 05 kg. (1.1 1b.). Starting at zero, 
 the voltage is increased uniformly to breakdown at a rate of 0.5 kv. per 
 second, except that if breakdown occurs at this rate in less than 40 seconds, the 
 rate shall be decreased so that breakdown will not occur in less than 40 
 seconds. Ten such punctures are to be made at various points selected at 
 random on each specimen, In each test the thickness of the films of varnish 
 is to be determined as close to the point of puncture as practicable. : 
 
 Nore.—When necessary, in order to get ten punctures, additional Specimens 
 ‘should be tested. 
 
 (b) The frequency of the test potential shall be not greater than 100 cycles 
 per second, and each part of the testing apparatus shall have a éontinuous 
 rating of not less than 2 kva. (preferably larger). The wave form shall be a 
 
464 Analysis of Varnish 
 
 sine curve as defined, and the voltage shall be measured by methods approved 
 by the American Institute of Electrical Engineers. ; 
 
 (c) The voltage may be controlled by any approved method which does 
 not distort the wave form beyond the limits prescribed above and which does 
 not subdivide the voltage in steps greater than 500 volts. The apparatus shall 
 comply with the Standards of the American Institute of Electrical Engineers. 
 
 8 The volts at puncture, the net thickness of insulation and the volts per 
 mil of net thickness shall be reported for each of the ten tests together with 
 the average maximum and minimum volts per mil. 
 
 ee 
 
CHAPTER XXV 
 
 MISCELLANEOUS TESTS ON VARNISHES 
 
 There is given below a series of miscellaneous tests which 
 may be of general interest to the varnish chemist. 
 
 Testing the Acid Value of Varnishes.—In a study of various 
 methods to determine the acid value of varnish products, a sub- 
 committee of the Committee on Varnish of the American 
 Society for Testing Materials sent out samples of several var- 
 nishes made by varying processes and containing different 
 gums and oils. Five different methods for determining the 
 acidity were included. Of these methods, Nos. 3 and 4 were 
 found to give the most closely checking results. Method 5 was 
 also found desirable on account of good end points obtained, 
 and since that method can be used for dark colored varnishes, 
 it should be of general interest. These three methods are 
 presented below. 
 
 Method III (suggested by EK. A. Stoppel).—Materials.— 
 Weight of sample taken, 10 g. Volume of ether, U. S. P., 100 
 ec. Alcoholic KOH or NaOH 0.5 N. Indicator 1 per cent alco- 
 hohe phenolphthalein. : 
 
 No heating is required for solution, although 2 to 5 minutes 
 with shaking is usually allowed for complete solution. Titra- 
 tion with shaking is continued until a pink color is reached. 
 If the acid number of the varnish is very high, 0.2 N alkali is 
 recommended. The method, of course, is applicable to oils 
 and resins as well as varnish. 
 
 Method IV (suggested by M. Neidle).—Applicable to ma- 
 terials whose color will not mask the phenolphthalein end 
 point. 
 
 To a suitable weight of sample in a 300 to 500-cc. Erlen- 
 meyer flask add 50 ec. of benzol or xylol. Mix until uniform, 
 heating if necessary. 
 
 Add 50 ce. neutralized denatured alcohol, and titrate with 
 approximately 0.5 N aqueous NaOH, using phenolphthalein as 
 indicator. If more than 25 cc. of NaOH has been used, add 
 00 ee. more of neutralized denatured alcohol and continue the 
 titration until, after shaking, the color persists for at least 
 two minutes. Vigorous shaking during titration is essential 
 for the proper distribution of the acid. | 
 
 When the final end point is taken, the volume of alcohol 
 should be twice that of the water in the mixture. 
 
466 Miscellaneous Tests on Varnishes 
 
 Method V.—Applicable to materials whose color would or- 
 dinarily mask the phenolphthalein end point, for example, as- 
 phaltum varnishes, cotton pitches, very dark gum goods; also 
 useful where metallic soaps are precipitated when alcohol is 
 added. 
 
 To a suitable weight of material, add 50 ec. of benzol or 
 xylol. Mix until uniform, heating if necessary. Then add 
 50 ec. of carbon tetrachloride, a mixture of 50 ce. of neutral- 
 ized denatured alcohol and 10 ce. of water, 14 teaspoonful of 
 sodium chloride and a little phenolphthalein indicator. After 
 mixing well, a clear layer should quickly separate on top. 
 
 Now, titrate with 0.5 N aqueous NaOH, with vigorous shak- 
 ing until, on standing, the top layer is pink and remains so for 
 at least two minutes. 
 
 If more than 15 ec. of NaOH has been used, add 50 ce. more 
 of neutralized denatured alcohol, shake, and continue the 
 titration if the color has been discharged. When the final end 
 point is taken, the total volume of alcohol should be at least 
 twice that of the water in the mixture. 
 
 A first determination may be over-stepped and brought back 
 with 0.5N H.SO,. The second determination should then give 
 a sharp end point within one or two drops of the alkali. 
 
 Note.—The purpose of the carbon tetrachloride is to obtain 
 a solvent layer of high specific gravity. Water is added to the 
 aleohol to destroy the miscibility of the latter with the ether 
 solvents present. The sodium chloride reduces the tendency 
 towards emulsification. 
 
 Testing Gas Resistance.—The gas test referred to in Bureau 
 of Standards Cireular No. 117, while having proved generally 
 satisfactory, is according to one observer, not as satisfactory 
 as one in which fresh flowouts of the varnishes are placed in a 
 small cabinet two feet square, in which two Bunsen burners 
 with luminous flames are just burning. Comparisons can be 
 made as soon as the tack-free period of drying is passed. This 
 method of test is practical and severe, and has been used with 
 satisfactory results. | 
 
 A more elaborate and decisive method of testing a varnish 
 for resistance to gasses has been devised by W. W. Bauer.” 
 It consists of passing nitric oxide through a bell jar in which 
 are placed the panels to be tested. 
 
 Testing the Livering Properties of Varnishes.—In deter- 
 mining whether a varnish will be suitable as a mixing liquid 
 
 * Ind. and Eng. Chem., 18, 1249 (1926). 
 
467 
 
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 Miscellaneous Tests on Varnishes 
 
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468 Miscellaneous Tests on Varnishes 
 
 in an enamel, the writer has generally used for this purpose 
 a paste made of 80 parts by weight of zine oxide and 20 parts 
 by weight of refined linseed oil. To 40 parts of this paste, 60 
 parts by weight of varnish is added, and the mixture thor- 
 oughly stirred. It is allowed to stand in a small, partially 
 open evaporating dish for a period of six weeks. The charac- 
 ter of skin formed upon the surface should be noted. If var- 
 nishes contain a very large amount of drier, the skin formed 
 will probably be very brittle and comparatively thin. Var- 
 nishes which contain a small amount of drier generally pro- 
 duce skins which are tougher and thicker. The use of var- 
 nishes containing an excess of manganese very often gives a 
 pink tint to the enamel mixture. If livering occurs, it may 
 be detected by roughly gauging the consistency of the paste 
 with a spatula. If sufficient of the enamel has been made up, 
 its increase in body may be watched by running mobilometer 
 tests every week. There is given below a chart showing the 
 results of tests of the above character, which were conducted 
 upon a number of varnishes. 
 
 Alkali Increase Test for Tung Oil Varnishes.— When a solu- 
 tion of sodium or potassium hydroxide is added to certain 
 tung oil varnishes, the resulting mixture becomes extremely 
 viscous. Other tung oil varnishes, differently processed, show 
 a much smaller increase in viscosity after the addition of an 
 equivalent amount of alkali. Two batches made on approxi- 
 mately the same formula may have the same acid value and 
 initial viscosity, yet through differences in manipulation or 
 cooking, may differ greatly in viscosity after the addition of 
 alkali. When linseed oil varnishes are alkali treated, the 
 viscosity increase is in general much smaller than in the case 
 of tung oil varnishes. 
 
 The writer has recently applied a so-called ‘‘ Alkali Increase 
 Test’’ to a number of commercial varnishes. Hxperiments 
 were also made on a tung oil varnish of fixed composition. 
 The results are given in the pages which follow. ‘This test, 
 which has previously been used in research work, presumably 
 yields a measure of the extent to which the oil has been poly- 
 merized during cooking. It may also indicate roughly the 
 collodial condition. The test is made in the following man- 
 ner. The viscosity of the varnish is first measured by one 
 of the usual methods. To a fresh portion of the sample, a 
 
Miscellaneous Tests on Varnishes 469 
 
 fixed quantity of definite strength alkali solution is added and 
 the viscosity of the mixture determined at the same tempera- 
 ture as used for the untreated sample. 
 It is necessary that standard conditions be observed in mak- 
 ing the test. The results obtained with a given varnish are 
 Note.—The original method of alkali increase was developed by one of the 
 
 writer’s former associates, R. E. Coleman, working with Messrs. Seaton, 
 Sawyer and Probeck. Acknowledgment for this early work is herewith made. 
 
 greatly affected by temperature, concentration of the alkah, 
 time elapsing between alkali addition and viscosity reading, 
 ete. In the experiments herein described a Doolittle visco- 
 meter was used, readings being taken with a one-inch spindle 
 in all cases. The thermometer employed was graduated in 
 tenths of a degree Centigrade; the temperature being main- 
 tained as nearly as possible at 25° C. during determinations. 
 A 10% solution (2.5 N) of sodium hydroxide was used. 
 
 Method Used for Taking Alkali Increase.—Measure out 
 exactly 10 cc. of 10% (2.5 N) aqueous NaOH solution in a 
 small graduate. Measure 200 ec. of the varnish in a 200 ce. 
 graduate. Pour the varnish into a 300 ee. beaker and allow 
 the cylinder to drain for exactly one minute. Add the meas- 
 ured quantity of NaOH solution to the varnish quickly, at the 
 same time stirring vigorously. Continue the stirring for ex- 
 actly two minutes, then transfer the mixture to the viscometer 
 cup. Allow to stand in the viscometer bath for thirty minutes 
 after stirring the varnish has ceased. (Bath should previously 
 have been brought to desired temperature, 25° C.)- Main- 
 tain bath as nearly as possible at 25° C. for the required thirty 
 minutes, taking a temperature reading a few minutes before 
 the viscosity reading. Read the viscosity exactly thirty min- 
 utes after completing the stirring. 
 
 Several viscosity and alkali increase readings should be 
 taken. In the writers’ experiments, the second alkali increase 
 reading appeared to be the most accurate and most readily 
 reproducible, hence was taken as the correct value. 
 
 Lest on Commercial Varnishes——Table 59 gives the results 
 of tests on commercial lots of well known brands of varnishes. 
 Table 59 indicates that there may be no relation between acid 
 value and the increase in viscosity after the addition of alkali. 
 For instance, Sample No. 3, which had the highest acid value 
 of the samples examined, had an alkali increase viscosity 
 
470 Miscellaneous Tests on Varnishes 
 
 which was easily measureable. Sample No. 6, on the other 
 hand, had the lowest acid value but showed a much greater 
 increase in viscosity with alkali addition than did No. 3. 
 
 Of the eleven samples examined, the alkali increased viscos- 
 ity was so great as to be measurable in only four cases. It is 
 probable that readings could have been made on these var- 
 nishes if they had first been thinned to a greater extent with 
 turpentine. This procedure is suggested to those wishing to 
 
 TABLE 59 
 en Nn nares eee 
 
 Viscosity Alkali Increase Acid Oil Used in 
 
 Varnish at 25° C. Viscosity at 25" 43 ape Varnish 
 a 
 4S Miia eee 25.0 42.0 7.5 Linseed 
 9 Boot. Tope 45.0 Too great to measure 11.4 Tung 
 3 ht eIOt ees 15.0 107.0 22.0 Linseed 
 4... Agricultural... 45.0 Too great to measure 14.0 Mostly tung 
 5 o> Mnterior aware 28.5 137.0 20.7.» Lanseed 
 6) Spare ncc ae 28.5 Too great to measure 4.1 15 tung to 1% lin- 
 seed 
 To Motor Caria. dia 39.0 Too great to measure 9.3 20 tung to 30 lin- 
 seed 
 8...c Floor Gaes re ee 32.0 127.0 12.9 % tung to 14 lin- 
 seed 
 0. > Motor Car ses 28.0 Too great to measure 6.8 Mostly tung 
 10. Rubbing Swe: 98.5 Too great to measure 21.9 Tung 
 11° Bootibonicrsee 44.0 Becomes solid 7.3. Lang 
 
 a 
 
 do further work on the method. Viscosity reading might also 
 be obtained after two minutes rather than thirty minutes, on 
 such products as are very high in viscosity after alkali addi- 
 tion. 
 
 Three of the four varnishes listed above contained linseed 
 oil only. The others consisted of linseed oil and tung oil. ‘The 
 resin content, which was unknown to the writers, undoubtedly 
 had a considerable effect on the reading. 
 
 Possible Application of the Test—While the test might 
 find application as a control test in processing tung oil var- 
 
Miscellaneous Tests on Varnishes 471. 
 
 nishes, it would probably prove most useful in research work. 
 For instance, it has been found that an oil or varnish which 
 shows a high increase in viscosity with alkali addition fre- 
 quently livers or thickens up with active pigments even though 
 it may be practically neutral. 
 
 When considered in connection with viscosity the test will 
 also indicate variations in processing. Two batches of a 
 treated oil or varnish made on the same formula may show 
 identical viscosities, yet through variations in the cooking or 
 in the bodying of the materials in the formula, may show en- 
 tirely different alkali increase factors and behave differently 
 when mixed with pigments. 
 
 Preliminary tests have also shown that drying characteris- 
 ties may vary with changes in the alkali increase. 
 
 In routine work the test might be used to determine whether 
 different batches of the same varnish were coming through 
 the same. Each varnish so processed as to have certain defi- 
 nite characteristics would show an alkali increase which might 
 vary between fairly narrow limits without materially affect- 
 ing those characteristics. These limits, if once determined 
 and thereafter adhered to, should assist materially in insuring 
 uniformity. Instead of testing each individual batch, a tank 
 might be tested after having stood a specified length of time 
 and before being canned. 
 
 Testing the Speed of Evaporation of Varnish Thinners.— 
 Oleo-resinous varnishes usually contain from 40 to 60% of 
 ‘‘thinners’’ such as turpentine, mineral spirits or similar or- 
 ganic volatile liquids having quite wide variations in boiling 
 points. The rate of drying of such varnishes has been con- 
 sidered as dependent to some extent upon the character and 
 amount of thinners present. 
 
 That mineral spirits will evaporate more slowly than tur- 
 pentine from a varnish film is well known. ‘The effect of the 
 type of hydrocarbon upon the rate of evaporation has hereto- 
 fore apparently lacked investigation. The proportion of the 
 various fractions of widely different boiling points which 
 make up the hydrocarbon thinning liquids is also a matter 
 of considerable importance. In addition to the influence of 
 the above factors upon the drying of a varnish may be men- 
 tioned the effect of the thinner upon the viscosity of the thin- 
 ned varnish. The experiments described herein were con- 
 
472 Miscellaneous Tests on Varnishes 
 
 ducted for the purpose of securing information along the 
 above lines. 
 
 In order to secure exact data on the subject a series of 
 thinners of widely varying boiling points—namely, turpen- 
 tine, mineral spirits, solvent naphtha, benzine and benzol— 
 were experimented with. The varnish bases were prepared 
 in a varnish plant in 100-gallon kettles. One was a short oil 
 interior rubbing varnish containing about 7 gallons of varnish 
 makers’ linseed oil to 100 pounds Kauri gum; the other a long 
 
 Ficure 181 
 
 Weighing Bottle Used in 
 Tests 
 
 oil spar varnish containing about 24 gallons of Tung oil and 12 
 gallons of alkal-refined linseed oil to 100 pounds of combined 
 varnish resins. These varnish bases were sent to the labora- 
 tory without added thinner. 
 
 The varnish solutions were prepared by warming the base 
 until it became liquid enough to incorporate the thinner, care 
 being taken to avoid excessive heating. Both base and thin- 
 
473 
 
 Miscellaneous Tests on Varnishes 
 
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Miscellaneous Tests on Varnishes 
 
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476 Miscellaneous Tests on Varnishes 
 
 ner were very carefully weighed* before mixing. All samples 
 were reweighed after mixing to insure that there had been no 
 appreciable loss of volatile during the mixing. In no case, 
 except with certain of the lower individual fractions, was the 
 loss sufficient to require further addition of thinner to secure 
 the desired percentage of ingredients. The amount of thinner 
 did not vary in any case by more than a fraction of 1% from 
 that shown in the tables. 3 
 
 In Table 60 is presented a distillation chart of the various 
 thinners used. The mineral spirits were of a high grade com- 
 mercial type meeting the specifications of the Federal Specifi- 
 cations Board. Benzine, benzol, and solvent naphtha were 
 average commercial samples of good quality. The turpentine 
 was a few months old and left a rather high viscous residue, 
 but was satisfactory otherwise. 
 
 Small bottles were tightly fitted with corks into which were 
 fastened small brushes. (See Fig. 181.) A few grams of var- 
 nish were poured into one of the bottles, and the cork set 
 tightly in place so as to prevent evaporation. The bottle, with 
 its brush and contents, was then weighed. The cork was then 
 removed with its contained brush and the varnish thereon 
 quickly applied to a weighed glass plate. The bottle was 1m- 
 mediately corked and reweighed. The difference in the weight 
 of bottle and contents before and after applying the film gave 
 the weight of the film. 
 
 Similar work has just been conducted by the writer on vola- 
 tile solvents used in making Pyroxylin Lacquer Coatings (see 
 page 637). 
 
 * Results throughout are based on percentage of volatile by weight. 
 
 ee ee ee ne me ge ee ee 
 
 ee ee es Neg Ee 
 
 a ee oe 
 
Miscellaneous Tests on Varnishes 477 
 
 Testing The Influence of Thinners.—There is given below 
 the approximate viscosity of varnish thinned with various 
 thinners in the proportion of 50 parts by weight of the same 
 varnish base and 50 parts by weight of thinner. These tests 
 were made with the Gardner-Holdt Viscometer tubes: 
 
 Paraffin Petroleum Thinners 
 
 Poises 
 I ye sg. is vice bs cyaiwid oe sins sicie eu sestedtelmesaes 1.65 
 CREE ET CGLOI ees dacs vcs oie cw p-aidc Gav ese rence ca vens 2.00 
 Meremierntcarmiineral Spirits “A”... oi. ce cece pews scacuscevus 2.00 
 LASSER US 055 Sa iu a a a 3.20 
 OE EA CEROIUY cre ovine y's eh cislc'e fcc des Sick Bele edwied cuales bees 3.20 
 Sua EE CLOT peice. Aon sec bob ccksd bgicelelece’s'va,c'e snes acuesdae 4.00 
 Equal Mixture of Fractions (175-181° C. and 225-235° ©.)...2.. 6.00 
 CECA oe. be. sis chs ns vc cv ci vyy eos coe no suites on acee 7.00 
 ee er CULT ie on vets s vic wp c'bib es o'd'saice ges ebveeeesaee 9.00 
 
 Cyclic Hydrocarbon Thinners 
 
 RUIN MEER ect oo Ox ba cic aslo dete chic soaaceadesvacdees 4.00 
 TPR TINENEA ee RS, cit, wince Gin aodweceebeecsaces 8.00 
 SMM MMM Mec eh oo i saw eagle ois. eae s Ace's Gc eens cease 10.00 
 
 Relation Between Kauri Reduction and Exposure Tests.— 
 There seems to be some relation between the results obtained 
 with the kauri gum reduction test for elasticity of varnishes, 
 and results obtained by actual exposures of such varnishes. 
 The writer recently exposed 26 varnishes which had previously 
 been tested for elasticity. The results of the exposure tests 
 divided the varnishes into two groups, namely, poor and good. 
 Ten of the varnishes had failed in the kauri gum reduction 
 test, and eight of these appeared in the poor group on expo- 
 sure. While these tests were not extensive and insufficient 
 information is available to make a broad statement on the sub- 
 ject, they would suggest that a relation seems to exist with 
 certain classes of varnishes. 
 
 A. S. T. M. TENTATIVE METHOD OF TEST FOR 
 ELASTICITY OR TOUGHNESS OF VARNISHES BY 
 ADDITION OF LINSEED OIL 
 
 1. This method applies to varnishes which are less elastic or tough than 
 zero Kauri reduction in the present Standard Methods of Testing Oleo-Resin- 
 ous Varnishes (Serial Designation: D 154) of the American Society for 
 Testing Materials. The method of test is identical with the present test 
 except that the 33%-per-cent solution of Run Kauri in turpentine is replaced 
 by a 66%4-per-cent solution of heat-bodied linseed oil for proportionately in- 
 creasing the elasticity of the varnish under test. 
 
478 Miscellaneous Tests on Varnishes 
 
 LS 
 
 PREPARATION OF STANDARD HEAT-BODIED LINSEED OIL 
 2. A high grade of alkali-refined linseed oil of an acid number of less than 
 1.0 shall be heated in an open kettle at a temperature of 300° C.+ 5° C. (572° 
 F.+9° F.) until the viscosity of the oil after cooling shall be between 6 and 
 10 poises at 25° C. 
 
 STANDARD BODIED-OIL SOLUTION 
 3. A quantity of the bodied oil shall be reduced with one-half its weight 
 of pure redistilled turpentine, using only that portion of turpentine distilling 
 between 158 and 170° C. (308 to-338° F.) 
 
 PROCEDURE 
 
 4. The addition of the standard bodied-oil solution to the varnish, the 
 flowing on panels, baking and bending shall be conducted exactly .as in the 
 Kauri reduction test described in the present Standard Methods D 154. In 
 reporting results, the minimum percentage of the oil solution that must be 
 added to the varnish, based on its non-volatile content, so the final mixture 
 when flowed on tin and baked does not crack on the subsequent bending over 
 a 3 mm. rod shall be reported. 
 
CHAPTER XXVI 
 
 COLOR STANDARDS FOR VARNISHES 
 
 Some plant managers consider it of importance to gauge the 
 color of certain varnishes so that batches made up will closely 
 approximate those produced at previous periods. The usual 
 means of accomplishing this is to keep samples for compari- 
 son. It has been found, however, that varnish samples kept 
 in glass and exposed to hight may show a substantial change 
 in color. Another method that has been used to sofne extent 
 is to make up a solution of 3 grams of potassium bichromate 
 in 100 ee. of pure sulfuric acid, limiting the darkness of var- 
 nishes to the depth of color shown by such a solution. This 
 solution, however, has the disadvantage of being quickly re- 
 duced, the yellow soon being replaced by a green tint. This 
 change is sometimes noticeable on a few hours’ standing. The 
 use of such a standard would, therefore, require the making 
 up of fresh solutions from day to day. A suggestion has been 
 made that a varnish slightly lighter in color than the standard 
 solution of bichromate referred to above be prepared and pre- 
 served as the standard for comparison. This, however, is not 
 always satisfactory, owing to the actual color changes which 
 take place even in varnish and to the limitation of having only 
 one standard rather than a number of graded colors. 
 
 The writer and P. C. Holdt have found a number of other 
 substances that fairly match varnishes in color but which un- 
 fortunately are not permanent. For instance, iodine solutions 
 fade in the light, metallic salt solutions such as ferric chloride 
 are affected by the alkalinity of glass containers, ultimately 
 throwing down precipitates and becoming lighter in color. 
 Organic dyestuffs experimented with have proved either de- 
 ficient in red or yellow, or subject to rather rapid loss of color 
 upon standing in the light. | 
 
 In the experimental work that has been conducted an at- 
 tempt was made to use a set of cube rosin standards ranging 
 from Gto WW. These were first melted and poured into per- 
 fectly dry, clear glass tubes such as are used for making bub- 
 ble viscosity test on varnishes. It was found, however, that 
 upon cooling the rosin would crystallize in the tubes, some- 
 times depositing long crystalline needles against the glass, 
 
480 Color Standards for Varnishes 
 
 causing an opacity which would obscure the color. Moreover 
 the gradations of color shown by the rosin standards were en- | 
 tirely unsatisfactory. 
 
 Asa result of a series of extended experiments, it was found 
 that the substance known as caramel (burnt sugar), when 
 diluted with water, produced clear solutions which exactly 
 match the yellow amber and red ruby colors produced by 
 various types of varnishes. In fact, the color effects produced 
 by different strengths of aqueous solutions of caramel more 
 closely approximate the colors of varnishes than any other 
 substance experimented with. After considerable prelimi- 
 nary work, a series of 12 caramel solutions varying in color 
 from almost water white to that of the darkest varnish, was 
 
 TABLE 61 
 ce. of caramel 
 
 Solution No. | ce. of water. solution. 
 
 14.5, Cee 99.8 0.2 
 
 De te ee ptiee aes 99.6 0.4 
 
 ps SA eis ei 98.9 Le 
 
 Ao ee Pee ' 97.6 2.4 
 
 SWeterar ce ea 96.3 Bet 
 
 6, vcusennae 92.6 7.4 
 
 Tn eee 88.9 Fisk 
 
 Rak Ree Si 18.5 
 
 Mae rite graces i "22 27.8 
 10 6.5 ee See 55.6 44.4 
 1d. ee eee 40.8 59.2 
 12 05 se eee tony 4 T7.8 
 
 prepared from a strong solution made by dissolving 165 grams 
 of liquid caramel syrup in 450 ce. of water.* This concentrated 
 solution was diluted with various proportions of water to 
 secure the desired range of colors met with, and ranging from 
 standard turpentine to the darkest grades of oleo-resinous 
 varnish. The concentration of each solution is given in Table 
 61. In making the dilutions, both water and caramel solu- 
 tions were accurately measured from a burette. 
 
 The solutions prepared as above were sterilized to prevent 
 fermentation and consequent change in color. In determining 
 the best method of sterilization, one set of samples was steril- 
 ized by heating a weighed amount of solution to boiling for a 
 few minutes in an Erlenmeyer flask fitted with an air con- 
 denser. After boiling, the flask was again weighed and a 
 
 * Commercial caramel varies greatly in concentration. Several samples 
 were purchased by the writer from various drug stores. The strength, however, 
 may easily be adjusted, using as a standard for one sample 3 grams of potas- 
 sium bichromate dissolved in 100 cc. pure sulfurie acid (spec. grav. 1.84). 
 
Color Standards for Varnishes 481 
 
 small amount of sterile water added to replace that driven off 
 by the heat. In making up another set of samples, one-half 
 of one per cent of sodium benzoate was added to each solution. 
 This sample was not boiled. A third set of solutions was 
 made up but was not sterilized. These three sets of samples 
 were examined at the end of three months. In the set that had 
 not been sterilized, there were large masses of fuzzy agglomer- 
 ates, indicating that considerable fermentation had taken place. 
 In the set sterilized by heat, there were small amounts of 
 fuzzy masses (possibly caused by some contamination in trans- 
 _ ferring the solutions to the sterilized tubes). The set of sam- 
 ples which had been sterilized with sodium benzoate showed 
 absolutely no evidence of fermentation. It was decided, there- 
 fore, that this method of sterilization is the best. Tater it 
 was found advisable to use 25 per cent of alcohol in the solu- 
 tions. 
 
 To test the permanency of the suggested color standards, 
 the color strength of each solution was determined by means 
 of the Lovibond tintometer in terms of both red and yellow. 
 These readings were then repeated at intervals of from two to 
 three weeks to determine whether any change was taking 
 place. The same set of tubes was used throughout, being 
 tightly corked after each reading. They were kept in the 
 laboratory upon a table in the light so as to afford every op- 
 portunity for color changes. The results on a series of four 
 readings are given in Table 62. It will be noted that there 
 was practically no change in the color of these standards be- 
 tween the first and the final readings. Any minor changes in- 
 dicated were so slight as to be attributable to experimental 
 error in observation rather than to change in the color of the 
 solution. As a check on the results, there was made up 
 on Oct. 12th another set of the standard solutions, by using 
 the same lot of caramel diluted to the same concentration and 
 sterilized by the same process. When these solutions were 
 compared with those made up three months before, upon 
 which the readings had been made, no change was shown. 
 
 From a strictly scientific point of view, it would be more 
 accurate to measure color strength of varnishes in terms of 
 wave length and to look for color changes with the aid of a 
 colorimeter. However, a variation in color that cannot be de- 
 termined by the unaided eye is of no importance in the pres- 
 ent connection, aS approximations only are desired. More- 
 
482 Color Standards for Varnishes 
 
 over, because of the high cost of accurately standardized col- 
 orimeters, such apparatus would not be available in most var- 
 nish factories. It is the writer’s belief, however, that a sim- 
 ple form of apparatus, such as is suggested in this chapter, 
 might be produced by anyone interested and quite satisfac- 
 torily serve the purpose for commercial work. 
 
 TARLE 62.—Color Strength of Caramel Solutions (Lovibond Tintometer ) 
 
 Ist Reading 2nd Reading 3rd Reading 4th Reading 
 
 Sam- | Size July 7th. July 15th. July 28th. Aug. 22nd. 
 
 ple (ell: fe eee eases Sete 
 
 No. i F 
 
 Yellow. | Red. | Yellow. | Red. | Yellow. | Red. | Yellow. | Red. 
 
 oe eee 1" 2.0 0 2.0 0 2.0 0 2.0 a 
 CUR aS 4" 3.0 2 3.0 a 3:0 2 3.0 7 
 ys or ae 1” 5.0 we 5.0 4°3 5.0 io 5.0 iy 
 aes ai 1” $6 we) 8.5 3 8.5 oO 8.5 2 
 ee, 14” 16.0 ioe aka TAVIS 7 nee i: ae 
 fea: 16” | 26.0 O44 26.0 Lesa 1. 35) 2540 1.35 
 ik: some 16” | 36.0 2:35 5070 2.6 | 36.0 3. OF 36.0 3.0 
 ieee & yy" | 30.0 1/75) 208 1.75) 30.0 2.04. 30-0 lea 
 LG ae Wy" | 42.0 4.0 | 42.0 4.5 | 42.0 4.7} 42.0 4.5 
 AA See iy") 51.0 bi Ole 8.0} 51.0 roe Oe eras 3 Be 7.5 
 12 Ase 1%” | 61.0. | 12.5 | 61.0 | 12.5) GIO) a ee 
 
 Nore: Because of the very light color (match for turpentine) of Sample No. 1 
 this was not included in the readings. 
 
 In order to test the permanency of the color of varnishes, 
 samples of exterior varnish, floor varnish, and rubbing var- 
 nish of well known commercial brands were selected. These 
 were placed in tubes in the original undiluted condition, and 
 also diluted with 25 per cent and with 50 per cent of pure 
 spirits of turpentine. Five sets of tubes thus prepared were 
 sealed airtight in viscosity bubble varnish tubes. ‘Two sets 
 of these sealed samples were wrapped separately in heavy 
 paper, placed in a box so as to completely exclude all light, 
 and so protected until the time of making a reading for color 
 value. Two other sets were exposed to ordinary daylight in 
 the laboratory but not to the direct rays of the sun. Read- 
 ings were taken on one set of the sealed tubes kept in the dark 
 and one set in the light, at the end of periods of one month. 
 On the sets kept in the dark, no appreciable change was ob- 
 served at the second reading. The sets kept in the light, how- 
 ever, showed considerable change. Readings on the latter are 
 given in Table 63. The change in some of these was suffi- 
 
Color Standards for Varnishes 483 
 — eee SSS 
 ciently great to be easily detected by the eye without the use 
 of an instrument. It is very interesting, however, to note that 
 the change is not always a lightening of color. For instance, 
 some samples had become very much darker in color. 
 
 TABLE 63.—Readings on Varnishes Haposed to Light, Showing Changes in 
 Color Values 
 
 Ist Reading 2nd Reading ord Reading 
 Aug. 22, 1921.| Sept. 13, 1921.) Oct. 11, 1921. 
 
 Sample. — BRE ey ee a Fe Eas, eee ees) te” ead ba ae acae 
 | Yellow. | Red. | Yellow. | Red. | Yellow. | Red. 
 Exterior Varnish....... yy” 42 1.1 36 ia 33 1.3 
 Ext. Varnish 25% Turp..| 14” 32 0.8 30 0.5 28 0.5 
 Ext. Varnish 50% Turp..| 14” 28 0.5 23 0.5 21 0.4 
 Seerioor Varnish.......... 4? 65 ou 62 Oyo 61 3.0 
 _ Floor Varn.+25% Turp.| 14” 52 171 50 1.3 45 1} 
 Floor Varn.+50% Turp.| 1%” 36 0.1 34 0.1 32 0.1 
 Rubbing Varnish....... yy" 42 5.6 43 6.2 46 6.2 
 Rubbing Varn. 25%Turp| 14” ol 4.3 36 4.2 38 4.0 
 Rubbing Varn. 50%Turp| 1%” |... 42 5.0 48 6.0 50 6.0 
 
 The same combination of glasses was used in successive readings to deter- 
 mine whether there had been any change in color. This procedure is necessary 
 because the combined thickness of the glasses affects the reading. For in- 
 Stance, a Sample may match glasses 16+ 14+ 8 but be lighter than a combina- 
 tion of glasses 16+ 14+ 6+2. In the Second and third readings, the same 
 combinations of glasses as were found to match the sample in the first readings 
 were tried. Changes were then made until the glasses matched the samples. 
 In Tables 62 and 63 only total readings are given. 
 
 In considering the set of 12 solutions reported on Table 62, 
 it was found possible to omit samples 3 and 5. This left a 
 series of 10 standards which during the past year have been 
 slightly revised in gradation. Standard No. 1 is now equiva- 
 lent to the Standard for turpentine in accordance with the 
 U. S. Interdepartmental Specifications for that material. 
 Standard No. 9 in the new set is the equivalent of the bichro- 
 mate solution used as the standard in accordance with the 
 Federal Specifications Board Specifications for Spar Varnish. 
 These ten new standards made up as outlined and now con- 
 taining 25 per cent of alcohol to further guard against fer- 
 mentation, are placed in tubes and hermetically sealed. 
 This method of sealing has been found to be the only one that 
 is satisfactory. These tubes are placed in special carrying 
 eases such as that used for the Bubble Viscosity Test Stand- 
 
484 Color Standards for Varnishes 
 
 ards described on page 32. The labels used on the carrying 
 case with methods for use are given below. 
 
 Combination of Glasses in Lovibond 
 Tintometer to Match Sample 
 
 eee aT 
 Solution Size of cell 
 No. inches Yellow Red 
 1 % 0.0 0.0 
 2 VY 0.38 0.0 
 3 % 3.0 1.0 
 4 % 14.0 3.6 
 5 % 17.5 6.0 
 6 % 21.0 20.0+1.0 10.0 
 7 4 15.0 : 8.0 
 8 iy 41.0 12.0+14.0+15.6 12.0 
 9 WY 51.0 15.0+16.0+20.C€ 16.0 
 10 A 56.5 16.5+20.0+ 20.6 34.0 14.04 20.0 
 
 Directions for Using Color Standards.—Fill one of the extra tubes with 
 the sample to be gauged for color. Compare it with the suggested standards. 
 The sample and standard tube being compared should be held close together 
 and observed by transmitted light. Readings of each with the Lovibond tinto- 
 meter are presented. 
 
 No. 1 is approximate to limit of color for turpentine, Federal Specifications 
 Board Specifications, Recommended Standards for Turpentine. 
 
 No. 9 is approximate to limit of color for Spar Varnish, Federal Specifica- 
 tions Board Specifications, Recommended Standards for Spar Varnish: 3 grams 
 potassium bichromate to 100 ce. sulphuric acid Sp. Gr. 1.84. 
 
CHAPTER XXVII 
 -ANALYSIS OF MIXED DRIERS 
 
 While composed mainly of organic material, mixed driers 
 may contain silicon, iron, aluminum, calcium, magnesium, 
 phosphorous, copper, zinc, lead, manganese and cobalt. Some 
 of these are present in linseed oil, oils and resins, some may 
 be accidentally introduced (as from kettles) and some are 
 purposely added. Although the last three only are usually 
 determined, the possible interference of the others must be 
 considered in any scheme of analysis. 
 
 When an accurate determination of the percentage of 
 various metallic driers in oils and varnishes is desired, it is 
 eustomary to slowly ignite the mass and examine the ash. 
 Wet oxidation of such large amounts of sample as are 
 necessary, with nitric and sulphuric acids is impracticable 
 and rapid ignition at high temperatures will result in the 
 volatilization of some or all of elements such as lead and zine. 
 
 The ash is usually extracted with nitric acid, on account of 
 the presence of lead. It is to be borne in mind that direct 
 determination of lead as sulphate is not permissible in the 
 presence of calcium, that the bismuthate method for man- 
 gwanese can not be used in the presence of cobalt, and that 
 most methods for the determination of cobalt require the 
 elimination of several of the above constituents. 
 
 RECOMMENDED PROCEDURE* 
 (For lead, manganese and cobalt) 
 
 Ash 50-200 g. of the drier in a muffle at the lowest possible 
 temperature. Dissolve the ash in dilute nitric acid (1:1), 
 adding hydrogen peroxide to facilitate solution in case per- 
 oxides are present. Filter and dilute to measured volume. 
 
 Determine manganese in an aliquot of the above solution 
 by the persulphate-arsenite method if cobalt is present and 
 by either this method or the bismuthate method in the ab- 
 sence of cobalt. (A. S. T. M. Standards, 1921, pages 514-16.) 
 
 Determine lead in another aliquot by first precipitating 
 with hydrogen sulphide in a solution of suitable acidity, dis- 
 solving the precipitate in hydrochloric acid with the aid of 
 
 * Suggested by P. H. Walker. 
 
486 Analysis of Mixed Driers 
 
 a little nitric acid toward the end, if necessary, and then finally 
 precipitating the lead as sulphate or as chromate by the 
 usual procedures. } 
 
 Determine cobalt in another aliquot by first evaporating 
 with sulphuric acid to eliminate lead, then carrying on a 
 double precipitate with ammonia to eliminate iron and alumi- 
 num, and finally adding potassium nitrite to the combined 
 ammoniacal filtrates after acidification with acetic acid. In 
 ease the amount of cobalt is very small, a preliminary con- 
 centration should be carried out by treating the ammoniacal 
 filtrates with ammonium sulphide, filtering, dissolving the 
 sulphides, making the solution alkaline and then proceeding 
 with the acidification and addition of nitrite. 
 
 If a determination of zinc is desired, it may be carried out 
 in the filtrate from the hydrogen sulphide separation of lead. 
 In this ease, the filtrate should be treated with sulphuric acid 
 and evaporated until sulphuric acid is evolved. The cooled 
 solution should then be diluted, neutralized until it contains 
 approximately one hundredth normal sulphuric acid and zine 
 precipitated in the sulphide which can then be ignited and 
 weighed as oxide or sulphate. For determining the efficiency 
 of a drier, see methods outlined under Federal Specifications 
 Board Specifications for Drier, back of this volume. 
 
 Quick Test for Driers in Varnishes and Pigmented Enamels. 
 —A quick test communicated to the writer by C. L. Schumann,* 
 for determining such constituents, is as follows: 3 
 
 Weigh 50 grams of varnish into a 500 ec. Erlenmeyer flask, 
 add 60 ce. of denatured alcohol, 60 ce. concentrated hydro- 
 chlorie acid, and a few glass beads. Heat on.a hot plate un- 
 til most of the alcohol is boiled off. -Add about 12 oz. of water 
 and heat to boiling, subsequently filling up to the neck of the 
 flask with turpentine substitute. Heat and let stand until a 
 clear separation is noted. Siphon off the turpentine substi- 
 tute and add another portion thereof. Repeat process. Kvap- 
 orate the water solution to a sufficient concentration for de- 
 termining metals present. This water solution will contain 
 all the metal portion of the varnish. The same method as 
 above may be used with enamels, but only 2 or 3 grams is re- 
 quired. i 
 
 *Pratt and Lambert Laboratories, 
 
 ” a 3 Ai te . 
 sc con iene 
 
Analysis of Mixed Driers 487 
 
 Morrell* gives certain qualitative tests for lead, mangan- 
 ese, and cobalt driers in varnish, that are referred to here- 
 with. For detecting the presence of lead, the varnish or 
 drier is diluted with about an equal quantity of light petro- 
 leum ether. A dilute solution of potassium bichromate is 
 added, and the mixture shaken thoroughly. If lead is pres- 
 ent, there will be no sharp line of division between the water 
 and the diluted varnish, owing to the formation of a precipi- 
 tate of lead chromate at the dividing surface, and also on 
 the walls of the test tube. The contents are poured out of 
 the tube and the walls carefully examined for the presence 
 of yellow lead chromate adhering to the sides. The addition 
 of some ammonium sulphide, which will turn the chromate 
 to a dark color, is confirmatory. This test works in the 
 presence of manganese and cobalt. 
 
 For the presence of manganese, 2 or 3 ec. of the varnish 
 are thinned with from 3 to 4 ee. of petroleum ether and 
 shaken for about 8 minutes with moderately dilute nitric acid. 
 The aqueous layer is withdrawn and boiled with a pinch of 
 manganese-free lead peroxide. On settling, a violet color 
 indicates the presence of manganese. This test can be per- 
 formed directly in the presence of lead and cobalt. | 
 
 For the presence of cobalt, the varnish is diluted with light 
 petroleum ether, and then shaken with dilute hydrochloric 
 acid. The water layer is separated, and to it there is added 
 an excess of ammonium sulpho cyanate with a little concen- 
 trated potassium acetate and 2 or 3 drops of saturated tar- 
 taric acid (to remove ferric sulpho cyanate), a blue colora- 
 tion indicating cobalt. If rosin is present, the procedure 
 is slightly modified. 114 ce. of the thinned varnish is shaken 
 with % ce. of ammonium sulpho cyanate solution; 14 ce. amy] 
 alcohol, and from 3 to 4 ec. of ether are added. This mixture 
 is shaken. As a red color might indicate a trace of iron, 1 
 ec. of ammonium acetate solution and 2 or 3 drops of satu- 
 rated solution of tartaric acid are added, whereby the var- 
 nish-ether-amyl alcohol layer becomes green. The addition 
 of 1 cc. of acetone causes a cobalt blue color to appear in the 
 aqueous layer. The presence of lead and manganese does 
 not interfere. 
 
 * Robert S. Morrell, Varnishes and Their Components. Oxford Technical 
 Publications. 
 
CHAPTER XVIII 
 
 EXAMINATION AND ANALYSIS OF VARNISH RESINS* 
 
 The value of a resin for varnish purposes depends largely 
 upon its physical properties, such as color, hardness, and fusi- 
 bility. In certain cases chemical tests, such as acid number 
 and acetyl value, yield important information. Knowledge 
 of the chemistry of the varnish resins, however, is far from 
 complete and their composition, except in two or three cases, 1s 
 not definitely known. Consequently there is much confusion 
 in the literature regarding the proper method of procedure for 
 determining the chemical constants. The purchase of resins 
 on chemical constants such as iodine, saponification, and acid 
 values together with ash, color, and size of lumps may not be 
 far distant. Such procedure would at least eliminate many 
 fanciful ‘‘gradings’’ now existing and which have but little 
 meaning. 
 
 All resins used in varnish making may, for analysis at least, 
 be conveniently divided into two classes: 
 
 (1) Fossil Resins (‘‘Copals’’ or ‘‘ Varnish Gums’’). These 
 are in general very hard and difficultly soluble. They must be 
 melted and held at a rather high temperature until a certain 
 portion is driven off and they become soluble in oil. 
 
 (2) Spirit soluble resins such as rosin, sandarac, mastic, 
 damar, ete. 
 
 These two groups interlap to a certain extent. For instance, 
 Manila which is soluble in alcohol, must be ‘‘cracked’’ at a 
 rather high temperature when used in oil varnishes and for 
 the latter purpose might be considered as a fossil resin. 
 
 PuysicaL CHARACTERISTICS OF Fosstu RESINS 
 
 Hardness.—The term hardness is purely relative. More- 
 over, the value of the resin depends not so much upon its initial 
 hardness as upon the degree of hardness which it imparts to 
 the finished varnish. <A resin of greatest initial hardness, 
 however, usually produces the hardest varnish. The general 
 scale of hardness of the principal types of copal, according 
 to EK. J. Parry,t is as follows: 
 
 *Arranged by the writer and P. C. Holdt, from Scientific Section, Cir- 
 cular No. 159. ; 
 
 yGums and Resins, E. J. Parry, Pitman & Sons, London. 
 
 ~— a 
 
Examination of Varnish Resins 
 
 489 
 
 1. Zanzibar 6. Sierra Leone (fossil) 11. Manila 
 
 2, Mozambique 7. Yellow Benguela 12. White Myola 
 
 3. Lindi 8. White Benguela 13. Kauri 
 
 4, Benguela 9. Camaroon 14. Sierra Leone (liv- 
 5. Pebble 10. Congo ing trees) 
 
 15. South American 
 
 This table agrees 
 gators. 
 
 fairly well with that of other investi- 
 
 The hardness of resins may be measured by means of the 
 methods described in chapter III. 
 
 TABLE 64.—Table Showing Percentage of Resins Dissolved by Various 
 
 Solvents. By Coffignier 
 
 a # Carbon 
 
 Ethyl Amyl Spirits of 2 
 
 Alcohol Ether Alcohol | Turpentine ane p 
 
 eet leo es Soe 14.10 | 25.00 | 36.70 | Insoluble Insoluble 
 0 a 26.20 | 35.00 7P.60 39.70 15.00 
 remneTOrA cw 27.90 | 44.60 | 47.00 7.50 24.50 
 OS A 1421051" 61.70 97.80 31.80 30.90 
 pierra leone. ........0-... 8/40 | 52.20 95.20 28 .60 29.10 
 12 hs Sa 69.80 | 70.30 98 .20 51.80 55.10 
 US Cl 83.50 | 56.30 99.10 31.20 26.00 
 Rn oe... 42.60 | 57.40 91.50 20.40 30.10 
 MeMCTUfig es SG es hoe ss 33.30 | 44.20 | 70.80 21.40 26.30 
 ON 52.20 | 56.00 | 95.90 20.30 19.70 
 GG 93.40 | 38.20 | Soluble 22.50 18.90 
 oe 64.20 | 39.30 | Soluble 26.40 22.70 
 OOS CO 87.70 | 52.70 | Soluble 27.10 28.10 
 OO ONG 44.10 | 41.50 | Soluble 26.80 31.00 
 Mienva, friable.........%. Soluble | 71.30 | Soluble 35.90 38 .00 
 a Soluble | 54.00 | Soluble 33.60 38.09 
 PievANPOlA. 6.2656... .. 84.90 | 72.70 98 .60 30.60 38.70 
 PISO a. Se 62.40 | 48.70 | 93.00 23.00 22.30 
 ees es ec. 83.00 | 50.00 | 95.10 31.30 30.40 
 
 According to Bottler, resins may be tested for hardness by 
 scratching with rock salt. All are seratched; the hardest 
 only with much difficulty. He classifies them in order of 
 decreasing hardness: 
 
 1. Zanzibar 5. Congo 
 2. Red Angola 6. Manila 
 3. Sierra Leone 7. White Angola 
 4. Benguela — 8. Kauri 
 
 For further work on hardness of resins see page 499. 
 
 Solubility.—The solubility of the various resins in different 
 organic solvents has been thoroughly studied and numerous 
 attempts made to develop a system of classification based on 
 
Examination of Varnish Resins 
 
 490 
 
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Examination of Varnish Resins 491 
 ee _.____..._— 
 this property. The solubility of a particular resin varies with 
 its age, handling after collection, etc. The hardest and best 
 varieties are in general the most difficult soluble. Tables 65 and 
 and 66 are taken from K. Dieterich’s ‘‘ Analysis of Resins.”’ 
 For further results on solubility see pages 500 and 598-9. 
 
 Fusibility—None of the resins have sharply defined melt- 
 ing points. The fusing is a continuous process and may extend 
 over a considerable range of temperature, as indicated in the 
 table below. The harder resins require higher temperatures 
 to melt them, and always undergo partial decomposition dur- 
 ing the melting process. Different samples of the same kind 
 of resin often differ considerably in this respect, hence the 
 melting point is of little value in identifying a resin. 
 
 TABLE 66.—According to Coffignier 
 
 Specific Softening | Melting 
 
 Gravity Point Point 
 Re he ee ke we 1.058 at 16° 65° 165° 
 ITEC, nec ee eee PoU5D at 7 45° 95° 
 ERNE es ee hk es ee de 1.066 at 17° 90° 300° 
 Ee Palys. oye et ee 1.061 at 17° 90° 195° 
 Sierra eS, er 1.072 at 19° 60° 130° 
 SI ee ee es Te OGG Ate ey ees oa Live 
 UCM ys Ca svn os ee FO OOD Aes ace ee 150° 
 EE A ee PeUsoratiey oto ee 120: 
 Oa oe 1.065 at 17° 80° 190° 
 0S ESN Sr 1.060 at 17° 45° 120° 
 Nae SU SR 1.037 at 16° 55° 1352 
 Se ee rh a eee a dng w bw eke ctw b Gt [eens ote eee? 100° 
 ee eee ec bake cs Sis else dis ewte abana eke 
 
 | 300 
 
 Specific Gravity.—According to Bottler and Sabin,* specific 
 eravity determinations are very useful in estimating the value 
 of aresin. The specific gravity of the resin in its usual condi- 
 tion and after being freed from contained air is found. The 
 resins showing the smallest differences contain the least en- 
 closed air and are assumed to be more valuable than their 
 opposites. They find that Zanzibar, thus treated at 15° C., 
 gives 1.0621 and 1.0636, the difference being 0.0015. Lindi 
 copal shows a difference of 0.0010; red Angola 0.014; Cama- 
 roon 0.015; Manila 0.059; and Kauri 0.064. 
 
 *Bottler & Sabin, German and American Varnish Making. John Wiley & 
 Sons. Pages 13-14. 
 
492 Examination of Varnish Resins 
 
 A method for specific gravity suggested by Dieterich for 
 rosin and which could be applied to other resins is as follows: 
 
 A series of solutions of common salt, ranging between sp. 
 gr. 1.070 and 1.085 at 15° C., are prepared, and in each of these 
 is placed a few fragments of the colophony under examination, 
 the temperature being maintained constant. The sp. gr. of 
 the solution which retains the colophony in suspension will be 
 the same as that of the substance. In selecting the test pieces, 
 care must be taken to reject any which exhibit cracks, air bub- 
 bles, or impurities. 
 
 CHemicaL Examination or Fossit Resins 
 
 Tschirech and his collaborators, KK. Dieterich and others, 
 have done a great deal of work on the various resins and have 
 collected much data concerning their composition, and chem- 
 ical behavior. According to the majority of investigators, 
 varnish resins consist largely of resin acids (resinolic acids) 
 and neutral substances of unknown composition (designated 
 resenes by Tschirch), with small proportions of volatile com- 
 pounds, ash and impurities. The absence of esters, ethers, 
 anhydrides and lactones (except in the case of rosin) has been 
 fairly well established.* 
 
 According to Tschirch and Stephen, the composition of Zan- 
 zibar copal is as follows: trachylolie acid (Css6HssOs), 80 per 
 cent; iso-trachylolic acid (CssHssOs), 4 per cent; essential oil, 
 9.46 per cent; Alpha-resene (CsHesOs) and Beta-resene 
 (C2HssO4), together 6 per cent; ash .12 per cent; impurities .42 
 per cent. Congo copal, according to A. Engel} has the follow- 
 ing composition: Congo Copalie Acid (C1sH3002) 48 to 50 per 
 cent; Congo-Copalolie Acid (C22Hss04) 22 per cent; Alpha Con- 
 go-Copal Resene, 5 to 6 per cent; Beta Congo Copal Resene, 
 12 per cent; Ethereal Oil, 3 to 4 per cent; Impurities and Ash, 
 4 to 9 per cent. 
 
 For those resins which contain no other saponifiable com- 
 pounds than the free resin acids, it might be expected that the 
 acid number, determined in the usual manner (1. e., by dissolv- 
 ing the resin in a suitable solvent and titrating directly with 
 KOH solution) would be identical with the saponification num- 
 
 re KE. J. Parry, contrary to most other workers, states that all copals contain 
 esters. 
 + Journal American Chemical Society, 1903; Vol. 25, p. 860. 
 
Examination of Varnish Resins 493 
 
 ber. This, however, is not found to be true in practice. The 
 saponification number (indirect acid number) is usually con- 
 siderably higher than the direct acid number. There are prob- 
 ably several contributing causes for this variation. Accord- 
 ing to evidence presented by Worstall* (in a very excellent 
 article on Fossil Resins) when a resin is titrated directly with 
 an alkali solution, the resin acids are neutralized very slowly. 
 There are also indications that small amounts of aldehydes 
 may be present and that these take up alkali during the saponi- 
 fication process, thus giving a higher figure by this method. 
 
 Numerous methods have been proposed for determining acid 
 and saponification numbers using different solvents in varying 
 proportions. Widely varying values have been reported, and 
 much of the literature on the subject is highly contradictory. 
 These differences of opinion are undoubtedly due in some 
 eases to actual variations in the samples examined, many being 
 of doubtful origin. In other cases where there is a wide 
 divergence on apparently authentic samples of the same resin, 
 it is probably due largely to a difference in the method em- 
 ployed. Hence reported values are meaningless unless the 
 method used is specifically described. 
 
 Since many of the resins are insoluble or only partially solu- 
 ble in alcohol, it is in general advisable to use other solvents. 
 Various mixtures of alcohol, benzine, benzol, ether and chloro- 
 form have been suggested. Alcohol alone is suitable only for 
 rosin, shellac, and possibly Manila. 
 
 The presence of water in the solution should be carefully 
 avoided. It will not mix with most organic solvents, but forms 
 an emulsion which makes the titration more difficult by render- 
 ing the end point less distinct. Furthermore, according to 
 Dieterich, the addition of water decomposes the resin soaps 
 and results in abnormally high values. An alcoholic KOH 
 solution should always be employed. 
 
 The following methods of analysis have been used and found 
 satisfactory by the writers: 
 
 Direct Acid Number—Weigh three grams of powdered 
 resin into a 500 cc. Erlenmeyer flask and add 200 ee. of alcohol 
 benzol, Allow the mixture to stand overnight in a tightly 
 stopped flask and then titrate with fifth normal alcoholic KOH 
 
 *Archive der Pharmacie, 1908, p. 298. 
 
494 Examination of Varnish Resins 
 
 solution, using phenol-phthalein indicator. Run a blank on 
 the alcohol-benzol at the same time. 
 
 Both the alcohol and the benzol used as solvents should be 
 redistilled before using. The alcohol passing over at 78 to 
 39° (. and the benzol at 80 to 82° C. being collected for the 
 purpose. 
 
 A fifth normal solution of KOH in C. P. absolute Methyl Al- 
 cohol is used for both acid and saponification numbers. Methyl 
 is preferable to Ethyl Alcohol on account of the difficulty in 
 obtaining the latter sufficiently free from aldehydes to prevent 
 darkening on standing. 
 
 Saponification Number (Indirect Acid Number).—The same 
 quantities of resin and solvent are used as in taking acid num- 
 ber. An excess of alcoholic KOH is added, the flask tightly 
 stoppered, allowed to stand 18 hours and then back-titrated 
 with fifth normal sulphuric acid. <A blank is run on the same 
 quantity of alkali and solvent as used in the determination. 
 
 The saponification number may also be determined by boil- 
 ing the resin-solvent-alkali mixture for 14 hour under a reflux 
 condenser. The solution is cooled and the residual alkali. 
 titrated as before. Saponification numbers determined in this 
 way are somewhat higher than those determined by saponifica- 
 tion in the cold. The solvents and alkali solution for saponi- 
 fieation numbers are made up in the same manner as those 
 used for Direct Acid Number. 
 
 A method recommended by K. Dieterich and used by Wor- 
 stall* with a slight modification in solvents gives very good 
 results. This method is as follows: 
 
 Weigh one gram of the finely powdered resin into a glass- 
 stoppered bottle and add 15 ce. benzol and 5 ee. aleohol. Solu- 
 tion is complete in a few minutes with these solvents. Then 
 add 15 ce. fifth normal alcoholic potash solution and allow to 
 stand 18 hours. Add 25 ec. alcohol and titrate the excess alkali 
 with fifth normal sulphuric acid, using phenolphthalein as the 
 indicator. Blank determinations are run each time. The addi- 
 tion of alcohol before the titration is a great help in securing 
 sharp end reactions. 
 
 Acetyl Value——K. Dieterich proposed the following method 
 for determining the acetyl value of resins: 
 
 * Journal American Chemical Society, Vol. 25 (1903), page 862. 
 
Examination of Varnish Resins 495 
 
 Boil the resin under a reflux condenser with an excess of 
 acetic anhydride and a little anhydrous sodium acetate, until 
 completely dissolved, or until it is evident that no farther 
 portion will pass into solution. Pour the solution into water, 
 collect the ensuing precipitate and extract with boiling water 
 until perfectly oe from all traces of uncombined acetic acid. 
 The insoluble residues left by copal and dammar are also 
 treated in the same manner. The dried acetylized products 
 are then tested for the acetyl, acid, ester and saponification 
 values by dissolving 1 gram in cold Ate tell and titrating with 
 half normal ne potash. The saponification is also Serie 
 with half normal alkali for half an hour under a reflux con- 
 denser, and the product titrated back after cooling and dilu- 
 tion with alcohol (not water). As in the case of fate the dif- 
 ference between the acetyl-saponification value and te acetyl- 
 acid value gives the ‘‘true acetyl value.’’ 
 
 Resins Other Than Fossil.— Under this heading are included 
 the following types of resins: 
 
 (1) Resins ordinarily used as solutions in some volatile sol- 
 vent. Prominent in this group are shellac and macassar which 
 are usually applied in alcohol solution and sandarac, mastic, 
 and damar, which are generally cut in petroleum spirits. tur- 
 pentine or some similar solvent.* 
 
 (2) Rosin. 
 
 (3) Ester Gum. 
 
 (4) Synthetic resins. 
 
 These resins are distinguished from the fossil resins in 
 being softer, much more readily soluble in volatile solvents 
 and having lower melting points. As indicated at the begin- 
 ning of this chapter, however, there ig no sharp line of de- 
 marcation between the classes. For example, both manila and 
 
 macassar might be classed either as fossil or as aleohol soluble 
 resins. 
 
 Acid and saponification numbers can be determined by the 
 Same methods as used for the fossil resins. While most of 
 them are soluble to a certain extent in aleohol more concord- 
 ant results will, in general, be obtained when the resin is dis- 
 
 *Manila might also be placed in this class as it is soluble in alcohol and 
 is frequently so used. 
 
496 Examination of Varnish Resins 
 
 solved in a mixture of alcohol and benzol.* Alcohol alone is 
 entirely suitable as a solvent only for rosin, shellac and ma- 
 cassar. 
 
 Macassar, Sandarac, Mastic and Damar.—These resins are 
 usually evaluated entirely on a basis of color, solubility, size of 
 lumps and freedom from dirt or other foreign material. How- 
 ever, chemical tests such as the determination of acid number 
 are of value in checking up on the uniformity of different 
 shipments. 
 
 Shellac (see Chapter X XIX). 
 
 Ester Gum.—The main consideration in the evaluation of 
 ester gum is, as a rule to secure the lowest possible acid num- 
 ber consistent with good color. Determination of melting point 
 and the degree of darkening occurring during melting are 
 also important indications of quality. 
 
 Ethyl Acetate Test for Ester Gum.—One part ester gum 
 is dissolved in 1 part of ethyl acétate. The solution is placed 
 in the ice box at 0° C. for 72 hours. At the end of that time 
 there should be no precipitate in the vessel. It has been sug- 
 vested by one resin manufacturer that any matter precipitated 
 in this test decreases the adhesive properties, diminishes the 
 gloss and hastens the decay of lacquers and varnishes using 
 ester gum which contains it. 
 
 Yacca Gum (Red Gum; Gum Accroiides)—This product 
 which is quite widely used as a shellac substitute in dark 
 colored compositions, is almost entirely insoluble in benzol, 
 mineral spirits, or turpentine. It is readily soluble in acetone, 
 ether, and alcohol. Distillation under vacuo generally yields 
 a phenol body having a strong phenol odor. For methods of 
 testing shellac see page 526. 
 
 Phenolic Type Resins.—Resins of the formaldehyde-phen- 
 olic type are readily identified by their strong odor of cresylic 
 acid or phenol. Fonrobert (Chem. Ztg., 1922, 46,513) de- 
 scribes the results of tests made on a series of condensation 
 products from various German sources. A study of these 
 results shows the great variety existing In many German 
 products. Steinitzer (AKunststoffe, 1915, 5,109) states that 
 the phenol resins may be detected by boiling with caustic soda 
 
 *Sandarac is practically insoluble in benzol. For analytical purposes hot 
 absolute alcohol is the best solvent. 
 
 Vi 
 5 
 
 < 
 
Examination of Varnish Resins 497 
 
 solution or heated soda-lhme, when phenol is liberated, which 
 may be identified by odor or color reactions. This method 
 would hardly serve to discriminate between phenol-formalde- 
 hyde condensation resins and other resins of a phenolic nature. 
 Redman, Weith, and Brock (J. J. E. C., 1914, 205) gives a 
 method for the determination of phenol in the presence of 
 hexamethylenetetramine and formaldehyde. 
 
 An improvement on Steinitzer’s method has been proposed 
 by Herzog. He observed that the quantity of phenol liberated 
 by the Steinitzer test was small and obtained better results by 
 distilling the powdered sample in a current of nitrogen. 
 Filings of the sample are sifted to yield a fine powder. The 
 latter is placed in a distilling flask with a long side outlet tube. 
 The side tube is bent at right angles so as to extend nearly to 
 the bottom of an Erlenmeyer flask. A current of nitrogen is 
 passed through the distilling flask. By this method, Herzog 
 claims to have recovered phenol equivalent to 4 of the sample. 
 
 A method for the determination of free phenol in synthetic 
 phenolic resins has also been suggested by Morgon and Meig- 
 han (J. J. E. C., 1925, 17, 626). This depends on the meas- 
 urement of the hydrogen evolved after treating with sodium, 
 the phenolic solution produced by extracting the resin with a 
 solvent. 
 
 Coumarone Resins.—Coumarone resins, according to Mar- 
 eusson (Chem. Zeit., 1919, 48, 109 and 122) dissolves com- 
 pletely or almost completely in acetone, while coal tar pitch, 
 lignite pitch, wood-tar pitch, and petroleum pitch are practi- 
 eally insoluble in this solvent. 
 
 Wolff’s method (Farben Ztg., 1918, 23, 307) for the identifi- 
 eation of coumarone resins has been developed and success- 
 fully used by Ellis (‘‘Synthetic Resins and their Plastics,’’ 
 1925, p. 54). The separation from fatty acids is accomplished 
 by saponification, the soaps being separated by boiling with 
 water. ‘The final identification of the resin is made by destruc- 
 tive distillation. Coumarone resin decomposes at 300-400° 
 into coumarone, b. p. 172, indene b. p. 182, hydrindene b. p. 
 176, along with a small quantity of cresols. The presence of 
 coumarone and indene in the distillates is determined by means 
 of their picrates and bromides; coumarone picrate melts at 
 102° C. and the dibromide at 86° C. Indene picrate boils at 
 180° C., while the dibromide melts at 43-45° C. 
 
498 Examination of Varnish Resins 
 
 A more rapid method of determining coumarone in resin 
 is by the color reaction with bromine. Coumarone resins give 
 a permanently red color when treated with bromine in the 
 presence of glacial acetic acid. The test is carried out as 
 follows: 1 cc. of a 10% solution of the resin in chloroform is 
 diluted with 6 ec. of chloroform, and 1 ce. of glacial acetic 
 acid is added. The solution is then shaken and 1 ce. of a 107% 
 solution of bromine in chloroform is added, the solution again 
 shaken, and allowed to stand. A permanent red color devel- 
 ops if coumarone resin is present. 
 
 During the last few years many synthetic resins have come 
 into the varnish and lacquer trades. Some have been made 
 from glycerol and phthalic anhydride, and by condensation 
 reactions with toluol products. Probably the most important 
 class is represented by the Albertol resins produced through 
 reactions between phenol and formaldehyde, usually in the 
 presence of some rosin. This latter type is differentiated 
 from the Bakelite type of phenol resins by their hardening 
 properties in the absence of baking, as well as their solubility 
 
 i 
 \ 
 “Le 
 re. 
 22 
 Pe, 
 ' 
 x 
 * 
 be. 
 a 
 5 
 a 
 es 
 ‘ 
 tas 
 r} 
 
 in oils. The identification of these resins is naturally a diff- . : 
 
 cult matter. A determination of their physical constants 
 gives much more information. 
 
 Testing the Physical Properties and Solubility of Some 
 Synthetic Resins —Some of the synthetic resins of the modi- 
 fied phenol-formaldehyde type, which have recently appeared 
 upon the market are being used to a considerable extent in 
 the production of quick drying varnishes. The main char- 
 acteristic of these resins is the harder surfaces which they 
 produce. This was clearly shown by exposures of exterior spar 
 varnishes made with one of these resins, as compared to a 
 similar varnish made with ester gum. They were applied in 
 thick, flow-coat films to metal panels and exposed upon the 
 roof of the laboratory. The varnish made with the synthetic 
 resins apparently dried to a hard film, whereas those made 
 with ester gum apparently dried only at the surface, the under 
 portion remaining soft. This condition naturally caused the 
 formation of cracking and checking. 
 
 The melting point, acidity, and hardness of these synthetic 
 resins as compared with rosin and ester gum are given in the 
 table below. In determining the hardness of these resins, they 
 were fused and poured into friction top can lids to a depth 
 
499 
 
 Examination of Varnish Resins 
 
 *So]BIS peu 94) UL psoonpoud SB vdA} [OJLOQ TY IY} JO IIB SUISW DAT ISA eG DZ 
 
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 SLINAWIYadX NI GaS{) SNISHY AO SSANGUYVH GNV ‘ALIGIOY ‘“SLINIOQ ONILTAN 
 19 ATAV GE 
 
Examination of Varnish Resins 
 
 500 
 
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 Ne a a Sea Raine aN Dna A, OP aU eae Il) OS OL saa Lara MS TR ea ate Via Cimon Pe Se wT 
 
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 CD $7.02) TANLVUAAINAL WOO LV SLNYATOS SNOTYVA NI SNISAY AHL AO ALITIGNIOS 
 
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 re x Ee ee ee 
 
Examination of Varnish Resins 501 
 
 of about 3/16 inch. Upon cooling, the determination of hard- 
 ness was made with a swinging beam, in accordance with the 
 outline given on page 74. This method, of course, is subject 
 to improvement. 
 
 The solubility of the synthetic resins referred to above was 
 determined, and is given in Table 68. Determination was 
 made by adding an excess of resin to the solvent, and heating 
 the mixture. Upon cooling, the clear mixture was removed 
 from the suspended matter, a portion weighed and evaporated, 
 and the amount of non-volatile thus determined. This gave 
 information as to the amount of resin that could be held in 
 solution by any of the solvents used, at a temperature of 20 
 to 20 degrees C. Wherever the figure 100+ is given, it indi- 
 cates that the solvent referred to will hold in solution, at the 
 temperature given, at least 100 per cent of the resin experi- 
 mented with. 
 
502 Examination of Varnish Resins 
 
 EXPOSURE TESTS ON RESINS 
 SERIES A. 
 RESIN SOLUTIONS. 
 
 50 parts by weight Resin, 50 parts by weight Toluol (or other solvent noted.) 
 Panels exposed Feb. 24, 1927. 
 
 Rating on 
 April8 May 24 General Observations 
 
 ae a nnn neces 
 
 Fine checking in 1 month. Heavy 
 
 Ampberol “BiSsli.is% te 5 4 chalking and loss of gloss after 3 
 months. 
 
 Fine checking in 1 month. Heavy 
 
 Amberol: 7.5.05. 535% 4 4 chalking and loss of gloss after 3 
 months. 
 
 . Chalking after 1 month. Rusts through 
 
 Amberol: HAO. 0s 25 ewe see 5 2 film in 2 monte 
 Some loss of gloss and slight chalking 
 Condensation No. 1...... 10 8 after 2 months. Film checked but 
 
 no rust after 3 months. 
 Entire surface covered with rust in 5 
 
 1 s » ‘ 
 Condensation No. 2...... 0 0 days. Failed. 
 ‘ CS Chalking and fine checking in 6 weeks. 
 Ran CONnZO.s Pes eee 5 a Rust under film’ in 12 weeks. 
 AS : Chalking after 4 weeks. Very heavy 
 Tadeht Cumays.. 5:08 ate + 4 chalking at end of 12 weeks. 
 ‘ : Rust through film in 5 weeks. Covered 
 Damar Batavia......... 4 2 with rust in 12 weelee 
 Damar Singapore (alco- Ghalking in 8 weeks. Heavy rust under 
 DOLD-A4 soe Wee oe age 8 4 film but film intact after 12 weeks. 
 Retar (1 Fine checking and chalking in 4 weeks, 
 i ee leet Be A Since 2 2 Rusts through film in 12 weeks. 
 Hexol G (2 resin—1 - Fine checking in 5 weeks. Some rust 
 toluol—1 alcohol) .... 10 vé through film in 12 weeks. 
 Alligatoring and chalking after 4 weeks. 
 Hesol) R-205¢6 sa wees eee 1 0 Rusts through film after 12 weeks. 
 Failed. 
 j Fine checking and chalking after 4 
 Rey vs fal Secs ake ee 3 1 weeks. Rusts through film after 12 
 weeks. 
 Chalking after 4 weeks. Rust under 
 Manila “(Caleonol j-3..<.4.< 3 2 film and heavy chalking at end of 
 12 weeks. 
 Fine checking and chalking after 4 
 Pontianak (alcohol) ... 3 1 weeks. Rust through film in 12 
 weeks. 
 Fine checking, slight chalking after 4 
 Rosin (Refined Wood) .. 3 1 weeks. Rusts through film in 12 
 weeks. 
 Fine checking, slight chalking after 4 
 Rosin (W.W Gum Rosin) 3 0 weeks. Rusts through film in 12 
 
 weeks. Failed. 
 
 0 Fine checking but fair gloss in 4 weeks. 
 
 tlycerol-Phthali Si 
 Glycero halide Resin 2 Rusts through film in 6 weeks. Failed. 
 
 SR ee ERC ee Me ee SOR Ne ce eg Aebeerjceg een niimeniiaill 9 
 
Examination of Varnish Resins 503 
 — 
 SERIES B. 
 
 RESIN AND OIL SOLUTIONS. 
 Resin solutions of Series A extended with oil. Oil used was heavy bodied 
 linseed oil dissolved in an equal volume of toluol. 5 parts of 
 resin solution A and 1 part of oil solution. 
 Panels exposed Feb. 24, 1927. 
 
 Rating on 
 April8 May 24 General Observations 
 Fine checking in 4 weeks. Rust under 
 mE werot bs, 1 ..e sk... 8 6- film in 6 weeks. Rust under film in 
 12 weeks. 
 Binverag, N-f ........... 9 7* Checking. Some rust. Dull in 6 weeks. 
 oe - 2S 0 gq Heavy chalking and some’ rust through 
 
 film in 4 weeks. Failed. 
 
 ‘ c hilm intact. Rust in oil craters after 
 Condensation No. 1 ..... 8 tf toeweeks 
 PGienvation No. 2 7 5 Slight rust under film after 8 weeks. 
 
 Film sound after 12 weeks. 
 
 Slight chalking after 4 weeks. Heavy 
 PUT ONLO So... ks eae bi) ae chalking but film fairly sound after 
 12 weeks. 
 Slight chalking after 6 weeks. Heavy 
 ate ADUINGY os oe es ss 5 D chalking but film fairly sound after 
 12 weeks. Dark color. 
 
 Fine checking in 4 weeks. Heavy 
 
 ‘ chalking and rust under film in 8 
 Damar Batavia ......... 8 2 weeks. Rusts through film in 12 
 weeks. 
 Fine checking in 4 weeks. Heavy 
 Damar Singapore (alco- chalking and rust under film in 8 
 US 8 2 weeks. Rusts through film in -12 
 weeks. 
 Covered with fine checking after 4 
 Oo ET rrr o 0 weeks. Heavy chalking and rusts 
 through film in 8 weeks. Failed. 
 Hexol G (2 resin—1 Chalking and some rust under film in 
 toluol—1 alcohol) .....10 7 12 weeks. Film sound: 
 Chalking after 4 weeks. Rust under 
 OO 0 0 film in 6 weeks. Rusts through film 
 in 12 weeks. Failed. 
 Fine checking and chalking in 4 weeks. 
 OS 0 0 Rust under film in 8 weeks. Rusts 
 through film in 12 weeks. Failed. 
 ; Fine checking and chalking after 4 
 Manila (alcohol) ....... 4 3 weeks. Rust under film after 6 weeks. 
 Fine checking and chalking after 4 
 Pontianak (alcohol) .... 3 0 weeks. Slight cracking and rust 
 
 under film after 8 weeks. Rusts 
 
 through film after 12 weeks. Ki 
 Checking, chalking and rusting after 4 
 Rosin (Refined Wood) .. 0 0 weeks. Rusts through film after 6 
 weeks. Failed. 
 
 Checking, ‘chalking and rusting after 4 
 
 Rosin (W.W.Gum Rosin) 0 0 weeks. Rusts through film. after 6 
 weeks. Failed. 
 Glycerol-Phthalide Resin 7 9 Checking but fair gloss after 4 weeks. 
 
 Rusts through film in 6 weeks. 
 * Pitted in spots where separation occurred. 
 
504 Examination of Varnish Resins 
 hetoell eae nme ecnieieaneniriae Cia MR 
 
 SERIES C. 
 
 LACQUER-RESIN SOLUTION, 
 
 A standard lacquer base was made of 100 parts by weight of 32 oz. Butyl 
 
 Acetate Solution of 1% second Nitrocellulose, 50 parts by weight of toluol, 
 
 and 5 parts by weight of tricresyl phosphate. To 155 grams of this solution, 
 
 GO grams of resin solution, such as were used in Series A, were added. 
 Panels exposed Feb. 24, 1927. 
 
 Rating on 
 
 April8 May 24 
 
 AMDGPOLIE Se kote oe ee 7 
 Amberol F-71703 Guacasae 8 
 Amberol HeO 4.27 7h wise re 
 Condensation No. 1 ..... 9 
 Condensation No. 2 ..... 9 
 Ran One 0 en soo wie aes 7 
 Light Comarces 5...) wines +) 
 Damar Batavia ....... 10 
 
 Damar Singapore (alco- 
 
 TG] peas wee ect ae 10 
 Ester Gut wasscc owiehe Z 
 Hexol G (2 resin—1 
 
 toluol—1 alechol) .... 10 
 Hevolh Ress oe ce ee 0 
 Rin RAWels. oes eee 3 
 Manila: (aleonol) =... 5.6 4 
 
 Pontianak (alcohol) .... 5 
 
 Rosin (Refined Wood) .. 90 
 Rosin (W.W. Gum Resin) 0 
 
 Glycerol—Phthalide Resin § 
 
 3 
 
 4 
 
 0 
 
 ° 
 
 General Observations 
 
 Slight spotting and rust under film 
 after 4 weeks. Rust through film 
 after 8 weeks. 
 
 Slight spotting and rust under film 
 after 4 weeks. Rust under film but 
 film still sound after 8 weeks. 
 
 Spotting and rust under film after 4 
 weeks. Rust through film after 8 
 weeks. 
 
 Rusts through film after 12 weeks. 
 
 Rust under crystals in 4 weeks. Rusts 
 through film in 12 weeks. 
 
 White spots on surface and rust under 
 film after 4 weeks. Rusts through 
 film after 6 weeks. 
 
 Rust under film after 4 weeks. Heavy 
 chalking but film sound after 12 
 weeks. Dark color. 
 
 Slight rust under film in 6 weeks. 
 Peeling after 8 weeks. Covered with 
 rust after 12 weeks. Failed. 
 
 Slight rust under film in 6 weeks. 
 Peeling after 8 weeks. Covered with 
 rust after 12 weeks. Failed. 
 
 Rusting under film after 4 weeks. 
 Heavy chalking and rust through film 
 in 8 weeks. Failed. 
 
 Rusting under film after 4 weeks. 
 Heavy chalking and rust through 
 film in 8 weeks. Failed. 
 
 Film failed at the end of 4 weeks. 
 
 Slight rust under film after 4 weeks. 
 Heavy rust under film, heavy chalk- 
 ing, but film intact after 12 weeks. 
 
 Rust accumulating under film after 4 
 weeks, which finally breaks through 
 film after 12 weeks. 
 
 Rust accumulating under film after 4 
 weeks. Rust breaks through film 
 after 12 weeks. Failed. 
 
 Rust through film after 4 weeks. 
 Failed. 
 
 Rust through film after 4 weeks. 
 Failed. 
 
 Film peeling after 6 weeks. Rusts 
 through film after 8 weeks. Failed. 
 
505 
 
 h Resins 
 
 Is 
 
 Examination of Varn 
 
 ‘SSO[S pooyy ‘“SulyVp iy SIS 
 *suUIYIIYI IQ BIBPISHOD— Uo puo0g 
 
 SAV LT YADAV 
 Gua TIVA UANOOVT NI NISAY 
 
 PST quo oLy 
 ‘SSO[S POOK) “SuTypaqo deeq—wuorrpuog 
 
 ‘SAVC L YUALAV GAAIIVA TIO 
 HLIM GHAONHLXG HSINUVA LIYIds 
 
 NISGY HAlTIVHLHd-IOUROATD 
 
 ‘SSOIS pooy “Wy MOTaq 
 ISNI V[CBIIPISUOD = “payooyO—'uoripuog 
 
 ‘SAV 6 YALAV 
 daa TIVa HSINUVA LIvIds 
 
ish Resins 
 
 Examina 
 
 506 
 
 tion of Varn 
 
 [BJU 
 oq} 0} SuLeypB I]S WY Jo sJususeAy IB] 
 -NSUBII] [TRUS [JIM paleAod SUTEq sDUBlTVq 
 ay} “BaIv 9} J[BY-9UO IBAO [BJO V1Bq SUT 
 -Ave] ‘pojdnastp A[peq WIly—wo1z7puog 
 
 ‘SAV LI UALAV 
 GW1IVA WANOOVI NI NISGUY 
 
 fe > Sera OT I OR ee 
 
 GOT ANAT 
 
 ‘Syoeqo uly 
 ‘SyooyO OUTT[BISAIO YJLAK PoovpAojUL ATOITUa =-[B}JSL1O UY AIOA YITA PodBIAL9}UT Ajaarjue 
 
 WIJ WNI ON ‘sso[s pooy—uolipuoyg WITT ‘ySsSnt ON ‘[[NpP vovjang—woripuog 
 ‘SAV 8 MALAV GATIIVA TIO ‘SAVC LT YALAV 
 HLIM GQHANULXH HSINYVA LIUIds GaWTIVA HSINUVA CINIds 
 
 VIAVLIVd UVNNVAd 
 
507 
 
 f Varnish Resins 
 
 Examination o 
 
 ‘sjyutod poqyesailses UT 
 Wy POsteI JO SUOTIIS AB[NSUBII] SUTIABVT 
 ‘TBjou Woy AVMB PoTBos AT[RIARd pue 
 pexyoseqo Alpeq AatoA UWYLy—woirpuog 
 
 ‘SAV OT UADCAV 
 GaTIVa YANOOVI NI NISAUY 
 
 OST aNOdIA 
 
 ‘puUunoIsyOVq TayIVp SUTATAIAO 
 Io[od Joque snbedo Ue potinsse sey wy 
 PpoyV,T “SULp~IYyO PadVl[19JUL YIM pod1dAood 
 AjoItjUe WII] ‘“Sso[s ALB Y_——wolpuog 
 
 ‘SAVG L YALAV GH TIVA TIO 
 HLIM GQHAUNHOXH ASINUVA LIYIdS 
 
 ‘UISOL 
 jo sjTejshao OJUT PoIdnAsIp WIT ‘syooyo 
 oug YIM PIIIAOD sdvJINg—uUoOIIpUoy 
 
 ‘SAV OT UALAV 
 Ca TIVA HSINUVA LIYIdSs 
 
 WAS YUALSa 
 
ish Resins 
 
 f Varn 
 
 10n oO 
 
 rs 
 
 Examina 
 
 508 
 
 yw 5 al Pad + ree == ha, + Ve - 
 
 “UOTJIPUOD 
 poos A[aAVjei Ul 818 SReIe Surpuno.sins 
 YABC “LOTOO JUST] JO 91B YOIYM pue onbdoeyT 
 woody Uns JO uoTyVaedas oyIT Teedde ory 
 suotjdniia podeys-asesnes pue [eotreyds 
 I[BUIS YIIM pPd19AOD VdBJANg—wUOWMpUOY 
 
 ‘SAV OT UADAV 
 aW11VA YUANOOVI NI NISAY 
 
 ae a fi ee. OD ee — 
 
 IST auooLT 
 
 ‘SULYOIYO PaR[A9}UT ou AII A 
 
 “‘SULyOeYO 
 ‘OBJANS IDAO [[B Sjods v}ITA—wolppuog 
 
 SIG “SuryreyD ‘Tup 419a4A—wowrpuog 
 
 ‘SAV 16 YALAV 
 awWiiIVa HSINYVA LIYIds 
 
 ‘SAV Le UALAV GWTIVA TIO 
 HLIM GQHONGULXH AHSINUVA LIYIds 
 
 VTIINVIN 
 
Examination of Varnish Resins 509 
 
 CRYSTALLIZING CONDENSATION RESIN INC) 
 
 SPIRIT VARNISH EXTENDED WITH RESIN LACQUER FAILED 
 OIL FAILED AFTER 18 DAYS. AFTER 16 DAYS. 
 
 Condition.—Surface covered with raised Condition.—Surface covered with needle 
 
 spherical masses of white crystals in con- shaped crystals radiating out from erystal- 
 trast with dark background of metal. lizing points. 
 
 FIGURE 188 
 
 RUN CONGO 
 
 SPIRIT VARNISH FAILED SPIRIT VARNISH EXTENDED WITH 
 AFTER 4 DAYS. OIL FAILED AFTER 4 DAYS. 
 Condition.—Film covered with what ap- Condition.—Surface checking of a broad 
 
 pears to be raised surfaces in the form order shown. Line in photomicrograph is 
 
 of hexagonal checks. Very slight rust. one side of a check. Fair gloss. 
 Good gloss. 
 
 FIGURE 189 
 
510 Examination of Varnish Resins 
 OS 
 Color Comparison of Resins.—For comparing the color of 
 rosin. there is available a set of standard color cubes which 
 may be obtained from Harris N. King, Naval Stores Inspec- 
 tor, Savannah, Ga. It is believed the price is about es 00. A 
 
 FIGuRE 190 
 
 Apparatus Used by Pfister in Making Resin Standards. 
 
 method of making standards of a somewhat different char- 
 acter, for comparing the color of various resins, has recently 
 been evolved by K. Pfister* who has forwarded the following 
 description of his method: 
 
 Various methods have been proposed for measuring the 
 depth of color of resins, e. g., the use of standardized solutions 
 of Potassium Chromate and Bichromate, solutions of Iodine 
 in Potassium Iodide, ete. These methods are in general satis- 
 factory and allow of a comparatively accurate measurement 
 
Examination of Varnish Resins 511 
 
 in terms of numerical scales, and we have found the use of 
 such methods essential where small differences in color must 
 be accurately measured. 
 
 It was also necessary, for our purpose, to be able to measure 
 the color of resins in terms of some widely recognized scale, 
 and by a method the technique of which should be relatively 
 simple. The Standard Rosin Types, although they admittedly 
 possess defects for this purpose, naturally suggested them- 
 selves, on account of their wide recognition, as the most suit- 
 able scale. The method employed for making comparisons 
 is as follows: 
 
 Fight gms. of the sample of resin, in small pieces, is placed 
 in an inverted Aluminum screw cap, as supplied with the 
 standard 4 oz. friction top bottle, and the cap placed on a wire 
 gauze ona tripod. A piece of wide glass tubing is fitted into 
 the serew cap so as to form a funnel and a stream of CO2 run 
 in. The sample is then melted with a Bunsen flame until it has 
 fused to a clear mass. It is allowed to cool in an atmosphere 
 of COz, until the Aluminum ean just be handled. The base of 
 the screw cap is then removed by filing the edges with a steel 
 file. This leaves a transparent circular disc of resin of con- 
 venient and uniform thickness. By removing the base, as sug- 
 gested, before it has completely cooled, shattering of the dise 
 is avoided. The disc can then be compared with similar discs 
 prepared from Standard Rosin Types. By placing two discs 
 alongside each other over white paper and by examining by 
 transmitted light, satisfactorily accurate comparisons can be 
 made. Considerably more accurate comparisons can be made 
 with these discs than with the cubes prescribed for the official 
 Rosin Types. 
 
 Toluol Insoluble Clarity Test for Rosin.—Methods for the 
 determination of the clarity of rosin (freedom from dirt, 
 wood chips, bark, ete.) have been studied by a special com- 
 mittee of Committee D-1 of the A. S. T. M. These methods 
 have been investigated in this laboratory and in other labora- 
 tories with results which check very closely, and have been 
 recommended for adoption by the Society. They are pre- 
 sented below: 
 
 Laboratory Handling of Sample.—Immediately before the 
 determination is to be made, powder the sample to pass a 10- 
 
512 Examination of Varnish Resins 
 
 mesh sieve, mix thoroughly, and place in a wide-mouth bottle 
 which is filled thereby. 
 
 Determination.—Place 50 grams of the freshly powdered 
 sample in a 300 ee. beaker and add 150 ce. of toluol, free from 
 water and non-volatile residue. Dissolve the sample with the 
 aid of heat and occasional shaking. When solution is appar- 
 ently complete (no particles of rosin visible) filter at once 
 through a 25 ce. porcelain Gooch crucible which has been 
 previously prepared with a mat of pure well-washed asbestos 
 such as is used for the determination of BaSO,, and which has 
 been finally washed thoroughly with the solvent used, dried in 
 a boiling water oven for % hour, cooled in a dessicator and 
 weighed. If the rosin filtrate is not clear return it through 
 the Gooch until clear, finally washing the residue and the 
 outside of the crucible free from rosin with additional hot 
 solvent. Dry to constant weight at 105-110° C. (one hour 
 usually suffices), cool in a dessicator, weigh, and calculate the 
 percentage of toluol insoluble. 
 
 Softening and Melting Points of Rosin.—Satisfactory meth-, 
 ods of determining the softening and melting ;points of 
 rosin have been studied by a special committee of Commit- 
 tee D-1 of the A. S. T. M. As yet, these methods have not 
 been adopted. In this laboratory they have given in general, 
 excellent results. They are presented below, merely as a 
 matter of general interest and to stimulate further work in 
 this direction. 
 
 DEFINITIONS 
 
 Softening Point.—The temperature at which powdered rosin 
 in a melting point tube begins to darken and coalesce. 
 
 Melting Point.—The temperature at which powdered rosin 
 in a melting point tube loses its powdered or crystalline shape 
 and becomes wholly transparent. 
 
 APPARATUS 
 
 Thermometers must be accurate, graduated in degrees Cen- 
 tigrade from 45 to 100 and have a length of about 5% inches 
 (137 mm.) and diameter of about 44 inch (6 mm.). 
 
 Test Tubes % by 6 inches (18 by 150 mm.) are fitted with 
 eorks grooved at sides to permit air circulation and bored at 
 center to receive thermometer. 
 
 Melting Point Tubes of thin glass, inside diameter 1/16 
 inch.(1.5 mm.), length about. 2 inches (50 mm.) and closed 
 at one end. 
 
Examination of Varnish Resins 513 
 
 Flasks are ordinary Erlenmeyer type of 300 cc. capacity, 
 the mouths of which must be at least 1 inch (25 mm.) diameter 
 and fitted with a cork grooved at sides to permit air circula- 
 tion and bored at center to receive test tube. 
 
 DETERMINATION 
 
 Place 250 ec. glycerine in the flask, insert the grooved cork 
 earrying test tube so that its lowest point is % inch above 
 the bottom of the flask and heat the flask so that the ther- 
 mometer rises at the rate of 1° C. per minute. 
 
 From the freshly broken surface of a lump of the rosin 
 quickly powder a sample (1-2 grams) and at once fill 4 melt- 
 ing point tubes to a depth of about 10 mm. lightly packing 
 with a fine glass rod or by tapping. Pass the stem of the 
 thermometer through a cork, grooved to permit air circulation. 
 Attach two of the filled melting point tubes to the thermom- 
 eter so that the rosin is opposite the bulb. When the tem- 
 perature of the glycerine in the flask reaches 45° (. place the 
 
 -thermometer and m. p. tubes in the test tube so that the bottom 
 of bulb is % inch above the bottom of the test tube. Continue 
 to heat the flask at the rate of 1° C. per minute, note and re- 
 cord the temperature at which the rosin begins to darken and 
 coalesce (softening point) and also the temperature at which 
 the rosin loses its powdered or crystalline appearance and be- 
 comes wholly transparent (melting point). It is necessary 
 during a test to have a light behind the flask, daylight or 
 electric light. Repeat the test, using the other two filled melt- 
 ing point tubes, making sure that the glycerine bath is below 
 49° C. at the start. 
 
 The four tests of melting point must not vary more than 1° 
 C., otherwise two additional tests must be made and the aver- 
 age reported. The softening point tests will probably vary 
 more than the melting point tests. Report the average of 
 each set of results as the softening point and melting point 
 respectively. 
 
 Some results on samples of rosin as obtained at this labora- 
 tory by the above methods, are given below: 
 
 OE, o. sc once svc en conv cieway 00°C d9°C 
 57 58 
 54 59 
 53 57 
 56 
 60 
 Mean 55°C 58°C 
 
514 Examination of Varnish Resins 
 
 Melting Point 2, ...ceccccnsesssecscesercs 63.0 68 
 62.0 «64 
 
 62.0 65 
 
 62.5 64 
 
 63 
 
 65 
 
 Mean 62.5 65 
 
 Drip Method for Melting Point of Rosin——Another method 
 experimented with by the committee was the drip method. 
 This is outlined below. The drip method will probably give 
 results in various laboratories which will check closely, but 
 the results are usually about 15° higher than by the capillary 
 
 method. 
 DEFINITION 
 
 Melting Point.—The temperature at which the elongated 
 drop of rosin from the thermometer bulb touches the bottom 
 of the test tube. 
 
 APPARATUS 
 
 Thermometers.—Use an A. 8. T. M. Flash Test Thermom- - 
 eter. Range —5° to +110° C. Total length 277-282 mm. 
 Bulb length 9-13 mm., bulb diameter not greater than 6-7 mm. 
 
 Test Tubes.—22 x 180-200 mm. fitted with corks grooved at 
 sides to permit air circulation and bored at center to receive 
 the thermometer. | 
 
 Beakers.—Low or ordinary 600 ee. beaker. 
 
 DETERMINATION 
 
 From the freshly broken surface of the rosin remove a 
 sufficient quantity to fill an 18 mm. diameter test tube to a 
 depth of about 40 mm. Place the test tube in a boiling water 
 bath until the rosin becomes fluid enough to adhere in a film 
 on the thermometer. Heat the previously weighed thermom- 
 eter to 100° C. by immersion in a bath of boiling water, 
 quickly wipe dry, and dip into the rosin to a depth of 15 mm. 
 from bottom of bulb, securing a coating which weighs when 
 eold .50 to .55 gm. and is uniformly distributed. It will prob- 
 ably be necessary to shape the rosin with the fingers. Cool 
 the film rapidly, taking care that it remains evenly distributed, 
 and allow to rest 10 minutes after cooling to room tempera- 
 ture. Fill the beaker to a depth of 90 mm. with water at 
 not over 45° C. Pass the thermometer through the cork and 
 insert in the test tube so that the bottom of the bulb is 25 mm. 
 above the bottom of the test tube. Fix the test tube in the 
 
Examination of Varnish Resins 515 
 
 beaker of water so that the lowest point of the test tube is 
 25 mm. above the bottom of the beaker. Heat the water 
 so that the thermometer rises at not more than 2° (. per 
 minute up to 65° C. and at a rate of 1° C. per minute above 
 65° C. The average temperature in 4 tests at which the 
 rosin dropping from the bulb of the thermometer touches the 
 bottom of the test tube is recorded as the melting pomt (drip 
 method). Ifthe variation of the 4 determinations is greater 
 than 1° C. an additional determination shall be made and the 
 average of the five determinations reported as the melting | 
 point (drip method). 
 
CHAPTER XXIX 
 
 SHELLAC ANALYSIS 
 
 Many developments in connection with the analysis and 
 testing of shellac have taken place during the past three years. 
 Committees of experts representing importers and consumers 
 have now arrived at specifications which have been adopted 
 by the A. S. T. M. These specifications are presented below, 
 including methods of test covering the raw material and shel- 
 lac varnishes. Following these, there is presented the Steele 
 modification of the McIlhiney method for the determination 
 and estimation of adulterants in shellac varnish. This meth- 
 od, which has been used at this laboratory for several years, 
 is fairly rapid and has proved useful. Information is also 
 presented on a method of determining the darkening of cut 
 shellac. 
 
 A. 8. T. M. STANDARD SPECIFICATIONS FOR 
 ORANGE SHELLAC 
 
 1. Orange shellacs may, for convenience, be grouped into the four follow- 
 ing grades: Grade A, Grade B, Grade C and Grade D. Stick, seed, garnet 
 and button lacs are not included under these grades. 
 
 I. PROPERTIES 
 2. Orange shellac shall conform to the following requirements: 
 
 GRADE A GRADE B GRADE C GRADE D 
 
 Iodine number, maximum...........+.- 18.0 18.0 18.0 24.3 
 Matter insoluble in hot 95-per-cent alco- 
 
 hol, maximum per cent...........+ 1.75 2.50 3.00 3.00 
 Moisture and volatile matter, maximum, 
 
 per. Cent Waal ae. ees ee 2.0 2.0 2.0 BY 
 Matter soluble in water, maximum per 
 
 CONC vs CLEA heats ee ron ae nes 0.5 0.5 0.5 0.5 
 Wax, maximum, per cent.............- 5.0 5.5 5.5 5.5 
 Ash, maximum, per cent.........0+-+++ 1.0 1.0 1.0 1.0 
 
 II. SAMPLING 
 
 3. (a) Only original packages shall be sampled. 
 
 (b) Samples-shall be drawn by hand, or a suitable tryer may be used, pref- 
 erably from not less than 10 per cent of the lot. 
 
 (c) In sampling “free” shellac, approximately double handfuls shall be 
 drawn from each bag and quartered down to approximately 2 lb. The shellac 
 shall then be ground to pass through a No. 20 sieve (840 micron opening), half 
 of which shall be reserved by the buyer, the other half used for analysis. 
 
 (d) In sampling “blocky” or “matted” (hard) shellac, about 1 Ib. from 
 each bag sampled shall be ground to pass a j-in. sieve. This shall then be 
 
Shellac Analysis 517 
 
 quartered down to approximately a 2-lb. sample which shall be ground to pass 
 through a No. 20 sieve (840 micron opening) and divided as in sampling 
 “free” shellac.* 
 
 III. METHODS OF TESTING 
 
 4. The determination of iodine number, matter insoluble in hot alcohol, 
 moisture and wax shall be made in accordance with the Standard Methods 
 of Testing Shellac (Serial Designation: D 29) of the American Society for 
 Testing Materials,y and the Standard Method of Test for Determination of 
 
 5. The determination of matter soluble in water shall be made as follows: 
 
 Weigh 10 to 25 g. of the sample accurately and stir thoroughly with 100 ce. 
 of distilled water in a suitably sized flask or beaker. Cover with a watch glass 
 and allow to stand at room temperature (approximately 21°C.) for four 
 hours, stirring occasionally. Decant the water through a 12.5-cm. filter paper 
 into a weighed evaporating dish, washing the shellac and paper with at least 
 50 cc. more of water. Hvaporate the water and dry the extract at 105 to 
 110° C. for one hour or more to constant weight. Cool, weigh, and calculate 
 the percentage of matter soluble in water. 
 
 6. The determination of ash shall be made as follows: 
 
 Approximately 2 to 3 g. of the sample shall be accurately weighed, trans- 
 ferred to a weighed porcelain or platinum crucible and ignited at as low a 
 temperature as possible until all organic matter has been destroyed. The 
 crucible and contents shall be cooled and weighed and the percentage of 
 ash calculated. 
 
 EXPLANATORY NOTES 
 
 In general, Grade A will include grades of shellac known in the trade as 
 D.C., VSO, Diamond I, Double Triangle G and Superfine. 
 
 In general, Grade B will include the grades known in the trade as Fine, 
 Good and Heart Brands. 
 
 Grade C represents the grade known in the trade as Pure TN. 
 
 Grade D represents the grade known in the trade as U.S.S.A. TN, and 
 which may contain up to 3 per cent of rosin. 
 
 A.§8. T. M. STANDARD METHODS OF TESTING SHELLAC 
 DETERMINATION OF MATTER INSOLUBLE IN HOT ALCOHOL 
 
 (a) Continuous Extraction Method (suitable for all grades of lac.) 
 
 APPARATUS 
 1. The extraction apparatus (Fig. 191) shall consist of a wide-neck flask in 
 which is suspended a metal return condenser. From the lower part of this 
 condenser is hung a siphon tube of Knoefler type. The extraction cartridge 
 used for the determination shall be cut down to such a size that the top of 
 
 *The above is a brief abstract of the Rules and Regulations of the United 
 States Shellac Importers Association. 
 
 71924 Book of A.S.T.M. Standards. 
 Wax in Shellac (Serial Designation: D 29) of the American Society for 
 Testing Materials. 
 
 ¢A.8.T.M. Standards Adopted in 1925. 
 
518 Shellac Analysis 
 
 the cartridge is just above the upper curve of the siphon. It shall be supported 
 on three indentations in the glass so that there will be a little space beneath 
 and around the cartridge to permit of a free flow of liquid. 
 
 Nore.—Any type of siphon extractor where the siphon is continuously sur- 
 rounded by the vapors of boiling alcohol may be substituted for the above form 
 of apparatus. 
 
 SOLUTIONS REQUIRED 
 2. 95-per-cent Alcohol.—Specially denatured alcohol, U. 8. Internal Revenue 
 Bureau Formula No. 1 or Formula No. 30. 
 
 METHOD 
 
 3. Prepare an extraction cartridge 26 mm. in diameter by 80 mm. in height 
 (Schleicher and Schull No. 603 or the equivalent). Place the cartridge in the 
 extraction apparatus, Fig. 191, and extract for 30 minutes with boiling 95- 
 per-cent alcohol. 
 
 Dry in an air bath at 105° C., transfer to a glass-stoppered weighing bottle, 
 cool and weigh. Dry to constant weight. A number of cartridges can be 
 prepared and kept in glass-stoppered weighing bottles until wanted. Now 
 weigh accurately 5 g. of the lac in a 100-cc. beaker and dissolve in 75 cc. of 
 boiling 95-per-cent alcohol by immersing the beaker in a hot water bath until 
 all the shellac is dissolved and the wax is in solution. Transfer this solution 
 quickly into the weighed extraction cartridge, previously wet with hot alcohol, 
 putting the cartridge into a carbon filter tube of suitable size supported in a 
 hot water bath (Fig. 192), the outlet tube extending through the bottom of the 
 bath allowing the escape of the filtrate. ° Wash all the residue from the beaker 
 into the cartridge with hot 95-per-cent alcohol. Put the cartridge in the ex- 
 traction apparatus (Fig. 191), and extract for exactly one hour. 
 
 —_— 
 
 ¢ 
 
 Foal Fearne 
 
 FIGguRE 191 
 Extraction Apparatus for Alcohol-Insoluble Matter in Shellac 
 
Shellac Analysis 519 
 
 Keep the alcohol boiling briskly during the extraction. The rate of extrac- 
 tion may be controlled by the use of an electric hot-point stove, 6 in. in 
 diameter, and using the full current of 2.2 amperes at 110 volts. The volume 
 of alcohol in the flask should be 125 cc. Protect the flask from drafts. Under 
 these conditions the tube should siphon over at least 33 times in 1 hour. The 
 condenser should be able to return all the alcohol volatilized during the vigor- 
 ous boiling of the contents of the flask, the object being to effect the maxilthum 
 extraction during the specified time. : 
 
 The weight of the residue insoluble in alcohol thus obtained divided by the 
 weight of the sample, and this quotient multiplied by 100 is the percentage of 
 alecohol-insoluble matter in the lac. 
 
 Nore.—When the determination of alcohol-insoluble matter in bleached 
 shellac is required, the sample shall be dried if in the form of bars or hanks 
 or ground shellac, as the water present dilutes the alcohol to a point where 
 solution may not be complete. It is recommended that in preparing shellac 
 for this determination, a separate portion be dried by exposure to the air in 
 a thin layer, without the application of heat. 
 
 FIGURE 192 
 
 Filtering Device. 
 (0) Gooch Filtration Method (Not Applicable for Stick, Seed or Grain 
 Lac and Bleached Shellac). 
 
 SOLUTIONS REQUIRED 
 4. 95-per-cent Alcohol.—Specially denatured alcohol, U. 8S. Internal Revenue 
 Bureau Formula No. 1 or Formula No. 30. 
 
 METHOD 
 5. Grind a 50-g. sample fine enough to pass a 40-mesh sieve. Weigh ac- 
 curately 2 g. of the sample and transfer to a small beaker, heat the shellac 
 with 25 ec. of 95-per-cent alcohol. Prepare a Gooch crucible with an asbestos 
 
 pad in the usual manner* and dry it to constant weight. Arrange the crucible 
 tor filtration by suction and pour sufficient boiling alcohol through it to thor- 
 
 oughly heat the crucible. 
 
 Note.—A cold crucible will congeal the wax and prevent filtration. 
 
 *For the preparation of the Gooch crucible see any standard text on 
 quantative analysis, for example, Fresenius (Cohn Translation), p. 120, 1904, 
 or Treadwell-Hall, third edition, Vol. II, p. 26. 
 
520 Shellac Analysis 
 
 Immediately filter the boiling solution through the crucible, using suction, 
 transfer the insoluble material from the beaker to the crucible, using a “police- 
 man” if necessary and a wash bottle containing hot alcohol until the washings 
 are colorless and then wash five more times, nearly filling the crucible each 
 time with boiling alcohol. 
 
 Norr.—It will be necessary to shut off the suction momentarily to fill the 
 crucible. 
 
 Wash off any film of shellac on the sides or bottom of the crucible with hot 
 alcohol and dry to constant weight in an oven at 105 to 110°C. The weight 
 of the residue in the crucible, multiplied by 100 and divided by the weight of 
 the sample, is the percentage of material insoluble in hot alcohol. 
 
 DETERMINATION OF ROSIN 
 
 SOLUTIONS REQUIRED 
 6. Acetic Acid.—99-per-cent glacial acetic acid having a melting point of 
 14.8° C., free from reducing impurities as shown by its action on a bichromate 
 in sulfuric acid. 
 
 NorE.—If these requirements are not met the results of the rosin determina- 
 tion will be erratic. 
 
 Iodine Monochloride Solution—Dissolve 13 g. of iodine in a liter of acetic 
 acid, using gentle heat if necessary, determining the strength by titration 
 with thiosulfate. Set aside 50 to 100 cc. of the solution and introduce dry 
 chlorine gas into the remainder until the characteristic color change occurs, 
 and the halogen content has been doubled. By titration, ascertain if the halo- 
 gen content has been more than doubled, and if so reduce it by adding the 
 requisite quantity of the iodine acetic acid solution. A slight excess of iodine 
 does no harm but an excess of chlorine must be avoided. 
 
 Chloroform.—Should be chemically pure. 
 
 Sodium Thiosulfate Solution.—Dissolve 24.83 g. of the pure salt in a liter 
 of cold, boiled, distilled water. Standardize by titrating against freshly re- 
 sublimed iodine. It is recommended that the resublimed iodine be collected 
 into a glass-stoppered weighing bottle and weighed after cooling. 
 
 Starch Solution.—Dissolve 0.2 g. of starch per 100 ec. of water and boil. 
 
 METHOD 
 
 7. Introduce 0.2 g. of ground shellac into a 250 ec. dry bottle of clear glass 
 with a ground-glass stopper, add 20 cc. of glacial acetic acid and warm the 
 mixture gently on top of a hot water bath until solution is complete (except 
 for the wax). A pure shellac is rather difficultly soluble; solution is quicker 
 according to the proportion of rosin present. Add 10 ec. of chloroform and 
 cool the solution to 21.5 to 22.5° C. The bottles should be allowed to stand half 
 immersed in a shallow pan of water, well insulated or equipped with a suitable 
 thermostat, at least 30 minutes at 21.5 or 22.5° C. before the Wijs solution is 
 added. Add 20 ce. of Wijs solution (which shall be at a temperature of 21.5 
 to 22.5° C.) from a pipette, having a rather small delivery aperture (about 
 30 seconds). Close the bottle, place it back into the pan of water, and note 
 the time. The bottles must be kept half immersed in water at 21.5 to 22.5° C. 
 
 aD 
 
 Oe 
 
Shellac Analysis 521 
 sn Snel ere 
 
 during the one hour that the shellac is exposed to the Wijs solution. Agitate 
 the bottles occasionally during that hour. 
 
 Norr.—If a number of samples are being run, at least 5 minutes should be 
 allowed between the additions of the Wijs solution. 
 
 After exactly one hour, add 10 ee. of freshly prepared 10-per-cent potassium 
 iodide water solution, washing into the bottle any Wijs solution on ‘the stopper 
 with the same. Titrate the solution immediately with the 0.1 N sodium thio- 
 sulfate solution, allowing the solution to run in slowly (about 25 to 30 ce.) 
 with vigorous shaking until the solution becomes a straw color. Now add 15 
 ec. of freshly prepared starch solution and finish titrating. The end point is 
 sharp, as the reaction products of shellac remain dissolved in the chloroform ; 
 any color returning after 4 minute or so is disregarded. 
 
 A blank determination shall be run at the same time on the reagents. The 
 blank is necessary on account of the well-known effect of temperature changes 
 on the yolume, and possibly loss of strength of the Wijs solution. A sample 
 of pure shellac of known iodine value should also be run with every set of 
 tests on unknown samples. 
 
 In the case of grossly adulterated samples, or in the testing of pure rosin, 
 it is necessary to use, instead of 0.2 g. of material, a smaller amount (0.15 g. 
 or 0.1 g.) in order that the excess of iodine monochloride may not be too 
 greatly reduced, since the excess of halogen is one of the factors in determining 
 the amount of absorption. In case less than 25 cc. of the thiosulfate solution 
 are required, another test should be made, using a smaller amount of the 
 shellac to be tested. 
 
 In weighing shellac, some difficulty is at times experienced on account of 
 its electrical properties. In very dry weather it may be found that the neces- 
 Sary handling to prepare it for weighing has electrified it, and that it may be 
 necessary to leave it on the balance pan at rest for a few minutes before taking 
 the final weight. 
 
 No pure shellacs show a higher iodine absorption than 18. As pure shellae 
 is relatively a high-priced material and as the variation between its highest 
 and lowest figures is not great, it is recommended that 18 should be taken as 
 the standard figure for rosin-free Shellac, determined by the method above 
 described. 
 
 The determination for added rosin in bone-dry bleached shellae is run 
 the same as above, except that the iodine absorption of pure bleached shellac 
 is taken as 10 instead of 18. 
 
 It is recommended that the value for the iodine number of rosin be taken 
 as 228. The results of using in this method the value of 18 as the iodine 
 number of shellac and 228 as the number of rosin, may be that a slightly lower 
 percentage of rosin, under some circumstances, will be found than that which 
 is actually present. 
 
 The percentage of rosin shall be determined from the formula: 
 
 fedine number of bleached shellac............00eecc.0. ecen det 18 
 a se eh OCLE tee Ian rae 2 oe Vege ohn new oe oe ene RN 228 
 os “ Si PEAS stat Rg ep ee oe Oe A SORE it 0 cee CRN NUE Ba Oe Lr 
 
 (2-18) 
 
 ———__- X 100 = percentage of rosin. 
 (228 — 18) " % 
 
522 Shellac Analysis 
 Todine number of bleached shellac....3.....U....una eure 10 
 oe of “ . POSIN sce eule vee sie 0 widp ble Wo enals alent onan 228 
 = a nD 6 4) ©: 4 F100 > ae IP REE CP v 
 (x —10) 
 —__-__-.- “~ 100== percentage of toe 
 (398-10) : § 
 
 DETERMINATION OF MOISTURE IN SHELLAC 
 
 SAMPLING 
 
 8. Both orange and bleached shellac give off volatile matter at tempera- 
 tures approaching 100° C. Bleached shellac alters chemically at these tempera- 
 tures, becoming less soluble in alcohol. For these reasons the usual method of 
 determining water by heating in the air bath at 100 to 110° C. is not applicable 
 in.the analysis of shellac. 
 
 9. Dry Bleached Shellac.—In sampling dry bleached shellac, about 1 1b. 
 should be taken from different parts of the barrel and finely ground by run- 
 ning through a coffee mill. No attempt shall be made to sieve it. It should 
 be rapidly mixed and transferred to a mason jar provided with a screw cap 
 and rubber ring seal. The jar should be filled not more than two-thirds full, 
 leaving room for a thorough mixing by shaking the contents. It should be 
 kept in a cool place and tested as promptly as possible. If too warm, the 
 shellac may tend to lump together, in which case the lumps must be broken 
 up by shaking the bottle. 
 
 10. Bars or Hanks.—In sampling bars or hanks it is recommended that a 
 whole hank be taken. It should be crushed and ground as rapidly as possible. 
 
 11. Ground Bleached Shellac.—Ground bleached shellac may be treated as 
 above, bearing in mind that the large amount of moisture present makes rapid 
 handling imperative. 
 
 METHOD 
 
 12. Dry-Bleached Shellac_—Weigh 5 g. of the finely ground sample in a 
 flat-bottomed dish about 4 in. in diameter and place the dish in a well-venti- 
 lated air bath for three to six hours at 38 to 43° C. One or two electric light 
 bulbs provide a convenient source of heat. The temperature should not be 
 allowed to rise above 48° C. 
 
 NoreE.—With poorly ventilated ovens the drying may take much longer. 
 Completeness of drying should be ascertained by continuing the treatment to 
 constant weight. Se 
 
 13. Hanks and Ground Bleached.—Proceed as in Section 12, but with the 
 exception that the dish and its contents be allowed to dry in the air, or in 
 a sulfuric acid desiccator over night before it is placed in the air bath. 
 
 14. Orange Shellac.—Proceed as in the case of Section 12. 
 
 Norr.—Dry-bleached shellac is also termed “bone dry,” “kiln dry,” “vac 
 dry,” “bleached shellac.” 
 
 NOTES 
 Average commercial orange shellac contains not over 2 per cent of moisture. 
 Average commercial regular dry-bleached and dry-refined bleached shellac 
 contain not more than 5 per cent of moisture. 
 Average commercial regular and refined bleached shellac as ground, hanks 
 or bars contain not more than 25 per cent of moisture. 
 
 o —— 
 
 7 wa 
 
Shellac Analysis bes 
 
 A. 8. T. M. TENTATIVE METHOD OF TEST FOR 
 DETERMINATION OF WAX IN SHELLAC 
 
 (“Machine Made” and Dry-Refined Bleached Shellac) 
 
 1. Dissolve 10 g. of shellac with 2.5 g. of carbonate of soda and 150 ce. of 
 hot water. Make the solution in a 200-cc. tall form beaker; immerse the 
 beaker in a steam or boiling-water bath and stir till the shellac is in solution. 
 Then cover with a watch glass, allow to remain in the water bath for 2 or 3 
 hours more without agitation, remove beaker from the bath and stand in cold 
 water. The wax will form a layer at the top. Filter the solution through 
 a 12-cm. folded filter paper, or a Buchner funnel (24 in. in inside diameter) 
 may be used. Cover the bottom of the funnel with a disk of filter paper, mix 
 1 g. of filter cell with water and pour on the filter. Add 0.5 g. of filter cell 
 to the solution, and filter with the aid of a vacuum. After washing out the 
 soluble shellac pour on a few cubic centimeters of alcohol to facilitate drying. 
 When dry, remove the filter bed and wrap in filter paper, and extract in 
 suitable continuous extraction apparatus with chloroform or carbon tetra- 
 chloride for 13 to 2 hours. Dry the wax at 105° C. to constant weight. 
 
 Nore.—The filter cell used should be extracted with either of the solvents, 
 chloroform or carbon tetrachloride. : 
 
 2. In the case of dry-bleached refined shellac, dissolve 50 g. in 250 cc. of 
 alcohol, add 1 g. of oxalic acid and stir till all is dissolved. Then add 0.5 g. of 
 filter cell and allow to settle over night. Run the clear liquor through a Gooch 
 crucible prepared with asbestos. Wash the sediment of wax and filter cell on 
 the crucible with alcohol. Dry at a low temperature, remove the asbestos 
 mat, wrap in filter paper and extract in continuous extraction apparatus with 
 chloroform or carbon tetrachloride. Dry the wax at 105°C. to constant 
 weight. 
 
 Note.—The carbon tetrachloride and chloroform should be redistilled before 
 using, as they must not leave a non-volatile residue. 
 
 A. 8. T. M. TENTATIVE METHODS OF 
 TESTING SHELLAC VARNISH 
 
 Shellac varnishes are made by dissolving shellac in alcohol and are desig- 
 nated in the trade in terms of pounds of shellac per gallon of alcohol, the 4.4.5 
 and 5-lb. cut goods being most commonly used. Specially denatured alcohol 
 (Formula No. 1) is largely used, and occasionally wood alcohol and butyl 
 alcohol are used. Pure grain alcohol, or Formula No. 35 denatured, is used for 
 confectioner’s varnish or glaze. 
 
 I. GENERAL 
 
 1. (a) All tests, unless otherwise stated, shall be made at room temperature 
 between 21 and 32° C. (70 and 90° F.)). 
 
 (b) The sample of shellac varnish shall be thoroughly agitated in the con- - 
 tainer immediately before portions are removed for the various tests and the 
 unused portion shall be kept in a tightly stoppered glass container, in a dark 
 place. 
 
524 Shellac Analysis 
 
 II. DETERMINATION OF COLOR 
 2. The color of the well-shaken sample shall be compared with the color of 
 the well-shaken sample of shellac varnish mutually agreed upon for color by 
 the buyer and seller. The color comparison shall be made in clear glass tubes 
 of the same diameter. 
 
 Ill. DETERMINATION OF NON-VOLATILE MATTER 
 Method (a). 
 
 APPARATUS 
 
 3. The apparatus shall consist of the following: 
 
 (a) A weighing bottle for volatile liquids or a Grethan pipette. 
 
 (b) A tin-foil dish, approximately 1} in. in height and 23 in. in diameter. 
 
 (c) Prepared Sand, prepared as follows: Sieve sea-sand to remove any 
 foreign material. Digest with hot HCl for about one hour. Wash with water 
 to remove all the acid and soluble impurities. Ignite and put in a desiccator to 
 cool. Preserve in a tightly stoppered bottle. 
 
 PROCEDURE 
 
 4. Put 10 g. of the prepared sand and a short glass rod in the tin-foil dish. 
 Record the exact weight of the dish and contents. Transfer about 1 g. of 
 the sample from the weighing bottle to the dish. Record the exact weight of 
 the sample taken which will be the difference in weight of the weighing bottle 
 before and after the removal of the sample. Thoroughly mix the varnish and 
 sand with the glass rod and place the dish in an oven maintained at 105° C. for 
 one hour. Remove the dish from the oven, allow it to cool and weigh. The 
 increase in weight of the tin-foil dish containing the sand and glass rod is the 
 weight of the non-volatile matter in the sample of varnish taken. 
 
 Method (b). 
 
 5. Follow the procedure given in the Standard Methods of Testing Oleo- 
 Resinous Varnishes (Serial Designation: D 154) of the American Society 
 for Testing Materials,* for non-volatile matter in oleo-resinous varnish, with 
 the exception that the weight of sample taken shall not exceed 1.5 g. With 
 varnishes made by “cutting” over 5 lbs. of shellac per gallon of alcohol, add 10 
 g. of sea sand, prepared as described in Section 3 (c), to the container and 
 mix with the sample by means of a short glass rod (previously weighed with 
 the container and sand). 
 
 6. (a) Since bone dry white shellac may lose up to 5 per cent of its weight 
 when heated at 105° C., the weight of non-volatile matter found in the case of 
 white shellac varnish should be divided by the factor 0.95. 
 
 (b) On account of the efforts of the orange varnish manufacturers to 
 produce cleaner varnish for the trade by the use of centrifuge machines and 
 improved filtration apparatus, the same allowance of 5 per cent, which is made 
 in calculating white shellac varnish body, shall be used in determining clari- 
 fied orange varnish body. This 5-per-cent allowance is based on the fact that 
 2 per cent of moisture has always been allowed in the calculation, and in 
 addition the 3 per cent of insoluble matter customarily encountered in varnish 
 grades of orange shellac is eliminated by the modern methods of varnish 
 production. 
 
 *1924 Book of A.S.T.M. Standards. 
 
 Te ee 
 
Shellac Analysis 525 
 
 The calculations of the body of white and orange shellac varnishes are 
 made according to the methods shown in the following examples: 
 
 Example. 
 White Shellac Varnish and Clarified Orange Shellac Varnish: 
 Suerte Ore varnish CAken. 6.50.06. ee eee ee wees 1.2973 g. 
 iveimno or residue (after drying)............3..6 Oieao f. 
 
 0.5235 
 0.95 X 1.2973 
 This percentage corresponds to 5 lb. per gallon. 
 
 The above orange-varnish calculation refers to ready-cut varnish as 
 obtained in the regular paint and varnish shops. 
 
 Per cent of body = X 100 = 42.45 per cent. 
 
 The better grades of orange shellac, which contain little insoluble matter, 
 can and are cut in alcohol and simply strained through an S0Q-mesh screen. 
 Such a varnish would contain practically all the finely divided inert matter 
 and the calculation of the body of such a varnish would be made as follows: 
 
 Since dry orange shellac may lose up to 2 per cent of its weight when 
 heated at 105° C., the weight of non-volatile matter found in the case of orange 
 shellac varnish should be divided by the factor 0.98. 
 
 The calculation of the body is made according to the method shown in the 
 following example: 
 
 Example. 
 Unclarified Orange Shellac Varnish: 
 Berar eGr VATHISH TAKEO ck. oa ce cnc oe ececceee 1.3200 g. 
 MW ermut 0: residue (after. drying)........0.5...e00. 0.5491 g. 
 
 0.5491 
 0.98 X 1.3200 
 
 This percentage corresponds to 5 lb. per gallon. 
 
 Per cent of body = xX 100 = 42.45 per cent. 
 
 (ec) To convert the percentage of solids (residue) of the varnish into 
 pounds per gallon, from the percentage of solids expressed in pounds of solids 
 in 100 lb. of varnish, the pounds of solvent is found by difference. The weight 
 of solvent divided by 6.7793 (the weight of one gallon of denatured alcohol 
 (Formula No. 1) at 15.5° C. (60° F.), gives the number of gallons of alcohol 
 present. From this the number of pounds of shellac per gallon of alcohol is 
 determined. 
 
 Example. 
 100 — 30.68 (solids found) = 69.32 lb. of alcohol. 
 69.32 
 6.7793 
 30.68 
 10.23 
 
 For convenience, tables are appended hereto giving pounds of shellac per 
 gallon for varnishes for various specific gravities. See page — 
 IV. DETERMINATION OF MATTER INSOLUBLE IN HOT ALCOHOL 
 7. (@) Matter insoluble in hot alcohol shall be determined by the continuous ~ 
 extraction method or by the Gooch filtration method as given in the Standard 
 Methods of Testing Shellac (Serial Designation: D 29) of the American 
 Society for Testing Materials.* 
 
 = 10.23 gallons of alcohol. 
 
 = 3 lb. per gallon. 
 
 *1924 Book of A.S.T.M. Standards. 
 
526 Shellac Analysis 
 
 (b) In the ease of the continuous-extraction method, weigh an amount of 
 shellac varnish corresponding, as closely as practicable, to 5 g. of non-volatile 
 matter, while with the Gooch filtration method take a weight of sample cor- 
 responding closely to 2 g. of non-volatile matter. 
 
 V. DETERMINATION OF WAX 
 8. In the determination of wax, dilute an amount of the varnish that will 
 contain approximately 10 g. of dry shellac with 95-per-cent specially-denatured 
 aleohol to about 200 ce. and proceed as in the Standard Method of Test for 
 Determination of Wax in Shellac (Serial Designation: D 29) of the American 
 Society for Testing Materials* 
 
 VI. DETERMINATION OF PURITY 
 A. Qualitative Tests 
 9, (a) Copal.—Filter some of the varnish through dry paper into a large 
 test tube 6 by 3 in.). To 10 ce. of the filtrate add 99-per-cent methyl alcohol 
 to nearly fill the tube and thoroughly mix. The formation of a precipitate 
 after standing is an indication of copal. Shellac free from copal should remain 
 clear under the conditions given above, , : 
 (b) Rosin.—Add 20 ec. of absolute alcohol or glacial acetic acid (melting 
 point 13 to 14°C.) to 5 ee. of the varnish and thoroughly mix. Add 100 cc. 
 of petroleum ether and again thoroughly mix. Add approximately 2 liters of 
 water and separate a portion of the ether layer (at least 50 ec.) and filter if 
 cloudy. Evaporate the petroleum ether and test the residue by the Halphen- 
 Hicks reagent as follows: 
 
 Solution A.—One part by volume of phenol dissolved in 2 parts of carbon 
 tetrachloride. 
 
 Solution B.—One part by volume of bromine dissolved in 4 parts of carbon 
 tetrachloride. 
 
 Add 1 to 2 cc. of solution A to the residue left after evaporation of the petrole- 
 um ether solution. Pour this solution into a cavity of an ordinary porcelain 
 color reaction plate and fill an adjacent cavity with solution B. Cover the 
 plate with a watch glass and note the color, if any, produced by the action of 
 bromine vapors on solution A. A decided purple or blue color is an indication 
 of rosin. 
 
 B. Determination of Iodine Number 
 
 Method (a). 
 
 10. (a) With the percentage of solids known, weigh accurately in a suit- 
 able pipette, or weighing bottle for volatile liquids, an amount of varnish cor- 
 responding to 0.20 g. of dry shellac and transfer to a 250-cce. glass-stoppered © 
 bottle. In case heavy adulteration is suspected, weigh an amount of varnish 
 corresponding to 0.15 g. of shellac or less if necessary. 
 
 (b) Warm the bottle in a water bath at a temperature of 75 to 80° C, for 
 about 15 minutes, aspirating the alcohol vapor until the residue is practically 
 dry. Cool and add 20 ce. of acetic acid (melting point, 14.8° C.). Proceed in 
 accordance with fhe method for iodine number described in the determination 
 of rosin in the Standard Methods of Testing Shellac (Serial Designation: D 
 29) of the American Society for Testing Materials.* 
 
 *A.S.T.M. Standards Adopted in 1925. 
 
Shellac Analysis 527 
 eee 
 
 ALTERNATE PROCEDURE 
 Method (Db). 
 
 11. Transfer about 1.5 cc. of the varnish by means of a pipette to a flat- 
 bottomed glass or porcelain dish at least 8 em. in diameter. Add 1 fo 2 COLOL 
 95-per-cent alcohol to spread the varnish evenly over the bottom of the dish. 
 Heat the dish and contents at 75 to 80° C. for one-half hour. Scrape the resi- 
 due from the dish, accurately weigh 0. 20 g.., and transfer to a 250-ce. glass- 
 stoppered bottle. In case of badly adulterated samples, a proportionately 
 smaller weight of sample should be taken. Proceed in accordance with the 
 method for iodine number described in the determination of rosin in the 
 Standard Methods of Testing Shellac (Serial Designation: D 29) of the 
 American Society for Testing Material.* 
 
 12. (a) If a qualitative test shows the presence of copal but no rosin, the 
 amount may be estimated from iodine number, taking the iodine number of 
 copal as 180 and making the calculation in an analogous manner to that for 
 rosin described in Section 7 of the Standard Methods D 29. 
 
 (b) If a qualitative test shows the presence of rosin but no copal, the 
 calculation of the percentage of rosin may be made as described in Section 
 7 of the Standard Methods D 29. 
 
 APPENDIX 
 
 Information concerning the volatile portion of a shellac varnish May be 
 obtained by distilling approximately 50 ce. of varnish to dryness (avoiding 
 decomposition of the shellac through excessive heat at the end) and determin- 
 ing the boiling range of this distillate by a redistillation. A portion of the 
 final distillate may be diluted with water to ascertain if other solvents, such 
 as naphtha or benzol, have been added. These will] separate on dilution and 
 the layer formed may be measured. 
 
 RELATION OF POUNDS Or SHELLAC PER GALLON TO SPECIFIC GRAVITY 
 
 — —S— 
 
 Wire SHELLAC VARNISH: Dry BLEACHED SHELLAC (5 PER CENT MOISTURE), 
 DENATURED ALCOHOL, FoRMULA No, 1, 95-PER-CENT, 
 
 SHELLAC, SPECIFIC WEIGHT 
 
 LB. PER GAL. GRAVITY DEG. PER 1 GAL. 
 OF ALCOHOL 15.5° C. (60° F.) Baumnp VARNISH, LB, . 
 Taking Weight of Water 1 gal.—8.33 Ib. 
 ne 0.9056 24.60 7.544 
 A 0.9167 22.70 7.636 
 _ Er 0.9278 20.90 7.729 
 SS ee 0.9375 19.33 7.809 
 a 0.9464 "17.92 7.884 
 a 0.9530 16.90 7.938 
 sek s< 2 Ae 0.9597 15.90 7.994 
 
 *1924 Book of A.S.T.M. Standards. 
 
528 Shellac Analysis 
 
 ORANGE SHELLAC VARNISH: TN SHELLAC 2 PER CENT MoIstuRE), DENATURED 
 ALCOHOL, FoRMULA No. 1, 95-PER-CENT, 
 Taking Weight of Water 1 gal.—8.83 Ib. 
 
 Re Gatebase rigs aiaer ey 0.900 25.55 7.497 
 1 eee reer n Se otk 0.9114 23.6 7.592 
 es A a eee See 0.9228 oy 7.687 
 OY, Gal apres Wes Mar ent 0.9318 20.25 7.762 ; 
 Bee of Seo 5 ee oe 0.9895 19.0 - 3 7.926 | 
 Bo kate eee ee 0.9500 17.36 7.914 
 Bilas cs ety eee 0.9554 16.53 7.958 
 
 Note 1.—Shellac varnishes will not always agree exactly with the specific 
 gravity given above, estimated at 15.5° C. (60° F.). They will vary somewhat, 
 due to more or less moisture and insoluble matter contained in the white and 
 orange shellacs and also to loss of solvent by evaporation. However, the 
 figures given agree closely with theoretical and practical results. 
 
 Nore 2.—If 10 lb. of shellac is cut in 1 gal. of alcohol the yield is 2 gal. of 
 varnish, hence 10 lb. of shellac cut in alcohol is equivalent to 1 gal. 
 
 Example. ; 
 4 lb. shellac cut in 1 gal. alcohol yields 1.4 gal. varnish 
 44 lb. shellac cut in 1 gal. alcohol yields 1.45 gal. varnish 
 5 Ib. shellac cut in 1 gal. alcohol yields 1.50 gal. varnish 
 
 The following table shows corresponding percentages of gum and alcohol in 
 shellac varnishes of the following pounds of gum cut per gallon, No. 1 Specially 
 Denatured Alcohol 95-per-cent, by volume at 15.5° C. (60° F.). 
 
 POUNDS OF 
 GUM PER 
 GALLON OF ; GUM, ALCOHOL, 
 ALCOHOL PER CENT PER CENT 
 BO eis oc dele \ave'e sla eie)o 5 Oa tace tye ae ee ee oe 30.68 69.32 
 BiDe. oo vlaie «ale ib dpi acnce Bie: Ghee ale eters ce vies betel iat eee 32.41 67.59 
 BO ss hada bn aw tte c ele Otic eaeee Se eens oe ee 34.05 65.95 
 ay 65 EY Aen She N ere ee A oe 35.61 64.39 
 AAV, os Saw sy ©. scale & © Gael suave RI ReLn inion el Ps alta ae 37.11 62.89 
 A ow ievece im anaemia Utah "ecole Malle Scheie Up se ek 38.54 61.45 
 he FOE aed -d win. wha wiwea. o mile eine Costin te nie eens ete 39.90 60.10 4 
 ATE b vcalGn 2 dc a Rew ee bcis ake SiGe io ea ea 41.20 58.80 ; 
 5.0 oc Sie Oe Ss bbe ee Mes She pe eal ae 42.45 57.55 
 Ty 45 a ere a ND eI aK ER 43.65 56.35 
 BBs sucks ale bw Gio oF miele 6a oum gonie othe Gate tame raceatn ean 44.79 55.21 
 Wy {i Pee ee a ere ee Pe ee ee ee ae 45.89 54.11 
 GOs oo Sv 9 bis 6 we el bac ete aoe e 46.98 53.02 
 
 The weight of 1 gal. of alcohol (No. 1 Special) at 15.5° C. (60° F.) is 6.7793 
 lb. according to Regulations No. 61, U. S. Internal Revenue. 
 
 The table given above is taken from the Official Booklet of the United 
 States Shellac Importers’ Association. 
 
 Note 3.—Method (a) covering Determination of Non-Volatile Matter in 
 Varnish is the official method of the United States Shellac Importers’ 
 Association. 
 
 Nore +.—The above figures are the most important in the tables to the 
 varnish industry as considerable shellac varnish is now sold by weight, or the 
 gallonage is determined by dividing the net weight by its corresponding factor. 
 
 Nore 5.—Hydrometers should not be employed to determine the specific 
 
 ese ee 
 
 gravity or degree Baumé of a shellac varnish, as readings so obtained are 
 unreliable and inaccurate. The specific gravity of a shellac varnish can be ¥ 
 accurately determined either with a specific gravity bottle (pyknometer) or j 
 
 by weighing accurately 100 cc. of the varnish at 60° F. in a 100-ce. graduated 
 flask, which has been calibrated with distilled water at the same temperature. 
 
Shellac Analysis 529 
 
 Direct Method for Rosin in Shellac.—A direct method for 
 determining the amount of rosin in shellac has long been de- 
 sired. Such a method is being worked out by the Bureau of 
 Standards and promises to be very satisfactory. It is based 
 upon the solubility of rosin in certain hght fractions of petro- 
 leum hydrocarbons. See the Bureau of Standards Techno- 
 logic Paper No. 232. This petroleum ether method has not 
 superseded the Wijs iodine method where a numerical value 
 for percentage of rosin is desired. It is, however, of great 
 value in determining the adulteration of shellac varnishes. 
 
 Steele Modification of the McIlhiney Method for the Detec- 
 tion and Estimation of Adulterants in Shellac Varnish.—Pe- 
 troleum ether distilling between 55 and 75° C.* was obtained 
 by the distillation on the steam bath of either commercial pe- 
 troleum ether or aviation gasoline, fighting grade.+ Glacial 
 acetic acid was diluted with water until its solidification point 
 was between 13 and 14° C. 
 
 Method.—In case of a shellac varnish, determine the per- 
 centage of nonvolatile matter. Place a portion of the well 
 mixed sample in a stoppered container. Weigh the container 
 and sample. Transfer a weight of the sample corresponding 
 as closely as practicable to 2 g. of nonvolatile matter to a 2- 
 hter Florence flask, the neck of which has a volume of over 
 100 ce. and restopper the container. Weigh the container 
 again and by difference calculate the exact weight of the por- 
 tion transferred to the flask. Calculate the exact weight of 
 shellac in the sample taken from the percentage of nonvolatile 
 matter in the varnish. The procedure from this point is the 
 same for dry and cut shellac. Add 20 ce. of the special acetic 
 acid and heat the flask until the shellac resin and wax are dis- 
 solved. With certain shellac adulterants there may be a small 
 amount of resin which cannot be dissolved. Cool the flask to 
 room temperature (19-21° C.) hereupon a part of the natural 
 shellac wax usually separates. Add slowly from ‘a pipette 50 
 ec. of the petroleum ether cooled to 19-21° C., with constant 
 shaking of the flask, allowing one to two minutes for the addi- 
 tion. Add all at once from a graduated flask 100 ec. more of 
 the petroleum ether kept at 19-21° C., stopper the flask and 
 
 * A fraction with initial boiling point of 40° C. should be satisfactory, 
 provided it is not used in extremely hot weather . 
 + Bureau of Mines Technical Paper No. 323, p. 1. 
 
530 Shellac Analysis 
 
 a 
 shake vigorously. While shaking the flask, slowly add tap 
 water kept at 19-21° C., until the shellac has separated as an 
 amorphous mass. Half fill the flask with water and agitate 
 so as to thoroughly wash the ether layer. Add water until 
 the petroleum ether layer nearly fills the neck of the flask, cork - 
 and let the flask stand until the ether layer is free from sus- 
 pended particles. Transfer 100 ce. of the ether layer to a 100 
 ec. graduated flask. It is convenient to fit the large flask with 
 a two-hole stopper with tubes arranged like a wash bottle, so 
 that the ether solution can be blown into the graduated flask. 
 
 Evaporate the 100 cc. of petroleum ether solution, portion 
 wise if necessary, in a small weighed Erlenmeyer flask on a hot 
 plate. When the dry point is reached, suck out the residual 
 solvent vapors, cool the flask, and weigh. The weight of the 
 residue multiplied by 150 and divided by the weight of shellae 
 taken is the percentage of ‘‘matter soluble in petroleum 
 ether.’’ Dissolve this residue in 25 ee. of a mixture of equal 
 volumes of 95 per cent denatured alcohol and benzol (the mix- 
 ture should be previously titrated to a faint pink color with 
 dilute alkali, using phenolphthalein as an indicator) and ti- 
 trate in the cold with 0.1 N alcoholic sodium hydroxide with 
 phenolphthalein as an indicator. Calculate the acid number 
 of the ‘‘matter soluble in petroleum ether’’ (milligrams of 
 KOH required for 1 g. of petroleum ether residue). Transfer 
 
 Suggested Method for Rating Samples of Shellac 
 
 Petroleum Acid number of 
 ether soluble Ros:n test residue Purity 
 percentage 5 
 7.0 OF esas, a2} INCZATIVON Se) ernie 60-90 Ris a. eens Pure. 
 7,058.0. F008 2 Positivec. aan Se ae May be greater or | Slightly adulterated; probably 1-2 per cent 
 less than 90. rosin, as in ‘‘Superfine”’ 
 70-8032 nen Werativ Gh, sc eratacee ae 0 oy Aine ee. sors Suspicious; no adulteration proved. 
 8.0-12.0...... POsitivednncok tenes Generally, but not | Somewhat adulterated; probably a “T.N.” 
 always over 90. shellac. 
 80292. 05 au Negative: ci normconlonncs Oe hats nate Somewhat adulterated with an adulterant 
 other than rosin. 
 12.0-20.0.....) Positive or nega- }|..... GO. = ccm Badly adulterated; possibly as high as 40 
 tive. per cent adulteration. 
 ver QO. Oke cals ores AO pirate ascent iiaecs re bo Weegee Paes Ac Grossly adulterated; possibly no shellac 
 present. 
 
 most of the petroleum ether layer remaining in the Florence 
 flask to a small beaker or flask and evaporate to dryness. | 
 Test this residue for rosin by means of the Halphen-Hicks test 
 already referred to. Report a faint purple or blue coloration 
 
Shellac Analysis 531 
 
 as ‘‘faint test for rosin’’ and a deep purple or blue as ‘‘de- 
 eided test for rosin.”’ 
 
 An examination of the results on many samples tested by 
 this method indicate that a large number of the samples of 
 shellac were free from rosin, as shown by a qualitative test 
 and by an iodine value below the arbitrary accepted limit of 
 18. Such samples can probably be safely considered as un-— 
 adulterated shellacs. These samples of pure shellac, with 
 few exceptions, yielded values between the limits of 6.0 and 
 7.0 per cent for material soluble in petroleum ether and acid 
 values for this residue between the limits of 60 and 90. 
 
 Testing the Effect of Metals and Solvents upon the Darken- 
 ing of Shellac Solutions.—Producers of shellac varnishes have 
 occasionally noted darkening of their products which have 
 stood for a considerable period of time upon dealers’ shelves 
 or in store rooms. It was thought that the type of alcohol 
 used in cutting the shellac may have had some influence upon 
 this phenomenon, or that metals taken into solution during 
 the cutting process may have been responsible. While as a 
 rule wooden barrels are used for agitating shellac, metal bar- 
 rels have sometimes been employed, or the fittings in the cut- 
 ting apparatus may have contained iron parts. Iron spigots 
 may have been employed, or the shellac solution may 
 have come in contact with other metals previous to filling 
 into small containers. Containers used for shellac may be 
 ordinary tin cans or, as in many instances as at present, glass 
 bottles fitted with metal covers which are insulated from con- 
 tact with shellac by paper gaskets. 
 
 In order to get some information as to the cause of this 
 darkening phenomenon, a series of tests have just been made 
 upon four grades of shellac. These consisted of Clean Dry 
 Bleached Shellac, Superfine Shellac, Fine Orange Shellac, and 
 TN Shellac, the latter being one of the lower qualities import- 
 ed into this country. All grades of shellac contain organic 
 acids, and therefore may be susceptible to reaction in contact 
 with various metals. The five grades of alcohol experimented 
 with were as follows: | 
 
 COMPLETELY DENATURED ALCOHOL FORMULA No, 1 
 
 100 parts by volume of Ethyl Alcohol] (not less than 160 proof) 
 10. ~=—s parts by volume of Approved Wood Alcohol 
 0.5 part by volume of Approved Benzine (Kerosene) 
 
532 Shellac Analysis 
 
 SPECIALLY DENATURED ALCOHOL FORMULA No. 2 
 
 100 parts by volume Ethyl Alcohol (not less than 160 proof) 
 +) parts by volume Approved Wood Alcohol 
 
 SPECIALLY DENATURED ALCOHOL FORMULA No. 2-B 
 
 100 parts by volume Ethyl] Alcohol (not less than 160 proof) 
 0.5 part by volume Specified Benzol 
 (The above formula is allowed in a closed and continuous process only.) 
 
 SPECIALLY DENATURED ALCOHOL FORMULA No, 3-A 
 
 100 parts by volume Ethyl Alcohol (not less than 160 proof). 
 u parts by volume Commercially Pure Methyl Alcohol having a specific 
 gravity of not more than 0.810 at 60° F 
 
 = { 
 COMPLETELY DENATURED ALCOHOL FORMULA No. 5 
 
 100 parts by volume Ethyl Alcohol (not less than 160 proof) 
 2 parts by volume Approved Wood Alcohol 
 0.25 part by volume Approved Pyridin Bases 
 0.50 part by volume Approved Benzine (Kerosene) 
 
 General information regarding the specifications used in 
 purchasing the various denaturants referred to in the above 
 formulas is contained in Appendix to Regulations No. 61, a 
 pamphlet issued by the Treasury Department, entitled ** For- 
 mulae for Completely and Specially Denatured Alcohols.”’ 
 This may be obtained from the Government Printing Office, 
 Washington, D. C., for five cents per copy. 
 
 The various anata referred to above were cut in the alco- 
 hols in the proportion of 3 lbs. of shellac per gal. of alcohol. 
 The cutting was done in glass. This produced twenty differ- 
 ent samples. Each of these was divided into four parts and 
 placed in four glass jars with paper-insulated caps. In one of 
 these jars for each group there was placed a few bright iron 
 carpet tacks. In another jar a few small strips of sheet tin 
 were placed. In the third jar a few small pieces of mossy 
 granulated zine were placed. The remaining jar of shellac 
 was used as a blank, no metal being added to it. These four 
 sets of tests (a total of eighty jars) were then shaken every 
 day for a period of 5 minutes until a test period of six weeks 
 had elapsed. During this time frequent inspections were 
 made. It was noted that the shellacs containing the iron, tin, 
 or zine gradually darkened in color, while those that did not 
 contain metal were only slightly affected by light. It was 
 also noted that the clear liquid in each sample, above the set- 
 tled wax, wherever metals were placed in the solutions, was 
 very much darker than those without metals. This was espe- 
 cially true of the orange shellac. 
 
Shellac Analysis 533 
 
 It was also noted that the grade of alcohol used seemed to 
 affect the color to some extent. The samples remaining the 
 lightest in color were almost invariably those produced with 
 Specially Denatured Formula No. 1 or Completely Denatured 
 Formula No. 1. Specially Denatured. Formula No. 3-A was 
 next in order. This was followed by Specially Denatured 
 Formula No. 2-B. The darkest of all in practically every in- 
 stance were those made with Completely Denatured Formula 
 No. 5 which contained pyridin. It is probable that the pyri- 
 dine base may have exerted some action upon the shellac, 
 which would cause the darkening phenomenon. This, how- 
 ever, was not nearly as pronounced as the effect of the metals. 
 
 A comparison of the colors of the shellacs at the conclusion 
 of the tests showed that the sheets of (tin-coated iron) tin 
 caused the color to change to a very deep greenish brown. 
 Next in order came the iron which had a somewhat similar 
 effect but not as pronounced as the tin. The zine caused a 
 change to a rather pleasing shade of brownish red, slightly 
 darker than the original sample but not as dark as the colors 
 produced by the tin and the iron. In this connection, it is 
 interesting to note that the type of tin plate usually produced 
 today probably contains very much less tin than several 
 years ago. ‘This is due to the present shortage of tin. Thus, 
 for instance, tin cans may contain a coating of tin which does 
 not thoroughly coat the iron. Pin holes are present and the 
 exposed base metal is therefore subject to fairly rapid cor- 
 rosion when in contact with corrosive liquids. It is therefore 
 possible that the results shown in these tests with the sheets 
 of tin plate were due more to the effect of the iron than to the 
 tin, the sheared specimens leaving reactive surfaces of un- 
 coated iron. 
 
 Another interesting phenomenon noted was the viscosity 
 of the various samples after standing. For instance, in every 
 case the shellacs treated with metals were considerably higher 
 in viscosity than the original samples in which metal was not 
 placed. Asarule, the difference in viscosity ranged from one- 
 half to one bubble on the Gardner-Holdt viscometer. The 
 shellacs were rated for viscosity in the following order: 
 
 Original Shellac : Iron contaminated shellac 
 Zine contaminated shellac Tin contaminated shellac 
 
534 Shellac Analysis 
 
 The latter was very much greater in viscosity than the 
 others. 
 
 As a result of these tests, it would appear that Specially 
 Denatured Formula No. 1 and Completely Denatured For- 
 mula No. 1 are more suitable for cutting shellac than the other 
 three. It would also appear that shellac should be cut in ap- 
 paratus containing very little if any metal. It would further 
 appear that shellac should be stored preferably in glass con- 
 tainers. ‘Terne plate containers have also proved quite satis- 
 factory and are doubtless superior to tin plate containers. 
 
CHAPTER XXX 
 
 BITUMINOUS PAINTS, VARNISHES, CEMENTS AND AUTOMOBILE 
 BLACK BAKING ENAMELS 
 
 During the past five years the use of bituminous substances 
 for cold application as protective coatings has increased con- 
 siderably. This has resulted in an urgent demand for speci- 
 fications and methods for analyzing and testing them. Here- 
 tofore, reliable methods have not been available. The follow- 
 ing descriptions and methods, many of which were prepared 
 for this volume by E. H. jevsguen formerly of the Bureau of 
 Standards, are to be highly recommended. 
 
 Bituminous compositions for cold application can be di- 
 vided into paints, coatings, varnishes, japans, and plastic 
 cements. 
 
 Bituminous Paints.—Bituminous paints are generally mix- 
 tures of a bituminous material and a volatile solvent which 
 are of brushing consistency and which dry and harden by the 
 evaporation of the volatile solvent. They may contain min- 
 eral filler and pigment and small amounts of fatty matter. The 
 term, paint, as defined by the A. 8. T. M. is, however, misap- 
 plied to these materials except in the few instances where pig- 
 ment is added. 
 
 Bituminous paints are marketed under various names but 
 the most important kinds can be classed as dampproofing and 
 roofing paints. Dampproofing paints are used almost exelu- 
 sively on masonry and concrete to prevent the absorption or 
 penetration of moisture and are rarely exposed to the weather, 
 being protected in some manner. The two most common 
 kinds are stone backing and plaster bond. 
 
 Stone backing is a solution of a bituminous material in a 
 volatile solvent used for coating all surfaces except the ex- 
 posed face of cut stone, concrete blocks, ete., to prevent stain- 
 ing, efflorescence, or other discoloration of the exposed face. 
 It is of heavy brushing consistency, invariably dries to a tough 
 flexible film free from tackiness and which will not chip or 
 flake off in handling. They are composed either of asphaltic 
 or coal tar materials. 
 
 Plaster bond is a solution of a rather soft bituminous sub- 
 stance in a suitable volatile solvent for coating the inside of 
 
536 Bituminous Paints 
 
 lene ne ne ene CEASE INE 
 exterior walls of brick, tile, stone, etc., before plastering to 
 prevent staining, etc. Its value as a means of increasing the 
 bond between the plaster and the wall is a matter of question. 
 Plaster bonds are usually made from asphaltic materials and 
 may contain fatty materials, rosin, rosin oil, aluminum stear- 
 ate or oleate or other heavy metal soaps. They are of heavier 
 consistency than stone backings and dry to soft, flexible films 
 which have a tendency to remain permanently tacky or sticky. 
 
 Roofing paints are used for painting metal roofs and for 
 recoating prepared and built-up bituminous roofing. They 
 vary in consistency from those which can be applied with an 
 ordinary paint brush to those which require a stiff bristle 
 dauber or three knot roof brush for application. The former 
 are usually called roofing paints and the latter roof coatings. 
 Roofing paints consist of a bituminous material thinned with 
 a solvent and may contain fine mineral filler or pigments. 
 When pigments are present, some drying or fatty oil may be 
 used. Roof coatings are of heavier consistency than roof 
 paints and contain mineral or other filler usually of a fibrous 
 character in the proportion of about 5 to 15 parts per 100 parts 
 of finished paint. Their common trade name is liquid fibrous 
 asbestos roof coating. Roof paints and coatings may be made 
 from either asphaltic or coal tar materials. When using them 
 for prepared or built-up roofing only asphaltic materials should 
 be applied over asphaltic roofings and only coal tar materials 
 over roofings made with coal tar materials. 
 
 Occasionally paints are encountered which consist of a bitu- 
 minous substance dissolved in carbon bisulphide or carbon 
 tetrachloride. These paints are based on the formula given 
 in the patent of Pearce & Beardsley. Their chief advantage 
 is that they dry rapidly and give relatively thicker dried films 
 than paints of the same consistency made with ordinary sol- 
 vents. 
 
 Bituminous Varnishes.—Bituminous varnishes are mixtures 
 of a bituminous material and fatty oil thinned to a suitable ~ 
 consistency with a volatile solvent which dry partially by the 
 evaporation of the volatile solvent and partially by the oxida- 
 tion of the fatty oil. The toughness and general characteris- 
 tics of the film obtained from bituminous varnishes are in- 
 fluenced by the fatty oil present. Bituminous varnishes may 
 be either long or short oil but those most commonly sold are 
 
Bituminous Paints 537 
 _]—$—$—$— 
 the short oil type with about one part of oil to four, of bitu- 
 minous material. Hard bituminous materials are generally 
 used and include gilsonite, hard native and residual oil as- 
 phalts, glance pitch, manjak, wurtzelite pitch, grahamite, and 
 fatty acid pitches. 3 
 
 Bituminous Japans.—Bituminous japans are mixtures of 
 bituminous materials with or without fatty oil and resins and 
 volatile solvent the drying and hardening of which is brought 
 about by baking. The cheaper grades of japan usually con- 
 sist of a bituminous substance dissolved in a solvent, the bet- 
 ter grades are mixtures of a bituminous substance with fatty 
 acid pitch, drying oils, and resins, with or without small 
 amounts of pigment. Most black insulating varnishes and 
 Brunswick Black are of this character. : 
 
 Bituminous Plastic Cements.—Bituminous plastic cements 
 are mixtures of trowelling consistency of bituminous materi- 
 als with or without fatty oil and volatile solvent and contain- 
 ing about 15 to 40 parts of filler, generally of a fibrous charac- 
 ter, per 100 parts of cement. They are applied in thick layers 
 and usually dry to tough coatings which remain plastic for 
 long periods. They are made either from asphaltic or coal 
 tar materials and the same precautions should be taken in 
 their use on bituminous roofing as with roof paints and coat- 
 ings. Pine tar, pine tar oil, and hard wood tar are sometimes 
 used to improve spreading quality and to modify the odor of 
 coal tar materials. 
 
 Constituents oF Biruminovs Paints, VARNISHES, 
 
 Cements, Etc. 
 
 The following materials are generally used in these prod- 
 ucts, although any material entering into the manufacture 
 of oil, paints, varnishes, etc., is likely to be used. 
 
 (1) Bituminous Materials. 
 
 Petroleum Asphalts Glance Pitch 
 
 Trinidad Asphalt Wurtzelite Pitch 
 
 Bermudez Asphalt Coal Var Pitch? © 
 
 Gilsonite. Water Gas Tar Pitch 
 Grahamite Pine Tar and Wood Pitches 
 
 Manjak Fatty Acid Pitches 
 
538 Bituminous Paints 
 
 a 
 
 (2) Fatty and Resinous Materials. 
 
 Linseed Oil Castor Oil 
 China Wood Oil Rosin 
 Cottonseed Oil Fossil Resins 
 Rosin Oil 
 
 (3) Driers. 
 
 Any drier used in oil paints and varnishes. 
 
 (4) Thonners. 
 Petroleum Distillates Pine Oil and Pine Tar Oil 
 
 Coal Tar Distillates Carbon Bisulphide 
 
 Turpentine Carbon Tetrachloride 
 (5) Fillers and Pigments. é 
 
 Asbestos Slate Dust 
 
 Asbestine Silica 
 
 Clay Rag Fibers 
 
 Portland Cement Jute Fibers 
 
 Limestone Dust Paper Pulp 
 
 Gypsum 
 
 Meruops or ANALYSIS AND TEST 
 (A) Volatile and Nonvolatile: 
 
 (1) Materials without filler—Heat a 1.5 to 2 gram sample 
 in a tared metal dish at 105° to 110° C. for three hours. The 
 loss in weight is calculated as volatile. 
 
 (2) Materials with filler—Heat a 3 to 5 gram sample 
 spread out to a thin layer in a tared metal dish at 105° to 
 110° C. for seven hours. The loss in weight is calculated as 
 volatile. 
 
 (B) Separation and Examination of Thinner: 
 
 (1) Low boiling thinners.—Distill 100 grams of the sample 
 with steam at a temperature of 130° C., collecting the distillate - 
 in a separatory funnel. Stop the distillation when 300 ce. of 
 water has distilled. When the distillate has separated into 
 two distinct layers, draw off the water, and examine the dis- 
 tillate for refractive index, specific gravity, soluble in 38 N. 
 sulphuric acid, dimethyl sulphate, or by any other tests neces- 
 sary for its identification. If no pigment or filler is present 
 the residue in the flask may be dried and used for further 
 testing as in paragraph (D). 
 
Bituminous arnt 539 
 
 (2) High boiling thinners.—Distill 100 grams of ‘the sam- 
 ple in a 200 ce. Engler distilling flask at the rate of about one 
 drop per second, avoiding overheating, which may crack the 
 bituminous material. Collect fractions up to 170° C., and 170° 
 to 300° C., at which point the distillation is stopped. In most 
 eases the thinner will all have distilled at a point below 300° C. 
 and the distillation should be stopped when this occurs. The 
 distillates are examined asin (1). The residue in the flask is 
 allowed to cool until vapors are no longer evolved, when it is 
 poured out into a suitable container and, if no pigments are 
 present, preserved for further testing as in paragraph (D). 
 
 (C) Fillers, pigments and free Carbon: 
 
 Separate the fillers, pigments, and free carbon from the ve- 
 hicle by any of the following methods: 
 
 (1) Weigh accurately about 10 grams of the sample into a 
 centrifuge tube. Add about 25 cc. of benzol and stir so as to 
 break up the sample, then add about 25 cc. more solvent and 
 centrifuge until well settled. Decant the supernatant liquid 
 and repeat the extraction twice with 50 ce. portions of benzol 
 and then with a mixture of equal parts of benzol and carbon 
 tetrachloride until the supernatant liquid is colorless. Dry 
 residue in tube at 105° to 110° C. for one hour and weigh. Pre- 
 serve extracts for further examination of vehicle. The in- 
 soluble residue contains the pigment and fillers, and mineral 
 matter occurring naturally in the bituminous materials (7. e., 
 Trinidad and Bermudez asphalts) and free carbon from coal 
 tar pitches. 
 
 (2) Weigh accurately about 5 grams of the sample into a 
 small beaker, add 25 cc. of carbon bisulphide or carbon tetra- 
 chloride or benzol (if an examination of the vehicle is to be 
 made), break up the sample by stirring and allow to stand for 
 15 minutes. Filter through a weighed Gooch crucible, pre- — 
 pared with a medium thick mat of asbestos, or an Alundum 
 crucible using suction if necessary to aid filtration. Wash 
 the residue in the crucible until the washings are colorless, 
 dry in air at room temperature until the odor of carbon bi- 
 Sulphide has almost disappeared, and then for 1 hour at 105° 
 to 110° C. Cool, weigh, and calculate percentage of insolu- 
 ble material. In this method if Trinidad asphalt is present 
 some of the fine mineral matter may pass through into the ex- 
 tract. This can be determined by evavorating the extract, 
 
540 Bituminous Paints 
 denne. ——————e 
 
 burning off the bituminous matter, and weighing the ash ob- 
 tained. 
 
 (3) Weigh the sample into a paper thimble and extract ina 
 Soxhlet or other suitable extractor. . 
 
 Examination of insoluble matter—The insoluble matter 
 (filler, pigment, free carbon) is examined as in the case of oil 
 paints, except as follows: 
 
 (1) Fibrous Filler —Examine mior once pia for mineral 
 wool, rag fibers, jute, paper pulp and asbestos. 
 
 (2) Free carbon from coal tar compositions, m presence of 
 mineral matter containing water of crystallization.—W hen the 
 filler is asbestos, this method gives satisfactory results. Hx- 
 tract about 5 grams of the sample as in ‘‘C’’ and weigh the 
 residue of carbon and asbestos. Now burn off the carbon and 
 weigh. Increase this weight by 14 per cent to compensate for 
 water of crystallization driven off from the asbestos. Calcu- 
 late percentages of free carbon and asbestos. 
 
 (3) For mixtures of free carbon with asbestos and clay.— 
 The following method has been suggested but has not as yet 
 been thoroughly investigated: Extract about 5 grams of the 
 sample as in ‘‘C’’ and weigh the residue. Ignite the residue 
 in a crucible for seven minutes in a current of dry carbon diox- 
 ide (using a Rose crucible cover) with a flame about 20 cm. 
 high, or in a platinum crucible with a tightly fitting cover in a 
 muffle at between 950° and 975° C. for seven minutes. Cool 
 and weigh. The loss in weight is water of crystallization from 
 the filler. Now burn off the carbon, cool, weigh and calculate 
 the loss in weight as free carbon. 
 
 (D) Nonvolatile Vehicle: 
 
 Saponifiable or fatty matter may be determined by either of 
 the following methods. If no pigment or filler is present, the 
 original material may be taken. If pigment or filler is pres- 
 ent, it should be removed as in (C) and the extract containing 
 the nonvolatile vehicle or base should be evaporated to a small 
 volume over a steam bath. 
 
 (1) The following method is essentially that given in ‘‘ As- 
 phalts and Allied: Substances’’—1920, by Herbert Abraham. 
 
 Weigh 5 grams of the original material (or take the evapor- 
 ated extract from 7.5 grams of material obtained as in (C), 
 and dissolve in 50 ce. of benzol using heat, if necessary, to aid 
 
Bituminous Paints — «541 
 ne a 
 solution. Add 5 ce. of dilute nitric acid (1:1) and boil under 
 a reflux condenser for one-half hour to decompose any metallic 
 soaps (7. e., driers, etc.). Add 150 cc. of water, boil under a _ 
 reflux condenser, then transfer to a separatory funnel, draw 
 off the aqueous layer, and repeat extractions with water until 
 all metals are removed. 
 
 To the benzol solution add 30 cc. of a saponifying liquid 
 made by dissolving 100 grams of anhydrous potassium hy- 
 droxide in 500 ce. of 95 per cent ethyl alcohol and diluting to 
 1,000 ee. with 90 per cent benzol, and boil under a reflux con- 
 denser from one-half to one hour. 
 
 Pour the mixture while still warm into a separatory funnel 
 containing 150 cc. of boiling water and 25 cc. of a 10 per cent 
 solution of potassium chloride. Add 250 ce. of benzol, shake 
 vigorously, and allow the funnel to rest quietly in a warm 
 place until the solvent separates. (If an emulsion forms which 
 refuses to separate on standing, add 200 ec. of benzol and 100 
 ec. of 95 per cent ethyl aleohol and stand in a warm place over 
 night). Usually three layers are obtained. Draw off the 
 aqueous solution of the soaps as completely as possible and 
 decant the benzol layer leaving the intermediate layer in the 
 funnel. 7 
 
 Extract the aqueous soap solution with 200 ec. portions of 
 benzol until the benzol extract is colorless. 
 
 Combine the benzol extracts with the layer obtained from 
 the funnel and extract with 100 ce. portions of 50 per cent 
 ethyl aleohol. Add the alcohol extracts of the benzol layer to 
 the intermediate layer in the separatory funnel and extract 
 with benzol until the benzol extracts are colorless. 
 
 Combine the benzol extracts, evaporate, dry at 105° C., and 
 weigh as unsaponifiable. 
 
 Combine the aqueous soap and alcohol extracts and acidify 
 with dilute hydrochloric acid, warm, and extract with benzol. 
 Evaporate the benzol extract, dry at 100° C. and weigh as 
 saponifiable. | 
 
 (2) The following method (B. S. Circular 104, Recom- 
 mended Specifications for Asphalt Varnish) is ‘more rapid 
 and avoids troublesome emulsions. It has not been tried on 
 compositions containing very soft petroleum asphalts, Trini- 
 dad and Bermudez asphalt, or resins, but it gives satisfactory 
 
542 Bituminous Paints 
 
 results on mixtures of fatty oil with hard petroleum asphalts, 
 gilsonite, wurtzelite pitch, and manjak. 
 
 Weigh about 5 grams of the material into a wide-mouthed 
 flask (or take the evaporated extract from 7.5 grams of ma- 
 terial obtained as in (C), add 50 ce. of benzol and 5 grams of 
 silica sand, and heat under a reflux condenser on a steam bath 
 until the material is entirely dissolved. Add 25 ce. of a half 
 normal alcoholic caustic potash solution, and 25 ec. of de- 
 natured alcohol, and continue boiling under the reflux con- 
 denser for one hour. Remove the condenser and evaporate 
 the solution to dryness. 
 
 Add to the residue in the flask 50 ee. of distilled water and 
 heat until the residue is disintegrated. Filter the water solu- 
 tion of the soaps. Repeat this operation with 25 ee. portions 
 of water until the residue is completely ecto and the 
 wash water is clear and colorless. 
 
 Combine the filtrates (the soap solution ue washings), 
 acidify with hydrochloric acid, and heat until the fatty acids 
 and any emulsified asphalt separate and rise to the top, and the 
 water below is clear. 
 
 Cool, transfer to a separatory funnel, and extract three 
 times with 50 ce. portions of ether. Combine the ether ex- 
 tracts and wash with water until free from acid. Filter the 
 ether extracts through paper into a beaker and wash the resi- 
 due on the paper with ether until the washing runs through 
 colorless. EKivaporate the ether solutions to dryness. 
 
 Add 15 ee. of 95 per cent ethyl aleohol to the residue in the 
 beaker and warm on the steam bath. Cool to room tempera- 
 ture and filter through paper into a tared flask or dish. Re- 
 peat this operation with 10 ec. portions of 95 per cent ethyl 
 alcohol until the aleohol remains colorless. Finally wash the 
 residue on the paper with 95 per cent ethyl aleohol until the 
 washings run through colorless. 
 
 Evaporate to dryness on a steam bath and heat for an hour 
 in an oven at 105° C. (221° F.). Cool and weigh. From the 
 weight of the residue in the flask and the weight of the orig- 
 inal sample calculate the precentage of fatty matter. 
 
 (Sometimes the residue obtained after saponification and 
 the evaporation of the benzol and alcohol from the saponify- 
 ing mixture is not completely disintegrated by boiling with 
 water. In that case, extract with water until nothing further 
 
Bituminous Paints 543 
 nS SS Sn Rn RS ER PE SS SS SE SES SEER EAU LE TEESE! 
 dissolves and then dry. Dissolve in benzol, using heat if nec- 
 essary, and wash the benzol solution several times with water. 
 Heat the washings until the odor of benzol has disappeared 
 and add to the soap solution before acidifying). 
 
 Examination of Saponifiable—The saponifiable obtained as 
 above may be separated into fatty and resin acids by method 
 as on page 451 and may be tested for rosin and fatty acid 
 pitch (Test 37b) ‘‘ Asphalt and Allied Substances’’ by Her- 
 bert Abraham—1920. 
 
 Examination of Unsaponifiable—The unsaponifiable should 
 be tested for melting point and fixed carbon. In case the 
 sample contains no pigment, filler, or saponifiable these tests 
 should be made on the nonvolatile obtained as in (A) or in the 
 residue from distillation as in (B). 
 
 For asphaltic materials determine the melting point by the 
 ‘Standard Method of Test for Softening Point of Bituminous 
 Materials Other Than Tar Products’’—D. 36-21, A. 8S. T. M. 
 Standards, 1921, page 739—(Ring and Ball Method). 
 
 For tar products determine the melting point by the ‘‘Stand- 
 ard Method of Test for Softening Point of Tar Products’’— 
 D. 61-20, A. S. T. M. Standards, 1921, page 743—(Cube in 
 Water Method.) 
 
 For tar products having melting points above 77° C, (170.6° 
 F.) use Cube Method in Air—‘‘Asphalts and Allied Sub- 
 stances,’’ by Herbert Abraham—1920, page 516. 
 
 Determine fixed carbon on asphaltic materials by method 
 given in Journal of American Chemical Society, 1899, Vol. 21, 
 page 1116, or ‘‘ Fixed Carbon in Bituminous Materials, Its De- 
 termination and Value in Specifications,’’ by L. Kirschbaum, 
 Hng. Contr. 39, 172 (1913). The fixed carbon obtained from 
 common asphaltic materials is as follows: 
 
 RIO SASPOAIT 65. b ce wwe ee ae elblnes 12. to 14 per cent 
 MOT AOA BHNALL . is.0 cece cc's vole ao v's wes 8 914 to 18 per cent 
 ERMA OPEC go ujs cos cs ip ns bois 8 es wei ee 15 to 22 per cent 
 ETL Ceo wie. ccpieie au woos 4 o's cee © oe + 8s whe 13 ~=to 16 per cent 
 MEMES ., ie ck Fe ees hs ge ve wines eae 10 to 138 per cent 
 EME ar Wiese we eek eee ge 14 ~=to 20 per cent 
 IEEE RIALS Ss ss ease ea ova ass eels Oh eee ls 15 to 25 per cent 
 RTE Biome te 6 8 2 gs Lh walla Oe Re aie Boe 30 ~=6to 55 per cent 
 
 (i) Tests for the Differentiation of Asphaltic and Coal Tar 
 Pitch: 7 
 
 Owing to the prejudice of the buying public against coal tar 
 
544 Bituminous Paints 
 
 paints and cements, brought about by the use of materials of 
 poor quality made from coal tar materials, and the fact that 
 some dealers in asphaltic materials are using these failures as 
 selling arguments, the analyst is often called upon to prove 
 the presence of coal tar materials other than thinners in 
 asphaltic products and vice versa. 
 
 The following tests are useful for this purpose: 
 
 (1) Color of solution of nonvolatile in benzol—Coal tar 
 materials usually give a solution with a yellowish or greenish 
 brown fluorescence. Asphaltic materials give a brown solution 
 without fluorescence. The presence of oily constituents in 
 some asphalts may at times give a fluorescence that might 
 be mistaken for that obtained from coal tar materials. Wood 
 pitches may also give a slight fluorescence. 
 
 (2) Free Carbon—The presence of free carbon indicates 
 the presence of coal tar or coal tar pitch. 
 
 (3) Distillation T’est—Weigh into an iron or copper distill- 
 ing retort 100 grams of the material under examination. Heat 
 very slowly until distillation begins and then distill off the 
 thinner at the rate of about one drop a second. Usually 
 around 200° CG. a point will be reached where the distillate will 
 stop coming over and the temperature will tend to drop. At 
 this point the thinner is usually all removed. Change the re- 
 ceiver and continue distillation so as to crack or destructively 
 distill the bituminous material until the temperature reaches 
 360° C. Note the character of the distillate. Asphaltic ma- 
 terials usually give liquid distillates of a brown or reddish 
 brown color. Coal tar materials usually give solid distillates 
 of orange or reddish color or liquid distillates from which 
 crystals tend to separate. The character of distillates from 
 mixtures of the two materials varies. The presence of fatty 
 oil is recognized by the odor of acrolein. 
 
 The following tests are made on the cracked distillate: 
 
 (a) Specific Gravity of Cracked Distillate at 25° C.— 
 Cracked distillate or asphaltic materials—O.74 to 0.87. Coal 
 tar materials—0.98 to 1.07. Cracked fatty oils lowers the 
 specific gravity. 3 
 
 (b) Sulphonation with 38 N H,SO,. _ 
 
 The following amounts of residue are usually obtained: 
 
Bituminous Paints a. 545 
 
 SITE DIACCTIAIS. . 05 ce ete e ce eeess 0 to 10 per cent 
 OS Se el 0 to 15 per cent 
 OO CNC a min. 80 per cent 
 ME TICCNCS oo. cs oe ct wc ec eet eee eee Oto 5S per cent 
 mati Acid bitches and Fatty Oils............. Oto 5 per cent 
 
 (c) Soluble in Dimethyl Sulphate.—This test may be used 
 but with caution owing to its unreliability in the case of small 
 amounts of either material. 
 
 The distillates from coal tar materials are usually com- 
 pletely soluble in dimethyl sulphate, while those from asphal- 
 tic materials are about 85 per cent insoluble. 
 
 (d) Anthraquinone Test.—Melt the distillate if solid or if 
 it contains solid particles and take about 5 ce. for examination. 
 Cool and add 10 ec. of absolute ethyl alcohol and allow to stand 
 until the solids separate. Decant the liquid and dry the solids. 
 Dissolve in 45 ce. of glacial acetic acid and boil under a reflux 
 condenser for 2 hours. Add drop by drop to the boiling solu- 
 tion, a solution of 15 grams of anhydrous chromic acid dis- 
 solved in 10 ce. of glacial acetic acid and 10 cc. of water. Boil 
 under reflux condenser for two hours, allow to cool and add 
 400 ee. of cold water, and filter off the precipitated anthra- 
 quinone. The crystals of anthraquinone are washed with hot 
 water, then a hot 1 per cent solution of NaOH, and then with 
 hot water. The residue is dried and weighed and the per- 
 centage of anthracene calculated. From 0.25 to 0.75 per cent 
 of anthracene is found in coal tars, and correspondingly larger 
 amounts in coal tar pitches. 
 
 A qualitative test to identify the crystals consists in boiling 
 them with zine dust and caustic soda solution, whereupon an 
 intense red colored solution (Alizarin) is obtained, which de- 
 colorizes in contact with the air. 
 
 This test will serve to identify coal tar materials in asphalt 
 compositions. 
 
 (4) Diazo Reaction—devised by E. Graefe—‘‘ Distinction 
 between Lignite Pitches and Other Pitches,’’ Chem. Zeit. 30— 
 298—(1906), serves to distinguish those bituminous sub- 
 stances containing phenolic bodies from those not containing 
 them, as asphalts. It should be made on the original bitumin- 
 ous substance. In the absence of coal tar materials, this test 
 will establish the presence of wood tars and pitches in asphal- 
 tic mixtures especially with a positive Liebermann Storch 
 reaction. 
 
546 Bituminous Paints 
 
 (F) Physical Tests: 
 
 While the foregoing tests will give some information about 
 the composition and quality of these materials, and their suit- 
 ability for the purpose intended, the following physical tests 
 are at times more valuable for determining the adaptability of 
 a material for a particular use. 
 
 (1) Time of drying or setting on prepared roofing, metal, 
 concrete, ete. 
 
 (2) Heat test at 140° F. 
 
 (3) Exposure test outdoors at angle of 45° to the south for 
 periods varying from one week to a month. 
 
 (4) Baking test. 
 
 (5) Toughness. 
 
 (6) Working Properties. 
 ) Resistance to water, lubricating oil, and acids. 
 (8) Heat test on smoke stack paint at 410° F. 
 ) Adhesion tests. 
 
 Analysis and Specifications for Roof Coatings.—The Fed- 
 eral Specifications Board of the U. 8S. Government has recently 
 issued Specification No. 424, which is not yet available in 
 printed form. This specification covers the purchase of as- 
 phalt fibrous roof coatings intended for the repair and coat- 
 ing of asphalt and metal roofing, and for application to con- 
 crete, masonry, and steel structures as a damp-proof and 
 protective coating over a priming coat of asphalt primer. 
 Believing that this specification, together with the methods 
 of test, will be of general interest to readers of this chapter, 
 the essential details of the specification are given below. 
 
 The coating shall consist of asphaltic materials, with or 
 without fatty oils, thinned with a volatile solvent to a heavy 
 brushing consistency, and asbestos fiber. 
 
 Condition in Container.—The roof coating must be a smooth, 
 homogeneous mixture. It must not separate or liver in the 
 container. 3 
 
 Consistency.—lt shall be of a heavy brushing consistency 
 to insure a film of appreciable thickness and yet not so stiff 
 as to prevent easy application with a 3-knot roof brush at 
 the rate of approximately 1 gallon per 50 square feet over 
 asphalt roofing. : 
 
 Non-volatile Matter.—The roof coating shall yield not less 
 
Bituminous Paints 547 
 $$ eee 
 
 than 60 per cent non-volatile matter when 10 grains are neated 
 in an oven at 105° C. (221° F.) for 24 hours. - | 
 
 Asbestos Fiber—The roof coating shall contain not less 
 than 5 per cent and not more than 15 per cent. of asbestos 
 
 fiber. None of the asbestoss fiber shall be less than Ye inch 
 in length. 
 
 Lime of Setting—Brushed on prepared roofing and metal 
 at the rate of 1 gallon per 50 square feet and exposed in the 
 laboratory, the coating shall set to a tough plastic coating 
 free from stickiness within 24 hours. 
 
 Behavior at 60° C. (140° F.).—When brushed on prepared 
 roofing at the rate of 1 gallon per 50 square feet and dried 
 for 72 hours and then exposed to a temperature of 60° C. 
 (140° F.) for 5 hours the coating shall not slip or sag and shall 
 not be absorbed into the roofing. | 
 
 Loughness——When the test piece. from previous test has 
 cooled to 25° C. bend quickly over a mandrel 10 mm (2/5 inch) 
 
 in diameter. The coating shall not crack or flake from the 
 roofing. 
 
 METHODS OF TESTING 
 
 Condition in Container—Open the container when received 
 at the laboratory and examine its contents. The material 
 must be a smooth, homogeneous mixture and there must not be 
 any separation, caking or livering. 
 
 Non-volatile Matter.—Weigh about 10 grams of the sample 
 in a weighed flat-bottom metal dish about 8 em in diamter, 
 or in a friction top can plug. Heat the dish with its contents 
 im an oven maintained at 105° C. (22 Tee ee ea Go ee 1s) 
 for 24 hours, cool and weigh. From the weight of the residue 
 left in the dish and from the weight of the original sample 
 taken compute the percentage of nonvolatile matter. 
 
 Asbestos Fiber—Weigh from 2 to 5 grams of the coating 
 and transfer to a small beaker. Add 25 to 50 ce of carbon 
 bisulphide, stir until thoroughly mixed and allow to stand 
 for 15 minutes. . 
 
 Filter the solution through a weighed Gooch crucible pre- 
 pared with a medium thick mat of paper pulp or a paper 
 ‘dise, using suction if necessary to aid filtration. Wash the 
 residue in the crucible with cold carbon bisulphide until the 
 washings are colorless, dry the crucible with its contents 
 in air at room temperature until the odor of carbon bisulphide 
 has almost disappeared, and then for 1 hour in an oven at 
 100 to 105° C. (221° F.), cool and weigh. From the weight 
 
548 Bituminous Paints 
 
 of the insoluble matter in the crucible and the weight of the 
 sample taken compute the percentage of the matter insoluble 
 in carbon bisulphide and consider it as asbestos. Separate 
 the layer of insoluble matter obtained from the mat or disc 
 in the crucible and examine portions of it under the micro- 
 scope in order to determine the length of fiber and the presence 
 of material other than fibrous asbestos. Ignite also a weighed 
 portion of the insoluble matter to a red heat for one-half hour, 
 cool and weigh. The residue obtained shall be not less than 
 80 per cent. 
 
 Time of Setting.—Brush the coating at a rate of approxi- 
 mately 1 gallon per 50 square feet on asphalt saturated felt 
 and clean metal and allow to dry in the laboratory. Test the 
 coating at points not less than 272 cm (1 inch) from the top 
 by touching lightly with the finger. The coating is considered 
 to have set throughout to a tough plastic mass free from sticki- 
 ness when gentle pressure of the finger does not move the 
 coating and none of it adheres to the finger. 
 
 Behavior at 60° C. (140° F.).—Prepare test pieces on as- 
 phalt saturated felt as in previous test and allow to dry for 
 79 hours in a well-ventilated room. Suspend the test pieces 
 vertically for 5 hours in an oven maintained at 60° C. (140° 
 F.). On examination at the end of this period the coating 
 shall not show blistering, sagging, or slipping of more than 
 one-quarter of an inch and shall not be absorbed into the felt. 
 
 Toughness.—Cool the test pieces from above to room 
 temperature and bend quickly over a mandrel 10 mm (2/0 
 inch) in diameter. In bending, the felt should be next to 
 the mandrel. The coating shall not crack or flake from the 
 roofing. 
 
 Testing Automobile Black Baking Enamels.—An outline of 
 some of the tests used by a committee of the subdivision on 
 black baking enamels of the Society of Automotive Engineers, 
 in co-operative work carried on during the past three years, 
 is presented below. It is believed that in general these 
 methods will give information of value in determining the 
 relative properties of black baking enamels. 
 
 Consistency.—‘‘The consistency shall be determined by re- 
 ducing the Enamel with Mineral Spirits to a degree that when 
 liberally poured over a No. 22 U.S. Standard Gage Steel panel 
 314 inches wide by 12 inches long at a temperature of 80 deg. 
 Fahr., and allowed to drain in a vertical position for 15 
 minutes and properly baked will have a film thickness of 
 
Bituminous Paints 549 
 a i a 
 between 0.0008 and 0.0010 inches, measured 6 inches from the 
 top of the panel. 
 
 ‘«The panel shall be cleaned to a bright surface by sanding 
 with 7/0 waterproof paper and washing with benzol to remove 
 rust. 
 
 ‘The thickness of the film shall be determined by the micro- 
 scopic method, focusing to top and bottom of film. 
 
 ‘‘The results shall be reported in parts of thinner to parts 
 of enamel required to give specified thickness. 
 
 ‘‘The viscosity of the thinned enamel is to be taken also 
 in a Universal Saybolt Viscosimeter at 80° F. to compare this 
 property with the film thickness. 
 
 ‘“‘The Specific Gravity of the thinned sample at 80° F. shall 
 be determined by Westphal Balance. 
 
 Baked Panels —‘‘In order to determine the correct baking 
 time, three or more panels of the enamel when applied as 
 described above shall be baked at 400° F. This temperature 
 is very important and should be carefully watched. The size, 
 type, kind of heat, and ventilation of baking oven should be 
 reported. One of the panels shall be removed from the oven 
 at the end of each of the following baking periods—(a) 60 
 minutes, (b) 90 minutes, and (c) 120 minutes. The oven shall 
 be at temperature when panels are put in and the time taken 
 immediately the panels are put into the oven. These panels 
 Shall stand over night after baking and then be tested as 
 described below: 
 
 (a) Appearance: 
 
 ‘“The appearance shall be determined on glass panels of the 
 same size as the steel panels. They shall be prepared in the 
 Same manner as the steel panels. The results shall be re- 
 ported as shown on the log sheet. 
 
 (b) Hardness: 
 
 ‘“‘The hardness shall be determined by the Gardner Pencil 
 Test method, reporting the greatest pencil hardness that will 
 not scratch the surface. 
 
 (ce) Elasticity: 
 ‘“The elasticity of the film shall be determined by rapidly 
 
 bending each panel 180° over a rod 14 inch in diameter at 
 the center and noting the cracking at the bend when examined 
 
550 Bituminous Paints 
 
 under a shaded light. Report temperature and humidity at | 
 the time of making the bend test. | 
 
 (d) Kerosene Softening: 
 
 ‘“The enameled panels shall be immersed for 24 hours in 
 kerosene at room temperature. The hardness immediately 
 after removal shall be determined by the Gardner Pencil Test, 
 reporting the greatest pencil hardness that will not scratch 
 the surface. | 
 
 Chemical Composition: 
 
 ‘“The enamels shall be analyzed for: 
 
 (a) Pigment 
 (b) Ash 
 (c) Non-Volatile Content 
 
 ‘The pigment shall be determined by diluting liberally with 
 benzol, settling and filtering or centrifuging, and reporting 
 pigment in per cent by weight. 
 
 ‘The non-Volatile matter shall be determined by drying a 
 sample of from 1.5 to 3.0 grams in a pint friction-top ean lid 
 in an oven for 5 hours at 115 to 120° cent. ; 
 
 Exposure Test: 
 
 ‘The test panels are to be of automobile sheet or strip steel 
 corresponding to hood and fender stock. The panels shall be 
 31% inches wide by 12 inches long by 0.035 inches thick. 
 
 ‘“Three test panels of each enamel are to be furnished using 
 a film thickness of 0.0008 to 0.0010 inches measured 6 inches 
 from the top of the panel after baking. The baking time on 
 each panel shall be as directed above. 
 
 ‘“The panels for the exposure tests shall be labeled as indi- 
 cated so that each panel may be properly identified. The char- 
 acters should be made with a cellulose nitrate material on a 
 sandpapered spot so that they will not rub off or fade out. 
 
 ‘‘The exposed panels are to be examined for: (a) lustre; 
 (b) general appearance; (c) rusting; (d) adhesion; (e) 
 checking.”’ 
 
‘CHAPTER XXXI 
 
 EXAMINATION OF TURPENTINE AND MINERAL SPIRITS 
 
 The standard specifications of the A. 8S. T. M. for these 
 materials are presented in the latter part of this chapter. 
 Some special methods of testing mineral spirits are included 
 below. With this latter product less uniform grading is 
 found in commercial practice than with turpentine. For this 
 reason manufacturers of paint and varnish often experience 
 considerable difficulty in securing uniform and standard types 
 of mineral spirits for their work. Therefore, in addition to 
 the test prescribed in the specifications referred to, it is well 
 for the chemist to make a study of the evaporative value of 
 various grades of mineral spirits submitted. For this purpose 
 a good exterior and a good interior varnish base may be 
 selected, heated, and thinned with about an equal quantity by 
 weight of mineral spirits of the grades being tested. The 
 varnishes may then be applied to weighed glass plates which 
 should be re-weighed every fifteen minutes for a period of two 
 hours. The loss in volatile is then reported. Mineral spirits 
 having large quantities of heavy, non-volatile ends will readily 
 be noticed. The body of the varnishes and the brushing, flow- 
 ing and leveling properties should also be ascertained by 
 further tests. 
 
 Solvent Properties —It is also advisable to make a test to 
 determine the solvent properties of the mineral spirits, and 
 for this purpose it is customary to use varnish bases as re- 
 ferred to above, thinning down with equal parts by weight of 
 the mineral spirits being tested. The reduced samples are gen- 
 erally placed in 4 oz. oil bottles and inspected for a period 
 of 10 to 12 days to watch for the development of suspended 
 matter, turbidity or other precipitated products due to lack 
 of solvent properties of the thinner. Distillation of a sample 
 of the mineral spirits and examination of the various frac- 
 tions for solvent properties often gives much information of 
 value. 
 
 One of the most useful materials to include in a test for the 
 solvent character of mineral spirits is extremely heavy-bodied 
 linseed oil. Apparent solution takes place when such an oil is 
 thinned with mineral spirits, but after standing, the oil is often 
 
BEY Turpentine and Mineral Spirits 
 thrown out, showing that the preliminary solution was only of 
 a suspension colloid type. The continued addition of incre- 
 ments of mineral spirits to a volume of heavy-bodied oil, until 
 the precipitation point is reached, will give relative data of al- 
 most quantitative character. Since such oils are often used 
 in flat finishes which sometimes contain in the liquid portion as 
 
 Begins to cloud Separation occurs 
 Thinner a ae 
 
 Oil Thinner Oil Thinner 
 Die ee 2 1 3 
 E.. ae. Men Re GOES one Heel a) a” 1 8 i: 8 
 eae 1a hi ay uate eae Ri ne No cloudiness or separation at any dilution. 
 Git 1 | 10 1 | 11 
 tae si poled ete ta dan MON ae No cloudiness or separation at any dilution. 
 ta : y Pee Me ete gb e pie. 1 a 1 4 
 Ki aia 1 3 1 4 
 lid hel 1 8 1 10 
 
 high as 75 per cent of mineral spirits, the throwing out of the 
 oil would be a very objectionable feature. 
 
 There appears to be a great difference in the action of the 
 various brands of mineral spirits with bodied oils, especially 
 blown oils. Turpentine usually mixes well in all proportions 
 with such oils. When equal portions of the same oil and min- 
 eral spirits are mixed, some samples show a turbid and milky 
 appearance. As the quantity of thinner is increased the tur- 
 bidity increases until separation occurs. While in some grades 
 cloudiness occurs even at low dilution, other samples may not 
 become turbid until much greater dilutions have been reached. 
 Some may remain clear when mixed in practically any propor- 
 tion. Where there is only a slight turbidity at first, complete 
 separation may occur on standing. The accompanying chart 
 shows the dilutions at which cloudiness and oil separation first 
 occurred when thinning a very heavy grade of blown and heat- 
 treated linseed oil with several commercial grades of mineral 
 spirits. Figures indicate parts by weight. 
 
 -- wee 
 
Turpentine and Mineral Spirits 553 
 
 In making these dilution tests a tall narrow beaker may be 
 conveniently used. <A fair idea of the miscibility of the thinner 
 may be obtained in the following manner: Weigh out a small 
 quantity of bodied oil, say 5 or 10 grams, in the beaker. Then 
 add an equal quantity of the mineral spirits to be tested. Stir 
 with a glass rod, noting the readiness with which the two 
 layers mix. Some samples will show a cloudiness at once, 
 which may, however, disappear as the two mix. Others may 
 mix perfectly clear. Add successive portions of the thinner, 
 stirring after each addition and noting carefully the appear- 
 ance, readiness of mixing, etc. Determine the point at which 
 a permanent milkiness results. After the addition of one or 
 two more portions, part or all of the oil will usually separate 
 on standing a short time. 
 
 While the quantity of thinner required to throw out the oil 
 may in many cases be far in excess of the proportion ordi- 
 narily used, yet in consideration of the fact that the products 
 which exhibit the greatest tendency to become turbid are most 
 likely to separate on standing, it seems advisable to employ 
 only those which stand up best under the dilution test. 
 
 Run Kauri Solubility Test—Another test of importance can 
 be made with standardized run Kauri gum such as is used for 
 testing the elasticity of varnish. The preparation of this is 
 outlined in the specifications for spar varnish in the back of 
 this book. The Run Kauri is dissolved in an equal quantity 
 by weight of re-distilled turpentine. To 50 ce. of the mixture, 
 mineral spirits is gradually added with occasional shaking 
 until a cloud forms. An improvement in the test is to use a 
 mixture of 100 ce. of the Run Kauri solution and 100 ce. of 
 heavy bodied oil, subsequently thinning down a determined 
 volume of this mixture with the mineral spirits under exam- 
 ination. For this purpose, however, a standard grade of 
 heavy bodied oil should be used in every laboratory, otherwise 
 different results would be obtained. 
 
 Whether the thinner is derived from an asphaltum base or 
 paraffin base petroleum is of little importance so long as it con- 
 forms to other requirements. The asphaltum base petroleums 
 are said to possess, in general, greater solvent power due to 
 the presence of a larger proportion of cyclic hydrocarbons. If 
 desired, the proportion of the latter may be estimated com- 
 
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Turpentine and Mineral Spirits 555 
 
 paratively by the Formolit Reaction (Nastjukoff Test) ).* 
 But practical tests, such as those described herein must remain 
 the deciding ones in determining the value of a given thinner. 
 
 Sulphur Content.—Another very important observation to 
 be made on mineral spirits is the effect of the sulphur content 
 upon the color of paints or varnishes in which they are used. 
 The white lead test that has in the past been used for this pur- 
 pose will not very often disclose the presence of objectionable 
 sulphur compounds. The Doctor test is not sensitive and is 
 rather difficult to perform. Varnishes, however, which con- 
 tain metallic driers, such as lead, in organic solution, will 
 rapidly become darkened when thinned with mineral spirits 
 containing certain objectionable sulphur compounds. Some 
 grades of mineral spirits, for instance, may contain as high as 
 1% per cent of sulphur. If this sulphur is in a certain fixed 
 form, it may not darken with lead compounds in solution. 
 Other grades of mineral spirits, which contain even very small 
 traces of sulphur in readily available form, will quickly darken 
 organic lead solutions. One test which the writer has used is 
 as follows: 7 
 
 Make up a varnish base by fusing 100 grams of rosin 
 with five-tenths of a gram of lead oxide. If desired, co- 
 balt, manganese, copper and other oxides that are liable 
 to be present in cooked varnish, may also be included 
 in small amounts. This is then used as the base for 
 test. 100 grams of the product is heated and thinned 
 down with 100 grams of the mineral spirits to be tested, 
 and held at a temperature of about 350° F. for 30 
 minutes, preferably in a reflux condenser. Darkening 
 will occur with those grades of mineral spirits having 
 reactionable sulphur content. 
 
 Probably the most graphic test for sulphur in mineral spirts | 
 is the copper strip test. This is made by placing in a carbon 
 tube about 15” long and 14” in width, a strip of copper 14” wide 
 and 2” long. Sufficient mineral spirits is added to completely 
 cover the copper. The tube is then immersed in an oil bath 
 which is run up to 350° F. or to such temperature as will cause 
 the mineral spirits to boil. The test should be run for a period 
 
 *See Holde-Mueller. Examination of Hydrocarbon Oils and Saponifiable 
 Fats, John Wiley & Sons, p. 388. 
 
556 Turpentine and Mineral Spirits 
 
 of 30 minutes, and the effect on the copper strip observed. If 
 only a slight bloom or fluorescence is shown, the mineral spirits 
 should be acceptable. If blackening of the strip is shown, the 
 mineral spirits should be looked upon as unsatisfactory for 
 certain varnishes. This test will show a blackened condition 
 of copper if the mineral spirits contains even .04 per cent of 
 reactive sulphur. 
 
 It has been proposed to run the copper strip test at a higher 
 temperature, keeping the strip in a flask of boiling mineral 
 spirits, connected with a reflux for ten minutes and then dis- 
 tilling off about 96 per cent of the mineral spirits. 
 
 Distillation Range.—Better control of boiling range by the 
 refiner will enable him to deliver a more satisfactory product 
 to the consumer. Mineral spirits conforming to Federal 
 Specifications (see back part of this volume) while generally 
 satisfactory for thinning paste paints, would be of much 
 greater value for thinning varnishes if of a narrower range in 
 distillation. The Philadelphia Paint Production Men’s Club 
 suggests the following range: 
 
 Distillate below 150° C. not over 5%. 
 Distillate below 180° C. not less than 50%. 
 Distillate below 220° C. not less than 97%. 
 
 A. 8S. T. M. STANDARD SPECIFICATIONS FOR GUM SPIRITS 
 OF TURPENTINE AND STEAM-DISTILLED WOOD 
 TURPENTINE 
 
 1. These specifications apply both to spirits of turpentine made from gum 
 (oleoresin) from a living tree, commonly known as “gum spirits” or “turpen- 
 tine” and to steam-distilled wood turpentine, which is distilled with steam 
 from the oleoresin within the wood. When ordering under these specifications, 
 the purchaser shall specify whether (a) gum spirits of turpentine or (0) 
 steam-distilled wood turpentine is desired. 
 
 I. PROPERTIES AND TESTS 
 
 2. Gum spirits of turpentine or steam-distilled wood turpentine shall be 
 pure and conform to the following requirements : 
 
 8. It shall be clear and free from suspended matter and water. 
 
 4. The color shall be “Standard” or better. 
 
 5. The odor shall be mild, aromatic and characteristic of the variety of 
 turpentine specified and, if desired, shall conform to the odor of the sample 
 agreed upon. 
 
 6. Other properties shall be as follows: 
 
Turpentine aud Mineral Spirits 557 
 
 Maximum Minimum 
 
 eee aVity 15.5° /15.5° Con... cee ye ede. 0.875 0.860 
 Buereraverniex At ZOO. . kw kee ce cae 1.478 1.465 
 Residue after polymerization with 38 N H,SO,: 
 
 SPENT TCCONG os 6. cc te os sce wesc twee 2.0 eee cape 
 
 peereetave index At 20° CO... . wk cet eee ee 1.500 
 
 Consistency shall be viscous. 
 
 Color shall be straw or darker. 
 Initial boiling point at 760 mm. pressure...... 160° C. 1502 C. 
 Distilling below 170°C. at 760 mm. pressure, 
 
 Sia eens wigs oe a ale sre el sles cee ie 0 9s eee es 90 
 
 Il. METHODS OF TESTS 
 7. The sampling and methods of testing shail be conducted in accordance 
 with the Standard Methods of Sampling and Testing Turpentine (Serial 
 Designation: D 233) of the American Society for Testing Materials.* 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
 DESTRUCTIVELY DISTILLED WOOD TURPENTINE* 
 
 1. These specifications apply only to destructively-distilled wood turpentine 
 obtained in the destructive distillation of resinous wood. 
 
 I. PROPERTIES AND TESTS 
 2. The destructively distilled wood turpentine shall be pure and conform 
 to the following requirements: 
 3. It shall be clear and free from suspended matter and water. 
 4. The color shall be “Standard” or better. 
 5. The odor shall be characteristic of destructively-distilled wood turpen- 
 tine and, if desired, shall conform to the odor of the sample agreed upon. 
 
 6. Other properties shall be as follows: 
 MAXIMUM MINIMUM 
 
 PUMA OTAVILY, 10.0 /1D.5° Goceks ecco case cece 0.875 0.860 
 Hemuactiye index at 20° C., D line....... ....... 1.4838 1.463 
 Residue after polymerization with 38 N H).SO,: 
 
 Pen e CTI CON (0). ic sve cn 0's ce oe 0 ses ese 2.0 nie A 
 
 Peetrreniye. INGex at 20° ©... 6. sic ce wes cies CALE 1.480 
 Initial boiling point at 760 mm. pressure..... iby igs Oe 150° C., 
 Distillation below 170° C. at 760 mm. pressure, 
 
 REI AAMT ae oia's bos cv ace Sok Oe eV ac <i s's sae 60 
 Distilling below 180° C. at 760 mm. pressure, per 
 
 RE Te APs any 'c ike sos in 605,84 0! 0% so 8 wale See 0 Seats 90 
 
 -II. METHODS OF TEST 
 7. The sampling and methods of testing shall be conducted in accordance 
 with the Standard Methods of Sampling and Testing Turpentine (Serial 
 Designation: D 233) of the American Society for Testing Materials. 
 
 A. 8S. T. M. STANDARD METHODS OF SAMPLING AND 
 TESTING TURPENTINE 
 
 I. DETECTION AND REMOVAL OF SEPARATED WATER 
 1. Draw a portion by means of a glass or metal container with a removable 
 stopper or top, or with a “thief,” from the lowest part of the container, or by 
 
 * A.'S.T.M. Standards Adopted in 1926 
 
558 Turpentine and Mineral Spirits 
 | a 
 opening the bottom valve of the perfectly level tank car. If water is found 
 to be present, draw it all out, record the quantity, and deduct it from the 
 total volume of liquid delivered. 
 
 ¥ Il. SAMPLING 
 2. The method of sampling given under (a) shall be used whenever feasible. 
 When method (a) is not applicable, method (0b), (c), or (d) shall be 
 used according to the special conditions that obtain. 
 (a) While Loading Tank Car or While Filling Containers for Shipment.— 
 Samples shall be drawn by the purchaser’s inspector at the discharge pipe 
 where it enters the receiving vessel or vessels. The composite sample shall 
 
 be not less than 5 gal. and shall consist of small portions of not more than 1 
 
 qt. each taken at regular intervals during the entire period of loading or 
 filling. 
 
 The composite sample thus obtained shall be thoroughly mixed and from 
 it three samples of not less than 1 qt. each shall be placed in clean, dry, glass 
 bottles or tin cans, which shall be nearly filled with the sample and securely 
 stoppered with new, clean corks or well-fitting covers or caps. These shall 
 be sealed and distinctly labeled by the inspector; one shall be delivered to the 
 purchaser, one to the seller, and the third held for check in case of dispute. 
 
 (vb) From Loaded Tank Car or Other Large Vessel.—The composite sample 
 taken shall be not less than 5 gal. and shall consist of numerous small samples 
 of not more than 1 qt. each taken from the top, bottom, and intermediate points 
 by means of a metal or glass container with removable stopper or top. This 
 device, attached to a suitable pole; is lowered to the various desired depths, 
 when the stopper or top is removed and the container allowed to fill. The 
 sample thus obtained is handled as in method (a). 
 
 (c) Barrels and Drums.—Barrels and drums shall be sampled after gaging 
 the contents. Five per cent of the packages in any shipment or delivery shall 
 be represented in the sample. Thoroughly mix the contents of each barrel 
 to be sampled by stirring with a clean rod and withdraw a portion from about 
 the center by means of a “thief” or other sampling device. The composite 
 
 sample thus obtained shall be not less than 3 qt., shall consist of equal portions 
 
 of not less than } pt. from each package sampled, and shall be handled as in 
 method (a). Should the inspector suspect adulteration, he shall draw the 
 samples from the suspected packages. 
 
 (d) Small Containers, Cans, etc., of 10 gal. or Less.—These shall be 
 sampled, while filling, by method (a) whenever possible; but in case this is 
 impossible the composite sample taken shall be not less than 3 qt. This shall 
 be drawn from at least five packages (from all when fewer), and in no case 
 from less than 2 per cent of the packages. The composite sample thus taken 
 shall be thoroughly mixed and subdivided as in method (a). 
 
 Ill. LABORATORY EXAMINATION 
 
 8 Examine to determine compliance with the specifications. 
 
 4. Fill a 200-mm. perfectly flat-bottomed colorimeter tube, graduated in 
 millimeters, to a depth of from 40 to 50 mm. with the turpentine to be ex- 
 amined. Place the tube in a colorimeter and place on it or under it a No. 2 
 yellow Lovibond glass. Over or under a second graduated tube in the colori- 
 meter, place a No. 1 yellow Lovibond glass and run in the same turpentine 
 until the color matches as nearly as possible the color in the first tube. Read 
 
 ayer FN 
 
 sa IN eT i A a A ak pall cath Shells) ied “Dg 
 
Turpentine and Mineral Spirits 559 
 
 the difference in depth of the turpentine in the two tubes. If this difference 
 is 50 mm. or more, the turpentine is “Standard” or better. 
 
 5. Determine odor by comparison with the agreed-upon sample which shall 
 have been kept in the dark in completely filled well-stoppered bottles and free 
 from separated water. In case no agreed-upon sample is available, compare 
 with samples of known purity that have been kept in filled stoppered bottles 
 in the dark and are free from separated water. 
 
 -6, Determine specific gravity at 15.5 /15.5° C., by any convenient method 
 that is accurate within 2 points in the fourth figure. 
 
 7. Determine refractive index at 20° C. with an accurate instrument. When 
 the refractive index is determined at any other temperature, the readings 
 obtained shall be corrected to 20° C. by adding to or by subtracting from the 
 actual reading 0.00045 for each degree Centigrade that the temperature at 
 which the determination was made is, respectively, above or below 20° C. 
 
 8. Distillation Apparatus.*—(a) Condenser.—The type of apparatus is 
 shown in Fig. 194, or may be the apparatus described in the Tentative Method 
 
 we 
 
 7-7 Se: 
 
 ——— 
 
 FIGURE 194 
 Distillation Apparatus. 
 
 * The flask, condenser, shield, ring support and hard asbestos board, gas 
 burner or electric heater, described in the Tentative Method of Test for 
 Distillation of Gasoline, Naphtha, Kerosene and Similar Petroleum Products 
 (Serial Designation: D 86-26 T) of the American Society for Testing Ma- 
 terials, Proceedings, Am. Soc. Testing Mats., Vol. 26, Part I (1926), which are 
 essentially the same as the equipment herewith described, may be employed 
 in the distillation test wherever it is available. 
 
560 Turpentine and Mineral Spirits 
 
 aaa, 
 
 of Test for Distillation of Gasoline, Naphtha, Kerosene and Similar Petroleum 
 Products (Serial Designation: D 86-26 T) of the American Society for 
 Testing Materials,* substituting for the thermometer there described an 
 immersed thermometer, such as is described below. 
 
 (b) Flask—Comparable results can be obtained only by using flasks of 
 the same dimensions. The distilling flask used shall be the standard Engler 
 flask, as used for petroleum distillation, having the following dimensions: 
 Diameter of bulb, 6.5, cm.; cylindrical neck, 15 cm. long, 1.6 cm. internal 
 diameter ; side or vapor tube, 10 em. long, 0.6 cm. externa] diameter, attached 
 to neck at an angle of 75 deg., so that when the flask contains its charge of 
 100 ec. of oil the surface of the liquid shall be 9 em. below the bottom of the 
 junction of the side tube and neck. 
 
 (c) Support for Flask.—Support the flask on a plate of asbestos 20 cm. in 
 diameter, having an opening 4 cm. in diameter in its center, and heat with 
 an open flame. Surround the flask and burner with a shield to prevent 
 fluctuation in the temperature of the neck of the flask. Or, support the flask 
 in a metal cup, 15 to 20 cm. in diameter, containing high-boiling mineral oil 
 or glycerin and fitted with a concave cover having in the center a circular 
 opening 54 to 6 em. in diameter. In all cases take the necessary precautions 
 to prevent fluctuation in temperature in the neck of the flask. 
 
 (d) Thermometer.—The thermometer used for turpentine distillation shall 
 conform to the following specifications: 
 
 It shall be graduated from 145 to at least 200° C. in 0.2° intervals. Length, 
 bottom of thermometer to 175° C. mark, not more than § nor less than 6.5 cm. 
 Length, top of bulb to 145° C. mark, not less than 1.5 cm. Length, 145 to 175° 
 C. mark, not more than 6 cm. Thermometers graduated above 200° C. may be 
 used, provided they also comply with the foregoing requirements. 
 
 The thermometer shall be made of suitable thermometric glass and thor- 
 oughly annealed, so that the scale errors will not increase after continued 
 heating. 
 
 The thermometer shall be filled above the mercury with an inert gas, with 
 sufficient pressure above the mercury column to prevent breaking of the 
 column. It shall have a reservoir at the top, so that the pressure will not 
 become excessive at the highest temperature. 
 
 Every fifth graduation shall be longer than the intermediate ones, and 
 the marks shall be numbered at each interval of 5° C. The graduation marks 
 shall be clear-cut and fine and the numbering clear-cut and distinct. 
 
 The error at any point on the scale shall not exceed + 0.5° C. when tested 
 for total immersion of the mercury column. é 
 
 (e) Receiving Cylinder.—Collect the distillate in an accurately graduated 
 50 or 100-ce. cylinder. The so-called normal or precision cylinder of 50 cc. 
 capacity, having an internal diameter of 1.5 cm. and graduated in 0.2 ce. is 
 preferred. If a cylinder with larger inside diameter is used, a pasteboard 
 cover should be placed over the top and surround the condenser tube. 
 
 9. Operation.—Place 100 cc. of the turpentine and several small pieces of 
 pumice (or glass) in the distilling flask, fit the thermometer so that the top 
 of the mercury bulb is level with the bottom of the side tube, and the 175° C. 
 
 * Proceedings. Am. Soc. Testing Mats., Vol. 26, Part I (1926); also 1926 
 Book of A.S.T.M. Tentative Standards. 
 
 Th Ree 
 
 gars rick ae! 
 
Turpentine and Mineral Spirits 561 
 
 mark is below the cork. Place the flask in position on the asbestos board or 
 oil bath and connect with the condenser. Apply the heat cautiously at first, 
 and, when distillation begins, regulate the heat so that the turpentine distills 
 at the rate of not less than 4 nor more than 5 cc. per minute (approximately 
 two drops per second). The initial boiling point is the thermometer reading 
 at the instant when the first drop falls from the end of the condenser. Dis- 
 continue distillation when the temperature reaches 170° C., or an equivalent 
 thereof, depending on the atmospheric pressure, as described in Section 10; 
 let the condenser drain and read the percentage distilled. 
 
 The percentage distilled below successive selected temperatures and the 
 temperature at which each successive 10 cc. distills may also be determined, 
 if desired, making the necessary correction of the temperature for variations 
 in atmospheric pressure. 
 
 10. Correction for Variation in Atmospheric Pressure.—Since distillation 
 results are comparable only when obtained under exactly the same pressure 
 conditions, turpentine shall be distilled at that pressure which, at room 
 temperature, is equivalent to a pressure of 760 mm. of mercury at O° C., 
 Whenever the atmospheric pressure after correcting to O° C. is other than 
 
 CORRECTION TO BAROMETER READINGS.! 
 
 (From Circular F, Instrument Division, Weather Bureau, U. S. Department of 
 
 Agriculture.) 
 Texapera- Observed Reading of Barometer, mm. 
 ture, 
 deg. Cent. 
 
 650 | 660 | 670 | 680 | 690 | 700 | 710 | 720 | 730 | 740 | 750 | 760 | 770 | 780 
 15.0 1.56 | 1.59 | 1.61 | 1.64 | 1.66 | 1.69 | 1.71 | 1.74 | 1.76 | 1.78 | 1.81 | 1.83 | 1.86 | 1.88 | 1.91 
 16.0 1.67 | 1.69 | 1.72 |.1.75 | 1.77 | 1.80 | 1.83 | 1.85 | 1.88 | 1.90 | 1.93 | 1.96 | 1.98 | 2.01 | 2.03 
 17.0 1.77 | 1.80 | 1.83 | 1.86 | 1.88 | 1.91 | 1.94 | 1.97 | 1.99 | 2.02 | 2.05 | 2.08 | 2.10 | 2.13 | 2.16 
 18.0 1.88 | 1.91 | 1.93 | 1.96 | 1.99 | 2.02 | 2.05 | 2.08 | 2.11 | 2.14 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 
 19.0 1.98 | 2.01 | 2.04 | 2.07 | 2.10 | 2.13 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 } 2.32 | 2.35 | 2.38 | 2.41 
 20.0 2.08 } 2.12 | 2.15 } 2.18 | 2.21 | 2.25 | 2.28 | 2.31 | 2.34 | 2.388 | 2.41 | 2.44 } 2.47 | 2.51 | 2.54 
 21.0 2.19 | 2.22 | 2.26 | 2.29 | 2.32 | 2.36 | 2.39 | 2.43 | 2.46 | 2.50 | 2.53 | 2.56 | 2.60 | 2.63 | 2.67 
 22.0 2.29 | 2.33 | 2.36 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.61 | 2.65 | 2.69 | 2.72 | 2.76 | 2.79 
 23.0 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 | 2.73 | 2.77 | 2.81 | 2.84 | 2.88 | 2.92 
 24.0 2.50 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 | 2.73 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 
 250 2.60 | 2.64 | 2.68 | 2.72 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 | 3.09 | 3.13 | 3.17 
 26.0 2.71 | 2.75 | 2.79 | 2.83 | 2.88 | 2.92 | 2.96 | 3.00 | 3.04 | 3.09 | 3.13 | 3.17 | 3.21 | 3.26 | 3.30 
 27.0 2.81 | 2.85 | 2.90 | 2.94 | 2.99 | 3.03 | 3.07 | 3.12 | 3.16 | 3.20 | 3.25 | 3.29 | 3.34 | 3.38 | 3.42 . 
 28.0 2.91 | 2.96 | 3.00 | 3.05 | 3.10 | 3.14 | 3.19 | 3.23 | 3.28 | 3.32 | 3.37 | 3.41 | 3.46 | 3.51 | 3.55 
 29.0 | 3.02 | 3.06 | 3.11 | 3.16 | 3.21 | 3.25 | 3.30 | 3.35 | 3.39 | 3.44 | 3.49 | 3.54 | 3.58 | 3.63 | 3.68 
 30.0 3.12 | 3.17 | 3.22 | 3.27 | 3.32 | 3.36 | 3.41 | 3.46 | 3.51 | 3.56 | 3.61 | 3.66 | 3.71 | 3.75 | 3.80 
 31.0 3.22 | 3.27 | 3.32 | 3.37 | 3.43 | 3.48 | 3.53 | 3.58 | 3.63 | 3.68 | 3.73 | 3.78 | 3.83 | 3.88 | 3.93 
 32.0 3.33 | 3.38 } 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.69 | 3.74 | 3.79 | 3.85 | 3.90 | 3.95 | 4.00 | 4.05 
 33.0 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.70 | 3.75 | 3.81 | 3.86 | 3.91 | 3.97 | 4.02 | 4.07 | 4.13 | 4.18 
 
 1 These corrections apply to a mercurial barometer with brass scale. They can, however, be used fora mercurial 
 barometer with glass scale, since the érrors introduced thereby are negligible as applied to the work contemplated in 
 _ this circular. For exact correction to be applied to such a barometer see Smithsonian Physical Tables, p. 119 (1914). 
 An aneroid barometer should not be relied on. : , . 
 
 For barometer readings below 640 mm. the correction can be interpolated, since the difference at any particular 
 temperature for each 10 mm. variation in barometer reading is practically constant. 
 
 760 mm., a correction shall be made. Since alteration of the pressure in the 
 distilling system requires rather complicated apparatus, it is simpler to alter 
 the temperature observation points to correspond to the prevailing pressure. 
 
 To determine what the atmospheric pressure at the prevaiilng room tem- 
 perature, or at the temperature of the barometer, would be at 0° C., read the 
 barometer and the thermometer alongside when about to begin distillation. 
 Referring to Table above, under the column nearest the observed pressure 
 reading and on the line nearest the observed temperature of the barometer 
 
562 Turpentine and Mineral Spirits 
 
 will be found the correction which must be subtracted from the observed 
 pressure reading to obtain the equivalent, or true, reading at 0° C. 
 
 The distilling temperature of turpentine is affected plus (+) or minus 
 (—) 0.057° C. for each millimeter variation of the barometer above or 
 below the normal 760 mm. at 0°C.* If the barometer reading, after correct- 
 ing to 0° C., is below 760 mm., the turpentine will distill at a slightly lower 
 temperature than under normal pressure. Therefore, the temperature re- 
 corded at the beginning of distillation (and any others observed during the 
 course of the distillation) must be corrected to get its equivalent at normal 
 pressure, The final temperature observation point (170° C., Section 9) must 
 be altered accordingly to get its equivalent at the pressure (corrected to 0° 
 C.) at which distillation is made. 
 
 For example, if the barometer reading, after correcting to O° C., is 
 750 mm., the correction of the observed initial distilling temperature will be 
 0.057 X 10 = 0.6° C. approximately. If the reading of the thermometer when 
 the turpentine begins to distill is 155.6° C., the corrected initial distilling 
 temperature will be 155.6° + 0.6° = 156.2° C. Furthermore, the temperature 
 observation point at end of distillation (170° C. at 760 mm.) must be altered 
 to the same extent. Since the turpentine is distilling 0.6° C. below what it 
 would at normal pressure, distillation must be discontinued at 0.6° C. below 
 the specified limit of 170° C. to determine the percentage distilling below 
 170° C, 
 
 If the barometer reading corrected to 0° C. is above 760 mm., subtract the 
 temperature correction from the observed thermometer reading to determine 
 the initial distilling point, and continue distillation to 170° C. plus the correc- 
 tion to determine the percentage distilling below 170° C. 
 
 11. (a) Place 20 ce. of 38 N (equivalent to 100.92 per cent H,SO,) sulfuric 
 acid in a graduated, narrow-necked Babcock flask, stopper, and place in ice 
 water to cool. Add slowly—from a pipette, 5 ce. of the turpentine to be 
 examined. Gradually mix the contents, keeping warm, but being very careful 
 that the temperature does not rise above 60° C. When the mixture no longer 
 warms up on shaking, agitate thoroughly and place the flask in a water bath 
 and heat at 60 to 65° C. for not less than 10 minutes, keeping the contents 
 of the flask thoroughly mixed by vigorous shaking for one-half minute each 
 time, six times during the period. Do not stopper the flask after the turpen- 
 tine has been added, as it may explode. Cool to room temperature, fill the 
 flask with concentrated sulfuric acid until the unpolymerized oil rises into 
 
 the graduated neck and centrifuge from four to five minutes at not less than ~ 
 
 1200 r. p. m., or for 15 minutes at 900 r. p. m., or allow to stand, lightly 
 stoppered, for 12 hours. Calculate the percentage, note the consistency and 
 color, and determine the refractive index (at 20° C.) of the unpolymerized 
 residue. 
 
 (b) Reagent for Testing.—In a weighed glass-stoppered bottle (the regu- 
 lar 2%-liter acid bottle is of a convenient size) mix ordinary concentrated 
 sulfuric acid (sp. gr. 1.84) with fuming sulfuric acid. If the fuming acid 
 used contains 50 per cent excess SO,, the ratio of one part, by weight, of the 
 former to three-fourths of a part, by weight, of the latter will give a mixture 
 
 * Landolt-Biérnstein Physikalisch-Chemische Tabellen, Ed. 4, Table 127, 
 p. 435. 
 
 net ie os aie hw ee 
 
Turpentine and Mineral Spirits 563 
 
 slightly stronger than the required strength. To determine the exact strength 
 of this mixture in terms of H,SO,, weigh exactly, in a weighing pipette of 
 about 10 ce. capacity, approximately 20 g. of the acid. Allow it to flow down 
 the sides of the neck into a 1000-cc. volumetric flask containing about 200 cc. 
 of distilled water. When the pipette has drained, wash all traces of the acid 
 remaining in the pipette into the flask, taking precautions to prevent loss of 
 SO,, and make up to the mark. Titrate 20-ce. portions, drawn from a burette, 
 against half normal alkali. Calculate the concentration in terms of the 
 percentage of H,.SO, in the sample taken. 
 
 In the same way determine the percentage of H.SO, in the stock of ordi- 
 nary concentrated acid (sp. gr. 1.84). From these data calculate the quantity 
 of the latter which must be added to the quantity of mixed acid in the 
 weighed bottle to bring it to a concentration, in terms of H,SO,, of 100.92 
 per cent. 
 
 After adjusting the concentration by the addition of the ordinary sulfuric 
 acid, thoroughly shake the bottle of mixed acid and again determine its concen- 
 tration. The allowable variation is + 90.05 per cent H,SO,. Finally as a 
 check run a polymerization test on gum turpentine known to be pure. The 
 residue should fall below 2 per cent. 
 
 FIGurE 195 
 Acid Bottle and Pipette. 
 
 Special precautions must be taken to prevent dilution of this acid by 
 the absorption of atmospheric moisture. The arrangement shown in Fig. 195 
 is most suitable for storing and delivering measured quantities of this reagent. 
 
564 Turpentine and Mineral Spirits 
 
 With the three-way stop-cocks A and B in the position shown, acid is 
 siphoned into the pipette P, the displaced air passing into R. To empty the 
 
 pipette, A and B are turned to the position shown by the broken lines, air 
 passing in at a. The acid adhering to the walls of the pipette dries this air 
 
 so that when it passes into R&R on again filling the pipette there is no accumu- 
 lation of moisture in the acid remaining in the reservoir. If such arrange- 
 ment is not to be had, the acid should be kept in well-fitting glass-stoppered 
 bottles of not more than one-half liter capacity. 
 
 A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
 PETROLEUM SPIRITS (MINERAL SPIRITS) 
 1. These specifications apply only to petroleum distillates. 
 
 I. PROPERTIES 
 
 2. The material shall conform to the following requirements : 
 
 (a) Appearance.—It shall be clear and free from suspended matter and 
 water. 
 
 (bv) Color.—The color shall be “water white,’ that is, not darker than 
 No. 21 Saybolt Chromometer. 
 
 (c) Flash Point.—The flash point shall not be lower than 86° F. (30° C.) 
 when tested in the Tag closed tester. 
 
 (d) Blackening.—It shall not blacken or corrode clean metallic copper 
 in 30 min. at the boiling point of the spirits. 
 
 (e) Distillation.—The distillate below 266° F. (130° C.) shall not exceed 
 5 per cent. 
 
 The distillate below 446° F. (230° C.) shall not be less than 97 per cent. 
 
 (f) Acidity.—The residue after distillation shall be neutral. 
 
 II. METHODS OF TEST 
 
 3. The properties enumerated in these specifications shall be determined 
 in accordance with the following methods of test: 
 
 (a) Color—The test for color shall be in accordance with the Tentative 
 Method of Test for Color of Refined Petroleum Oil by Means of the Saybolt 
 Chromometer (Serial Designation: D 156—23 T) of the American Society for 
 Testing Materials.* : 
 
 A fresh aqueous solution of potassium dichromate in distilled water, 
 containing 0.0048 g. KyCr.O7 per liter, is approximately equivalent to No. 21 
 Saybolt Chromometer. 
 
 (0b) Flash Point.—The test shall be made in accordance with the Standard 
 Method of Test for Flash Point of Volatile Flammable Liquids (Serial Desig- 
 nation: D 56) of the American Society for Testing Materials.+ 
 
 Blackening—A clean strip of mechanically polished pure Sheet copper, 
 about 14% in. (1.8 cm.) in width and 3 in. (7.5 em.) in length, shall be placed 
 in a glass test tube about 34 in. (1.9 em.) in width and 18 in. (46 cm.) in 
 length. Sufficient of the sample to be tested shall be added to completely 
 cover the strip and heated rapidly to boiling. It is most convenient to heat 
 higher than the initial boiling point of the mineral spirits. The sample shall 
 
 * Proceedings, Am. Soc. Testing Mats., Vol. 23, Part I, p. 682 (19238) ; also 
 1925 Book of A. S. T. M. Tentative Standards, p. 374. 
 + 1924 Book of A.S.T.M. Standards. 
 
Turpentine and Mineral Spirits 565 
 
 the tube by immersion in an oil bath maintained at a temperature slightly 
 be kept boiling for 30 minutes without any actual distillation taking place 
 and the copper strip then examined for blackening. <A slight tarnish shall 
 be disregarded, but any marked blackening shall be cause for rejection. 
 
 Distillation—The test shall be in accordance wth the Tentative Method 
 of Test for Distillation of Gasoline, Naphtha, Kerosine and Similar Petroleum 
 Products (Serial Designation D 86 — 26 T) of the American Society for 
 Testing Materials.* 
 
 Acidity—The cooled residue from the distillation flask shall be collected 
 in a test tube, three volumes of distilled water added, and the tube thoroughly 
 shaken. The mixture shall be allowed to separate and the aqueous layer 
 removed to a clean test tube by means of a pipette. One drop of a 1-per-cent 
 solution of methyl orange shall be added. No pink or red color should be 
 formed. 
 
 A. 8. T. M. STANDARD METHOD OF TEST FOR FLASH POINT 
 OF VOLATILE FLAMMABLE LIQUIDS 
 
 1. (a) The Tag Closed Tester shall be used for all volatile flammable 
 liquids flashing below 175° F. with the exception of products classed as Fuel 
 Oil. Determination of the flash point of fuel oil by the Tag Tester is permis- 
 Sible, but the Pensky-Martens Tester is to be preferred. aa | 
 
 (b) The Tag Closed Tester shall conform to the following dimensions 
 within the limits of tolerances given: : 
 
 DIMENSION. NORMAL, TOLERANCE. 
 Depth of water surface below top of 
 ae ob eek eee cess 13g5 (27.8mm.) +1, (0.4 mm.) 
 Depth of oil surface below top of cup, 
 Sy eee’ esis acne ees 1545 (294mm.) +i%, (04mm.) 
 
 Depth of top of bulb of oil thermom- 
 eter when in place below top of 
 
 RN MR oo ss Ce ccc a ule co eee 1%, (38.3 mm.) +4 (0.8 mm.) 
 Inside diameter of oil cup at top, in 2% (54.00mm.) +0.005 (0.1 mm.) 
 Remeemreer On CUD, 2. .... 0... cee e. 68 pe eat 
 Diameter of bead on top of cover, in 54, (4.0mm.) +14, (0.4 mm.) 
 
 The plane of underside of cover to be between the top and bottom of 
 . the burner tip when the latter is fully depressed. 
 
 (c) The thermometer shall conform to the following requirements. 
 These specifications cover a special thermometer graduated in either Centi- 
 grade or Fahrenheit degrees as specified, the ranges being —7 to +110° C. 
 or +20 to +230° F., respectively. 
 Type: Etched stem, glass. 
 
 Ligui: Mercury 
 RANGE AND SUBDIVISION’: —7 to 110 Ce in 0.59 ©) or. 20: f0> 230 in 
 
 1 
 ToraL LENGTH: 273 to 277 mm. (10.75 to 10,92 in.). 
 
 SteM: Plain front, enamel back, suitable thermometer tubing. Diameter, 
 6.0 to 7.0 mm. (0.24 to 0.28 in.). 
 
 * Proceedings, Am. Soc. Testing Mats., Vol. 26; Part I. (1926): also 1926 
 Book of A. S. T. M. Tentative Standards, are 
 
566 Turpentine and Mineral Spirits 
 
 Bus: Corning normal or equally suitable thermometric glass. 
 Length, 9 to 18 mm. (0.35 to 0.51 in.). 
 Diameter, not greater than stem. . 
 
 DISTANCE TO —7° C. oF +20° F. Line From Borrom oF BULB: 75 to 90 mm. 
 (2.93 to 3.54 in.). 
 
 DISTANCE TO 110° C. OR 930° KF, LIne FROM TOP OF THERMOMETER: 25 to 40 
 mm. (0.98 to 1.57 in.). 
 
 EXPANSION CHAMBER: TO permit heating the thermometer at least 50° C. 
 (90° F.) above highest temperature on scale. 
 
 FILLING ABOVE MERCURY : Nitrogen gas. 
 
 Top FrinisH: Glass ring. 
 
 GrapuATION: All lines, figures, and letters clear cut and distinct. The whole 
 degree Centigrade lines or the first and each succeeding 5° F. line to be 
 longer than the remaining lines. Graduations to be numbered at each 
 multiple of 5° C. or 10° F. 
 
 IMMERSION: 57 mm. or 2% in. The words “S7-mm. immersion” on Centi- 
 grade or “2%4-in. immersion” on Fahrenheit thermometers and a line 
 around the stem 57.0 mm. or 925 in. above the bottom of the bulb shall 
 be etched on the thermometer. 
 
 SPECIAL MARKETING :* “A.S.T.M. P.M. and Tag,” a serial number and the manu- 
 
 facturer’s name or trade mark shall be etched on the stem. 
 
 ScaLE Error: The error at any point of the scale when the thermometer is 
 standardized as provided below shall not exceed 0.5° C. or 1° F., respec- 
 tively. 
 
 STANDARDIZATION : The thermometer shall be standardized at the ice point 
 and at intervals of approximately 20° CG. or 50° F. for 57-mm. or 2%-in. 
 immersion and for the following temperatures of the emergent mercury 
 
 eolumn : 
 AVERAGE TEMPERATURE OF EMERGENT 
 THERMOMETER READING Mercury COLUMN 
 Pe Views Bs 70° F. 2c. 70° FB. 
 40° GC. 100° F. 31°: C.. ©3867 
 TO: C. .150S 40°C. 104° F. 
 100° C, 212° F. 48°C. 118° F. 
 
 Case: The thermometer shall be supplied in a suitable case on which shall 
 appear the marking: ‘A S.T.M. P.M. and Tag., —7T to +110° CO.” oE 
 “A STM. P.M. and Tag., +20 to +230° F.” according to the type of 
 thermometer. 
 
 Nore.—For the purpose of interpreting these specifications the following 
 definitions apply: 
 
 The total length is the over-all length of the finished instrument. 
 
 The diameter is that measured with a ring gage. 
 
 The length of the bulb is the distance from the bottom of the bulb to the 
 beginning of the enamel backing. 
 
 The top of the thermometer is the top of the finished instrument. 
 
 2. (a) If gas is available, connect a \%-in. rubber tube to the corrugated 
 gas connection on the oil cup cover. If no gas is available, unscrew the 
 
 * This thermometer is identical with the low-range instrument specified for 
 use with the A. S. T. M. Pensky-Martens Closed Tester. 
 
 at) ‘ 
 ee oe 
 
 ae 
 
Turpentine and Mineral Spirits 567 
 sl Rita 
 
 test flame burner-tip from the oil chamber on the cover, and insert a wick 
 of cotton cord in the burner-tip and replace it. Put a small quantity of 
 cotton waste in the oil chamber, and insert a small quantity of signal, sperm 
 or lard oil in the chamber, light the wick and adjust the flame, so that it is 
 exactly the size of the small white bead mounted on the top of the tester. 
 
 (b) The test shall be‘performed in a dim light so as to see the flash 
 plainly. 
 
 (c) Surround the tester on three sides with an inclosure to keep away 
 draughts. 
 
 A shield about 18 in. square and 2 ft. high, opens in front, is satisfactory, 
 but any safe precaution against all possible room draughts is acceptable. 
 
 Tests made in a laboratory hood or near ventilators will give unreliable 
 results. 
 
 (dq) See that the tester sets firm and level. 
 
 (e) For accuracy, the flash-point thermometers which are especially 
 designed for the instrument should be used, as the position of the bulb of 
 the thermometer in the oil cup is essential. 
 
 3. Put the water-bath thermometer in place, and place a receptacle under 
 the overflow spout to catch the overflow. Fill the water bath with water 
 at such a temperature that, when testing is started, the temperature of the 
 water bath will be at least 20° F. (11° C.) below the probable flash point 
 of the oil to be tested. . 
 
 4. Put the oil cup in place in the water bath. Measure 50 cc. of the 
 oil to be tested in a pipette or a graduate, and place in the oil cup. The 
 temperature of the oil shall be at least 20° F, (11° C.) below its probable 
 flash point when testing is started. Destroy any bubbles on the surface 
 of the oil. Put on the cover, with flash-point thermometer in place and gas 
 tube attached. Light the pilot light on the cover and adjust the flame to 
 the size of the small white bead on the cover. 
 
 5. Light and place the heating lamp, filled with alcohol, in the base of 
 the tester and see that it is centrally located. Adjust the flame of the 
 alcohol lamp so that the temperature of the oil in the cup rises at the rate 
 of about 1.8° F. (1° C.) per minute, not faster than 2° F. (1.1° C.) nor 
 slower than 1.6° F. (0.9° C.) per minute. 
 
 6. (@) Record the barometric pressure which, in the absence of a lab- 
 oratory instrument, may be obtained from the nearest Weather Bureau 
 Station. 
 
 (b) Record the temperature of the oil sample at start. 
 
 (c) When the temperature of the oil reaches 9° F. (5° ©.) below the 
 probable flash point of the oil, turn the knob on the cover so as to introduce 
 the test flame into the cup, and turn it promptly back again. Do not let it 
 snap back. The time consumed in turning the knob down and back should 
 be about one full second, or the time required to pronounce distinctly the 
 words “one-thousand-and-one.” 
 
 (d) Reeord the time of making the first introduction of the test flame. 
 
 (e) Record the temperature of the oil Sample at the time of first test. 
 
 (f) Repeat the application of the test flame at every 1° F. (0.5° C.) rise 
 in temperature of the oil until there is a flash of the oil within the cup. 
 
 Do not be misled by an enlargement of the test flame or halo around it 
 when entered into the cup, or by slight flickering of the flame; the true 
 
568 Turpentine and Mineral Spirits 
 
 flash consumes the gas in the top of the cup and causes a very slight 
 explosion. 
 
 (g) Record the time at which the flash point is reached. 
 
 (h) Reeord the flash point. 
 
 (i) If the rise in temperature of the oil, from the “time of making the 
 first introduction of the test flame” to the “time at which the flash point 
 is reached” was faster than 2° F, (1.1° C.) or slower than 1.6° F. (0.9° ©.) 
 per minute, the test should be questioned, and the alcohol heating lamp 
 adjusted so as to correct the rate of heating. It will be found that the wick 
 of this lamp can be so accurately adjusted as to give a uniform rate of rise 
 in temperature within the above limits and remain So. 
 
 7. (a) It is not necessary to turn off the test flame with the small regu- 
 lating valve on the cover; leave it adjusted to give the proper size of flame. 
 
 (vb) Having completed the preliminary test, remove the heating lamp, 
 lift up the oil cup cover, and wipe off the thermometer bulb. Lift out the 
 oil cup, and empty and carefully wipe it. Throw away all oil samples after 
 once used in making a test. 
 
 (c) Pour cold water into the water bath, allowing it to overflow into a 
 receptacle, until the temperature of the water in the bath is lowered to 15° 
 F. (8° C.) below the flash point of the oil, as shown by the previous test. 
 
 With cold water of nearly constant temperature, it will be found that a 
 uniform amount will be required to reduce the temperature of the water bath 
 to the required point. 
 
 (ad) Place the oil cup back in the bath and measure into it a 50-ce. charge 
 of fresh oil. Destroy any bubbles on the surface of the oil, put on the cover 
 with its thermometer, put in the heating lamp, record the temperature of 
 the oil, and proceed to repeat the test as described above in Sections 4 to 6, 
 inclusive. Introduce the test flame for first time at a temperautre of 10° F. 
 (5.5° ©.) below the flash point obtained on the previous test. 
 
 8. If two or more determinations agree within 1° F. (0.5° C.), the average 
 of these results, corrected for barometric pressure, shall be considered the 
 flash point. If two determinations do not check within 1° F. (0.5° C.), a 
 third determination shall be made and, if the maximum variation of the 
 three tests is not greater than 2° F. (1° C.), their average, after correcting 
 for barometric pressure, shall be considered the flash point. 
 
 9. Correction for barometric pressure shall only be made in cases of dis- 
 pute or when the barometer reading varies more than % in. (13 mm.) 
 from the standard pressure of 29.92 in. (760 mm.). When the barometer 
 reading is below this standard pressure, add to the thermometer reading 
 1.6° F. (0.9° C.) for each inch (25 mm.) of barometer difference to obtain 
 the true flash point. When the barometer reading is above the standard 
 pressure, deduct 1.6° F. (0.9° C.) for each inch (25 mm.) of barometer 
 difference to obtain the true flash point. 
 
 wh 
 
 pais ce Th ali onal ich 
 
CHAPTER XXXII 
 EXAMINATION OF FLAXSEED 
 
 Preparation of Sample.—Sample is quartered until 500 
 erams are obtained. In quartering, seed must be poured at 
 center of pile to evenly distribute seed and impurities. All 
 of the dirt which settles to the bottom must be carefully 
 brushed up and added to the pile. Screen the 500 gram sam- 
 ple through 10 mesh until about 50 grams remains on the 
 sereen. The residue is hand picked and everything other than 
 linseed is set aside and weighed with the dust. The clean seed 
 obtained at this picking is added to what has passed through 
 the 10 mesh screen. The seed is then passed through a 20- 
 mesh screen, rubbing the seed around in the screen so as to 
 remove any seed attached to it. The under size is collected and 
 weighed after the coarse pickings have been added to it. This 
 constitutes the first dust. The partially cleaned linseed is then 
 reduced to 50 grams in a rifflesampler. This is divided into 
 two 25-gram portions which are hand picked separately and 
 the impurities weighed separately. All linseed portion, 
 whether dried seed or broken seed, is to be put with the lin- 
 seed. After corrected calculation, the total impurities are 
 obtained. The impurities found in the second picking should 
 agree within 60 milligrams. 
 
 Oil in Flaxseed.—A 3-gram sample of the clean seed is 
 weighed out and is ground in an agate mortar with an equal 
 part of fine sea-sand which has been washed with hydrochloric 
 acid. The ground sample is placed in a Soxlet thimble and 
 extracted with redistilled ether for three hours. The distillate 
 is placed in a weighing dish and the ether is removed by 
 evaporation. The residue is then dried for one-half hour at 
 103° C., and the oil is weighed. 
 
 Oil in Oil Cake.—A 10-gram sample of undried oil cake is 
 placed in a Soxlet thimble and extracted in the same way as 
 described under Oil in Flaxseed. 
 
 Water in Oil Cake.—Weigh 5 grams of oil cake and place in 
 flask fitted with clean cork. Weigh flask, cork and contents ; 
 
570 Examination of Flaxseed 
 
 connect with hydrogen generator, and start flow of hydrogen 
 at the rate of 2 bubbles per second. Place flask in paraffin 
 bath at a temperature of 110° C., and heat in current of hydro- 
 gen for two hours. Disconnect tubing, and wipe clean of 
 paraffin while hot, with absorbent paper. Cool and draw dry 
 air through flask to remove hydrogen. Disconnect, replace 
 original cork, and weigh. Loss of weight reported as moisture. 
 
 Protein in Oil Cake.—Protein is found by determining total 
 nitrogen by the Kjeldahl method, calculating it to protein. 
 
 Coleman-Fellows Method for Oil Content.—Recent work 
 carried out by Coleman and Fellows of the U. 8. Department 
 of Ariculture has resulted in the publication of Bulletin 1471 
 on the Oil Content of Flaxseed, which presents a new method 
 for the rapid determination of the oil content. The paper 
 referred to also deals with the sources of variation in the oil 
 content and grading of the seed as to oil content. The sources 
 of variation are well known and include geographical origin, 
 such as Argentina, Canada, North Dakota, ete.; latitudinal 
 source within any particular country; total rainfall; and 
 regularity of rainfall. In general, Argentine seed contains 
 more oil than seed from any of the other places mentioned, but 
 poor Argentine seed may contain less than good North Dakota 
 seed. In addition to grading seed as to its source the follow- 
 ing criteria are, or have been, used or suggested, weight per 
 bushel, moisture content, soundness of seed, dockage, color 
 and size of seed, and numerical grading which is the compo- 
 site of all the above factors. None of the above methods of 
 grading has been found to give dependable information as to 
 the per cent of oil in flaxseed. 
 
 Wesson observed that the change in the refractive index 
 of halowax and cottonseed oil mixtures was directly propor- 
 tional to the per cent of oil present. The authors of Bulletin 
 1471 observed the same relationship in halowax-linseed oil 
 mixtures. The refractive index of halowax used in the investi- 
 gation was 1.63354@25° C. and of the linseed oil, 1.47878 @29° 
 C. The decrease in the refractive indice of halowax in mix- 
 tures of the two was 0.001906 for each per cent of linseed oil 
 present. 
 
 Directions for Preparation of Conversion Tables—(1) Into 
 three 4 ounce bottles, previously weighed, place approximately 
 25 cubic centimeters of halowax oil and note the exact weight 
 
 «Tal 
 
Examination of Flaxseed 571 
 
 sa nEEnEEEEEEEEEEEEREE ae 
 
 of the halowax oil added to each bottle. Next add linseed oil 
 to each of the three bottles so that, by weight, a 10, a 12, and 
 a 14 per cent solution of linseed oil in halowax oil will be ob- 
 tained. Additional mixtures may be made if desired, but three 
 will usually be enough. It is not necessary to obtain even per- 
 centages of linseed oil in the mixture. As the optical method 
 is standardized against the ether-extraction method, linseed 
 oil obtained by ether extraction is used for making up the mix- 
 tures with halowax oil. 
 
 When the bottles containing the known percentages of lin- 
 seed oil have been thoroughly mixed, read the refractive in- 
 dex of each mixture, as well as the refractive index of the 
 halowax oil used, at a temperature of 25° C., and from these 
 data determine the change in the refractive index of the halo- 
 wax oil per 1 per cent of linseed oil present in the mixture. 
 The results will be of the order of 0.001906. The constant ob- 
 tained will depend upon the original refractive indices of the 
 halowax oil and the linseed oil used. 
 
 (2) Determine the percentage by weight of linseed oil pres- 
 ent in halowax oil when 4 cubic centimeters of halowax oil are 
 mixed with a 2-gram sample of ground flaxseed. To do this 
 the weight of 4 cubic centimeters of halowax oil must first be 
 determined. This is accomplished by direct weighing of sev- 
 eral 4 cubic centimeter portions of halowax oil or by determin- 
 ing the specific gravity of the halowax oil and by multiplying 
 this value by 4, the volume of halowax oil used in the test. 
 
 Knowing the exact weight of the 4 cubic centimeters of halo- 
 wax oil and the weight of linseed oil that would be present in 
 flaxseed of known composition, the percentage of linseed oil 
 in the halowax-linseed oil mixture when 2 grams of ground 
 flaxseed are used in the test is now determined. To illustrate, 
 suppose a sample of flaxseed contained 31 per cent of linseed 
 oil. A 2-gram sample would contain 0.62 gram of oil. If this 
 0.62 gram of oil was mixed with 4 cubic centimeters of halowax 
 oil which weighed 4.904 grams, the percentage of linseed oil 
 in halowax oil would be 11.224 per cent. Conversions of this 
 nature are then made over any part of the scale from 3 to 49 
 per cent as is illustrated in Table 69 in whole per cents and 
 tenths of 1 per cent, depending on how extensive a table is 
 desired. Ag an aid in‘ preparing this step in the conversion 
 table the following formula will prove useful: 
 
 Weight of oil in 2-gram sample of flaxseed Percentage 
 
 Weight of 4 cubic centimeters of halowax oil—of linseed 
 
 + weight of oil in 2-gram sample of flax- oil in the 
 seed mixture 
 
572 Examination of Flaxseed 
 
 TABLE 69 
 Percentages of iinseed oil in a halowax-linseed oil mixture made by adding 
 4 cubie centimeters (4.904 grams) of halowax oil to 2 grams of ground flax- 
 seed containing 31, 31.1, 31.3, 31.5, 31.7, and 32 per cent of linseed oil. 
 
 Percentage 
 Percentage of linseed oil 
 of linseed oil in the halo- 
 in flaxseed wax-linseed 
 sample oil mixture 
 31.0 11.224 
 od 11.256 
 31.3 11.320 
 31.5 11.384 
 ak Bg 11.448 
 32.0 11.544 
 
 (3) In the case of the experiments, the change in refractive 
 index per each per cent of linseed oil present was 0.001906. 
 All that is necessary, therefore, to express refractive index 
 values in terms of the percentage of linseed oil present in 
 ground flaxseed is to multiply each per cent and tenth of 1 per 
 cent of linseed oil, as described in section 2 above, by the con- 
 stant described under section 1. Finally, point off nine deci- 
 mal places and subtract the value obtained from the refrac- 
 tive index of the halowax oil used in the tests. The results 
 will appear like those in Table 70, which is the section of the 
 scale usually used for flaxseed. 
 
 (4) As is general with optical measurements, the tempera- 
 ture at which the readings are made is important. It is neces- 
 sary when using this method to adjust individual readings to 
 the same temperature basis. For general conditions 25° C. 
 has been selected as an average laboratory temperature. Thus, 
 for every degree above or below 25° C., 0.00045 is added to or 
 subtracted from the original reading. This adjustment can 
 not be overlooked, as this reading—0.00045—is equivalent to 
 approximately 0.75 per cent of oil. 
 
 _ Details of Method for Making Test.—(1) Grind 25 grams 
 of the flaxseed sample so that at least 80 per cent of the meal 
 will pass through a 34-grits gauze sieve. 
 
 (2) Weigh out 2 grams of the ground sample and empty 
 it into a 3-inch porcelain mortar, which has been previously 
 heated to 70° C., and grind the flaxseed meal with 4 cubic 
 centimeters of halowax coal grade No. 1007, for se least two 
 minutes. 
 
 (3) Filter through a small folded filter, using a 40- milli- 
 meter glass funnel seated on a flat- bottomed test tube. 
 (4) Let the tube and contents cool to room temperature. 
 
 ‘ 
 ‘s 
 9 
 ; 
 
 . 
 
 . 
 
 - 
 i 
 °S 
 Rs 
 % 
 2 
 sae 
 
 » 
 a 
 Bi 
 
Examination of Flaxseed S75 
 
 Place a drop of this mixture on the prism of the refractometer 
 and take the average of three readings. 
 
 (5) Note the temperature, and for every degree above 25° 
 C. add 0.00045 to the refractometer reading and for every de- 
 gree below 25° C. subtract this amount. 
 
 TABLE 70 
 
 For converting refractometer reading into percentages of linseed oil. 
 (Readings made at 25° C.) 
 Linseed oil 
 
 Refractometer reading Per cent 
 to lag ein ay ng kbd tans Ge cb ww sens ee ee e's 35.1 
 ee Gee ics alc. Se <.disvs- dese bo ee ba Seine de hase ase poe 
 ESS ASO a on ar a 35.3 
 TOR RI laa lacs ook sss, visi cise sees ees tienecscensess 35.4 
 Tete CNRS foe 6 core 5a 5 ods we wah 6 ass s’a sees vs eie sees 35.5 
 TE te 7s 5 oe gd sls ads cy he seine s ket psececales 35.6 
 Ee Pe Ss iole 3 Gino aise sss « « vise vcd-a sw ov seen ese aaens 35.7 
 oat ae fe his ede ins’ o's odo ¥ % ace, 9 ¢ 0.08 disco ote ee eases 35.8 
 Beeline ann cael als neo 3)s wee se-eiels"esale ad ee tye od wv b wie’ 35.9 
 NM Ra gia sles Sov isig c's «sds lee cele pesbedeedees come’ 36.0 
 Sah iw 5 Sa ss ce vos ole a doe Oa eh iy vale ae aloses 36.1 
 
 (6) Wipe off the prism of the refractometer with a piece 
 of soft absorbent cotton. 
 
 (7) Note the percentage of oil in the sample under test by 
 comparing the refractometer reading with a set of oil values 
 which have been assigned to the refractometer readings. 7 
 
 A study of 120 seed samples* by both the A. O. A. C. ether 
 extraction and the optical methods shows that the results 
 of 45.8 per cent of the samples tested by the optical method 
 varied less than 0.1 per cent from the results secured by the 
 method of the Association of Official Agricultural Chemists; 
 39 per cent of the results varied 0.1 to 0.19 per cent; 14.2 per 
 cent varied 0.2 to 0.29; and only 5 per cent varied 0.3 per cent 
 or more, the greatest variation in any sample being only 0.33 
 per cent. 
 
 The method works equally well on linseed cake or meal. 
 With the linseed cake it was necessary to pass the material 
 through a burr mill in order to grind it to a fine state of sub- 
 division. For sake of uniformity the linseed meal was also 
 passed through a burr mill. 
 
 SPECIAL Points FOR CONSIDERATION IN MAKING THE 
 
 Optical TEst. 
 
 Fineness of Division of Sample.—As the method was being 
 developed it was brought out that the seed had to be pulver- 
 
 *Details given in Bulletin 1471. 
 
574 Examination of Flaxseed 
 
 ized to a very fine state of subdivision before accurate results 
 were obtainable. It was found that seed ground on an attrition 
 mill was not in a satisfactory condition as it was too coarse 
 for rapid and complete solvent action. Many trials were made 
 with grinding devices of various kinds, and it was finally de- 
 termined that a small flouring mill, having rolls 6 by 6 inches, 
 corrugated 40 to the inch, was the most satisfactory device for 
 grinding flaxseed samples for analytical work. Such a mill 
 reduces and pulverizes flaxseed without difficulty, to a point 
 where over 80 per cent will pass through a 34 grits gauze in 
 about four to five minutes. 
 
 Volume of Halowax Oil to Use-——Experiments have shown 
 that 4 cubic centimeters of halowax oil.is the optimum quan- 
 tity to use with a 2-gram sample of flaxseed meal. With this 
 quantity of solvent this method checks the ether-extraction 
 method the closest. Although 3 cubic centimeters work well 
 with some samples, with the majority this quantity is usually 
 completely absorbed by the meal necessary for the test. 
 
 Temperature at Which Readings Are Made.—The tempera- 
 ture at which readings are made should always be the same in 
 order that different operators may obtain concordant results. 
 This end can be accomplished by using a conversion chart or 
 by the continued use of a temperature regulator. It is be- 
 lieved the chart system is preferable, inasmuch as less time is 
 lost in making intial tests, because the operator does not have 
 to wait until a specified temperature is reached. 
 
 Temperature of Extraction.—The optimum temperature at 
 which to allow the extraction to take place appears to be 70° 
 C. Extracting in the cold reduces the percentage of oil ex- 
 tracted. 
 
 Filtering the Halowax-Linseed Oil Mixture —The filtering 
 of the halowax-linseed oil Mixture is accomplished by the use of 
 a small dry, folded filter, instead of the absorbent-cotton filter 
 recommended by Wesson. By using the small folded filter, a 
 cleaner filtrate is obtained and with less effort than when 
 using absorbent-cotton filter. Only a few drops of the filtrate 
 are necessary for making the refractometer reading. 
 
 Cleaning Prism; Warning.—Because of the highly solvent 
 action of the halowax oil, it is absolutely essential for accurate 
 results that this material be completely removed from the 
 faces of the prism after each test has been completed. Failure 
 to do this will not only result in an incorrect oil test reading, 
 
 but will also eventually result in a corrosive action on the back — 
 
 of the prism. 
 
 i Sic: 
 
CHAPTER XXXIII 
 
 EXAMINATION OF WAXES AND POLISHES 
 
 The principal use of waxes in the paint and varnish in- 
 dustry is in polishes for use on automobiles and floors. The 
 waxes which predominate are beeswax and carnauba. These 
 waxes consist chiefly of esters of cerotic acid (C,;H;,COOH) 
 or of homologous acids and myricyl (C;.H«,OH) alcohol. The 
 fatty acids of the oils and fats are not present. Both bees- 
 wax and carnauba wax contain some hydrocarbons, the former 
 12.5 to 14.5 per cent and the latter less than 2 per cent. 
 
 BrEswax * 
 
 Refractive Index.—The refractive index of beeswax lies be- 
 tween 1.4398 and 1.4451 at 75°, at which temperature pure 
 beeswax is clear. For each degree above or below 75° C. 
 0.00037 should be added or subtracted. 
 
 Specific Gravity.—The specific gravity of beeswax may be 
 determined by the following method. After eliminating all 
 air bubbles by careful melting and then allowing to cool for 
 2 to 24 hours, the sample is weighed in air and then in alcohol. 
 The specific gravity is then calculated from the formula 
 Weight in air 
 
 a ee 
 Loss in aleohol X sp. gr. of alcohol 
 
 The specific gravity for pure beeswax lies between 0.961 and 
 0.968 at 15.5°/15.5°. 
 
 Melting Point.—The melting point of beeswax is determined 
 by the capillary tube method, and averages about 60° C. 
 
 Acid Number and Saponification Number.—Place 5 grams 
 of the wax in a 200 ec. Erlenmeyer flask with about 25 ce. 
 neutral aleohol and heat on the water bath until the mixture 
 is entirely melted. Then add 1 ce. of phenolphthalein solu- 
 tion and titrate the free acids quickly with N/2 alcoholic 
 potash. Add 50 ec. more of the N/2 potash and heat the 
 mixture for at least 3 hours over a direct flame with a 
 
 *Much information presented in this chapter has been obtained from the 
 following references: lL. Feldstein, U. S. Bur. of Chem. Cire. 86 (1911); F. 
 Utz, Farben Ztg. 29, 645 (1924); Kebler & Boyles, U. 8S. Bur. of Chem. Bull. 
 150 (1912) ; P. Bourcet, Bull. Soc. Chem. 39, 421 (1924). 
 
576 Examination of Waxes and Polishes 
 
 reflux condenser. The excess of potash is determined with 
 N/2 HCl. <A blank on the KOH should be run. The acid 
 values range from 16.8-20.6, the saponification values from 
 88-96. The ester value is the difference between the saponifi- 
 cation value and the acid value. The ratio of the ester value 
 to the acid value for pure beeswax ranges from 3.5 to 4. 
 
 Detection of Stearic Acid.—Boil 1 gram of the wax for sev- 
 eral minutes with 15 cc. of 80 per cent alcohol. Allow to cool 
 
 to 18-20°. Filter into a 200 ec. cylinder and dilute filtrate with 
 water to about 200 ce. If stearic acid is present, it separates 
 into flakes and collects at the surface. The test is sensitive to 
 1 per cent. If from 7 to 8 per cent are present, a thick, 
 creamy mixture results. 
 
 Detection of Resins —The following alternate methods may 
 be used for determination of resins. 
 
 (a) A mixture of 5 grams of the wax and 20 to 25 ce, 
 HNO, (1.32 to 1.33), is kept at the boiling point for about 1 
 minute. Dilute with an equal volume of water, and render 
 slightly alkaline with NH,OH. The solution decanted from the 
 separated wax, in the absence of resin, is of a yellowinsh 
 color, while the presence of resin produces a more or less 
 intense reddish brown coloration. 
 
 (b) Heat 1 gram of the wax for a few minutes with 25 ce. 
 or 50 per cent alcohol (this strength will not extract stearic 
 acid if present). Cool and filter. Evaporate the filtrate to 
 dryness on a steam bath, and add 5 ee. acetic anhydride. Heat 
 to boiling. Cool and then carefully allow H.SO, (1.53) to 
 flow into the solution. The presence of the minutest quantity 
 of resin will develop a fine violet (fugitive) color. 
 
 Detection of Paraffin—The following method is the only 
 one by which paraffin can be detected with certainty. Melt 
 from 2 to 5 grams of the wax in a porcelain dish, then add an 
 equal weight of finely powdered KOH. Continue heating for 
 a few minutes, with thorough stirring. Cool and powder the 
 hard mass. Mix the resulting powder with three times as 
 much potash lime as wax used. Then introduce this mixture 
 into a thick walled tube, immerse in an oil bath; heat to 250° 
 C. for 2 to 4 hours. After cooling, powder the tube with 
 its contents. Place the mass in a Soxhlet apparatus and ex- 
 tract with petroleum ether for several hours. The petroleum 
 ether is evaporated, and the residue dried at 100° C. and 
 
Examination of Waxes and Polishes Sf 
 
 weighed. By this treatment, the esters are converted into 
 aleohols, and these alcohols on heating with potash lime are 
 in turn converted into their respective acids, while the hydro- 
 carbons present are not affected and are extracted with the 
 petroleum ether. Pure beeswax contains from 12.5 to 14 per 
 cent hydrocarbons, and any adulteration with paraffin or 
 allied bodies will increase this percentage. 
 
 Detection of Glycerin.—2 to 3 grams are heated in a large 
 test tube on the water bath with 10 to 15 ce. KOH for 1 hour. 
 15 ce. of water saturated with H.SO, are then added and the 
 solution filtered. 2 cc. of this filtrate are then mixed with 20 
 ec. of saturated bromine water, and heated 20 minutes on the 
 water bath. The bromine is removed by boiling. 2 ce. are 
 then put in a test tube with 0.1 cc. of a 1:20 solution of codeine 
 in alcohol and 5 ce. of concentrated H.SO,, and heated 2 
 minutes on the water bath. If glycerol is present, a beautiful 
 bluish-green color appears, and this indicates the adition of 
 an animal or vegetable glyceride. The method indicates as 
 low as one per cent of glycerides. 
 
 CaRNAUBA Wax 
 
 Carnauba wax is used very widely in place of and in com- 
 bination with beeswax in various preparations. The tests 
 usually made to determine the purity of carnauba wax are 
 Specific Gravity, which should be between 0.995 and 0.999 
 and Melting Point, which should be between 83°-91°. The 
 acid number, saponification number, etc. may also be run in 
 the same manner as for beeswax. There is given below a 
 chart showing the constituents of some of the more promi- 
 nent types of waxes. 
 
 TABLE 71 
 Spec.Grav. Melting Acid Saponification Iodine Refractive 
 15.5/15.5° Point °C. Value Value Value Index 
 Beeswax ..... 0.961-0.968 60- 16.8-20.6 88-96 8.8-10.7 1.4398 
 -1.4451 
 Ce TH 2G, 
 Candelilla .... 0.969-0.993 65-68 VG: 46-65 14.0-36.8 1.454 
 Carnauba .... 0.995-0.999 65-69 4-8 79-84 138.5 Ate 
 de 76-92 73 74 16. 
 Spermaceti ... 0.905-0.960 41-46 0.5-2.8 126-135 22:6 
 
 FinisHED Wax Propvucts 
 
 The tests that should be made on wax products such as 
 automobile polishes, shoe polishes, etc., to determine the con- 
 
578 Examination of Waxes and Polishes 
 
 stituents should include volatile matter. This determination 
 is carried out in the following manner. A small stoppered 
 weighing bottle containing 2-3 grams of the material is 
 weighed. 1-1.5 grams of the contents are quickly transferred 
 to a previously weighed 3-inch friction top can plug and the 
 bottle again weighed. The difference is the weight of the 
 polish. The lid and its contents are then heated for 3 hours 
 at 115°-120° C. cooled and weighed, the percentage non-volatile 
 is calculated from the residue in the dish and the weight of 
 material taken. The character of the volatile solvent em- 
 ployed should be determined. These solvents are usually 
 turpentine, mineral spirits or similar materials. The non- 
 volatile wax portion may be used for a determination of melt- 
 ing point or for other tests such as those outlined above. The 
 product should also be subjected to a practical test upon the 
 kind of surface on which it is to be employed in order to 
 determine its suitability in this direction. 
 
 Sa a 
 
CHAPTER XXXIV 
 
 TESTING RAW MATERIALS USED IN LACQUER 
 MANUFACTURE 
 
 The tests usually applied to nitrocellulose are Viscosity, 
 Color, and Stability. These are outlined below. There are 
 also included some tentative methods of examining solvents, 
 diluents, and pigments proposed for lacquer use. 
 
 Viscosity of Nitro-Cellulose.*—The viscosity of a nitro-cellu- 
 lose solution is measured in many different ways and there 
 are several standard units of measurement, such as seconds, 
 poises, bubbles, torque, ete. The method used by nitrocellu- 
 
 INSIDE OIA. 
 
 10.% DIA, BALL BEARING 
 (OIA. 0.793 T0.0.797CM 
 WEIGHT OF BALL 2.046h|4 
 
 TEMP OF SOLUTION 457i 
 
 THE APPARATUS FOR DETERMINING VISCOSITY 
 
 OF A SOLUTION BY THE FALLING BALL METHOD 
 
 CONSISTS OF A GLASS TUBE 14 INCHES LONG 
 
 HELD IN A VERTICAL POSITION BY A STAND AND 
 
 CLAMP. ON THE GLASS’ TUBE ARE TWO MARKS 
 
 2 INCHES FROM THE TOP AND BOTTOM AND 
 EXACTLY 10 INCHES APART 
 
 FIGURE 196 
 
 lose manufacturers and the one most commonly used in the 
 lacquer industry for the examination of nitrocellulose is the 
 falling ball method. This consists in measuring with a stop 
 watch the time required for a steel ball to fall through ten 
 inches of a solution in a one-inch-diameter vertical column 
 
 * Weisel method. 
 
580 Raw Materials Used in Lacquer 
 
 at a temperature of 25 degrees C. It is quite important that 
 the temperature be kept constant, as any variation in tempera- 
 ture will vary the viscosity, as will be noted by reference to 
 the curve showing the relation between viscosity and tempera- 
 ture. As 25 degrees C. is approximately room temperature 
 (77° F.) it is not difficult to prevent temperature change. For 
 determination of the viscosity of all types of nitrocellulose 
 except half-second types, the Hercules Powder Company has 
 adopted the following method: 
 
 Apparatus.—A 14-inch glass cylinder of one-inch inside 
 diameter having two marks 10 inches apart. One mark should 
 be two inches from the top of the cylinder and the other two 
 inches from its bottom. A standard 5/16 inch steel ball bear- 
 ing with diameter of 0.793 to 0.797 cm. and weighing between 
 2.046 and 2.054 grams. A Centigrade thermometer. <A cork 
 enclosed in tinfoil and a stop-watch. 
 
 Method.—The nitrocellulose is put into solution of the fol- 
 lowing formula: 
 
 Lbs. per __ Lbs. per 
 100 Lbs. Gallon 
 
 Nitrocellulose (Dry Weight)......... 12.2 0.94 
 Denatured Alcohol . .... 3.2 220) 1.69 
 Ethyl. Acetate 2.2 ..0.. ee Li 1.35 
 Benzol iv ee Pe ea eee 48.3 ould 
 
 100.0 7.69 
 
 After the Nitrocellulose is thoroughly dissolved, the solu- 
 tion should stand about one hour to permit bubbles to escape. 
 The sample is then brought to a temperature of 25° C. and the 
 glass cylinder is filled. The ball bearing igs then placed on 
 the surface of the sample in the cylinder and allowed to fall 
 through the solution. The cylinder should be held or sup- 
 
 ported in an exactly vertical position and the ball should be 2 
 
 dropped exactly in the center. The time required for the ball 
 to fall through the ten-inch column of solution is recorded in 
 seconds and reported as the viscosity of the Nitrocellulose. 
 
 Control Test for Half Second Types.—tIn the following 
 test, made for the purpose of determining the viscosity of half- 
 second types of nitrocellulose, a different formula is used for 
 the nitrocellulose solution. It is necessary to make a measure- 
 ment in a solution of higher viscosity and reduce the result 
 
Raw Materials Used in Lacquer 581 
 
 to terms of viscosity equivalent to the standard solution. 
 With very low viscosities the time interval is so small that 
 the determination is more or less of a guess, depending upon 
 the skill and personal equation of the operator. The appa- 
 ratus and method is the same as for other types except that 
 the nitrocellulose is put into a solution of the following for- 
 mula. 
 
 Half Second eect nee (dry weight)..... 20 % 
 I SS a ee ns 20 % 
 NE 2 ee 16% 
 er ee ke ee eka eee 44% 
 
 100 % 
 
 Although there are many factors which govern the viscosity 
 of a solution, such as temperature and solvent used, the prin- 
 cipal factor is the nitrocellulose itself. The viscosity of a 
 nitrocellulose is controlled by many conditions. The quality 
 of the linters resulting from the type of cotton, its maturity, 
 purification and degree of bleaching affect viscosity. 
 
 Different solvents give solutions of different viscosities 
 with the same nitrocellulose. In general the better the sol-. 
 vent the lower will be the viscosity. For example, acetone 
 will give a lower viscosity solution than ethyl or butyl acetate 
 for some types of nitrocellulose. Decreasing the proportion 
 of solvent to diluent usually increases the viscosity. Adding 
 diluent to a solution will increase the viscosity until the nitro- 
 cellulose is finally thrown out of the solution. The use of py- 
 ridine denatured alcohol in the manufacture of lacquers should 
 be avoided because the pyridine content is detrimental to the 
 solution on account of its drastic action in reducing the vis- 
 cosity. This viscosity reduction is caused by the rapid de 
 composition of the nitrocellulose. As there is no known 
 method of stopping this action, such will continue until the 
 nitrocellulose is disintegrated. 
 
 An increase in the concentration of a solution does not 
 necessarily give a proportionate increase in viscosity (as de- 
 termined by the falling ball method). As nitrocellulose is 
 added to a solution there is at first a very slight increase in 
 viscosity. As more nitrocellulose is added to the solution the 
 viscosity increases more rapidly in proportion to the nitro- 
 cellulose added. 
 
582 Raw Materials Used in Lacquer 
 
 Changes in temperature* very readily affect the viscosity 
 of a solution. The higher the temperature, the lower the vis- 
 cosity ; hence the necessity, when testing for viscosity, of keep- 
 ing the solution at a fixed temperature, which is standardized 
 at 25° C., as this is about normal room temperature, and most 
 convenient to maintain. 
 
 The following table shows how vara in temperature 
 affect viscosities. 
 
 VISCOSITIES OF 4, 20, 70, AND 140 SECOND NITRO-CELLULOSE 
 SOLUTIONS BETWEEN TEMPERATURE RANGE OF 10° C TO 40° C 
 
 VISCOSITIES 
 
 as 4 sec. 20 Sec. 70 Sec. 140 Sec. 
 40° C. 1.96 9.78 34.25 68.49 
 9 hea ON 2.48 12.42 43.46 86.92 
 30° C, 3.15 15.76 55.16 110.3 
 Zoe ha: 4.00 20.00 70.00 140.0 
 20° C, 5,08 25.38 ~~ 88.84 L773 
 153 0. 6.44 S221 112.8 odo 
 10° GC. 8.18 40.88 143.1 286.2 
 
 Stability and Durability of Nitro-Cellulose.—The stability 
 of nitrocellulose, or the property of resisting deterioration or 
 decomposition, is of great importance to users of nitrocellu- 
 lose. Stability in a nitrocellulose product is a property that 
 receives very careful consideration from many of the indus- 
 tries using nitrocellulose. Any treatment of the nitrocellulose 
 by users which would tend to decrease its stability should be 
 
 ——_ 
 
 strenuously avoided and the greatest care taken to secure from _ 
 
 manufacturers a properly stabilized nitrocellulose. The use 
 of pyridine denatured alcohol in the manufacture of lacquers 
 should be avoided because the pyridine content appreciably 
 affects the stability of the nitrocellulose. 
 
 One of the most reliable tests for determining the stability 
 of nitrocellulose is the 
 
 German or 135° C. Stability. Test—The method used to de- 
 termine whether nitrocellulose has the required degree of sta- 
 bility is that known as the German Stability Test, which is 
 sometimes referred to as the 135° C. Stability Test. The 
 necessary data to make this test are given below: 
 
 * See also “‘Some Observations on the Viscosity of Lacquers,” by C. D. Bogin 
 
 and C. W. Sims to appear in Jour. Ind. and Chem. End. early in 1928. 
 y Also % second nitrocellulose in a 20% solution. 
 
 ee ee ae 
 
Raw Materials Used in Lacquer 583 
 
 The bath used is of special design, built so that any desired 
 temperature can be maintained by means of a constant boiling 
 mixture. This bath can be obtained from Kimer & Amend, 
 New York City, who have the necessary data for making it 
 and who make them on order. An ordinary laboratory elec- 
 tric hot plate is used to heat the bath. 
 
 The glass tubes used in making the tests are 290 mm. long, 
 15 mm. inside diameter, and 17 mm. outside diameter. These 
 tubes are made from standard pyrex tubing having an exter- 
 nal diameter of 17-18 mm. and regular walls. The small vari- 
 ations in the regular stock tubing of the above specifications 
 
 K 15-STD Z COPPER TUBES SPACED 
 EENDS FINISHED AS SHOWN 
 ae ) 103 LONG 
 
 2x3 133 Brass PAD 
 
 or tad UNDER $!DE OF 
 
 S1D 3 BRASS UMOK 
 
 Ss 
 DRILL& TAP FOR peineoee eda 
 
 S10} coprer Pipe 
 : 3 STO FCOPPERPIP 
 : STOZ PIPE PLUG BRASS 
 
 ” ple-coppen SHEET THRUOUT +| i lh 
 —E—E— % 
 
 2 of 
 -|\so 
 
 CONSTRUCTION OF BATH FOR GERMAN (OR 135° C) 
 STABILITY TEST OF NITROCELLULOSE 
 
 FIGURE 197 
 
 do not affect the results. The tubes as made will project 6 
 or 7 mm. out of the bath, permitting ease in handling. The 
 solvent mixture used in the bath to maintain a temperature of 
 135° C. is approximately one part Xylol and four parts Toluol. 
 The exact mixture is found by ‘‘eut and try.’’ If the mixture 
 started with is too high more Toluol is added. If it is too 
 
584 Raw Materials Used in Lacquer 
 
 low, the condenser is allowed to run hot until the proper 
 temperature is reached. Because of the inflammable nature 
 of the solvents, care should be used not to allow any great 
 quantity to escape into the room without proper ventilation 
 and precautions. On continued operation the tendency is for 
 the temperature to rise, which is corrected by adding Toluol. 
 The temperature is read from a thermometer placed in a stop- 
 pered empty glass tube so that the bulb of the thermometer 
 
 OPEN ENO 
 
 ‘ 
 ok 
 
 BRAZE 
 
 STD. 2"BRASS PIPE CAP 
 
 STD. 2" BRASS PIPE— 
 
 WATER OUTLET SAME 
 AS WATER INLET 
 
 WATER INLET 
 by ‘ 
 STD, 4 BRASS PIPE a 
 
 ws STDZ BRASS UNION 
 
 Lee 
 
 ER OFF WITH FIL 
 og Pee 
 ' 
 
 | 
 
 TAP 
 
 STO. 2 BRASS PIPE— 
 
 | whe 
 
 STO. PIPE THO. FOR 2 BRASS 
 “UNION 
 
 CONDENSER FOR GERMAN HEAT TEST BATHE 
 FIGURE 198 
 
 occupies the same position as a sample of nitrocellulose. The 
 
 thermometer should read to tenths of a degree centigrade. 
 The methyl violet paper used is specially made so that the 
 
 eolor reactions are extremely sensitive to nitrous oxides. 
 
Raw Materials Used in Lacquer 585 
 
 They should be stored in a well stoppered bottle away from 
 any acid fumes. [Every new lot of papers received should be 
 checked against a standard to see whether they give the same 
 results as the previous lot received. 
 
 It is absolutely compulsory that a mask be worn protecting 
 the eyes and face whenever making this test. The mask should 
 be so made that a heavy sheet of clear cellulose acetate cellu- 
 loid is held in front of the face, thus protecting the eyes and 
 face from flying glass in case any unstable sample should flare 
 while being tested. While handling the tubes the hands should 
 be protected. This can easily be done by wearing heavy 
 eloves and using long pincers so that the hands are not over 
 the bath. The test is conducted in a room free from any acid 
 fumes whatsoever, preferably in a room by itself, but if this 
 is impossible then in some location where there will be no 
 damage from flying glass if a sample should flare. 
 
 The nitrocellulose is dried thoroughly, which is best accom- 
 plished by drying in an oven at 50° C. for fifteen hours. The 
 sample should be thoroughly dried, as the presence of alcohol 
 influences the test as well as lowers the weight of nitrocellu- 
 lose being tested. The weight of sample used is 2.5 grams, 
 which is shaken or pressed down in the tube so that it occupies 
 the lower two inches in the tube, making sure that no nitro- 
 cellulose adheres to the upper part of the tube. The methyl 
 violet papers are then suspended in the tube by hanging them 
 on a hook made on the end of a glass rod run through a cork 
 fitted in the top of the tube. This cork should be notched 
 along the side in order to take care of the expansion and con- 
 traction of air in the tube. The paper is so suspended that 
 its lower edge is one inch from the top of the nitrocellulose. 
 The bath is maintained at a temperature of 134.5° C+0.5° C. 
 After heating the sample for 10 minutes, the tube is inspected 
 at five-minute intervals. The determination is the time, in 
 multiples of five minutes, required for the methyl violet paper 
 to completely lose its violet color. An inspection of the methyl 
 violet paper is made by lifting the tube until the paper, but not 
 the nitrocellulose, is visible above the surface of the bath. 
 Properly purified nitrocellulose should stand a test of 20 min- 
 utes or more by this method. 
 
 In conducting this test it is extremely important to take 
 into consideration that dried nitrocellulose is very inflamma- 
 
586 Raw Materials Used in Lacquer 
 
 ble and that if it is ignited by fire, spark or static electricity 
 that the whole mass will flare very quickly. It is compulsory 
 that a mask be worn whenever making the test because if a 
 sample should flare during the test the glass tube will be shat- 
 tered and thrown to all parts of the room. Unless the face 
 is protected with a proper mask, the flying glass may seriously 
 injure the eyes and cut the face. 
 
 All stability tests are purely comparative and are used on 
 the basis that if a certain result is obtained, the material will 
 have certain properties based on past experience. If you 
 get twice the reading on one sample that you do on another, 
 it cannot be said that the higher one will last twice as long as 
 the other when exposed to destructive agencies unless past 
 comparisons have been made showing this. However, the 
 test is valuable in quickly saying whether the material is of 
 the required degree of stability. 
 
 Methyl Violet Papers.—The methyl violet papers used in 
 making the German Test for stability are made according to 
 the following procedure: 
 
 The dye solution used is made from the following formula: 
 
 Basic Rosaniline (converted to acetate) 0.2500 grams 
 
 Crystal Violet’ 2.0.4... . 55 0.1680 grams 
 C.. P. Glycerine. (2 =. 6 ce. 
 Distilled Water 2.2). Gt bil er 30 ee. 
 
 Knough of 95% ethyl aleohol is added to the above solution 
 to give 100 ce. of solution. 
 
 The rosaniline acetate used in the above is made by placing 
 0.2500 gram of basic rosaniline in a porcelain casserole, add- 
 ing an excess of glacial acetic acid and the casserole heated 
 on a steam bath until all the excess acid is removed. The 
 other ingredients are then added and the whole made up to 
 100 ce., using 95% ethyl aleohol. A small quantity of the solu- 
 tion is then placed in the deep angle of an inclined rectangu- 
 lar glass tray. A quarter sheet of S and S No. 597 filter paper 
 is then drawn through the solution and up over the side of 
 the dish to remove the surplus solution. The filter paper 
 used is an important factor in the results obtamed and it is 
 quite essential that the proposed paper be used. This opera- 
 tion should take 30 seconds. The strip should then be held 
 horizontally and gently waved to and fro so as to preclude 
 the possibility of the solution running or collecting in spots. 
 
Raw Materials Used in Lacquer 587 
 
 The alcohol dries rapidly, so that within a minute the strip 
 may safely be suspended vertically without danger of the 
 solution running. When air-dried the paper is ready to be 
 cut into strips 70 mm. long and 20 mm. wide. A hundred ce. 
 of the solution makes about 250 of the strips. These papers 
 should be made in a room free from any acid vapors whatso- 
 ever, especially nitric acid. It is claimed that this paper is 
 not affected by air, light, change of temperature, carbonic, 
 acetic, hydrochloric or sulphuric acids. Making these papers 
 is a very delicate operation and it is very necessary that every 
 fresh batch be checked against the papers held as a standard 
 by making tests, using both papers on the same sample of 
 nitrocellulose. 
 
 A. S. T. M. RECOMMENDED TENTATIVE SPECIFICATION 
 FOR SOLUBLE NITROCELLULOSE* 
 
 1. These specifications cover the material known as soluble nitrocellulose, 
 also known as soluble cotton, which is shipped wet to conform to the regula- 
 tions of the Interstate Commerce Commission. 
 
 I. PROPERTIES. 
 2. The material shall conform to the following requirements: 
 
 (a) Appearance—It shall not be discolored and shall be free of lumps 
 and foreign matter, such as charred particles. 
 
 (b) Ash—The maximum ash content allowable is 0.30 per cent, 
 ealeculated on the basis of dry weight soluble nitrocellulose. 
 
 (c) Nitrogen—The per cent nitrogen, calculated on the basis of dry 
 weight soluble nitrocellulose, shall be within the limits agreed 
 upon by the buyer and seller for the particular type of soluble 
 nitrocellulose. 
 
 (d) Stability—The methyl violet test paper shall not be completely 
 changed to a salmon pink color in less than 20 minutes. 
 
 (e) Viscosity—Material shall be within the limits agreed upon by 
 buyer and seller for the particular type of soluble nitrocellulose. 
 
 (f) Solubility and Appearance of the Solution—The sample shall be 
 equal to the standard for the particular type of soluble nitrocellu- 
 lose. 
 
 (g) Film Test—The sample shall be equal to the standard for the 
 particular type of soluble nitrocellulose. 
 
 (h) Toluol Dilution Test—The dilution value of the sample shall be 
 as great as that of the standard for the particular type of soluble 
 nitrocellulose. 
 
 * Prepared by Sub-Com. 25 of Com. D. I.—A. S. T. M. for consideration 
 of committee. 
 
588 Raw Materials Used in Lacquer 
 
 II. SAMPLING. 
 
 3. Samples shall be taken from 2 barrels of each lot or batch in the ship- 
 ment. The composite sample representing a single barrel shall be obtained 
 by taking 2 samples of approximately 1 pint each from 2 well separated points 
 at least 1 foot beneath the surface of the material in the barrel. Each barrel 
 sampled shall be tested and reported separately. 
 
 Ill. METHODS OF TESTING. 
 
 4. The determination of ash shall be made as follows: 
 
 One gram dry soluble nitrocellulose is weighed out in a previously dried 
 and weighed platinum crucible which is then heated to 95°-100° C. to constant 
 weight (about 30 minutes being required). After cooling the nitrocellulose is 
 then moistened with 10-15 drops of C. P. nitric acid and heat the crucible on 
 a steam bath until the sample is decomposed to a gummy mass. It may be 
 necessary to add several additional drops of nitric acid at intervals to com- 
 plete the decomposition. Then heat the crucible slowly over a Bunsen flame 
 or in an electric furnace until all volatile matter is driven off. Finally, ignite 
 at red heat to constant weight. Cool in a dessicator and weigh. 
 
 5. The determination of nitrogen shall be made as follows: 
 
 The nitrogen determination of soluble nitrocellulose is most readily made 
 by means of the nitrometer. A complete description of the apparatus and 
 its manipulation is given in the United States Bureau of Mines Technical 
 Paper No. 160 on “The Determination of Nitrogen in Substances Used in 
 Explosives,’ which can be obtained through the Superintendent of Documents, 
 Government Printing Office, Washington, D. C. Complete description is also 
 given in Worden’s book on “Technology of Cellulose Esters,” page 972. 
 
 The reading and measuring burettes should be accurately calibrated, which 
 is done in the usual manner, using mercury as the calibrating liquid. 
 
 The apparatus must be accurately standardized, and of the two methods 
 given in the above publications the one using absolutely pure potassium 
 nitrate is far preferable. . 
 
 The nitrocellulose should be roughly dried at 50° C., then 1.0 to 1.05 grams 
 are roughly weighed in a tared weighing bottle and dried to constant weight 
 at from 90-100° C. cooling in a dessicator and accurately weighed. The 
 sample is then transferred to the cup of the generating bulb of the nitrometer ; 
 then exactly 25 ec. of the 95% +1% (sp. gr. 1.84) C. P. sulphurie acid used 
 in the standardization of the nitrometer is used to dissolve the nitrocellulose 
 and wash the final traces of nitrocellulose in the weighing bottle and cup of 
 the generating bulb into the generating bulb. The bottom stopeock of the 
 generating bulb must be left open at all times during this operation. Then 
 with the bottom stopcock open and a vacuum on the generating bulb the 
 decomposition is started by gently shaking the bulb. After the rate of decom- 
 position has slowed down, the leveling bulb is lowered enough to draw all 
 but 25 ce. of the mercury out of the generating bulb, the bottom stopcock is 
 closed and the whole vigorously shaken for five minutes to insure complete 
 decomposition of the nitrocellulose. The gas is then allowed to cool and is 
 then transferred to the reading burette and measured. The result is expressed 
 as per cent of nitrogen in the dried samples soluble nitrocellulose. 
 
 It is very important that the bottom stopcock be left open until the major 
 part of the decomposition has taken place, otherwise the sudden, evolution of 
 
Raw Materials Used in Lacquer 589 
 
 gas will rupture the bulb, throwing acid and glass into operator’s eyes and face, 
 causing blindness and deep life scars. Also a cellulose acetate mask should 
 be worn as a safeguard during the entire time of making the test. 
 
 6. The method for stability given in this specification is the method 
 shown on page 582 and is not reprinted here because of lack of space. 
 Pr A. G.). 
 
 7. The “viscosity” of soluble nitrocellulose shall be determined by putting 
 it in solution using a standard formula and noting the rate at which a 
 standard steel ball drops through the solution. 
 
 The 2 solution formulas used are given below: 
 
 % by Weight 
 
 SoA ‘“p”? 
 Soluble Nitrocellulose (dried at 50° C. to constant weight)... 12.2 20.0 
 NE ES oi race we cn os beds cece wep eects weeaceas 17.5 16.0 
 Seeeoemreue rn conol, ©. 1. No. 1 188 '‘Proof..............608% Zoy 20.0 
 POD vies viene ce cise eee 1 BORE Ska ry ORE ot eae i Oia A 48.5 44.0 
 
 Formula “A” shall be used unless the soluble nitrocellulose under examina- 
 tion gives a “viscosity” with it of 6 seconds or less, in which case Formula 
 “B” shall be used. After the soluble nitrocellulose is completely dissolved, 
 fill a glass cylinder having an inside diameter of 1 inch, a height of 14 inches, 
 arid marks on the side 2 inches and 12 inches from the top. Bring the cylinder 
 and contents to 25° C. and allow to stand until all air buihles have passed 
 out of the solution. Then release a standard 5/16 inch ball bearing weighing 
 2.046-2.054 g. (diameter 0.793 cm.-0.797 cm.) at the surface of the solution 
 and allow it to fall through the solution. The number of seconds required 
 for the ball to pass through the 10-inch column of solution between the marks 
 on the cylinder is taken as the “viscosity” of the sample. To this number the 
 letter “A” or “B” is prefixed to indicate the formula used, e. g., “A 8.” 
 
 8. The test for solubility and appearance of the solution shall be made 
 as follows: 
 
 Compare the sample in Formula “A” or Formula “B” with a standard 
 solution of the same type of soluble nitrocellulose in the same formula. The 
 comparison is made in small vials, noting color, turbidity, “grain” and “flock.” 
 When soluble nitrocellulose is to be used for purposes requiring extreme 
 transparency and clarity the sample and standard are compared in the same 
 manner, using Formula “C.” 
 
 EORMULA “CGC” 
 % by Weight 
 Soluble Nitrocellulose (dried at 50° C. to constant weight)........ gees 
 Seuty) Acetate....... ETA ee ets ee ee ie ee ee ee 87.8 
 
 9. The film test shall be made as foliows: 
 
 Thin Formula “A” or Formula “B” with an equal volume of butyl acetate 
 and pour the solution beside the standard on a clean giass plate. Allow the 
 film to dry in a dust free atmosphere and compare sample with standard for 
 
 * Ethyl Acetate 85%—balance unconverted alcohol. 
 
 7+ Toloul 2° boiling range including boiling point of toluene 110.7° G.— 
 non-corrosive. 
 
 + Butyl Acetate 85-90% ester 
 
 balance unconverted alcohol. 
 
590 Raw Materials Used in Lacquer 
 
 a eareer re eneeeeneeee nnn ERNIE EEnenammmnnaemmmamaaatal 
 
 undissolved particles, which indicate un-nitrated cotton or impurities, and for 
 poor flow and poor gloss. 
 
 10. The toluol dilution test shall be made as follows: 
 
 Dissolve the sample according to Formula “C.” To 50 ce. c. of this solution 
 add ce. p. toluol in small quantities from a burette, stirring well after each 
 addition. The first permanent separation of soluble nitrocellulose is taken 
 as the dilution value and is expressed as a per cent by volume of Formula 
 “a.” Large quantities of butyl acetate and toluol should be reserved for these 
 tests to avoid possible variation between different lots. 
 
 TOLERANCE TO DILUENTS 
 
 Nitrocellulose—Two grams of nitrocellulose are dissolved 
 in 20 ec. commercial butyl acetate and titrated with the de- 
 sired diluent until the nitrocellulose is precipitated or the end 
 point is seen in another manner, as described below. The 
 results are reported as the number of ec. of diluent per cc. of 
 solvent (butyl acetate). 
 
 Lacquer Base.—It may be advantageous to know the exact 
 amount of dilution which a lacquer base, probably consisting 
 of nitrocellulose, solvent, gum, and plasticizer, will stand. 
 This laboratory uses the following method: Fifty grams of 
 the lacquer base is weighed out into an Erlenmeyer flask and 
 titrated with the diluent to be used. The results are reported 
 .as ec. of diluent per gram of lacquer base. 
 
 End Points.—The end points in the foregoing determina- 
 tions are rather indefinite, and experience is necessary to be 
 able to check the results. Some diluents throw out the cotton, 
 which can be readily seen. A second class of diluents seems 
 to gradually increase the viscosity of the solution until the 
 entire mass becomes a gel. A third class of diluents is mis- 
 cible with the solution up to the end point where a definite 
 separation of further diluent occurs. 
 
 Testing the Bulking Values of Nitrocellulose.—Dissolving 
 one pound of dehydrated nitrocellulose* in any volume of 
 the following solvent mixture increases the volume 0.0938 
 gallons—as, for example: 
 
 1 lb. Dehydrated Nitrocellulose containing: 0.7 lb. dry ni- 
 trocellulose, 0.3 lb. denatured alcohol dissolved in 1 gal. Sol- 
 vent Mixture consisting of: 0.5 gal. Toluol, 0.5 gal. Butyl 
 Acetate yields in pyroxylin solution 1.0938 gallons. This is 
 known as the bulking value. 
 
 * 70% nitrocellulose and 30% alcohol. 
 
 ere 
 
 Nixes 
 
 oer 
 a’ 
 
 LR eae AS 
 
 picemeien® 
 
 ; 
 5 a 
 
 my 
 
 J 
 
 - 
 
 ire al 
 * 
 
 Wee Om er a 
 5 ve 
 ied Pe 7 hill ‘Aico 
 
Raw Materials Used in Lacquer 591 
 
 In the above mentioned mixture there is no difference in 
 bulking value for Nitrocellulose of different viscosities and 
 concentrations. These results are in terms of absolute den- 
 sity at 25° C.* 
 
 Examination of Lacquer Pigments.—Sub-Committee XXV 
 of the A. S. T. M. has been doing some work with the object 
 in view of describing tests for pigments which are to be used 
 in lacquer. Some of the preliminary suggestions made for 
 the testing of such pigments are given below. 
 
 SAMPLING 
 
 Barrels.—At least 10 per cent of the barrels or kegs in any 
 shipment of white or black pigment shall be sampled and each 
 package shall be tested separately. 
 
 Bags.—When white or black pigments are received in bags, 
 at least 1 per cent of the packages shall be sampled and each 
 package shall be tested separately. For all other pigments, 
 each package shall be sampled and tested separately. 
 
 LABORATORY EXAMINATION 
 
 Bleeding.—This test shall be run only on pigments that 
 are liable to cause bleeding. Mix suitable amounts of the 
 sample under test and the standard with a clear lacquer and 
 spread evenly on a portion of a smooth metal panel. Allow 
 to dry one-half hour, then flow successive coats of white 
 lacquer over the covered portion of the panel and an adjoin- 
 ing area, until complete hiding is obtained. Note whether the 
 colored layer bleeds into the white, which would be indicated 
 by a difference in the color of the two sections of the panel. 
 
 Alternate Method for Bleeding.—Place 0.5 g. of the pigment 
 in a test tube with 25 cc. of the lacquer solvent. Shake, allow 
 to settle and then filter. If filtrate is colored, determine with 
 
 microscope whether it is due to particles in solution or in sus- 
 pension. 
 
 Acidity or Alkalinity.—This test shall be run only on plg- 
 ments that are likely to be excessively acid or alkaline. Shake 
 10 g. of the sample with 100 ce. of 99 per cent methyl alcohol 
 for 30 minutes, using a mechanical shaker. Filter and titrate 
 with N/50 KOH or H2SQ,, using phenolphtalein as indicator. 
 
 *One pound dry nitrocellulose (no alcohol or water bulks 0.0706 gallons). 
 
S92) Os Raw Materials Used in Lacquer 
 
 ES 
 
 Express results as mgs. KOH required to neutralize 1 g. of 
 sample, or as mgs. KOH in 1 g. of sample. 
 
 Moisture and Other: Volatile Matter—The moisture shall 
 be determined as follows: 
 
 Method ‘‘A’’—for colors that do not decompose at 110 de- 
 grees C. Place 5 to 10 g. of sample in a weighed aluminum 
 moisture dish with a tightly fitting cover and weigh. Par- 
 tially remove cover and heat at 105 to 110 degrees C. for two 
 hours. Replace cover, cool in a dessicator and weigh. Repeat 
 heating for periods of half an hour until constant weight is 
 reached. Report the total loss as moisture and other vola- 
 tile matter. In this determination the cover of the moisture 
 dish should be removed only to receive the sample and when 
 heating in the oven. 
 
 Method ‘‘B’’—for colors that decompose at 110 degrees C. 
 Method to be developed. The methods proposed for consid- 
 eration are drying in a vacuum oven and the Standard Meth- 
 od of Test for Water in Petroleum Products and Other Bitu- 
 minous Materials, A. 8. T. M. Standards, D 95—24, with the 
 following variations and additions: 
 
 The sample shall be 25 g. The solvent shall be 79 ce. of 
 xylol, previously saturated with water by shaking with an 
 excess of water in a separatory funnel, drawing off and dis- 
 tilling. The distillation shall be continued until the distillate 
 comes over clear and the condenser then washed down with a 
 cotton swab saturated with xylol.. From the volume of water, 
 caleulate the percentage by weight. 
 
 Testing Lacquer Solvents.—The tentative methods of tests 
 adopted at the June, 1927, meeting of the A. 8. T. M. are pre- 
 sented below: 
 
 A.S.TL.M. TENTATIVE METHODS OF SAMPLING 
 AND TESTING 
 
 LACQUER SOLVENTS’ AND DILUENTS 
 1. These methods cover the sampling and tests to be applied to solvents and 
 
 diluents for use in the manufacture of nitro-cellulose lacquer. 
 
 SAMPLING 
 2. (a) The method of sampling specified in Paragraph (b) or (ec) shall 
 be used, according to the special conditions that obtain. 
 
 (b) From Loaded Tank Car or Other Large Vessel.—The composite sample — 
 
 taken shall not be less than 4 gal. and should consist of small samples of not 
 more than 1 qt. each, taken from near the top and bottom by means of a metal 
 or glass container with removable stopper or top. This device, attached to a 
 
 suitable pole, shall be lowered to the desired depth, when the stopper or top — 
 
 shall be removed and the container allowed to fill. 
 
 powr- ey gp ee Sa es wae aT 
 
 Oe eee ere nee 
 
Raw Materials Used in Lacquer 593 
 
 (c) Barrels and Drums.—At least 5 per cent of the packages in any ship- 
 ment shall be represented in the sample. The purchaser may increase the 
 percentage of packages to be sampled at his discretion, and it is recommended 
 that every package be sampled in the case of expensive solvents that are 
 bought in small quantity. A portion shall be withdrawn from about the center 
 of each package sampled by means of a “thief” or other sampling device. The 
 composite sample thus obtained shall not be less than 1 qt. and shall’ consist 
 of equal portions of not less than 1% pt. from each package sampled. 
 
 METHODS OF TESTING 
 
 3. Specific gravity shall be determined for all solvents and diluents. The 
 determination shall be made at 20° C. by any convenient method that is 
 accurate to the third decimal point. 
 
 4, Color shall be determined for all solvents and diluents. The sample 
 and the standard mutually agreed upon by the buyer and seller shall be 
 compared in 50-cc. Nessler tubes against a white background. For a solvent 
 to be rated water-white, the visible color shall not be darker than a solution 
 of 0.0030 g. of potassium bichromate in one liter of water. 
 
 5. The distillation test shall be conducted on all solvents and diluents, 
 in accordance with the Tentative Method of Test for Distillation of Gasoline, 
 Naphtha, Kerosine, and Similar Petroleum Products (Serial Designation: D 
 86-26 T) of the American Society for Testing Materials,* except that the 
 observations made shall be not of volumes of distillate coming over at certain 
 specified temperatures, but of the temperatures at which certain specified 
 volumes of the distillate come over. The temperature shall be observed and 
 recorded at first drop of the distillate, and when the volume of the distillate 
 collected, observed to the nearest 0.5 ce., reaches 5 ce, 10 cc, 20 cc, 30 
 ec., 40 ec., 50 ce., 60 ce., 70 ec., 80 cc, 90 cc., 95 cc., and end point. 
 
 6. The residue shall be determined for all solvents and diluents. Using 
 a pipette, 5 ec. of the sample and of the standard shall be placed in separate 
 porcelain evaporating dishes. These samples shall be allowed to evaporate 
 in a hood for 24 hours. If any residue remains, its nature shall be noted and 
 the test for non-volatile matter shall be made as described in Section 7. 
 
 7. Non-volatile matter of solvents and diluents shall be determined only 
 when its presence is indicated by the results obtained in Section 6. One 
 hundred cubic centimeters of the sample shall be placed in a weighed porcelain 
 evaporating dish and evaporated almost to dryness on a steam bath. It shall 
 then be heated in an oven at 100 to 110° C. to constant weight. The increase 
 in the weight of the dish is the non-volatile matter of the sample, which should 
 be expressed as a percentage, calculating the weight of the sample from its 
 specific gravity, determined as described in Section 3. 
 
 8. Residual odor shall be determined for all solvents and diluents in which 
 residual odor is an important property. Strips of heavy filter paper, of the 
 same size and shape, shall be dipped to the same depth in beakers or wide- 
 mouthed bottles containing the sample and the standard. They shall then be 
 attached to a piece of wood. with thumb tacks and at suitable intervals exam- 
 ined for difference in odor. 
 
 * Proceedings, Am. Soc. Testing Mats., Vol. 26, Part I, p. 816 (1926) ; also 
 1926 Book of A.S.T.M. Tentative Standards, p. 388. 
 
594 Raw Materials Used in Lacquer 
 
 9. Water shall be determined for all solvents and diluents. Five cubic 
 centimeters of the sample shall be transferred to a 100-cc. glass-stoppered 
 cylinder, and 60° Baumé gasoline added in 5-ec. portions, shaking well after 
 each addition. Water is indicated by turbidity. If turbidity develops, the 
 standard shall be tested in the same way and compared. 
 
 10. Acidity shall be determined for all solvents and diluents. Using a 
 pipette, 50 cc. of the sample shall be transferred to a small Erlenmeyer flask 
 
 and titrated with 0.1 N KOH in 99-per-cent methyl alcohol, using phenoph- — 
 
 thalein as an indicator. The weight of the sample shall be determined 
 from the specific gravity and the acidity reported as milligrams of KOH per 
 gram of sample. 
 
 11. Alkalinity of solvents and diluents shall be determined only when 
 indicated by the results obtained in Section 10. Using a pipette, 50 cc. of the 
 sample shall be transferred to a small Prlenmeyer flask and titrated with 
 0.1 N H.SO,, using methyl orange as an indicator. The weight of the sample 
 shall be determined from its specific gravity and the alkalinity reported as 
 milligrams of KOH per gram of sample. 
 
 12. Ester value shall be determined for all esters. One to two grams of — ig 
 
 the sample shall be weighed in an ampoule, by first weighing the empty 
 ampoule, warming and filling, and then sealing-off and re-weighing. The 
 ampoule shall be placed in a 200-ce. Erlenmeyer flask which contains 50 ce. 
 of approximately 0.5 N alcoholic KOH. The ampoule should be broken with 
 a stirring rod and the flask connected with a reflux condenser. The flask shall 
 then be heated on a steam bath for one to four hours, depending upon the 
 ester being tested. During the heating the set-up and contents should be shaken 
 frequently, taking the usual precautions to lose none of the contents. After 
 the apparatus has cooled, the condenser shall be washed down with distilled 
 water and three drops of phenolphthalein added to the contents of the flask 
 as an indicator. The contents of the flask shall be titrated with 0.5 NV HCL 
 Two blanks with alcoholic KOH shall be run along with the sample. These 
 blanks should check to the first decimal point. The result shall be reported 
 as percentage of ester by weight, allowing in the calculations for acidity or 
 alkalinity as determined in Sections 10 and 11. 
 
 NOTE.—An optional method of weighing the sample is in a small weighing 
 bottle, removing the stopper after introduction into the flask with a stirring 
 rod, or by agitating the contents of the flask. Apparatus with glass joints 
 should be used if available. 
 
 13. A copper corrosion test shall be run on solvents and diluents derived 
 from coal tar and petroleum. A clean strip of mechanically polished pure 
 sheet copper, about 1 in. square, shall be placed in a 4-in. porcelain evaporating 
 dish and covered with 100 ec. of the sample. This shall be covered with a 
 watch glass and heated on a steam bath for 30 minutes. The liquid shall be 
 poured off and the copper examined. for blackening. A slight tarnish shall 
 be disregarded, but any marked blackening shall be cause for rejection. 
 
 Se ee oe ae ee 
 
CHAPTER XXXV 
 
 ANALYSIS OF PYROXYLIN COATINGS 
 
 The writer is indebted to H. D. Bruce of the Bureau of 
 Standards and to J. B. Wiesel and Hugo Schlatter for aid in 
 the preparation of the schemes of analysis which are presented 
 herein. It should be stated, however, that no comprehensive 
 scheme of analysis has yet been devised which may be con- 
 sidered suitable for all types of nitrate lacquers. In the analy- 
 sis of such lacquers, much depends upon the experience and 
 ingenuity of the analyst. He must obtain clues as to the in- 
 gredients present, and must then devise methods to suit the 
 particular mixture at hand. The separation, identification, 
 -and quantitative determination of mixtures of organic sol- 
 vents, particularly those of similar chemical and physical 
 properties, and those yielding constant boiling mixtures, are 
 very difficult procedures. The experienced analyst will find a 
 physical examination of the lacquer of great value in obtain- 
 ing clues as to the identity of the solvent mixture. The deter- 
 mination of the specific gravity, viscosity, color, luster or dull- 
 ness upon drying, behavior upon flowing on glass or spraying 
 on sheet metal, thickness of film obtained, and the detection 
 of the various solvents and thinners by odor, will all be of 
 great aid in judging the probable composition of a given lac- 
 quer. For methods of making physical tests on lacquer the 
 reader is referred to Chapter XXXVI. 
 
 In the analysis of lacquers, considerable information may be 
 obtained in a preliminary way. The lacquer may be precipi- 
 tated by adding an excess of hydrocarbon such as toluol, the 
 mass then filtered, and the filtrate evaporated to determine the 
 amount of oils, gums and plasticizers present. The residue 
 from evaporation may be examined to determine the type of 
 oils and gums used. The precipitate which consists of nitro- 
 cellulose and pigment may be treated with a solvent such as 
 acetone to remove the nitrocellulose, the pigment then being 
 examined. The acetone solution of nitrocellulose may then 
 be treated with water to throw out the nitrocellulose. The 
 above in general is the method used in many laboratories. 
 
 _Itis a difficult matter to determine the percentages of plas- 
 ticizers present. Qualitative information, however, may be 
 
596 Analysis of Pyroxylin Coatings 
 
 obtained by boiling a small portion of the non-volatile residue 
 of a lacquer with sodium hydroxide, and then acidifying. If 
 tricresyl phosphate is present, the odor of cresol will be de- 
 tected and the presence of phosphates may be looked for. If 
 the distillate from a lacquer is examined, 1 ec. may be added 
 to 1 ce. of water and 1 cc. of mixed nitric-sulphuriec acids. The 
 characteristic odor of nitrobenzol indicates the presence of 
 benzol as a diluent. 
 
 Camphor is usually present in pyroxylin solutions, in which 
 scrap celluloid is used as the base, or in pyroxylin solutions 
 when a high boiling latent solvent is needed, such as in mantle 
 dips. When more than one or two per cent camphor is pres- 
 ent, the camphor content should be determined by the refract- 
 ometer. When analyzing a solution which contains scrap cel- 
 luloid as a base, about 20% of the weight of the nitrocotton, 
 as determined by the total solids determination, should be 
 added to the total solids determination in order to get the 
 percentage of scrap celluloid used. The camphor type of py- 
 roxylin solution is easily recognized after some experience in 
 working with such solutions, and it is seldom necessary to use 
 the refractometer in evaluating the pyroxylin solution. 
 
 In determining whether a low, medium or high viscosity 
 type of soluble cotton was used in the solution, the viscosity 
 determination and the nitrocotton content of the solution are 
 taken into consideration. From the weight per gallon deter- 
 mination and the specific gravity of the distilled solvent, the 
 ounces of nitrocotton per gallon of solution may be determined. 
 
 Soluble cotton ranges in nitrogen content from about 11 to 
 12.6 per cent, the former being used for celluloid and similar 
 plastics, the latter for smokeless powder. Hither of these 
 varieties or any in between these two extremes may be met 
 with in present day lacquers. The nitrogen content between 
 the limits stated) alone is, however, no indication of the suita- 
 bility of a soluble cotton for any particular purpose, and it 
 may not bear any direct relation to viscosity or solubility in 
 any particular solvent. 
 
 In examining the thinner or diluent used in a lacquer, if 
 the fruit-like odor of acetates is not noticeable in the various 
 fractions, it will not be necessary to run a saponification test. 
 In determining the type of resin used, the chart appended on 
 
Analysis of Pyroxylin Coatings 597 
 
 pages 098-9 may be of general service, as well as the methods 
 for oil and resin analysis given in Chapter XXIV. 
 
 Materials to Look for in Pyroxylin Coatings. There is given 
 below a list of the more important materials used in pyroxylin 
 coatings. While many hundred products have been proposed, 
 those listed below are the ones most commonly used. 
 
 Solvents Ethyl, Butyl, and Amy] Acetates; Ethyl Lac- 
 tate, Acetone Oil, Methyl-Ethyl Ketone, Fusel Oil, Ethyl and 
 Methyl Alcohols, Butyl Alcohol, Acetone, Benzol, Xylol, To- 
 luol, Gasoline, Acetic Ether, Acetone Oils, Anhydrous Ethyl 
 Alcohol (Ansol), Butyl Propionate, Diacetone Aleohol, Di- 
 ethyl Carbonate (Diatol), Ether-Alecohol, Ketones, Methyl 
 Acetate, Methyl Acetone, Mono Kthyl Ether of Ethylene Gly- 
 col (Cello-Solve), Amyl Aleohol, Butyl Aleohol (Butanol), 
 Ethyl Alcohol (Ethanol), Isopropyl Alcohol, Methyl Alcohol 
 Methanol), Secondary Butyl Alcohol. 
 
 Plasticizers and Stabilizers.—Diethyl Carbonate, Tricresyl 
 Phosphate (Lindol), Diethyl Phthalate, Urea, Camphor, Cas- 
 tor Oil, Diamyl Phthalate, Dibuty| Phthalate, Dibutyl Tar- 
 trate, Linseed Oil, Rape Seed Oil, Tung Oil, Triacetin, Tri- 
 phenyl Phosphate. 7 
 
 _ Oils.—Castor Oil, Linseed Oil, or Rape Seed Oil usually 
 in blown or heavy bodied form. 
 
 Resins.—Copal, Kauri, Pontianac, Manilla, Shellac, Damar, 
 Rosin, Ester Gum, and Phenol-Colophony or Phenol-Formal- 
 dehyde Condensation Resins. 
 
 Cotton.—Usually regular Soluble Nitrated Cotton of low 
 viscosity. Smokeless Powder reduced in viscosity and Cellu- 
 loid Movie Film are also used. Cellulose Acetate, because of 
 its higher cost, is rarely used in commercial lacquers. 
 
 Pigments.—Usually high strength toners, C. P. chemical 
 colors, high strength blacks, and finely ground mineral or 
 chemical colors of greatest hiding power. 
 
 Schemes for Analysis of Lacquers. —There are given below 
 two schemes for the analysis of nitrocellulose lacquers. Both 
 have been used quite extensively with satisfactory results. 
 
 LACQUER ANALYSIS (Scheme No. 1.) | — 
 
 Weight per Gallon Determination—The pyroxylin solution 
 is adjusted to a temperature of 20° ©., and weighed in a 
 
598 Analysis of Pyroxylin Coatings 
 
 aprdo]yIvdAja [ UOQ4D) ~|ulH|[alolole|alajole|o 
 
 IYjaaY 111901) alH|Hlalolalolaj|e 
 
 H | A 
 majong) = |= [=| [2 |o|o fale [ele 
 nore toil (= [= [=| [= [= fle led 
 wnsini||-.|= [0] oo fe fee 
 
 [a= 
 
 IULOS DE) ~|u|+falolafa wn 
 
 awval [|= [| ala] [=| fale 
 wy | n(n (| [oo fo[m [fe [ 
 
 aypuorgorg 1KIng ~Jol4jelololalefa|aia|. 
 “eatin macdod fo ua) \n|~|0|alalalo|o|ele|e 
 word] |o|~|a]o[olololalalole 
 
 wd o|ol=-|-lole ele 
 
 164990 Blol.|ololalalelalelo|- 
 
 SOLUBILITY AND MISCIBILITY OF LACQUER MATERIALS 
 
 wal = [|| [| a | fo] [fle 
 pyory Kua) o|~|.lalalalalo|o|8|Ble 
 
 armory ural B | on | op) nlololalalolole 
 joyonny auorsrmia) yy | ol larla fale feo fe |e |e |e 
 aypaking 1kjng = | = cc wa | 0 Ora a 2 Me Fe 
 
 oyory Kma| Bl || falalale Nn a\o le 
 amroy ing), | os ~|olalolale|- }2\4|4 
 owony uy] B\ | ja lolalo|ola|a lala n nlalnlalole 
 nny xuy| [ola [a|alolo|o|Blolale 
 
 obo ee e 8 2 
 Seeas e ae tel o | BY 
 a oe HH ! 
 Ae ae g WPeicee a| |e | 
 M4 n.4 nm Oy Fes 3 Ne} a 5 o eee oO Ni 5 ow 
 Beet s/elsi Ble] 2 siels aA 
 Dyn on E/S15)2)3| Slelelzigigis 
 S/SISISISINISlalelolala 
 
599 
 
 Analysis of Pyroxylin Coatings 
 
 apldojyIDAJa J. WOGADD| Ay | 
 
 "LOOATL) ouUSTAYY JO SIOUIA » 
 
 MAO{OLO]YI| Ax | 
 
 HOVN %0I 
 
 aDjaap AMY Fs 
 
 wins) J94sq 
 
 UISOY 
 
 reqizuez wintry 
 
 ouoreund wins 
 
 Joydweg uns 
 
 rewmueq ums 
 
 onseyy wins 
 
 S Ajjred—g 
 s[[JaMsS—y 
 of Nd ete | 
 ATWYSIS—SS 
 ajqnjtos—s 
 Ady 
 
 S > > S S > S S ss SEE Stes) S I S = S S S S 
 S 5 S S re ) re S S S = > S 2 S 5 I S =) 
 I I d I i SSainoenoes Sooo os 4. Si So Leos I > 
 S d S 3 = S 5 S SS) . S S I a S ~ I S I 
 S = S S Ss S > iS) 5 S S S S S S) S a 5 5 
 =) d = = d = d d d S d > dy ac I S d | SS d 
 d SS d Sontcos S S Stal eeeatts hs pasa theo I = I I 
 d SS Sled > > ) S S S S S S S S ~ 5 5 
 ie i ae a Pee a wd ae oe ewe aoe ke a cos: aie con Rese e ny mele ise Eee os 
 SS PORT Spey SR hr eR a ee oe en eee ele a ee 
 Woy Sob Se Si Se ses rt Se | Cea eet eae Aimee eee a 
 SS ad ed ee Paseo rp on ere ee eta feed ae Pele-be ech [ * 
 S. S by > > ~ = eS =~ 5 ~ 
 3 2. S Ae is} = Sv Ss = S 
 S & > | x gig bie ed ted Ps te eg esha 
 = = = S Sates 8 S) ~ S 
 Q Q pst =, coy 
 ® NS iS Ss 
 ~ = 
 iss) 
 D 
 S 
 S 
 
 penujuopo—STVIYALVW YANOOVI AO ALITIGIOSIN GNV ALITIANTOS 
 
600 Analysis of Pyroxylin Coatings 
 
 marked cylinder; the weight of the equivalent volume of water 
 at the same temperature being previously determined. 
 
 Weight of pyroxylin solution 
 
 wo 
 Weight of equivalent volume of water P S y 
 
 Specific gravity x 8.34 = Weight per gallon 
 
 Specific Gravity—The specific gravity determination is 
 made as outlined above or with a pyenometer. The determi- 
 nation is made at 15.5° C. . 
 
 Effect on Metal—Much information can be obtained regard- 
 ing the non-corrosive properties of a clear lacquer or of the 
 solvents to be used in a lacquer, by evaporating 50 cc. in a 
 brightly polished spun copper dish. The presence of sulfur 
 compounds in the lacquer solvents will be disclosed by brown, 
 red or purple stains on the copper dish. The presence of free 
 acid in the solvent, usually developed by the hydrolysis of the 
 esters, or of free acid developed in lacquers from unstable 
 nitrated cotton, will cause a green discoloration. The evap- 
 oration may be made on a steam bath. The residue, if any 
 is present, may be weighed. 
 
 Free Acidity —Add to 20 gms. of a clear lacquer, with con- 
 stant stirring, 40 ee. of a neutralized mixture of 50 per cent de- 
 natured aleohol and 50 per cent of water. Then add diluted 
 neutralized denatured alcohol until all the solids are precipi- 
 tated and the supernatant liquid is clear. This liquid is then 
 decanted and the precipitate washed by decantation with a 
 small amount of neutralized denatured alcohol. The decanted 
 liquid and washings are then titrated with N/10 sodium hy- 
 droxide, using phenolphthalein as indicator, until a faint pink 
 color persists for at least ten seconds. To neutralize the 
 denatured alcohol in the above procedure, add a few drops of 
 phenolphthalein indicator, and then N/10 sodium hydroxide, 
 drop by drop, with constant stirring, until a faint pink color 
 appears. 
 
 Pigment Separation—tThe separation of pigments from a 
 pigmented lacquer is usually a very difficult thing. Hven when 
 as low as 10 grams of pigmented lacquer are thinned with as 
 high as 100 grams of a mixed solvent, and centrifuged for an 
 hour, the collodial nature of the lacquer is often such as to 
 
 Se a EN aT Oe eT Oe LT ew NR ee em ee TE AC eee eee eRe ey ee Aa Serene eT ke ashen iis eee anemia 
 
Analysis of Pyroxylin Coatings 601 
 
 cause some finely divided pigments to remain in suspension. 
 Filtering through double layers of filter paper will not remove 
 such pigments. For this reason, it is customary in many in- 
 stances to ash a 20-gram sample of the lacquer at low tempera- 
 ture, first having gotten rid of the volatile constituents by 
 evaporation. ‘The residue from ignition may be examined in 
 accordance with the methods outlined for the examination of 
 pigments in other chapters of this book. Zine oxide, litho- 
 pone, and titanium oxide are the pigments usually used in 
 white lacquers. 
 
 Total Solids (Method A).—Evaporate carefully, to constant 
 weight, on a friction top can lid, a 2 gm. sample of the lacquer, 
 Birting occasionally to break ne ‘¢skin’’ which forms at the 
 surface upon the evaporation of the solvents. The solid resi- 
 due upon evaporation may consist of cellulose nitrate, mix- 
 tures of cellulose nitrate, plasticizers, or various resinous and 
 oily materials, in the case of clear lacquers, or these various 
 ingredients mixed with pigments in the case of pigmented 
 lacquers. This method is not as accurate as method B on ac- 
 eount of the difficulty of getting rid of the last traces of sol- 
 vents. 
 
 Total Solids (Method B).—A sample (5 to 10 grams). is 
 weighed out as rapidly as possible in a tared aluminum can 
 with a tight fitting cover or by difference from a weighing 
 bottle. About 100 ce. of an ether-alcohol mixture (2 to 1) is 
 added, and the mixture stirred until a homogeneous mass is 
 obtained. The ether-alcohol solution is then brought to a boil 
 over a hot plate or a steam bath and 25 cc. of water is added 
 very slowly, with continual stirring. The stirring is then 
 continued until the solvent is evaporated off. The stirring is 
 essential, in order to avoid the formation of collodial precipi- 
 tates. If the precipitation is carried out as outlined, a 
 stringy precipitate is obtained. <A precipitate in this form 
 dries more easily than a lumpy precipitate. The solution is — 
 evaporated to dryness on a steam bath, and then placed in an 
 oven at 100° C. + 1° C. for two hours; cooled in a dessicator 
 for a half (74) hour and then weighed. 
 
 weight of evaporated material in aluminum can X 100 
 
 —= per 
 weight of sample 
 
 cent total solids. 
 
602 Analysis of Pyroxylin Coatings 
 
 If a cloud is formed on the addition of water to the ether-alco- : 
 
 hol solution, the presence of camphor is indicated. When 
 camphor is present, it 1s necessary to make two or three addi 
 tions of water, evaporating to dryness after each addition in 
 order to drive off all the camphor. The percentage of cam- 
 phor may be determined by the refractometer. The presence 
 of oil in this pyroxylin solution is indicated by an oily feel and 
 appearance of the total solids residue. The presence of gums 
 is sometimes indicated by the odor or by the dark brown ap- 
 
 pearance and brittleness of the total solids residue. When a 
 
 oils or gums are present, a weighed portion of the total solids 
 
 residue is placed in a paper thimble, and is extracted with a 
 
 solvent in a Soxhlet extraction tube for four hours. Chloro- 
 form is a good solvent for Damar, Ester Gum or Mastic, but is 
 unsuitable for Sandarac, Cumar or Copal. Benzol is good for 
 many resins but unsuitable for Shellac, Sandarae or Copal. 
 
 Butyl Alcohol is the best general solvent to use. The solvent — 
 
 containing the oils or the gums im solution is transferred to a 
 tared beaker and evaporated to dryness. Increase in weight 
 divided by the weight of the sample times 100, gives the per- 
 centage of oils and gums in the total solids. To identify the 
 
 oil or gum used, see methods of oil and resin analysis, else- — 
 where in this volume. The acid value, iodine number, and — 
 saponification number of this residue will give much informa- — 
 
 tion. 
 
 Volatile Constituents.—Distill a sample of approximately 
 
 150 grams of the lacquer, in steam. Add to the distillate suf- — 
 
 ficient sodium chloride to make a 20% solution of the aqueous 
 layer, thus ‘‘salting out’’ certain of the solvents and thinners. 
 Separate the two layers, oily and aqueous. Fractionate the 
 aqueous layer, which should contain aleohol and acetone, if 
 
 present. The presence of alcohol can be detected in the higher ~ 
 
 boiling fraction. Also look for Ethers of Ethylene Glycol. 
 The oily layer is referred to below for further examination. 
 
 Sulphuric Acid Insoluble-—Equal volumes of cold 95% sul- 
 phuric acid and the oily layer secured as under determination 
 of volatile constituents are placed in a glass-stoppered gradu- 
 
 ated cylinder. The acid should be added very slowly with — 
 continued agitation. The mixture is well shaken and allowed 
 to stand until there is a complete separation. The volume ~ 
 of the upper layer is the amount of distillate insoluble in sul 
 
Analysis of Pyroxylin Coatings 603 
 
 phurie acid. These are hydrocarbons such as benzol, toluol, 
 etc. 
 
 Saponification Value-——Duplicate samples of from four to 
 seven grams of the ‘‘oily layer’’ dried over fused calcium 
 chloride are weighed into a pressure flask. Fifty cc. of ap- 
 proximately normal alcoholic KOH is added. The pressure 
 flask is heated in an oven at 100° C. for one hour. It is ad- 
 visable to wrap the pressure flask in a towel before placing 
 in the oven, as there is danger of explosion. The flask should 
 be shaken three or four times while being heated. A blank 
 determination is made on the alcoholic KOH at the same time 
 as the distillate is being saponified. The saponified material 
 in the pressure flasks is allowed to cool, and is then titrated 
 with N-2 HCl, using phenolphthalein as an indicator. One ce. 
 of N/1 alcoholic KOH is equivalent to 0.008 grams of ethyl 
 acetate, or 0.1301 grams of amy] acetate or 0.1055 grams buty| 
 acetate. 
 
 If, after deducting the sulphuric acid insoluble portion, the 
 saponification number is between 400 and 500, it is probable 
 that amyl acetate is the only other constituent of the oily layer. 
 However, since butyl acetate is now being used in such lac 
 quers, one must not place too much reliance upon the quanti- 
 tative analytical data without actually determining the nature 
 of the ester present. It must be borne in mind that these 
 analytical data are only indiccations as to the nature of the 
 materials present. 
 
 Should the saponification number, however, be above 500, 
 the presence of esters of lower alcohols is indicated. It will, 
 therefore, be advisable to fractionate the oily layer to sepa- 
 rate these esters. The fraction distilling below 85° C. is col- 
 lected separately from that distilling above 85° C. That pass- 
 ing over below 85° C. is probably composed of ethyl acetate, 
 gasoline, or benzol, or mixtures of these substances. In the 
 absence of ethyl acetate, this fraction should be completely 
 insoluble in cold concentrated sulphuric acid. The higher 
 boiling fraction is generally composed of amyl or butyl ace- 
 tate, or mixtures of both, contaminated possibly by some free 
 amyl or butyl aleohol. High boiling hydrocarbons, such as 
 xylene, are also occasionally used. The presence of such hy- 
 drocarbons can be best detected by their insolubility in cold 
 eoncentrated sulphuric acid as outlined above. 
 
604 Analysis of Pyroxylin Coatings 
 
 After fractionating the oily layer, the sulphuric acid insolu- 
 
 ble portion of each fraction is determined. Saponify each 
 fraction by the method above. Deduct from the total amount 
 of each fraction the amount of hydrocarbons present before 
 
 calculating the saponification number. This will give an in- — | 
 
 dication of the nature and quantity of the esters present. 
 Technical ethyl acetate, which may be present in the lower 
 boiling fraction, has a saponification number of 600-635. 
 
 Glycol Solvents.—Since the preparation of Methods 1 and 
 2 referred to above, solvents of a glycol base have come into 
 the industry. The principal one is the ethyl ether of ethylene 
 glycol, known commercially as Cello Solve. The material is 
 soluble in water and should therefore be obtained in the water- 
 soluble extract in analytical work. In an attempt to deter- 
 mine whether a mixture of this material with butyl alcohol 
 could be fractionated, the boiling ranges were determined. 
 With butyl alcohol, the first drop started at 116° C., and 98% 
 distilled over at 118° C. With Cello Solve the ranges were 
 from 130.5° C. to 135° C. With a mixture of equal volumes, 
 
 the first drop came over at 116° C. and the last drop at 135° . 
 
 C. 
 
 From these data it would appear that there could be no 
 sharp separation by distillation. The densities of the mate- 
 rials are 0.936 for Cello Solve and 0.810 for butyl alcohol. 
 
 These might afford a means for distinction and possibly as a — 
 
 basis for analysis. Moreover, it is possible that Cello Solve 
 
 might be converted to glycol and the latter separated by dis- 
 
 tillation, but no convenient method for so doing is at present 
 available. The fact, however, that Cello Solve is soluble in 
 water may aid the analyst in detecting this material. It has 
 very remarkable solvent properties upon nitrocellulose, and 
 is practically odorless. 
 
 Tests for Butyl and Amyl Alcohol_—An interesting quanti- 
 tative test for distinguishing between butyl and amy] alcohols, 
 namely, the Pettenkoffer furfural reaction, is given below: 
 
 A drop of the unknown substance mixed with 5 ec. of water 
 (plus ethyl alcohol if the substance is very insoluble) and a 
 drop of very dilute aqueous furfural solution, about 0.1 per 
 cent, are mixed in a test tube. Several ec. of concentrated 
 H.SO, are introduced beneath the aqueous layer. <A purplish 
 ring at the juncture of the two liquids results in the presence 
 
 : . ‘ by eee — ‘ er - , 
 ee eee rr: S F ar ah iy era Te eee ee - Ec ahi yl a 
 see iis rin PN FN ER OE Praline tal OF mo ee é pd ‘Pec hel “ie 4 i oY : 
 
 ~ Bn Se OP egy f. i Z 4 na a 
 
Analysis of Pyroxylin Coatings 605 
 
 of amyl alcohol. This color forms within a period of one 
 minute and is quite permanent. A brownish decomposition 
 ring should not be confused with the purple-red color. Many 
 substances give this color reaction, such as a-naphthol, mor- 
 phine, oleic acid, cholalic and other bile acids, but none which 
 might be confused with amyl alcohol as a lacquer constituent. 
 
 LACQUER ANALYSIS (Scheme No. 2.) 
 
 Separation of Solids and Liquids.—Weigh out a 400 gram 
 sample of the lacquer into a liter flask. Add 400 cc. of water, 
 shake thoroughly, and then distill, having the flask immersed 
 in a castor oil bath to prevent superheating and consequent 
 decomposition. Use a water cooled glass condenser, and a 
 large separatory funnel as receiver. Distill only to a tem- 
 perature of 100° C. <A higher temperature may decompose 
 the nitrocotton. By this steam distillation the solvents are 
 separated from the solids. Remove the solids from the dis- 
 tillation flask and dry thoroughly at a temperature of 60° C. 
 Set aside for later examination. 
 
 Separate the two layers of the distillate. Shake the water- 
 insoluble layer with 50 ec. portions of distilled water to remove 
 all possible traces of the water-soluble solvents. The water 
 solution should not be made over 600 cc. if possible. 
 
 Examination of Water-soluble Solvents.—Look for acetone, 
 methyl alcohol, methyl acetate, ethyl alcohol, ethyl acetate, 
 butyl alcohol,* soluble high ketones, and ethers of ethylene 
 glycol, ete. The water solution of the above solvents are frac- 
 tionated through a column as illustrated in Figure—. 
 
 The temperature at which the first drop distills is recorded 
 and fractions are cut as follows: 
 
 Ist cut—74° C., acetone, methyl] alcohol, and methyl acetate. 
 
 2nd eut—74°—80° C., ethyl alcohol and ethyl acetate. 
 
 3rd cut—80°—100° C., butyl alcohol, small amounts of butyl 
 acetate, and possibly water-soluble ketones. 
 
 Analysis of the first fraction containing acetone, methyl 
 alcohol, and methyl acetate is conducted as follows: 
 
 Methyl acetate.—Saponify an aliquot portion of the first 
 fraction. Use N/3 alkali. Reflux for 2 hours. Titrate with 
 N/3 H2SO,, using phenolphthalein as indicator. 
 
 * Slightly soluble in water. Very soluble in water in presence of ethers 
 of ethylene glycol. 
 
606 Analysis of Pyroxylin Coatings 
 
 CONDENSER 
 
 METAL WATER 
 JACKET FILLED WITH 
 STILL WATER AND THEN 
 STOPPERED 
 
 RUBBER STOPPER 
 
 PIPE WRAPPED WITH TAPE 
 OR ASBESTOS INSULATING 
 MATERIAL 
 
 sat]| “RON PIPE CONDENSER 
 4} /S/NCH IN DIAMETER 
 
 B31 AILLED WITH PEBBLES 
 
 KEPT IN WITH [RON LUG 
 
 GUY 
 
 /-L/TRE COPPER FLASH 
 
 SUPPORT AT FLOOR LEVEL 
 
 FIGURE 199 
 
 Fractionating Column for Lacquer Solvents similar to that used by 
 Taylor and by Bruce. 
 
Analysis of Pyroxylin Coatings 607 
 
 Acetone.—Shake 2 ce. of the first fraction with 300 ee. of 
 fresh lime water. Add N/10 iodine solution in small portions 
 with vigorous shaking. The acetone reacts to form iodoform 
 which erystallizes out as lemon yellow crystals. Make slightly 
 acid with dilute H2SO,. At this point a deep brown colora- 
 tion should result if sufficient iodine has been added. Titrate 
 excess iodine with standard Na2SeOs. 
 
 Reactions. 
 
 2 Ca(OH )2 + 2I2 >Cal? + Ca(Ol)e + 2H20 
 3 Ca(OI),. + 2CH3COCH, > (CH;COO).Ca + 2Ca(OH)> 
 + 2CHIs 
 (Note: NaOH solution cannot be used in place of Ca(OH):2 water, inas- 
 
 much as certain alcohols which may be present in small amounts react with 
 the former in the presence of iodine to form iodoform.) 
 
 Methyl Alcohol.—This may be obtained by difference. 
 
 Analysis of the second fraction (80° C.) containing ethyl 
 aleohol and ethyl acetate is conducted as follows: 
 
 Hthyl acetate.—Determined by saponification of a small 
 aliquot portion, about 4 or 5 grams. 
 
 Ethyl aleohol.—Obtained by difference, assuming the alco- 
 hol solution to be 95% pure, if ethers of ethylene glycol are 
 not present. 
 
 The third fraction of the water soluble solvents (100° C.) 
 may contain butyl alcohol, butyl acetate, and possibly high 
 ketones. Ina separatory funnel, salt out with NaCl in excess 
 and add the top oily layer containing the butyl compounds, 
 etc., to the water-insolubles. 
 
 Examination of Water Insoluble Solvents.—Look for ethyl 
 acetate, butyl alcohol, butyl acetate, amyl acetate, heavy ke- 
 tone oils, benzol, toluol, xylol, gasoline, ete. Dry the water 
 insoluble solvents with anhydrous granular K2COs or NazSQ,. 
 
 Separation and analysis of the acetates is conducted as fol- 
 lows: ‘Take 150 grams of the water insoluble portion, thor- 
 oughly dried, and fractionate, using a simple still head. 
 
 Ist cut—107° C., ethyl acetate + other solvents. 
 
 2nd cut—107°—127° C., butyl acetate + other solvents. 
 
 erd cut—127°, amyl! acetate + other solvents. 
 
 Take a 4 or 5 gram portion of each fraction. Add 50 ce. 
 N/3 NaOH solution. Add alcohol previously distilled from 
 caustic soda to make the acetates miscible with the alkali solu- 
 
608 Analysis of Pyroxylin Coatings 
 
 tion. Reflux for about 2 hours or until saponification is 
 complete. Titrate excess NaOH with N/3 H.SQ,. 
 
 Analysis of the water insoluble portion for ketone oils, and 
 hydrocarbon solvents is conducted as follows. Ketone oil.— 
 One hundred grams of the water insoluble solvents are re- 
 fluxed for 1 hour with 40 grams of phenylhydrazine. The 
 ketones form phenylhydrazones. The mixture is then dis- 
 tilled to separate the benzol, gasoline, etc., from the phenyl- 
 
 hydrazones and excess phenylhydrazine. If gasoline is pres- — 
 
 ent the distillation must be carried to 175° C. Some decom- 
 position of the phenylhydrazones liberating NHs occurs at 
 this temperature. The distillate is washed well with water 
 and then weighed. The loss in weight represents the ketones 
 removed. 
 
 Benzol, toluol, zylol—tThe distillate consisting of alcohols, 
 acetates, benzol, toluol, xylol, and gasoline, is shaken in a 
 separatory funnel with many small portions of concentrated 
 HC! until a constant loss in volume occurs. The concen- 
 trated HCl removes the alcohols and acetates. The remain- 
 
 ing benzol, toluol, xylol, and gasoline is washed with water, — 
 
 with dilute Na.COs solution, and again with water. It is then 
 dried over anhydrous granular K2COs. The presence of gaso- 
 line is easily detected by its odor. If gasoline is not present, 
 the boiling point of the remaining solvent is taken to decide 
 its nature, i. e., whether benzol, toluol, xylol, or a mixture. 
 
 A | 
 Benzol . 2.5.5. ees 0 80° 
 Toluol 2... yi we er Dike 
 Xylol, about... ....).. 5:0 0 140° 
 
 Gasoline.—If gasoline is present, the mixture of gasoline — 
 
 and benzol is weighed and then nitrated with 3/2 times its 
 
 weight of mixed acid, 30 per cent HNOs, 55 per cent H2SQ,, | 
 
 15 per cent H.O. This nitration of the benzol is carried on in 
 - ice water lest the gasoline be acted upon. The layers of the 
 nitration mixture are separated, the oily top layer is washed 
 
 with water, dilute NazCOs solution, and again with water. It_ 
 
 is then dried over anhydrous K2CO;. The mixture of nitro- 
 
 benzol, and gasoline is then distilled to a temperature of 175°s 
 C. or until a drop of the distillate sinks in water. Gasoline 
 
Analysis of Pyroxylin Coatings 609 
 
 thus distills over separated from other solvents, and is 
 weighed. 
 
 The loss of weight of the last mixture upon nitration gives 
 the weight of the benzol. 
 
 Butyl alcohol, amy! alcohol, fusel oil—The quantity of these 
 solvents is found by difference. 
 
 95% H2SO, may be used instead of the concentrated HCl, 
 in which case the sulfuric solution may be subjected to dis- 
 tillation for the recovery of the dissolved solvents. 
 
 Examination of Solids.—The solids left from the steam dis- 
 tillation consist of pigment, nitrocotton, and resins. They are 
 dried at 60° C. weighed and then examined as shown below. 
 
 Pigment.—Pigment is not present in clear lacquers, but is 
 found in pyroxylin enamels. Five grams of the solids are 
 weighed and ashed carefully. The residue is analyzed for 
 zinc compounds, barytes, titanium oxide, and color pigments 
 as in Chapter —. 
 
 Resin.—Ten grams of the solids are extracted in a Soxlet 
 for several hours with benzol, butyl alcohol, or some other 
 solvent which will dissolve the resin but not affect the nitro- 
 cotton. ‘The solids must be crumbled and stirred frequently 
 during the extraction to insure complete removal of the resin. 
 The extract is evaporated to dryness and the resin residue 
 weighed. 
 
 Nitrocotton.—The nitrocotton is satisfactorily obtained by 
 difference. 
 
 Resin can usually be extracted from the nitrocotton almost 
 completely in the presence of pigment. An alternative method, 
 preferably if pigment be absent, is as follows. The solids 
 are dissolved in acetone, glacial acetic acid added to dissolve 
 the zine oxide pigment, if present, an excess of water added, 
 the acetone boiled off, and the precipitated cotton and resin 
 is recovered by decantation. The latter mixture is washed, 
 dried, again dissolved in acetone or ethyl acetate, benzol or 
 butyl alcohol added in excess and the active pyroxylin solvent 
 boiled off. The resin remains dissolved in the benzol or butyl 
 alcohol, but the nitrocotton is precipitated. The latter is 
 filtered off, washed well with ota or butyl alcohol, dried 
 and weighed. 
 
 The first step of the paragraph above, glacial acetic treat- 
 ment and water precipitation, is.not necessary if ZnO or acid 
 
610 Analysis of Pyroxylin Coatings 
 
 PHYSICAL PROPERTIES OF SOME LACQUER LIQUIDS 
 
 Spec. Grav. Flash Point Boiling Refractive 
 
 soluble pigment is absent. If a barytes lake is present, it 
 
 15:5/18.5° Cae ate 
 PA COCOME, (aio. kao Bie ees 0.79 —0.80 0 56 1.358 
 Acetone Oil, light....... A Rate Rea gle 0.8 -0.9 11 140-160 
 Acetotre Oi Neary co. oa a 0.9 -1,.2 160-220 
 Amy} Acétate!....ds:. 0.5 Dakin eg OOO allot 25.» 426-130 ae eees 
 Aryl Alogholc generar eee 0.825 44 121-131 1.408 
 Bento 90" kn, Oe eee 0.88 —0.89 80-120 1.50 
 Baty! Acetate... a7 coc ree 0.870 24 100-135 1.395 at 25° 
 Butyl Alcoholics we ere 0.810 35 110-118 1.396 
 Butyl Oxalate 2a 1.01 243 
 Buty!) Propionate.... acon dene 0.869 38 120-160 1.398 at 25° 
 Butyl Tartrate.004 a ee eee 1.09 203 1.446 
 Carbon Disviide:.. carne cores 1,27 =f.29 —20 46 1.620 
 Chiorolerin.hs.veis big ee 1.48 -1.49 yy 61 1.449 
 Delalin’ 2c o2.. cia necsecone tea eee 0.90 —0.915 57 185-195 1.501 
 Diacetone Alcohol..............0.2.., Ride sts 0.91 0.93 163 
 Diagaryl Putusiete caso eee 1.025 344 1.488 
 Dibuty| Phthalate <a. >. eu, ee 340 1.491 
 Ethyl Acetate, tech...) Dep asn 0.81 —0.90 —3 75— 85 1.37 
 SHthy) Alcohol. 2. raGnen os eee 0.812 18 76— 79 1.362 
 Hihivi cts ees cane a oa 0.719-0.735 35 1.356 
 Ethylene Glycol (mono ethyl ether) 0.936 133-135 1.404 at 25° 
 “Ethyl Carbonates,.t26.5. ocean 0.979 125 1.385 
 Ethyl Lactate. oo nn cee 1.038 125-159 1.411 
 Purfurgliis ss keegan eee 1.16 161 1.526 
 Fusel Oi Refined 3.) ate 0.83 43 100-133 
 Plexalens cai oe i ais beet oe 0.945 68 160 1.468 
 Methyl-Alcohol.. 7-23 inn. Ses 0.796 15 66 1332 
 Mesity! Oxide. a bnc cannon ye OU e6S 135 1.446 at 16° 
 Mineral Spivits 26 .ycnct ee ete 0.76 —0.81 24 130-230 1.41-1.44 
 Naphtha, Solvent; light...4.0.s8 0.86— 0.88 21-—23 130-170 1.5 
 Picytiienie SA avoir ee eee 0.864 100 160-179 1,487 at 25° 
 TT OtPSTM on. ae were pee soe amen es 0.975 78  . 205-209 1.535-1.55 
 Tetrilin Extreme 0.900 60 190-205 1.482 i 
 Tricresyl Phosphate. tients ty 1.498 at 25° @ 
 Potpentitie.; Siig cseneantaunteen 0.86— 0.88 32 150-180 1.465-1.474 
 de Los Riveter ity drt pneu Nght CE Sesh Sf) 0.870 7 108-112 1.490 at 25° — 
 KX vloloe tee ean eas Mette: eeheeerae cas 0.865 30 130-140 1.499 ‘ 
 
 will be found ultimately with the nitrocotton from which it — 
 
 may be separated by acetone extraction of the nitrocotton. 
 
 The nitrocotton ultimately recovered in this analytical proc- 
 ess is quite pure, but its properties will give no indication of 
 the viscosity of the cotton as it existed originally in the lac- 
 
 LP wy 
 
 gitar 22, 
 
Analysis of Pyroxylin Coatings 611 
 
 quer, nor will an analysis of its nitrogen content afford very 
 reliable information as to its original degree of nitration. 
 
 Refractive Index of Solvents. —A determination of the 
 refractive index of various fractions distilled from lacquer 
 solvents will often yield much useful information. Determi- 
 nations carried out in this laboratory upon commercial 
 samples of lacquer solvents, thinners, and plasticizers are 
 shown in Table on page 610. 
 
CHAPTER XXXVI 
 PHYSICAL TESTS ON PYROXYLIN LACQUERS 
 
 Some preliminary information can be obtained regarding 
 the usefulness of lacquers by submitting them to physical 
 tests. When they are flowed out or spun upon clean metal 
 or glass surfaces and allowed to dry, the comparative gloss, 
 hardness and tenacity of film can be gauged. If additional 
 samples are flowed out upon clean, bright tin plates (5x3 
 inches) and allowed to dry overnight, their resistance to 
 water can be determined by immersion in a tank containing 
 sufficient cold water to cover about two-thirds of their surface. 
 The panels should be allowed to remain in the water for a 
 period of eighteen hours, then removed and their condition 
 noted. They should then be placed back im the tank of water 
 and immersed for an additional period of one week, when 
 their condition should again be noted. 
 
 Two further sets of tin panels should be coated with the 
 lacquers. One set should be allowed to dry in the laboratory 
 for a period of six days at room temperature and then bent 
 over a mandril. Many lacquers will show cracking, flaking 
 and disintegration under this test. The other lacquered panel 
 referred to should be allowed to dry for a period of two hours 
 and then placed in an oven and baked at 50° C. for. twenty- 
 four hours. This should also be submitted to the bending 
 
 test over the mandril. The results of the latter test are % 
 
 generally severe. 
 
 If desired, additional panels may be coated with lacquer 
 and after drying for a definite period of time, they may be 
 tested with 50 per cent alcohol, 5 per cent aqueous alkali, 
 boiling water, or other solutions to determine their resistance 
 to these reagents. | 
 
 The tensile strength and elongation of lacquer films are 
 determined upon samples prepared by coating tin plates 6x 12 
 snches that have been amalgamated with mereury. After 
 thorough drying, the lacquer films are removed from the tin ~ 
 plates, and placed upon sheets of heavy paper. These sheets 
 are placed upon a wooden block, and with a hammer and a 
 die similar to that used for cutting rubber specimens, the 
 films are cut up into test pieces. These specimens are in the 
 
613 
 
 Physical Tests on Pyroxylin Lacquers 
 
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614 Physical Tests on Pyroxylin Lacquers 
 
 form of a dumb-bell. Each end is 26 mm. wide and 26 mm. 
 to the beginning of the taper. The central section is 49 mm. 
 
 long by 10 mm. wide. Specimens are broken upon a film- 
 
 testing machine at the end of 24 hours, 72 hours, one week, 
 and two weeks. Subsequent to two weeks, it has been found 
 that most stripped lacquers become so brittle that they can 
 no longer be used for such tests. This latter result may be 
 due to the action of the air in coming in contact with the 
 lacquer films on both sides, and rapidly affecting their 
 strength. The same lacquers, however, when applied to metal 
 surfaces and not stripped, may be very durable upon exposure 
 tests. 
 
 Roof exposure tests should always accompany physical 
 examinations in the laboratory. These tests are made by 
 using clean black iron panels 6 x 10 inches, of approximately 
 18 gauge. At the upper section of the panel the number 
 of the lacquer can be placed with a red grease marking pen- 
 cil. The lacquer is then poured over the surface of the panel, 
 and by careful manipulation allowed to flow over the entire 
 area. The panels are then drained for a period of about 
 twenty seconds and then placed in a horizontal position for 
 the drying process to continue. Smooth and fairly uniform 
 films are thus obtained. The use of the spinning device shown 
 on page — is advisable where the exposures are to be made 
 on films of any desired thickness. Panels should be placed 
 upon the roof of the laboratory at an angle of 45° facing 
 south, and should be sprayed daily with water, preferably be- 
 tween 12 and 12.30 o’clock. By this method of exposure, very 
 rapid results are obtained upon practically all lacquer coat- 
 ings. 
 
 The form used by the writer in reporting the physical 
 properties of lacquers is shown below: 
 
 Lacquer No. 1 
 
 Composition: 150 grams, (32 oz. Butyl Acetate solution; 25 
 grams Toluol; 25 grams Benzol; 25 grams Ethyl Alcohol; 25 
 grams Ester Gum Solution (50-50 in Benzol); 25 grams 
 Damar Solution (50-50 in Benzol). ; 
 
 Film Appearance: O. K. | 
 
 Cold Water Test: 18 hours, O. K. 1 Week, O. K. 
 
 Bending Test: Dried at Room Temperature. Badly chipped. 
 
Physical Tests on Pyroxylin Lacquers 615 
 
 |S EE A NT ES TE ST TS IDE LOS LEIA ELLIE. 
 EXPOSURE TESTS ON LACQUER PLASTICIZERS 
 SERIES E. 
 
 In this series the lacquers contained no resins. They were made up with 100 
 
 parts by weight of a 32 oz. Butyl Acetate Solution of 144 second viscosity 
 
 Nitrocellulose, 70 parts by weight of Toluol, and 10 parts by weight of the 
 plasticizer noted. 
 
 Panels exposed Feb. 24, 1927. 
 
 Rating on 
 April 8 May 24 General Observations 
 ; ee Rust under film in 4 weeks. Rusts 
 ee ElMeTicizer =... ss... 5 0 through in 12 weeks. 
 Be Rust under film in 4 weeks. Rusts 
 a a 4 0 through film in 5 weeks. Failed. 
 
 Entire panel covered with rust in 4 
 Benzyl Alcohol ......... 3 0 SAL aie hinted: 
 
 Rust under film in 9 weeks. Rusts 
 eee ezonte” .---.-- . through in spots after 12 weeks. 
 
 ‘ Rust under film in 4 weeks. Rusts 
 PIE VIGEsLTOLG™.......-s.. 4 3 through. in 12. weeks. 
 Film practically O. K. in 12 eweks, with 
 Butyl Phthalate ........ 10 9 but few rust spots under film. Gloss 
 excellent. 
 é : Rust under film in 4 weeks. Rust 
 "Duty! Propionate ....... 4 4 through film in 9 weeks. 
 
 Rust under film in 4 weeks. Rust 
 ie 2 s through film in spots in 12 weeks. 
 “a Rust under film in 4 weeks. Rust 
 ME eg es on ose 7 3 through film in 9 weeks. 7 
 Take ‘ Rust under film in 4 weeks. Rust 
 Semper Oil... ce eee 6 3] ro aaiiininine a eek 
 Di Film intact after 12 weeks but slight 
 
 Bee alate ...--- 2 9 rust under film. Excellent gloss. 
 i Film fairly intact in 12 weeks. Some 
 Dibutyl Phthalate ...... 9 9 rust through film in spots. Excellent 
 gloss. 
 : Rust under film in 9 weeks. Film in- 
 Diethyl Phthalate ...... 9 8 tact at end of 3 months. Excellent 
 gloss. 
 
 3 Rust under film in 4 weeks. Heavy 
 rust; through film in 8 weeks. 
 
 Mievavine ............... Rust under film in 4 weeks. Heavy 
 ES Saad . 3 rust through film in 8 weeks. 
 
 Rust under film in 4 weeks. Consider- 
 
 Ethyl Acetyl-Glycolate .. 5 
 
 Panseed Oil ............ 6 6 able rust under film at end of 12 
 weeks but film sound. 
 
 EG yh os vo ieis ow es 2 0 Film peeling off after 5 weeks. Failed. 
 
 i 0 © Rusts through film in 1 month. Failed. 
 
 ME i ke ak ee O O Film scaled off in 1 month. Failed. 
 
 Tricresyl Phosphate .... 10 7 Sound after 11 weeks but checked dur- 
 
 ing twelfth week. 
 Rust under film after 5 weeks. Con- 
 CA a 9 7 siderable rust under film at end of 
 12 weeks, but film remains sound. _ 
 ( Rust under film after 5 weeks. Con- 
 oe 9 ih siderable rust under film at end of 
 12 weeks but film sound. 
 
616 Physical Tests on Pyroxylin Lacquers 
 
 Relation of Strength and Exposure Tests —The writer 
 has attempted to correlate tensile strength and elongation 
 tests on stripped films, with exposure tests. The table below 
 presents the tensile strength and elongation of all the lacquers 
 in Series E. It would appear that in every case where fairly 
 eood resistance to weathering was noted, the films were orig- 
 inally of good tensile strength and fairly good elongation. 
 Films which showed very high tensile strength and very low 
 elongation, or very low tensile strength and high elongation, 
 as a rule, did not stand up as well in the weathering tests as 
 those previously referred to. A chart of the results is given 
 below. 
 
 PHYSICAL TESTS ON STRIPPED LACQUER FILMS AS USED IN 
 SERIES E. 
 
 -—24 Hours— —48 Hours— —1 Week— 
 Elonga- Elonga- Elonga- 
 tion Tensile tion Tensile tion Tensile 
 % Strength % Strength % Strength 
 
 No plasticizer 2.4.7, 4 see eee 0. 675 Q- 25 QO 725 
 Acetaniiig leis caus a ee ee 8S 408 S 405 7. Bao 
 Benzy! Alcohol 38 ss.cis ace ele oe 3 600 8 480 8. Bou 
 senzyl: (‘Benz0ate: 2... s5 aus eee ce 8 6) Oe 2 - 833 2 Sok 
 Butyl: Butyratey nx ea eee 4 440 4 540 2 540 
 Butyl Phthalate’ wc oye ae 6. -38zZ8 6. 308 6 344 
 sUtY].. Propionate’. . 2% va eee 2 Soe 2 480 2. 600 
 Butyl “Lartrate*.. Avs See eee 4 $98 4 885 2. 318 
 Camphor >: Gta its tae eee eee 4 350 4 400 Se Ss: 
 Camphér Gili... me ae mee ee ee 4° 580 3: 500 1 400 
 Diamyl. Phthalate. .c: 6.5 ee 3. ~ 800 3 -. 280 J "..306 
 Dibutyl “Phihainten. oven snare eee 38 384 2 240 Ou ee 
 Diethyl Phthalate: «Zeke awit eee 2° Boe Pie 8 ao Ore 
 Ethyl Acetyl Glycolate....:5....0%% 8 440 1. 420 AP 
 Hexaline. oo: ce nc eekh ba e ee 2 480 2 380 1 420 
 Linseed Olle oe eee 10 250 8. 49255 5.” 2 ve 
 Pine “OU. ee eae ee 6. "3a 3 418 a0 aU 
 Totralin. i208 cat ete ee een et 3. 560 o.4 OO 1 400 
 BV MOL cai ase oo io Sd oer er 7 460 4 420 3 470 
 Tricresyl Phosphate =... 26. sree 5 ©6400 5 gen 5 400 
 Taig Oat yee heen suet ine eae es 1. SOS 6. “300 5. 260 
 Castor: Oile vaca os ots aon eens 6 . 320 3 390 3 460 
 
 Films were stripped 1 hour after application, cut into test specimens and 
 tested at three periods. Tensile strength figures are in kilograms per square 
 centimeter. 
 
 CA a ee | 
 
 ‘ 
 ; 
 a 
 
 a. eee Se eT ee 
 
 -” 
 
Physical Tests on Pyroxylin Lacquers 617 
 
 Large cracks. 
 After Baking at 50° C. Chipped off. 
 
 Roof Exposure: 15 days, some corrosion showing at edges. 
 whole rusting from under side. 30 days, much corrosion 
 and flaking. 
 
 STRIPPED FILMS 
 Tensile strength  Hlongation 
 kg. per sq. cm. per cent 
 
 Palmetests at 24 hours ........... 73 1 
 
 Film tests at 48 hours Too brittle. 
 
 Test discontinued. 
 
 Lacquer No, 2 
 Composition: Same as No. 1, plus 20 grams Tri-Phenyl Phos- 
 phate. 
 Film Appearance: Good. 
 Cold Water Test: 18 hours, very slight bloom. 1 week, sheht 
 bloom. 
 Bending Test: Dried at Room Temperature. Badly Chipped. 
 Large cracks. 
 After Baking at 50° C: Chipped off. 
 Roof Exposure: 15 days, some corrosion at left edge, other- 
 wise O. K. 30 days, slight corrosion. Dull but fairly 
 sound, . 
 STRIPPED FILMS 
 
 Tensile strength Elongation 
 
 kg. per sq. cm. per cent 
 femeeerta at 24 hours ......... PME 56 
 Pimme tests at 48 hours ......... 60 19 
 Meets at l week ........... 100 7 
 Meme tests at 2 weeks .......... 85 7 
 
 Low Temperature Test on Lacquer Coatings. One method 
 of test which the writer has applied is to submit lacquered 
 panels, either before or after weathering, to the effects of 
 low temperature. If, for instance, the panels are taken from 
 a roof exposure test or from an accelerated ultraviolet light 
 cabinet and placed in a refrigerator having a temperature of 
 —20° C. (Frigidaire or other ice making equipment), the 
 coatings may crack or flake off if they are not sufficiently 
 distensible. If an ice making equipment is not convenient, 
 
618 Physical Tests on Pyroxylin Lacquers 
 
 there may be used a solution of solid carbon dioxide dissolved 
 in ethylene bromide or chloride. With such a mixture, 
 temperatures as low as —70° C. may be obtained. Small 
 panels may be dipped into an insulated container of the 
 solution. After immersing the panels for about one minute, 
 they may be withdrawn, allowed to assume normal tempera- 
 ture, and then examined. 
 
 Testing the Resistance of Lacquers to Bending.—In test- 
 ing varnish for what is termed ‘‘elasticity,’’ the Kauri gum re- 
 duction tests is used, a sample of varnish being made more 
 brittle by the introduction of a definite amount of ‘‘run’”’ 
 Kauri. The sample is baked upon a panel and then bent 
 over a mandril. It has been found that a somewhat similar 
 test may be applied to lacquers, the elasticity of which is 
 probably a component of the tensile strength and elongation. 
 
 For such a test this laboratory uses two solutions, one of 
 which adds to the resistance of a lacquer (addition solution), 
 while the other (reduction solution) decreases the resistance 
 of the lacquer to the bending test. Lacquers of good and poor 
 physical properties may therefore be included. 
 
 The addition solution for extending the ‘‘elasticity”’ is 
 made up of 90 parts by weight of commercial butyl acetate 
 and 10 parts by weight of tricresyl phosphate. The reduc- 
 tion solution for reducing the ‘‘elasticity’’ is made up of 1 
 part by weight of run Kauri gum and 2 parts by weight of 
 commercial butyl acetate. The same method of making the 
 run Kauri is followed as for the preparation of run Kauri 
 for varnish tests. 
 
 Butyl acetate is used in both the addition and reduction 
 solutions in preference to toluol or to other hydrocarbons 
 because many lacquers will not withstand the further addi- 
 tion of hydrocarbons without throwing the nitrocotton out 
 of solution. 
 
 In operating the tests, the non-volatile of the laequer is 
 first determined and the amount of solution to be added is 
 based upon the non-volatile. To 100 parts by weight of the 
 lacquer there is added an amount of the addition solution 
 equivalent to 10% of the non-volatile and to another 100 
 parts by weight of the lacquer there is added an amount of 
 the reduction solution equivalent to 10% of the non-volatile. 
 Thus, for instance, if a lacquer contains 40% of non-volatile 
 
Physical Tests on Pyroxylin Lacquers 619 
 
 material there will be added to 100 grams of the lacquer four 
 grams of the addition or of the reduction solution. The pan- 
 els used in this test are made of tin and are three by five 
 inches, the same type as used in the Kauri reduction test. 
 Upon the central portion of the panel is flowed a sample of 
 the lacquer to be tested that has not been reduced. On the 
 left-hand side is flowed a sample of lacquer extended with 
 the addition solution and on the right-hand side a sample of 
 the lacquer reduced with the reduction solution. The panel 
 is dried under normal conditions in the laboratory for a period 
 of thirty minutes and then placed in the oven at 50° ©. for 
 one hour. The panel is then taken out-of the oven and 
 allowed to cool to 25° C. and is then bent over a mandril 3 
 mm. in diameter. The condition of the three lacquer samples 
 upon the panel is noted. Thus, for instance, the panel of the 
 straight lacquer in the middle and the one that has been re- 
 duced with Kauri gum solution may both show cracking 
 while the one that has been extended with the tricresyl phos- 
 phate addition solution may remain in perfect condition. 
 
 Spray Test.—Lacquers should be tested to determine their 
 properties when used in a spray gun such as is employed in 
 automobile finishing plants. The amount of diluent required 
 to thin the lacquer to suitable consistency for spraying, should 
 first be determined. After the gun has been regulated and 
 the proper pressure obtained to deliver the lacquer in a mist 
 form, the test can be conducted upon large size panels (ap- 
 proximately 24 x 36 inches). The resistance of the lacquer to 
 formation of ‘‘orange peel’’ effects should be carefully noted. 
 The test can be conducted in a room where there is consider- 
 able dampness, if a determination of the ‘‘blushing’’ resistance 
 is important. Lacquers which contain a very high percentage 
 of low boiling point solvents very often show ‘‘blushing’’ or 
 whitening tendencies. The finished panel should then be 
 polished to determine whether polishing will remove the 
 ‘“‘blushing’’ and produce a smooth, uniform surface. The 
 degree of resistance to polishing should be carefully noted as 
 it will give information as to whether the right type or amount 
 of resin has been incorporated in the lacquer. 
 
 Brushing Tests on Lacquers.—Household lacquers are de- 
 signed for use with a small brush. In making a test of such 
 lacquers, it is desirable to apply them to filled wooden surfaces, 
 
620 Physical Tests on Pyroxylin Lacquers 
 
 to black iron panels, and to wooden surfaces that have previ- 
 ously been finished with varnish or paint products. Old chairs 
 finished with mahogany varnish stain form an especially good 
 type of surface upon which to test these lacquers. It is usual 
 
 to scrub the surface lightly with a rag saturated with gasoline, g 
 
 and then apply the lacquer in rapid strokes, keeping the brush 
 well filled. After finishing the object, the surface should be 
 examined to see if it is uniform in appearance and whether 
 the solvents in the lacquer have raised the underlying films of 
 paint, varnish, or other surfacing material over which the 
 lacquer has been applied. The surface should also be examined 
 for evidences of ‘‘bleeding’’ through of the organic colors 
 usually employed in the underlying wood stains. A recoating 
 test should also be made to determine whether the brushing 
 lacquer will produce a uniform, smooth coating when applied 
 in two coat work over the test surface. 
 
 Sanding Test on Lacquers and Surfacers.—Croll and Jenkins 
 of the Pittsburgh Plate Glass Co. have worked out two 
 methods of test which they have found equally satisfactory. 
 The first step in each test is to spray a measured amount of the 
 surfacer over primed or bare metal, drying the panei under 
 the conditions the surfacer is to meet and then applying the 
 sanding test as follows: | : 
 
 a. Weigh the panel, sand a given number of strokes evenly 
 distributed over the whole panel, wash off, dry and weigh 
 again. The panel should be given some time in a warm 
 place to dry after sanding in order to remove absorbed mois- 
 ture from the surfaces. Repeat and take an average. 
 
 b. Use a sanding block, about 2” by 4° and with uniform 
 pressure and plenty of water sand through to the metal count- 
 ing the number of strokes. Practice will make one quite pro- 
 ficient at giving a uniform pressure and if the test is run in 
 triplicate and an average taken a fairly accurate determina- 
 tion is obtainable. : 
 
 P. P. G. Paper Curl Test for Lacquer.—P. R. Croll has sug- 
 gested the following test as an indication as to whether the 
 proper amount of plasticizer has been added to a lacquer. 
 
 The lacquer product is sprayed on a standard 6° by 8° card 
 (Velvo, 110 lb. per ream, enameled paper has been found 
 satisfactory) and dried under the conditions the product is to 
 
 meet. Lack of plasticiezr evidences itself by a very pro- — 
 
 TE, ee 
 
Physical Tests on Pyroxylin Lacquers 621 
 
 nounced contraction of the lacquer on drying and a conse- 
 quent strong curling of the paper. This test if carefully made 
 is an excellent check upon the condition of the finished pro- 
 duct. 
 
 Testing Lacquer Enamels for Physical Properties —A 
 group representing Sub-Committee XXV of Committee D-1 
 of the A. S. T. M. has suggested the following tests to the 
 members of the Committee who are carrying on cooperative 
 work in this direction: 
 
 The samples should be kept in very tight cans and thor- 
 oughly stirred before making any determination. 
 
 Weight Per Gallon.—At least one pint of liquid, accurately 
 measured, shall be weighed at a temperature of 20° C. The 
 result shall be expressed as pounds per gallon. 
 
 Non-V olatule Matter.—Method for Varnishes (A. S. T. M. 
 standards, 1924—p. 826) shall be used except that heating 
 for one hour is sufficient. 
 
 Viscosity—F or comparative purposes, any apparatus de- 
 signed for heavy liquids is satisfactory; for comparison with 
 other laboratories the Gardner ‘‘Mobilometer’’ is suggested. 
 
 Drying Time.—F low sample and standard without thinning 
 crosswise on a clean 4° by 8” glass plate. Allow to dry ina 
 nearly vertical position. Examine for drying and hardness 
 after 15 minutes, 1 hour and 24 hours. The drying shall be 
 judged by touching or pressing the films with the finger and 
 the hardness by scratching the films with a penknife. 
 
 Fimeness.—The panel prepared for the Drying Time test 
 shall be examined by reflected light and transmitted light for 
 fineness of grinding and freedom from large particles. The 
 sample shall be equal to the standard. 
 
 Gloss——The panel prepared for the Drying Time test shall 
 be examined after 24 hours for gloss. The sample shall have 
 the same degree of gloss as the standard. 
 
 Color.—The panel prepared for the Drying Time test shall. 
 be used for the determination of color. A preliminary exami- 
 nation for color may be made after drying one hour, but the 
 final examination shall be made after 24 hours. The sample 
 shall match the standard. | 
 
 Working Test.—The methods as outlined are primarily for 
 the testing of Lacquers and Lacquer systems on steel. The 
 test panels shall be 8x12” (unless other size necessary for 
 
622 Physical Tests on Pyroxylin Lacquers 
 
 test purposes) made from ‘‘fender stock’’—a cold rolled 18 — 
 gauge sheet. 
 
 The panels should be thoroughly sanded with No. 180 sand 
 paper and finally cleaned by immersion in 90% Benzol twice, 
 allowed to air dry five minutes before applying primer coat. 
 
 Metal primers shall be applied and dried or baked accord- 
 ing to manufacturer’s directions, noting general appearance 
 and smoothness. Tests to compare primers only shall be made 
 by coating standard panels with primers to be compared, fol- 
 lowed by standard top coat lacquers. Similarly, surfacer coat 
 material shall be compared over a common primer and under 
 a common standard lacquer. 
 
 For testing a complete lacquer system, the coats shall be 
 applied as directed by the manufacturer with the drying tem- 
 perature and time elapsed between coats carefully regulated. 
 
 To assist in getting uniform spray coats the following is 
 offered: ‘‘A spray coat that is uniform and representative of 
 the material may be secured by adjusting the spray gun to 
 maximum width of fan and securing a uniform density of 
 spray; with the gun about eight inches from the surface, a 
 uniform stroke shall be used at such a speed to allow maxi- 
 mum wetness of film without sagging; each successive stroke 
 shall lap one-half of the film applied by the former stroke.” — 
 ‘After final coat is dry (at least twelve hours) one-half of the @ 
 panel shall be water sanded with No. 400 sand paper and pol- 
 ished with rotten stone and water. At least four panels shall 
 be prepared for each test, and more are preferable. 
 
 Exposure Test.—At least one panel shall be exposed out- — 
 doors on a regular exposure rack and examined at regular 
 intervals for color, gloss, ete., and compared to a similar panel 
 retained inside according to standard practice. 
 
 Adhesion.—A test panel shall be prepared for primer as — 
 described previously. A full coat of primer is applied and © 
 while still wet a piece of silk voile or bolting cloth, previously — 
 washed and ironed, is allowed to sink into the wet primer with 
 an inch or two of silk projecting from one end of the panel. 
 The primer is dried in the regular way. When dry, a safety 
 razor blade and steel straight edge are used to eut through 
 the primer and silk down to the panel in 14” parallel strips. 
 By pulling the loose ends of the silk the strips may be removed 
 from the metal one at a time. From the pull required and the — 
 character of the patches of primer left on the metal, the com- © 
 parative adhesion of any set of primers may be determined — 
 with considerable accuracy. 
 
Physical Tests on Pyroxylin Lacquers 623 
 
 Bending Test.—A one inch strip cut from the test panel 
 shall be clamped in a vise, the upper jaws of which are rounded 
 with a radius of 44”. The surface may be protected by paper 
 or cloth. The strip shall be bent over the corner of the vise 
 to an angle of 90° and the surface examined for failure. The 
 number of bends till failure occurs may be determined, if 
 desired, by straightening the strip and bending back as many 
 times as necessary. A mechanical attachment on the vise for 
 gripping the top of the strip and insuring a uniform bend is 
 desirable but not essential. 
 
 Printing Test—A test panel shall be covered with two 
 pieces of ordinary cheese cloth. On the cheese cloth shall be 
 placed a piece of felt about 3/32” thick. A definite weight of 
 about 1 lb. per square inch shall be placed on the felt. This 
 may easily be obtained by filling a quart can with white lead 
 till the desired weight is attained. The surface should be 
 examined in 24 hours, and longer, if desired. No printing 
 should occur at room temperature. 
 
 Tensile Strength and Distensibility of Film.—A_ sheet of 
 tin plate (12 x 16 inches is a convenient size, and .019 inch a 
 convenient thickness) is amalgamated with mercury. This 
 is done by pouring a few drops of mercury on the center of 
 the panel and with a piece of cotton waste, spreading the mer- 
 cury toward the edges of the panel. The smallest amount of 
 mercury required to accomplish the purpose should be used. 
 After amalgamating the panel all excess mercury should be 
 wiped off. (The mercury should be used and the amalga- 
 mated plates stored only in a well ventilated room. Opera- 
 tors should be cautioned against getting the mercury in con- 
 
 tact with food or anything by which it might be carried into 
 the mouth.) 
 
 The lacquer or lacquer enamel to be tested should be thor- 
 oughly stirred and strained. It may be either sprayed or 
 flowed, in one coat, on the amalgamated panels. If the ma- 
 terial has been flowed on, the panels should be set on end about 
 15° from the vertical so the excess material may flow off the 
 panel. This should be done in a well ventilated room or eabi- 
 het maintained at fairly uniform temperature and humidity 
 conditions. | 
 
 After allowing the films to harden for about four hours, 
 they should be stripped (brittle films might have to be stripped 
 as soon as they are sufficiently solid to be handled). The films 
 are easily removed if a spatula is run around the edges be- 
 tween the film and panel. 
 
624 Physical Tests on Pyroxylin Lacquers 
 
 The films are cut to test shapes by means of a die of suita- 
 ble dimensions (see Proceedings A. S. T. M., Volume 21, 1921, 
 Page 1111, ‘‘Stress-Strain Measurements on Films of Drying 
 Oils, Paints and Varnishes’’). The average thickness of the 
 test shape is measured most conveniently by using a stick mi- 
 crometer and taking the average of about five readings over 
 the constricted portion of the test shape. The thickness should 
 be written on each test shape, as well as some identifying num- 
 ber or letter. The test shapes that are to be tested and com- 
 pared at any certain age should be of the same thickness or 
 nearly so. They should not vary more than + 01 mm. if 
 the films are less than three weeks old (unless the film is 
 under .05 mm. thick). If the films measured have been aged 
 a longer period they may vary + .02 mm. without appreciably 
 affecting the results. These limits must be held close on 
 fresh nitrocellulose films, since the retention of volatile by 
 the films varies with the thickness of films as well as the 
 amount and nature of the volatile. 
 
 The thickness measurements being completed, the test 
 shapes should be placed in a well ventilated cabinet main- 
 tained at about 28° C. Two days before a test is desired, the 
 required number should be taken from the cabinet and placed 
 in a humidor (an ordinary dessicator with H.SO, solution of 
 proper concentration) maintained at approximately 50% rela- 
 tive humidity at 23° C. (73° F.). This relative humidity can 
 be approximated with a H.SOs—water mixture of 1.33 specific 
 gravity at 23° C. (73° F.). (See Ria Wilson—Aq. Vap. Pr. 
 and Density of H.SOx Solution as a Function of Temperature 
 —_J, Ind. Eng. Chem., Volume 13—No. 4 (1921).) While the 
 relative humidity does not affect nitrocellulose films as much 
 as it does oleo-resinous films, it may affect them to a greater 
 or lesser degree, depending on the constituents of the film. 
 
 The temperature of the room in which stress-strain meas- 
 
 ee 
 
 urements of nitrocellulose films are carried on should be kept | 
 
 at 23° C. + 2° (Approximately 69 to 76° F.), since variation 
 in temperature affects the distensible properties of these 
 films. 
 
 Enough test shapes should be provided so that checks can 
 be obtained. Five test shapes are usually sufficient, except on 
 
 an exceptionally hard and brittle film. It 1s usually the case — 
 
 that the curves coincide but differ more or less as to the ulti- © 
 mate breaking point. This is due generally to unavoidable ~ 
 
 _—-" 
 
 minute flaws along the edges of the test shape and it is, of a 
 
 course, permissible in this case to choose the curve which broke 
 
 under the greatest load. In cases where the curves of the — 
 
Physical Tests on Pyroxylin Lacquers 625 
 
 same film do not coincide, even after running a number of test 
 shapes, it is advisable to choose that curve which most nearly 
 represents the mean of all the curves. 
 
 The results may be recorded as a complete stress-strain 
 curve or as ultimate elongation and ultimate load expressed 
 in per cent elongation and load in grams (or kilograms) per 
 square centimeter. 
 
 The stress-strain apparatus used shall be sufficiently sensi- 
 tive to reveal significant differences in the softest films en- 
 countered in ordinary testing. Suitable machines are de- 
 scribed in P. M. A. Scientific Section, Circular No. 240 and 
 Broo. |. M.. Volume 21, 1921, Page 1111. 
 
 Miscellaneous Physical Tests.—Viscosity, hardness, adher- 
 ence, durability, brittleness, permeability to water, gloss, re- 
 sistance to abrasion, toxicity, contraction of film and speed 
 of drying are other physical characteristics that might be 
 determined. Many of these properties have already been 
 discussed in this and in Chapter XVIII. 
 
 Testing the Flashing of Lacquer Vapors.—In order to 
 secure some information regarding the possible danger of 
 lacquer vapors flashing in finishing shops if open flames are 
 brought into the room, a series of preliminary tests have been 
 made. In designing these tests, it was thought that lacquers 
 containing high boiling solvents would prove much safer in 
 this respect than those containing low boiling solvents. 
 
 The laequers selected for the purpose all contained 16% 
 by weight of % second viscosity nitrocellulose and 84% by 
 weight of solvent. In the first five lacquers, single solvents 
 were used in every instance. In the remaining seven lac- 
 quers, mixtures of equal parts by weight of high boiling and 
 of low boiling solvents were employed.* 
 
 The apparatus designed for this purpose is shown in Fig. A. 
 It consists of a galvanized iron chamber to which heat is sup- 
 plied by a 100-watt Mazda lamp inserted in the lower por- 
 tion of the chamber. Above the lamp is a long trough hold- 
 ing a boat containing the lacquer under test. The apparatus 
 is so arranged that the boat may be filled and pushed back 
 into the cabinet directly above the lamp. The trough extends 
 out for a distance of 36” from the heating cabinet, and every 
 inch is perforated with a small circular opening %%” in dia- 
 
 *Practical consideration makes it necessary in many instances to have some 
 low boiling solvents present in lacquers. 
 See also “A Study of the Explosive Properties of Lacquer Solvent Vapors,” 
 by E. G. Richardson and C. R. Sutton, to appear in Jour. Ind. and Eng. Chem., 
 early in 1928, 
 
"-squaajog sonbowy Jo Nogeg oapervdwoy omy Suymymsojoq 10s suywrvddy womodxy ahi 
 TOS] FHOO Ly ‘ 
 
 =< = ) 
 
 Lag ree pled Patt ad PAZ ork i, 
 
 IRSNSSSSBG 
 
 fa CBF 
 
 —w =) 
 
Physical Tests on Pyroxylin Lacquers 627 
 i eet 
 
 meter. The flame employed is about the size of a match 
 head. During the test only one opening is used, the others 
 being kept closed with corks. The top of the heating chamber 
 and the trough are covered with a thick sheet of safety wire 
 glass. 
 
 The method of operation is as follows: The temperature 
 in the chamber is first brought to equilibrium, which ranges 
 from 95° to 110° C. <A charge of ten grams of lacquer is 
 placed in the boat which is then inserted into the end of the 
 trough and pushed back into the chamber above the lamp. 
 The first test is a trial one, in which the flame is brought to 
 the hole at one minute intervals. In repeat tests the flame 
 is not applied until one minute less than the time required 
 for the trial flash has elapsed. The intervals for flame appli- 
 eation are then reduced to 15 seconds. The tests on a group 
 of lacquers should be carried out during the same day in 
 order to get closely checking results. After every test the 
 trough is swept out with a current of air. 
 
 The results of the initial tests suggested that the flash 
 point of the vapors which formed explosive mixtures with 
 air seemed to vary directly with the boiling range and indi- 
 rectly with vapor pressure of the solvent used in the lacquer. 
 Solvents of low boiling point and high vapor pressure flashed 
 in a shorter period of exposure than those of high boiling 
 point and low vapor pressure. 
 
 The tests were made at Holes Nos. 1, 20, and 30, the latter 
 hole being approximately 30 inches away from the heating 
 chamber. Some of the lacquer solvents which contained no 
 Jow boiling materials did not flash even after 30 minutes at any 
 of these holes. 
 
 Tests might also be made by using an electric spark instead 
 of an open flame. It is believed, however, that in general, 
 comparable results with those obtained in this work would 
 be shown by such elaborations. | 
 
 Testing the Latent Heat of Vaporization of Lacquer 
 Solvents. When a liquid evaporates,* there is a consequent 
 
 **“Cold Due to Evaporation—Whatever be the temperature at which a 
 vapor is produced, an absorption of heat always takes place during vaporisa- 
 tion. If. therefore. a liquid evaporates. and does not receive from without 
 a quantity of heat equal to that which is expended in producing the vapor, 
 its temperature sinks. and the cooling is greater in proportion as the evapora- 
 tion is more rapid. * * * If a little water is placed in a test-tube. which 
 is then dipped in a beaker containing some ether, and a current of air is 
 blown through the ether by means of a glass tube fitted to the nozzle of a 
 pair of bellows. the rapid evaporation of the ether very soon freezes the water 
 in the tube. Richardson's apparatus for producing local anaesthesia also 
 depends on the cold produced by the evaporation of ether. The lowness of 
 the temperature obtained depends not so much on the magnitude of the latent 
 heat of vaporisation of the liquid as on its volatility and on the rapidity of 
 the conversion.”—Ganot’s Physics. 
 
628 Physical Tests on Pyroxylin Lacquers 
 
 FIGURE 202 
 
 Apparatus used to determine loss in temperature. Dish finally used 
 one-half size of above. 
 
Physical Tests on Pyroxylin Lacquers 
 
 Isopropy| Alcohol - 
 Ethyl! Alcohol 
 
 Benzol 
 Ethy! Acetate 
 
 Butyl Acetate 
 Buty! Alcohol 
 Amy| Acetate 
 
 Toluol 
 
 Hl Mn 
 LT a a 
 Sv 
 SU A AL 
 AU 
 
 240 
 
 . 120 150 180 210 
 Time in Seconds 
 
 Curves showing loss in temperature of single solvents when treated as described above. 
 
 t ies Ou aert. 97 
 Be aus) 5921639 ‘Qunjeuedwa} ul SSsO7 
 
 FIGURE 203 
 
630 Physical Tests on Pyroxylin Lacquers 
 
 O 
 N. 
 Cc. 
 0) 
 
 o@) 
 
 O ONe) Ol a O OO 
 of 8h FB SRB oO 
 AY) 
 
 (0 
 
 aes 
 
 rd) 
 O 
 
 < 
 
 Son = 
 =) 
 
 aa) 
 
 (oe) O00 
 Ko) TAR 
 
 TIO 
 SUID R AS ERREYIE ED 
 PEL A 
 a 
 CC 
 AY 
 MUTA LAV ZL 
 
 HALL te 
 WATT 
 17 ZZdS a 
 
 B/E 
 
 when treated as described above. 
 
 PUL 
 oO Oo C 
 
 apaibhiee "SoaIbaq ‘qunyeioduia) ul "SSO} | 
 
 TIGUR 
 of Butyl Acetate-Benzol mixtures 
 
 temperature 
 
 g loss in 
 
 Curves showin 
 
Physical Tests on Pyroxylin Lacquers __ 631 
 
 reduction of temperature of the surrounding atmosphere. If 
 this reduction in temperature is very great, the dew point of 
 the atmosphere is reached, and water is precipitated. If the 
 drying of a film of nitrocellulose lacquer is too rapid, because 
 of the presence of large quantities of quick evaporating 
 solvents, the temperature is reduced, and water is deposited 
 on the film. The nitrocellulose present, being insoluble in 
 water or in solvents containing an appreciable quantity of 
 water, is thrown out of solution and appears as a cloud on 
 the surface. This is commonly known as ‘‘blushing.’’ The 
 cooling effect referred to may be noticed by coating a metal 
 plate with a rapid drying lacquer, and holding the hand on 
 the reverse side. It was thought that this cooling effect could 
 be measured in a way which would give comparative results 
 and afford information of value to lacquer manufacturers. 
 Accordingly, a study has been made at this laboratory on the 
 reduction of temperature caused by the evaporation of various 
 solvents used in the manufacture of pyroxylin lacquer coat- 
 ings. The solvents to be used were first placed in a water bath - 
 and allowed to come to a'constant temperature, namely 20° C. 
 This was done in an effort to make the conditions of the test 
 comparable. A glass dish (5 cm. in diameter and 3 em. deep) 
 was then filled with the solvent to be tested. An eight-inch 
 electric fan was placed six inches from the dish so that the 
 draft would blow directly over it. The fall in temperature 
 was determined by means of a thermometer graduated in 
 tenths of a degree C. Simultaneously with the switching on 
 of the electric fan, a stop watch was started and the results 
 _ noted at half-minute periods for a total of six minutes for 
 each sample. The results have been reported in chart form 
 below, and curves have been prepared, showing these results 
 in a more graphic manner. 
 
 Testing the Vapor Pressure of Lacquer Solvents.—The vapor 
 pressure of a liquid is the pressure of the vapor when in con- 
 tact with the liquid. When this pressure becomes equal to 
 that of the pressure of the atmosphere, the liquid may be 
 said to boil, and it then passes rapidly into a vapor. When 
 this pressure is further increased above the pressure of the 
 atmosphere, the liquid passes more rapidly into the vapor 
 state. 
 
 Vapor pressure curves are usually plotted with the tem- 
 peratures on the ordinate and the pressures on the abcissa. 
 
b> 7 
 
 632 Physical Tests on Pyroxylin Lacquers 
 
 These curves have a two-fold meaning. ‘They show not only 
 the vapor pressures of a liquid for a large number of tempera- 
 tures, but also show the temperature at which the liquid can 
 be said to boil for various pressures. For example—A cer- 
 tain liquid at 90° C. has a vapor pressure of 590 millimeters 
 
 FIGURE 205 
 
 One type of apparatus used to determine 
 vapor pressure by the statical method (a 
 new instrument for measuring vapor tension, 
 by Harold Moore,—Journal of the Society 
 of Chemical Industry, 1920, page 78-T.) 
 
Physical Tests on Pyroxylin Lacquers 633 
 
 of mercury. If the pressure of the atmosphere in a flask be 
 lowered by means of a vacuum pump to 590 mm. of mercury, 
 the liquid will boil at 90° C. 
 
 There are two methods by which the vapor pressure of a 
 liquid at a given temperature may be determined. 
 
 1. The Statical Method. 
 
 The vapor pressure of a liquid may be determined by intro- 
 ducing a small quantity of the liquid into a closed barometer 
 
 Vacuum or 
 77 Sea ia 
 PRESSURE. 
 
 FIGURE 206 
 
 One type of apparatus used to determine vapor 
 pressure by the dynamical method. 
 
634 Physical Tests on Pyroxylin Lacquers 
 et 
 tube. (Fig 205.) The space above the mereury being a vac- 
 uum, the liquid vaporizes at once. The height of mereury 
 is then measured and the difference between this and the 
 height of mereury in a barometer tube represents the vapor 
 pressure of the liquid at the temperature of the experiment. 
 Correction should be made for temperature expansion or con- 
 traction of the mercury. 
 2. The Dynamical Method. 
 
 This method depends entirely upon the determination of the 
 boiling points of a liquid at various pressures. (Fig. 206.) A 
 flask is filled with the liquid to be tested, and a thermometer 
 inserted. The flask is then attached to a reflux condenser 
 which is in turn attached to a vacuum or pressure pump. ‘The 
 vacuum or pressure is measured with a manometer gauge. 
 The temperatures at which the liquid-boils are then plotted 
 against the pressures recorded on the manometer gauge, 
 after barometric corrections have been made. 
 
 When dealing with the vapor pressures of mixtures of two 
 liquids, three cases should be considered: (1) Two non-mis- 
 cible liquids; (2) Two partially miscible mrs and (3) 
 Two infinitely miscible liquids. 
 
 To consider these more in detail. 
 
 (1) Two non-miscible liquids. Regnault stated in 1898 
 that the vapor pressure of two non-miscible liquids at a given 
 temperature is equal to the sum of the vapor pressures of 
 the two liquids at the same temperature. This rule holds 
 for mixtures in all proportions, provided that there is an 
 appreciable amount of either present. 
 
 It may be reasoned from the above that the boiling point 
 of two non-miscible liquids is that temperature at which the 
 sum of the vapor pressures of the components is equal to the 
 atmospheric pressure. For example: The atmospheric pres- 
 sure is 760 mm. From the vapor pressure curves of ‘two 
 liquids, it is found that at 80° C. the vapor pressure of one of 
 the liquids is equal to 240 mm. and that of the other lquid 
 is equal to 520 mm. 80° C, will then be the boiling point of 
 the mixture at 760 mm. (The sum of 520 and 240). 
 
 (2) Two partially miscible liquids. The vapor pressure 
 of two partially miscible liquids is less than the sum of the 
 vapor pressures of the two components, as was true in the 
 
Physical Tests on Pyroxylin Lacquers 635 
 
 FIGURE 207 
 Vapor pressure curves of several alcohols drawn from data in Physico-Chem ical Tables. 
 
 500 
 
 300 | 
 Vapor Pressure, Millimeters of Mercury 
 
 \ 
 
 a 
 Hina 
 
 ° 4 a be iy vT ap) 
 
 eco, ‘sooubaq Rey 
 
 lOO 
 
 0 
 0 
 lO 
 @) 
 
 above Case 1, but greater than either of the vapor pressures 
 taken singly. 
 
 (3) Two infinitely miscible liquids. The vapor pressures 
 of two infinitely miscible liquids is less than the sum of the 
 vapor pressure of the two components and may be either 
 greater or less than the vapor pressure of either component. 
 
636 Physical Tests on Pyroxylin Lacquers 
 
 \ BEEBE” 
 ANRC 
 AEN LEN 
 
 NMA MEAN 
 HAEREUENETABNG: BB EEL || 
 Oo 
 [oP 
 
 Been: ane » aetna 
 
 1100 
 
 Vapor Pressure, Millimeters of Mercury 
 
 900 
 
 300 
 
 FIgurE 208 
 Vapor pressure curves of several acetates drawn from data in Physico-Chemical Tables. 
 
 This vapor pressure may be calculated in a large number of 
 
 cases by use of the formula of Speyers: 
 
 MPa + (100 — m) PB 
 
 aes 100 
 
Physical Tests on Pyroxylin Lacquers 637 
 
 RE es RRR PS RSS SS A SESE RTS SP STR TE SSS RE TEE ETL | 
 
 where P is the vapor pressure of a mixture of two completely 
 miscible liquids at a given temperature. 
 
 Pa and Pp are the vapor pressures of the two components 
 at the same temperature. 
 
 M is the molecular percentage of liquid A. 
 
 There is given below vapor pressure curves of a number 
 of liquids used as lacquer solvents. ‘These curves were drawn 
 by the writer from a study of the data on pure materials 
 as appearing in Physico-Chemical Tables.—J. C. Evans— 
 Published by C. Griffin and Co., London—1902. Pages 451- 
 525. Another book giving much data on vapor pressure 1s 
 that by Sydney Young—Distillation Principles and Processes. 
 —Maemillan and Co.—1922. 
 
 Testing the Speed of Evaporation of Solvents from Lac- 
 quers. On pages 474-5 are given the results of a study of the 
 speed of evaporation of thinners from paint and varnish films 
 of the oleo-resinous type. There is presented below a some- 
 what similar study of the speed of evaporation of thinners 
 used in pyroxylin lacquer coatings. The relatively great 
 speed with which the latter solvents or thinners vaporize, 
 as compared to those used in oleo-resinous varnishes has 
 made the study a difficult one. It is felt, however, that the 
 results obtained will be of considerable aid in the design of 
 the new type coatings. Experimenters so far have paid but 
 little attention to one very important factor in lacquer coat- 
 ings, and that is the condition in which the solid constituents 
 emerge from solution to form films. The character of films 
 and their ultimate durability will depend very largely upon 
 this factor. When pyroxylin emerges from a very rapidly 
 evaporating solvent, the dew point of the moisture in the 
 atmosphere may be reached and cause premature precipita- 
 tion of the pyroxylin, producing an effect known as ‘‘blush- 
 ing.’’ Even if opaqueness of film is not shown, the continuity 
 of the surface is disturbed, and ridges of pyroxylin may be 
 seen with the aid of a hand glass or low power microscope. 
 Similarly, very rapid evaporation may cause ‘‘pin-holing,’’ 
 ‘‘ooose-fleshing,’’? ‘‘orange peel’’ effects, and similar dis- 
 turbed conditions of film that detract from the appearance 
 and physical character of the finish. A rapidly evaporating 
 solvent may be mixed with a slower one, and, thus help to 
 
638 Physical Tests on Pyroxylin Lacquers 
 
 eels | | 
 "nance SEE PL TIES Geewees post 
 
 | ectene 
 || | 
 
 180° 
 
 Br {8 
 
 160° 
 
 Lag 
 
 I20° 
 
 ic 
 N 
 IN 
 
 S) 
 o 
 ° 
 
 ees 
 
 Degrees Centigrade 
 ° 
 
 SX | 
 SY} 
 cere 
 HH 
 a 
 a 
 5 
 oS 
 ce 
 
 as 
 
 Fe 
 e 
 a 
 
 Ny 
 ss 
 q 
 
 ty 
 
 10 20 30 40 50 60) 170) GO™seGn ee 
 Percent Distilled 
 
 Figure 209 
 
 Distillation ranges of various solvents used. 
 
 overcome this trouble, but the safer method would seem to 
 he in the use of solvents whose evaporation curve would tend 
 to follow a straight line, and which at all times will act as 
 solvents for the cotton. 
 
 When a mixed solvent is used, made with a rapid evaporat- 
 ing true solvent and a substantial amount of a non-solvent 
 such as a coal tar hydrocarbon, the pyroxylin will remain in 
 solution only so long as an influencing amount of the true 
 solvent is present in the film. Later, and before dryness is 
 reached, if the non-solvent should be present in maximum 
 concentration, it may exert its non-solvent properties and 
 
Physical Tests on Pyroxylin Lacquers 
 
 UN 
 NE 
 PREC 
 CCC 
 NS 
 WRN ET 
 SINGER 
 WE WG a 
 SANG: 
 See C eae 
 
 S07. 90 100 
 
 Time in Minutes 
 
 Pre Vr 
 
 2 
 O 
 ie) 
 e) 
 ike) 
 oO 
 “wt 
 oO 
 40) 
 O 
 N 
 Hy O 
 Oo ) .e) 
 a oS OR Gee inenee ari) 2 
 jUBIoAA Ul SSO7 jUadUeq 
 
 10 
 . Determined in small friction top can covers. 
 
 FIGURE 2 
 
 solvents used alone 
 
 639 
 
640 Physical Tests on Pyroxylin Lacquers 
 
 throw the pyroxylin out of solution in a clotted form. This 
 illustrates the necessity of having present a sufficient amount 
 of true solvent at all times during the evaporation period to 
 keep the pyroxlin in true solution until films of apparent 
 dryness are produced. 
 
 Although pyroxylin films are said to dry in a few minutes’ 
 time, real complete evaporation does not take place over a 
 very long period of time, as the gel-like film acts as a sponge 
 
 to hold small amounts of solvent that go out slowly. This is” 
 
 illustrated by placing an article that has been lacquered for 
 even several days, in a warm box, when the odor of escaping 
 solvent will be noticed. This result would also indicate the 
 advisability of baking lacquers when dryness of film is an 
 important consideration to prevent surface defects of subse- 
 quently applhed coatings. 7 
 
 Rules Governing Evaporation.—There is a tendency on the 
 part of all liquids to vaporize to a greater or less extent. The 
 degree depends on conditions of temperature and external 
 pressure. The molecules in a liquid are constantly in motion, 
 vibrating back and forth. By a number of progressive vibra- 
 tions a molecule may be propelled with sufficient force and in 
 the proper direction to carry it into the atmosphere above the 
 liquid. It has then passed into the vapor state. When a 
 number of molecules vaporize, the liquid loses weight and is 
 said to be evaporating. 
 
 If, however, the liquid is in a closed container, the space 
 above the liquid will fill with vapor molecules. These are 
 also vibrating rapidly and in their motion will strike the sur- 
 face of the liquid to which on striking they will be attracted, 
 becoming a part of the liquid itself. 
 
 Consequently a liquid will evaporate in a closed space until ~ 
 
 the atmosphere above it is saturated with the vapor of the 
 
 liquid. At this point an equilibrium is set up where an equal — 
 number of molecules are passing into the liquid state to those — 
 
 passing out. Loss in weight ceases at this point until some 
 of the vapor is drawn off. A change in temperature alters 
 
 the speed of the molecules, either increasing or decreasing — 
 
 the evaporation. 
 
 From the above might be drawn four conclusions which gov- 
 ern the speed of evaporation of volatile liquids: 
 
Physical Tests on Pyroxylin Lacquers 
 
 a 
 
 lO 
 
 Keye) 
 
 Time in Minutes 
 
 | 
 an Gc CR GO8m) 
 I 
 \ELGRGE 
 
 RNA 
 
 FIGURE 211 
 
 641 
 
 Evaporation of mixtures of two solvents determined in small friction top cans, 
 
642 Physical Tests on Pyroxylin Lacquers 
 1. Temperature. An increase in temperature accelerates 
 the evaporation by increasing the vapor pressure. F 
 9. The quantity of the vapor rising from the liquid in the ~ 
 surrounding atmosphere. No evaporation could take place — 
 in an atmosphere saturated with the vapor of the liquid, and — 
 vaporization would reach a maximum in an atmosphere abso- ~ 
 lutely freed of the vapor. | 
 3. The rapidity with which the atmosphere is renewed. 
 4. The extent of surface presented to evaporation. 
 
 When nitrocellulose is mixed with the various solvents 
 used in the industry no chemical reaction takes place. 
 
 Evaporation of One Solvent—The more common volatile 
 solvents, used in the lacquer industry, were obtained for the . 
 purpose of determining as accurately as possible the differ- 
 ences between them, from the standpoint of speed of evapora- — 
 tion. Those chosen were Ethyl, Butyl, and Amyl Acetates, ~ 
 Diethyl Carbonate, Specially Denatured Alcohol (Anhydrous, — 
 Formula No. 6), Butyl Alcohol, Fusel Oil, Solvent Naphtha, . 
 Benzol, Toluol, and Furfural. 
 
 The solvents used were all commercial grades and were not — 
 redistilled to obtain specially constant boiling ranges. Dis-— 
 tillation ranges were determined for all these solvents using — 
 the method outlined in the Federal Specifications for Turpen- — 
 tine. The thermometer used was a distillation thermometer 
 with a range from 0° C. to 490° C. The results are shown 
 in Fig. 209. 
 
 A number of methods to determine the speed of evaporation 
 were at first experimented with, but none of them gave the ~ 
 same relative results for repeat determinations. This was — 
 largely due to variations in temperature and in the movement 
 of air in the laboratory. The first attempts were made on ~ 
 relatively large quantities of the solvents, each being run at — 
 a different time, and none of the samples allowed to go to dry- — 
 ness. A shallow pan was filled with the solvent and weighed ~ 
 at intervals and the evaporation plotted together with the — 
 time. It was proven at once that this method was inaccurate, 
 as two samples of the same material run one immediately 
 after the other failed to give concordant results. - 
 
 It was thought that the atmosphere above the pan became > 
 more or less saturated with the vapor of the liquid, thus alter-— 
 ing the vaporization. Accordingly a stream of air was passed 
 
Physical Tests on Pyroxylin Lacquers 
 
 20 30 40 50 60 7 80 90 
 
 lO 
 
 One @) 
 Oy wee ae 
 
 yUBIan Ul SSO] YUddUE4q 
 
 Time in Minutes 
 
 FIGURE 212 
 
 Evaporation of solvents from 16 oz. nitrocellulose solutions. 
 
 643 
 
 Determined in small friction top can covers. 
 
644 Physical Tests on Pyroxylin Lacquers 
 
 about two inches above the surface of the pan. It was found 
 that by varying this air stream the results could be made to 
 vary within very wide limits. Concordant results were not 
 obtained with this method. ; 
 
 The method finally decided upon made no allowances for 
 either temperature or movement of air in the room. One 
 
 gram (+.005) of the solvent was weighed from a burette into 2 
 
 a friction top can cover (diameter 5 em.), the material being 
 flowed over the bottom and the time noted. The sample was 
 then reweighed at intervals until it had completely vaporized. 
 All the samples were run under exactly the same conditions 
 and at the same time. The results obtained are shown in Fig. 
 
 210. Tf these same solvents were run in the same manner at © 
 another time different results would be obtained, but the — 
 
 curves would maintain their same relative positions with re- 
 spect to each other. This was determined by actual test. 
 
 It will be noticed that all the lines on the chart are nearly 
 straight, which probably indicates the purity of the solvents 
 
 and their freedom from slow vaporizing residues. As will — 
 
 be seen in Fig. 211, which represents mixtures of two solvents, 
 
 the curves are not straight lines except in the cases of the pure ~ 
 
 solvents themselves. 
 
 Evaporation of Mixtures of Two Solvents——Two solvents © 
 
 were chosen, one evaporating very rapidly and the other very 
 slowly. Various proportions were made by volume. 
 
 1s Se ee ee 100% Ethyl Acetate 
 9 75% Ethyl Acetate 
 Ss OE he a 95% Butyl Alcohol 
 3 50% Ethyl Acetate 
 ei ES a eee 50% Butyl Alcohel 
 4 25% Ethyl Acetate 
 Re ee hi 75% Butyl Alcohol 
 Boo ey Oo ee 100% Butyl Alcohol 
 
 These five samples were run in exactly the same manner as — 
 the pure solvents used above. The results of another test on — 
 the same samples would show the same relative positions of — 
 
 the curves and their general direction will be the same. The 
 results are shown in Fig. 211. 
 
 7 ¢ 
 2 anh: ee : P 
 ee pen SS Nee v . 
 
Physical Tests on Pyroxylin Lacquers 645 
 
 Determined in small 
 
 Ke) 
 
 QD as 
 es 
 OWL 
 ON 
 JONG fF 
 
 ie 
 ee 
 
 ~—y.)§.].|, SRS 
 {Seas 
 O Oo © Ox = 
 Pee Oo in fe 
 
 Oo O 
 ae we 
 
 lO 20 30 40 50 60 70 80 90 100 
 
 aporation of Butyl Acetate from solutions of various percentages of nitrocellulose. 
 
 Ey 
 
 yyBbiayy ul SSO7 YUaddaY 
 
646 Physical Tests on Pyroxylin Lacquers 
 
 As will be noticed the curves for pure ethyl acetate and 
 pure butyl alcohol are very nearly straight lines, while those 
 of the mixtures are bent, showing very clearly the presence 
 of two or more liquids which vaporize at different speeds. In 
 each case the mixture loses a large proportion of its ethyl ace- 
 tate, then loses a mixture of the two solvents at a medium rate 
 of vaporization and finally loses the butyl alcohol at practi- 
 cally the same speed as butyl alcohol vaporizes alone. 
 
 The mixture of 75% Ethyl Acetate and 25% Butyl Alcohol 
 for example, apparently loses about 45% of the 75% LHthyl 
 Acetate present. The remaining 35% apparently evaporates 
 with probably about 10% of the Butyl Alcohol. This leaves 
 about 15% Butyl Alcohol to vaporize practically by itself as 
 the curve from that point corresponds very closely to that of 
 Butyl Alcohol. 
 
 The distillation range was determined for the mixture of 
 75% Ethyl Acetate and 25% Butyl Alcohol, and is shown in — 
 Fig. 209, together with the distillation ranges of the various © 
 solvents used. , 
 
 Various Solvents Mixed With Nitrocellulose-—Solutions 
 were made up on the basis of 16 ounces of dry nitrocellulose 
 in one gallon of solvent.* No allowance was made for ‘‘swell- 
 ing.’? The solvents used were Ethyl, Butyl and Amyl Ace-— 
 tates, Diethyl Carbonate, Furfural and specially Denatured 
 Aleohol (Alcohol Soluble Nitrocellulose was used in this last 
 ease while regular solvent nitrocellulose was used in all other 
 solutions). The remainder of the solvents, for which the — 
 speed of evaporation was determined above, were not used 
 in these experiments as nitrocellulose is but sparingly soluble — 
 in them. 3 
 
 Several methods to determine the speed of evaporation — 
 
 were tried before satisfactory results were obtained. In this 
 work weighing bottles fitted with corks in which a brush was : 
 fastened were first used. The bottle was weighed, a sample 
 transferred with the brush to a thin glass plate and the bottle ~ 
 reweighed to determine the weight of sample taken. The glass — 
 plate on which the sample was brushed was weighed at varl- 
 ous intervals, timed by a stop watch, until a constant weight — 
 was obtained, indicating that all the volatile matter had evap- — 
 
 *The nitrocellulose used in these tests was received wet down with 30% z 
 
 alcohol. In other words, 100 lbs. of the material contained 30 Ibs. of alcohol. : 
 
Physical Tests on Pyroxylin Lacquers 647 
 
 orated. Concordant results were not obtained with this meth- 
 od due to the fact that a constant thickness of film could not 
 be obtained, approximately the same weight of film being 
 spread in a different thickness each time, presenting a vary- 
 ing surface to evaporation. 
 
 The method finally decided upon was the one used in the 
 work on solvents alone as described before on page 644. 
 One gram (=+.005) was weighed from a burette into a small 
 friction top can cover, (diameter 5 cm.) and the sample spread 
 equally over the surface. The pan was reweighed at intervals 
 until a constant weight was obtained indicating that all the 
 volatile matter had evaporated. The results obtained are 
 shown in Fig. 212. These curves are thought to be compara- 
 tive, but should not be compared with curves which are shown 
 in other plates in this chapter. 
 
 Various Quantities of Nitrocellulose to-One Solvent.—Five 
 solutions were made up by adding 1, 3, 5, 7, and 9 grams of 
 nitrocellulose to 25 cc. of Butyl Acetate. These solutions rep- 
 resent 3.74, 11.23, 18.70, 25.18, and 33.66 ounces of dry nitro- 
 cellulose to one gallon solvent, respectively. The solutions 
 were run in the same manner as before; that is, weighing one 
 gram from a burette and allowing it to evaporate, weighing 
 at intervals until dry. The results are shown in Fig. 213. 
 
 It will be noticed from the chart that in each case approxi- 
 mately 50% of the sample evaporates before the lines diverge 
 at all. At this point they spread fan shape and each goes to 
 a point which is determined by the particular percentage of 
 non-volatile present in the sample. 
 
 After the solvent had evaporated, the average thickness of 
 the film was determined. The results obtained as compared 
 to the thickness of Oil Varnish films made from varnishes of 
 different volatile content is shown below: 
 
 Grams Ounces 
 
 wet Nitro- dry Nitro- Thickness 
 
 cellulose cellulose of Lacquer Viscosity (Gardner-Holdt) 
 
 in 25 c.C. to 1 gal. Films 
 mn 3.74 20u Two bubbles faster than A 
 3 1t:23 32u One bubble faster than A 
 5 18.70 5d B 
 ‘< 25.18 60u G 
 9 33.66 TT K 
 
648 
 
 Non-volatile 
 40% .. 
 45%... 
 50% .. 
 55% .. 
 60% .. 
 
 Thickness of Varnish Films ie DE Bohai 
 Viscosity Constant K (Gardner-Holdt) 2.75 Poises — ss 
 
 - 
 
 “ 
 
 Physical Tests on Pyroxylin Lacquers 
 
 ae 
 
CHAPTER XXXVII 
 MISCELLANEOUS METHODS OF TESTING MATERIALS 
 
 There are presented below some miscellaneous methods of 
 test which have been developed at this laboratory and which 
 have proved of general use in evaluating raw materials or for 
 studying their properties: 
 
 Testing the Color Number of Dry Pigments.—On examin- 
 ing samples of prepared paints that have been stored for long 
 
 FIGURE 214 
 
 Water solution of methylene blue added to lithopone in bottle on left and to 
 china clay in bottle on right. After shaking and standing the china clay has 
 completely absorbed the blue color, producing a blue lake pigment which 
 subsides to the bottom and leaves the colorless water above, the lithopone has 
 shown but little absorption and is still white. 
 
 periods of time, the oil floating on the surface will often 
 appear to be extremely pale in color as compared to the rather 
 dark amber color of the raw linseed oil used in grinding. 
 
650 Miscellaneous Chemical Tests 
 
 Apparently the foots and some of the coloring matter in the 
 oil are adsorbed by the pigment particles, thus allowing the 
 oil to become very clear and of unusually light color. As a 
 result of such observations, the writer has assumed that pig- 
 ments will show varying degrees of adsorptivity. In order to 
 determine the possibilities in this direction, a few dyestuffs 
 were experimented with. In dilute aqueous solution, they 
 were shaken with a number of pigments. Almost immediate 
 discoloration of these dye solutions was observed when in 
 contact with some pigments, and practically no change with 
 others. The results seemed so interesting that it was thought 
 advisable to develop a quantitive method of determining the 
 adsorptive properties of various pigments, and for this pur- 
 pose there was selected a dyestuff which could be titrated 
 quatitatively, namely Methylene Blue O concentrated. While 
 it is possible that Indigotine and some other dyestuffs might 
 be fully as useful in this connection, it was decided to use the 
 methylene blue because of the very sharp changes in color 
 value, which are observed upon titration. The method of 
 running the test is as follows: | 
 
 Method of Test—Twenty grams of dry pigment is placed 
 in a half-pint clear glass bottle, and 150 ec. of a standard 
 aqueous dye solution is added. (This dye solution is made by 
 dissolving 0.25 grams of Methylene Blue in one liter of dis- 
 tilled water.) The bottles containing the pigment and dye 
 solution are then capped and vigorously shaken for two — 
 minutes every day for a period of one week. They are then 
 allowed to stand for any desired period of time, and the dye 
 content of the solutions determined by titrating an aliquot 
 portion of 50 ce. of the clear liquid with a 0.01N solution of 
 titanous chloride. The difference between a blank titration 
 on a portion of the standard dye solution and the pigment 
 sample titration, multiplied by the grams of dyestuff which 
 each cubic centimeter of titanous chloride is equivalent to, 
 gives the amount of dye adsorbed by the pigment. This factor 
 might be termed the Color Number, and is expressed as the 
 milligrams of dye adsorbed per gram of pigment. 
 
 Preparation of Solution—The method for the preparation 
 of the 0.01N titanous chloride solution is similar to that used 
 
Miscellaneous Chemical Tests 651 
 
 by English * for estimating the strength of dyestuffs, and is 
 as follows: Titanous chloride usually comes upon the market 
 in a 20 per cent aqueous solution; 33.5 ce. of this solution and 
 70 ee. of concentrated Bdrochloric acid (specific gravity 1.19) 
 are boiled together for about a minute. After cooling in an 
 atmosphere of carbon dioxide or hydrogen, this solution is 
 added to 5 liters of distilled water in a large bottle. This dis- 
 tilled water must be free from dissolved oxygen, and should 
 first be boiled 20 or 30 minutes and cooled in an atmosphere 
 of carbon dioxide or hydrogen before placing in the bottle. 
 After the titanous chloride acid solution is added to the dis- 
 tilled water, thorough mixing is obtained by passing a rapid 
 stream of ehon dioxide or hydrogen through the solution. 
 
 Titration.—This titanous chloride solution is used in the 
 following manner: Fifty ce. of clear dye solution is removed 
 from above the settled pigment in the bottle, filtered if neces- 
 sary, and transferred with a pipette to an Erlenmeyer flask. 
 Twenty-five ce. of a 25 per cent aqueous solution (75 water, 
 95 sodium tartrate) of sodium tartrate is added. The mixture 
 is boiled for three minutes, and titrated while hot with the 
 titanous chloride solution, in an atmosphere of carbon dioxide, 
 to the last distinct color change. 
 
 Lakes Formed.—With certain pigments, the rapidity of 
 adsorption in the above test was so great that within a few 
 minutes after the addition of the Rega solution and shaking, 
 the color was entirely discharged by adsorption, and several 
 subsequent additions of the dyestuff solution were necessary in 
 order to show any permanent color. With such pigments, the 
 plan of procedure was to reduce the amount of pigment used 
 for test, using 10 grams, 5 grams, 1 gram, or lower quantities, 
 with the same amount, namely, 150 ce. of the standard color 
 ‘solution. It was interesting in these experiments to note the 
 lakes that were formed with various pigments. Thus, for 
 instance, certain white pigments were practically unattacked 
 by the solution of blue dyestuff, and settled out to the bottom 
 of the bottle to a white mass, with the clear methylene blue 
 solution above. Other white pigments rapidly adsorbed the 
 dyestuff and settled out to the bottom of the bottle in the form 
 of a blue mass, leaving colorless water above. 
 
 *Analysis of Aromatic Nitro-Compounds. F. L. English, J. Ind. Eng. 
 Chem., Oct., 1920, p. 994. 
 
652 Miscellaneous Chemical Tests 
 
 In order to determine whether there is any relation between 
 color adsorption and oil adsorption, the pigments which were 
 
 included in the tests were run for the latter physical property 
 
 and a summary of the results is given below. In the Chart 
 the color number is the milligrams of dry methylene blue dye- 
 stuff adsorbed by 1 gram of pigment. The acid number is the 
 milligrams of sulphuric acid per gram of pigment. The alkali 
 number is the milligrams of potassium hydroxide per gram 
 of pigment. The oil absorption is the grams of oil required 
 per 100 grams of pigment. This was deterinmed by rubbing 
 the pigment on a ground glass plate with a spatula, adding the 
 oil drop by drop until the pigment assumed a coherent state 
 and slightly smeared the glass. 
 
 In running the acidity or alkalinity, tenth normal solutions 
 of sulphuric acid or caustic potash were used with all pigments 
 except with Nos. 1 to 10. With these pigments, a fiftieth nor- 
 mal alkali or acid solution was used, but unfortunately only 
 ten grams of each pigment were left from the reserve stock 
 for these tests, and therefore the information presented in 
 our Chart does not entirely agree with the acid number given 
 by the manufacturers of these pigments who generally use 50 
 grams of pigment for determining alkalinity or acidity. The 
 information submitted by the manufacturers was to the effect 
 that samples Nos. 2, 4, 7 and 10 are aproximately neutral; 
 samples Nos. 1, 5, 8 and 9 are slightly alkaline; while samples 
 Nos. 3 and 6 are more strongly alkaline. 
 
 TABLE 72 
 
 Color Number of Pigments 
 
 Color Acid Alkali Oul 
 No. Pigment Nos. Noroe he Absorption 
 
 1 No. 1 Lithopone iba ee 1.09 Neutral 9.9 
 
 2 No, 2 Lithopone......tuinee a eee 0.70 Neutral 10.2 
 
 3. No. 3 Lithopontic oan 0.81 0.23 tha 
 
 4 No, 4 Lithopone. 7.20 2. hie ee 0.682 0 11.9 
 Slight 
 
 5. No. 5 Lithopone....c aie ee 0.99 Alkaline 13.6 
 ; Slight 
 
 6G) No. 6 Lithoponé. 71-0 ee 0.47 Alkaline 14.9 
 
 7 No.7 Lathoponés, 4 2 ee 0.89 Neutral is.7 
 
 & No. 8 Lithopote nis 7o ee ee i Neutral 16.2 
 
 9 «No. 9 Lathopone \Auyi cous ee eee 1.04 Neutral ioe 
 10° Noo 40 Lithopone:c3 eee ae eee iS Neutral 17.8 
 11. Biano Fixe 3s y50.. eee ee oe 0.68 0.04 24.5 
 12 - Agbestine.vGgewjcis ee Ree ee ee 18.6 0.04 35.0 
 
 a 
 ei 
 524 
 ee 
 
 ye 
 
 ee 
 
Miscellaneous Chemical Tests 653 
 
 Color Acid Alka Oil 
 No. Pigment No. No. No. Absorption 
 
 MRE GOVY HIELO sie ccts sarc caecsccccdsccesctsvcssecesceccn on 3.43 — 19.5 
 Serer ea ons sin ve sci acasafscgeredizcasisanens 12-5 0.04 50;5 
 RICE CAV SUIT 6... seco ces gececsdgusanecsesnnee 0.94 ———— a es 
 16 Leaded Zinc (5% Lead sulphate).....0.000000....... 125 —__—_— 1955 
 1h, A obec dun sao cess sees cgauersistececsyes 13.8 0.95 32.0 
 UE ATION il one ce cd ccscacseivldecccegeseecco ses P2324 0.06 3tt3 
 MEUPITIETE LAT ATIOK io ices ocescecccevcessectclicersecsscenreeee 0.70 —_—_—_—— 18.7 
 Nooo ce gacccac cose sesensdosscstanpaseacedessnens 0555) <0, 12 | 16.8 
 eee re 1 Peat OXI 2... <.<cccsecsessccccceeescceeceees 1.85 ——__—_— 56.9 
 22 Leaded Zinc (65% Lead Sulphate)................ £28 0:13 1321 
 meee yy nite Lead (Electrolytic)...............ccccceccsecseeees 0.47 0.06 11.8 
 24 Medium Chrome Green 16% on Barytes- 
 
 i ONES on 6.96 pe 14.9 
 25 Light Acetate Green on Barytes Base.......... 1.82 ———— 10.2 
 26 Light Grinding Green. 25% on Barytes- 
 
 EAS aay feck io Lvs ectresasnes: Mine Beto 3.69 —__—_—— 15.9 
 27 Chrome Green. 20% on Silica Base............ Nar —_———— 17.8 
 soon lst O54 Tack G0 Seale 1.82 ——— —— 
 eames yr eritie, F. ML coc ccce se secsscseccsccseseeeeeecees 37.2 0.06 — 
 UG PC TOLCCT C}CHLE. .... ci cccccesc-ceceecsssesccveeseoceses 3.62 —_— 1S 
 TS eT 0 Sl Os a 0.00 ———— 39.5 
 62 italian Raw Sienna. 54% Iron Oxide.......... 34.3 —_———— 48.5 
 Go Herrite Yellow. Dark Orange..............0..00.... O70 — 0.54 61.0 
 eae, Lemon Chrome Yellow......................... O50! 0:12 16.8 
 SVS Coho) St 7 rr Lice —_— 49.0 
 36 Turkey Raw Umber. 46% Iron Oxide........ 375 — 49.5 
 37  Prince’s Mineral. 34% Iron Oxide.............. Lt Se 24.0 
 38 P. Metallic Brown. 61% Iron Oxide............ 1.22 ———— 34.0 
 yh os Lassies vesvucSsainsesevseseonnes 0.67 0.11 10.7 
 eer erurore Oxide, 82% Iron Oxide................4: 1.38 ———— 10.2 
 41 No. 59 Indian Red L. N. 96% Iron Oxide 0.23 ee 20.1 
 42 No. 50 Canadian Oxide. 91.5% Iron Oxide.. 1.83 eee 28.5 
 43 Maroon, 10% Alphanaphthylamine on 
 
 Barytes-W hiting Base: ..........0.....ccccccseers —_— 23:8 
 44 Alizarine Lake................. Tg SP aa erga 33.6 — 
 45 No. 3439 Tuscan Red L. N. 26% Iron 
 
 ye ays  iahincs's Sadie uiapeonedene oie 3.70 16.8 
 46 American Vermilion. Basic Chromate of 
 
 Ne hy i cnieisevsushatucd thacsguaaca 0.28  ————— 131 
 47 Deep Para Red—10% Para on Barytes- 
 
 TEs en a oe — 18.7 
 48 Deep Para Red—20% Para on Barytes- 
 
 Ee 13.4 a 40.5 
 MM OES OC oie ccsaseies sesessceeccesssnsstscesseensvicesens 1.88 0.11 14.6 
 Boeeeen English Vermilion........0..)..... seca 0.76 ——— 12.9 
 
 51 Light Para Red—10% Para on Barytes- 
 
 USE Sa a 1.88 O14 18.7 
 52 Scarlet Lake—34% Xylidine on Blanc 
 RE gehen Sea cag urtats oj-abig ue A nee —_ a5 
 
 53 Methyl Red. 2% Lithol on Orange Mineral ly Ae) 0.04 10.7 
 
654 Miscellaneous Chemical Tests 
 a ——————— 
 
 Color Acid Alkali Ol 
 
 No. Pigment No. No. No. Absorption 
 54 Orange Minerali.n.v.cieniiagn tomers 0.79 ——— 134 
 55. Cherry Red icc. 3: atone ses ea eee 3A 8.2 
 56 C.P Orange Chrome Yellow... 24. 1.08 0.09 17.8 
 57 Magnetic Red Oxide. Prectpitated.............. 1.36 0.24 33:5 
 SR Prussian Blue. ioc. et ae ones ae 1.80 0.66 100.5 
 590 Drop Black Xo Roe nnce oe ei ee 36.9 0.76 49.5 
 60 No. 73 Drop Black cc rece oe eee 36.6 — 1329 
 61 Mexican Graphite. 52% Carbon................. 18.0 0.06 36.0 
 62 B. V.; Lampolack.....0 os cnbgpuneme eee 14.7 0.12 — 
 63. Carbon Blacit snc Gc. eee 69.6 0.06 46.0 
 64... Carbon Blacks (180). ..2c coger 187.5 ———— 186.6 
 65 Black Iron Oxide. Precipitated.................-.: L083 49.5 
 66 Red Oxide of Mercury...2 2 0.97. . 048 8.8 
 67 Antimony Oxide.:..03.5. ieee eee 0.36.2 26.5 
 68 Fuller’s Barth. ..c.s55¢-4e-.0 ogee 294.0 ——_——— 108.4 
 69 Lithopone S1926..........0. cece tes 102 32.0 
 70. Zine Oxide XX 51926005 ec ee — 0.66 29.0 
 71 Zine Sulphide-S1926.5o.5 cc har ee 1.525236 21:5 
 72 High Strength Lithopone $1926..............04 2.17 ——— 16.8 | 
 
 Under Acidity a long dash is shown wherever pigments required only one drop of 
 N/10 Alkali to show permanent red color with Phenolphthalein. 
 
 Testing the Wetting Properties of Pigments With Different 
 
 Liquids.—A considerable amount of work has been done in 
 
 this laboratory in determining the wetting properties of vari- 
 ous liquids upon pigments.* In this work, large test tubes 
 were used, into which were placed 10 ec. of each of two differ- 
 ent types of immiscible liquids. 
 
 Into each test tube was then placed an amount of dry pig- 
 ment equivalent to the size of the head of a match stick. As 
 the pigment dropped through the upper layer of liquid, its 
 speed decreased when it reached the line separating the two 
 liquids. In many instances reactions would occur at that line, 
 which would subsequently allow the pigment to either drop 
 through to the bottom liquid or remain suspended at the inter- 
 face. Upon shaking the tubes for a few seconds, an emulsion- 
 like mass would be formed, which would gradually separate 
 into two layers. The pigment would either go into one layer 
 or would be suspended at the interface. Very rapid move- 
 ment of the temporary emulsified particles would take place 
 for several seconds, a miniature battle being waged between 
 the liquids to determine which would wet the solid. That the 
 
 *See Scien. Sec. Circ. No. 295. 
 
Miscellaneous Chemical Tests 655 
 
 result of the battle would not be due entirely to the gravity 
 of the materials is indicated by the fact that pigments of prac- 
 tically the same gravity might be found to finally rest at the 
 bottom of the lower liquid or in the upper liquid, according to 
 the surface attractions presented. After these experiments 
 were made, it was found that some similar work was done by 
 Hoffmann with a number of dry substances but with liquids 
 that are applied less to the paint and varnish industry than 
 those experimented with in the present writer’s work. Hoff- 
 mann’s experiments are described on page 102 of Bancroft’s 
 ‘Applied Colloid Chemistry.’’ He found, for instance, that if 
 powdered glass is treated with water and then shaken with 
 kerosene, the glass goes into the water phase. If, however, 
 the dry glass powder is first allowed to stand for a long time 
 with kerosene, some of the glass powder will remain in the 
 interface, but vigorous shaking will cause the water to dis- 
 place the kerosene. 
 
 Some of the results obtained are pictured and reported 
 below. 
 
 It is conceivable that processes might be developed, where- 
 by pulp colors coming from the washing tanks, and probably 
 relatively free from adsorbed air particles, might be wetted 
 with much greater ease than dry particles, the surface of 
 which had absorbed air or gases and which would then 
 be resistant to wetting with oil. Such pulp colors, if 
 properly agitated with oil under certain conditions, 
 possibly in the presence of added chemicals * to lower the 
 surface tension effects, might readily be incorporated with 
 the oil. Experiments in this direction apparently offer prom- 
 ise. The fineness of the pigment, the amount used, and the 
 acid value and temperature of the liquids are factors which 
 would probably exert influences in such phenomena. 
 
 PIGMENTS ADDED TO TUBES CONTAINING TOLUOL 
 AND WATER 
 
 Upon adding pigments, all settled gradually in snowflake fashion to the 
 bottom of the tubes, with the exception of Nos. 10, 14, 15, 16, 17, and 18, 
 which remained at the interface. After shaking, the pigments remained 
 Suspended in the layers indicated by X. 
 
 *Aqueous soap solutions are suggested. 
 
656 Miscellaneous Chemical Tests 
 
 Upper Layer Lower Layer 
 
 Toluol Water 
 1 Antimony Oxides. 0327) ee xX 
 9° “Zane Oxide So tae xX 
 3% LAtBODOREG Gd... nd te yeh xX 
 4 Leaded Zinc (5% Lead)...:....0.... >, 
 5. Basie Lead Sulfate co xX 
 6 Basic Lead Carbonate. ..20..00% 4 
 i. Baran Trane Sos = 
 By Calerwnr Pitan rt eee xX 
 Rar Pere: Lao. oh eaee ree ake »4 
 10. Magnesium iSil-cate.7. a x 
 t1°) Calsidiy Carbonate.3 244.2 x 
 12 + ‘Red -Lead 2 ae ae x 
 13.“ adien Reda on ee eae ».4 
 14°: Toluidine Toners. Gaieceee ».4 
 15. Raw Sienties...< oii eee xX 
 16. “Raw Umber4-2550 eae Some at interface xX 
 17 Graphite ck 2 2 ee At interface 
 18. -- Carbon Blacks Us ce eee x 
 19. “Fuller's Barth: hoa eee “6 
 20 Light Green 25% on Barytes- 
 Clay -Baseccae ie ee Some at interface xX 
 
 PIGMENTS ADDED TO TUBES CONTAINING A MIXTURE OF 
 MINERAL SPIRITS AND WATER 
 Upon adding pigments, the general tendency was for them to remain 
 largely at the interface, with slight amounts settling slowly in snowflake 
 form to the bottom. Pigments Nos. 2, 5, 11, 14, 16, 17, and 18 remained 
 entirely at the interface. Upon shaking, the pigment remained suspended 
 in the layer indicated by X. 
 
 Upper Layer Lower Layer 
 Mineral Spirits Water 
 1 > Antimony Oxides47.4 5 ies xX 
 2, dine Uxede. 3.7.93. 70h Se ere x 
 3 “Lathopone. with. cpaaeeerer ear uee xX 
 4 Leaded Zinc (5% Lead)............ At interface 
 5.” Baste bead: Sultatex. ie sacseeee At interface 
 6 Basic Lead Carbonate. » 
 7 Barium tangs) eee At interface 
 8. Calerum Titesiox piesa xX 
 9 -- Pigre Pie. 0n cv ie eee xX 
 10 Magnesium Sulitate. nos ces. xX 
 11 .. Calcium Carbonate nie ee = 
 12° Red Dead Ae se eee x 
 13 “Indian Regist oe ee At interface 
 14 » Toluitine: Toner. 3 3 ee At interface 
 15: Raw Sienna oe eer x 
 16 Raw Umber 25.450 4 
 17: Graptite o223e.. 2 ele xX 
 18 = Carbon Blick .cnae i ee At interface 
 19° Puller’s Earth... iota At interface 
 
 20 Light Green 25% on Barytes- 
 Clay Base: 25.2 ie ee At interface 
 
Miscellaneous Chemical Tests ) 657 
 
 AYA | 
 
 > fe 
 e 
 ¥ 
 
 LR a i: %, Sy ue 
 sd ’ 
 
 ~~ > 4 
 m3 
 
 a 
 
 ae 
 nS 
 
 as 
 
 ¥. 
 
 a i, 
 
 DAE. 
 
 : 3 
 a. iY ca ak 
 
 283° 
 Cle 
 oa ¢ 
 put 
 Oak 
 5 
 24 
 ca 
 = 
 pos 
 ¢€ 
 Ones 
 So 
 ¢et 
 a 
 ae) 
 eG) 
 2 Ad OR) 
 San) 
 
 Ge 
 
 232 #8 
 3 a xX 
 Cod” nen 5 
 417 5: 
 — PO 
 Seni > 
 Det 
 © 3 
 o = 
 ote 8 
 rho npriace 
 
 sya 
 
 2 
 
 » tag Mins 
 ge 9 
 A) Uk 
 
 : a a 
 Shes x 
 
 . \ ° 
 S 
 : bay 
 is 
 
 Fig. 215 : Fig. 216 
 
 Fig. 215.—Before Shaking: Upper layer toluol, lower layer water. Lithopone 
 pigment rests at interface and is gradually dropping like snow- 
 flakes into lower layer. 
 
 Fig. 216.—Before Shaking: Upper layer linseed oil, lower layer water. Litho- 
 pone pigment dropped rapidly in spherical shape to bottom layer and carried 
 with it a globule of linseed oil which is endeavoring to become detached and 
 float back to surface. A bubble of air is occluded at the apex of the oil. 
 
 PIGMENTS ADDED TO TUBES CONTAINING WATER AND 
 LINSEED OIL LAYERS 
 
 Upon adding pigments, they suspended to some extent throughout the 
 upper oil layer, then gradually started to diffuse through the lower water 
 layer. Pigments 13, 15, and 18 remained in the upper oil layer for a very 
 Substantial period of time before diffusing slowly into the latter layer. Upon 
 Shaking, the pigment remained suspended in the layer indicated by X. 
 
 Se ee a ee eee Te 
 
 Upper Layer Lower Layer 
 Linseed Oil Water 
 Meeemony Oxide........................ Xx 
 MUG Xx 
 MP EMODONG. oc... secs Very cloudy Xx 
 4 Leaded Zinc (5% Lead)............ x 
 maeeeaic Lead Sulfate.................... Xx 
 
¥ 
 
 White _ 
 spherical shape 
 king the oil — 
 
 5 3B [a 
 > Pe |r 
 Seu = g 
 NL e &le& 
 x S ibd] bpS| bo] [PS [PM [Pd P< |X 
 SE Ret 0 8 a> 
 aS %o}/ad 
 3 oe] ge 
 = iy BS 
 a |p N 
 2 \ 
 YN SS 
 B 
 — 
 Ww é 
 oy —_— 
 => 
 Bi scl kh & IX 
 roby Nes 
 an - © 
 O] as 
 = 
 By Be 
 2) <0 ome a ei aaa ea) ei Camieen laa 
 ov Be OS ae he ad 
 q et ae ied en rr 
 W af toa lea petite 
 — cal : “2 BSI Wares Ben Lad an 
 "Oo med tiie bam ies ee a een 
 5 ee alee sais 
 rh eae eeaeg oee ae dac, athe 
 P A : = ae a 
 Ss mie. Lor be Sle alts 
 @| 2 q ap ey ah re ; rt (a 
 O18 8 3 SAN aon aed tare eo: 
 ole Ic as) Pad acd oe 
 g ge |=lalelsi*\s 
 1S K| oO Y | 
 Hobo oi Sha] Sie 
 “a)5 o o | &~|'O 1B 
 Ale = Hl) aia |Clola 
 B}] a ae) Bia | 8} 9) 4a] 
 09 jaa ee) O MiSs lOiM hale 
 Ww © |t [oe] DIC Is In [oO | 
 © Sie ie isi 
 
 FIGURE 218 
 
 FIGURE 217 
 
 Fig. 217.— Before Shaking : 
 
 aves a series of milky threads caused 
 
 yer linseed oil, lower layer water. 
 It then drops rapidly in a 
 
 toward the surface. 
 Upper layer alcohol, lower layer linseed oil. White — 
 
 Occluded oil and air are seen in a struggle to rise ; 
 
 Upper la) 
 
 as it drops through the oil le 
 action of the oil. 
 
 to bottom of water layer. 
 
 to} #) 
 Pee 
 om 
 eed 
 —_ 
 = 2 
 bp > 
 a2 
 on 
 S pb, 
 ss 
 
 eads, showing rapid wetting — 
 have beeome fairly air-free 
 
 through the alcohol and upon stri 
 
 ement drops with rapidity 
 se downward in heavy milky thr 
 
 5S 
 starts to diffu 
 action of the oil upon the pigment which may 
 
 Fig. 218.—Before Shaking : 
 
 lead pi 
 
 by the alcohol bath. 
 * Under proper conditions and with sufficient agitation the lead should — 
 
 go into the oil phase. 
 
Miscellaneous Chemical Tests 659 
 
 Upper Layer Lower Layer 
 Linseed Oil Water 
 
 DUNE ee DIETING... 5.05.6. ccs. ceeeecceeeeeee. mS 
 
 DIP UTDCT bcc lee eceeess xX 
 
 DS oh chen oes ees ceevvveesenceeeess Xx 
 
 Bee ern -Ptack = oo... tcc. 8 
 
 BOM SPATE eee xX Some suspended 
 
 below oil layer 
 
 20 Light Green 25% on Barytes- 
 Re nese teaviee es xX 
 
 Testing the Settling Properties of Some Grades of Pig- 
 ments.—In Hig. 219 is shown a series of 100 cc. cylinders 
 containing oil paints made with 10 different grades of whit- 
 ing. That some grades settle much more rapidly than others 
 is indicated by the photograph. This method of testing the 
 settling properties of pigments may be extended to practically 
 any type of white pigment, and may give some useful infor- 
 mation. 
 
 FIGURE 219 
 
 Settling Tests on paints containing whiting. 
 
 Ten grams of each of the samples of whiting were also 
 placed in 100 ce. graduated cylinders, which were then filled 
 with water and shaken. The time of settling of each of these 
 cylinders was measured accurately with a stop watch. The 
 figures given in the table are ce. of clear water from which all 
 the pigment has settled: 
 
660 Miscellaneous Chemical Tests 
 TA Shy AO Ry QO S eo) i) QS Re 
 Janis gcar ke 1325-15 110 ee 6... “41 > AO ae eee 
 2 rit NS 27. 28 «= «2439 
 Prin es 40 38 36  S&4 (36 47 9 97 epO meee 
 doming foes es 52 48 48 67 53° 290935 nnn 
 Bambtie ee ee 67. 57. 59 +73 58 | 28) ste cee 
 6 malty sue oe 75° 63 . 68 76 64 409 50 0g eee eee 
 Fi minin tose 775 675 72 79 68 — 3000 57 ge 
 S ming. cae 79.5 705 75 81. 41 © 45 60 61 =eyeeee ene 
 Ormins 81. 71.5 77 82.5 74 @)48°50 cee 
 10 Min. eee 82.5 72.5 79 $4.0: 77 05206) 
 
 SETTLING TESTS ON PAINTS 
 Put out Nov. 23, 1925, 11 a. m. Oil paint placed to extent of 6-inch depth 
 
 in 8-inch test tubes. 
 
 1 2 3 
 6 hours None None None 
 24 “ None None None 
 48 “ None None None 
 1 week 4mm. 6mm. 4mm. 
 
 5 months 25.3% 30.1% 22.8% 
 
 4 b 
 None None 
 None None 
 
 None None 
 
 4mm. 2mm. 
 
 14.1% 15.0% 
 
 6 7 8 
 
 None None None 
 
 None None None 
 None None None 
 0 0 0 
 7.5% 13.9% 12.7% 
 
 9 
 None 
 None 
 None 
 
 0 
 5.0% 
 
 10 
 None 
 None 
 None 
 
 0 
 6.3% 
 
 50 ce. oil paint and 50 cc. mineral spirits shaken together and placed in 100 cc. 
 
 glass cylinders. 
 
 G6: hours * 63:62". 73:5) ea rey 
 24 4 50.5 43.5 50.5 
 45 44.0 386 44.8 
 week 35.0 33.5 34.5 
 
 Figures above show cc. mark to which white pigment has settled. 
 
 65,06 2-02 
 
 51.50 SL 
 45.5 46.0 
 34.8 38.5 
 
 93.5. 93.8.) ae 
 16:5 - 043 Ore 
 62.5). $5.0 Bae 
 43,5. 38.3 oe 
 
 96.5 
 92.0 
 86.0 
 61.5 
 
 913 
 87.0 
 
 74.5 | 
 
 54.5 
 
 Testing the Particle Size of Pigments.—The method devel- 
 oped by Stutz and Pfund for determining the particle size of 
 pigments and originally published in Industrial and Engineer- 
 ing Chemistry for January, 1927, has proved entirely satis- 
 
 factory for this work. A description of his method is presented ¥ 
 
 below. 
 
 - 
 A 
 = 
 C4 
 we 
 t 
 ee 
 
 eee ee. ee Torey) gery, 
 Se ot Ae Mh omy ote 
 
 tig 
 
Miscellaneous Chemical Tests 661 
 
 “Apparatus.—A ribbon filament lamp, Iy,, (Fig. 220), is con- 
 nected to a 6-volt storage battery through an ammeter and 
 variable resistance. The current through the lamp can be 
 kept constant, and at any desired value, over long periods of 
 time. Light from this lamp is rendered parallel by means of 
 the lens 4, and passes through a suspension of the pigment to 
 
 Diagram of Particle Size Apparatus 
 FIGURE 220 
 
 be measured, contained in the cell F. This cell is of brass, 3 
 inches long, with glass windows cemented in each end. The 
 parallel light transmitted through the cell is focused by means 
 of the lens C in the plane of the filament of the lamp L,. The 
 total reflection prism, P, reflects the beam at right angles to 
 its initial direction. The eye, placed at the aperture S, focuses 
 by means of the lens D on the filament of lamp D2, superim- 
 posed on the image of the filament of lamp Z,. A screen of 
 red or green glass is introduced at the aperture S, to limit the 
 wave length of the light used and eliminate color differences. 
 Lamp Lz is the lamp from an optical pyrometer eye-piece. It 
 is connected to a variable resistance, dry cells, and milliam- 
 meter, H. By rotating the disk at the side of the box E, the 
 current through the filament of lamp L, may be varied until 
 the filament equals in brightness that of the image of the fila- 
 Ment of the lamp L,. The intensity of the light transmitted 
 by the suspension is then measured in terms of milliamperes 
 of current through the lamp L:. 
 
 ‘The two objects to be matched in brightness are similar— 
 that is, both are lamp filaments. There is consequently but 
 
662 Miscellaneous Chemical Tests 
 
 little color difference and photometric settings can be made 
 with ease and accuracy. The fact that the light beam, while 
 passing through the suspension, is parallel makes each particle : 
 effective in reducing the light intensity, and is therefore more 
 sensitive than the use of a diverging light beam. 
 
 a 
 3 
 
 eres of Current 
 
 Mx 
 e 
 
 illiam 
 
 . . Bebe 
 giAt | et 
 Z 370 
 
 AREOEBE 
 ut 
 
 (Ts : | 
 meee size wea Hr rb e 
 
 FIGURE 221 
 Particle Size-Relationship, Refractive Index of Vehicle 1.33 
 
 “¢ Procedure.—Thus far the instrument has been used chiefly — 
 to measure zine oxides. For this material the suspension, ~ 
 which contains 0.0000694 gram of zine oxide per cubic centi- — 
 meter, is made as follows: 0.20 gram of zinc oxide, 0.10 gram of — 
 eum aac and 0.05 gram of saponin are ground for 8 minutes — 
 with 1 ec. of 0.05 N potassium ferrocyanide solution, ina glass | 
 mortar with a glass pestle; the paste is then diluted with 90 — 
 ec. of water and shaken vigorously. Five cubic centimeters — 
 of this suspension are diluted to 200 ce. with water, and this — 
 latter is used in the determination. It is found that two ob- — 
 servers can check one another within one division (2 — 
 milliamperes) on the same suspension. Furthermore, two ~ 
 separate suspensions made of the same material will check € 
 within one and one-half divisions (3 milliamperes). . 
 
 ‘In order to keep the instrument in constant adjustment, — 3 
 it is only necessary to keep the current through the lamp J; ‘ 
 
Miscellaneous Chemical Tests 663 
 
 constant. However, it is more satisfactory to make use of a 
 constant standard of turbidity, and to adjust the current 
 through L, until this standard gives a definite reading. As 
 a standard, a piece of Corning turbid glass (G632J) approxi- 
 mately 5 mm. thick is placed in the cell and the cell filled with 
 clear water. | 
 
 “Results —Fig. 221 shows the results obtained on a series 
 of zine oxides dispersed in water (refractive index 1.33). The 
 ordinates are the readings on the opacity instrument in milli- 
 amperes of current through lamp L,. The abscissas are par- 
 ticle size readings in microns. For materials over 0.2 micron 
 the particle size was determined by the method of Green. For 
 samples under 0.2 micron the particle size was determined 
 
 Zine Oxides of Different Particle Sizes. 
 
 Average Method 
 
 Particle _ of Particle 
 
 Pigment Process of Manufacture Size u Size Detn. 
 A Reheated American 1.18 Green 
 B Reheated American 0.679 Green 
 C Reheated American 0.484 Green 
 D Reheated American 0.436 Green 
 EB Special American 0.276 Green 
 F French 0.246 Green 
 G French 0.238 Green 
 H Kadox 0.180 Count 
 J Kadox 0.125 Count 
 
 —— 
 
 by the count method using a dark-ground illuminator and 
 counting chamber. The diameter so determined is based on 
 the number of particles per unit volume and is not entirely 
 comparable with the diameter obtained by Green’s method. 
 However, it is the only satisfactory absolute measurement that 
 has been obtained for this very fine material.’ 
 
 Testing the Physiological Action of Oils—In determining 
 the possible toxic or non-toxic character of new oils which 
 may come into the industry, small animals may be used. A 
 record of some experiments in this direction is given below. 
 In these tests the physiological effects of tung oil upon rabbits 
 and dogs were recorded. An outline of the method is given 
 below: 
 
 Preliminary experiments on raw tung oil were run with 
 rabbits, beginning with small doses of 1/10 ee. The animals 
 were observed for any pathalogical manifestations, symptoms 
 
664 Miscellaneous Chemical Tests 
 
 or organic pathology, together with the effect upon peristalsis 
 of bowel movements and loosening of stool. 
 
 On February 1, 2, 3, 4, 5, three rabbits were given 1/10, 
 2/10, 3/10, 4/10, and 5/10, respectively, of raw tung oil. The 
 animals exhibited no symptoms of an abnormal character; 
 apparently the material did not affect their appetite and abso- 
 lutely no change was observed in the dejecta. 
 
 Large black rabbit, weighing 7 pounds, 6 ounces, was chosen 
 for more intensive dosage. On February 17, 1926, given 2 ce. 
 directly into stomach by syringe and catheter; no symptoms 
 of anorexia, restlessness or other pathological manifestations 
 were observed. Stools following day showed no change in 
 character from normal. 
 
 February 18, 1926, 5 ec. given directly into stomach by 
 syringe and catheter. No symptoms were observed except 
 slight indisposition to eat directly following administration 
 of the preparation. No other symptomatology noted. Stools 
 well formed, slightly darker than normal, and exhibited ten- 
 dency to be slightly greasy; otherwise, no appreciable effect. 
 Movements not increased over their normal character. 
 
 February 23, 1926, animal’s weight the same; given 7 ce. 
 directly into stomach by syringe and catheter. Animal ex- 
 hibited some anorexia, some slight discomfort and indisposi- 
 tion to eat shortly after administration. On February 24 
 
 there was some increased defecation; stool soft, dark, but still — 
 
 well formed. Character manifested was that of slight laxative 
 effect. 
 
 Testing Aluminum Stearate.—Aluminum stearate has been 
 used in considerable quantities during recent years, in the 
 paint and varnish industries. It is used for producing certain 
 physical conditions, such as body and non-settling in prepared 
 paints; waterproofing and flatting properties in interior wall 
 paints, and to induce a rubbed-finish appearance in some fur- 
 niture varnishes. The extent to which these conditions are 
 obtained in a product appear to depend upon or be related to 
 the degree of viscosity which the stearate will impart to the 
 liquid, iis in turn, is influenced by the Duy texture, etc., 
 of the stearate, 
 
 Several manufacturers using aluminum stearate have expe- 
 rienced difficulties due to non-uniformity of different lots re- 
 
 Pf 
 ‘et 
 as 
 
 3 ate 
 =! 
 , 
 » 
 a 
 aa 
 
Miscellaneous Chemical Tests 665 
 
 ceived.” In the present investigation it has been found that 
 different brands vary greatly in both chemical composition 
 and physical properties. In view of the variation of the differ- 
 ent brands, it would seem desirable to have specifications, com- 
 pliance with which would insure the suitability of the material. 
 
 Visual Examination.—For the present investigation, a num- 
 ber of samples were obtained from producers and users of 
 aluminum stearate. It was found that much could be learned 
 concerning their suitability by visual examination. For in- 
 stance, those samples which are readily soluble and which im- 
 part the higher viscosities to solutions are almost invariably 
 the ones that are finely divided. When stirred up in a liquid, 
 colorless paraffin oil, for instance, the more finely divided stear- 
 ates yield milky liquids in which no coarse particles are vis- 
 ible. Other samples (coarse) contain lumps or agglomerates 
 which do not break up on stirring and settle very quickly. 
 When examined under the microscope some samples are seen 
 to be of fine texture, and the particles, although apparently 
 not crystalline, are clearly defined and fairly uniform in size. 
 In other samples the material is seen to be more or less ag- 
 glomerated and present a very non-uniform appearance. 
 In those samples examined, which were found to contain free 
 stearate acid, the particles of the acid could readily be detected 
 under the microscope by their Semi-transparent appearance. 
 
 Solubility —Aluminum stearate does not appear to dissolve 
 appreciably in any solvent in the cold. It goes into solution in 
 a number of solvents quite readily, however, when heated. 
 When a mixture is heated, the stearate apparently softens and 
 then melts as the temperature is raised, subsequently being 
 dispersed through the liquid. The character of the solution 
 formed by the various stearates differs greatly. For instance, 
 in certain concentrations in a given solvent, one stearate will 
 yield only a thin liquid while another will yield a solid gel. 
 With certain samples precipitation occurs upon standing, and 
 the appearance of the solution changes, while in other cases 
 ho change is observable. 
 
 Solutions of samples Nos. 1 to 7 in turpentine, mineral 
 Spirits, and benzol were made. In each case 10 grams of dry 
 Stearate and 200 ce. of solvent were used. The stearate was 
 
 *The investigation to date has been facilitated by the suggestions of Dr. 
 P. S. Kennedy and Mr. H. M. Johnson, of the Murphy Varnish Co. 
 
Miscellaneous Chemical Tests 
 
 666 
 
 "Gg 0} [ sofdures 
 
 se AdUOYSISUOD 9UTVS oY} YNoqe Jo e1eM ‘paArossIp A[e}e[duIo0o 
 
 ysnoyye ‘2 pue g sojdureg “paalossip ojvive4s ey} Jo uorzs10d 
 [Lewis e@ A[uO asneoeq UIYy} 318 G 0} T So[duIes JO SUOTIN[OG :ALON 
 “AYIUL yeyMouos ‘uIy} AOA *L “ON 
 
 “UL0}}0Q 
 
 uo uorTjerIedes yusNo.0y [Teus ‘Ay Apyysts ‘uty, ATeA “9 “ON 
 ‘Apnop Aysts pue mopped A[ZySIs ‘ury} AToA g pue Ff “Eg °Z “SON 
 ‘uoI}NyOS oni} Ajjueredde ‘1va]o pue ssoptojoo ‘uly ATOA “T ‘ON 
 
 *MOT[eA 
 are Gg pue fF ‘g ‘Z “SSeTIOT[OO e1B J), pus 
 9 ‘T ‘pInbiy snosuesouoy ‘ulyy 8 04 
 Ajisee pue Ajoze[dulod sA[OSSIp 1, pue g 
 sojdwieg ‘onpiset sty} JO 910UL 9AlOS 
 -SIp 0} 1vedde jou soop s10ul 10 InoYy 
 ue IO} Sul[log penulzu0g “ysey oy} ul 
 (eoo1de}, Sul[quieser) onpiset snourze 
 -[a3 ‘Ayorys @ Sulave] ‘Ajojye[duiooul pues 
 
 A[MOJ[S SATOSsIp Gg pue fF ‘g ‘Z ‘T Setdueg 
 
 jozueg 
 
 ee eT Sa aes AOR NED EES eg el a ra IL SE Cat Lt SE ecient See SRE ee ahaa CIA eR Ea Sh IE POT GNS., RL IK Lie RE LR I RE I Oe a ie Se PPS See 
 
 ‘ULI, OLOW JVYMOEWIOS Suleq 9 ‘ 
 ‘ON “4Qnoysno1yy AoUSYSTSUOD UUAIOJIUN JO STes 4ZOS a1B }, pue g “SO 
 ‘pinbr, uly} pue jes 
 way ‘soseyd OM} JO SUTSISUOD ‘IeTIWIS ATOA o1B G pue fF ‘g ‘Z “SON 
 ‘qnoysnoiy} Waostun “Jos oytyM-AY[TUM “POS “T “ON 
 
 ‘MOT[eA SSO] 10 BLOW 918 
 SI9YjO 9Y} eIYM ‘sse[Lojoo AT[eoyoesd 
 aie 2 pue 9 ‘T ‘SON ‘fod Ys eB pue 
 pinbi, uty3 Area @ ‘soseyd 4OUTYSIP OA} 
 Jo ystsuod g pue pF ‘g ‘Z ‘SON ‘JOS PHS 
 AoA @ SI T ‘ON ‘AdUodySISUOD UTOFIUN 
 Ajjeorpoeid JO sjed SNOOSIA e1B L pue 9 
 ‘SON ‘pojou SI souvivedde ul duets 
 -JIp o[GViloepIsuod SInoy Moy B SuIpuBys 
 IaiJV ‘SoyNuIW MejJ & SuI[Iog uo Ajaye[d 
 
 -ul0d pue A[IpBvel esAlOSSIp seidures [TV 
 
 sqaidg 
 [e19Uul 
 
 I 
 
 "9 “ON UPI [eoljuepy “L “ON 
 *“MOTeq JNO poyeredes 
 [elteyeu yusTNd.0p ‘doz uo pinbiy, Aveo pue ssejp1ofoo ‘UIYT, “9 “ON 
 ‘7 ON UPA [BoTJUOpUyT *G “ON 
 “MOTEq uUOol}eIedes JUeTNI.0y -prinbiy ystmorjeA ‘UINT, “fF “ON 
 ‘doz uo pinbiy uty} Jo JUNOUe [[eUIS Y4IM 4nq *Z ‘ON 0} TBIIWIS “§ “ON 
 “YSTMO[ 
 -jef pue Apnoyo ‘snoosta AroA ‘AduestsuoD WAojJtun ‘poeTjes “Z “ON 
 ‘Apnojo yeyMoulos ‘snovsta ATA ‘AOuSYSISUOD UATOFIUN ‘po[[es “T "ON 
 
 *IOTABOY 
 yonut AtoA 1B G OJ T ‘uIyy AOA 
 ere ), pue 9g Jo suoT{njog ~*MOT[aA Sse] 
 IO 910Ul a1e8 Si1eyjO fsseT1o[od A][eIT} 
 -ovid oie 2, puve g ‘T, ‘“suI[OOD uO 90UeB 
 -1eodde ul SnosuesowoYy a1e SUOTyN[OS 
 ITV ‘“seqnuru Moz eB SurTIog uo Ajeze[d 
 
 -u0d pues ATIpveat osATOSSIp so[dures [TV 
 
 suljuediny, 
 
 Pe Se laa ae ee ER Na a ea ee eS EIB eae RE a Raa NB a ie Gre ef Ltt, IS OR a Fl SPC Fae ee 
 
 Jaye, YYUOU T SUOI}BAIESGQ 
 
 SUOI}N[OS SUIyeUL 
 JO OWT} 7B SUOTPVATOSGO 
 
 quaAlOS 
 
 em 
 
 O2Uag pun spinidy JoLaU]T ‘gurquadan UL SIZDADITN {O UWO1NIOY—@) ATAV 
 « tl . KR - . 4 . J . A _ 
 
Miscellaneous Chemical Tests 667 
 
 dissolved by heating the mixture under a reflux condenser. 
 in Table 73 observations made during the test are tabulated. 
 It is realized that, in actual practice, stearates would probably 
 not be used in this manner, but the test, nevertheless, throws 
 some light on the possible behavior of different samples when 
 used in the ordinary way. 
 
 As stated above, a definite temperature is necessary for 
 bringing a given sample of stearate into solution in any sol- 
 vent. The boiling points of both turpentine and mineral spi- 
 its are considerably above the melting point of any sample 
 of stearate. As a result the stearate melts and is dispersed 
 through the liquid, forming a colloidal solution or gel. It is 
 beheved that the nature of the colloidal body formed deter- 
 mines to a large extent the value of a given sample as an 
 ingredient of paint and enamel. It should be noted, however, 
 that the turpentine solution of some samples differs markedly 
 from the mineral spirits solution of the samples. 
 
 Benzol, on the other hand, boils at a temperature consider- 
 ably below the melting point of aluminum stearate. Since 
 dispersion of the stearate does not occur to any considerable 
 extent much below its melting point, only a small quantity of 
 it is taken up by this liquid even after prolonged heating. In 
 the solution made as indicated above, the liquid, when poured 
 from the undissolved portion, was more nearly a true solution 
 than is possible to make in even dilute solutions in turpentine 
 and mineral spirits. By the use of the higher homologues of 
 benzol, however, it is possible to make much more concen- 
 trated and more viscous solutions. 
 
 VIScCosITY AND CONSISTENCY 'l'ESTS 
 
 Jelly Test—One manufacturer* of stearates uses as a con- 
 trol test a so-called jelly test. This test presumably indicates 
 relatively the degree of viscosity that different samples will 
 impart to a liquid. It is carried out as described below using 
 the apparatus shown in Fig. 222. 
 
 Heat 10 grams of aluminum stearate with 90 cc. crude paraf- 
 fin oil in a beaker of 200 ce. capacity to a temperature of 150° 
 C. Stir the mixture constantly while being heated. When 
 solution is complete, cool to about 10° C. 
 
 * Mallinckrodt Chemical Works. 
 
Miscellaneous Chemical Tests 
 
 668 
 
 te 
 LLL LLM 
 
 Vie 
 
 TNS: 
 
 9) 
 x 
 
 FIGURE 222 me 
 trength of gel made of Aluminum Stearate. — 
 
 i 
 
 ro" 
 
 os 
 
 a 
 
 ining s 
 
 Apparatus for determ 
 
Miscellaneous Chemical Tests 669 
 
 By this treatment a jelly is formed, which varies with differ- 
 ent samples from a soft oily mass to a hard, solid gel. 
 
 The firmness of the gel thus made is tested by means of the 
 apparatus shown in Fig. 83. The beaker containing the gel is 
 
 ght (No. 4), 
 Glass containers 
 
 Veil 
 
 Sample on 
 
 ts After Standing One Month—Sam- 
 gel. 
 
 solid 
 ly firm gel that has slumped down. 
 
 piri 
 a 
 
 is 
 
 FIGURE 223 
 
 Two Samples of Aluminum Stearate in Mineral S 
 
 ple on left (No. 1) unifo 
 
 ir 
 
 stency, mass 
 
 . 
 
 rm consl 
 
 shows a thin liquid phase and a fa 
 ted, 
 
 < 
 
 Inver 
 
 placed under the plunger. On the small scale pan on top of 
 the plunger another beaker is placed, and into this mercury 
 or shot is poured until the gel yields under the pressure. The 
 weight taken is the total weight of mercury, beaker, and 
 
 plunger. 
 
670 Miscellaneous Chemical Tests 
 
 As stated in a communication from the above concern, this 
 is a rather crude test, being intended only for comparisons. 
 It should be made on the various products under considera- 
 tion at the same time and under the same conditions. It is 
 
 further stated that when carried out as directed above, results — 
 
 will not check closer than 15 or 25 grams. 
 
 An apparatus was assembled and this test was applied to — 
 
 the samples under investigation. It was carried out as de- 
 scribed above, the gels being held at 10° C. for two hours to 
 insure a uniform temperature. In check determinations the 
 
 results differed considerably, sometimes varying as much as ~ 
 
 20 per cent. The difference between samples is so great, how- 
 
 ever, that even with this great variation the test may be of : 
 
 value. In making gels of different samples for a comparative 
 test the same oil should be used for all samples as the firmness 
 of the gel is slightly influenced by the viscosity of the oil. 
 
 Considerable information is obtained by observing the be- — 
 
 havior of the material during the process of heating and the 
 appearance of the gel after cooling. In the opinion of the 
 writer, these observations are more important than the firm- 
 ness test. 
 
 Solutions of stearates in turpentine and mineral spirits are — 
 not- suitable for consistency measurements because of their 
 non-homogenous nature. Solutions in paraffin oil may gel — 
 
 to a certain extent, even at low concentrations. Benzol solu- 
 
 tions of definite concentration are not readily made, as a por- 
 
 tion of the sample usually remains undissolved. A further 
 difficulty arises from the fact that the consistency of the above 
 
 solutions may change materially with the slightest agitation, 
 
 due to a breaking down of the gel structure. For instance, 
 when attempts were made to measure the viscosity of paraffin 
 solutions by the tube test, it was found that the inversion of 
 the tube alone was sufficient to cause a considerable change in 
 consistency. 
 
 The ‘‘viseosity induction’’ of a given stearate may, how-— 
 ever, be measured by the tube method, using a xylol solution. 
 
 Xylol gives the same type of solution as benzol, and on account 
 of the high boiling point of xylol, the stearate can be heated 
 sufficiently high to obtain the desired concentration. This 
 method, while not entirely satisfactory, yields good results 
 
 if definite conditions are maintained. Below a certain concen- 
 
Miscellaneous Chemical Tests 671 
 
 tration, aluminum stearate dissolves on boiling in xylol to a 
 colloidal solution fairly free from suspended matter. The con- 
 sistency does not appear to be greatly affected by agitation 
 due to handling the container, and remains constant over a 
 short period of time. It changes, however with age, usually 
 becoming thinner. It is, therefore, necessary to make consist- 
 ency determinations at a fixed time after preparing the solu- 
 tions in order to get concordant results. The exact procedure 
 was as follows: 
 
 Three and a half grams of stearate were weighed into a 
 200 ce. Erlenmeyer flask and 100 ee. xylol added. The liquid 
 was boiled for a few moments under a reflux condenser. The 
 solution was allowed to cool under the reflux and then removed 
 and stood aside for two hours, taking care that none of the 
 solvent was lost through evaporation. The viscosity of this 
 solution was determined in the usual way by the tube test, 
 making the test at about 25° C. 
 
 Johnson uses the following method for measuring the vis- 
 cosity of paraffin oil-stearate solutions: 
 
 Dissolve 5 grams of stearate in 100 ce. paraffin oil by heating 
 to 150° C. Dip a marked spatula into the solution to the mark, 
 and allow to drain until definite drops come off. Allow a drop 
 to fall on a glass plate inclined at an angle. The drop will 
 flow down to a greater or less distance, depending upon the 
 viscosity of the solution. The distance of flow gives a relative 
 measure of the viscosity of different solutions. 
 
 CHEMICAL EXAMINATION 
 
 Moisture.—Different lots of stearate vary in the amount 
 of moisture which they contain. 
 
 It may be determined in the usual manner—that is, by heat- 
 ing about 1 gram of the sample in an oven for 3 hours at about 
 105° C. A method used by Johnson gives somewhat more con- 
 cordant results, and is probably more accurate in the case of 
 low melting point stearates. The latter method is carried out 
 as follows: 
 
 Carefully desiccate a quantity of oleic acid by drying in a 
 moisture oven for several hours. Weigh into a small portion 
 of the desiccated acid about one gram of the sample. Heat at 
 105° C. for 3 hours and determine the loss in weight. 
 
 While the percentage of moisture is usually relatively small, 
 it appears to influence the gelling properties of the sample, 
 
672 Miscellaneous Chemical Tests 
 
 FIGURE 224 
 
 Appearance of Three Gels Made of Aluminum 
 Stearates in Paraffin Oil—Upper sample (No. 12) 
 is very white and crumbly. Middle sample (No. J) 
 fairly white and crumbly like polymerized Tung 
 Oil. Sample (No. 6) at bottom is soft and smeary 
 like vaseline. Note how it flows. 
 
Miscellaneous Chemical Tests 673 
 
 or to be related to it in some way. Several users specify a low 
 moisture content stearate, and at least one manufacturer at- 
 tempts to keep the percentage in his product at 0.5 per cent 
 or less. Upon the suggestion of E. J. Cole, several experi- 
 ments were made to determine the effect on the gelling prop- 
 erty of water soluble compounds that may be present. Small 
 quantities of water, sodium sulphate solution, and sodium 
 hydroxide solution were added to separate 10 gram portions 
 of No. 1 stearate. To each, 90 ec. paraffin oil was added and 
 the mixtures gelled as described in the jelly test. The samples 
 to which pure water and sodium sulphate solution were added 
 yielded gels apparently as firm as when nothing was added. 
 The sample to which sodium hydroxide (a fraction of one per 
 cent) was added, remained very thin throughout the entire 
 heating, and when cold was very soft, similar to Nos. 6 and 7. 
 The appearance was that of a highly refined Petrolatum Jelly 
 (vaseline), for which it might serve in some arts. Apparently 
 caustic alkalies have a very marked effect upon the jelling 
 of Aluminum Stearate. 
 
 In Table 74 are given the moisture content and water 
 soluble in the samples examined. In general the samples of 
 lowest moisture content have the smallest proportion of water 
 soluble. Table 73, studied in connection with the experi- 
 ments described in the previous paragraph, indicates that 
 while the percentage of moisture may not in itself necessarily 
 influence the viscosity of stearate solutions, yet it suggests the 
 presence of compounds which do have this effect, 
 
 Total Ash, Aluminum Oxide, and Water Soluble.—The de- 
 termination of these constituents is an important part of the 
 chemical examination. They are easily and quickly deter- 
 mined, and are valuable indications of quality. Of the sam- 
 ples under investigation, those which have the lowest viscosity 
 induction values have a high percentage of water soluble, 
 while in those yielding the most viscous solutions, the water 
 soluble content is very low. These determinations were car- 
 ried out as follows: 
 
 About five grams of the sample was weighed into a silica 
 crucible and carefully ignited over a Bunsen flame. The resi- 
 due was reported as total ash. The crucible was then placed 
 in a 400 ec. beaker and treated with boiling water to dissolve 
 the water soluble portion. The solution was filtered through 
 a quantitative paper and the paper burned in the same cruci- 
 
Miscellaneous Chemical Tests 
 
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 ble. The second ashing represents Al,O. with the traces of 
 iron and other impurities that may be present and the differ- 
 ence between the two weighings represents the water soluble. 
 
 Tron.—The presence of iron is readily detected by the yellow- 
 ish red color which it imparts to the stearate solutions. The 
 proportion is usually very low, less than .1 percent. In such 
 small amounts it would have no effect on quality, except in so 
 far as color'is concerned. Traces were found in both good and 
 poor samples, hence it is believed that a quantitative deter- 
 mination is unnecessary except possibly when the material 
 is to be used in a white or very light-colored product. Even in 
 the latter case observations of the color of solution alone would 
 probably be sufficient. 
 
 Conclusions.—The viscosity or ‘‘body’’ of solutions of alu- 
 minum stearate in a given solvent varies enormously for differ- 
 ent samples of stearate. Comparing the results of the firmness 
 test with the viscosity of xylol solutions (Table 74), it ap- 
 pears that the viscosity also varies with the solvent used. For 
 instance, Sample No. 8, which showed a rather high yield 
 point in the firmness test, produced a solution of very low vis- 
 cosity when dissolved in xylol. 
 
 The chemical examination has not proceeded far enough to 
 draw any very definite conclusions. It appears, however, that 
 the percentage of water soluble matter is important since those 
 samples having the highest percentage, in general yield the 
 least viscous solutions. The proportion of unneutralized 
 Stearic acid and of aluminum oleate probably modify to a 
 certain extent the physical properties. 
 
 SuGcEsteD TenrTaTive SPECIFICATIONS For ALUMINUM STEARATE, 
 
 The aluminum stearate must be finely divided and satisfac- 
 tory for use in the paint and varnish industry. It must be 
 white in color, and contain not over 0.1 per cent iron as FesOs. 
 
 Moisture.—It shall contain not more than 1.5 per cent of 
 moisture. | 
 
 Water Soluble—It shall contain not more than 2.0 per cent 
 of water soluble material. , 
 
 Water Insoluble Ash.—The ash from the water insoluble 
 material shall be not less than 6.0 per cent. 
 
 Appearance of Solution—When 2 grams of aluminum stear- 
 ate is dissolved in 50 grams of xylol, a practically colorless and 
 fairly clear solution shall be obtained. 
 
CHAPTER XXXVIII 
 
 ANALYSIS OF PAINTS 
 
 The material presented on this subject in the previous edi- 
 tions of this volume is now superseded by the A. 8. T. M. 
 Tentative Methods of Routine Analysis of White Linseed Oil 
 Paints, which are presented below. Following these methods 
 will be found some special methods used in this laboratory 
 for the identification of various oils in paint liquids. 
 
 It is most important in taking samples of paint for analysis 
 to insure uniformity. In Fig. 225 a method of thoroughly 
 ‘“boxing’’ paint is shown. The writer remembers some trouble 
 that was experienced by one of the government bureaus a few 
 years ago in securing the expected analytical results, insofar 
 as pigment concentration was concerned, on shipments of 
 paint to one of the government agencies. It was found that 
 while the inspector had thoroughly stirred 5 gallon packages 
 before taking the samples, the packages were not ‘‘boxed’’ and 
 therefore the analyst failed to secure the expected results. 
 
 A. S. T. M. TENTATIVE METHODS OF ROUTINE ANALYSIS 
 OF WHITE LINSEED OIL PAINTS 
 PRELIMINARY PROCEDURE 
 
 On receipt of a sample make a record of the label, noting especially the 
 
 brand, the name of the manufacturer, and any statements as to composition - 
 
 and net contents. Weigh the unbroken package, open, note odor and condition 
 of the contents, pour into a clean container, and mix thoroughly by pouring 
 from one container to the other, finally leaving the well-mixed sample in the 
 second container, which shall be tightly closed. The well-mixed sample is used 
 at once for the determinations described under ‘‘Methods.” The original can 
 and cover may be cleaned with gasoline, wiped dry, and then weighed. This 
 weight subtracted from the original weight will give the net weight of the 
 contents. If desired, the specific gravity of the paint may be determined and 
 the weight per gallon calculated, and the volume of paint and the capacity of 
 the container may be measured. 
 
 REAGENTS REQUIRED 
 Extraction Miature.—10 volumes ether (ethyl ether) ; 
 
 6 volumes benzol; 
 
 4 volumes methyl alcohol; 
 
 1 volume acetone. 
 
 Aqueous Sodium Hydroxide.—Dissolve 100 g. of NaOH in distilled water 
 and dilute to 300 ce. 
 
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 Analysis of Paints 
 
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678 Analysis of Paints 
 
 Alcoholic Sodium Hydroxide Solution. Dissolve pure NaOH in 95-per-cent 
 ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 
 stoppered bottle. Decant the clear liquid into another bottle and keep well 
 stoppered. This solution should be colorless or only slightly yellow when used, 
 and it will keep colorless longer if the alcohol is previously treated with 
 sodium hydroxide (about 80 g. to 1000 ¢c.), kept at about 50° C. for 15 days, 
 and then distilled. 
 
 Wijs Solution.—Dissolve iodine in glacial acetic acid that has a melting 
 point of 14.7 to 15° C. and is free from reducing impurities in the proportion so 
 that 13 g. of iodine will be present in 1000 cc. of solution. The preparation of 
 the iodine monochloride solution presents no great difficulty but it shall be done 
 with care and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine or more particularly of 
 chlorine over that required to form the monochloride. This condition is most 
 satisfactorily attained by dissolving in the whole of the acetic acid to be used 
 
 the requisite quantity of iodine, using a gentle heat to assist the solution, if it. 
 
 is found necessary. Set aside a small portion of this solution while pure, 
 and pass dry chlorine into the remainder until the halogen contemut of the 
 Solution is doubled. Ordinarily, it will be found that by passing the chlorine 
 into the main part of the solution until the characteristic color of free iodine 
 has just been discharged, there will be a slight excess of chlorine which is 
 corrected by the addition of the requisite amount of the unchlorinated portion 
 until all free chlorine has been destroyed. <A slight excess of iodine does little 
 or no harm, but excess of chlorine must be avoided. 
 
 Standard Sodium Thiosulfate Solution—Dissolve pure sodium thiosulfate 
 in distilled water (that has been well boiled to free it from carbon dioxide) 
 in the proportion of 24.83 g. crystallized sodium thiosulfate to 1000 ec. of the 
 solution. It is best to let this solution stand for about two weeks before 
 standardizing. Standardize with pure resublimed iodine, pure potassium 
 biiodate, or pure KIO, (see Treadwell-Hall, Analytical Chemistry, Vol 2.) 
 This solution will be approximately 0.1N, and it is best to leave it as it is 
 after determining its exact iodine value, rather than to attempt to adjust 
 it to exactly 0.1 N. Preserve in a stock bottle provided with a guard tube 
 filled with soda lime. 
 
 Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. of soluble starch 
 with 100 ce. of 1-per-cent salicylic acid solution, add 300 to 400 cc. of boiling 
 
 water, and boil the mixture until the starch is practically dissolved, then — 
 
 dilute to 1 liter. 
 
 Potassium Iodide Solution.—Dissolve 150 g. of potassium iodide free from 
 iodate in distilled water and dilute to 1000 ce. 
 
 Acid Ammonium Acetate Solution.—Mix 150 ce. of 80-per-cent acetic acid, 
 100 cc. of water, and 95 ce. of strong ammonia (sp. gr. 0.90). 
 
 Ammonium Polysulfide—Pass H,S gas into 200 ce. of strong ammonium 
 hydroxide (sp. gr. 0.90) in a bottle immersed in running water or in iced 
 water until the gas is no longer absorbed; then add 200 ce. of strong ammonium 
 hydroxide (sp. gr. 0.90) and dilute with water to 1000 ce. Digest this solution 
 with 25 g. of flowers of sulfur for several hours and filter. 
 
 “read Acid.”—Mix 300 ce. of H.SO, (sp. gr. 1.84) and 1800 ec. of distilled 
 water. Dissolve 1 g. of c. p. lead acetate in 300 ce. of distilled water and add 
 
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Analysis of Paints 679 
 
 this to the hot solution, stirring meanwhile. Let stand at least 24 hours and 
 siphon through a thick asbestos filter. 
 
 Potassium Permanganate NSolution.—Dissolve 3.2 g. of pure potassium 
 permanganate in a liter of distilled water, let stand 8 to 14 days, siphon 
 off the clear solution (or filter through an asbestos filter), and standardize 
 as follows: In a 400-cc. beaker dissolve 0.25 to 0.30 g. (accurately weighed) 
 of Bureau of Standards’ sodium oxalate in 250 ce. of hot water (SO to 90° C.) 
 and add 15 ec. of dilute sulfuric acid (1:1). Titrate at once with the potas-: 
 sium permanganate solution, stirring the liquid vigorously and continuously. 
 The permanganate must not be added more rapidly than 10 to 15 ce. per 
 minute, and the last 0.5 to 1 cc. must be added dropwise with particular 
 care to allow each drop to be fully decolorized before the next is introduced. 
 The temperature of the solution should not be below 60° C. by the time the 
 end point is reached. (Too rapid cooling may be prevented by allowing the 
 beaker to stand in a small asbestos-covered hot pkate during the titration. 
 The use of a small thermometer as a stirring rod is most convenient.) The 
 weight of sodium oxalate used multiplied by 0.833 gives its iron equivalent. 
 The permanganate solution should be kept in a glass stoppered bottle painted 
 black to keep out light. 
 
 The iron (Fe) value of the KMnO, multiplied by 1.076 theoretically equals 
 its antimony (Sb) equivalent. However, for use in determining antimony, 
 the KMnO, is best standardized as follows: To 0.25 g. of pure metallic anti- 
 mony in a 500-cc. Pyrex Erlenmeyer flask, add 12 to 15 ec. of concentrated 
 H,SO, and 10 to 12 g. of K.SO,; heat until all the antimony is dissolved, 
 cool, dilute to 250 cc. with water, add 20 cc. of concentrated HCl, cool to 10 to 
 15° C., and titrate with the KMnO, solution until a faint pink color is ob- 
 tained. For special work, after digesting, dilute to 100 cc. with water, add 
 1 to 2 g. of Na,SO,, and boil until all the SO, is expelled. This is shown 
 when no blue color is obtained with starch-iodate paper (see below); the 
 volume will be reduced about one-half. Dilute to 250 ce. with water, add 
 20 ce. of HCl (sp. gr. 1.19), and complete as described. 
 
 Standard Potassium Ferrocyanide.—Dissolve 22 g. of the pure salt in water 
 and dilute to 1000 ce. To standardize, transfer about 0.2 g. (accurately 
 weighed) of pure metallic zine or freshly ignited pure zine oxide to a 400-cc. 
 beaker. Dissolve in 10 cc. of HCl and 20 cc. of water. Drop in a small piece 
 of litmus paper, add ammonium hydroxide until slightly alkaline, then add 
 HCl until just acid, and then 3 ce. of strong HCl. Dilute to about 250 ce. 
 with hot water and heat nearly to boiling. Run in the ferrocyanide solution 
 Slowly from a burette with constant stirring until a drop tested on a white 
 porcelain plate with a drop of the uranyl indicator shows a brown tinge after 
 standing one minute. A blank should be run with the same amounts of 
 reagents and water as in the standardization. The amount of ferrocyanide 
 solution required for the blank should be subtracted from the amounts used 
 in standardization and in titration of the sample. The standardization must 
 be made under the same conditions of temperature, volume and acidity as 
 obtained when the sample is titrated. 
 
 Uranyl Indicator for Zine Titration.—A 5-per-cent solution of uranyl 
 nitrate in water or a 5-per-cent solution #f uranyl acetate in water made 
 slightly acid with acetic acid. 
 
680 Analysis of Paints 
 
 Alkaline Lead Nitrate Solution—lInto 100 ce. of KOH solution (56 g. in 
 140 cc. of water) pour a saturated solution of lead nitrate (250 g. in 500 ce. 
 of water) until the precipitate ceases to redissolve, stirring constantly while 
 mixing. Let settle, filter through asbestos, and dilute the clear filtrate with 
 an equal volume of water. About 3 volumes of the lead nitrate solution will 
 be required for one of the KOH. 
 
 Ammoniacal Cadmium Chloride or Zine Sulfate Solution.—Dissolve 8 g. 
 of cadmium chloride in 200 ce. of water and add 200 ec. of NH,OH (sp. gr. 
 0.90), or, dissolve 200 g. of zine sulfate in 1080 ec. of water and 920 ce. of 
 NH,OH (sp. gr. 0.90). 
 
 Standard Potassium Iodate Solution.—Dissolve 3.6 g. of KIO, and 39 g. 
 of KI in 1000 ce. of water. For general work the theoretical sulfur titer of 
 this solution should be used; for special work, the solution may be standard- 
 ized against like material, such as a lithopone of known sulfide sulfur content. 
 The theoretical titer is based on standard Na,C,O, and is obtained as follows: 
 To 300 ce. of water in a 600-cc. flask, preferably glass stoppered, add 10 ce. 
 of concentrated HCl (sp. gr. 1.19) and 1 g. of KI.- Cool and add 10 ce. of 0.1 
 N KMn0O, solution which has been standardized against Na.C,0, Swirl 
 gently, stopper, and let stand for five minutes. Titrate the liberated iodine 
 with standard Na.S.O, solution until the color fades. Then add 10 ce. of 
 starch solution and continue the titration until the blue color is destroyed. 
 Repeat the titration with the sole difference that 10 ee. of the iodate solution 
 is substituted for the KMnOy, solution. Calculate the normality of the iodate 
 solution. 
 
 Starch Indicator for Sulfur Titration.—(1) To 1000 ce. of boiling water, 
 add a cold suspension of 6 g. of starch in 100 ce. of water and boil vigorously 
 for five minutes. Cool the solution, add 6 g. of ZnCl, dissolved in 50 ce. of 
 cold water, thoroughly mix and set aside for 24 hours. Decant the clear 
 oughly. (2, Optional.) Prepare an emulsion of 6 g. of soluble starch in 25 ce. 
 Supernatant liquid into a suitable container, add 3 g. of KI, and mix thor- 
 of water, add a solution of 1 g. of NaOH in 10 ce. of water, and stir the 
 solution until it gelatinizes. Dilute to 1000 cc. with water, add 3 g. of KI, 
 and mix thoroughly. 
 
 Starch-lodate Paper.—Impregnate filter paper with a solution obtained by 
 heating 2 g. of starch with 100 ce. of water, and, after solution, adding 0.2 g. 
 of KIO, dissolved in 5 ce. of water. 
 
 Standard Iodine Solution for SO,—Place 15 to 20 g. of pure KI in a liter 
 flask, dissolve in as little water as possible, and then add about 6.4 g. of 
 resublimed iodine. Shake until the iodine is all dissolved, dilute to the mark 
 with water, and mix. This solution is approximately 0.05 N and is standard- 
 ized against 0.05 N Na.S,O, to obtain its true normality. 
 
 Standard Sodium Thisulfate Solution for SOz—Prepare and standardize 
 as described above, except that 12.42 g. of pure crystallized Na.S,0,5H,O are 
 used or the 0.1 N solution may be diluted with an equal volume of cold CO,- 
 free water. 
 
 METHODS 
 WATER (NOTE 1) 
 
 Mix 100 g. of the paint in a 250-ce. flask with 75 ce. of toluene. Place the 
 
 flask in an oil bath, connect with condenser, apply heat to the bath, and distil 
 until about 50 ee. of distillate have been collected in a graduate. The tempera- 
 
Analysis of Paints 681 
 
 ture in the flask should be then about 105 to 110° C. The number of cubic 
 centimeters of water collected under the toluene in the receiver is the per- 
 centage of water in the paint. 
 
 VOLATILE THINNER 
 Weigh accurately from 3 to 5 g. of the paint into a tared flat-bottomed 
 dish about 8 cm. in diameter, spreading the paint over the bottom. Heat at 
 105 to 110° C. for one hour, cool, and weigh. Calculate the loss in weight as 
 percentage of water and volatile thinner, subtract from this the percentage 
 of water (1), and report the remainder as volatile thinner, 
 
 NATURE OF THE THINNER 
 
 Transfer about 150 g. of the paint to a 500-ce. flask fitted with a 2-hole cork 
 stopper carrying a spray trap connected with a vertical condenser. ‘Through 
 the other hole in the stopper pass an influx tube for steam. (This tube 
 should dip below the surface of the paint.) Heat the flask in an oil bath 
 or an air bath at 100° C. and pass through it a current of steam; with the 
 steam still passing through, raise the temperature of the bath to 130° C. 
 Catch the distillate in a small separatory funnel; continue distillation until 
 300 ce. of water has been condensed. Portions of this water may be drawn 
 from the cock of the separatory funnel from time to time, but care must be 
 taken not to draw out any of the volatile thinner. Let the distillate stand 
 until it separates into two layers, then draw off the water, and filter the 
 _ volatile thinner through a dry filter paper into a dry flask. If the thinner 
 is apparently turpentine, examine the distillate by the methods described in 
 the Standard Methods of Sampling and Testing Turpentine (Serial Designa- 
 tion: D 233) of the American Society for Testing Materials.* If the thinner - 
 is a mixture of turpentine and mineral spirits, an approximate determination 
 of the amount of turpentine may be made by the polymerization test specified 
 for under turpentine. It should be noted that turpentine is slightly soluble 
 in water (about 0.3 to 0.4 ce. per 100 ec. of water). 
 
 To test for benzol, add a few drops of the distillate to a small quantity of 
 a mixture of concentrated HNO, and concentrated H,SO,, and heat cautiously. 
 The characteristic odor of nitrobenzol will be noted if benzol is present. 
 
 If the thinner is apparently all mineral spirits, no further examination 
 is necessary. 
 
 PERCENTAGE OF PIGMENT 
 
 Strain a portion of the well-mixed sample through a No. 80 sieve to remove 
 any skins and weigh accurately about 15 g. of the strained paint in a weighed 
 centrifuge tube. Add 20 to 30 ce. of “extraction mixture” (see “Reagents”), 
 mix thoroughly with a glass rod, wash the rod with more of the extraction 
 mixture and add enough of the reagent to make a total of 60 cc. in the 
 tube. Place the tube in the container of a centrifuge, surround the tube 
 with water, and counterbalance the container of the opposite arm with a 
 Similar tube, or a tube with water. Whirl at a moderate speed until well 
 Settled. Decant the clear supernatant liquid, repeat the extraction twice 
 with 40 ec. of extraction mixture and once with 40 cc. of ethyl ether. After 
 drawing off the ether, set the tube in a beaker of water at about 80° ©. or on 
 top of a warm oven for 10 minutes, then in an oven at 105 to 110° C. for two 
 
 * A.S.T.M. Standards Adopted in 1926 
 
682 Analysis of Paints 
 
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 hours. Cool, weigh, and calculate the percentage of pigment. Grind the pig- 
 ment to a fine powder, pass through a No. SO sieve to remove any skins, and 
 preserve in a stoppered bottle. = 
 ’ an 
 PERCENTAGE OF NON-VOLATILE VEHICLE . 
 Add together the percentages of water, of volatile thinner, and of pigment, oe 
 and subtract the sum from 100. Report the remainder as non-volatile vehicle, * 
 ‘ 
 TESTING NON-VOLATILE VEHICLE a 
 (a) Preparation of fatty acids. = 
 
 To about 25 g. of the paint in a porcelain casserole, add 15 cc. of aqueous © 
 sodium hydroxide (see “Reagents”) and 75 ce. of ethyl alcohol, mix and heat 
 uncovered on a steam bath until all volatile thinner is driven off and saponifi- 
 cation is complete. Add 100 cc. of water, boil, add H,SO, (sp. gr. 1.2) (8 to 
 10 cc. in excess), boil, stir, and transfer to a separatory funnel to which 
 some water has been previously added. Draw off as much as possible of 
 the acid aqueous layer and any insoluble or precipitated matter, wash once os 
 with water, then add 50 cc. of water and 50 cc. of ethyl ether. Shake very 
 gently with a whirling action to dissolve the fatty acids in the ether, but not 
 so violently as to form an emulsion. Draw off the aqueous layer and wash ~ 
 the ether layer with one 15-cc. portion of water and then with 5-cc. portions 
 of water until free from sulfuric acid. Then draw off.the water layer com- zi 
 pletely. Transfer the ether solution to a dry flask and add 25 to 50 g. of 
 anhydrous sodium sulfate. Stopper the flask and let stand wth occasional a 
 shaking at a temperature below 25° C. until the water is completely removed Be 
 from the ether solution, which will be shown by the solution becoming per- 
 fectly clear above the solid sodium sulfate. Decant this clear solution, if 
 necessary, through a dry filter paper into a dry 100-ce. Erlenmeyer flask. 
 Pass a rapid current of dry air (pass through a CaCl, tower) into the mouth 
 of the Erlenmeyer flask and heat to a temperature below 75° C. on a dry hot 
 plate until the ether is entirely driven off. It is important to follow all of © 
 the details, since ether generally contains alcohol, and after washing with 
 water always contains water. It is very difficult to remove water and alcohol 
 by evaporation from fatty acids, but the washing of the ether solution and 
 subsequent drying with anhydrous sodium sulfate removes both water and — 
 alcohol. Ether, in the absence of water and alcohol, is easily removed from 
 fatty acids by gentle heat. If the pigment settles out rapidly in a sample 
 of the paint on standing so that sufficient vehicle can be poured off; or, if a 
 sufficient vehicle is obtained by centrifuging the paint, it will be advan-— 
 tageous to saponify this separated vehicle and liberate and prepare the fatty 
 acids as described. 
 
 The fatty acids prepared as above should be kept in a stoppered flask and 
 examined at once. : 
 
 (b) Test for mineral oil and other unsaponifiable matter. 
 
 Place 10 drops of the fatty acids Method (a), in a 50-cc. test tube, add 5 ce 
 of alcoholic soda (see “Reagents’’), boil vigorously for five minutes, add 40 cc. 
 of water, and mix: a clear solution indicates that not more than traces of — 
 unsaponifiable matter are present. 
 
 (c) Iodine number of fatty acids (Note 2). 
 
 Place a small quantity of the fatty acids Method (a), in a sinall weighing — 
 burette or beaker. Weigh accurately. Transfer by dropping about 0.15 g. = 
 
Analysis of Paints : 683 
 
 (0.10 to 0.20 g.) into a 500-cc. bottle having a well ground glass stopper, or an 
 Erlenmeyer flask having a specially flanged neck for the iodine test. Reweigh 
 the burette or beaker and determine the amount of sample used. (If desired 
 the sample may be weighed in a small wide-mouthed vial and the vial con- 
 taining the weighed sample placed in the bottle or flask.) Add 10 cc. of 
 chloroform. Whirl the bottle or flask to dissolve the sample. Add 10 ce. of 
 chloroform to two empty bottles or flasks like that used for the sample. Add 
 to each bottle or flask 25 cc. of the Wijs solution (see “Reagents’”) and let 
 stand with occasional shaking for one hour’in a dark place at a temperature 
 of from 21 to 23° C. Add 10 ce. of the 15-per-cent potassium iodide solution 
 and 100 cc. of water, and titrate with standard sodium thiosulfate solution. 
 (see “Reagents’”), using starch as indicator. The titrations on the two 
 blank tests should agree within 0.1 ec. From the difference betwene the aver- 
 age of the blank titrations and the titration on the sample and the iodine 
 value of the thiosulfate solution, calculate the iodine number of the sample 
 tested. (Iodine number is centigrams of iodine to 1 g. of sample.) 
 
 (ad) Rosin. 
 
 Liebermann-Storch Test.*—To about 1 g. of the fatty acids add 15 cc. of 
 acetic anhydride and shake until solution is complete. Pour a few drops of 
 this solution on a white porcelain plate (a crucible cover serves well) and 
 add a drop of H.SO, (sp. gr. 1.53). <A fugitive violet color indicates rosin. 
 
 Halphen-Hicks Test.;—Place about 1 g. of the fatty acids in a cavity of 
 an ordinary porcelain color-reaction plate. Fill the cavity with a solution of 
 one part by volume of phenol dissolved in two parts by volume of carbon 
 tetrachloride. Stir the mixture. Fill another cavity of the porcelain plate 
 with a solution of one part by volume of bromine and four parts by volume 
 of carbon tetrachloride. Cover the whole plate with an inverted watch glass. 
 If rosin is present the bromine fumes develop very soon an indigo blue color 
 which persists for some time. 
 
 ANALYSIS OF PIGMENT 
 
 (a) Qualitative Analysis. 
 
 A complete qualitative analysis, following the well-established methods, 
 should be made and the quantitative scheme modified as required. Add acetic 
 acid slowly to the pigment until all carbonate is decomposed (noting whether 
 any hydrogen sulfide is evolved) ; then add a large excess of acid ammonium 
 acetate solution (see “Reagents”), boil, filter, and test the filtrate for metals 
 other than lead and zine (especially calcium and barium). The absence of 
 calcium in this filtrate indicates that the extending pigments contain no ¢al- 
 cium carbonate or calcium sulfate; the absence of barium indicates that the 
 extending pigments contain no barium carbonate (Note 5). Wash the matter 
 insoluble in acid ammonium acetate solution with another portion of this 
 solution, and finally with hot water. This insoluble matter is dried, ignited, 
 and tested for siliceous matter, barium sulfate, and titanium compounds. To 
 test for the latter, place a small amount of the insoluble matter, or of the 
 original sample (about 0.5 g.), in a 250-ce, Pyrex glass beaker; add 20 cc. 
 
 * “Chemical Technology and Analysis of Oils, Fats and Waxes,” by J. Lew- 
 
 kowitsch, Vol. 1, p. 623 (1921). 
 7 Jowrnal of Industrial and Engineering Chemistry, Vol. 3, p. 86 (1911). 
 
684 Analysis of Paints 
 
 = 
 
 of concentrated H,SO,4 and 7 to 8 g. of ammonium sulfate. Mix well, and boil ca 
 for a few minutes. A residue denotes the presence of silica or siliceous matter. 
 Cool the solution, dilute with 100 cc. of water, heat to boiling, settle, filter, 
 
 wash with hot 5-per-cent sulfuric acid until free from titanium. The residue 
 may be tested for lead, barium, and silica. Add hydrogen peroxide to a — 
 
 small portion of the filtrate; a clear yellow-orange color indicates the pres- 4 
 ence of titanium. Boil another portion of the filtrate ih metallic tin or = 
 
 zinc; a pale blue to violet coloration indicates titanium. . ‘Treat another por- A 
 
 tion (about 1 g.) of the pigment with 20 cc. of HCl (1:1) and note whether 4 F 
 
 any H,S is evolved; boil the solution for about 5 minutes, add about 25 cc. 
 
 of hot water, filter, and wash with hot water. ; Render a small portion of the = 
 filtrate alkaline with NH,OH, acidify with HCl, and add a little BaCl, © 
 
 solution; a white precipitate (BaSO,) indicates the presence of a soluble = 
 
 sulfate.2 To another portion of the filtrate add a little H,SO,; a white pre- 
 cipitate indicates the presence of lead, soluble barium or both (some CaSO, 
 may also separate) ; filter, wash to remove free acid, and treat the precipi- ¢ 
 tate with a few drops of KI solution; the formation of yellow PbI, indicates c: 
 the presence of lead. The white precipitate may also be treated with H,S8 = 
 water; the formation of black PbS indicates the presence of lead.3 To another 
 portion of the original filtrate add NH,OH until alkaline, render slightly acid 
 with acetic acid, heat to boiling, and add a little K,Cr,O, solution; a yellow _ 
 
 or orange-yellow precipitate indicates the presence of lead, soluble barium £ 
 
 or both. “To another portion of the original filtrate add a few drops of Zz 
 K,Fe(CN), solution; a white precipitate with a bluish tinge indicates the 
 presence of zine. Pass into the remaining portion of the original filtrate a 
 current of H,S for 5 to 10 minutes, add an equal volume of water and pass — 
 
 H.S into the solution for about 5 minutes; filter, wash with H,S water = 
 then digest the precipitate with ammonium polysulfide, filter, acidify the zg 
 filtrate with HCl and warm; the presence of antimony is indicated by the ~ 
 
 separation of an orange colored precipitate. The filtrate from the H.S pre- 
 cipitate may be tested for barium, calcium, and magnesium in the usual ~ 
 manner, | i 
 (b) Quantitative Analysis. 
 (1). Single Pigments: 
 If the sample is a single pigment, follow the method described in the 
 
 Standard Methods of Routine Analysis of White Pigments (Serial Designa- 
 
 tion: D 34) of the American Society for Testing Materials* for eS. particular — : 
 pigment in hand. a 
 (2) Mixed or Composite Pigments ; - 
 Moisture (Note 3) (Matter Volatile at 105-110° C.).—Place 1 to 2 g. of — 
 
 the sample in a wide-mouth, short weighing tube provided with glass stopper. — 
 
 Heat with the stopper removed for 2 hours at a temperature between 105 & 
 and 110° C. Insert the stopper, cool, and weigh. Calculate the loss in oe 
 weight as moisture (matter volatile at 105 to 110° C.). 
 
 Loss on Ignition.—Ignite 1 g. of the pigment in a porcelain crucible over .. 
 a Meker burner to constant weight (Note 4). = 
 
 Insoluble Matter.—Moisten 1 g. of the sample with a few drops of alcohol, 
 cover, add 40 cc. of HCl (1:1), boil gently for 5 to 10 minutes. Wash off 7 
 
 * 1924 Book of :A.S.T.M. Standards. 
 
Analysis of Paints 685 
 
 cover, evaporate to dryness, and heat at about 150° C. for one-half to one 
 hour to dehydrate the residue. Moisten the residue with 4 cc. of concen- 
 trated HCl, allow to stand a few minutes, dilute with 100 cc. hot water, boil 
 a few minutes, filter hot through paper, wash with hot water (till washings 
 give no test for lead and chlorine). Ignite the paper and residue in a plati- 
 num or porcelain crucible, cool, and weigh total insoluble matter (Note 5). 
 (The insoluble matter may be filtered off on a Gooch crucible, washed with 
 hot water, dried at 105°C., cooled, and weighed; then ignited, cooled, and 
 weighed, when it is desired to get the loss on ignition (combined water, 
 organic matter, etc.) of same, or the insoluble matter is not to be further 
 examined.) If the sample contains titanium pigment, practically all of the 
 TiO, will be found in the insoluble matter along with BaSO, and siliceous 
 matter. The TiO, may be determined in the insoluble matter or in a separate 
 portion of the original sample by the method described in the Standard 
 Methods of Routine Analysis of Titanium Pigments (Serial Designation: 
 D 186) of the American Society for Testing Materials.* To determine BaSQ,, 
 mix the ignited insoluble matter with about 10 times its weight of anhydrous 
 sodium carbonate (grinding the mixture in an agate mortar if necessary), 
 and fuse the mixture in a covered platinum crucible, heating about one 
 hour. Let cool, place crucible and cover in a 250-ce. beaker, add about 
 100 ce. of water, and heat until the melt is disintegrated. Filter on paper 
 (leaving crucible and cover in beaker) and wash the beaker and filter thor- 
 oughly with hot water to remove Soluble sulfates. Place the beaker con- 
 taining the crucible and cover under the funnel, pierce the filter with a glass 
 rod, and wash the residue into the beaker by means of a jet of hot water. 
 Wash the paper with hot dilute HCl (1:1) and then with hot water. Remove . 
 erucible and cover, washing them with a jet of hot water and removing any 
 adhering precipitate. Add cautiously 20 cc. of concentrated H,SO, and evap- 
 orate until fumes of H.SO, are evolved and the precipitated matter is dis- 
 solved. Cool, add cautiously, with stirring, about 100 ec. of water, and boil 
 a few minutes. Let the precipitate settle, filter on a weighed Gooch crucible, 
 wash with hot water, ignite, cool, and weigh as BaSO,. Subtract the sum of 
 the percentages of BaSO, and TiO, from the percentage of total insoluble 
 matter and report the result as the percentage of insoluble siliceous matter 
 (Note 6). 
 
 If it is desired to examine the siliceous matter, unite the filtrates from the 
 Na,CO, fusion and the BaSO, precipitate, acidify with HCl, evaporate to 
 dryness, and proceed as in a Silicate analysis, taking cognizance of any 
 TiO, that may be found, if titanium pigment were originally present. 
 
 Total Lead (Antimony ).—Unite the filtrate and washings (total volume 
 150 to 200 cc.) from the total insoluble matter, pass H.S into the solution 
 until it is saturated, add an equal volume of water, and again saturate with 
 H.S. Filter, wash with water containing a little hydrogen sulfide, dissolve 
 in hot HNO, (1:3), washing the paper with hot water; add 10 to 20 ce. 
 of H,SO, (1:1), evaporate until copious fumes of sulfuric acid are evolved ; 
 cool, add about 75 cc. of water, and then about 75 cc. of 95-per-cent ethyl 
 alcohol. Stir, let settle, filter on a Gooch crucible, wash with dilute alcohol, 
 
 *A.S.T.M. Standards Adopted in 1925 
 
686 Analysis ot Paints 
 
 aa 
 
 dry in an oven at 105 to 110° C.; or, ignite gently in a radiator* or muffle, — 
 
 cool, and weigh as PbSO, Calculate to PbO (Note (Se 
 
 If the pigment contains antimony, filter and wash the sulfide precipitate — 
 as above; then wash the precipitate with a fine jet of H,O from the paper — 
 
 into a porcelain dish or casserole, add 25 ce. of ammonium polysulfide (see 
 “Reagents”), cover the vessel, and warm the mixture at 40 to 60° C. for 10 
 to 15 minutes with frequent stirring. Wash off cover, filter through the paper 
 
 used in the first case, and wash with 2 to 3-per-cent Na,S or (NH,).S solution, | 
 
 A RT Wy ais arin Ay 
 
 Discard the filtrate. Dissolve the residue in hot dilute HNO, (1:3), and — 
 
 determine the lead as PbSO,, as described above. Or, the original sulfide — 
 precipitate may be discarded and the lead determined on a separate portion 
 
 of the pigment as follows: To 1 g. of the sample in a covered beaker, add 
 40 ec. of HCl (1:1) and boil gently for 5 to 10 minutes. Wash off cover and 
 
 evaporate to dryness. Moisten the residue with a few drops of HCl, add 
 
 about 50 cc. of hot water, boil a few minutes, filter hot through paper, and 
 
 wash with hot water until washings give no test for lead. (If the sample 
 contains no insoluble matter, the filtration is omitted.) To the filtrate add 
 
 20 ce. of H.SO, (sp. gr. 1.84) and evaporate until dense white fumes of 
 H,SO, are copiously evolved. Allow to cool, but not below 60° C., and then 
 add slowly 50 cc. of water while the solution is agitated. Heat to boiling 
 for several minutes in order to insure complete solution of antimony sulfate. 
 Allow the PbSO, to settle out until the supernatant liquid is clear, not 
 
 letting the temperature fall below 60° C. If the liquid does not clear quickly 
 
 it must be heated longer. When clear, pour the solution through a weighed 
 porcelain Gooch crucible with asbestos mat, decanting the solution as com- 
 pletely as possible without allowing more than a very small amount of PbSO, 
 to go over into the crucible. Now add 10 cc. more of H,SO, (sp. gr. 1.84) 
 
 to the PbSO, in the original beaker, and boil for several minutes. Cool, add + 
 slowly 30 cc. of water, and again heat to boiling for a few minutes; allow — 
 
 iB 
 = 
 % 
 
 the solution to cool to about 60° C. and completely transfer the PbSO, to the — 
 Gooch crucible. Wash with “lead acid” (see “Reagents’”) to remove soluble — 
 
 sulfates and finally wash free of acid with dilute alcohol (equal parts of — 
 
 ethyl alcohol or denatured alcohol and water). Dry in an oven at 105 to 
 
 110° C., or, ignite gently in a radiator or muffle. Calculate to PbO. Or, — 
 
 determine as chromate as described below. 
 
 If soluble compounds of barium or calcium are present, BaSO, and CaSO, 2 
 will be included with the PbSO,. If soluble SiO, is present, it will also be 
 
 included with the PbSO,. In such cases, the PbSO, precipitate after washing 
 
 with dilute alcohol may be dissolved in acid ammonium acetate (see — 
 
 ‘“Reagents”) and the lead determined as PbCrO,, as described below. For — 
 ordinary work, the amount of BaSO, dissolved by the acetate treatment may — 
 
 be disregarded. 
 
 If the pigment contains no soluble antimony, barium, or calcium compounds, 
 the lead may be determined directly on the original pigment, as follows: © 
 To 1 g. of the sample in a covered beaker, add 25 cc. of HNO, (1:1), and — 
 boil gently a few minutes. Wash off cover, evaporate to dryness on a steam i 
 bath, moisten with HNO,, add hot water, and heat a few minutes. Filter — 
 and wash wtih hot water until washings are lead-free. Add 10 to 20 cc. of — 
 
 * U. S. Geological Survey Bulletin 700, p. 33 (1919). 
 
Analysis of Paints 687 
 
 H.SO, (1:1) to the clear solution, evaporate and determine lead as PbSO,. 
 as above described. 
 
 In the absence of soluble compounds of antimony, iron, aluminum, and 
 barium, the following procedure may be used: Treat 1 g. of the original 
 pigment with 25 cc. of HNO, (1:1) and proceed as above. To the clear 
 solution, diluted to 200 cc. add NH,OH in slight excess, acidify with acetic 
 acid, and add 4 to 6 cc. more of this acid; heat to boiling and add 10 to 15 ce. 
 of a 10-per-cent solution of K,Cr.O,. Heat until the yellow precipitate assumes 
 an orange color, let settle and filter on a weighed Gooch crucible, wash by 
 decantation until the washings are colorless, finally transferring all of the 
 precipitate. Then wash wth 95-per-cent ethyl alcohol and then with ether; 
 dry to constant weight at 110° C., cool, and weigh PbCrO4. Calculate to PbO. 
 
 Antimony Oxide.—Transfer 0.3 g. of a straight antimony oxide pigment, 
 or 0.5 g. of a mixed pigment, to a 500-cc. Pyrex Erlenmeyer flask, add 15 ce. 
 of water and 25 ce. of concentrated HCl (sp. gr. 1.19). Cover with a watch 
 glass, warm on the steam bath 10 to 15 minutes to dissolve the antimony 
 oxide, wash off cover, add 250 cc. of water, and 15 ec. of concentrated H.SO, 
 (sp. gr. 1.84). Boil 2 minutes, cool to 10 to 15° C. and titrate to a faint pink 
 tint with 0.1 N KMnOy, solution (see ‘“Reagents’’). Calculate to SbyOz. 
 
 The above procedure gives only the antimony in the ows condition. The 
 following method gives the total antimony (ows and ic forms): Transfer 
 0.5 g. of a straight antimony oxide pigment, or 0.5 g. of a mixed pigment, 
 to a 500-cc. Pyrex Erlenmeyer flask, add 15 ec. of H,SO, (sp. gr. 1.84), 10 g. 
 of K,SO,, and a 9-cm. filter paper (to furnish carbon to act as a reducing 
 agent). Place a funnel in the neck of the flask, and heat until the solution 
 becomes colorless. Cool, wash off the funnel, dilute to 250 ec. with water, 
 add 20 ec. of concentrated HCl, and boil 2 minutes; cool to 10 to 15° C., and 
 titrate to a faint pink tint with 0.1 N KMn0O, solution. 
 
 Note.—If the digestion with H,SO, and K,SO, (plus filter paper) is con- 
 tinued after the solution becomes colorless, some of the antimony may be 
 oxidized from the ows to the ic condition. In such cases, cool, wash off the 
 funnel, dilute to 100 cc. with water, add 1 to 2 g. of Na.SO, and boil until all 
 of the SO, is expelled. This is shown when no blue color is obtained with 
 starch-iodate paper (see “Reagents’”) ; the volume will be reduced about one- 
 half. Dilute to 250 cc. with water, add 20 cc. of HCl (sp. gr. 1.19), and boil 
 2 minutes; cool to 10 to 15° C., and titrate to a faint pink tint with 0.1 NV 
 KMnO, solution. Calculate total Sb to Sb,O,;. Subtract the Sb,O, found by 
 the procedure given in the preceding paragraph from the total Sb.O, and 
 calculate the residual Sb,O, to Sb.O,. 
 
 Antimony Oxide (in the presence of appreciable amounts of iron).—Treat 
 1 g. of the mixed pigment, or 0.3 g. of a straight antimony oxide pigment. in a 
 covered 250-cc. beaker with 5 cc. of water and 20 ce. of HCl (sp. gr. 1.19); 
 heat on the steam bath for 15 minutes, cool, wash off cover, add 8 g. of tartaric 
 acid and 100 ce. of hot water, and digest a few minutes. Filter, catching the 
 filtrate in a 500-cc. Pyrex Erlenmeyer flask: wash thoroughly with hot water, 
 dilute to 300 ce. with hot water, and pass in H.S until the precipitation is 
 complete. (If the sample contains no insoluble matter, dissolve directly in a 
 900-ce. Pyrex Erlenmeyer flask. add tartaric acid. dilute. and pass in H.S.) 
 Filter. wash with water containing H.S until free from HCl, return paper 
 
688 Analysis of Paints 
 
 —— emacs 
 
 and precipitate to the Erlenmeyer flask, add 15 ce. of H,SO, (sp. gr. 1.84) 
 and 10 g. of K.SO,, place a funnel in the neck of the flask, and heat until the 
 solution is colorless. Cool, wash off the funnel, dilute to about 250 cc. with 
 water, add 20 cc. of HCl (sp. gr. 1.19), boil for 2 or 3 minutes, cool to about 
 10° C., and titrate to a faint pink tint with 0.1 N KMn0Q, solution (see 
 “Reagents”). Calculate the total antimony to Sb,O. 
 
 Note.—If the digestion with H,SO, and K,SO, (plus filter paper) ‘is con- 
 tinued after the solution becomes colorless, some of the antimony may be 
 oxidized from the ous to the ic condition. In such cases, cool, wash off the 
 funnel, dilute to 100 cc. with water, add 1 to 2 g. of Na,SO, and boil until all — 
 of the SO, is expelled. This is shown when no-blue color is obtained with | 
 starch-iodate paper (see ‘“Reagents”) ; the volume will be reduced about one- 
 half. Dilute to 250 cc. with water, add 20 ce. of HCl (sp. gr. 1.19), and boil 2. 
 minutes; cool to 10 to 15° C., and titrate to a faint pink tint with 0.1 WV 
 KMnO, solution. 
 
 Soluble Barium.—Boil the combined filtrate and washings, reduced in 
 volume by evaporation if need be, from the PbS precipitate (Total Lead) to 
 expel H.S. Add a slight excess of H,SO, (1:4) over the amount required to 
 precipitate the barium, heat to boiling, let stand on a steam bath about one 
 hour, filter on a weighed Gooch crucible, wash with hot water, dry, ignite, 
 cool, and weigh BaSO, (Notes 5 and 8). Calculate to BaO. 
 
 Alumina (Fe,O;, TiO., P,O,).—Boil the filtrate from the PbS to expel HS, 
 add a few drops of HNO,, and continue the boiling a few minutes to oxidize - 
 any iron that may be present. In case soluble barium was present, use the 
 filtrate from that determination. To the solution containing at least 5 g. of 
 NH,Cl per 200 cc. of solution, or an equivalent amount of HCl, add a few 
 drops of methyl red (0.2-per-cent alcoholic solution) and heat just to boiling. 
 Carefully add dilute NH,OH drop by drop until the color of the solution 
 changes to a distinct yellow. Boil the solution for one to two minutes and — 
 filter at once. Wash the precipitate thoroughly with hot 2-per-cent NH,Cl~ 
 solution (Note 9). Ignite the precipitate, cool, and weigh as AlgOg, (Note 10y4 
 
 Total Zinc.—(a) To the combined filtrate and washings from the alumina : 
 precipitate, add sufficient NH,Cl to give 5 g. per 100 ce. of solution, and then : 
 add 1 g. of ammonium acetate.* x 
 
 Render slightly acid with acetic acid and pass in a current of H,S to ~ 
 saturation. Allow the precipitate to settle completely, filter on paper, and — 
 wash with a 2-per-cent solution of acetic acid saturated with H,S. Transfer — 
 the precipitate and filter to the vessel in which the precipitation was effected, ‘ 
 add 30 ce, of water and 10 ce. of concentrated HCl, heat until all zine is in ~ 
 solution, add 200 cc. of water and a small piece of litmus paper; add strong — 
 NH,OH until slightly alkaline, render just acid with HCl, then add 3 ce, of 
 concentrated HCl, heat nearly to boiling, and titrate with standard potassium — 
 ferrocyanide solution as in standardizing that solution (see “Reagents”). # 
 
 (b) Zine may be determined directly on the original sample as follows 
 (Note 11): Weigh accurately about 1 g. (or an amount that will give a 
 purette reading approximately equal to that obtained in the standardization) é 
 
 i 
 oe 
 
 *B. A. Gooch, “Represantative Procedures in Quantitative Chemical 
 Analysis,” 1st Ed., p. 107. 
 
Analysis of Paints 689 
 
 of the pigment, transfer to a 400-cc. beaker, add 30 cc. of HCl (1:2), boil 
 a few minutes, add 200 ce. of water and a small piece of litmus paper; add 
 strong NH,OH until slightly alkaline, render just acid with HCl, then add 
 8 ce. of concentrated HCl, heat nearly to boiling, and titrate with standard 
 K,Fe (CN), solution as in standardizing that solution (see ‘“Reagents”). 
 
 (c) When iron is present, total zinc may be determined directly on the 
 original sample as follows (Note 11): Weigh accurately about 1 g. (or an 
 amount that will give a burette reading approximately equal to that obtained 
 in the standardization) of the pigment, transfer to a 250-cc. beaker, moisten 
 with alcohol, add 30 ce. of HCl (1:2), boil for 2 or 3 minutes, and add about 
 100 cc. of water. Add about 2 g. of NH,Cl, make slightly alkaline with NH,OH, 
 heat to boiling, let settle on steam bath, filter into a 400-cc. beaker and wash 
 the residue once with hot water. Remove the 400-cc. beaker and pour dilute 
 HCl on the residue, catching the filtrate therefrom in the 250-cc. beaker, wash 
 a few times with hot water. Add to this filtrate 1 g. of NH,Cl and make 
 slightly alkaline with NH,OH, boil, let settle, filter on paper used for first 
 filtration, and wash thoroughly with hot water, catching the filtrate and 
 washings in the 400-cc. beaker containing the first filtrate. Add a small piece 
 of litmus paper, acidify with HCl, add 8 ce. of concentrated HCl, heat nearly 
 to boiling, and titrate with standard K,Fe(CN), as above. 
 
 (d@) With pigments containing ZnO and ZnS the ZnO may be determined 
 as follows: Weigh accurately 2.5 g. of the pigment, transfer to a 250-ce. 
 graduated flask, moisten with a few drops of alcohol, add about 200 ce. of 
 2 to 3-per-cent acetic acid, shake vigorously and let stand for 30 minutes at 
 room temperature, shaking once every 5 minutes. Then let stand at room tem- 
 perature at least 5 hours, preferably overnight. Fill to the mark with 2 to 3- 
 per-cent acetic acid, mix, filter through a dry paper, discard the first 25 cc. and 
 transfer 100 cc. of the filtrate (corresponding to 1 g.) to a 400-cce. beaker. 
 To the clear solution add 30 cc. of HCl (1:2), 100 cc. of H.O, and a small 
 piece of litmus paper; add strong NH,OH until slightly alkaline, render just 
 acid with HCl, then add 3 cc. of concentrated HCl, heat nearly to boiling, 
 and titrate with K,Fe(CN), as above. Calculate the percentage of ZnO 
 (any ZnCO, or ZnSO, is included in the ZnO). Subtract this result from the 
 percentage of total Zn as ZnO, and calculate the difference to ZnS. 
 
 Soluble Calcium.—Heat the united filtrate and washings, reduced in volume 
 if need be, from the ZnS precipitate, to boiling, add 1 cc. of NH,OH and an 
 excess of a hot saturated ammonitim oxalate solution. Continue the boiling 
 until the precipitate becomes granular; let stand about one hour, filter, and 
 wash with hot water. Ignite, cool, and weigh as CaO (Notes 5, 12, 13); or, 
 place the beaker in which the precipitation was made under the funnel, pierce 
 the apex of the filter with a stirring rod and wash the precipitate into the 
 beaker with hot water, pour warm dilute H,SO, (1:4) through the paper 
 and wash a few times. Add about 30 ce. of dilute H,SO, (1:4), dilute to 
 about 250 cc., heat to 90° C, and titrate at once with standard (0.1 V) KMnO, 
 solution (the temperature of the solution should not be below 60° C. when 
 the end point is reached. See “Reagents’). Calculate to CaO (Notes 5, 12, 
 13). (The Fe value of KMnO, X 0.502 = CaO value. ) 
 
 Soluble Magnesium.—Acidify the filtrate from the calcium precipitate 
 With HCl, add 10 ce. of a saturated solution of Na(NH,)HPO, and NH:OH 
 drop by drop, with constant stirring. When the crystallin (NHs)MgPO, has 
 
690 Analysis of Paints 
 
 formed, add 5 ec. excess of NH,OH. Allow the solution to stand in a cool 
 
 place for not less than 4 hours, preferably overnight (Note 14) ; filter and s 
 
 wash with water containing 2.5 per cent of NH,;. Dissolve the precipitate Fe 
 
 in a small quantity of hot dilute HCl, dilute the solution to about 100 ce. 
 with water, add 1 cc. of a saturated solution of Na(NH,)HPOs« and NH,OH 
 drop by drop, with constant stirring, until the precipitate is again formed as 
 described, and then add 5 cc. excess of NH,OH. Let the precipitate stand in~ 
 
 a cool place for not less than 2 hours, filter on a Gooch crucible, wash with ~ 
 ] 
 
 = 
 
 water containing 2.5 per cent of NH,, ignite, cool, and weigh as Mg,P,0,— 
 (Note 15). Calculate to MgO. 
 
 Carbon Dioxride.—Determine by evolution with dilute acid and absorption 
 
 in soda lime or KOH solution. The method given in U. S. Geological Survey 
 
 Bulletin 700, p. 218, shows a convenient apparatus for carrying out this ; 
 
 determination. Use from 1 to 2 g. of the pigment, depending upon the prob- 
 able CO, content, following the method for the determination of carbon 
 dioxide in lime described in the Tentative Methods of Chemical Analysis of 
 Limestone, Quicklime and Hydrated Lime (Serial Designation: C 25-26 T) 
 of the American Society for Testing Materials* (Note 16). ‘ 
 Total Soluble Sulfur Compounds (Note 5).—Treat 1 g. of the pigment in 
 a 400-ce. beaker with 10 cc. of H,O, 10 ce. of strong HCl saturated with 
 
 bromine, and 5 g. of NH,Cl, digest (covered) on a steam bath for 5 minutes, % 
 
 dilute with hot water to about 200 ec., boil for 5 minutes, filter to separate 
 any insoluble matter, and wash thoroughly with hot water. Nearly neutralize 
 
 the clear solution in a covered beaker with NaOH solution, complete the — 
 neutralization with dry Na,CO, and add about 2 g. more of this reagent. — 
 
 TERRA ah Shy 
 
 Boil 10 to 15 minutes, wash off cover, let settle, filter, and wash with hot — 
 water. Re-dissolve the precipitate in HCl (1:1), reprecipitate with Na.CO, ° 
 as above, filter, and wash thoroughly with hot water. Acidify the united — 
 
 filtrates with HCl, adding about 1 cc. in excess. Boil to expel bromine, and ; 
 to the clear boiling solution add slowly with stirring.an excess of a 10-per- — 
 
 cent BaCl, solution. Let stand on a steam bath for at least 1 hour, filter > 
 
 on a weighed Gooch crucible, wash thoroughly with boiling water, dry, ignite — 
 
 4 
 
 at a dull red heat, cool, and weigh as BaSO,. This will include soluble sul- * 
 fates, SO, formed from SO, and the SO, that is formed from sulfide sulfur ie 
 
 (Note 8). 
 
 Soluble Sulfate (Note 5).—Treat 1 ¢g. of the pigment with 10 ce. of H,O 7 
 and 10 ce. of concentrated HCl and 5 g. of NH,Cl. Boil until H.S is expelled, — 
 adding more HC] (1:1) if necessary; dilute with hot water to about 200 cec., — 
 
 Pa SF a a 
 
 boil for 5 minutes, filter to separate any insoluble matter, and wash thor- a 
 oughly with hot water. Nearly neutralize the clear solution with NaOH solu- & 
 tion and make a double precipitation with Na.CO,, as in preceding method, — 
 
 finally weighing as BaSO,, as described above (Note 8). 
 Sulfide Sulfurt (Note 17).—Place 0.5 to 1 g. of the pigment in a flask with 
 about 10 g. of “feathered” or mossy zine, add 50 ec. of water; insert @ 
 
 stopper carrying a separatory funnel and an exit tube. Run in 50 ce. of 
 
 concentrated HCl from the funnel, having previously connected the exit tube — 
 to two absorption flasks in series; the first flask contains 100 cc. of alkaline ~ 
 
 * See p. 290 Footnote. A.S.T.M. 1926. 
 + Evolution Method of W. G. Scott, “White Paints and Painting Materials,” 
 p. 257; see also Blair, ‘“‘The Chemical Analysis of Iron.” 
 
Analysis of Paints 691 
 
 lead-nitrate solution (see “Reagents’’), the second flask, 50 ce. of the same 
 solution as a Safety device. After all of the acid has run into the evolution 
 flask, heat slowly, finally boiling until the first appearance of steam in the 
 first absorption flask. Disconnect, let the lead sulfide settle, filter, wash 
 with cold water, then with hot water till neutral to litmus paper and wash- 
 ings give no test for lead. Dissolve the PbS precipitate in hot, dilute HNO, 
 and determine the lead as PbSO:. Calculate to S. For very rapid work, the 
 evolved H.S may be absorbed in an ammoniacal CdCl, or ZnSO. solution 
 (see “Reagents”) contained in 2 flasks connected in series, the contents of 
 the absorption flasks washed into a vessel with cold water and diluted to 
 about one liter, acidified with concentrated HCl and titrated with standard 
 potassium iodate solution (see “Reagents’’), using starch indicator (see 
 “Reagents’’). 
 
 Sulfur Dioxide (Note 18).—Transfer 10 g. of the pigment to a suitable 
 flask, insert a stopper fitted with a separatory funnel and a spray trap delivery 
 tube (Note 19), and attach the latter to a condenser. Place about 150 ce. 
 of HCl (1:3) in the funnel, the stopcock being closed (Note 20), connect 
 the other end of the condenser with a delivery tube which passes through 
 a 2-hole stopper and extends nearly to the bottom of an absorption flask; 
 through the other hole of the stopper connect a tube or flask to serve as a 
 safety device. Place 25 cc. of 0.05 N iodine solution (see “Reagents”) in the 
 absorption flask (dilute with water if need be) and 20 ce. of 10-per-cent KI 
 solution in the safety tube; fit stopper in the absorption flask. Open the 
 stopcock and allow the acid to slowly enter the flask. Before all of the acid 
 is admitted, air (washed with NaOH solution) is forced through the top of 
 the separatory funnel (about 2 bubbles per second in the KI solution). Boil — 
 the solution 3 minutes with the air passing through, then remove the source 
 of heat and pass air through for 30 minutes. Disconnect the absorption 
 vessels, wash the KI solution into the iodine solution, and titrate at once with 
 0.05 N Na,S,O, solution, using starch indicator. Run a blank determination 
 in exactly the same manner except for the omission of the pigment. Subtract 
 this figure from the previous one and calculate the final result. to SO, 
 (1 ec. 0.05 N I = 0.0016 g. SO,). 
 
 Matter Soluble in Water.—Transfer 2.5 g. of the pigment to a graduated 
 250-ce. flask, add 100 cc. of water, boil for 5 minutes, cool, fill to mark with 
 water, mix, and allow to settle. Pour the supernatant liquid through a dry 
 filter paper and discard the first 20 cc. Then evaporate 100 cc. of the clear 
 filtrate to dryness in a weighed dish, heat for one hour at 105 to 110° C., 
 cool, and weigh. Calculate the percentage. The nature of this may be deter- 
 mined by further examination, as the percentages of SO, and CaO may be 
 indicative. 
 
 NOTES 
 
 1. A convenient apparatus for this determination is shown in Fig. 1 (b) 
 
 of the Standard Method of Test for Water in Petroleum Products and Other 
 
 Bituminous Materials (Serial Designation: D 95) of the American Society for 
 Testing Materials.* 
 
 2. If appreciable amounts of resin or of unsaponifiable matter are found 
 to be absent in the vehicle of a paint, the iodine number of the fatty acids 
 gives the best indication (though not proof) of the presence of linseed oil. 
 
 * 1924 Book of A.S.T.M. Standards. 
 
692 Analysis of Paints 
 
 a 
 
 An iodine number of less than 175 (Wijs) for the fatty acids is an indication 
 that the non-volatile vehicle was not pure linseed oil. 
 
 3. On an extracted and dried pigment, this determination is of little value, 
 If the original paint contained gypsum, a part of the combined H,O of the 
 latter will be driven off in the drying of the extracted pigment and in the 
 “moisture” determination. 
 
 4. This determination may serve as a rough or approximate check in Many 
 cases on the CO,, H,O, ete. 
 
 5. If the original sample contained BaCOg and PbSO4, CaSO, or other 
 soluble sulfate. the so uble Ba will ferm with the soluble sulfate a precipitate 
 of BaSO: which will be determined as “insoluble matter.” If the sample 
 contained SrSO, cr SrCO,, some SrSO, may be counted as BaSO,, some Sr 
 will count as soluble barium. and some may be counted as CaO. This element 
 is not separated, as it probably will not be encountered, or will be present as 
 an impurity in the Ba and Ca compounds. 
 
 6. Any soluble Al,O, (Fe,O,) and in most cases MgO, and sometimes some 
 CaO, come from the siliceous pigment used. MgO generally denoted the 
 presence of asbestine. : 
 
 7. It is not possible to determine the amount of basic lead carbonate and 
 lead sulfate when carbonates or soluble sulfates of other metals, such as 
 calcium, are present. Also neither basic lead carbonate nor basic lead sulfate 
 are definite compounds, 
 
 8. This will include any BaSO, that may have been dissolved as such. The 
 weighed precipitate should be tested for CaSO, and if present, it should be 
 removed by treating with hot dilute HCl, filtering, washing, igniting, and again 
 weighing. 
 
 9. For very accurate work, or when the precipitate is large, the precipitate 
 should be dissolved in HCl (1:1) and the precipitation repeated. 
 
 10. This precipitate may also contain Fe,O;, TiO,, and P,O;. 
 
 = yet Fist 
 
 11. If the sample contains antimony, it should be precipitated by H,S in the — 
 
 hot acid solution, filtered off, washed, and the filtrate neutralized, etc., for zinc. 
 The H.S precipitate may also contain PbS. If no sulfide separation is made, 
 any cadmium present will be counted as zine. 
 
 12. Care must be exercised in this washing, as 1000 ce. of boiling water 
 will dissolve over 0.01 g. of CaC,O,. 
 
 13. For more accurate work, the CaC,O, precipitate should be ignited, 
 
 cooled, cautiously moistened with water, redissolved in HCl and the solution — 
 
 diluted to 100 cc. Then NH,OH should be added in slight excess, the liquid 
 boiled, and filtered and washed if a precipitate appears. Then reprecipitate 
 
 the Ca with NH,OH and (NH,).C,0, as above, filter, wash, ignite, cool, and 
 
 weigh; or, titrate as described. 
 
 14. The less the amount of magnesium present, the longer the precipitate 
 must be allowed to settle. 
 
 15. If the sample contained manganese, it will be caurht in large part with 
 
 the Mg.,P.0,. If desired, Mn may be determined by dissolving the Mg.P.0, $ 
 
 in HNO, and applying the bismuthate method. 
 
 16. If the sample is high in sulfide, e. g.. contains a high percentage of | 
 lithopone, grind 1 to 2 g. of the pigment with dry K.Cr.O,. transfer to the © 
 evolution flask, add 50 cc. of water, and run in H.SOs (1:1) from the sep- — 
 aratory funnel. Or, place at the front of the purifying and drying train 2 ~ 
 
 tube containing acidified CuSO, solution, KMnO, solution, or CrO; solution. 
 
 17. The percentage of sulfide sulfur can be calculated from the percentages ‘ 
 
 of total zinc and zinc soluble in 2 to 3 per cent acetic acid, assuming the sulfide 
 to be ZnS. See Method (d) under determination of zine. 
 
 18. This method is not applicable in the presence of sulfides decomposable 
 under the conditions given. 
 
 19. A Knorr CO, apparatus is very convenient. In this case, the vertical 
 
 condenser may be connected with an absorption tower containing the iodine — 
 
 solution, followed by the KI solution in a suitable tube. 
 
 20. To minimize, if not eliminate, any possible oxidation by the air, add 
 about 1g. (in one piece) of NaHCO, to the evolution flask, then add the acid 
 directly to the flask, omitting the separatory funnel and the current of air. 
 Boil the solution until about 50 cc. of distillate has passed over. 
 
Analysis of Paints 693 
 
 CALCULATIONS 
 
 The calculation of the component pigments of a mixed or combination 
 pigment may be a somewhat difficult matter. Certain assumptions must be 
 made, depending upon the complexity of the mixed pigment, as to the com- 
 position or formulas of component pigments and as to the manner in which 
 the acidic and basic radicles are combined. Add any A1,0, (Fe.O,) found 
 in the soluble portion to the siliceous matter and report the sum as “‘Insoluble 
 siliceous matter,” unless the soluble Al is high; in this case, an aluminate is 
 probably present, and the Al,O, should be reported as AI,O,. If a small 
 amount of soluble Mg is found, it should also be added to the siliceous matter. 
 If the soluble Mg is high, the presence of MgCO, is indicated, and the MgO 
 is calculated to MgCO, as pointed out below. The insoluble siliceous matter 
 reported should be based on the weight obtained on drying the total insoluble 
 matter at 105° C. if the combined H,O contained therein is to be considered. 
 
 In the absence of ZnS or TiO., report BaSO:s as BaSO,. If ZnS is present, 
 calculate the BaSO, equivalent by multiplying by 2.85; report sum of ZnS + 
 BaSO, as “lithopone.” If TiO, is present, calculate the BaSO, equivalent by 
 multiplying by 3.17; report sum of TiO, + BaSO, as “titanium pigment.” 
 Report residual BaSOs as BaSO,. If TiO, is present and BaSO, is absent ar. 
 is present in a smaller amount than would be indicated by the above factor, 
 then report TiO, as TiO., and BaSO: as BaSO,. If CaCO,, CaSO,, BaCO,, and 
 MgCO, are absent calculate CO, to basic carbonate white lead, (PbCO,), Pb 
 (OH)., and soluble SO; to PbSO:. Any excess of Pb is calculated to PbO, 
 added to the PbSO,, and the sum reported as basic lead sulfate; or, multiply 
 the sum of PbSO: + PbO by 0.058 to obtain the ZnO; add this result to the 
 PbSO, + PbO and report as basic sulfate white lead. (The ZnO factor is : 
 based on the assumption that the average composition of commercial basic 
 sulfate white lead is: 78.5 per cent PbSO,, 16.0 per cent PbO, and 5.5 per cent 
 ZnO.) Lead oxide (PbO) should not be reported except in the presence of 
 PbSO:; unless the entire analysis is reported in the elementary or oxide 
 form. 
 
 If the sample contains CO, but no soluble SO,, calculate total Pb to basic 
 carbonate white lead, (PbCO,;), Pb(OH),; calculate residual CO, to CaCoO,, 
 then to BaCO, and MgCO, if soluble Ba and Mg should be present in sufficient 
 amounts to indicate the presence of these carbonates. The CO, result will be 
 an index of this. A small amount of residual CaO is probably from the 
 Siliceous matter and should be added to the insoluble siliceous matter. 
 
 A small amount of soluble Ba may be from the CaCO, used or may be 
 due to the solubility of BaSO, if this compound is present in the original 
 pigment. This Ba may be calculated to BaSO: and added to the BaSO, found 
 in the insoluble matter. 
 
 If the sample contains soluble SO, but no CO,, calculate CaO to CaSO, 
 or CaSO, 2H,0; residual SO, to PbSO,; add residual PbO to PbSO: and report 
 Sum as basic lead sulfate; or, multiply PbSO: + PbO by 0.058 and add the 
 result to the PbSO, + PbO, and report the total as basic sulfate white lead. 
 
 If the sample contains CaCO, (MgCO,, BaCO,) and also basie sulfate 
 white lead, or CaSO, and basic carbonate white lead; or a mixture of these; 
 it is not possible to determine or calculate the amount of PbCO, or PbSOs with 
 any degree of certainty (Notes 3 and 5). The presence of appreciable amounts 
 of CaO and SO, in the water-soluble matter indicates the probable presence 
 
694 Analysis of Paints 
 
 of CaSO, in the original pigment. The following arbitrary calculations may 
 be made; calculate water-soluble SO, to CaSO, or CaSO. 2H,0, subtract this 
 SO, from total soluble SO, and calculate the remainder to PbSO,; calculate 
 residual CaO to CaCO,, and then residual CO, to (PbCO,), Pb(OH),. If there 
 is an excess of CO,, calculate to MgCO, or BaCO,, if the amounts of soluble 
 Mg and Ba indicate the probable presence of these carbonates. Add residual 
 PbO to PbSO, and calculate, as above, to basic sulfate white lead. The proce- 
 
 dure followed by the Federal Specifications Board should be noted.* 
 Report total antimony as Sb,O.. 
 
 Calculate sulfide sulfur to ZnS, subtract the Zn equivalent to the S from 
 the total Zn, then subtract the Zn required for the basic sulfate white lead, 
 and report the remainder as ZnO. 
 
 Report moisture, loss on ignition, SO., and matter soluble in water directly. 
 
 Detection of Tung Oils——Chinese wood oil may be de- 
 tected in the vehicle by mixing the oil with an equal volume of a 
 saturated solution of iodine in petroleum ether, allowing the 
 mixture to stand in direct sunlight. Under these conditions, 
 a peculiar, insoluble, spongy polymer of one of the fatty acids 
 of Chinese wood oil is shown. 
 
 Quantitative Determination of Tung Oil in Paints and Var- 
 nishes.t+—Hnough varnish to contain 1 to 2 grams Tung Oil 
 after having evaporated the thinners, is extracted with ice-cold 
 petroleum ether (40° to 60° C.) containing 40 % absolute alco- 
 hol. The extract contains the oil and is evaporated in a 
 weighed dish containing 1 to 2 gms. sand to about 10 ee. Then 
 i gm of sodium nitrate followed by 6 cc. 6N. H2S0s is added, 
 vue mass stirred, and then set aside for 30 minutes. If tung 
 oil be present a yellow spongy mass separates. Ten ce. of 
 water is now added with stirring and the liquid decanted 
 through a hardened paper. The precipitate is further washed 
 by decantation with 3 or 4 5-ce. portions of petroleum ether 
 containing 5% absolute alcohol, then with H.O, until free from 
 
 * Federal Specifications Board Specification No. 10 for “White Paint and 
 Tinted Paints Made on a White Base, Semipaste and Ready Mixed”; Bureau 
 of Standards Circular No. 89, 2d Hd., p. 2: “The total lead dissolved by dilute 
 
 acetic acid and hot acid, ammonium acetate, weighed as lead sulfate, and this * 
 
 weight multiplied by the factor 0.888 shall be considered white lead. (It is 
 not possible to determine the amount of lead carbonate and lead sulfate when 
 carbonates or sulfates of other metals, such as calcium, are present. Also 
 neither basic lead carbonate nor basic lead sulfate are definite compounds. 
 
 The factor to convert PbSO, to (PbCO,),.Pb(OH), is 0.854, to convert PbSsO, 
 to PbSO: PbO is 0.868, and to convert PbSO, to (PbSO,), PbO is 0.918. The = 
 
 arbitrary factor used under this specification is the mean of the largest and 
 smallest of these three factors. )” 
 +J. N. Goldsmith, J. Oil & Col. Chem. Assn. 78 342, (1926). ‘ 
 Fox & Bowles. Analysis of Pigments, Paints, and Varnishes 1927, p. 168. — 
 D. Van Nostrand. ¥ 
 
Analysis of Paints ees 
 
 sulfate; then with 2 or 3 5-cc. portions of absolute alcohol and 
 finally with 3 or 4 5-ce. portions of petroleum ether. The 
 precipitate may be dried in air at 100° C. and multiplied by 
 0.85 to convert to tung oil. 
 
 See also tung oil tests in Chapter XXIII. 
 
 Detection of Fish Oil—Fish oil may ordinarily be detected 
 by its odor, especially if the sample be heated and rubbed on 
 the palm of the hand. 
 
 The oldest positive method is by Marecusson and Huber* and 
 is as follows: 
 
 Ten ce. of the tatty acids of the oil are shaken in a cylinder 
 with 200 ec. Br solution containing 1 volume Br, 28 volume 
 acetic acid, and 4 volume of nitrobenzene. Fish oil and lino- 
 lenic acid yield a precipitate on one hour’s standing. Any 
 precipitate is filtered off, washed with ether, dried and 
 weighed. ‘T'o differentiate between the octabromides of fish 
 oil, fatty acids and the hexabromides of linolenic. acid, 
 the precipitate is boiled for one-half hour in benzol in an 
 Erlenmeyer flask under a reflux condenser, 2 grams of pre- 
 cipitate requiring 100 ec. benzol. The hexabromides dissolve, 
 while the octabromides do not. The melting point of the resi-. 
 due, if from fish oil, is about 200° C. The method will detect 
 about 10% of fish oil. 
 
 Tsujimoto; has developed a method for detecting fish oil 
 which depends upon the formation and precipitation of iodine 
 chlorine addition compounds of the highly unsaturated acids 
 occurring in fish oil, but not of linolenic acid. Dissolve 0.5 
 gram of the fatty acids in 10 ce. ether and add 3 5-ce. of a 1.N 
 glacial acetic acid I Cl (Wijs) solution. Keep the solution, 
 with frequent shaking, for two hours at 15 to 20° C. 
 
 If fish oil be present to the extent of 1% of Japanese sar- 
 dine oil, or 5% of herring oil, a precipitate will be formed. 
 This method has been criticized by Davidsont who states 
 that several European fish oils failed to Bye a precipitate 
 when submitted to this test. 
 
 Other Oils.—The presence of soya bean and other vegetable 
 oils is in some cases difficult to detect. The iodine numbers 
 
 * Marcusson & Huber, Seifenseider Ztg. p. 249 (1911), C. A. 5 1847 (1905). 
 + J. Soc. Chem. Ind. Japan, 29 561 (1926) C. A. 27 661 (1927). 
 ~Chem. Umschau Fette, Oile u Wachse 34 49 (1927). C. A. 27 1890 
 1927). 
 
696 Analysis of Paints 
 
 of these oils, however, are all lower than that of linseed oil. 
 Tt must be remembered, however, that the iodine number of 
 boiled linseed oil is lower than that of raw oil and that the 
 iodine number of oils extracted from many paints is usually 
 
 lower than shown by the original oil. In the presence of con- — 
 
 siderable quantities of drier, it is always advisable to extract 
 the fatty acids from oil and make the iodine determination 
 upon them. Determination of hexabromides gives best in- 
 formation as to type of oil present. 
 
 The distillate from the paint vehicle may consist of turpen- 
 tine, mineral distillates, benzol and similar solvents. The 
 presence of benzol is readily detected by adding a few drops 
 of the distillate to a small quantity of a mixture of concen- 
 trated nitric and sulphuric acids. Upon heating this mixture, 
 the characteristic odor of nitro-benzol will be recognized if 
 benzol is present. Mineral distillates from petroleum are 
 easily detected by the polymerization method given under 
 Turpentine Specifications. 
 
 ee ee ee SENT ees eT 
 
 iC renpe ‘= thy 
 
 iis on: 
 
CHAPTER XXXIX 
 
 ANALYSIS OF WHITE PIGMENTS 
 
 The methods for the analysis of white opaque as well as 
 white inert pigments, given in the preceding editions of this 
 volume, and which were used in the development of standard 
 methods are now replaced by these standard methods of the 
 A.$. T. M. which are included below, following specifications 
 for many of these products. Methods for the analysis of white 
 inert pigments are given on page 704. Following this presenta- 
 tion is given a special method for the determination of carbon 
 dioxide in white pigments, as well as a special gravimetric 
 method for the determination of zine in white pigments. 
 Other special methods are presented for determining the per- 
 centage of antimony in white pigments, see page 683. 
 
 A. 8S. T. M. STANDARD SPECIFICATIONS FOR 
 BASIC CARBONATE WHITE LEAD 
 
 1. These specifications cover what is commonly known as Basic Carbonate 
 White Lead as used as a pigment and in putty, purchased either as dry pig- 
 ment or ground in oil to form a paste. 
 
 I. MANUFACTURE. 
 
 2. (a) Dry Pigment.—The pigment shall be the product made from metallic 
 lead and shall have a composition corresponding approximately to the formula 
 2PbCO;.Pb(OH),. It shall be thoroughly washed after corroding, shall be 
 free from impurities and adulterants, and shall meet the requirements given 
 in Section 3. 
 
 (b) Paste.—The paste shall be made by thoroughly grinding the specified 
 pigment with pure raw or refined linseed oil. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) Dry Pigment.—The pigment shall conform to the following re- 
 quirements: 
 
 MaxIMuM. MINIMUM. 
 Coarse particles retained on a Standard No. 325 
 
 IIIT ICES OOTIY 5.5, gs xa e's 0 ne © adie'sie is becom wre 1.0 ee 
 SP CAEDOMALEG, DEL CONDE... test ce enone 75.0 65.0 
 Total impurities, including moisture, per cent.. 2.0 
 
 *For determining coarse particles, screen 3 in. in diameter are recom- 
 mended. The screen cloth is described as follows: No. 325 cloth of the U. 8. 
 Standard Sieve Series should be made of wire 0.036 mm. (0.0014 in.) in 
 diameter, a tolerance of 15 per cent under and 35 per cent over being allowed 
 on this diameter. The average opening between adjacent parallel wires 
 should be 0.044 mm. (0.0017 in. ) the tolerance being S per cent with the addi- 
 tional limitation that the maximum opening shall not exceed 0.044 mm. by 
 more than 90 per cent. 
 
698 Analysis of White Pigments 
 
 The color and color strength, when specified, shall be equal to that of a 
 sample mutually agreed on by buyer and seller. 
 
 (b) Paste—The paste as received shall not be caked in the container 
 and shall break up readily in oil to form a smooth paint of brushing con- 
 sistency. The paste shall conform to the followirig requirements: 
 
 MAXIMUM. MINIMUM. 
 
 Pigment (as specified above), per cent....---- 92 90 
 
 Linseed oil, per Cent.........e sere ree eerecees 10 8 
 
 Moisture and other volatile matter, per cent... OF a 
 
 Coarse particles and skins (total residue re- 
 
 tained on a Standard No. 325 screen* based 
 
 on pigment), per Cent......-ee seer ee eeeees 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 1.5 
 
 A. S. T. M. STANDARD SPECIFICATIONS FOR 
 BASIC SULFATE WHITE LEAD 
 
 1. These specifications cover the pigment commonly known as “basic sul- 
 fate” white lead. The pigment may be purchased in the dry form or ground 
 in oil to form a paste. 
 
 I. MANUFACTURE. 
 _ (a) Dry Pigment.—The pigment shall be the sublimed product prepared 
 from lead sulfide ores, and shall be free from impurities and adulteration. . — 
 (b) Paste-—The paste shall be made by thoroughly grinding the specified 
 pigment with pure raw or refined linseed oil. 
 
 Il. PROPERTIES AND TESTS. 
 3. (a) Dry Pigment.—The dry pigment shall conform to the following 
 
 requirements : 
 MAXIMUM MINIMUM 
 Coarse particles retained on a Standard No. 325 
 sereen.* per Cent... ...eeee eee e ee rerecees 4 1.0 hile 
 Lead oxide, per Cent........ eee cree eee eer ees 18.0 PUD) 
 9.0 
 
 Zine oxide, per CeNt...... eevee eeeeeecercces 
 Total impurities, including moisture, per cent.. 1.0 
 The remainder shall be lead sulfate. 
 
 The color and color strength, when specified, shall be equal to that of a 
 sample mutually agreed on by buyer and seller. 
 
 (b) The Paste.—The paste as received shall not be caked in the container 
 and shall break up readily in oil to form a smooth paint of brushing con- 
 sistency. It shall mix readily in all proportions, without curdling, with lin- 
 seed oil, turpentine, or volatile mineral spirits or any combination of these 
 
 substances. 
 
 * See footnote on page 697. 
 
 re) eee, Se 
 
 a 
 4 
 E 
 § 
 4 
 : 
 ‘ 
 
Analysis of White Pigments 699 
 
 The paste shall conform to the following requirements: 
 
 MAXIMUM MINIMUM 
 RRM TIO T COUT. y c)..s fo cic ssc en vc ccceevcscvees 91.0 89.0 
 RM UAT CL CONG. 5 eas os sw cine ccc ce ne bees én 11.0 9.0 
 Moisture and other volatile matter, per cent... 0.7 cote 
 
 Coarse particles and skins (total residue re- 
 tained on a Standard No. 325 screen,* based 
 PremisMment)y, Per Cent*® 2... 6. be we ce we le 1.5 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 A. S. T. M. STANDARD SPECIFICATIONS FOR 
 ZINC OXIDE 
 
 1. These specifications cover the pigments commonly known as “Zine 
 White,” or Zine Oxide, purchased either in the form of any pigment or ground 
 in oil to form a paste. 
 
 I. MANUFACTURE. 
 
 2. (a) Dry Pigment.—The pigment may be made by the American process 
 direct from the ore, or by the French process from spelter. The order or con- 
 tract shall state which is desired. 
 
 (b) Paste.——The paste shall be made by thoroughly grinding the specified 
 pigment with pure raw or refined linseed oil. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) Dry Pigment.—The pigment shall conform to the following re- 
 quirements: 
 
 AMERICAN PROCESS FRENCH PROCESS 
 MaAxIMUM MINIMUM MAxIMUM MINIMUM 
 Coarse particles retained on a 
 Standard No. 325 screen,* per 
 
 SU a, 2 rr 10 i 1.0 see 
 eemcroxide, per cent:.........- uke 98 ne 99 
 otal sulfur, per cent........ 0.2 ak Ape 
 Total impurities, including 
 
 moisture, per cent........ 2.0 ah 1.0 
 
 The color and color strength, when specified, shall be equal to that of a 
 Sample mutually agreed on by buyer and seller. , 
 
 (b) Paste.—The paste as received shall not be caked in the container and 
 Shall break: up readily in oil to form a smooth paint of brushing consistency. 
 The paste shail conform to the following requirements as to composition: 
 
 MAaxIMUM MINIMUM 
 MOC COCTIL. 6 os en so este ne 8 Saeed ale wae es 86 SO 
 0S O02) a 2) a 20 14 
 
 Coarse particles and skins (total residue re- 
 tained on a Standard No. 325 screen* based 
 mammemont), POT CONC. .... 66600 eece cua nnn 1.5 
 
 Moisture and other volatile matter, per cent.... 0.5 
 
 * See footnote on page 697. 
 
"i ee 
 
 700 Analysis of White Pigments 
 
 4, One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 A. 8. T. M. STANDARD SPECIFICATIONS FOR 
 LEADED ZINC OXIDE 
 
 1. These specifications cover the pigment commonly known as Leaded Zine 
 Oxide, and consisting of zine oxide with varying amounts of lead compounds, 
 purchased either as dry pigment or ground in oil to form a paste. 
 
 I. MANUFACTURE, 
 2. (a) Dry Pigment.—The pigment shall be made by the collection of the 
 fumes or dust arising from furnace operations on materials containing zinc. 
 (b) Paste-—The paste shall be made by thoroughly grinding the specified 
 pigment in pure raw or refined linseed oil. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) Dry Pigment.—The pigment shall conform to the following re- 
 quirements: att ee 
 H1GH-LEADED LOW-LEADED 
 MaximMuM MinriMuM MaxiMuM MINIMUM 
 
 Coarse particles retained on a 
 Standard No. 325 screen,* 
 
 per Ce@lt..4 <5 os sae ce ees 1.0 aie 1.0 id Ye 
 Zine oxide (ZnO) per cent.... .-. 60 cans 93 
 Water-soluble salts, per cent.. 1.0 Be 1.0 ve 
 Total impurities, including 
 
 moisture, per cent........ 1.5 oes 1.5 a 
 
 The remainder shall be normal or basic lead sulfate. 
 
 The color and color strength, when specified, shall be equal to that of a 
 sample mutually agreed on by buyer and seller. j 
 
 (b) Paste.—The paste as received shall not be caked in the container and 
 shall break up readily in oil to form a smooth paint of brushing consistency. 
 The paste shall conform to the following requirements as to composition ; 
 
 MAxIMUM MINIMUM 
 Pigment, per Cent... ss i524 se so cies 0 alo eee 88.0 Le 
 Linseed oil, per Cents. 0. icc. © cw ao ee wire ee 17.0 12.0 
 Moisture and other volatile matter, per cent... 0.5 ae eee 
 
 Coarse particles and skins (total residue re- 
 tained on a Standard No. 325 screen* based 
 on pigment), per Cent........esseeeeecrcees 1.5 he 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 A. 8S. T. M. STANDARD SPECIFICATIONS FOR 
 LITHOPONE 
 
 1. These specifications cover the pigment consisting of zine sulfide and 
 barium sulfate, commercially known as lithopone, The pigment may be pur- 
 chased in the dry form of ground in oil to form a paste. ony 
 
 * See footnote on page 697. 
 
Analysis otf White Pigments 701 
 
 I. MANUFACTURE, 
 
 2. (a) Dry Pigment.—The pigment shall be made by suitable treatment 
 of a mixture of precipitated zinc sulfide and precipitated barium sulfate. 
 
 (b) Paste.—The paste shall be made by thoroughly grinding the specified 
 pigment with pure raw or refined linseed oil. 
 
 II. PROPERTIES AND TESTS. 
 
 3. (@) The behavior on exposure to light, the mixing properties with an 
 approved vehicle, the final consistency with this vehicle and the color shall 
 be equal to, and the brightness and tinting strength (or hiding power) shall 
 be not less than, those of a sample, mutually agreed on by buyer and seller. 
 
 (b) Dry Pigment.—The dry pigment shall meet the following requirements: 
 
 MAxIMUM MINIMUM 
 Coarse particles and skins (total residue re- 
 
 tained on a standard No. 325 screen), per 
 ee ote Figs gis fein sect vives less a sv ees 1.0 
 
 ty CS 0S) MTS | iene 26.0 
 MO RICG SCT COUT. gcc. ct et ec cece wt tees 2.0 ht 
 Material soluble in water, per cent............ 0.8 Satek 
 RUMPNRINIEPEPOUTL TOTES toc, cte ns es ses ecw ccsccedicoces 98 per cent of the 
 remainder. 
 
 (c) Paste.—The paste as received shall not be caked in the container and 
 shall break up readily in oil to form a smooth paint of brushing consistency. 
 It shall mix readily in all proportions without curdling, with linseed. oil, 
 turpentine, or volatile mineral spirits, or any combination of these sub- 
 stances. The paste shall meet the following requirements: 
 
 MAXIMUM MINIMUM 
 
 SPIO T PCO itso so ives eae cde ae cee 80.0 76.0 
 IS it) a re 24.0 20.0 
 Coarse particles and skins (total residue re- 
 
 tained on a standard No. 325 screen, based 
 
 emmILG ) ACL. CONE. «cine sec sacs ee eee e's 1.5 
 
 4. (a) Paste.—One sample shall be taken at random from each lot of 1000 
 packages or less. If the packages are of such size that 1000 packages amount 
 to more than a carload, one sample shall be taken at random from each 
 earload. 
 
 (b) Dry Pigment.—Dry pigment shall be sampled by taking a portion from 
 every tenth barrel or from every one hundredth bag of the dry pigment. 
 
 A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
 TITANIUM BARIUM PIGMENT 
 
 ISsuED, 1927. 
 
 1. ‘lhese specifications cover titanium barium pigment in the dry form, 
 also ground in oil to form a paste. 
 
 . MANUFACTURE 
 2. (a) Dry Pigment.—The pigment shall consist of titanium oxide precipi- 
 tated upon and coalesced with blane fixe (precipitated barium sulfate). 
 
702 Analysis of White Pigments 
 Le 
 
 (b) Paste.—The paste shall be made by thoroughly grinding the pigment 
 in pure raw or refined linseed oil. 
 
 PROPERTIES AND TESTS 
 3. (a) When specified, the color and color strength shall be equal to that 
 of a sample mutually agreed upon by the buyer and seller. 
 (b) Dry Pignent.—The pigment shall be thoroughly washed and shall 
 
 conform to tue following requirements: 
 MaxIMUM MINIMUM 
 
 Coarse particles (total residue retained on a 
 
 No. 325 screen*) per Cent........--+ee-ees 1.0 Pat 
 Titanium oxide (TiO,), per cent.......-+-+++--: ook 24.0 
 Total impurities, including moisture, per cent.. 1.0 oe 
 
 remainder remainder 
 
 Barium sulfate... 56. ve ces va sis 6 oo re ie oer 
 
 (c) Paste—The paste as received shall not be caked in the container and 
 
 shall break up readily in oil to form a smooth paint of brushing consistency. 
 
 It shall mix readily in all proportions, without curdling, with linseed oil, 
 
 turpentine or volatile mineral spirits, or any mixture of these substances. 
 The paste shall conform to the following requirements : 
 
 MAxIMUM MINIMUM 
 
 Pigment, per Cent. .....-. ee ee rece eee eer eecece ee 80.0 — 
 Linseed oil, per CeMt........---e eee eeeeeceees 20.0 Vite 
 Moisture and other volatile matter, per cent... 0.7 
 Coarse particles and “skins” (total residue re- 
 tained on a No. 325 scree,* based on pig- 
 ment), per Cent... 2... cere eereceeescess 1.5 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or fraction thereof. If the packages are of such size that 1000 amount to 
 more than a carload, one sample shall be taken at random from each carload. 
 
 A.S. T. M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
 WHITE PIGMENTS 
 
 I. METHOD FOR VERY SMALL AMOUNTS OF IRON. 
 
 Lead Pigments.—Treat sample with HNO, (1:1) in usual manner, dilute 
 with H,O, add H,SO, to precipitate bulk of lead (not necessary to evaporate 
 down) ; cool, filter, wash with 1 to 2 per cent of H,SO:, make filtrate just 
 alkaline with NH,OH, then just acid with dilute HNO,, determine iron colori- 
 metrically by the thiocyanate method, using same amounts of reagents in 
 preparing standards. If sample contains insoluble matter, filter out and 
 wash with hot water till Pb-free, and to filtrate add H,SO, and proceed as 
 given. The insoluble is ignited, treated with HF and H.SO, in usual manner, 
 brought into solution (filter out any BaSO:), and added to filtrate from 
 PbSO,. If necessary, solution may be made up to volume and aliquots taken. 
 Copper, if present, shall be removed by precipitating the Fe with NH,OH, 
 filtering, washing, redissolving Fe(OH), and proceeding as above. 
 
 Other Pigments.—Treat as above, omitting the addition of H.SO,. 
 
 Il GENERAL METHOD. 
 True specific gravity shall be determined in accordance with the Standard 
 
 * See footnote on page 697. 
 
 a 
 
 oy ee 
 
 ae Se 
 
 nS 
 = 
 :, 
 a 
 ~ 
 = 
 * 
 i 
 2 
 *. 
 + 
 7 
 = 
 * 
 
_ Analysis of White Pigments 703 
 
 Method of Test for Specific Gravity of Pigments (Serial Designation: D 153) 
 of the American Society for Testing Materials. 
 
 BASIC CARBONATE OF LEAD. 
 
 Total Lead (Gravimetric).—Dissolve 1 B20 Coote LENG we 1) ina 
 covered beaker, heating till all CO, is expelled; wash off cover, add 20 ce. of 
 H,SO« (1 : 1) and evaporate to fumes of SO,, cool, add about 150 cc. of water 
 and 150 ce. of ethyl alcohol; let stand in cold water 1 hour, filter on a 
 Gooch crucible, wash with 95-per-cent ethyl alcohol, Ory ab ios Co and 
 weigh PbSO,; calculate to PbO or to basic carbonate.* Instead of determin- 
 ing the lead as sulfate, the sample may be dissolved by boiling with acetic 
 acid; then dilute to about 200 ce. with water, make alkaline with NH,OH, 
 then acid with acetic acid, heat to boiling and add 10 to 15 ce. of a 10-per-cent 
 solution of potassium dichromate; heat till the yellow precipitate assumes 
 an orange color. Let settle and filter on a Gooch crucible, washing by de- 
 cantation with hot water till the washings are colorless finally transferring 
 all of the precipitate. Then wash with 95-per-cent ethyl alcohol and then 
 ether; dry at 110° C. and weigh PbCrOQ,. (Any insoluble matter should be 
 filtered out before precipitating the lead.) 
 
 Fotal Lead (Volumetric).—Dissolve 0.5 g. of sample in 10 ce. of concen- 
 trated hydrochloric acid, boil till solution is effected, cool, dilute to 40 ce., 
 neutralize with ammonium hydroxide. Add acetic acid until distinctly acid, 
 dilute to 200 cc. with hot water, boil and titrate with ammonium molybdate 
 as follows: 
 
 Dissolve 4.25 g. of ammonium molybdate in water and make up to one 
 liter. To standardize this solution, dissolve about 0.2 g. of pure lead foil in 
 nitric acid (pure PbO or PbSO, may also be used), evaporate nearly to dry- 
 ness, add 30 cc. of water, then 5 cc. H,SO, (sp. gr. 1.84), cool, and filter. 
 Drop filter with PbSO, into a flask, add 10 ec. of concentrated HCl, boil till 
 completely disintegrated, add 15 cc. of HCl, 25 cc. of water, and NH,OH till 
 alkaline. Acidify with acetic acid, dilute to 200 cc. with hot water and boil. 
 Titrate, using an outside indicator of one part of tannic acid in 300 parts 
 of water. ; 
 
 It should be noted that when calcium is present, it forms a more or less 
 insoluble molybdate, and results are apt to be high. With samples containing 
 less than 10 per cent of lead, the lead should be precipitated as PbSOs, filtered, 
 redissolved and titrated as in the process of standardizing. 
 
 Carbon Dioride.—Determine by evolution with dilute hydrochloric acid 
 absorbing in soda-lime or KOH solution. Calculate CO, to PbCO,, subtract 
 PbO equivalent from total PbO and calculate residual PbO to Pb(OH),. 
 
 Acetic Acid.j—Place 18 g. of the pigment in a 500-cc flask, add 40 cc. of 
 Sirupy phosphoric acid, 18 g. of zinc dust and 50 cc. of water. Connect to a 
 Straight Liebig condenser, apply heat and distill down to a small bulk. Then 
 pass steam into the flask until it becomes about half full of condensed water, 
 Shut off the steam and distill down to a small bulk—this operation being con- 
 ducted twice. To the total distillate which was collected in a larger flask 
 add 1 ce. of sirupy phosphoric acid, connect to a Liebig condenser, using a 
 Spray trap, and distill to a small volume—about 20 cc. Pass steam through 
 
 *This method of weighing lead sulfate is not accurate in the presence of 
 caleiuam compounds. 
 + Thompson’s Method, Journal, Soe. Chem. Ind., Vol. 24, p. 487 (1905). 
 
704 Analysis of White Pigments 
 
 , ; 
 
 till abeut 200 ec. of water condense in the distillation flask, shut off steam 
 and continue the distillation. These operations of direct and steam distilla- 
 tions are conducted until 10 cc. of the distillate require only one drop of 0.1 
 N alkali to give a change in the presence of phenolphthalein. Then titrate 
 the total distillate with 0.1 N sodium hydroxide and phenolphthalein and cal- 
 culate the total acidity as acetic acid. It will be found convenient to titrate 
 each 200-ce. portion of the distillate as collected. 
 
 Metallic Lead.*—Weigh 50 g. of the sample into a 400-cc. beaker, add a 
 little water and add slowly 60 ce. of 40-per-cent acetic acid and after efferves- 
 cence has ceased, boil on hot plate. Fill the beaker with water, let settle, 
 and decant the clear solution. To the residue add 100 ce. of a mixture of 
 360 cc. of strong NH:OH, 1080 cc. of water, 2160 ce. of 80-per-cent acetic acid 
 and boil until all solution is complete. Fill beaker with water, let settle and 
 decant the clear solution. Collect residue on a watch glass, floating off every- 
 thing but metallic lead. Dry and weigh. Result x 2= percentage of metallic 
 lead in-sample. 
 
 The following method of A. N. Finn (unpublished) gives total basicity 
 of a pure white lead: Place 2 g. of pigment in an evolution flask, add a little 
 CO,-free water, connect up to the separatory funnel and condenser (Knorr 
 type), add through the funnel, finally washing down, 100 cc. of N /4 nitric 
 acid, boil and absorb the CO, in soda-lime tube in usual manner (having 
 H,SO, and CaCl, drying tubes in train) and weigh. To the solution in the 
 evolution flask, add about 20 cc. of neutral sodium-suifate solution and titrate 
 with N /4 sodium-hydroxide solution (carbonate-free), using phenalphthalein. 
 CO, is calculated to PbCO,;. The amount of N /4 acid corresponding to the 
 CO, is calculated and deducted from the total amount of N /4 acid neutralized 
 by the sample and the difference calculated to combined H,O, from. which 
 Pb(OH), is computed. 
 
 Basic SuLFATE OF LEAD{ 
 
 Determination of Total Lead.—Dissolve 1 g. of the sample in 100 ce. of 
 a mixture consisting of 125 cc. of S80-per-cent acetic acid, 95 ec. of NHiOH 
 (sp. gr. 0.90) and 100 cc. of water. Add the solution while hot and dilute 
 with about 50 ce. of water, boil until sample is dissolved. Dilute to 200 ce. 
 and titrate with standard ammonium-molybdate solution as described under 
 basic carbonate of lead. The ammonium-molybdate solution contains about 
 8.67 g. per liter and is standardized against pure lead foil, pure PbO or pure 
 PbSOQ,. 
 
 Determination of Total Zine.—Boil 1 g. of the sample with 30 ce. of water, 
 4 g. of NH.Cl and 6 ec. of concentrated HCl (some PbSO, or PbCl, may not 
 dissolve). Dilute to 200 cc. with hot water, add 2 ce. of a saturated solution 
 of sodium thiosulfate and titrate with a standard solution of potassium ferro- 
 evanide in usual manner. Calculate the zine to ZnO,t as follows: 
 
 tIt would probably be more accurate to remove total lead as PbSO, and 
 titrate the zinc in the filtrate after adding NH,OH and HCl in usual manner. 
 99.10§—percentage of ZnO found = percentage of lead constituents ; 
 
 * Thompson's Method, Journal, Soe. Chem. Ind., Vol. 24, p. 487 (1905). 
 tJ. A. Schaffer’s Method, Journal of Industrial and Engineering Chemistry, 
 Vol. 6, p. 200 (1914), may be used. 
 {This figure (99.70) is the average total percentage of PbSO,, PbO and 
 ZnO, found in 270 total analyses of basic lead sulfate. 
 
 ae ee) f “ M 
 at ey ee ee ee 
 
Analysis of White Pigments 705 
 
 Then 
 ( At. wt.Pb. 
 
 Mol. wt. PbSO, — mol. wt. PbO 
 Mol. wt. PbO 
 
 Mol. wt. PbO 
 ——_— X % Pbhfound } — % Pb constituents 
 An wt, Pb. 
 
 $$ = % PSO, present 
 Mol. wt. PbO — Mol. wt. PbSO, 
 
 Mol. wt. PbSO, 
 
 Sulfur Dioxide.—Digest 2 g. of the sample with frequent stirring in 100 
 ce, of freshly boiled cold water and 5d cc. of concentrated HCl; let stand 10 
 to 15 minutes, add an excess of 0.01-normal iodine solution and titrate back 
 with 0.01-normal sodium-thiosulphate solution, using starch indicator. Report 
 as SO,. Run blank on reagents and make corrections. Or, the SO, may be 
 titrated directly with iodine. 
 
 oP b found ) — % Pb constituents 
 = % PbO present 
 
 Soluble Zinc Sulfate—Determine as under “Zinc-Lead and Leaded Zines.” 
 
 ZINC-LEAD AND LEADED-ZINCS—OZLO WHITE 
 
 Total Lead and Zinc.—Dissolve 1 g. of the sample by boiling with 250 ce. 
 of water and 20 cc. of concentrated HNO,;, add 5 cc. of concentrated H,SO,, 
 and evaporate to copious fumes of SO,; cool, add 250 cc. of water, let stand 
 cold 1 to 2 hours, filter on Gooch crucible, wash with 1-per-cent H,SO,, ignite, © 
 and weigh as PbSO,. Report as PbSO.. The PbSO, may be filtered on paper 
 and then dissolved and titrated with ammonium-molybdate solution as de- 
 scribed under basic carbonate of lead. Make filtrate from PbSOs« alkaline 
 with NH,OH, then acid with HCl, add 3 ce. of concentrated HCl, heat to 
 nearly boiling, and titrate the total zinc with potassium-ferrocyanide solution 
 using uranium-acetate solution as an outside indicator and calculate to ZnO. 
 (Iron, copper, or other interfering substances should first be removed as 
 described by Low.) 
 
 Sulfates other than Barium Sulfate—rTreat 0.5 g. of the sample with 5 cc. 
 of water, 3 g. of NH,Cl and 5 ce. of HCl saturated with bromine; digest 
 (covered) on steam bath about 15 minutes, add 25 ce. of water, neutralize 
 with dry Na,CO,, and add about 2 g. more, boil 10 to 15 minutes; let settle, 
 dilute with hot water, filter and wash with hot water; redissolve in HCl, 
 reprecipitate as above and wash thoroughly with hot water; acidify united 
 filtrates with HCl, adding a slight excess; boil and add slight excess of 10- 
 per-cent barium-chloride solution. Let stand on steam bath 1 hour, filter, 
 wash with hot water, ignite, and weigh BaSOs. Calculate to SO, (includes 
 SO, formed from SO,). Of, dissolve 0.5 g. of the sample in 25 ce. of water, 
 10 ce. of NH,OH (sp. gr. 0.90) and HCl in slight excess; dilute to about 150 
 ce. with water and add a piece of aluminum foil which should about cover 
 the bottom of the beaker—this held on bottom by means of a stirring rod. 
 Heat gently till all lead is precipitated, decant through a filter, pressing the 
 lead sponge with a flattened rod, and washing with hot water. Add to the 
 filtrate a little pure bromine water, boil until bromine is expelled, add 15 ee. 
 of 10-per-cent barium-chloride solution, lét stand on steam bath one hour, 
 
706 Analysis of White Pigments 
 
 filter, wash with hot water, ignite and weigh as BaSO, (any SrSO.« present 
 is not decomposed in this method) .* 
 
 Soluble Zinc Sulfate.—Heat nearly to boiling 2 g. of the sample with 150 
 ce. of water and 50 cc. of 95-per-cent alcohol for 30 minutes, filter, and wash 
 with a mixture of alcohol and water (1:3). Heat filtrate to boiling and expel 
 most of the alcohol; then determine SO, by usual method of precipitation 
 
 ~ 
 
 Norn—lIf sample contains Ca or Mg, the Pb and Zn should be separated | 
 by precipitation with H,S after dissolving in HCl, making alkaline with 
 NH,OH and acid with acetic acid. The PbS+ZnS is dissolved in dilute HNO, 
 and the Pb and Zn determined as above. ; 
 
 Sulfur Dioxide——Determine as under “Basic Sulfate of Lead” or “Zine 
 Oxide.” 
 
 ZINC OXIDE. 
 
 Total Zinc-—Dissolve 0.25 to 0.8 g. in 10 ce. of concentrated HCl and 20 
 ec. of H,O, make alkaline with NH,OH, then acid with HCl, add 3 cc. more 
 of concentrated HCl, dilute to about 250 cc. with H,O, heat nearly to boiling 
 and titrate with standard potassium-ferrocyanide solution as described by 
 Low.+ Report as ZnO (includes Cd). Iron, copper or other interferring 
 substances should be first removed as described by Low. 
 
 Total Soluble Sulfur.s—Moisten a 10-g. sample with water, add a few — 
 drops of bromine and then concentrated HCl, boil to expel bromine, filter — 
 from any insoluble and wash with hot water. Make alkaline with NH.O8, ~ 
 then just slightly acid with HCl, heat to boiling and add about 15 ce. of hot ~ 
 barium-chloride solution. Let stand several hours (over night), filter on a 
 weighed Gooch crucible, wash well with hot water, dry, ignite for five minutes, ~ 
 cool and weigh as BaSO,. Calculate to 8. og 
 
 Sulfur Dioxide.2—Mix 5 g. of sample with 50 cc. of warm (freshly boiled — 
 and then partly cooled) water to an emulsion and pour into a glass-stoppered — 
 flask containing 18 ec. of HCl and exactly 25 ce. of 0.1-normal iodine solution, 
 stopper and shake until all the oxide is dissolved. Titrate the excess of © 
 iodine as rapidly as possible with 0.1-normal sodium-thiosulfate solution, — 
 Caleulate to SO,. 
 
 Soluble Zine Sulfate-——Determine as under “Zinc-Lead and Leaded-Zines.” — 
 
 LITHOPONE 
 PONOLITH, JERSEY LILY WHITE, BECKTON WHITE, CHARLTON 
 WHITE, ORR’S WHITE. 
 
 Insoluble and Total Zine.—Take 1 g. of the sample in a 200-ec. beaker, — 
 add 10 ce. of concentrated HCl, mix, and add in small portions about 1 g. : 
 of KCIO,, then heat on the steam bath until about half of the liquid is evapo-— 
 rated. Dilute with H,O, add 5 ce. of dilute H,SO, (1:10); boil, let settle, © 
 
 filter, wash, ignite, cool, and weigh the insoluble which should be only BaSO4;_ 
 make a qualitative examination for alumina and silica. The insoluble 
 
 should be examined under the microscope for the presence of natural erystal- 
 
 * The solubility of BaSO, is increased by the presence of aluminum chloride. — 
 
 See J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 615. 
 + Low, “Technical Methods of Ore Analysis.” . 
 x Method of G. Rigg. 
 
Analysis of White Pigments 707 
 a em a le mee 
 
 lin barytes. Sample may also be examined direct. Make filtrate from in- 
 soluble alkaline with NH,OH, acid with HCl, add 3 ce. of concentrated HCl, 
 dilute to about 250 cc. with H,O, heat nearly to boiling and titrate with 
 K,Fe(CN), solution as under zine white. Calculate to Zn. 
 
 Zinc Oxride.—Treat a 4-g. sample of the lithopone for 4 hours with 200 ce. 
 of 1-per-cent acetic acid at room temperature, stirring occasionally. Filter 
 ’ by suction on a double filter paper and wash with cold water; add to the 
 elear filtrate 13 cc. of concentrated NH:OH, neutralize with HCl and then 
 add 3 ce. of concentrated HCl in excess. Heat to boiling and. titrate with 
 K,Fe(CN),, using uranium-acetate solution as an outside indicator. Calculate 
 to ZnO. Calculate this result to Zn, subtract from total “n, and calculate the 
 difference to ZnS. (Any ZnCO, or ZnSO, is included in the ZnO.) 
 
 Zine Sulfide.*—Place 0.5 g. of pigment in evolution flask with about 10 g. 
 of “feathered” or mossy zinc, add 50 ce. of water; insert the stopper carrying 
 a separatory funnel and an exit tube. Run in 50 ce. of concentrated HCl 
 from the funnel, having previously connected the exit tube to two absorption 
 flasks in series; first flask contains 100 ce. of alkaline lead-nitrate solution, 
 second flask, 50 cc. of same as a safety device. After all of the acid has run 
 into the evolution flask, heat slowly, finally boiling until the first appearance 
 of steam in the first absorption flask; disconnect, let the lead sulfide settle, 
 filter, wash with cold water, then with hot water till neutral to litmus paper 
 and washings give no test for lead. The PbS precipitate is dissolved in hot, 
 dilute HNOs, evaporated to fumes with H»SO, and finally weighed as PbSO4. 
 Calculate PbS or PbSO, to ZnS. 
 
 The alkaline lead solution is made as follows: Into 100 ee. of KOH solu-- 
 tion (56 g. in 140 cc. of H,O) pour a saturated solution of lead nitrate (250 
 g. in 500 cc. of H,O) until the precipitate ceases to redissolve, stirring con- 
 Stantly while mixing. About 3 volumes of the lead solution will be required 
 for one of the alkali. 
 
 Instead of absorbing the evolved H.S in alkaline lead-nitrate solution, a 
 Solution of 8 g. of cadmium chloride in 250 ec. of water and 150 ce. of NH,OH 
 (sp. gr. 0.90) may be used. The CdS precipitate may be filtered on a weighed 
 Gooch, washed with water containing a little NH,OH, dried at 100° C., and 
 weighed. Calculate to ZnS. It is better to filter the CdS on a Small filter 
 and wash as above, then place filter and precipitate in a beaker and dissolve 
 in HCl and KCIO, (keeping at room temperature at first), filter out any 
 paper pulp or insoluble matter; make filtrate alkaline with NH,OH, then just 
 acid with HCl, heat to boiling and precipitate with BaCl, in usual manner. 
 Filter, wash, ignite, and weigh BaSO, Calculate to ZnS. 
 
 For very rapid work the contents of the absorption flask, after all H.S 
 has been absorbed, may be washed into a vessel with cold water and diluted 
 to about one liter, acidified with concentrated HCl and titrated with standard 
 iodine solution, using starch indicator. (The precipitate should be completely 
 dissolved.) The iodine solution is prepared by dissolving about 12.7 g. of 
 pure resublimed iodine and 18 g. of KI in a little water and then diluting 
 to one liter. 
 
 — 
 
 * Kvolution Method of W. G. Scott, “White Paints and Painting Material,” 
 Dp. 257; see also Blair, “Chemical Analysis of Iron.” 
 
708 Analysis of White Pigments 
 
 CALCIUM PIGMENTS 
 WHITING, PARIS WHITH, SPANISH WHITE, AND CHALK. 
 
 Make a qualitative examination first; should contain only small amounts 
 of insoluble matter (siliceous), iron, aluminum, sulfur, water or magnesium, 
 and should be approximately 95 per cent CaCQ,. 
 
 Total Soluble Lime.*—Weigh out 0.75 g. of the pigment into a small cruci- 
 ble, ignite cautiously to dull redness to destroy organic matter, cool, transfer 
 to a 400-ce. beaker, add 20 cc. of H,O, cover, then add 15 ce. of concentrated 
 HCl and: 3 or 4 drops of concentrated HNO,, and boil till all the soluble matter 
 is dissolved and all the CO, expelled. Wash off and remove the cover, dilute 
 to about 150 ce. with freshly boiled H,O, heat to boiling and add dilute NH,OH 
 (sp. gr. 0.96) carefully until a slight permanent precipitate forms. Heat to 
 boiling and add 10 ce. of a 10-per-cent solution of oxalic acid; stir until the 
 oxides of iron and aluminum are entirely dissolved and only a slight precipi- 
 tate of calcium oxalate remains. Now add 200 ec. of boiling H,O and suffi- 
 cient saturated solution of ammonium oxalate (20 to 25 ce.) to precipitate 
 the lime. Boil and stir for a few moments, remove from the heat, let settle 
 and filter on an 11-cm. filter. Wash 10 times with 10-to-15-ce. portions of 
 hot water. Place beaker in which precipitation was made under the funnel, 
 
 pierce apex of filter with stirring rod and wash precipitate into beaker with — 
 
 hot water, pour warm dilute H,SO, (1:4) through paper and wash a few 
 times; add about 30 ce. of the dilute with H,SO,4 (1:4), dilute to about Za CC, 
 heat to 90° C. and titrate at once with standard KMnO, solution (solution 
 
 should not be below 60° C. when end-point is reached). The KMnOy, is best | 
 
 standardized against Bureau of Standards sodium oxalate.t Calculate to 
 CaO and CaCQ,. 
 
 Mixed Calcium and Magnesium Carbonate.z—Weigh 1 g. of the finely 
 powdered sample into a small porcelain dish, add 25 ce. of normal HCl, cover 
 with a watch glass, and when effervescence has ceased, heat to boiling. Cool 
 and titrate with normal NaOH solution, using methyl orange as indicator, 
 
 The calculation is as follows: 
 
 One gram CaO = 385.7 ce. of normal acid. CaO 1.784 == CaCG, “Sub : 
 
 tract number of cubic centimeters of NaOH required from 25, result gives 
 number of cubic centimeters of normal acid corresponding to the CaCO, ++ 
 MgCoO,. Multiply the weight of CaO in 1 g. of sample (as found in preceding 
 section on total soluble lime) by 35.7; product gives number of cubic centi- 
 meters of normal acid corresponding to the CaO present; subtract from total 
 number of cubic centimeters of acid required by CaCO, + MegCO, and multiply 
 
 result by 0.42, obtaining weight of MgCO, in 1 g. of sample. The MgCoO, — 
 
 determined by this process should not differ more than 0.25 per cent from 
 that obtained by more elaborate methods. It is to be noted that this method 
 is a measure of the total alkalinity, and if Ca or Mg are present in other 
 
 forms than carbonate, a complete analysis would be necessary to give per-— 
 
 centages of CaCO, and MgCO,. 
 
 Instead of the above, Newberry’s] method for the simultaneous determina- | 
 
 tion of calcium and magnesium carbonates may be used. 
 
 * Meade, “Portland Cement.” 
 + Circular No, 40, Bureau of Standards. 
 + J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 522. 
 
 §, Meade, “Portland Cement ;” Mellor, “A Treatise on Quantitative Inorganic 
 Analysis,” p. 522; Cement Engineering News, Vol. 15 Dp. 35 (1903). 
 
 2 
 7 
 
 ® 
 
Analysis of White Pigments 709 
 
 GYPSUM, TERRA ALBA, PLASTER OF PARIS 
 
 Combined Water and Moisture—Heat 1 g. of the sample in a covered 
 porcelain crucible on an asbestos plate for 15 minutes, then heat bottom 
 of crucible dull red for 10 minutes over a Bunsen burner, remove cover and 
 heat for 30 to 40 minutes at a slightly lower temperature. Cool and weigh 
 rapidly. Repeat to constant weight. 
 
 Combined water and moisture may also be determined by heating in an 
 air bath at 200° C. to constant weight. 
 
 Insoluble Matter.—Boil 2 to 3 g. of the sample with 20 cc. of concentrated 
 1iCl, a few drops of HNO;, and about 50 ce. of water; evaporate to dryness, 
 boil residue repeatedly with 10-per-cent HCl, decanting through a filter; 
 finally transfer to the filter, wash with hot water, ignite and weigh insoluble 
 matter; test for BaSO,. Make a qualitative examination of the filtrate from 
 the insoluble matter to determine if Al, Fe, or Mg are present in abnormal 
 amounts (should be mainly Ca and SO,). Test a separate portion of the 
 sample for CO.; if desired determine as under “Basic Carbonate of Lead.” 
 
 BARIUM PIGMENTS 
 BARYTES OR BARITE, ‘“‘BLANC FIXE” 
 
 Examine the sample microscopically to determine uniformity of grinding, 
 size and angularity of particles, crystallin or amorphous. The sample should 
 be at least 95 per cent BaSQ,. 
 
 Loss on Ignition.—Ignite 1 g. of the sample for 30 minutes. Loss may. 
 be due to organic matter, moisture, combined water and CO, (and SO, from 
 CaSO, if present). If loss is appreciable, test for CO,. 
 
 Soluble and Insoluble Matter.—Boil 1 g. with HCl (1:3), filter, wash with 
 hot water, ignite, and weigh insoluble matter. This may be treated with 
 H.SO, and HF in usual manner for SiO, In the absence of <Al,O, (from 
 silicates) residue is considered as BaSO,. Make qualitative tests of filtrate 
 from the insoluble for Al, Fe, Ca, Mg, SO,;. Test a separate portion of 
 sample qualitatively for CO.. 
 
 SILICA PIGMENTS 
 SILICA OR SILEX 
 Silica or silex should be practically pure SiO, <A qualitative examina- 
 tion will suffice in most cases with a determination of the loss on treating 
 1 g. of sample with H,SO,4 and HF in usual manner. 
 
 CHINA CLAY AND ASBESTINE 
 
 A qualitative analysis of China clay to determine if essentially hydrous 
 aluminum silicate is generally all of the chemical tests necessary. Color, 
 fineness, etc., are more important than analysis. 
 
 Asbestine is tested qualitatively to prove that material is as represented. 
 Color, fineness, etc., are important. Asbestine should be examined under the 
 microscope to note whether it is fibrous or taleose and whether silica or 
 China clay are admixed. Samples of known origin should be used here as a 
 guide for comparison. 
 
710 Analysis of White Pigments 
 
 A. S.T. M- STANDARD METHODS OF ROUTINE ANALYSIS OF 
 
 TITANIUM PIGMENTS 
 GENERAL METHODS 
 SPECIFIC GRAVITY 
 
 1. True specific gravity shall be determined in accordance with the Stand- 
 ard Method of Test for Specific Gravity of Pigments (Serial Designation: 
 D 153) of the American Society for Testing Materials.” 
 
 COLOR 
 
 2. To 5 g. of the sample add 1.5 cc. of linseed oil, rub on a stone slab or 
 glass plate with a flat-bottomed glass or stone pestle or muller to a uniform 
 
 paiey 
 
 smooth paste. Treat in a similar manner 5 g. of the standard titanium ~ 
 
 pigment. Spread the two pastes side by side on a clear, colorless glass 
 plate and compare the colors. If the sample is as white as, or whiter than, 
 the “standard,” it passes this test . 
 
 CoLoR STRENGTH 
 3. Weigh accurately 0.01 g. of lampblack, place on a large glass plate 
 or stone slab, add 0.2 cc. of linseed oil and rub up with a flat-bottomed glass 
 pestle or muller, then add exactly 10 g. of the sample and 2.5 ce. of linseed 
 
 oil, and grind wth a circular motion of the pestle or muller 50 times ; gather | 
 
 up with a sharp-edged spatula and grind out twice more in a like manner, : 
 
 giving the pestle or muller a uniform pressure. Treat another 0.01 g. of 
 
 lampblack in the same manner except that 10 g. of standard pigment is — 
 used instead of the 10 g. of the sample. Spread the two pastes side by side 2 
 on a glass microscope slide and compare the colors. If the sample is as light = 
 
 or lighter in color than the “standard” it passes this test. 
 
 COARSE PARTICLES 
 
 4. Determine coarse particles in accordance with the Standard Methods j 
 of Test for Coarse Particles in Paint Pigments (Serial Designation: D 185) — 
 
 of the American Society for Testing Materials. 
 
 METHODS OF ANALYSIS 
 QUALITATIVE ANALYSIS 
 
 5. Place about 0.5 g. of the sample in a 250-cc. Pyrex glass beaker ; add | 
 
 20 cc. of concentrated H.SO, and 7 to 8 g. of (NH,).SO, Mix well and © 
 boil for a few minutes. The sample should go completely into solution; a — 
 
 residue denotes the presence of silica or siliceous matter. Cool the solution, — 
 dilute with 100 ce. of water, heat to boiling, let settle, filter, wash with hot — 
 5-per-cent H.SO, until free from titanium, and test the residue for lead, ete. — 
 Test the filtrate for calcium, zine, iron, chromium, ete., by the regular methods eS 
 of qualitative analysis. For the iron determination add to a portion of the © 
 filtrate 5 g. of tartaric acid, render slightly ammoniacal, pass in H,S in excess, — 
 and digest at side of steam bath for a while. No precipitate indicates the $ 
 
 absence of iron, ‘nickel, cobalt, lead, copper, ete. A black precipitate readily — 
 
 soluble in dilute HCl denotes iron. For titanium, test a small portion of the . 
 
 original filtrate with hydrogen peroxide (a clear yellow-orange color should — 
 result) and another portion with metallic tin or zine (a pale blue to violet 
 
Analysis of White Pigments 711 
 
 coloration should result). Negative tests should be shown for sulfide sulfur, 
 carbonates, and appreciable water-soluble matter. 
 
 MOISTURE 
 6. Place 1 g. of the sample in a wide-mouthed short weighing tube provided 
 with a glass stopper. Heat with stopper removed for two hours at a tempera- 
 ture between 105 and 110° C. Insert stopper, cool, and weigh. The loss in 
 weight is reported as moisture. 
 
 MATTER SOLUBLE IN WATER 
 7. Transfer 2.5 g. of the pigment to a graduated 250-cc. flask, add 100 ce. 
 of ‘water, boil for 5 minutes, cool, fill to mark with water, mix, and allow to 
 settle. Pour the supernatant liquid through a dry filter paper and discard the 
 first 20 cc. Then evaporate 100 cc. of the clear filtrate to dryness in a 
 weighed dish, heat for one hour at 105 to 110° C., cool and weigh. 
 
 TITANIUM OXIDE 
 
 8. Transfer 0.5 g. of the dried sample to a 250-cc. Pyrex beaker, add 20 ce. 
 of concentrated H,SO, and 7 to 8 g. of ammonium sulfate. Mix well and 
 heat on hot plate until fumes of sulfuric acid are evolved, and then continue 
 the heating over a strong flame until solution is complete (usually requires 
 not over five minutes of boiling) or it is apparent that the residue is composed 
 of silica or siliceous matter. Caution should be observed in visually examin- 
 ing this hot solution. Cool the solution, dilute with 100 cc. of water, stir, heat 
 carefully to boiling while stirring, let settle, filter through paper and transfer 
 the precipitate completely to the paper. Wash the insoluble residue with cold © 
 5-per-cent (by volume) H.SO, until titanium is removed. 
 
 Dilute the filtrate to 200 cc. and add about 10 cc. of NH,OH (sp. gr. 0.90) 
 to lower the acidity to approximately 5-per-cent H.SO, (by volume). 
 
 Wash out a Jones reductor* with dilute 5 per cent by volume H,SO; and 
 water, leaving sufficient water in the reductor to fill to the upper level of the 
 zinc. (These washings should require not more than one or two drops of 
 0.1 N KMnO, solution to obtain a pink color.) Empty the receiver, and put 
 in it 25 cc. (measured in a graduate) of ferric sulfate solution (see Re- 
 agents). Reduce the prepared titanium solution as follows :+ 
 
 (1) Run 50 cc. of the 5-per-cent H.SO, solution through the reductor at 
 a speed of about 100 cc. per minute. 
 
 (2) Follow this with the titanium solution. 
 
 (3) Wash out with 100 cc. of 5 per cent H.SO,. 
 
 (4) Finally run through about 100 cc. of water. Care should be taken 
 that the reductor is always filled with solution or water to the upper level 
 of the zinc. Gradually release the suction, wash thoroughly the glass tube 
 that was immersed in the ferric sulfate solution, remove the receiver, and 
 titrate immediately with 0.1 N KMnO, solution. One ce. of 0.1 N KMn0O, 
 equals 0.00481 g. Ti or 0.008 g. TiO, Run a blank determination, using the 
 
 * Directions for preparing a Jones reductor may be found in Blair, “The 
 Chemical Analysis of Iron,” Eighth Edition, pp. 88-89, or Treadwell-Hall, 
 “Analytical Chemistry,” Vol. 2, Fifth Edition. 
 
 7 Lundell and Knowles, “The Determination of Titanium by Reduction 
 with Zine and Titration with Permanganate,” Journal, Am. Chemical Soc, 
 Vol. 45, p. 2620 (1923). 
 
Viz Analysis of White Pigments 
 
 aS 
 
 same reagents, washing the reductor as in the above determination. Subtract 
 this permanganate reading from the original reading and calculate the final 
 reading to titanium dioxide (TiO.). This will include iron, chromium, arsenic, 
 and any other substance which is reduced by zine and acid. See Calculations 
 below for reporting TiO,. 
 
 BARIUM SULFATE 
 9. Ignite, cool, and weigh the precipitate of BaSO, obtained in separating — 
 the titanium in Section 8. . 
 
 Note.—If sample is impure it may be necessary to purify this precipitate, 
 using appropriate methods. 
 
 IRON OXIDE. 
 
 10. Prepare a standard ferric solution containing 0.00001 g. of Fe per 
 cubic centimeter (see Reagents). Weigh a 1-g. portion of the sample and 
 treat as in Section 8. Transfer without filtering to a graduated 200-cc. flask, 
 cool, fill to the mark with water, mix, let settle, and determine iron colori- 
 metrically as follows: Filter through a dry filter paper, discarding the first 
 20 ce.; transfer 50 ce. of the clear filtrate to a clean 100-ce. Nessler tube or 
 other comparator. Add a drop or two of 0.1 N KMn0O, solution to oxidize 
 any ferrous iron. The faint pink color should persist for at least 5 minutes. 
 Add 10 ec. of KCNS or (NH,)CNS solution (see Reagents), dilute with water © 
 to 100 ce., and mix thoroughly. Compare the color immediately with a series 
 of standards, prepared side by side with the sample, in similar tubes. Pre- 
 pare the standards from the standard ferric solution so as to have a range 
 of from 0.000005 g. Fe to 0.00004 g. Fe (0.5 to 4.0 ce.). Transfer the desired 
 volumes of the standard ferric solution to 100-cc, Nessler tubes containing 50 — 
 ec. each of an acid solution (made up by dissolving 8 g. of (NH,).SO, in water, 
 adding 20 ce. of concentrated H,SO,, cooling, diluting with water to 200 cc., 
 and mixing), add a drop of 0.1 N KMn0O, solution (or sufficient to yield a = 
 pink color that will persist for 5 minutes), and then 10 cc. of the thiocyanate i 
 solution. Finally dilute all standards with water to 100 cc. and mix each 
 thoroughly. 
 
 Nore.—For a single sample it is more convenient to run the standard Fe 
 solution from a burette into a Nessler tube, containing 50 ce. of acid solution 
 (made by dissolving 8 g. of (NH,).SO, in water, adding 20 cc. of concentrated 
 H,SO,, cooling and diluting with water to 200 ce., and mixing), a drop of 0.1 NV 
 KMn0O, solution, 10 cc. of the thiocyanate solution, and then dilute with dis- 
 tilled water until the depth of the color produced after diluting 100 cc. and — 
 mixing, exactly matches that of the sample. From the burette réading ealcu- 
 late the amount of Fe. When using standards, the color comparisons must be — 
 made immediately. 
 
 CALCULATIONS i 
 
 11. Caleulate the total iron found to Fe.O, and report as such. Calculate — 
 the TiO, equivalent by multiplying the Fe.O, result by the factor 1.003 and — 
 subtract this figure from the total TiO, as determined in Section 8 and report 
 the remainder as TiO.. . 
 
 Report all results on the dry or moisture-free basis. 
 SOLUTION REQUIRED : 
 12. Decinormal Potassium Permanganate Solution.—Dissolve 3.2 g. of pure — 
 
 KMn0Q, in 1 liter of distilled water, let stand 8 to 14 days, siphon off the clear — 
 
Analysis of White Pigments 713 
 
 solution (or filter through asbestos), and standardize as follows: In a 400-ce. 
 beaker dissolve 0.25 to 0.30 g. (accurately weighed) of U. S. Bureau of Stand- 
 ards’ sodium oxalate in 250 ce. of hot water (80 to 90°C.) and add 15 ce. 
 of dilute H,SO, (1:1). Titrate at once with the KMn0O, solution, stirring 
 the liquid vigorously and continuously. The KMnO, must not be added more 
 rapidly than 10 to 15 ce. per minute, and the last 0.5 to 1 cc. must be added 
 dropwise with particular care to allow each drop to be fully decolorized before 
 the next is introduced. The solution should not be below 60° C. by the time 
 the end point is reached. (More rapid cooling may be prevented by allowing 
 the beaker to stand on a small asbestos-covered hot plate during the titration. 
 The use of a small thermometer as a stirring rod is most convenient.) ‘I'he 
 weight of sodium oxalate used multiplied by 0.833 gives its iron equivalent, 
 or multiplied by 1.195 gives its titanium dioxide equivalent. The KMnQ, 
 solution should be kept in a glass-stoppered bottle painted black to keep out 
 light. 
 
 Ferric Sulfate Sclution for Titanium.—A solution containing 2 per cent of 
 iron as ferric sulfate is desired and may be prepared as follows: Dissolve 
 20 g. of pure iron or plain carbon steel in a slight excess of HCl, oxidize with 
 HNO,, add about 80 ec. of H.SO, and heat until fumes of the latter are evolved. 
 Cool, dilute with water to 1000 ec., digest on a steam bath until sulfates are 
 dissolved, and filter if necessdry. Add 0.1 N KMn0O, solution until a faint 
 pink color persists for 5 minutes (to oxidize any ferrous iron that may be 
 present). 
 
 Ferric ammonium sulfate may be used also.* 
 
 Standard Ferric Sulfate Solution for Colorimetric Determination of Iron.— 
 Determine the strength of the ferric solution for the TiO, determination in 
 terms of Fe and dilute a portion of this solution until one is obtained of the 
 strength 1 ec. equals 0.00001 g. Fe. 
 
 Potassium Thiocyanate Indicator.—Prepare a 2-per-cent solution of the 
 pure salt in distilled water. 
 
 Carbon Dioxide Test on White Pigments.—A simple and 
 efficacious method of determining carbonic acid in white pig- 
 ments, which has been used in this laboratory, will be found 
 below. 
 
 The method can be used in such cases where the substances 
 to be analyzed evolve gases other than carbon dioxide; that is, 
 hydrogen sulphide, sulphur dioxide, or organic matter. The 
 apparatus used is shown in Fig. 226. A weighed sample of 
 the substance is introduced into the Erlenmeyer flask (A). 
 Into flask (B) is placed a 10 per cent solution of barium chlor- 
 ide, more than sufficient to hold the carbon dioxide evolved, 
 and 20 ce. of concentrated ammonium hydroxide free from 
 carbon dioxide. If sulphides are present, it is sometimes ad- 
 visable to pass the liberated gas first through a few cc. of 
 
 * Gooch, “Methods in Chemical Analysis,” First Edition, p. 436. 
 
714 Analysis of White Pigments 
 
 strong potassium permanganate. The flask (B) is warmed 
 until completely filled with ammonia fumes. Flask (C) is a 
 safety bottle containing the same solution as flask (B). Only 
 in rare cases will any trace of the carbon dioxide be noticed — 
 in the safety flask. After flask (B) is completely filled with — 
 ammonia vapor, make all connections and allow the hydro- ~ 
 chloric acid to drop slowly from the separatory funnel into — 
 the decomposition flask (A). When effervescence has ceased, 
 heat the contents of the flask until filled with steam. The de- — 
 
 FIGURE 226 
 
 Carbon Dioxide Apparatus 
 
 livery tubes and sides of the precipitating flask are then 
 washed with boiling water, the flask is filled to the neck, stop- — 
 pered, and the precipitated barium carbonate allowed to settle. 
 Wash thoroughly by decantation, each time stoppering the 
 flask to prevent any error from the carbon dioxide present in 
 the air, and determine either gravimetrically, by conversion 
 into barium sulphate, or volumetrically, by dissolving in stand- 
 
Analysis of White Pigments jh) 
 
 ard hydrochloric acid and titrating the excess of acid used with 
 standard potassium hydroxide. Calculate the barium found 
 to carbonate and the amount of carbon dioxide from the found 
 earbonate. The entire operation may be hastened by conduct- 
 ing a brisk current of air free from carbon dioxide through 
 the entire apparatus. 
 
 Jamieson Determination of Zinc.*—The zinc is obtained in 
 an HCl or HeSO, solution of not more than 5 per cent HCl. 
 The solution is made up to 100 ee. and an aliquot containing 
 not more than 0.10 gm. ZnO taken. If the volume taken ex- 
 ceeds 35-ce., it should be concentrated to that amount. Add 
 without stirring 25 ec. of the precipitating reagent, which 
 consists of 19.5 grams potassium thiocyanate and 13.5 grams 
 mereuric chloride in 500 ce. distilled water. Filter onto a 
 tarred gooch and wash with a solution containing 10 ee. of the 
 precipitating reagent in 500 cc. of water. Dry for one hour 
 at 102-107° C. and weigh. The precipitate is ZnHg (SCN),. 
 HO but becomes on heating at the above temperature ZnHg 
 
 (SCN),. 
 
 Factors 
 ZnHg(SCN), to Zn, Multiply by 0.1312 
 ZnHg(SCN), to ZnO, Multiply by 0.1632 
 ZnHe(SCN), to ZnS, Multiply by 0.1954 
 
 The following interfere: cadmium, cobalt, copper, bismuth, 
 manganese, and mercurous compounds. Lead, if present, may 
 be first removed by adding sulphuric acid to the solution be- 
 fore making it up to volume. If appreciable amounts of ferric 
 compounds are present, they may be reduced with sulphur 
 dioxide, otherwise some ferric thiocyanate may be carried 
 down with the zine precipitate. Nickel in small amounts does 
 not interfere. 7 
 
 Volumetric Method.*—If desired instead of filtering on a 
 gooch as referred to in the first paragraph, the precipitate 
 may be collected on a small paper in a Hirsch funnel and, after 
 washing, transferred with the paper to an iodine titration 
 bottle. A thoroughly cooled mixture of 35 ce. of HCl, 10 ee. 
 against a standard solution of potassium iodate containing 
 
 =G. $8. Jamieson, Ie Sache a bea th atey, (1918), Volumetric Iodate Methods, 
 Chem. Cat. Co., p. 86 
 
716 Analysis of White Pigments 
 
 39.2882 erams per liter, 1 cc. of which is equivalent to 0.0020 — 
 erams zine. 
 
 During the first part of the titration, the potassium iodate — 
 solution is added rapidly while rotating the bottle in order to ~ 
 keep the contents mixed. When the iodine which is liberated ~ 
 during the first stage of the reaction has disappeared from the ~ 
 solution, the stopper is inserted and the contents of the bottle — 
 are thoroughly mixed by shaking for about half a minute. — 
 From this point the titration is continued slowly, shaking the ~ 
 closed bottle thoroughly after each addition of potassium 
 iodate until the iodine color has disappeared from the chloro- — 
 form indicator which marks the end point. If more than 50 ~ 
 ec. of the potassium iodate solution is required for a titration, 
 10 to 15 ee. more of hydrochloric acid should be added before — 
 continuing the titration, in order to prevent the hydrolysis ‘ 
 of the iodine monochloride. 
 
 Inside Indicator in Zinc Titration.—In place of uranyl ni- 
 trate which is used as an outside indicator in zinc titrations, 
 diphenyl benzidine may be used as an inside indicator. ‘This 
 method which was described by Cone and Cady, J. Am. Chem. ~ 
 Soe. 49, 356-40(1927), conducts the titration in a sulphuric acid 
 solution with the ferrocyanide solution containing 0.3 g. of © 
 potassium ferricyanide per liter. The change in color is © 
 from purple to pale green. 2 
 
 Mixed Calcium Pigments.—In the above A. S. T. M. Meth- — 
 ods, the analysis of mixtures of calcium carbonate and mag- — 
 nesium carbonate are referred to. Among other mixtures — 
 
 which might be present are calcium carbonate and calcium — 
 
 sulfate. In the analysis of paints containing such mixtures, — 
 carbon dioxide or sulphur trioxide should be determined, and ~ 
 the calcium oxide equivalent calculated. The other component 
 may then be calculated from the residual calcium oxide. ; 
 Calcium Compounds in Titanium Pigments—Calcium ti- — 
 tanium pigments sometimes contain calcium phosphate or — 
 other calcium compounds. Heat carefully 1 gram of the pig- — 
 ment with dilute HCl. Filter and wash. Remove the lead © 
 
 with H.S. Boil the filtrate from the lead determination to — 
 
 remove the H2S, neutralize, add 1 ce. of HNOs, then ammonium ~ 
 acetate solution and acetic acid. Boil, and filter off the basic — 
 ferric acetate. Any zinc may be removed from the filtrate 
 with H2S and determined as on page 715. Boil the sR to ; 
 
Analysis of White Pigments 717 
 
 remove H2S and determine the calcium as oxalate as described 
 on page 708. 
 
 CaO X 1.84 = Cas(PO,)2 
 
 Phosphates.—Boil 1 gram of the pigment with HNO; (1:1). 
 Filter and determine the phosphoric acid in the filtrate by the 
 phospho-molybdic method. 
 
CHAPTER XL 
 
 _ ANALYSIS OF LEAD OXIDES 
 
 There are given below the A. 8. T. M. Standard specifica- — 
 tions for red lead, and methods of analysis. Following these © 
 
 specifications are presented some special methods for deter- 
 
 mining red lead, as used in factories where these pigments are 
 
 produced. There are also included special methods for de- 
 
 termining such impurities as copper, iron, and free silica in ~ 
 
 red lead. 
 A. 8S. IT. M. STANDARD SPECIFICATIONS FOR 
 RED LEAD | 
 
 1. These specifications cover red lead to be used as a pigment, purchased i 
 in the form of dry pigment or ground in oil to form a paste. $ 
 I. MANUFACTURE . 
 2. (a) Dry Pigment.—The pigment shall be made by roasting litharge or 
 lead, or compounds of lead which yield litharge by heating. 3 
 (v) Paste.—The paste shall be made by thoroughly grinding the specified Fa 
 pigment in pure raw or refined linseed oil. % 
 Nore.—Avoid storing red lead paste in places of high temperature, as heat : 
 accelerates the tendency of this material to cake or harden. z 
 Purchasers are cautioned not to buy red lead in paste form unless it is to 
 be used within three months after shipment by the contractor. @ 
 II. PROPERTIES AND TESTS x 
 3. (a) Dry pigment shall consist entirely of oxides of lead, free from all : 
 adulterants and shall conform to the following requirements: a 
 85-Per-Cent 95-PeR-CENT 
 GRADE GRADE ; 
 True red lead, Pb,O,, minimum, per cent...... 85.0 95.0 2 
 Total impurities, including moisture, soluble 7 
 matter, water, and matter insoluble in a ¥ 
 mixture of nitric acid and hydrogen per- 3 
 oxide, maximum, per Cent.........++se+-=- 1.0 1.0 3 
 a 
 85-PeR-CeENT 95-Per-CENT 
 GRADE GRADE $e 
 The remainder shall be lead monoxide (PbO if 
 Coarse particles retained on a Standard No, a 
 325 screen, maximum, per cent...........-- 2:0 1.0 é 
 When mixed with raw linseed oil, turpentine and liquid drier, in the ~ 
 proportions : # 
 Dry red lead... ...e0c. scenes tess 0 sa bee 0 5 Mion re 20° Ib. bs 
 Raw linseed ofl... son. g seq cols sot © oipieis «isin m kely ean 5 pt. = 
 Turpentine ....06sse sew cce wens nes © ose olemtns a ne 2 gills x 
 Liquid. drier... ccs cece ce eens e ohie wn ae gee 2° e* S: 
 
 an ‘ : is 
 
 ay 
 
 Se 
 
Analysis of Lead Oxides 719 
 enna lr ee ad 
 
 the resulting paint, when brushed on a smooth vertical iron surface, shall 
 dry hard and elastic without running, streaking or sagging. 
 
 (b) .Paste.—The paste as shipped by the contractor, and for three months 
 thereafter, shall not be caked in the container and shall readily break up in 
 oil to form a smooth paint of brushing consistency. The paste shall have the 
 following composition: 
 
 MAXIMUM MINIMUM 
 uMEMP ICT CONG I 4 50) Poco. Soe kee Cele edna 94.0 92.0 
 Semele Der Gent. 5 oo... sc ce veces. 8.0 6.0 
 
 Moisture and other volatile matter, per cent... 0.5 
 
 Coarse particles and skins (total residue re- 
 tained on a Standard No. 325 sereen, based 
 Mere rcne WeVerreent. sia. ace oko se has ee 1.5 
 
 When mixed with raw linseed oil, turpentine and liquid drier in the fol- 
 lowing proportions: 
 
 Ty SEES GA ie et ek a gee en 20 Ib. 
 NM et Teer ei ne, oh. ee 43 pt. 
 (TONNES nce TADEN ci gs a 2 gills 
 
 Liquid drier 2 N 
 the resulting paint, when brushed on a smooth vertical iron surface, shall 
 dry hard and elastic without running, streaking or sagging. 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each ecarload. 
 
 A.S. T. M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
 DRY RED LEAD 
 1. The approximate formula of Red Lead is Pb,O, (probably PbO..2PbO). 
 
 SPECIFIC GRAVITY 
 2. True specific gravity shall be determined in accordance with the Stand- 
 ard Method of Test for Specific Gravity of Pigments (Serial Designation: 
 D 153) of the American Society of Testing Materials. 
 
 MOISTURE 
 3. Dry 2 g. of the sample for 2 hours at 105° C. The loss in weight is 
 considered as moisture. . 
 
 ORGANIC COLOR 
 4. Boil 2 g. of the Sample with 25. cc. of 95-per-cent ethyl alcohol, jet 
 Settle, decant off the Supernatant liquid; boil residue with water, decant as 
 before and boil residue with very dilute NH,OH. If either the aleohol, water 
 or NH,OH is colored, organic coloring matter is indicated. 
 
 TOTAL LEAD AND INSOLUBLE MATTER 
 5. Treat 1 g. of the sample with 15 ce. of HNO, (1:1) and sufficient H.O, 
 to dissolve all PbO, on warming. If any insoluble matter is present, add 25 
 ec. of water, boil, filter and wash with hot water. The insoluble matter con- 
 tains free SiO, and should be examined for BaSO, and silicates, if appreci- 
 able. To the original solution or filtrate from insoluble, add 20 ce. of con- 
 centrated H,SO, and evaporate to SO, fumes; cool, add 150 cc. of water and 
 
720 Analysis of Lead Oxides 
 
 150 ec. of 95-per-cent ethyl alcohol, let stand cold 2 nours, filter on a Gooch 
 crucible, wash with 95-per-cent alcohol, dry at 105 to 110° C. and weigh as 
 PbSO,. Calculate to PbO. Red lead is rarely adulterated, but should sample 
 contain soluble barium compounds, the PbSO, obtained above will contain 
 BaSO,. In this case, digest above precipitate with acid ammonium-acetate 
 solution, filter off BaSO,, wash, ignite and weigh BaSO,. Calculate to BaO 
 
 or BaCO,. In filtrate, determine the lead as PbSO, or PbCrO, If sample ;, 
 
 contains significant amounts of calcium or magnesium, the HNO,-H.O, solu- 
 tion is boiled till all lead is converted into nitrate and then the lead is 
 determined as PbCrQ,. 
 
 If calcium and magnesium are to be determined, proceed as follows: 
 Precipitate the lead as sulfide from a slightly acid (HCl) solution, dissolve 
 the PbS in hot dilute HNO, and determine the lead as sulfate. Boil the fil- 
 trates from the PbS to expel H,S, add a little bromine water to oxidize iron 
 (if present), boil to expel bromine, and then add NH,OH in slight excess. 
 Filter off any precipitate of Fe(OH),+Al1(OH);; wash with hot water. (If 
 appreciable, redissolve in hot dilute HCl and reprecipitate with NH,OH, 
 ignite and weigh Fe,0,+Al,0;.) Manganese, if present, can be precipitated 
 by adding bromine and NH,OH and warming; filter, wash with hot water, 
 ignite and weigh as Mn,O, Unite all of the filtrates, make slightly acia 
 with acetic acid, heat to boiling and pass H,S into the hot solution till satu- 
 rated (20 to 30 minutes) ; add 5 g. of NH,Cl and let stand 5 hours; filter off 
 
 any ZnS, wash with H,S water, dissolve the ZnS in hot dilute HCI and de- — 
 
 termine the zine by titration with K,Fe(CN),. Or, boil off the H.S, filter out 
 any separated sulfur and determine the zinc as Zn,P,0; Calcium may be 
 determined in the filtrate from the ZnS by expelling H,S and then adding 
 
 NH,OH and ammonium oxalate in the usual manner. Titrate with KMnQ,. — 
 
 In the filtrate from calcium determine magnesium in the usual manner by 
 precipitating with sodium-phosphate solution, finally weighing as Mg,P.0,. 
 
 LEAD PEROXIDE (PbO,) AND TRUE RED LEAD (Pb304) 
 
 (Method of Diehl* modified by TopftZnot applicable when substances are 3 
 present, other than oxides of lead, that liberate iodine under conditions — 
 
 given). 
 
 6. Weigh 1 g. of finely ground sample into a 200-ee. Erlenmeyer flask, — 
 
 add a few drops of distilled water and rub the mixture to a smooth paste — 
 
 with a glass rod flattened on end. Mix in a small beaker 30 g. of c. p. | 
 
 “Tested Purity” crystallized sodium acetate, 2.4 g. of c. p. KI, 10 cc. of © 
 
 water and 10 cc. of 50-per-cent acetic acid; stir until all is liquid, warming 
 
 gently; if mecessary add 2 to 3 cc. of water, cool to room temperature and — 
 
 pour into the flask containing the red lead. Rub with the glass rod until 
 
 nearly all the red lead has been dissolved; add 380 ce. of water containing 5 — 
 or 6 g. of sodium acetate, and titrate at once with decinormal sodium thio- — 
 
 sulfate, adding the latter rather slowly and keeping the liquid constantly in 
 
 motion by whirling the flask. When the solution has become light yellow, — 
 rub any undissolved particles up with the rod until free iodine no longer 
 forms, wash off rod, add the sodium-thiosulfate solution until pale yellow, — 
 add starch solution and titrate until colorless, add decinormal iodine solution” 
 
 * Dingl. polyt. Jour., Vol. 246, p. 196. 
 + Zeitschrift fiir analytische Chemic, Vol. 26, p. 296. 
 
Analysis of Lead Oxides 721 
 
 until blue color is just restored and subtract the amount used from the 
 volume of sodium thiosulfate that had been added. 
 
 Calculation.—The iodine value of the sodium-thiosulfate solution multi- 
 plied by 0.942 — PbO,; the iodine value multiplied by 2.7 = Pb,O,; the PbO, 
 value multiplied by 2.866 = Pb,O,. 
 
 The sodium-thiosulfate solution and the starch solution shall be prepared 
 as follows: 
 
 Sodium-Thiosulfate Solution (decinormal).—Dissolve 24.83 oF. Oly G1 De 
 sodium thiosulfate, freshly pulverized and dried between filter paper, and 
 dilute with water to 1 liter at the temperature at which the titrations are to 
 be made. The solution is best made with well-boiled water free from CO,, 
 or let stand 8 to 14 days before standardizing. Standardize with pure, re- 
 sublimed iodine, as described in Treadwell-Hall, “Analytical Chemistry,” 
 Vol. II, p. 602 (1910), and also against pure potassium iodate; the two 
 methods of standardization should agree within 0.1 per cent on iodine value. 
 
 Starch Solution.—Stir up 2 to 8 g. of potato starch with 100 ce. of 1-per- 
 cent Salicylic-acid solution, and boil the mixture till starch is practically dis- 
 solved, thne dilute to 1 liter,* or as per Lord. ; 
 
 DETERMINATION OF ZINC 
 7. If in appreciable amount, evaporate off the alcohol from the filtrate 
 from total lead, make alkaline with NH,OH, then acid with HCl, add 8 ee. 
 more of concentrated HCl, dilute to about 250 cc. with water, heat nearly to 
 boiling and titrate with standard K,Fe(CN), solution as described by Low. 
 Report as ZnO (includes cadmium). Iron, copper or other interfering sub- 
 Stances should first be removed as described by Low. 
 
 WATER-SOLUBLE 
 
 8. Digest 10 g. of sample with 200 cc. of hot water on steam bath for 1 
 hour; filter on an 11-cm. S. & S. blue-ribbon paper and wash with hot water 
 till no residue is left on evaporating a few drops of the washings. Evaporate 
 filtrate to dryness on steam bath in a weighed dish, dry 30 minutes at 105° C., 
 cool and weigh. Take up with water and if alkaline, titrate with tenth 
 hormal acid and methyl orange; calculate to Na.CQ,. 
 
 Another lot of water-soluble matter is tested for nitrates, nitrites, carbon- 
 ates, sulfates, sodium and lead. 
 
 TOTAL SILICA 
 9. Digest 5 g. of the sample in a covered casserole with 5 cc. of HCl and 
 15 ce. of HNO, (1:1). Evaporate to dryness to dehydrate. Cool, treat with 
 hot water and HNO,, boil, filter, wash with hot acid ammonium-acetate solu- 
 tion, then dilute HCl and finally hot water. Ignite and weigh as SiO,. The 
 residue may be treated with H.SO, and HF in cases of doubt as to purity. 
 
 *Lead Peroxide—If sample contains an appreciable amount of nitrate 
 (nitrate has no effect on method), leach out water-soluble matter as below, 
 dry residue and determine PbO, as above, calculating to basis of original 
 sample. 
 
 ¥ “Notes on Metallurgical Analysis,” p. 103 (1903). 
 
 t Low, “Technical Methods of Ore Analysis.” 
 
722 Analysis ot Lead Oxides 
 
 CARBON DIOXIDE 
 
 10. Determine carbon dioxide by the evolution method, using dilute HCl — 
 
 and stannous chloride. 
 
 DETERMINATION OF SOLUBLE SULFATE 
 11. Sulfates other than Barium Sulfate.—Treat 0.5 g. of the sample with 
 5 ee. of water, 3 g. of NH,Cl and 5 ce. of HCl saturated with bromine; digest 
 
 (covered) on steam bath about 15 minutes, add 25 ce. of water, neutralize — 
 with dry Na.CO,, and add about 2 g. more, boil 10 to 15 minutes; let settle, — 
 
 dilute with hot water, filter and wash with hot water; redissolve in HCl, 
 
 reprecipitate as above and wash thoroughly with hot water; acidify united — 
 filtrates with HCl, adding a slight excess; boil and add slight excess of 10- 
 per-cent BaCl, solution. Let stand on steam bath 1 hour, filter, wash with — 
 
 hot water, ignite, and weigh BaSO,. Calculate to SO, (includes SO, formed 
 from SO.,). ) 
 
 Or, dissolve 0.5 g¢. of the sample in 25 ec. of water, 10 cc, of NH,OH (sp. 
 gr. 0.90) and HCl in slight excess; dilute to about 150 ce. with water and 
 add a piece of aluminum foil which should about cover the bottom of the 
 beaker—this held on bottom by means of a stirring rod. Heat gently till 
 
 all lead is precipitated, decant through a filter, pressing the lead sponge with ~ 
 
 a flattened rod, and washing with hot water. Add to the filtrate a little 
 pure bromine water, boil until bromine is expelled, add 15 cc. of 10-per-cent 
 
 BaCl, solution, let stand on steam bath one hour, filter, wash with hot water, — 
 
 ignite and weigh as BaSO, (any SrSO, present is not decomposed in this 
 method. ) * 
 IRON OXIDE 
 
 12. Determine iron oxide by Schaeffer’s} modification of Thompson’s | 
 colorimetric method; or, in a large beaker, treat 20 g. of the sample with 20 — 
 cee. of water, 20 cc. of HNO, (sp. gr. 1.4) and 8 ec. of formaldehyde solution. — 
 
 Warm till all PbO, is dissolved, dilute with water, warm, filter off insoluble 
 and wash with hot water. Ignite filter and insoluble, evaporate with H,SO, 
 
 and HF. To filtrate from insoluble add 14 ce. of H,SO, (1:1), filter off © 
 PbSO,, and wash. Dissolve residue from HF and H,SO, in H,SO, and add to — 
 
 filtrate from PbSO,; dilute to 500 ce. and determine iron colorimetrically in an 
 
 aliquot, using same amounts of HNO,, H.SO, and formaldehyde in comparison ~ 
 
 solution.t Calculate to Fe,Q,. 
 
 Figg Method for Red Lead.f{—One gram of the red lead is 
 treated in a glass mortar with 40 cc. of a saturated solution 
 of sodium acetate in 5 per cent acetic acid, and a known excess — 
 
 (40 of 50 ee. of 0.1 N solution) of sodium thiosulfate is— 
 
 added. The reaction proceeds slowly and rubbing with pestle 
 is needed to complete it. The presence of any undecomposed 
 
 * The solubility of BaSO, is increased by the presence of aluminum chloride, 
 See J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 615. 
 
 + Journal of Industrial and Engineering Chemistry, Vol. 4, p. 659 (1912). 
 
 + Lunge-Berl, “Chemisch-technische Untersuchungs-Methoden,” Bd, 2, S. 95, 
 
 6th Ed. 
 q E. F. Figg, J. Oil & Col. Chem. Assoc. 8, 101 (1925). 
 
 ee ee ee ee ee ee 
 
Analysis of Lead Oxides 723 
 
 red lead is easily observed in the clear solution, and rubbing 
 is continued as long as any remains. The addition of a few 
 ec. of 5 per cent potassium iodide solution facilitates the re- 
 duction of the more resistant particles of red lead, and does 
 not affect the titration. A few drops of starch solution are 
 then added, and the excess of thiosulphate is titrated with 
 0.1 N iodine solution. The large excess of sodium acetate 
 prevents the precipitation of lead iodide, and the end-point of 
 the titration is, in consequence, sharp. 
 
 Schaeffer Method for Red Lead.—Treat 1 gram in a beaker 
 with 15 ce. of nitric acid, sp. gr. 1.2 (110 ce. nitric acid sp. gr. 
 1.42 to 100 ce. of water). Stir the sample until all trace of red 
 color has disappeared. Add from a calibrated pipette or bur- 
 ette exactly 10 ce. of dilute hydrogen dioxide (1 part of 3 per 
 cent hydrogen dioxide to 3.5 parts of water). Add about 50 
 ce. of hot water and stir until all the lead dioxide has passed 
 into solution. In the case of some coarsely ground oxides the 
 contents of the beaker may have to be gently heated to effect 
 complete solution. After the oxide has completely passed into 
 solution, dilute with hot water to about 250 ce. volume and ti- 
 trate directly with a standard potassium permanganate solu- 
 tion, having an iron value of 0.005. Titrate to the faint pink 
 permanganate color. A blank titration on the hydrogen diox- 
 ide solution must now be made. 
 
 Into a beaker pour 15 ce. of nitric acid of above strength and 
 add exactly the same amount of hydrogen dioxide (10 cc.). 
 Dilute to 250 ce. with hot water and titrate with standard 
 potassium permanganate solution to a faint pink color. 
 
 The difference between the number of ce. of potassium per- 
 manganate required for the blank titration and the number 
 required for the red lead titration is the amount required for 
 the hydrogen dioxide which was reacted on by the red lead. 
 The difference between the two amounts of potassium per- 
 manganate required multiplied by 3.058 grams gives the per- 
 centage of red lead present. The difference multiplied by 
 1,067 gives the percentage of PbOz present. 
 
 In certain instances it is found that red lead in flake form 
 is soluble only with the greatest difficulty by the above pro- 
 cedure. In cases where this difficulty is encountered the fol- 
 lowing method will be found to give excellent results, espe- 
 clally for flake red lead. 
 
724 ? Analysis of Lead Oxides 
 
 Digest 1 gram of the sample in a beaker with 15 ce. of nitric 
 acid made up of a strength as given in the previous method. 
 Boil the solution for a short time, add 10 ee. of a standard 
 oxalic acid solution, the strength of which has been previously 
 determined. Add 2 cc. of sulphuric acid (1:1). Boil the solu- — 
 tion and titrate with a standard solution of potassium per- ~ 
 manganate having an iron value of 0.005. <A blank titration — 
 on the same amount of oxalic acid must be made. The differ- 
 ence between the amount of potassium permanganate required 
 for the blank titration and that required for the red lead titra- 
 tion multiplied by the factor 3.058 or 1.067 will give the con- 
 tent of red lead or lead dioxide according to the proportions 
 in the previous analysis. 
 
 Copper Content of Red Lead.—Treat 30 grams of the sam- 
 ple with 40 cc. (1:1) nitric acid, using great care that the 
 violence of the reaction does not cause the sample to froth — 
 over the beaker. Slowly add 30 to 40 ce. of 3 per cent hydro- 
 gen peroxide,* stirring constantly. Boil until solution is — 
 effected. Add 32 ce. (1:1) sulphuric acid, stirring constantly — 
 while adding. Let the precipitate settle, and decant filtrate 
 through a coarse filter paper. Wash four times by decanta- — 
 tion, using small portions of warm, distilled water. Transfer — 
 the precipitate to the paper, wash again and allow to drain. 
 Make the filtrate neutral with ammonium hydroxide and add — 
 4 cc. excess. Boil for a short time and filter. Wash the pre- — 
 cipitate well with warm water, and reserve for the determina- 
 tion of the iron. Render the filtrate acid with special ec. p.— 
 hydrochloric acid, adding not more than two drops excess. 
 Add six drops of (1:10) potassium ferrocyanide solution, filter — 
 through close filter papers using two to each funnel. Catch — 
 the filtrate and inspect for copper ferrocyanide. Let the pre- 
 cipitate drain well without washing. Dissolve the copper fer-— 
 rocyanide off of the paper with alternate washings of small — 
 portions of ammonium hydroxide and hot water. Wash well © 
 and keep the bulk to 30 or 40 ce. Render slightly acid with — 
 hydrochloric acid, adding not over two drops excess. Transfer — 
 to a 100-cc. Nessler tube, and dilute to mark with distilled ~ 
 water. The copper is then determined colorimetrically ac- ¢ 
 
 *Sodium sulfite c.p. may be used in place of hydrogen peroxide for ofrectiii 
 the solution of lead peroxide, adding it dry in small portions and-boiling until — 
 no brown lead peroxide is present. 
 
 : 
 : 
 
Analysis of Lead Oxides 725 
 
 cording to a modification of the method of Carnelly. In an- 
 other Nessler tube, place 10 cc. of 5 per cent ammonium ni- 
 trate solution, two drops concentrated nitric acid and 90 ce. 
 distilled water, add from a burette graduated to tenths of 1 ce. 
 standard copper sulphate solution until the color matches the 
 sample under examination. 
 
 Standard Copper Sulphate Solution.—< Dissolve 0.393 gram 
 of pure CuSO..5H20, in one liter of distilled water. 1 cc. = 
 0.0001 gram of copper,’’ or 0.00033 per cent when using a 30- 
 gram sample. 
 
 Copper may also be determined gravimetrically as follows: 
 Twenty grams of the pigment contained in a 200-ce. flask are 
 dissolved in nitric acid (50 ce, concentrated nitric acid to 100 
 cc. water). Boil to complete solution. Add 40 ec. of dilute 
 sulphuric acid (1:1), boil gently for one hour and allow 
 to cool. Filter off the lead sulphate and wash the precipitate 
 thoroughly. Nearly neutralize all the free acid present with 
 ammonium hydroxide, render slightly acid with hydrochloric 
 acid, warm the solution and pass in hydrogen sulphide until no — 
 further precipitation of sulphide occurs. Filter off the pre- 
 cipitate without washing, using some of the filtrate to transfer 
 the last traces of sulphide to the filter paper. Dissolve the 
 precipitate in a little nitric acid and wash the filter paper 
 thoroughly with hot water. Add 3 ce. of concentrated sul- 
 phuric acid, evaporate until the white fumes of sulphurie acid 
 are evolved and allow the solution to cool. Add a little water 
 and allow to stand for some hours. Filter off the lead sul- 
 phate, washing with hot water containing a little sulphuric 
 acid. 
 
 Heat the filtrate to boiling and precipitate the copper as sul- 
 phide with hydrogen sulphide in an ammoniacal solution. Fil- 
 ter off the copper sulphide through an ashless filter paper, 
 wash, ignite and weigh in a covered porcelain crucible, from 
 which the heat and cover are occasionally removed for a few 
 seconds. 
 
 The precipitate will consist of a mixture of CuO and Cu.S. 
 Since the percentage of copper is the same in both of these, the 
 copper may be determined by multiplying the amount found by 
 the factor 0.799. 
 
726 Analysis of Lead Oxides 
 
 Iron Content of Red Lead.—For the iron determination, use 
 the precipitate of iron hydroxide removed from the copper — 
 solution, proceeding as follows: Dissolve the precipitate con- — 
 tained on the paper with (1:1) hydrochloric acid, collecting the ~ 
 filtrate in a 300-ce. volumetric flask. Wash the paper free from E 
 acid with hot, distilled water, dilute to mark, and mix thor-— 
 oughly. Place 10 ce. in a 100-cc. Nessler tube, add three drops ; 
 nitric acid, 10 ec. (1:15) ammonium sulphocyanide solution, — 
 dilute to mark and compare with a standard iron solution, = 
 
 ai 
 
 Plath SRI 2 
 
 The color is compared with a blank made in the following 
 manner: <A solution of ferric ammonium sulphate of known — 
 strength is required. This is made by dissolving 0.7022 gram — 
 of ferrous ammonium sulphate in water. Acidify with sul- ~ 
 phuric acid, heat to boiling and add a solution of potassium — 
 permanganate until all the iron is converted to the ferric con- ‘ 
 dition. Only the very slightest pink tinge may be present — 
 after the addition of the potassium permanganate, as this ; | 
 tinge will fade away, while the presence of a pink color tends ~ 
 to vitiate the results. Allow the solution to cool and dilute to 
 one liter. One ee. of this solution equals 0.0001 gram of iron. 
 
 Prepare the blank by pouring into a 100-ee. Nessler cylinder, 
 10 ce. ammonium sulphocyanide solution, and three drops of — 
 concentrated nitric acid. Dilute to 100 ec. and titrate to the © 
 exact color developed in the sample under examination, by the — 
 addition of the standard ferric ammonium sulphate solution. — 
 One cc. of this solution equals 0.01 per cent iron as the 10 ce. © 
 removed from the flask contained 1 gram sample. It will be — 
 found that the color can be accurately compared to within 
 0.001 per cent of iron content. 
 
 Te ca SET LE ae 
 
 pict 
 
 Free Silica Content of Red Lead.—The free silica may be de- — 
 termined by dissolving the litharge in dilute nitric acid. Heat 
 to boiling, filter, wash, ignite and weigh as silica. 4 
 
 omer: 
 
 Free Metallic Lead—Two grams of the sample are treated _ 
 in a beaker with hot water and just sufficient acetic acid ig 
 slowly added, to dissolve the lead oxide. Stir the solution well © 3 
 and note whether any lead silicate remains undissolved. 4 
 Should such remain, continue stirring until solution has been 4 
 
 = 
 
 . 
 os 
 Re 
 
Analysis of Lead Oxides 727 
 
 effected. The solution should never have greater than a 5-per- 
 eent acetic acid strength. 
 
 Filter the solution and wash the residual metal three or four 
 times by decantation with hot water, having all the wash 
 water pass through the filter paper, which is finally thoroughly 
 washed with hot water. Transfer any metal on the filter 
 paper to the beaker containing the residual lead nitric acid 
 and heat to solution. Dissolve in nitric acid and determine 
 in the usual manner. 
 
CHAPTER XLI 
 
 ANALYSIS OF REDS OTHER THAN IRON OXIDES. 
 
 Cadmium Red. The cadmium red pigments* are a recent — 
 development and consist of cadmium sulfide (CdS) contain- 
 ing various amounts of cadmium selenide (CdSe). Barium ~ 
 Aeitiie may also be present in the form of cadmopone. The — 
 colors range from orange to maroon, depending upon the ~ 
 proportions of the ingredients. As the fumes from selenium ~ 
 are poisonous, the analysis should be done in a hood. 
 
 Insoluble Matter.—One gram of the pigment is heated ina ~ 
 beaker with concentrated nitric acid and Br. until the selenium — 
 color is discharged. ‘The solution is then diluted with water ~ 
 and after digesting 1 hour, the BaSOs. is filtered off and 
 weighed. The sulfur which was present as sulfide may be ~ 
 determined in the filtrate from the insoluble BaSO: by boiling — 
 with concentrated HCl to reduce the selenic acid to selenious — 
 acid, diluting to 200 ec., heating to boiling and precipitating 
 as BaSO: with 10% BaCl, solution. 
 
 Selenium.t—One gram of the pigment is heated with con- — 
 centrated nitric acid until free from color and the insoluble ~ 
 matter is filtered off. 10 grams of c. p. NaCl is added and 
 the solution concentrated to about 25 ec. HCl is then added 
 to replace the HNOs. The solution is then made up to 100 ee. 
 so that it contains at least 50% of concentrated HCl (1.19) 
 and heated to 100° C. SOs is then passed through the solu- 
 tion, or NaHSOs is added until the Se is entirely precipitated. 
 The digestion is continued until the selenium is converted to 
 the black modification, filtered on a Gooch crucible, washed 
 first with 50% HCl, then with dilute HCl and then with water. 
 It is dried at 105° C. and weighed as metallic selenium. 
 
 Cadmium.i—The filtrate from the determination is concen- 
 trated to about 25 ec., nearly neutralized with NHs, diluted — 
 to 100 ce. and then saturated with H:S. The precipitate is 
 filtered, washed and then dissolved in dilute HCl. The solu- 
 tion is evaporated to dryness in a weighed Pyrex beaker, 5 
 
 at ae — t . Fi egy - Ss a 
 ae Maa eg Mee rate. aan NEA ll gh ini e Teodh eS 
 
 *H. Dudley Ward, J. Oil & Colour Chem. Soc. X 4, (1927.) 
 *Scott. Standard Methods of Chemical Analysis. 
 tSeott. Standard Methods of Chemical Analysis. 
 
 ON So ee oe Seen maT ee : as 
 eel Nee ie te a a arr 
 
Analysis of Reds Other Than Iron 729 
 
 ec. of concentrated H:SO. added and the excess expelled at 
 low red heat. 
 
 CdSO: X 0.539 = Cd 
 
 Cadmium Lithopone (yellow or orange). This pigment 
 is a chemically precipitated pigment containing approximately 
 68 per cent barium sulphate, the balance consisting princi- 
 pally of yellow cadmium sulphide with some zinc sulphide. 
 It is not affected by hydrogen sulphide. For moisture, water 
 soluble, total sulphides, and oxides, see methods for lithopone. 
 
 Method for Cadmium and Zine Sulphides.—Take 1 gram of 
 the sample in a 200 ee, beaker, add 15 ce. of concentrated inl OlR 
 mix, and add in small portions about 1 g. KC1Os, then heat on 
 the steam bath until about half of the liquid is evaporated and 
 the yellow color of the CdS has disappeared. (If necessary 
 a few ce. of concentrated HNO; may be added at this point to 
 effect the solution of the CdS.) Then add 15 ce. of 1-1 sul- 
 phuric acid and evaporate to fumes of SOs. Cool, dilute with 
 100 ce. of water, filter off, and weigh the insoluble barium sul- 
 phate and examine it for alumina and silica (not likely to be | 
 present). 
 
 To the filtrate from the insoluble, add water until volume is 
 200 ce. Cool and pass a rapid stream of H2S gas through the 
 solution for 15 minutes. Add dilute NH.OH, drop by drop 
 until yellow cadmium sulphide begins to precipitate. Heat 
 the solution to about 90° C. and again pass HS for five min- 
 utes. Boil the solution for a few minutes, let settle,, and filter 
 through close-grained paper, washing the precipitated CdS 
 with cold 10% sulphuric acid and with hot water. Save fil- 
 trate for zine. 
 
 Dissolve the sulphide on the filter in 1-2 HC] in a clean 
 beaker, add 15 ce. (1-1) sulphuric acid, take to fumes, and 
 repeat precipitation of CdS. Filter through weighed Gooch 
 crucible, wash with 10% sulphuric acid and hot water, dry at 
 110° ©. for one hour, and weigh as CdS. 
 
 Combine the two filtrates from the CdS precipitation, cool 
 thoroughly, make slightly alkaline with NH,OH, and pass a 
 rapid stream of H2S gas for ten minutes. Heat to boiling, let 
 settle, filter on fine-grained paper, wash well, and ignite care- 
 fully in crucible to ZnO. Factor ZnO to ZnS — 1.1975. 
 
730 Analysis of Reds Other Than Iron 
 
 Cuprous Oxide Red in Antifouling Paints. The red cuprous ~ 
 oxide used in antifouling paints can be analyzed in accordance ~ 
 with the following method: Weigh accurately about 0.25 g. of 
 the dry sample into a 250-ce. ground glass stoppered Hrlen- 
 meyer flask. Add 10-15 ec. of acid ferric chloride solution — 
 (200 g. FeCls. 6 H2O in 500 ce. of 1:1 HCl), and a few glass © 
 beads, stopper, and rotate until the oxide is completely dis- 
 solved (usually within 2 or 3 minutes on high-grade finely 
 ground samples). Warm on the steam bath, if necessary, — 
 but it is not advisable and generally unnecessary. Add 9 cc. © 
 of syrupy phosphoric acid, 200 ce. of cool distilled water, and — 
 titrate the ferrous iron with decinormal KMnO, to the first — 
 permanent (30 seconds) color change. A blank (usually about : 
 3 drops) should be run on the reagents. 
 
 1 ee. O. 1 N KMnO, = 0.00636 g. Cu. 
 = 0.00716 Cuz0 
 
 Analysis of Vermilions. The following portion of Walker’s® — 
 method will suffice for the examination of Mercury Vermilion. ~ 
 Should the analyst desire to determine the sulphide of mereury — 
 present or make a more complete examination reference — 
 may be made to the original method. . 
 
 “True vermilion, or, as it is generally called, English ver- — 
 milion, is sulphide of mercury. On account of its cost it is — 
 rarely used in paints, and is liable to gross adulteration. It — 
 should show no bleeding on boiling with alcohol and water and ~ 
 no free sulphur by extraction with carbon disulphide. A — 
 small quantity mixed with five or six times its weight of dry 
 sodium carbonate and heated in a tube should show globules — 
 of mercury on the cooler portion of the tube. The best test — 
 for purity is the ash, which should be not more than 0.5%. 
 Make the determination in a porcelain dish or crucible, using ~ 
 2 grams of the sample. Ash in a muffle or in a hood with a— 
 very good draft, as the mercury fumes are very poisonous. — 
 It is seldom necessary to make a determination of the mer-— 
 cury. Genuine mercury vermilion is at the present time little | 
 used in paints.’’ | 
 
 *P, H. Walker, Miscellaneous Publications, No. 15, U. S. Bureau of — 
 Standards, p. 32. 7 
 
731 
 
 f Reds Other Than Iron 
 
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Ps Analysis of Reds Other Than Iron 
 
 Identification of Color Lakes.—There is given on page 731 a . 
 
 chart showing the results obtained in this laboratory upon a — 
 
 number of organic colors used in the paint industry. The tests 
 
 were made with five different reagents. The method of test — 
 
 consisted in pouring the reagent on a watch glass and then ~ 
 
 incorporating a small amount (approximately 0.1 gram) of 
 the color lake in the reagent by means of a stirring rod. The 
 
 precipitates noted in many instances might be composed of © 
 
 an inert base on which the dyestuff was formed. 
 
 Orgamc Reds.—Organic lakes are used for most of the bril- © 
 
 liant red, scarlet and vermilion shades. These organic color- 
 
 ing matters are sometimes precipitated on red lead, orange ~ 
 
 mineral or zinc oxide; but as a usual thing the base is barytes, 
 
 whiting or china clay. Paranitraniline red, a compound of ~ 
 
 diazotized paranitraniline and beta-napthol, is largely em- 
 ployed; but a number of colors may be used. ‘The examina- 
 tion of these reds follows the method as communicated to 
 the writer by EK. F. Hickson. 
 
 Qualitative Tests for Reds.—In qualitatively testing ver- 
 
 milions (para red, toluidine red, and lithol red) the following — 
 suggestions may be useful: (1) Para Red. The intense pur- — 
 ple color in a mixture of alcohol (ethyl or denatured) and — 
 
 sodium hydroxide solution distinguishes para red from the ~ 
 other two. (2) Toluidine and Inthol Reds. (a) Chloroform — 
 
 Test.—A small amount (0.1 g. or less) of C. P. toluidine red, — 
 
 when stirred into 100 ce. of warm chloroform, gives a practi- — 
 eally clear, orange red solution within one hour. Lithol red — 
 
 eo 
 
 under the same conditions remains practically undissolved, 
 even overnight, giving a nearly colorless filtrate. (b) Sodwm 
 Carbonate.—C. P. toluidine red is exceptionally resistant to 
 strong alkalies and acids. A boiling solution of fairly strong 
 sodium carbonate will have practically no effect on the bright 
 orange red color of the toluidine, whereas the lithol red (bar- 
 ium lake), will be converted to the sodium salt. Make both 
 liquids slightly acid with dilute sulphuric acid and without 
 filtering, place a piece of clean, freshly washed wool in each, 
 and allow to remain for 10 minutes. Take each piece of wool 
 and wash thoroughly with mild soap and water, taking care 
 to wash off any absorbed pigment particles. The lithol dyes 
 the wool a fast, uniform pink (coral) color that will not wash 
 out. the toluidine does not dye the wool. 
 
Analysis of Reds Other Than Iron 733 
 
 Percentage of Pigment in Paste or Paint.—In separating 
 the pigment from the vehicle, petroleum ether has been found 
 to dissolve out only a slight amount of organic color. An- 
 other suggested solvent for separating the pigment from ve- 
 hicles is a mixture of two-thirds to three-quarters petroleum 
 ether and one-third to one-quarter ethyl ether. Benzol or 
 the mixed solvents do not work well with some samples of 
 vermilion paint. (The reader is also referred to Federal 
 Specification Board Specification No. 66 for Red Enamel, in 
 the back of this book.) Weigh accurately about 15 g. of the 
 paste or paint into a weighed centrifuge tube. Add 20 to 30 
 ce. of petroleum ether, mix thoroughly with a glass rod, wash 
 the rod with more of the petroleum ether, and add sufficient 
 of the reagent to make a total of 60 ce. in the tube. Place the 
 tube in the container of a centrifuge, surround with water, 
 and counterbalance the container of the opposite arm with a 
 similar tube or a tube with water. Whirl at a moderate speed 
 until well settled. Decant the clear supernatant liquid. Re- 
 peat the extraction twice using petroleum ether. After draw- 
 ing off the last extract, set the tube on top of a warm oven for 
 10 minutes, then in an oven at 110 to 115° C. for two hours. 
 Cool, weigh, and calculate the percentage of pigment. Grind 
 the pigment to a fine powder, pass through a No. 80 screen to 
 remove any skins, and keep in a stoppered bottle. 
 
 Analysis of Pigment.—Test the pigment first qualitatively. 
 Place a small portion of the pigment in a 50 ec. beaker and 
 add about 25 cc. of alcoholic KOH or NaOH. Para-red will 
 turn a dark reddish purple. Pour off the colored solution, 
 and repeat until all the color is in solution and a white base 
 remains. Add a little HNOs to some of the base to show the 
 presence of carbonate. A white base, giving no effervescence 
 or test for COs, is probably composed of silicates or silicate 
 and barium sulphate. Occasionally the base contains orange 
 mineral; the addition of HNOs will turn this pigment brown 
 and bleach out on adding a few drops of dilute NaNOz solu- 
 tion. 
 
 Percentage of Color—Weigh accurately about 0.5 g. por- 
 tion of the pigment into a 250 ce. beaker, add about 100 ce. of 
 warm chloroform, and stir with a glass rod, breaking up any 
 lumps. Decant the colored solution through a weighed Gooch 
 crucible, and leave the residue in the beaker. Add a 50 ce. 
 
734 Analysis of Reds Other Than Iron 
 
 SS SSS SSS SSS SSNS 
 
 portion of chloroform to the residue and stir well with a glass © 
 
 rod, breaking up any lumps. Decant the colored solution 
 through the Gooch crucible and repeat the washing of the 
 residue in the beaker with 50 ce. more of chloroform. Finally 
 transfer the residue onto the Gooch crucible, and continue the 
 washing with chloroform from a wash bottle until the base is 
 white or the washings colorless. Dry the Gooch crucible at 
 105-110° C. to constant weight and report the loss as ‘‘pure 
 color.’’ 
 
 Nore.—In case the examination of the pigment shows calcium carbonate 
 to be absent and the base to be barium sulphate and silicates, a direct loss on 
 ignition using 1 g. of the sample will generally check the above within 0.5 per 
 cent. 
 
 In case the base contains calcium carbonate, hydrated clays, 
 
 ? 
 alumina, etc., an ignition loss cannot be calculated to organie 
 
 color, since ids results are too high, due to loss of combined 
 water in the clay. 
 
 The above method for percentage of color will give in most 
 cases a base free from organic color with about 250-300 ee. of 
 chloroform. 
 
 Some samples have been washed with the following mixture ~ 
 for the percentage of color and satisfactory results were ob- — 
 
 tained: 
 
 10 vol. ethyl ether, 6 vol. benzol, 4 vol. methyl alcohol, 1 vol. 
 acetone, and made lesen with NaOH. 
 
 This is followed with alcoholic NaOH, alcohol and aha 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
 COMMERCIAL PARA RED 
 
 1. These specifications cover a red paint pigment commonly known as com- 
 
 mercial para red. The pigment may be purchased in the dry form or ground ~ 
 
 in oil or in japan to form a paste. 
 
 MANUFACTURE. 
 2. (a) Dry Pigment.—The pigment shall be para nitraniline red toner, pre- 
 cipitated on a white base consisting of barium sulfate with or without siliceous 
 materials. 
 
 (b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
 
 the specified pigment in pure raw or refined linseed oil. 
 
 (c) Paste in Japan—tThe paste in japan shall be made by thoroughly - 
 
 grinding the specified pigment in high-grade grinding japan. 
 
 os alent 
 
 ara GF i am 
 
 SPEC af ctl ent NER tain eet Be 
 
 er es gee aE ah li 
 fia o eatin oe Mei Nas era 
 
 aes 
 
 CNS mer 
 jie ae Tit 
 
 a 
 
 =. 
 
 Opin geen praia: 
 
Analysis of Reds Other Than Iron 735 
 es Lc ite aac ea 
 
 PROPERTIES AND TESTS 
 3. (@) The mass color and character of the tint formed by mixture with 
 a white pigment shall be the same as, and the strength shall be not less than 
 that of a sample mutually agreed upon by the buyer and seller. 
 (6) Dry Pigment.—The dry pigment shall conform to the following require- 
 ments: 
 MAXIMUM MINIMUM 
 
 Pure organic coloring matter (para red), per cent .. 10.0 
 Bereemur SIL Pale, Per Cent .< 6s. os cc cece cece oes -. 60.0 
 amemerMPTMAUOTIAL Cr. sens cccs «cs ce ea cc cee « remainder remainder 
 Coarse particles retained on a No. 325, screen, 
 
 OUST on GIB Ano BS ie ea 1.5. 
 
 (¢) Paste in Oil—The paste as received shall not be caked in the con- 
 tainer and shall break up readily in oil to form a smooth paint of brushing 
 consistency. It shall mix readily in all proportions, without curdling, with 
 linseed oil, turpentine or volatile mineral spirits, or any mixture of these 
 substances. The paste shall conform to the following requirements: 
 
 MAXIMUM MINIMUM 
 
 ele EM TG OE MESO cc, ss ices occ vs cose cca ce cae be eee 78.0 
 RENN OUNCE. ie cic kd ic v0'c o'ece tcc s Gee 22.0 Se 
 ~ Moisture and other volatile matter, per cent.... 0.7 
 Coarse particles and skins (total residue re- 
 tained on a No. 325 screen, based on pig- 
 PISPEN I EIT ORT ieee wae vices 0 wale vw asd wecaee 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the 
 container and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency that will dry within one hour to a hard flat coat that can 
 be varnished within five hours of the time of application, without streaking 
 or bleeding. The paste shall conform to the following requirements: 
 
 MAXIMUM MINIMUM 
 
 Ser RB POCOTYE 62S oe. oc oie s,s c's vos vee nes een aah 78.0 
 Pomc losjapaiy, per Cents. ke... cece ees cos toe 22.0 sr 
 Coarse particles and skins (total residue re- 
 
 tained on a No. 325 screen, based on pig- 
 
 BCPC re aiid 6c cic vie dey'e 04 bs 00 Bw bles 2.0 
 Non-volatile matter in the vehicle, per cent of 
 
 SEG Peps in cig a a oie 005i do ae Rae we obo hBe ees 40.0 
 
 4. One sample shall be taken at random from each lot of 1000 packages or 
 fraction thereof. If the packages are of such size that 1000 amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
CHAPTER XLII 
 
 ANALYSIS OF YELLOW, ORANGE, BLUE AND GREEN PIGMENTS ~ 
 
 The material on this subject presented in the previous edi- 
 tions of this work has been utilized in the drafting of A. 8. 
 T. M. specifications which are given below. These methods 
 
 are followed by special methods of general interest. | 
 
 A.S.T.M. STANDARD METHODS OF ROUTINE ANALYSIS OF YELLOW ~ 
 
 AND ORANGE PIGMENTS CONTAINING CHROMIUM COMPOUNDS, 
 BLUE PIGMENTS AND CHROME GREEN. 
 GENERAL METHODS. 
 
 SPECIFIC GRAVITY. 
 
 1. True specific gravity shall be determined in accordance with the 
 Standard Method of Test for Specific Gravity of Pigments (Serial Designa- 
 tion: D 158) of the American Society for Testing Materials. 
 
 TINTING STRENGHT* 
 2. The colors should always be compared with a carefully selected stand- 
 ard. Weigh out accurately a portion of the color (0.02 g. of yellow; 0.01 g. 
 of green or blue), place on a large glass plate, add 24 drops of bleached lin- 
 
 seed oilf (86 drops with blues). and mix with a clean steel spatula until the 
 mass appears to be homogeneous; add pure ZnO (2 g. for yellows or greens, 
 
 3 g. for blues), and grind with a circular motion 50 times, using a flat-bottomed 
 glass pestle or muller; gather up with a sharp-edged spatula and grind out 
 twice more in like manner, giving the pestle a uniform pressure. Next weigh 
 out a similar amount of the standard, and treat in exactly the same manner 
 as described above. Transfer portions of each paste to a microscope slide, 
 quite close together, and then draw a palette knife across both samples so as 
 to make them meet in a line (differences in tint are then easily seen). Com- 
 pare the tints as shown on both sides of the glass. The amount of pigment 
 used will vary with the tinting strength, but the amounts indicated will gen- 
 erally suffice. 
 
 If it is desired to express quantitatively the tinting strength of the pig- r 
 ment, consider the standard pigment as having a tinting strength of 100, and 
 then vary the amount of the standard pigment until the tints are matched. 
 
 For example, let the amount of standard pigment for 100 strength test be § 
 0.05 g. (=A). Vary this amount in units of 5 per cent, thus 0.0475 or 0.0525. — 
 Let the amount required to match a given strength equal B, then 
 
 B 
 cae eee 
 A 
 
 equals the tinting strength of the sample to be tested. 
 If the tone varies it may be difficult to make this measurement. 
 
 *Hollep, “Analysis of Paint and Varnish Products,” 1912, p. 126. : 
 +The use of “oxidized” oil should be avoided (oil that ha sbecome “fatty” 
 by standing in a can or bottle). Poppy oil could be used but it is quite as — 
 necessary to have it reasonably fresh as when linseed oil is used. In either — 
 case “stringy” pastes are not reliable. . 
 
Yellow, Orange, Blue, and Green Pigments 737 
 
 ADDED COLORING MATTER. 
 3. Test the pigment successively with hot water, 95-per-cent ethyl alcohol, 
 and chloroform. The solutions should remain colorless. Other reagents may 
 be tried.* 
 
 METHODS OF ANALYSIS OF YELLOW AND ORANGE PIGMENTS. 
 CHROME YELLOWS, AMERICAN VERMILION, BASIC LEAD CHROMATE. 
 A pure chrome yellow should contain only lead chromate and other 
 insoluble lead compounds. 
 
 MOISTURE. 
 4. Heat 2 g. at 105°C. for two hours. The loss in weight is reported as 
 moisture. 
 
 INSOLUBLE MATTER. 
 
 5. Treat 1 g. with 25 cc. of concentrated HCl and boil for from 5 to 10 
 minutes in a covered beaker, adding about 6 drops of alcohol to the boiling 
 liquid, one at a time. Dilute to 100 ce. with hot water and boil for from 5 to 
 10 minutes (the solution should be complete). Filter the hot solution (if 
 insoluble matter is present) and wash with boiling water till washings are 
 free from lead and chlorine. Ignite the insoluble matter, weigh, and examine 
 for SiO,, BaSO,, and A1,O,. 
 
 TOTAL LEAD. 
 
 6. Add NH,OH to the filtrate from the insoluble matter (or the original 
 solution), until a faint precipitate begins to form, then add 5 cc. of concen- | 
 trated HCl (sp. gr. 1.19), dilute to 500 cc., and pass into the clear solution a 
 rapid current of H,S until all of the lead is precipitated as PbS. Let the 
 precipitate settle, filter, wash with water containing some H,S. Boil the filter 
 and precipitate with dilute HNO, until all of the lead has dissolved, filter 
 and wash thoroughly with hot water. To the filtrate, add 10 cc. of H.SO, 
 (1 : 1), evaporate until copious fumes of SO, are evolved, cool, add about 75 ec. 
 of H,O and then 75 cc. of 95-per-cent ethyl alcohol. Let stand about one hour, 
 filter on a Gooch crucible, wash with dilute alcohol, dry, ignite, and weigh as 
 PbSO,. Save the alcoholic filtrate from the PbSO,, evaporate nearly to dryness 
 and add to the filtrate from the PbS. 
 
 CHROMIUM (Iron, ALUMINUM). 
 
 7. Heat the filtrate from the PbS to expel H.S and, if iron is present, add 
 a few drops of HNO, and boil about two minutes. Render the solution just 
 alkaline with NH,OH, boil a few minutes, filter, and wash with hot 2-per-cent 
 NH,Cl solution. (If the sample contains an appreciable amount of zinc, a 
 . double precipitation should be made.) In the absence of iron and aluminum 
 this precipitate may be ignited and weighed as CroO3. If iron and aluminum 
 are present, dissolve the. NH,OH precipitate with hot dilute HCl, washing 
 the paper with hot water; evaporate to about 100 ce., cool, add NH,OH until 
 alkaline, and then add Na,O, (containing at least 90 per cent of Na,O,) 
 
 *For details consult Zerr, “Tests for Coal-Tar Colors in Aniline Lakes” 
 (English translation by C. Mayer) ; Schultz and Julius, “A Systematic Survey 
 of the Organic Coloring Matters,” Hall, “The Chemistry of Paints and Paint 
 Vehicles,” and Mulliken, “Identification of Pure Organic Compounds,” Com- 
 mercial Dyestuffs, Vol. III. ; 3 
 
738 UME Orange, Blue, and Green Pigments 
 
 in small portions to the cooled solution (10 to 12° C.) until oxidation is com- 
 plete, keeping the beaker covered. Digest until all of the chromium and 
 aluminum has been dissolved, adding more Na,O, if necessary. Filter off the 
 Fe(OH); wash thoroughly with hot water. ignite and weigh as Fe,Os; or, 
 dissolve the precipitate in HCl and determine the Fe content volumetrically. 
 Make up the filtrate from the Fe(OH), to 250 ec. in a graduated flask, and — 
 mix. Render an aliquot portion acid with H.SO,, boil to expel any free oxygen, ¥ 
 cool. add an excess of standard (NH, ),Fe(SO,),.6H,O solution and titrate — 
 back with 0.1 NV K,Cr,0, solution, using K;Fe(CN)¢ as outside indicator, ; 
 (The CrO, may also be determined by acidifying the aliquot portion with : 
 acetic acid, precipitating as PbCrO, or BaCrO,, and finally weighing on a — 
 Gooch crucible.) To determine Al,O:, make an aliquot portion of the filtrate — 
 from the Fe(OH), acid with HCl, and then just distinctly alkaline with — 
 NH,OH, heat to boiling, let settle, filter, wash with hot 2-per-cent NH,Cl solu- % 
 tion, ignite and weigh as Al,O,. If iron and aluminum are not to be determined = 
 or are present in negligible amounts, the first NH,OH precipitate may be dis- — 
 solved in dilute HCl, oxidized with Na,O,, acidified with H 28O,, boiled, and — 
 CrO, determined volumetrically. The CrO, in the absence of other oxidizing F: 
 substances, may be determined on 1 g. of the pigment by Schwartz’s method — 
 (Fresenius Quantitative Chemical Arpaia Ed. 6, Vol. 1, p. 424), or by the 4 
 persulfate method,* as follows: 
 SFor x. ys chrome yellows use an 0.25-g. sample, for ¢. p. chrome greens e 
 use an 0.5 sample, and for commercial chrome greens use a 1-g. sample. — 
 Weigh aM ee nats transfer to a 600-cc. Pyrex beaker, add 25 ec. of concen- — 
 trated H,SO,, and fume lightly on a hot plate for 3 or 4 minutes. Excessive : 
 fuming or cooking over a hot flame is neither necessary nor desirable, as it # 
 may produce the difficulty soluble anhydrous chromium sulfate. The Prussian 
 blue color is destroyed in a few minutes. Cool, cautiously dilute with water z 
 to 300 ce. stir, and heat to boiling. To the boiling solution add a small 4 
 amount of permanganate (0.5 to 1 ce. of 0.1 N KMnO,) to insure the presence ¥ 
 of some manganese. Then add to the boiling solution 10 ce. of AgNO, solution 
 (2.5 g. in enough water to make 1 liter) and 20 ec. (adding this slowly) of © 
 ammonium persulfate solution (4 g. of ammonium persulfate of full strength ee 
 dissolved in 20 ce. of water). The hot solution should show the usual perman- ~ 
 ganate color. If this color does not develop, or if it disappears, add more — 
 persulfate. When the permanganate color is permanent, continue the boiling 
 (best done on a hot plate) for 10 to 15 minutes to destroy excess persulfate. | 
 Then add 5 cc. of dilute HCl (1:3) and boil for 5 to 8 minutes to reduce the — 
 oxidized manganese. The color now should be the usual chromate yellow. — 
 Cool to above 20° C. and titrate either electrometrically with ferrous sulfate,7 4 
 or add a measured excess of ferous sulfate solution (beyond the deep grass: — 
 green color) and titrate back with 0.1 N permanganate. The first faint per- 4 
 manent darkening of the green color is taken as the end point. | 
 Correction for a blank (about 0.2 cc. of KMn0,) due to color, ete., should ~ 
 
 be made. 
 
 Exte 
 
 rr tee 
 40 a Ser. 
 
 *E. F. Hickson. Circular No. 294. Scientific Section, Am. Paint and Varnish “a 
 Manufacturers’ Assn., November, 1926. a 
 +Kelley, Journal of Industrial and Engineering Chemistry Vol. 15, p. 1058 x 
 
 (1921). 
 “ fis 
 
 ie 
 
 a: a 
 
Yellow, Orange, Blue, and Green Pigments 739 
 
 NOTES. 
 
 In commercial chrome greens containing silicates and barium sulfate, filtra- 
 tion to remove the “acid insoluble matter” after fuming the sample with acid 
 and diluting is advisable though not necessary. The end point of the sub- 
 sequent titration of the clear solution is easier to see, and there is less chance 
 for “bumping” during boiling if these are removed. 
 
 In the case of ¢c. p. greens and yellows, the solution, after fuming with 
 sulfuric acid and diluting, could be filtered and the precipitated lead sulfate 
 weighed directly for total lead. This would likewise give a clear filtrate for the 
 chromium titration. 
 
 The important precautions are to avoid overheating with sulfuric acid, and 
 to make sure that the persulfate (solid material) has not deteriorated. It 
 should contain over 90 per cent of the reagent. 
 
 ZING, CALCIUM, AND MAGNESIUM. 
 
 8. Precipitate any zine in the filtrate from the first NH,OH precipitate 
 with H,S§, filter, wash with dilute (NH,).S8, dissolve the zine sulfide in dilute 
 HCl, and determine the Zn content volumetrically by K,Fe(CN), method. In 
 the filtrate from the zinc sulfide, determine calcium by the oxalate method and 
 Magnesium as Mg.P.0O,. 
 
 SULFURIC ANDHYDRIDE. 
 
 9. Heat 1 g. of the pigment with 10 cc. of concentrated HCl until free 
 chlorine is expelled, add about 300 cc. of water and boil; filter off any insoluble 
 matter and wash thoroughly with hot water, heat to boiling, and precipitate 
 with BaCl, solution in the usual manner. Keep the solution hot while filtering 
 off the BaSO, and wash with hot water until the washings show no lead or. 
 chlorine. 
 
 CARBON DIOXIDE. 
 
 10. Determine carbon dioxide by the evolution method, using dilute HNO,, 
 free from oxides of nitrogen. 
 
 WATER-SOLUBLE MATTER. 
 
 11. Weigh 2.5 g. of the pigment and transfer to a graduated 250-ce. flask, 
 (add 100 cc. of water, and boil for 5 minutes. Dilute with water, let stand 
 until at room temperature, make up to the mark with water, mix, and let settle. 
 Filter through dry paper and discard the first 25 cc. Transfer 100 cc. of the 
 clear filtrate to a weighed dish, evaporate to dryness on a steam-bath, dry in 
 an oven at 105 to 110° C. to constant weight (30 minutes will usually suffice) ; 
 cool and weigh. 
 
 TINTING STRENGTH AND ADDED COLORING MATTER. 
 
 12. Make the test for added coloring matter and tinting strength in accord- 
 ance with Sections 2 and 3. 
 
 CALCULATIONS. 
 
 18. Calculate CrO, to PbCrO,, and SO, to PbSO, if calcium is absent. If 
 CO, is present and calcium and magnesium are absent, calculate to (PbCO,),.- 
 Pb(OH),. Report any residual Pb as PbO. If calcium is present, calculate 
 to CaCO, if CO, is also present. If calcium and SO, are present and CO, is 
 absent, calculate to CaSO,. If calcium, CO,, and SO, are present, calculate to 
 CaCO, ; any residual calcium is then calculated to CaSQ,. Report zine as ZnO. 
 
740 Yellow, Orange, Blue, and Green Pigments 
 
 METHODS OF ANALYSIS OF BLUE PIGMENTS. 
 IRON CYANIDE BLUES. (PRUSSIAN BLUE, CHINESE BLUE, ANTWERP BLUE, 
 
 Minor BLUE, BRONZE BLUE, STEEL BLUE.) 
 The analysis of these blues, as is generally the case with pigments, does 
 not necessarily give results which can be used to grade samples, the strength 
 and color tests being most important. 
 
 MOISTURBE. 
 
 14. Heat 2 g. of the pigment at 105° C. for two hours. The loss in weight 
 is reported as moisture. A “dry” Prussian blue should contain less than 7 
 per cent of moisture. 
 
 INSOLUBLE MATTER. 
 
 15. Ignite 1 g. of the pigment in a porcelain dish at a low temperature, 
 just high enough to decompose the last trace of blue, but not high enough to 
 render the iron difficulty soluble in HCl. Cool, add 15 cc. of HCl and a few 
 drops of bromine, cover with a watch glass, and digest on the steam bath; 
 wash off cover, evaporate to a syrup, add water, boil, filter, wash with hot 
 water, ignite the residue and weigh. Examine the insoluble residue for silica, 
 barium sulfate, and alumina. A pure Prussian blue should show no insoluble 
 residue. 
 
 IRON AND ALUMINUM. 
 
 16. Determine iron and aluminum in the filtrate from the insoluble matter 
 by precipitation with NH,OH in the usual manner. A double precipitation is 
 desirable. Ignite and weigh Fe,0,+Al1,0,, deduct Fe,O, (calculated from total 
 Fe), and calculate Al,O,; to Al. 
 
 CALCIUM. 
 
 17. Determine calcium in the filtrate from the Fe,O,+A1,0, by precipitation 
 with ammonium oxalate titrate with KMn0O,, or ignite and weigh as CaO. 
 Acidify the filtrate from the calcium oxalate with HCl and dilute to a definite 
 volume and mix. 
 
 SULFURIC ACID. 
 
 18. Determine sulfuric acid in an aliquot of the above solution as BaSO, 
 
 in the usual manner. 
 
 ALKALI METAL AND ALKALINE SALTS. 
 
 19. Evaporate an aliquot of the above solution with sulfuric acid, ignite 
 (treating with solid ammonium carbonate), and weigh. Determine whether 
 the alkali metal is sodium or potassium and subtract the alkali metal corres- 
 ponding to the sulfate (SO,) found. The remainder is alkali combined with 
 the blue and is reported as Na or K. 
 
 TOTAL IRON. 
 20. Decompose and dissolve 1 g. of the pigment as under “Insoluble Matter,” 
 reduce, and determine the total iron with KMnO, or K.Cr.0;,. There should 
 be not less than 30 per cent, calculated on the dry pigment. 
 
 TOTAL NITROGEN. ui 
 21. Determine the total nitrogen on a 1-g. sample of the pigment by the 
 Kjeldahl-Gunning Method, digesting: for at least 214 hours. The sulfuric acid 
 
 = 
 
 should not blacken, which would indicate organic adulteration. 
 
Yellow, Orange, Blue, and Green Pigments 741 
 
 WATER-SOLUBLE MATTER. 
 
 22. Weigh 2.5 g. of the pigment into a graduated 250-ce. flask, add 100 ce. 
 of water, and boil for five minutes. Dilute with water, let stand until at room 
 temperature, make up to mark, mix and let settle. Filter through dry paper 
 and discard the first 25 cc. Transfer 100 ce. of the clear filtrate to a weighed 
 dish, evaporate to dryness on a steam-bath, dry in an oven at 105° C. for 30 
 minutes, cool, and weigh. 
 
 TINTING STRENGTH AND ADDED COLORING MATTER. 
 
 23. Make the test for added coloring matter and tinting strength in 
 accordance with Sections 2 and 3, omitting the treatment with hot water. 
 Also test the pigment with dilute acid for ultramarine blue (evolution of 
 hydrogen sulfide) and carbonates (evolution of carbon dioxide.) 
 
 CALCULATIONS. 
 
 24. The percentage of Prussian blue may be obtained with sufficient 
 accuracy for commercial purposes by multiplying the percentage of nitrogen 
 by 4.4 or the percentage of iron (in the absence of other iron pigments) by 
 3.03.* 
 
 NoTE.—Some blues, e. g., Chinese blue, may contain tin salts. Others may 
 contain manganese or chromium compounds. The presence of these compounds 
 should be determined by a qualitative examination at least. 
 
 METHODS OF ANALYSIS OF ULTRAMARINE : BLUE. 
 
 An analysis is of little value for determining the quality of pure ultra- 
 
 marines, but is useful in the identification of foreign admixtures. Practical 
 
 tests as to the stability and compatability of the pigment in mixtures with 
 
 other pigments, coloring power, -tint, fineness, fastness to light, etc., are more 
 important than chemical analysis. 
 
 MOISTURE. 
 25. Heat 2 g. of the pigment at 105° C. for two hours, cool and weigh. 
 The loss in weight is reported as moisture. 
 
 SILICA. 
 
 26. Treat 1 g. of the pigment in a covered dish or casserole with 30 ce. 
 of HCl (1:1), heat until decomposed, wash off and remove cover, and 
 evaporate to dryness on the steam-bath. Moisten with concentrated HCl and 
 again evaporate to dryness, add 1 to 2 cc. of concentrated HCl, let stand about 
 5 minutes, add hot water, filter and wash the insoluble matter with hot water. 
 If great accuracy is desired, evaporate the filtrate to dryness, take up with 
 HCl and water, filter on a second paper, wash, and add the residue to the 
 main insoluble. Ignite the insoluble matter, cool and weigh. Determine SiO, 
 by volatilization with H,SO, and HF. Make a qualitative examination of any 
 residue that may remain. 
 
 ALUMINA. 
 
 27. Render the filtrate from the silica faintly alkaline with NH,OH, boil a 
 
 few minutes, filter, wash with hot 2-per-cent NH,Cl solution, ignite and weigh 
 
 od 
 
 *Parry and Coste, The Analyst, Vol. 21, pp. 225 to 230 (1896). 
 
742 Yellow, Orange, Blue, and Green Pigments 
 
 as Al,O,(+Fe,0,). For more accurate work, dissolve the Al(OH), precipitate 
 in HCl and reprecipitate as above. 
 
 SODIUM OXIDE. 
 
 28. Acidify the filtrate from the Al,0O, with H,SO,, evaporate to dryness, 
 ignite (finally adding solid ammonium carbonate) and weigh as Na,SO,. 
 Calculate to NaeO. If calcium is present it should be precipitated with 
 ammonium oxalate in the filtrate from the Al,O,, ignited and weighed as CaO, 
 and the sodium determined in the filtrate from the calcium oxalate, as 
 described. 
 
 TOTAL SULFUR. 
 
 29. Mix 1 g. of the ultramarine with 4 g. of Na.,CO, and 4 g. of Na,O, in a 
 nickel crucible, cover with about 1 g. of Na.CO, and fuse, using an aluminum 
 or asbestos shield to prevent the sulfur being taken up from the gas. Dissolve 
 the fused mass in dilute HCl, filter and wash, if necessary (there should be 
 no insoluble residue), precipitate with BaCl, and determine total sulfur e 
 weighing as BaSO, Calculate to S. 
 
 SULFUR PRESENT AS SULFATE. 
 
 30. Dissolve 1 g. of the pigment in dilute HCl, boil to expel H,S, and filter 
 if necessary; make the solution faintly alkaline, with NH,OH and just 
 distinctly acid with HCl, and treat with BaCl, in the usual manner. Calculate 
 BaSO, to SO, and'to §S. 
 
 SULFUR PRESENT AS SULFIDE. 
 31. Subtract the sulfur present as sulfate from the total sulfur. 
 
 a 
 
 METHODS OF ANALYSIS OF COBALT BLUE* 
 
 This pigment is essentially a compound of the oxides of aluminum and 
 
 cobalt. Certain shades of ultramarine blue are often sold under the name 
 “cobalt blue.” 
 MOISTURE. 
 32. Heat 2 g. of the pigment at 105° C. for 2 hours. The loss in weight is 
 reported as moisture. 
 ALUMINA. 
 33. Fuse 1 g. of the pigment with 12 to 15 g. of sodium or potassium pyro- 
 sulfate, cool, digest with water and HCl, filter, and wash the residue with 
 hot water. Make the filtrate up to 250 cc. in a graduated flask and mix. 
 
 Sg J 
 
 ee ee ae ee 
 
 Ignite the residue, cool, weigh, and examine for SiO, and BaSO, Dilute an 
 
 aliquot portion of the filtrate to 200 cc., add 5 g. of NH,Cl, heat to boiling, and ~ 
 
 add dilute NH,OH till just distinctly alkaline (a few drops of 0.2-per-cent 
 
 alcoholic solution of methyl red is recommended as indicator). Boil for one Ss 
 
 or two minutes, filter at once, dissolve the precipitate with HCl, and reprecipi- 
 
 tate as before. Filter, wash thoroughly with hot 2-per-cent NH,Cl (or — 
 
 NH,NO,) solution, ignite, and weigh as AI,O,. 
 
 CALCIUM. AND MAGNESIUM. 
 
 34. Unite the filtrates from the A1,O,, saturate with hydrogen sulfide, filter, % 
 
 and determine calcium and magnesium in the filtrate in the usual manner. ~ 
 
 *“ Analysis of: Paint-and Varnish Produce ’ by C. D. Holley, p. 210 (1912). * 
 
Yellow, Orange, Blue, and Green Pigments 743 
 
 vn ea nEEEEEEEEEEEIEEIEEIIEEEEIEIRIEIEI IEEE Ee 
 
 COBALT OXIDES. 
 
 35. Subtract the determined constituents from 100 and report the difference 
 as cobalt oxides, unless a qualitative examination shows the presence of other 
 substances in significant amounts. Should the pigment contain phosphoric 
 acid (or arsenic acid) in more than negligible amounts, these must be removed 
 before determining aluminum, calcium and magnesium.* 
 
 METHODS OF ANALYSIS OF SUBLIMATED BLUE LEAD.{ 
 TOTAL LEAD. 
 
 36. Digest 1 g. of the sample with 15 cc. of concentrated HNO, in a covered 
 beaker. Boil the solution until the brown fumes of the oxides of nitrogen 
 have disappeared. Add 6 cc. of concentrated H,SO, and again boil until the 
 heavy fumes of SO, are evolved. Allow the solution to cool, add 30 ce. of 
 water and boil. Remove the beaker from the hot plate and allow the solu- 
 tion to stand for from 3 to 4 hours. Filter the solution, washing the precipi- 
 tate by decantation 3 or 4 times and allowing the bulk of the precipitate 
 to remain in the beaker. Place this beaker containing the residual lead sulfate 
 under the funnel used for the filtration, wash the filter paper with 75 cc. of 
 a mixture consisting of 95 ec. of NH,OH (sp. gr. 0.80), 125 ec. of 80-per-cent 
 acetic acid and 100 ce. of water. Follow this washing with 75 ce. of hot 
 water. Boil until all PbSO, is dissolved. Dilute to 200 ce. with hot water, 
 boil and titrate with standard ammonium molybdate solution, using a freshly 
 prepared solution of one part of tannic acid in 300 parts of water as an out- 
 side indicator. Run a blank and correct for same. The ammonium molybdate 
 solution contains 8.67 g. in one liter of water and is standardized against pure — 
 lead foil, pure PbO, or pure PbSQ,. 
 
 TOTAL SULFUR. 
 
 37. Treat 0.5 g. of the sample in a beaker with 10 cc. of water and a few 
 ce. of bromine water. Boil gently until all the bromine has passed off. Dilute 
 with water, add another portion of bromine water, boil, and continue the 
 treatment until the sediment has become white in color. Add 8 cc. of HNO), 
 evaporate the solution until the brown fumes of nitric acid have disappeared, 
 dilute with water and add an excess of Na.CO;. Boil gently (covered) for 
 from 10 to 15 minutes and let stand for 4 hours. Dilute with hot water, 
 filter, and wash with hot water. Reject the residue. Acidify the filtrate 
 (about 200 cc.) with HCl and add an excess of about 2 cc. of the acid. Boil 
 and add a slight excess of 10-per-cent barium chloride solution. Let stand 
 on a steam-bath about 1 hour, filter, wash with hot water, ignite, and weigh 
 as BaSO,. Calculate the BaSO, to 8. 
 
 LEAD SULFATE. 
 38. On a separate sample determine the sulfate directly with Na.CO, as in 
 the preceding paragraph, without any preliminary treatment with bromine 
 water. 
 
 *See “Technical Methods of Chemical Analysis.” Lunge-Keane, Vol. III, 
 Part II, p. 978 (1914). 
 
 *“The Chemical Analysis of Lead and its Compounds.” Schaeffer and 
 White, pp. 22 to 24. 
 
744 Yellow, Orange, Blue, and Green Pigments 
 
 LEAD SULFITE. 
 
 39. Boil 1.5 g. of the sample with 3 g. of Na,CO,, let stand, filter, and wash 
 
 thoroughly. To the filtrate add 38 cc. of bromine water, heat gently to oxidize 
 the sulphite to sulfate, acidfy with HCl, and precipitate with BaCl, solution. 
 Filter, wash, ignite, and weigh as BaSO, Deduct the amount present as 
 sulfate and calculate the remainder to lead sulfite. 
 
 LEAD SULFIDE. 
 40. Deduct the sulfur present as sulfate and sulfite from the total sulfur 
 and report the difference as lead sulfide. 
 
 LEAD CARBONATE. 
 41. Determine any CO, present by the evolution method, removing any 
 
 aaeneA 7 ae 
 
 HeS or SO, formed by means of KMnOy, or CrOs solution. Calculate to PbCO,. ~ 
 
 LEAD OXIDE. 
 42. Deduct the lead present as sulfate, sulfite, sulfide, and carbonate from 
 the total lead and report the difference as lead oxide (PbO). 
 
 ZINC OXIDE. 
 43. Boil 1 g. of the sample with a solution of 4 g. of NH,Cl in 30 ce. of 
 
 water plus 6 cc. of concentrated HCl. Dilute to 200 cc. with hot water, add 
 
 2 ee. of a saturated sodium thiosulfate solution, and titrate with a standard 
 solution of potassium ferrocyanide, using a 5-per-cent solution of a uranium 
 nitrate as an outside indicator. Report as ZnO. 
 
 CARBON AND VOLATILE MATTER. 
 44. Ignite a weighed portion of the sample in a partially covered crucible 
 at a low red heat for 2 hours, cool, and weigh. Report the loss in weight 
 as carbon and volatile matter. 
 
 METHODS OF ANALYSIS OF GREEN PIGMENTS. 
 ( CHROME GREEN) 
 
 A pure chrome green should contain only Prussian blue and pure chrome ~ 
 
 yellow. A microscopic examination should be made to determine whether the 
 green is a combined precipitation product, which is of the greater value, or 
 
 one mixed after separate precipitation. A good green will show the presence ~ 
 
 ony . ad sarah ee ee ee 
 iain eel PRON A AS oT Se RY 
 
 Ae Ati Sehr olay pes 
 
 of green and blue particles, while a poor green will show yellow and blue ~ : 
 
 particles mixed with green. 
 MOISTURE. 
 
 45. Heat 2 g. of the pigment at 105° C. for two hours. The loss in weight — 
 
 is reported as moisture. 
 INSOLUBLE MATTER. 
 
 46. Heat gently 1 g. of the pigment in a small porcelain dish until the blue . 
 
 color has been decomposed. The heating should be carried out very carefully 
 so as not to render the iron difficulty soluble. (With some very pure chrome 
 greens it may be advantageous to mix the sample with 2 to 5 times its weight 
 
 of pure barium sulfate before igniting.) Let cool, transfer to a beaker, and 
 
 determine insoluble matter as outlined in Section 5 for Yellow Pigments. 
 
 LEAD. 
 
 47. Determine lead in the filtrate from the above as outlined in Section — 
 
 6 for Yellow Pigments. 
 
Yellow, Orange, Blue, and Green Pigments 745 
 
 IRON, ALUMINA AND CHROMIUM. 
 48. Determine iron, aluminum and chromium in the filtrate from the PbS 
 as outlined in Section 7 for Yellow Pigments, making a double precipitation. 
 
 ZINC, CALCIUM, AND MAGNESIUM. 
 49. Determine zinc, calcium and magnesium in the filtrate from the iron, 
 aluminum and chromium determination as outlined in Section 8 for Yellow 
 Pigments. 
 
 CARBON DIOXIDE. 
 
 50. Determine carbon dioxide by the evolution method, using dilute HNO, 
 ast) 
 
 SULFURIC ANHYDRIDE. 
 
 51. Heat gently 1 g. of the pigment as in Section 46, cool, transfer to a 
 beaker, add 30 cc. of concentrated HCl, cover, and heat on a steam-bath for 
 about 380 minutes (in some cases, the iron compounds will go into solution 
 more readily by letting the solution stand for some time at room temperature 
 and then heating). Wash off cover, add 50 cc. of boiling water, boil for five 
 minutes, filter, render the filtrate faintly alkaline with NH,OH, then slightly 
 acid with HCl, heat to boiling, and precipitate with BaCle (15 ec. of 10-per-cent 
 solution) in the usual manner, boiling about ten minutes. Filter, wash with 
 hot water, ignite, and weigh the BaSQ,. 
 
 NITROGEN. 
 52. Determine nitrogen on a 1-g. portion of the pigment by the Kjeldahl- 
 Gunning Method, digesting for at least 214 hours. 
 
 WATER-SOLUBLE MATTER. 
 
 53. Weigh 2.5 g. of the pigment into a graduated 250-ce. flask, add 100 ce. 
 of water, and boil for five minutes. Dilute with water, let stand until at 
 room temperature, make up to the mark, mix, and let settle. Filter through 
 dry paper and discard the first 25 cc. Transfer 100 ce. of the clear filtrate to 
 a weighed dish, evaporate to dryness on a steam-bath, dry in an oven at 
 105° C. for 30 minutes, cool and weigh. 
 
 TINTING STRENGTH AND ADDED COLORING MATTER. 
 54, Make the test for added coloring matter and tinting strength in accord- 
 ance with Sections 2 and 3. Also test the pigment with dilute acid for the 
 presence of ultramarine blue (evolution of hydrogen sulfide). 
 
 Hickson’s Peroxide Method for Chrome Green Analysis. 
 K. F. Hickson of the Bureau of Standards has studied the 
 analysis of chrome green pigments and his conclusions are 
 published in Scientific Section Circular No. 294. Several of 
 his recommendations have been embodied in the A. S. T. M. 
 procedure given above, the most important being the use of 
 Na2O2 containing at least 90 per cent of the reagent. He also 
 recommends the addition of peroxide to a cold solution, 10- 
 12° C. The writer has also found these precautions of 
 value. 
 
746 Yellow, Orange, Blue, and Green Pigments 
 
 ee ee ee eee ene ee a a 
 
 Brown’s Method for Chrome Green Analysis. A. F. Brown 
 
 in a private communication has submitted his methods for 
 the analysis of chrome green either pure or reduced. It is 
 
 believed that these methods are well worth consideration. — 
 
 They are given below: 
 
 Heat 2 grams of pigment at 110° C. for two hours. - Loss in ~ 
 
 weight is reported as moisture. 
 
 1 gr. pigment is weighed into a 250 ce. Pyrex beaker, cover ~ 
 with watch-glass, decompose the pigment by placing beaker : 
 on an electric hot- plate (about 250° C.) until the color is — 
 destroved. (With pure or C. P. colors (to prevent ignition) — 
 add 2 to 5 grams of dry Na.CO, mixing thoroughly with stir- 
 ring rod). (Cool beaker, carefully treat with about 25 cc. conc 
 HCl and a little KC1O;, boil about 5 minutes, dilute to 100 ee. ~ 
 and filter off any insoluble matter, washing thoroughly with ~ 
 hot water. This insoluble matter combined with any BaSOs — 
 found below is ignited in a platinum crucible, cooled and — 
 weighed. Add about 10 grs. Na,CO,-K,CO; (1-1) heat to a_ 
 clear fusion, cool, digest with water, filter off any insoluble © 
 matter washing with hot water containing a little Na.CO;;_ 
 evaporate alkaline filtrate to small volume. Dissolve insolu-— 
 ble matter on paper (also in beaker and crucible) in hot ~ 
 dilute HCl and precipitate the Ba with H2SO, (1:1). Digest ~ 
 
 BaSoO,, filter, ignite and weigh. Evaporate this acid filtrate 
 
 to small ole and eapetiiis combine with the alkaline fil-@ 
 
 trate from fusion, acidify with HCl if necessary, evaporate — 
 
 as dry as possible, take up with dilute HCl, filter off any SiOs — 
 and determine Al and Mg in filtrate. If Al and SiO. are pres- — 
 
 ent calculate to clay, using the theoretical formula, Al.O;.- 
 
 2810..2H.O. The Be found represents the BaSO, ‘present 
 
 probably as barytes. 
 
 Nearly neutralize insoluble matter filtrate (or original solu-— 
 
 tion) with NH,OH, dilute to about 300 ec. and pass in H, S 
 until all Pb is precipisated: Filter off the PbS on a Gooch, - 
 washing thoroughly. Transfer PbS and asbestos to originally 
 
 beaker, pour hot (1-1) HNO; through Gooch into the beaker — 
 
 with the PbS to dissolve any PbS on “the crucible. Digest PbS — 
 in beaker until black PbS is all dissolved. Filter off the 
 asbestos and sulfur, through a thin mat of asbestos on the - 
 Gooch. Add (1-1) H2S80. to ‘the clear hot filtrate and evaporate — 
 to SOs fumes. Cool, dilute to about 100 ce., let stand about an ~ 
 
 hour, filter on Gooch, wash with dilute HS80a, dry, ignite and 
 
 weigh as PbSOs. 
 
Yellow, Orange, Blue, and Green Pigments 747 
 
 ey 
 
 Add about 10 ee. (1-1) HeSOs to above PbS filtrate, digest 
 about an hour to expel H.S and to precipitate any BaSQ, dis- 
 solved from the insoluble matter. If a precipitate is obtained 
 at this point, filter off, and combine with the insoluble matter 
 as mentioned above. The filtrate is made slightly ammoniacal; 
 digest on hot-plate until hydroxides separate clear; filter, 
 wash with hot water. Determine any Ca, Mg or Zn in the 
 filtrate. Redissolve the hydroxides on fe filter paper by 
 pouring through about 25 ce. boiling (1-1) HCl, catching 
 the filtrate in a 250 ce. volumetric flask, further Wash the filter 
 paper with hot dilute HCl until clean, finish with hot water. 
 Cool the flask and dilute to the mark. Pipette out two 100 ce. 
 portions of this solution. Make one portion slightly ammo- 
 niacal, digest, filter, ignite and weigh as total oxides. Make 
 the other portion slightly alkaline by adding small pieces of 
 e.p. NaOH (sticks), cool thoroughly, add about iets e Na Ol 
 heat to boiling and boil a few minutes to remove the H.O.. 
 Filter off the Fe(OH)s, washing with hot water, evavorate the 
 filtrate containing the chromium in about 100 ce, Redissolve 
 the Fe(OH)s by pouring 25 ce. boiling (1-1) HC! on to the filter 
 paper, catching the filtrate in the original beaker. Heat the 
 Fe solution nearly to boiling and add from a pipette, drop by 
 drop, some 10 per cent SnCl. until the solution becomes prac- 
 tically colorless. Adda few drops in excess. Cool thoroughly, 
 add about 15 ec. of saturated SnCl., a hazy, white precipi- 
 tate HgCl should appear after a little stirring, if not, not 
 enough SnCl, was added. Add about 10 ec. H.SO,-H,PO, 
 (1-1) and four drops of diphenylamine indicator (1 gram salt 
 in 100 ee. conc. H.8O,). Titrate with N/10 K.Cr20; to a deep 
 blue (starch-iodine color), calculate to FeO; and iron blue 
 (Fe X 3.03). Acidify the chromium solution with HeSOs- 
 H;PO, (1-1), add an excess of N/10 (NH,). Fe(SO,)2.6H2O and 
 four drops diphenylamine indicator, titrate back with 
 N/10 KeCr20,. Run a blank on the N/10 (NH,)> Fe (SO,) 6H20. 
 Calculate results to Cr,O3 and PbCrOs. The chromium may 
 also be determined by adding about 20 ce. of 10 per cent 
 KI to the alkaline chromium solution, in an iodine flask, mak- 
 Ing acid with cone. HCl, and after ten minutes, titrating back 
 with N/10 Na.S.O, using starch solution as an ee Rioe. The 
 sum of the Fe,O3 and Cr.Os found, subtracted from the total 
 oxides gives the Al.Os, if any. 
 
 Ignite 1 gram sample as indicated under insoluble matter, 
 
 dissolve in about 10 ce. cone. HCl by boiling, dilute to about 
 100 ce., filter off any insoluble matter while hot, washing with 
 
748 Yellow, Orange, Blue, and Green Pigments 
 
 lene re : 
 
 hot water. Heat to boiling, add about 15 ee. of 10 per cent — 
 BaCl, and digest about 2 hours, better overnight if SOs is — 
 small. Filter BaSOs hot, washing thoroughly with hot water. — 
 This method is probably not very accurate in the case of a © 
 reduced green, especially when barytes and China Clay have_ 
 been used as extenders and in the presence of iron salts since — 
 under these conditions a small amount of the extenders will 
 ¢o into solution and may be thrown out on dilution or on add-~ 
 ing the BaCl. 
 
 Digest a 1 gram sample in about 200 ce. hot water (about — 
 85° C.) for about 2 hours, filter on Gooch, dry at 110° C., cool 
 and weigh. Loss in weight, corrected for the moisture found 
 above, represents the water soluble salts. 
 
 Digest a 1 gram sample in about 200 ee. hot water containing 
 10 ce. glacial acetic acid for about 2 hours. Filter on Gooch, 
 nearly neutralize the hot acetic acid filtrate with NH,sOH, add 
 an excess of K,Cr.0O, solution, digest until PbCrO, settles” 
 clear. Filter on Gooch, wash the precipitate thoroughly with — 
 hot water and finally with a little aleohol. Dry at 110° C., cool — 
 and weigh. If CO, is present in the pigment, as shown by an 
 effervescence when some is sprinkled upon acid in a watch- 
 glass, and Ca and Mg are absent, calculate the acetic soluble 
 Pb to Pb(COs)..Pb(OH).. If no COse is present the acetic 
 soluble Pb may represent the PbO of a basic PbCrOs or other 
 acetic acid soluble lead compound. ¥ 
 
 Calculate CrO3 to PbCrOs, and SOs to PbSOs if Ca is absent. 
 If CO, is present and Ca and Mg are absent, calculate to 
 (PbCOs)2. Pb(OH)»2. Report any residual Pb. as checked 
 by the acetic soluble determination, as PbO. If Ca is present, 
 caleulate to CaCOs if COz is also present. If Ca and SOs: are 
 present and COz is absent, calculate to CaSOs. If Ca, CO. and 
 SOs are present, calculate to CaCOs; any residual Ca is then 
 calculated to CaSOs. Report Zn as ZnO. Fe X 3.03 (in the © 
 absence of other iron pigments) represents the iron blue 
 present. 
 
 Zinc Chromate Analysis. The insoluble matter may be 
 determined as on chrome greens (page 737). 
 
 Zinc.—The filtrate from the insoluble matter is made alka- 
 line with NaOH and then treated with H2S. The ZnS is filtered 
 off, dissolved in HCl and the Zn determined by any desirable 
 method. 
 
 Chromium.—tThe filtrate from the ZnS precipitate contains 
 the chromium, which may be determined as in chrome greens. 
 
Yellow, Orange, Blue, and Green Pigments 749 
 
 The solution is first acidified with HCl and boiled to remove 
 the H2S, after which the procedure on page 737 may be fol- 
 lowed. 
 
 Chromic Oxide Green Analysis. The important determi- 
 nation on this pigment is the chromium oxide content, the 
 chromium being determined as on page 737. The pigment is 
 brought into solution by the method of Scott.* 0.5 gram of pig- 
 ment is fused gently in an iron or nickel crucible with 2 or 3 
 grams fresh Na.O, for 15 minutes. 1 gram of NazOz is added 
 and the fusion continued for 5-10 minutes longer. The melt is 
 digested in 100 ec. of boiling water for 10-15 minutes and 5 
 grams of (NH,).CO; are added to neutralize the free alkali. 
 The solution is filtered hot and the chromium in the filtrate 
 determined. 
 
 Miscellaneous Pigments. The methods given above cover 
 practically all commonly used pigments found in commercial 
 paints. There are, however, a number of rare pigments used 
 to a small extent in artists’ colors. Among these may be 
 mentioned blues containing arsenates or phosphates, Guignet’s 
 green, green earth, copper greens and cobalt greens. The 
 methods for the analysis of many of these are discussed in| 
 “The Analysis of Pigments, Paints, and Varnishes’’ by Fox 
 and Bowles.t 
 
 AS.T.M. TENTATIVE SPECIFICATIONS FOR PURE CHROME GREEN. 
 
 1. These specifications cover what is commercially known as pure chrome 
 green. The pigment may be purchased in the dry form or ground in oil or in 
 japan to form a paste. 
 
 I. MANUFACTURE. 
 
 2. (a) Dry Pigment.—The pigment ‘shall be a precipitated mixture of lead 
 chromate and iron ferro and ferricyanide blue, with or without other insoluble 
 compounds of lead. 
 
 (b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
 the specified pigment with pure raw or refined linseed oil. ; 
 
 (c) Paste in Japan.—The paste in japan shall be made by thoroughly 
 grinding the specified pigment with high-grade grinding japan. 
 
 II. PROPERTIES AND TESTS. 
 
 3. (@) The mass color and character of the tint formed by mixture with 
 
 a white pigment shall be the same as, and the strength not less than, that 
 of a sample mutually agreed upon by buyer and seller. 
 
 * Scott. Standard Methods of Chemical Analysis, p. 157. 
 TD. Van Nostrand, 1927. 
 
750 Yellow, Orange, Blue, and Green Pigments 
 
 (b) Dry Pigment.—The dry pigment shall meet the following requirements: 
 
 Percentage of total lead present in the form of chromate, mini- 
 
 TUM) ©. fc oe bc eb oe wre ne Wak 0-0 ole wim 5 lal i nae tet ee lagen 70 
 Total impurities, maximum, per CeNt.......-- seer eeeeeeeeceres 3 
 Coarse particles (total residue retained on a No. 325 screen), 
 
 MAXIMUM, PEL CEN 1... eee ee sere e eee reeeerereerssescerers 
 
 (c) Paste in Oil.—The paste as received shall not be caked in the container — 
 and shall break up readily in oil to form a smooth paint of brushing con- | 
 sistency. It shall mix readily in all proportions, without curdling, with lin- 
 seed oil, turpentine, or volatile mineral spirits, or any combination of these — 
 substances. The paste shall meet the following requirements: 
 
 Pigment, minimum, per Cent... -... eee eeeeee cee ere creer recres 70 
 
 Linseed oil, maximum, per CeNt...... cee eee eee rc ere eeceerarenes 30: 
 
 Coarse particles and skins (total residue retained on a No. 325 
 screen), maximum, per cent of the pigment..........-+++++- 1.5 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the con- — 
 tainer and shall break up readily in turpentine to form a smooth paint of © 
 brushing consistency that will dry within one hour to a hard, flat coat that 
 can be varnished within 5 hours of the time of application without streaking — 
 or bleeding. The paste shall meet the following requirements : 
 
 Pigment, minimum, per CEN... 1... eee eer cere cere rece ree eneeees 65 
 
 Vehicle (japan), maximum, per CeNt....-.+eeseeeeereeesereess 35 
 
 Coarse particles and skins (total residue retained on a No. 3825 
 screen) maximum, per cent of the pigment.............-.-. 1.5 : 
 
 Non-volatile matter in vehicle, minimum, per cent of the vehicle 40 
 
 4. One sample shall be taken at random from each lot of 1000 packages : 
 or less. If the packages are of such size that 1000 packages amount to more q 
 than a carload, one sample shall be taken at random from each ecarload. 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR REDUCED CHROME : 
 
 : xf 
 
 GREEN 
 
 1. These specifications cover what is known commercially as reduced — 
 chrome green, also known as grinders green. The pigment may be purchased — 
 
 in the dry form or ground in oil or in japan to form a paste. 
 
 I. MANUFACTURE. f 
 
 2. (a) Dry Pigment—The pigment shall be a mixture of lead chromate — 
 and iron ferro and ferricyanide blue, with or without other insoluble com- i 
 pounds of lead, precipitated on a base of barium sulfate or insoluble siliceous i: 
 material or any mixture thereof. a 
 (b) Paste in Oil—The paste in oil shall be made by thoroughly grinding — 
 the specified pigment with pure raw or refined linseed oil. : i 
 (c) Paste in Japan—The paste in japan shall be made by thoroughly | 
 grinding the specified pigment in high-grade grinding japan. 
 
 i 
 
 II. PROPERTIES AND TESTS. ‘ 
 8. («) The mass color and character of the tint formed by mixture with = 
 
Yellow, Orange, Blue, and Green Pigments 751 
 
 a white pigment shall be the same as, and the strength not less than, that of 
 a sample mutually agreed upon by buyer and seller. 
 (b) The dry pigment shall meet the following requirements: 
 
 MAXIMUM MINIMUM 
 Sum of the barium sulfate and insoluble. siliceous 
 
 BRIA OTIGONG hoc os fcc. hes sch sed vuneceseaces 80 
 Color (total of insoluble lead compounds: and iron 
 
 2 SESS ol 20, is ee itis 20 
 Percentage of total lead present in the form of chromate .... TO 
 Total calcium oxide in any form soluble in acid, per 
 
 eR eae eel yas eo ive a's 8 sb geace’s coe as eccos ds 1.0 
 Coarse particles (total residue retained on a No. 325 
 
 AMES TENE re eae, fopice ao el'x xxl! «6 0.4 te oe: wie wa adelele's 1.5 
 
 (c) Paste in Oil.—The paste as received shall not be caked in the container 
 and shall break up readily in oil to form a smooth paint of brushing con- 
 sistency. It shall mix readily in all proportions without curdling, with linseed 
 oil, turpentine, or volatile mineral spirits, or any combination of these sub- 
 stances. The paste shall meet the following requirements: 
 
 CREDIT FOr! CNL oi. se kc oes oa ares a wt vie ce cae an come SO 
 
 Pee AMIN Per CONt. 66s. ck ck kh ae sw ece debian 20 
 
 Coarse particles and skins (total residue retained on a No. 325 
 screen), maximum, per cent of the pigment................. 2.0 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the con- 
 tainer and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency that will dry within one hour to a hard flat coat that can 
 be varnished within 5 hours of the time of application without: streaking or 
 bleeding. It shall meet the following requirements: 
 
 PEPER NINAITIN’ PCT © CONG 5:0. 5:0 c cos Sade we ac ce weneccvecen bes T5 
 
 Peete (japan), Maximum, per cent...........0. ccc ce see we ee’ 25 
 
 Coarse particles and skins (total residue retained on a No. 325 
 meen ena SITUIM PET CONG. <6. 5 oa oss eleeis eo oo bo otve wale vedas 2.0 
 
 Non-volatile matter in vehicle, minimum, per cent of the vehicle 40 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR CHROME OXIDE GREEN 
 
 1. These specifications cover the pigment commonly known as chrome oxide 
 green. The pigment may be purchased in the dry form or ground in oil to 
 form a paste. 
 
 MANUFACTURE. 
 
 2. (a) Dry Pigment.—The dry pigment shall consist of practically pure 
 sesqui-oxide of chromium (Cr,0O,) without any admixture. 
 
 (6) Paste.—The paste shall be made by thoroughly grinding the specified 
 pigment in pure raw or refined linseed oil. 
 
 PROPERTIES AND TESTS. 
 ’ 5. (@) The mass color and character of the tint formed by mixture with 
 a white pigment shall be the same as, and the strength shall be not less than 
 that of a sample mutually agreed upon by the buyer and seller. 
 
752 Yellow, Orange, Blue, and Green Pigments 
 
 (b) Dry Pigment.—The dry pigment shall conform to the following Ps 
 requirements | ~ 
 
 Total chromium (ealeulated as Cr ,O), minimum, per cent,..... 97,0 
 Coarse particles (total residue retained on a No, 826 screen), 
 maximum, per CODTs saa he seeee eeeaeeveeeeee eee eeeoe eevee eeeeenen @ . 
 
 (¢) Paste Phe paste as received shall not be caked in the container and “ 
 shall break up readily in off to form a smooth paint of brushing consistency. % 
 It shall mix readily, in all proportions, without curdling, with linseed oil, 4 
 turpentine or volatile mineral spirits, or any mixtures of these substances, — 
 The paste shall conform to the following requirements ; ‘ 
 
 MAXIMUM MINIMUM 
 
 Pigment, per cent..... SOPTURenETT Its) 8 
 Linseed oll, per CeNt....esee6. ose 0:90 65. . 
 Coarse particles and aking (total ‘residue retained on 
 
 a No, 825 sereen, based on plement), per cent.... 2.5 « 
 
 4, One sample shall be taken at random from each lot of 1000 packages — 
 or fraction thereof, Tf the packages are of such size that 1000 packages } 
 amount to more than a carload, one sample shall be taken at random from 
 each eartoad, 
 
 AS'R.M. TENTATIVE SPECIFICATIONS FOR ULTRAMARINE BLUE 
 1, These specifications cover the pigment commonly known as ultramarine — 
 blue, It may be purchased in the dry form or ground in oil or in japan to | 
 form a paste, 
 MANUFACTURER, 
 
 2, (a) Dry Pigment.—The dry pigment shall be a manufactured blue | 
 approximating the composition of natural lapis lazuli, It shall be finely — 
 ground and of good blue color and free from admixtures of other substances, — 
 (0) Paste in Oil——The paste in oil shall be made by thoroughly grinding ‘ 
 the specitied pigment in pure raw or refined linseed oil, s 
 (¢) Paste in Japan.—The paste in japan shall be made by thoroughly E 
 grinding the specified pigment in high-grade grinding japan, . 
 
 PROPERTIES AND TESTS, 
 
 8. Gi) The mass color and character of the tint formed by mixture with — 
 
 a white plement shall be the same as, and the strength not less than, that of — 
 a simple mutually agreed upon by the buyer and seller, b 
 (v0) Dry Pigment.—The dry pigment shall conform to the following — 
 requirements | 
 
 Coarse particles (total residue retained on a No, 825 sereen), 
 maximum, per CONE c's a's 0 4 0-0) ba eu bb 8k bent ere er gee cn . 
 
 (c) Paste in Oil—The paste in ofl as received shall not be caked in the 
 container and shall break up readily in ofl to form a smooth paint of brushing - 
 consistency, It shall mix readily in all proportions, without curdling, with — 
 Linseed oll, turpentine or volatile mineral spirits, or any mixture of these — 
 substances, The paste shall conform to the following requirements; } 
 
Yellow, Orange, Blue, and Green Pigments 753 
 
 MAXIMUM MINIMUM 
 
 POU MCOTER Ey ce yok eas ce cence Cteccseces’e sage 70.0 
 PES PTOLICEIIGS si dels rece es ce ceedsseecceeuns 30.0 
 Moisture and other volatile matter, per cent......... 0.7 
 Coarse particles and skins (total residue retained on a 
 No. 325 screen), per cent....... Pete ats ataiets Been ate 1.5 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the 
 container and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency, that will dry within one hour to a hard flat coat that 
 can be varnished within five hours of the time of application without streaking 
 or bleeding. The paste shall conform to the following requirements : 
 
 MAXIMUM MINIMUM 
 
 ETRE OE MOOG Solas siae sla scl c se cc ccesveceave iy 70.0 
 Pemrroree JAAN) PEL CENL. oe pecs cc cee nncess 30.0 
 Coarse particles and skins (total residue retained on a 
 
 Rime esc reen ). Per CONG. «6. es eee e ce wee ees aa) 
 Non-volatile matter in the vehicle, per cent of the 
 
 SENG hei als ga ielg ¢ 4 pte \sj0 ¢:0,v'b.0i0'0 wee eee eee. Se 40.0 
 
 Nore.—The physical properties and tests of ultramarine blue, particularly 
 the tinting strength, are considered a better measure of value than the per- 
 centage of chemical constituents. 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 
 or fraction thereof. If the packages are of such size that 1000 amount to 
 more than a carload, one sample shall be taken at random from each carload. 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
 CHROME YELLOW 
 
 1. These specifications cover the pigments commonly known as lemon 
 chrome yellow, medium chrome yellow, and orange chrome yellow. The pig- 
 ment may be purchased in the dry form or ground in oil, or in japan, to form 
 a paste. 
 
 I. MANUFACTURE. 
 
 2. (a) Dry Pigments.—The dry pigments shall be chemical precipitates 
 consisting of normal or basic lead chromates or mixtures of these with or 
 without admixtures of other insoluble compounds of lead, but without any 
 other admixtures. 
 
 (b) Pastes in Oil.—The pastes in oil shall be made by thoroughly grinding 
 the specified pigments with pure raw or refined linseed oil. 
 
 (c) Pastes in Japan.—The pastes in Japan shall be made by thoroughly 
 grinding the specified pigments in high-grade grinding japan. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) The mass color and character of the tint formed by mixture with 
 a white pigment shall be the same as, and the strength not less than, that of 
 a sample mutually agreed upon by buyer and seller. 
 
754 Yellow, Orange, Blue, and Green Pigments 
 
 (vb) The dry pigments shall meet the following requirements : 
 
 Total matter soluble in water, maximum, per cent...... < Saree 0.5 
 Total of all substances other than insoluble compounds of lead, 
 MAXIMUM, Per CONE. 6s. «obs. ao = w oie Wie eleneeen mene aie sc loge feat 
 Organic. colors of lakes. 62.6... 666 sess wine neler None 
 Coarse particles and skins (total residue retained on a No. 325 
 screen), maximum, per cent of the pigment.........5..... 
 
 (c) Paste in Oil—The pastes as received shall not be caked in the con- 
 tainer and shall break up readily in oil to form a smooth paint of brushing 
 consistency. They shall mix readily in all proportions without curdling, with 
 linseed oil, turpentine, or volatile mineral spirits, or any combination of these 
 substances. 
 
 The pastes shall meet the following requirements: 
 
 Pigment, minimam, per cent... ..... >. ssn vi vlads Skee ones {eeeto 
 Linseed oil, maximum, per cent... . 0% «ss. ose anemeeene dle w kone BU eee 
 Water and other volatile matter, ‘maximum, per CONT isa es eae 0.7 
 Coarse particles and skins (total residue retained on a No. 325 
 screen), maximum, per cent of the pigment................ 1.5 
 
 (d) Paste in Japan.—The pastes as received shall not be caked in the 
 container and shall break up readily in turpentine to form a smooth paint 
 of brushing consistency that will dry within one hour to a hard flat coat that 
 can be varnished within five hours of the time of application without streaking 
 or bleeding. They shall meet the following requirements : 
 
 Pigments, minimum, per cent......%. . 2. sss sels wie ets a eee 70 
 Vehicle (japan), maximum, per Cent. <2...) .05 066 eee ni Savard cau 
 Coarse particles and skins (total residue retained on a No. 325 
 screen), maximum, per cent of the pigment................. 1.5 
 Non-volatile matter in the vehicle, minimum, per cent of the 
 bc 00 CC) (: re rrr Sr sis aa epee eas ce 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload. one sample shall be taken at random from each carload. 
 
 A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
 PRUSSIAN BLUE 
 
 1. These specifications cover the pigment commonly known as Prussian 
 blue, Chinese blue, or iron blue. It may be purchased in the dry form, or 
 ground in oil or in japan to form a paste. 
 
 MANUFACTURE. 
 
 . (a) Dry Pigment.—The dry pigment shall be the blue product formed 
 by i reaction of solutions of iron salts with ferro or ferricyanide solution. 
 It shall not be admixed with any other substance. 
 
 (6) Paste in Oil—The paste in oil shall be made by thoroughly grinding 
 the specified pigment in raw or refined linseed oil. 
 
 (¢c) Paste in Japan.—The paste in japan shall be made by thoroughly 
 grinding the specified pigment in high-grade grinding japan. 
 
Yellow, Orange, Blue, and Green Pigments 755 
 
 PROPERTIES AND TESTS. 
 3. (@) The mass color and character of the tint formed by mixture with 
 a white pigment shall be the same as, and the strength not less than, that of a 
 sample mutually agreed upon by the buyer and seller. 
 (6) Dry Pigment.—The dry pigment shall conform to the following 
 requirements : 
 
 Total matter soluble in water, MAXHOUM Her cent. = Ase. ss oc. 0.5 
 Coarse particles (total residue retained on a No. 325 screen), 
 ee rns) i Cl a ee le 1.0 
 
 (c) Paste in Oil—The paste as received shall not be caked in the con- 
 tainer and shall break up readily in oil to form a smooth paint of brushing 
 consistency. It shall mix readily in all proportions, without curdling, with 
 linseed oil, turpentine or volatile mineral spirits, or any mixture of these 
 substances. The paste shall conform to the following requirements: 
 
 MAXIMUM MINIMUM 
 
 ME Ces bs chek See eee. ee eo: 48.0 
 Re OEP ICON ops. ws ccc cosine es odccncisccne. 52.0 ee 
 Moisture and other volatile matter, per cent........ 0.7 
 Coarse particles and skins (total residue retained on 
 
 Pa Croeo sereen), per Cent... 6... peso cece eee. 19 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the con- 
 fainer and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency, that will dry within one hour to a hard flat coat that 
 can be varnished within five hours of the time of application, without streak- 
 ing or bleeding. The paste shall conform to the following requirements : 
 
 MAXIMUM MINIMUM 
 
 MEO CT ECON Cs oo oooh vs cee cow nk ws eens pee. 48.0 
 Meetreew gana), per Cent... 2 ccd lec ceeccccecscn 52.0 ie 
 Coarse particles and skins (total residue retained on 
 
 Se Omoco SCreen) per Cent... . sss cele ccc eec acne ts ea 
 Non-volatile matter in the vehicle, per cent of the 
 
 Sh vai Ek Eis Se Cl cn a one 40.0 
 
 Note.—The physical properties and tests of Prussian blue, particularly 
 the tinting strength. are considered a better measure of value than the per- 
 centages of chemical constituents. 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or fraction thereof. If the packages are of such size that 1000 packages 
 amount to more than a carload, one sample shall be taken at random from 
 each carload. 
 
CHAPTER XLIII 
 ANALYSIS OF BLACK PIGMENTS 
 
 The black pigments include those which contain carbon as 
 their essential constituent. The introduction of asphaltic and 
 coal-tar mixtures complicates their chemical analysis. Min- 
 erals such as slate containing a substantial percentage of 
 carbon, natural and precipitated black oxides of iron are also 
 used to some extent in the industry. 
 
 The analysis of the simple black pigments may Be cog. 
 out in the following way: 
 
 Moisture.—Dry 2 grams at 105° C. for two hours. 
 
 Oil.— Extract 2 grams, with ether in a fat-extraction appa- 
 ratus. 
 
 Carbon.—Determine the carbon by difference after deter- 
 mining the moisture, oil and ash. For an exact determination 
 of carbon make a combustion test, absorbing the carbon 
 dioxide in soda-lime or caustic potash as usual. 
 
 The carbon in a paint pigment mixture may also be deter- 
 minded directly. The pigment is first extracted with a solvent. 
 
 It is then treated with hydrochloric acid and the mixture is — 
 
 boiled to decompose any carbonates present, such as lead 
 carbonate, calcium carbonate, etc. The contents of the beaker 
 are then evaporated to dryness and the free carbon deter- 
 mined by combustion. Another direct method of determining 
 carbon present with other pigments is now being studied in 
 this laboratory. It consists in floating the pigment in a 
 liquid, the density of which is slightly greater than that of a 
 carbon pigment. It is possible that this method may even 
 show a separation of lampblack which has a gravity of 1.8 and 
 graphite which has a specific gravity of 2.4. An analogous 
 method is already in use for mineralogical work and suitable 
 liquids for this purpose are described by John D. Sullivan in 
 Bureau of Mines Technical Paper No. 381. 
 
 Ash.—Ignite 2 grams to a bright red heat until all the car- 
 bon is driven off. If graphite is present, the ignition should be 
 carried out with the aid of oxygen. Should carbonate be pres- 
 ent, mix the ash with a small amount of ammonium carbonate 
 
 a 
 
Analysis of Black Pigments 757 
 
 and again ignite, thus reconverting to carbonate any oxide 
 which may have been formed. 
 
 Analysis of Ash.—The ash is boiled. with concentrated HC] 
 and the insoluble residue determined in the usual manner. The 
 
 filtrate is examined for calcium, magnesium and phosphorie 
 acid. 
 
 Calculate the magnesium to phosphate, any residual phos- 
 phoric acid to calcium phosphate and any residual calcium to 
 carbonate. In the case of graphite and black oxide of iron, 
 the analysis of the ash is carried out as with iron oxide pig- 
 ments in Chapter XLIV. 
 
 Gases.—Black pigments such as lamp or gas blacks may con- 
 fain as high as 15 per cent absorbed or adsorbed gases. High 
 vacuum is necessary to free such gases from the pigment. 
 
 A.S.T.M. STANDARD SPECIFICATIONS FOR LAMPBLACK 
 
 I. MANUFACTURE. 
 
 1. These specifications cover the pigment commonly known as lampblack. 
 The pigment may be purchased in the dry form, or ground in oil or in japan 
 to form a paste. 
 
 2. (@) The dry pigment shall be made by burning oils or tars in such a 
 manner as to form a deposit of carbon or soot. The pigment shall be high 
 grade in every respect, shall be free from oil, greasy matter and from admix- 
 ture of any other substance. 
 
 (b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
 the specified pigment with pure raw or refined linseed oil. 
 
 (¢c) Paste in Japan.—The paste in japan shall be made by thoroughly 
 grinding the specified pigment in high-grade grinding japan. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) The color and tone shall be equal to, and the tinting strength not 
 less than, that of a Sample mutually agreed on by buyer and seller. 
 
 (b) Dry Pigment.—The dry pigment shall meet the following require- 
 ments: 
 
 Coarse particles retained on a standard No. 325 screen, maxi- 
 
 I er So al are 5 cele poe ae ee Ging beens Gane cous 1.0 
 MEMEO Cr er Cents see Us Poe eek oe eo eee Lo 
 Benzol extract (which must be colorless), maximum. per cent.. 0.5 
 Tone when diluted with zine oxide............ --.-..Clear-blue-gray 
 
 (c) Paste in Oil.—The paste as received shall not be caked in the container 
 and shall break up readily in oil to form a smooth paint of brushing con- 
 Sistency. It shall mix readily in all proportions without curdling, with linseed 
 oil, turpentine, or volatile mineral spirits, or any combination of these sub- 
 stances. The paste shall meet the following requirements: 
 
758 Analysis of Black Pigments 
 
 MAXIMUM MINIMUM 
 
 Pigment, per Cent........-sescecececoresersenucens Pe 25 
 Linseed Oil, per CeNt... 20. 60. ee ce tee ses 5 5s 6 eis 75 
 Material volatile at 105° C......- 2. eee eee ree neeees 0.7 
 Coarse particles and skins left on a No. 325 screen 
 (per cent of the dry pigment) ....--++++++eeerees 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the con- 
 tainer and shall break up readily in turpentine to form a smooth paint of © 
 brushing consistency that will dry within one hour to a hard, flat coat. It 
 shall meet the following requirements: 
 
 MAXIMUM MINIMUM 
 
 Pigment, per cent... ..0....6+s0cs ee +0 neem seen : 25 
 Vehicle, per Cent. ..... 02 .csncensectcccsessecevesees 75 -s 
 Coarse particles and skins retained on a standard 
 
 No. 325 screen (per cent of the dry pigment)..... 1.0 
 Non-volatile matter in the vehicle, per cent of the 
 
 vehicle ccc eccas cece cee es @ + 6 viele nip eleeie Ste Meee 40 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
 ASTM. STANDARD SPECIFICATIONS FOR BONE BLACK 
 
 1. These specifications cover the pigment commonly known as bone black, 
 ivory black or drop black. It may be purchased in the dry form, or ground 
 in oil or in japan to form a paste. | 
 
 I. MANUFACTURE. 
 2. (a) Dry Pigment.—The dry pigment shall be made by the calcination 
 of bones and shall be unmixed with any other substance. 
 (b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
 the specified pigment in pure raw or refined linseed oil. 
 (c) Paste in Japan.—The paste in japan shall be made by thoroughly 
 grinding the pigment in high-grade grinding japan. 
 
 Il. PROPERTIES AND TESTS. 
 3. (a) The color and tone shall be equal to, and the tinting strength not 
 less than, that of a sample mutually agreed on by buyer and seller. 
 (b) Dry Pigment.—The dry pigment shall meet the following requirements : 
 
 Coarse particles retained on a standard No. 325 screen, maxi- 
 
 mum, per cent ..55.. TPP 2.0 
 Ash, maximum, per cent of pigment dried at 105° Gia 3 eee 88.0 
 Ash insoluble in acids, maximum, per cent........-+.+++++ee-s Pere 
 Benzol extract (which must be colorless), maximum, per cent.. 0.5 
 Tone when diluted with zine oxide..........+-+++++- Clear-blue-gray 
 
 (c) Paste in Oil.—The paste as received shall not be caked in the con- 
 tainer and shall break up readily in oil to form a smooth paint of brushing — 
 consistency. It shall mix readily in all proportions without curdling, with 
 linseed oil, turpentine, or volatile mineral spirits, or any combination of these — 
 substances. The paste shall meet the following requirements : 
 
Analysis of Black Pigments 759 
 
 MAXIMUM MINIMUM 
 EI EMCO Ge og eda cede vec. o. ee. eee 45 
 
 Coarse particles and skins (total residue retained on a 
 standard No. 325 screen, based on pigment), per 
 Ss oo Ss bare PERM lek. 2.5 
 
 (d) Paste in Japan.—The paste as received Shall not be caked in the con- 
 tainer and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency that will dry within one hour to a hard, flat coat. It 
 shall meet the following requirements : 
 
 MAXIMUM MINIMUM 
 (Se ENE BG So ee " 45 
 Beecren japan). per cent... 0... bee e ee oo ek 55 ar 
 
 OE oe Gace ne SSa a ha Pea 
 Non-volatile matter in the vehicle, per cent of the 
 ee ok koa Sy ooo cebcc ek: Sees 40 
 
 4. One sample shall be taken at random from each lot of 1000 packages or 
 less. If the packages are of such size that 1000 packages amount to more 
 than a carload, one sample shall be taken at random from each carload. 
 
CHAPTER XLIV 
 
 ANALYSIS OF IRON OXIDE PIGMENTS 
 (Yellow, Orange, Red and Blue) 
 
 The material originally published in previous editions of 4 
 
 this volume has been utilized in the drafting of A. S. T. M. 
 Specifications which are presented below. In addition to the 
 methods recommended for determination of the iron content, 
 reference might also be made to the use of a titanous chloride 
 solution for reduction purposes,* or to the use of the Jones’ 
 
 Reductor.t 
 
 A.S.T.M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
 YELLOW, ORANGE, RED, AND BROWN PIGMENTS 
 CONTAINING IRON AND MANGANESE 
 
 GENERAL METHODS. 
 
 SPECIFIC GRAVITY. 
 1. True specific gravity shall be determined in accordance with the 
 Standard Method of Test for Specific Gravity of Pigments (Serial Designation : 
 D 153) of the American Society for Testing Materials. 
 
 TINTING STRENGHT.# 
 
 2 The colors should always be compared with a carefully selected standard. 
 Weigh out accurately from 0.02 to 0.05 g. of color, place on a large glass 
 plate, add 12 drops of bleached linseed oil,§ and rub up with a flat-bottom 
 glass pestle or muller; then add 1 g. of pure ZnO, and grind with a circular 
 motion 50 times; gather up with a sharp-edge spatula and grind out twice 
 more in like manner, giving the pestle a uniform pressure. Next weigh out 
 a similar amount of the standard, and treat in exactly the same manner as 
 described above. Transfer portions of each paste to a microscope slide, quite 
 close together, and then draw a palette knife across both samples so as to make 
 them meet in a line (differences in tint are then easily seen). Compare the 
 tints as shown on both sides of the glass. The amount of pigment used will 
 
 vary with the tinting strength, but generally it suffices to take about 0.02 g. of © : 
 
 the reds and about 0.05 g. of the ochers. 
 
 * New Reduction Methods in Volumetric Analysis (1925). Cf. also Fox and @ 
 
 Bowles—Analysis of Pigments, Paints and Varnishes, p. 50 (1927). 
 
 +Scott, Volume I. 
 tHolley, “Analysis of Paint an Varnish Products,” 1912, p. 126. 
 
 §The use of “oxidized” oil should be avoided (oil that hsa become “fatty” $i 
 
 by standing around in a can or bottle). Poppy-oil could be used but it is 
 
 quite as necessary to have it reasonably fresh as when linseed oil is used. £ 
 
 In either case “stringy” pastes are not reliable. 
 
 q ki ae 
 *? wae 
 Bde eeu PL ey 
 
Iron Oxides: Yellow, Orange, Red,and Blue’ 761 
 
 If it is desired to express quantitatively the tinting strength of the pigment, 
 consider the standard pigment as having a tinting strength of 100, and then 
 vary the amount of the standard pigment until the tints are matched. 
 
 For example, let the amount of standard pigment for 100 strength test be 
 0.02 g. (=A). Vary this amount in units of 5 per cent, thus 0.019 or 0.021. 
 Let the amount taken to match a given strength — B, then 
 
 B 
 0 
 Tee 
 
 equals the tinting strength of the sample to be tested. 
 If the tone varies it may be difficult to make this measurement. | 
 
 ADDED COLORING MATTER. 
 
 3. Test the pigment successively with hot water, 95-per-cent ethyl alcohol, 
 alcoholic NaOH or KOH and acetic acid. Chloroform, NaOH, H,.SO,, HCl- 
 Stannous chloride, and other reagents may be tried." The presence of an 
 stannous chloride, an other reagents may be trie.* The presence of an 
 if desired.f 
 
 METHODS OF ANALYSIS OF INDIAN REDS, RED OXIDES 
 
 (PRINCE’S METALLIC, TUSCAN RED.) 
 LOSS AT 100° C. 
 
 4. Heat 2 g. in a steam-jacketed oven at atmospheric pressure for three 
 hours, or to constant weight. 
 
 LOSS ON IGNITION. 
 
 5. Ignite a portion in a covered porcelain crucible to constant weight. . 
 This may include combined water, CO,, organic matter, and some SO, if much 
 CaSO, is present. CO, may be determined on a separate portion of the sample 
 if desired.’ 
 
 FREE ACID OR ALKALI. 
 
 6. Boil 10 g. of sample with 100 cc. of water; filter and wash. Test filtrate 
 with litmus paper; if acid, titrate with standard alkali and methyl orange 
 and calculate to the equivalent of H,SO, If alkaline, titrate with acid and 
 calculate to the equivalent of Na,O. Test filtrate for alkali salts and alkaline 
 earths. 
 
 ADDED COLORING MATTER. 
 7. Tests as under “General Methods.” 
 
 INSOLUBLE, IRON OXIDE, ETC. 
 
 8. Digest 2.5 g. of the sample (previously roasted at a low temperature if 
 much organic matter is present; if very low in carbonaceous matter a little 
 KC1O:; or NaClO, may be used in effecting solution) with 25 ec. of HCl (adding 
 a little HNO, or chlorate, if not already added), wash off cover, and evaporate 
 to dryness. Take up with HCl and water, filter, wash with dilute HCl and 
 
 *Mor details consult Berr. “Tests for Coal-Tar Colors in Aniline Lakes.” 
 (English translation by C. Mayer) ; Schultz and Julius, “A Systematic Survey 
 of the Organic Coloring Matters;” Hall, “The Chemistry of Paints and Paint 
 Vehicles;:” and Mulliken, “Identification of Pure Organic Compounds,” Com- 
 mercial Dyestuffs, Vol. III. 
 
 7It is inadvisable to use platinum unless it is known that attacking sub- 
 stances are absent. 
 
762 Iron Oxides: Yellow, Orange, Red, and Blue 
 
 cold water. Make the filtrate up to 500 cc., mix, and examine as below.* 
 Ignite the residue and weigh as “insoluble matter’; if this contains BaSO, 
 it may be determined by fusing with six times its weight of Na,CO,, cooling, — 
 digesting with hot water, filtering, and washing the residue with hot water — 
 ‘until free of sulfate. * 
 
 Remove filtrate and place beaker used for the digestion underneath the — 
 funnel, pierce the filter with the glass rod, and wash the residue with a little ‘ 
 water into the beaker; then pour hot dilute HCl (1:1) over paper, and finally — 
 wash with hot water. If necessary add more HCl to the beaker to dissolve — 
 the BaCO,; heat to boiling, add dilute H,SO, in slight excess, let stand about ~ 
 one hour on steam bath; filter, wash, dry, ignite, and weigh BaSO, (This — 
 subtracted from total insoluble will give “insoluble silicious matter,” if it is i 
 desired to so report.) If it is desirable to analyze the insoluble silicious — 
 matter, this can be done by the usual methods for silicate analysis, but the 
 results should be reported as a separate analysis. 
 
 For the determination of iron place 100 cc. of the first filtrate in a flask, © 
 add about 3 g. of granulated zinc, put a funnel into the neck of the flask, heat — 
 when the action slackens; if basic salts separate out add a few drops of HCl. — 
 When the reduction is complete, add 30 ce. of H,SO, (1:2), and as soon as 
 the residual zinc is dissolved, wash down the funnel inside and out and the © 
 neck of the flask with a fine jet of water, filling the flask (1000 cc.) about 
 two-thirds full, cool in water, add 10 cc. of “titrating solution” (made by dis- 
 solving 160 g. of manganese sulfate in water, diluting to 1750 cc., adding 330 — 
 ce. of H,PO,, sp. gr. 1.72, and 320 cc. of concentrated H,SO,), and titrate with © 
 KMnO, (5.659 g. per liter) that has been standardized against Bureau of © 
 Standards sodium oxalate. Run a blank on the zinc, correct for same and — 
 calculate total iron as Fe.O,. Instead of adding the zine to the solution, — 
 the reduction may be effected in a zine reductor.¢ ; 
 
 The Fe,O, may also be determined by the K.Cr,0, method.§ 
 
 LIME. 
 
 9. Dilute an aliquot of 100 cc. of the original solution to about 200 ce., add — 
 10 ce. of HCl, make alkaline with NH4,OH, add 2 or 8 cc. of bromine water. 
 and boil till excess of NH» is expelled. Let settle, wash by decantation, — 
 redissolve in HCl, and reprecipitate with NH,OH and bromine water, (Pre- — 
 cipitate — Fe,O,.Al,0,.T10,.P,0..MnO,.) This precipitate may be ignited ® 
 and weighed if desired. § 
 
 To the combined filtrates add a few drops of NH4,OH, heat to boiling, and © 
 add an excess of saturated ammonium-oxalate solution; continue the boiling 
 until the precipitate becomes granular, let stand about 30 minutes, filter, and — 
 wash with hot water till free of ammonium oxalate;|| place beaker in which — 
 precipitation was made under the funnel, pierce apex of filter with stirring — 
 
 *For more exact work this filtrate should be evaporated to dryness and ; 
 SiO, removed. 
 
 *If the insoluble contains appreciable amounts of Fe it will be necessary 
 to fuse it with Na,CO, or K,S,O, to determine total Fe in samples. 
 tLord and Demorest, “Metallurgical Analysis.” 19138, pp. 28-29. 
 §/bid., pp. 21-26. ; 
 é 
 |For more exact work this precipitate should be dissolved in HC] and the 
 calcium oxalate reprecipitated as above. 
 
 a I 
 
Iron Oxides: Yellow, Orange, Red,and Blue’ 763 
 
 rod and wash precipitate into beaker with hot water, pour warm dilute 
 H.SO, (1:4) through paper and wash a few times; add about 30 ce. of 
 H,SO,4 (1:4), dilute to about 250 cc., heat to 90° C. and titrate at once with 
 standard KMnO, solution (solution should not be below 60° C. when end-point 
 is reached). Calculate to CaO. (The Fe value of KMnO,X0.502—CaO.) The 
 calcium-oxalate precipitate may be ignited to constant weight as CaO. If 
 desired, magnesia may be determined as Mg P.O, in the usual manner in 
 the filtrate from the calcium oxalate.* 
 
 SOLUBLE SULFATES. 
 
 10. Treat 1 g.¢ of the pigment (roasted gently if much organic matter is 
 present) with 30 ce. of HCl, boil 10 minutes, add about 50 cc. of water, boil, 
 filter, and wash with hot water. Heat the solution to boiling, add NH,OH, 
 filter and wash a few times with hot water; dissolve precipitate in hot dilute 
 HCl and reprecipitate with NH,OH, wash well with hot water. Render united 
 filtrates just distinctly acid with HCl, boil, add by drops with stirring excess 
 of 10-per-cent BaCl, solution, boil about 10 minutes, filter on a Gooch crucible, 
 wash with hot water, ignite and weigh as BaSOy. Calculate to SO3 or CaSQx,. 
 
 TOTAL SULFUR OTHER THAN THAT PRESENT AS BaSQy,. 
 
 11. Treat 5 g. of the sample in a covered porcelain dish with 50 ce. of aqua 
 regia ( 1 HNO,:9 HCl) and evaporate to dryness on steam bath. Add 20 ce. 
 of concentrated HCl and about 250 cc. of water, make double NH4,0H precipi- 
 tation; determine BaSO, as given under “Soluble Sulfates.” 
 
 METHODS OF ANALYSIS OF OCHERS 
 
 12. Loss at 100° C., loss on ignition, insoluble matter, total or soluble iron, 
 alumina, lime and sulfur may be determined as outlined under the “Methods 
 for Analysis of Indian Reds, etc.,’’ using 1 g. or an aliquot corresponding to 
 this weight. 
 
 TINTING STRENGTH. 
 
 13. Test as under ‘General Methods.” Tests should be made for solubility 
 in water, and reaction to litmus paper. 
 
 LEAD CHROMATE. 
 
 14. If present, the lead is removed in the above scheme by nearly neutral- 
 izing the filtrate from the insoluble matter with NH,OH, cooling, and passing 
 in H.S, to precipitate PbS. Filter, wash with water containing H2S, dissolve 
 PbS in hot dilute HNOs, add 10 cc. of concentrated H2SO4, evaporate till SOg 
 is evolved, cooi, dilute to 200 cc., let stand a few hours, filter on a Gooch 
 crucible, wash with 1-per-cent H»SO,4, ignite, and weigh PbSO,4. Calculate to 
 PbO or Pb. Heat the filtrate from the PbS to expel HoS, oxidize with a little 
 HNOs, and make up to volume if working on more than 1 g. 
 
 *Tf desired, a direct determination of Al O, may be made on an aliquot of 
 the solution or on the HCl solution of the NH:OH precipitate by Peters’ phos- 
 phate method (this will include titanic acid) as described by Blair. “The 
 Chemical Analysis of Iron,” and Philips, ‘‘“Methods of Iron Analysis Used in 
 the Pittsburgh District.” 
 
 +If low in soluble sulfates use a larger portion of sample. 
 
764 Iron Oxides: Yellow, Orange, Red, and Blue 
 
 The iron is best determined in an aliquot by the K>Cr,07 method. Another” 
 aliquot is treated with NH,OH, the precipitate containing Alj.O3. Fe 03.Cr203. 
 P,0;5.TiOg. Lime and MgO may be determined in filtrate. . 
 
 The NH,OH precipitate is dissolved in hot dilute HCl, washing paper with ; 
 hot water, cooled, oxidized with Na,O, boiled to expel H,O ,, cooled, cover et 
 glass washed off, diluted to about 150 cc., and acidified with H,SO4. Add a i 
 measured excess of ferrous ammonium-sulfate solution— (NH4)2Fe(SO4)9. — 
 6H,O, 12.4 g.; concentrated H,SO,, 50 ce.; and water to make 1 liter, and b 
 titrate back with standard KyCr,O, solution, using K3;Fe(CN)¢ solution as an ~ 
 outside indicator. The (NH4) .Fe(SO4)2.6H.O solution is titrated with the — 
 K,Cr.07 solution to determine its value in terms of the latter. The Fe value ) 
 of the K,Cr,0, solutionX0.597=CrO3. : 
 
 Or, moisten 1 g. of the pigment with water, add 5 ce. of concentrated HCl, 
 boil a few minutes, cool, add Na ,O, in excess, boil to expel HO02, cool, wash ~ 
 off cover glass, dilute, acidify with H S04, and titrate CrOg as above. 
 
 VENETIAN RED. F 
 
 15. Analyze as given ‘under “Methods for Analysis of Indian Reds, etc.” 
 Insoluble matter may be treated with HF and H»S0O,4 to determine SiO, by ~ 
 loss if desired. ‘ 
 
 METHODS OF ANALYSIS OF SIENNAS AND UMBERS., 
 16. After gently roasting to destroy organic matter, test as given under 
 “Methods for Analysis of Indian Reds, etc,” 
 
 MANGANESE. : 
 17. Manganese is determined by the bismuthate method.* Ignite gently ~ 
 (to destroy organic matter) 1 g. of the sample in a platinum dish, cool, add 
 10 ce. of water 4 ce. of concentrated H,SO, and about 20 ce. of HF (if neces- 3 
 sary, add a little sulfurous acid). Evaporate until the Hj,SO, fumes freely, — 
 cool and dissolve in 25 cc. of HNOg (1 part concentrated HNO, to 3 parts © 
 water). If no appreciable residue remains, transfer to a 100-cc. volumetric 
 flask, using 25 ce. of HNOg (1:3) to rinse the dish, dilute to the mark with © 
 water, mix thoroughly. If there is an appreciable residue, filter on a small ; 
 filter, wash with water, ignite residue in a platinum crucible, and fuse with © 
 a little sodium or potassium pyrosulfate. Dissolve in water, with the addition ~ 
 of a little HNOs, add to the main filtrate, evaporate nearly to dryness, take up — 
 in HNO, (1:3) and transfer to the flask as before. Pipette an aliquot of 10 ; 
 ce. into a 200-cc. Erlenmeyer flask, add 30 ce. of water and 10 ce. of concentrated — 
 HNO,, sp. gr. 14; add about 0.5 g. of sodium bismuthate, heat for a few 
 minutes, or until the pink color has disappeared with or without the precipita- 
 tion of MnO»,. Add a few small crystals of sodium or potassium nitrite to 
 dissolve the MnO, and boil the solution several minutes to expel nitrous 
 fumes (a little NasCOz, will aid this). Add water to bring the volume up to 
 50 ec. and cool to about 15° C.; add about 0.5 g. of bismuthate and shake the — 
 flask well. Add 50 ce. of water containing 30 ce. of concentrated HNO: to the 
 liter, filter by suction through an asbestos felt into a 300-cc. Erlenmeyer flask — 
 and wash with 50 to 100 cc. of the same acid. Run in a measured volume of — 
 standard ferrous ammonium-sulfate solution and titrate to a faint pink color _ 
 
 *Blair, “The Chemical Analysis of Iron.” 
 
Iron Oxides: Yellow, Orange, Red,and Blue 765 
 
 with standard KMnO, solution. The number of cubic centimeters of the KMnO, 
 solution obtained, subtracted from the number corresponding to the volume 
 of ferrous solution used, will give the volume of KMnO, equivalent to the 
 manganese in the sample, which, multiplied by the value of the KMnO, in 
 Mn, gives the weight of manganese in the portion of sample used. 
 
 Standard KMnO, Solution.—The solution of KMnO, is composed of 1 g. 
 dissolved in a liter of water. The Fe value of this solution « 0.197 = Mn 
 This solution may be standardized against Bureau of Standards sodium 
 oxalate (using about 0.05 to 0.1 g.).* Weight of Na.C.O, * 0.197)—= Mn 
 Twelve grams of (NH4)oFe(SO,4)5.6H».O, 25 ce. of concentrated H2.SO,4, and 
 25 ce. of HgPO4, sp. gr. about 1.7, are made up to 1 liter with water. The 
 value of this solution should be determined against the KMnQO, each day as 
 follows: 
 
 Measure into a 200-cc. Erlenmeyer flask 50 cc. of HNO; (1:3), cool, add a 
 little bismuthate, dilute with 50 cc. of 3-per-cent HNOs, filter by suction 
 through an asbestos felt into a 300-cc. Erlenmeyer flask, and wash with 50 cc. 
 of 3-per-cent HNOs. Run in 25 cc. of the ferrous solution and titrate with 
 KMnOy, solution. Instead of titrating the permanganie acid formed by the 
 bismuthate with the ferrous solution and then titrating back with KMn0O,, 
 a direct titration with standard sodium arsenite solution may be made.t 
 
 A.'S.T.M. TENTATIVE SPECIFICATIONS FOR MINERAL IRON OXIDE. 
 1. These specifications cover iron oxide and iron hydroxide pigments of 
 mineral origin and of red and brown colors. 
 
 I. MANUFACTURE. 
 
 2. (a) Dry Pigment.—The pigment shall be very finely ground iron oxide 
 or iron hydroxide or a mixture thereof. Siliceous minerals may be present 
 and, if necessary, sufficient carbon pigment may be added to produce the 
 desired color. 
 
 (b) Paste——The paste shall be made by thoroughly grinding the specified 
 pigment with pure raw or refined linseed oil. 
 
 II. PROPERTIES AND TESTS. 
 3. (a) The mass color and character of the tint formed by mixture with a 
 _white pigment shall be the same as, and the strength not less than, that of a 
 sample mutually agreed upon by buyer and seller. 
 (b) Dry Pigment.—The pigment shall conform to the following require- 
 ments: 
 MAXIMUM MINIMUM 
 
 MCPOMICG POP CONG. .cacice ccc secs etuwecesevepas its 30.0 
 Material other than ferric oxide, insoluble siliceous 
 
 matter and loss on ignition, per cent............. 10.0 
 Coarse particles retained on a Standard No. 325 
 
 MRP EPEC ONIN re p59. nice cas ab ote pe ite ha wees a's, « bese 3.0 
 
 Organie coloring matters shall be absent. 
 
 The color and color strength, when specified, and the drying time with a 
 vehicle which has been mutually agreed on, shall be equal to those of an 
 agreed sample. 
 
 *W. Blum, “Original Communications,” Eighth International Congress of 
 Applied Chemistry, Vol. I, pp. 61-85. 
 *Lord and Demorest, “Metallurgical Analysis,” 1913, p. 82. 
 
766 Iron Oxides: Yellow, Orange, Red, and Blue 
 
 (c) Paste-——The paste as received and three months thereafter shall not 
 
 be caked in the container and shall break up readily in linseed oil to an 
 a smooth paint of brushing consistency. It shall mix readily with linseed oil, | 
 
 turpentine or volatile mineral spirits, or any combina of these, without 
 curdling. 
 The paste shall conform to the following requirements: 
 MAXIMUM MINIMUM 
 
 Pigment, per’ Cent... ...se<s's5 v0 9 seers mee ear 72.0 68.0 4 
 Linseed oil, per Cent... 26. o< 206 ewes yo eee eee 32.0 28.0 
 Moisture and other volatile matter, per cent......... 0.7 Ease 
 
 Coarse particles and skins (total residue retained on 
 a Standard No. 325 sereen, based on pigment), 
 POP CONG. . ev sewn ae cee cele eee om oe beeen 3.5 cise 
 
 4. One sample shall be taken at random from each lot of 1000 packages | 
 
 or less. If the packages are of such size that 1000 packages amount to more 
 
 than a carload, one sample shall be taken at random from each carload. 
 
 A.S.T.M. STANDARD SPECIFICATIONS FOR OCHER. 
 
 1. These specifications cover ferrous earthy pigments, included under the— 
 general term “Ocher” and purchased either as dry pigment or ground in oil | 
 
 or in japan to form a paste. 
 
 MANUFACTURE. 
 2. (a) Dry Pigment.—The pigment shall be a hydrated oxide of iron, 
 permeating a siliceous base, and shall be free from added impurities and added 
 coloring matter. 
 
 ere 
 
 (b) Pastes in Oil—The aste shall be made by thoroughly grinding thal 
 
 specified pigment in pure raw or refined linseed oil. 
 (c) Pastes in Japan.—The paste shall be made by thoroughly grinding the 
 specified pigment in high-grade grinding japan. 
 
 PROPERTIES AND TESTS. 
 
 3. (a) The mass color and character of the tint formed by mixture with a 
 
 white pigment shall be the same as, and the strength shall not be less than, 
 
 that of a sample mutually agreed upon by the buyer and seller. 
 
 ments: 
 MAXIMUM MINIMUM 
 Coarse particles retained on a No. 325 screen, per cent 1.0 
 
 Iron oxide (Fe O03), per cent. ..4 5.5.00 se ee pan ieee syste 17 
 Lime CaO), per cent. vec. s J. « sicuwie sie ene PR 5 45 
 Lead, chromate, per CONC. 2.25. 02s dss «anit oe pee None 
 Orgahie colors, pet C@Dt...: 04s 0's «ss 0 so Gis eee None 
 
 (c) Paste-——The paste as received shall not be caked in the container and | 
 
 shall break up readily in oil to form a smooth paint of brushing consistency. 
 
 (b) Dry Pigment.—The pigment shall conform to the following requilaay 
 
 It shall mix readily in all proportions, without curdling, with linseed oil, 
 turpentine or volatile mineral spirits, or any mixture of these substances. 
 
 The paste shall conform to the following requirements : 
 MAXIMUM MINIMUM 
 
 Pigment, per Cent. ..o05 005.5 0s le 0 aca) cee 73 69 
 Linseed ofl, per Cent... .s4 06. «ac 5 0 slew sen 31 27 
 Moisture and volatile matter, per cent............... 0.5 se 
 
 Coarse particles and skins (total residue retained on a 
 Standard No. 325 screen, based on pigment), per 
 COTE. 05.00 va: 0 nee 80 evo wane bdo wets om Fea, eee 
 
Gold Bronze, Aluminum Bronze 767 
 
 (d) Paste in Japan.—The paste as received shall not be caked in the con- 
 fainer and shall break up readily in turpentine to form a smooth paint of 
 brushing consistency that will dry within one hour to a hard, flat coat that 
 can be varnished within five hours of the time of application, without streaking 
 or bleeding. The paste shall conform to the following requirements: 
 
 MAXIMUM MINIMUM 
 
 ITO T HCCI ON 6. GS. oo ls cc ceo ca cc ee ce acces Ts 69 
 Peer C aT) ADET CONG. 6 ek cede ccc coe ce can weve 31 at 
 
 Coarse particles and skins (total residue retained on a 
 
 Standard No, 325 screen, based on pigment), per 
 
 ee se eh os oe vs beck 6 esc acd bcleloee bles 1.5 Ne 
 Non-volatile matter in vehicle, per cent of the vehicle .... 40 
 
 4. One sample shall be taken at random from each lot of 1000 packages 
 or fraction thereof. If the packages are of such size that 1000 packages 
 amount to more than a carload, one sample shall be taken at random from 
 each carload. 
 
 A. 8. T. M. TENTATIVE SPECIFICATIONS FOR GOLD 
 BRONZE POWDER 
 1, These specifications cover the materials commonly known as gold bronze, 
 pale gold bronze, and rich gold bronze powders. 
 
 PROPERTIES AND TESTS 
 
 2. (a) The gold bronze powder shall be suitable for making gold bronze 
 paint. It shall match in shade and fineness a sample mutually agreed upon 
 by the buyer and seller. 
 
 ()) It shall be made from new ingot metals and the finished powder shall 
 consist essentially of copper and zine. It shall consist of fine polished flakes 
 with not to exceed 3 per cent of fatty or oily matter (polishing lubricant) to 
 give good “leafing” properties. 
 
 (c) It shall “leaf” readily with spar varnish and ordinary bronzing liquids, 
 and when mixed in the proportion of 314 to 4 lbs. to a gallon, shall give a free 
 flowing, smooth, continuous coating. 
 
 (d@) A residue of not more than 0.1 per cent shall be retained on a No. 
 100 sieve. 
 
 8. One sample shall be taken at random from each lot of 1000 packages 
 or fraction thereof for purpose of test. 
 
 A. S. T. M. TENTATIVE SPECIFICATIONS FOR ALUMINUM 
 POWDER FOR PAINTS 
 
 1. These specifications cover the material produced by a stamping process 
 and commonly known as “aluminum bronze powder.” The product produced 
 by a spraying operation, which consists of more or less nearly spherical par- 
 ticles, and is sometimes known in the trade as “aluminum powder,” is not 
 covered by these specifications. 
 
 PROPERTIES AND TESTS 
 
 2. (a) The aluminum powder shall be suitable for making aluminum paint. 
 
 It shall match in luster and fineness a sample mutually agreed upon by the 
 buyer and seller. 
 
‘ND 
 
 b> 
 
 768 A. 8S. T.M. Standard Definitions 
 eee 
 
 (bo) It shall contain no filler or adulterant, such as mica, and shall be 
 commercially pure aluminum in the form of fine, polished flakes with not to 
 exceed 3 per cent of fatty or oily matter (polishing lubricant). 
 
 (c) It shall have good “leafing’” properties (by ‘Jeafing” is understood 
 the property of forming an apparently continuous brilliant film over the entire 
 free surface of a mixture of the powder in spar varnish within one minute 
 after cessation of stirring the mixture). 
 
 (d) A residue of not more than 0.2 per cent shall be retained on a No. 100 
 sieve when the powder is washed through with alcohol. It shall “leaf” readily 
 with spar ‘varnish,* and when mixed with such varnish in the proportion 
 of 2 lbs. to the gallon shall give a free flowing, smooth, continuous coating. 
 
 3. One sample shall be taken at random from each lot of 1000 packages or 
 fraction thereof for purpose of test. 
 
 EEE EE EEEEEEEEED 
 
 A. 8. T. M. STANDARD DEFINITIONS OF TERMS USED IN 
 PAINT SPECIFICATIONS 
 
 Standard.—Materials, methods, qualities, properties, etc., set forth by speci- 
 fication as a basis for the measurement of requirements. 
 Equal To.—The use of this term should be avoided if possible. 
 
 The avoidance of this term is recommended wherever possible because 
 the specifications themselves should state ‘the qualities, ete. desired. In 
 specifications having the sanction of the American Society for Testing 
 Materials, it is to be assumed that this feature will be developed to its fullest 
 extent. 
 
 Pure.—Free from admixture of any foreign substance. 
 Commercially Pure—The use of this term should be avoided if possible. 
 
 The avoidance of this term is recommended wherever possible because it 
 involves the acceptance of standards likely to cause dispute, whereas speci- 
 fications having the sanction of the American Society for Testing Materials 
 should involve the establishment of their own standards. 
 
 Adulteration.—The partial substitution of one substance for another without 
 acknowledgement. 
 
 The addition of the words “without acknowledgment” makes this defini- 
 tion clear. Substitution with acknowledgment involves no improper motive. 
 If it is done without acknowledgment an improper motive may be assumed. 
 Adulterant.—A substance substituted partially for another without acknowl- 
 
 edgment. 
 Opacity—The degree of obstruction to the transmission of visible light. 
 
 In this sense “opacity” is a relative term, it being considered that given 
 a film sufliciently thin, in paint technology at least, there is no absolutely 
 opaque substance. 
 
 Covering Power.—The use of this term should be avoided if possible. 
 
 This term has been used so loosely that it might mean hiding power, 
 spreading power, or the simple property of producing a coat. 
 
 Hiding Power.—The power of a paint or paint material as used to obscure 
 a surface painted with it. 
 
 In this definition the word “obscure” means to render invisible or to 
 
 cover up a surface so that it cannot be seen. 
 
 * Federal Specifications Board Specification No. 18, Varnish, Spar, Water- 
 Resisting. oy 
 
 ay, 
 oy 
 
A.S. T. M. Standard Definitions 769 
 a ee ba al ae rear: Seale ate nn Ret bd 
 
 Spreading Rate.—The rate at which a paint or paint material, as used, is 
 brushed out to a continuous uniform film expressed in terms of the area 
 to which a unit volume, as used, is applied. 
 
 This term must not be confused with the much-abused term “spreading 
 power.” The use of the term “spreading rate” is illustrated in the following 
 sentence: “The paint when spread on a planished iron surface at the rate 
 of 600 sq. ft. to the gallon will not sag or run when placed in a vertical 
 position at 70° F.” 
 
 Fineness.—The extent of sub-division of a substance as indicated under 
 definite prescribed conditions. 
 
 Orystallin— Having a definite structure referrable to one of the erystallo- 
 graphic systems. 
 
 According to definition a material is not crystallin if it has not a crys- 
 tallin form irrespective of the optical and other properties it may possess. 
 
 Amorphous.—Without regular or definite form. 
 
 This definition as given here has a broader meaning than it possesses 
 when it is used in mineralogical writings. Protozoa, if of definite form, are 
 not amorphous and may not be crystallin. 
 
 Paint——A mixture of pigment with vehicle, intended to be spread in thin 
 coats for decoration. or protection, or both. 
 
 According to this definition a mixture of pigment and varnish is a paint, 
 and on the other hand a solution of stains in oil or varnish, no pigment being 
 present, is not a paint. 
 
 Size—In the painting art, a liquid coating material, intended to close the 
 pores, used to prepare a surface for further treatment. 
 It is not regarded as a finishing material 
 
 Varnish.—A liquid coating material, containing no pigment, which flows out 
 to a smooth coat when applied and dries to a smooth, glossy, relatively 
 hard, permanent solid when exposed in a thin film to the air. 
 
 Some materials possessing the other characteristics dry without the usual 
 gloss and are termed “flat varnish.” 
 
 Enamel.—A special kind of paint which flows out to a smooth coat when 
 applied and dries to a smooth, glossy, relatively hard, permanent solid 
 when exposed in a thin film to the air. An enamel always contains pig- 
 ment and has considerable hiding power and color. Some enamels dry 
 to a flat or eggshell finish instead of a gloss finish. 
 
 Filler—A special kind of paint used for filling pores or other small breaks 
 in the continuity of a surface to render it smooth preparatory to further 
 treatment. When applied and exposed to the air, a filler should dry to a 
 relatively hard, permanent solid capable of properly supporting subse- 
 quent coats. 
 
 Pigment.—The fine solid particles used in the preparation of paint, and sub- 
 stantially insoluble in the vehicle. 
 Asphaltic materials are not pigments except when they contain substances 
 
 substantially insoluble in the vehicle in which they are used. 
 
 Toner.—An organic pigment which does not contain inorganic pigment or 
 inorganic carrying base. 
 
 _ Lake—A special type of pigment consisting essentially of an organic soluble 
 
 coloring matter combined more or less definitely with an inorganic base 
 
770 A. S. T. M. Standard Definitions : 
 
 or carrier. It is characterized generally by a bright color and a more é 
 or less pronounced translucency when made into an oil paint. 
 
 Under this term are included two (and perhaps three) types of pigment: 
 (a) the older original type composed of hydrate of alumina dyed with a 
 solution of the natural organic color, (b) the more modern and far more 
 extensive type made by precipitating from solution various coal-tar colors — 
 by means of a metallic salt, tannin, or other suitable reagent, upon a base ~ 
 or carrier either previously prepared or coincidently formed, and (¢) a num- — 
 ber combining both types in varying degree, might be regarded as a third class. 
 Vehicle—The liquid portion of a paint. 
 
 Here anything that is dissolved in the liquid portion of a paint is a part 
 of the vehicle. 
 Volatile Thinner.—All that liquid portion of a paint, water excepted, which — 
 
 is volatile in a current of steam at atmospheric pressure. ; 
 Non-Volatile Vehicle-—The liquid portion of a paint excepting its volatile 
 thinner and water. 
 Drying Oil.—An oil which possesses to a marked degree the property of@ 
 readily taking up oxygen from the air and changing to a relatively hard, 
 tough, elastic substance when exposed in a thin film to the air. 
 Semi-Drying Oil.—An oil which possesses the characteristics of a drying oil 
 but to a less degree. 
 
 There is no definite line of demarcation between drying and semi-dryingg & 
 oils. 
 Non-Drying Oil.—An oil which does not of itself possess to a perceptiblaam 
 
 degree the power to take up oxygen from the air and lose its liquid — 
 characteristics. 3 
 Tinting Strength—The power of coloring a given quantity of paint or pigment — ¥ 
 selected as a medium standard for estimating such power. : 
 Color—A generic term referring inclusively to all of the colors of the spec-_ : 
 trum, white and black, and all tints, shades and hues which may be 
 produced by their admixture. 4 
 
 Color involves a definite effect produced by the action of light upon the | 
 retina of the eye dependent upon the optical composition of the light. This 
 term is also used in reference to material substances such as pigments, stains, 
 dyes, ete., but in specifications it should be recognized that color is primarily 
 a physiological sensation, 
 
 By ee 
 
 Tint.—A color produced by the admixture of a coloring material, not white, 
 with a white pigment or paint, the white predominating. £ 
 Shade-—A term descriptive of that difference between colors which results K 
 from a difference in luminosity only, the other color constants being 
 essentially equal. A darker shade of a color is one that has a lowe 
 luminosity. | 
 Primarily the term “shade” is akin to shadow designating darkness or 
 reduced illumination, and therefore when strictly used should eXpress only 
 such change as depends on reduced luminosity ; it has been defined by several - 
 authorities as the mixture of black with a color, thus establishing its opposite 
 character to “tint,” but by extension of its relative sense it has been fre- 
 quently and widely used to include lighter shades by use of the adjective 
 “lighter” or “paler.” Although such expressions apparently involve a contra-— 
 diction, it is clear that while we may have a shade of color or darker color 
 
 of the same sort, it is easy to conceive of another shade not quite so dark and 
 therefore lighter. 
 
 Hue.—The predominating spectral color in a color mixture. 
 Tone.—The color which principally modifies a hue or a white or a black. 
 
 aD 
 
A.S. T. M. Standard Definitions id 
 ne SS a 
 
 Drying.—The solidification of a film. 
 
 Drier.—A material containing metallic compounds added to paints and paint- 
 ing materials for the purpose of accelerating drying. 
 
 Specific Gravity——The ratio of the weight of a unit volume of a substance to 
 the weight of an equal volume of water at defined temperatures. 
 
 Density.—The use of this term should be avoided if possible. 
 
 Density is a scientific term meaning the mass of a unit volume. Its 
 numerical expression will vary with the units selected, and there is no ocea- 
 
 . 
 
 sion for using it when the term “specific gravity” is defined. Confusion may 
 
 be avoided by not using the word “density” in specifications, 
 
 Gallon.—The measured gallon is 231 cu. in. Where a measured gallon is 
 called for, the temperature at which it is to be measured should be 
 specified. Where a gallon of definite weight is called for, the weight 
 should be specified or obtained from the specific gravity of the material 
 at a definite temperature. 
 
 This is the standard United States gallon. 
 
 Water.—Dissolved water or water not definitely or chemically combined. 
 
 Dry.—In paint materials: containing no uncombined water. In paint films: 
 completely solidified. 
 
we 
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Abrasion resistance............. 
 Accelerated method of testing 
 
 painted cement surfaces...... 
 Accelerated tank for cement test- 
 
 ing 
 Accelerated testing cabinets .... 
 Accelerated tests on galvanized 
 
 pipe 
 Accelerated tests on- metals.... 
 Acidity of oil affecting lithopone 
 Acid number of varnish........ 
 Acid value of varnishes........ 
 Air bubble viscometer.......... 
 Merlin tension............... 
 
 eeeeoeree ese ee eeer eee eeee ee 0 @ 
 
 eoeceee eee eeees ee eee eee eee eo 
 
 Airplane dopes, Durability of .399, 
 
 Airplane dopes, Durability tests 
 Airplane fabric, Durability of. es 
 Alkali increase test for tung oil 
 
 varnishes 
 
 Aluminum alloys, Paint tests 
 pS el Are eel ie a 
 Aluminum powder, A.S.T.M. ten- 
 tative specifications for....... 
 Aluminum primers for wood.... 
 Aluminum stearate gel.......... 
 
 Aluminum stearate, Jelly test.... 
 Aluminum stearate, Specifications 
 for 
 Aluminum stearate, Testing of. 
 Analysis and _ specifications for 
 ME PCOOUINE Coe ics et eee es 
 Analysis of lacquer, 
 for 
 Analysis of mixed driers...... 
 mapivsis Of paint olls.......... 
 Beer yeas OF PAINS. . 06.06. .e e ees 
 Analysis of pyroxylin coatings.. 
 Merriseot SHeMAC...3......5.- 
 Meiveis sol Vvarnish............ 
 Analysis of varnish resins...... 
 PeerOUMNNe PAINtS.......0....6. 
 Apparatus for testing tung oil.. 
 
 Apparent density of pigments.... 
 meeem nbrasion test............ 
 Ash in varnish...... Seb oe Ree 
 A. S. T. M. cooperative work on 
 Mexapromide test............. 
 A. 8. T. M. method for reporting 
 0 | 
 A. S. T. M. method of examina- 
 tion of lacquer pigments...... 
 A. 8. T. M. proposed methods for 
 testing lacquer enamels...... 
 A. S. T. M. recommended tenta- 
 
 _ tive specification for soluble 
 nitrocellulose 
 
 447 
 
 424 
 bo4 
 
 A. S. T. M. specifications for 
 COATSEG PATHICles ois se Gees w cece 
 A. S. T. M. standard method for 
 BPOCIIC= STA VIE Mee Sons area a kw whens 
 A. S. T. M. standard method for 
 testing oleo-resinous varnishes 
 A. S. T. M. standard method of 
 test for flash point of volatile 
 flammable» liquids... 232.94... 
 A. S. T. M. standard methods for 
 COSTING SGM Be eels ees eee 
 A. S. T. M. tentative specifications 
 Sampling and testing turpen- 
 tine 
 A. 8S. T. M. standard specification 
 LOT? Orange -SHEHACY co 44s Wks 6. 
 A. S. T. M. standard specification 
 for perilla oil, raw or refined 
 A. S. T. M. tentative method for 
 determination of wax in shellac 
 A. 8. T. M. tentative method of 
 test for elasticity or toughness 
 of varnishes by addition of lin- 
 BCU SOL othe se Gost aie See 
 A. 8. T. M. tentative method for 
 testing insulating varnish..... 
 A. S. T. M. tentative methods of 
 sampling and testing’ lacquer 
 solvents and diluents......... 
 A. S. T. M. tentative methods of 
 testing shellac varnish........ 
 A. S. T. M. tentative specification 
 for boiled linseed oil......... 
 A. 8. T. M. tentative specification 
 for petroleum spirits (mineral 
 
 eoeeee ere eee eee ese eeeee eee 
 
 SDLCILS hare ee ata ea ays 
 A. 8. T. M. tentative specification 
 for raw linseed oil............ 
 
 A. 8. T. M. tentative specification 
 LOVTRW CON SEOs soe ee alectale wie t's 
 A. S. T. M. tentative specification 
 for soya bean oil, raw or re- 
 fined 
 
 oe eee eee ee eee www eee ee ee 
 
 592 
 
 A. 8S. T. M. tentative specifications — 
 
 for destructively distilled wood 
 turpentine 
 A. S. T. M. standard specifications 
 for gum spirits of turpentine 
 and steam distilled wood tur- 
 pentine 
 Atlantic City exposure tests.... 
 Atlas accelerated testing cabinet 
 Automobile black baking enamels, 
 Testing 
 Automobile black baking japans 
 Average specific gravity data.... 
 
 Cr 
 
 oe eer eee eee eee eee ee ee wo ow 
 
 eoeoerreree eee ee eee ee ee eee 
 
 369 
 322 
 
 548 
 537 
 144 
 
774 
 
 Index 
 
 Bailey’s hexabromide test on oils 420 
 
 Baking ‘japans; Black vawvs esa. 537 
 Barton’s method for tinting 
 SUYONSET i SS is eae ee eres hs 303 
 Basic carbonate white lead..... 697 
 3asic sulphate white lead...... 698 
 Bawtree colorimeter............ 229 
 Bending tests on lacquers...... 618 
 Beta-elaeostearin, Accelerators 
 FOR proaguchie <6 ss. Bei een ate 45 
 Bituminous black baking japans 537 
 Bituminous cements..........%> 537 
 Bithmimous painte.es. fu. saeco 
 Bituminous varnishes........... 536 
 « Blaek. baking’ -Ja pans. -35t ose At 
 Boiling point of lacquers........ 610 
 Bolton’s method for tung oil test- 
 tin? cal een Ges tia cis pee 434 
 Bone DICK 6a Sha civ aty Wen a 758 
 Break. test: ‘tn oleic. ae 407 
 Brightness of pigments........ 19-24 
 Brush-cleaning device........... 296 
 Brushing tests on lacquers...... 619 
 Bulking value of paints........ 146 
 
 Bulking value of paint liquids... 150 
 Bulking value of pigments.. .144, 145 
 
 Cements, Bituminous..... By Dee 
 Cement test, Super-accelerated.. 391 
 Chemical examination of fossil 
 
 YTESIDN - 5 Ula ae ne ees ee 492. 
 Chevreul’s color chart.......... 224 
 Chrome Oxide green............ 751 
 Chreme<cyellew iia 205 tei oe 753 
 Chromium pigments............ 736 
 
 Chrysanthemists color system.... 2 
 Clarity test, Toluol insolubility, 
 TOF SPORID..GS os aoe 511 
 Cleaning brushes... 652. vier. css sn ee 
 Clemens hardness apparatus.... 60 
 Coarse particles in paint pig- 
 
 SYHOTIUS 2 ER. vidas whee emir ueie ae eae 151 
 Coleman-Fellows method for oil 
 contentvor. flaxseed 25.0.0. ees 570 
 Color comparisons of resins.... 510 
 Color” :Giscusston 7 o's. eae cee 250 
 Color, Graphical representation 
 
 0 iy BERS. Renee ae Soe 241, 246, 248, 249 
 Color number of dry pigments, 
 
 a! Wied Alle ip catia bodes ne aeraee 649, 652-654 
 Color reference standards, Sec- 
 OQUUATY: J ca5. be Cee ee enetee 2905 
 Color of resin, Pfister method 
 TOP? o aed atalevracag Pere Rice ee 406 
 Color standards for varnishes.. 479 
 OLOL.” BY RUCNIN ioscan, cate ee LT 
 
 Color of white opaque pigments 300 
 
 Colored building materials, Tem- 
 perature! Of.4).4% scutes eae 289 
 Colored light affecting drying 
 Age a0 ak ee oe eee 119 
 Colorimeters) 2c iecs.. tae eee PAE 
 Commercial para red........... 734 
 
 Comparison of lithopones for dar- 
 
 kening. jc:i025 «4s Bee eee 212 
 Consistency of paste paints... .49-51 
 Consistometers. 3.) .4lvs aes 37 
 Constants of. ol1S.<4.-450e ee 401 
 Controlling thickness of films.... 108 
 Conversion tables. .........5 298, 299 
 Copper paints, Methods of test- 
 
 Ing, u's onleslelets Shee was) OSU 
 Coumarone “PeSilivcy.. sone eee 497 
 
 Croll method for tinting strength 302 
 Croll-Jenkins accelerated testing 
 cabinet... 24 ee oid ane oe 323 
 
 Darkening of lithopone.......... 200 
 Darkening of shellac solutions.. 531 
 Definitions, A. S. T. M. Standard, 
 
 of terms used in paint specifi- 
 
 cations, \.~. cco eee 768 
 Destructively distilled turpentine, 
 
 A. S. T. M. tentative specifi- 
 
 cations ‘ f0ts-.5% pan ee eee «s DOG 
 Determination of rosin in shellac 520 
 Diagram of Pfund cryptometer.. 16 
 Dipping tank tests on film thick- 
 
 ness 
 Discoloration of interior whites 284 
 Discussion of coarse particle de- 
 
 terminations *) 4.4; 6ee eee 152 
 Dispersion test for tung _ oil, 
 
 Holley ...oss0.00) eee 433 — 
 Doolittle viscometer............ 33 
 Doping systems for airplanes.... 394 
 Dried volume weight of pig- 
 
 ments 05 Sessa eee 146, 147 
 Driers affecting color....... i+. 
 
 Driers affecting viscosity ...... 1179 
 Driers, Effect of on enamels.... 
 Driers in varnish. ..... noon : 
 Driers, mixed, Analysis of. . aes 485 _ 
 Drip method for melting point : 
 
 Of rosin... -au sein ewe ees 5144 
 Drying time cabinets, 124-126, 128, 130 3 
 
 Drying time comparisons. 117 
 Drying time of filmsie.n se ou . MG 
 Dry ted lead... 23.15 areas 
 
 du Pont scratch testing machine 69 — 
 
 Eastman Universal Colorimeter. 232 — 
 Effect of driers in varnish...... 1187) 
 Effect of driers on enamels...... 467 
 Elasticity or toughness, A. 8. T. 
 M. tentative method of test for 
 by addition of linseed oil..... 477 
 Elasticity or toughness of var- 
 nishes by addition of linseed 
 
 PPE 417 
 Elongation tests... .:.1ee sen eee 97 
 Enamels, Black baking........ . 548 
 Enamels, Effect of driers on.... 467 — 
 Ester gum.o...550 eee 496 
 Evaporation of solvents from lac 
 
 quers, Speed of, so .9e eee «« Gen 
 
Index 
 
 7735 
 
 SSS SS SSS 
 
 Examination of flaxseed........ 
 Examination of lacquer pigments 
 Examination of snirit varnishes 
 patunation of _turpentine and 
 ee rination of waxes and pole 
 
 OS A er 
 Exposure tests Petia 
 Exposure tests, Forest Products 
 
 Porting results. Ret end : 
 Exposure tests on “Tacquer plas.” 
 
 MN rs ia) ds) 5.6 eon 
 Iixposure tests on resins... 502-5 
 Jxposure tests on wood....... 
 Exterior exposure of lacueqred 
 
 mood panels,........... 
 
 Falling weight—torsion type—ef- 
 flux type—G. HE. type visco- 
 meters 2 oe ee ae 
 
 Fasig oil absorption number... 
 
 Federal specification for roof 
 RENE ig ce ye wn es eas 
 
 Figuring bulking value of paints 
 
 Film Spinning device............ 
 
 Film testing machine. . 
 
 Haim thickness........... 
 
 Film thickness as affected by 
 speed of withdrawal......... 
 
 Fineness determinations, Thomp- 
 son method. 
 
 oo ee eeveee 
 
 eee e eer ee eee eee ee 
 
 Fixed oils and resins in varnish 
 
 Flash point of lacquers 
 Flash point of volatile flam- 
 mable liquids, A. S. T. M. stan- 
 dard method of test for...... 
 Flaxseed, Examination of...... 
 Flaxseed, Oil content of, Cole- 
 man-Fellows method for...... 
 Flowmeter for mobility tests.... 
 Fogging tests on lithopone...... 
 Foots in linseed oil.... 
 Foots test, Jamieson-Baughmann 
 method soe 
 Forest Products Laboratory 
 on painting lumber .... 
 Fossil resins, Chemical examina- 
 Men Ol. ...... 
 Rerigniiy OF resins............ 
 
 eooesr eee ee 
 
 eoeee ee eee eee ee eee 
 
 tests 
 
 oeereere ee eee eee ee 
 
 Gallie-Porrit apparatus for coarse 
 particles 
 Galvanizing tank tests.......... 
 Gardner abrasion test..... 
 Gardner accelerated testing wheel 
 Gardner-Coleman oil absorption 
 a 
 Gardner color-change cabinet.. 
 Gardner drying time meter..... 
 Gardner flowmeter..... 
 Gardner-Parks film tester....... 
 
 ees eee ee 
 
 569 
 591 
 
 455 
 
 565 
 569 
 
 85 
 309 
 
 266 
 284 
 111 
 5d 
 97 
 
 Gardner-Parks mobilometer..... 
 Gas resistance of varnishes.... 464 
 Gel test on aluminum stearate... 664 
 Gold bronze powder..... a ed hae | 
 Gloss measurements on paint 
 
 89, 91-93 
 Glycerin tests on lithopone... 209 
 Green’s method for particle size 165 
 
 39 
 
 Green’s photomicrographic meth- 
 
 CMA SURE ia, SNe tie ae AeA ea as ie ete LOD 
 GUnl acerondés, 6.ccaa. « eae .. 496 
 Hallett hiding power meter. 24 
 Hardie recording spectrophoto- 
 
 BIGLOT: Wecseciti a cine se We se Tien ataet HOU 
 Hardness and abrasion resistance 59 
 Hardness of synthetic resins.... 499 
 Hardness tests on enamels...... 68 
 Hardness tests on varnishes... 68 
 Hess-Ives tint photometer...... 254 
 Hexabromide test cooperative 
 
 WOLK eS Ajes iL avioe ct eee ee tae 
 Hexabromide test for linseed oil 415 
 Hexabromide test on oils, Bail- 
 
 WIV ESUA trestae pte sot ea SN eee Ua ee Me RD 
 Hexabromide test, Steele-W ash- 
 
 DUTY Vice elo aerate cee wohl @ he Pete CLO 
 Hickson penetration consistency 
 
 BOSE We ceetice ae es 4 et Nee Ve ee pny 
 Hiding power and brightness 9, 662 
 Hiding power and brightness of ; 
 
 MISMeNES <)es os PS waved atee ee LOM ee 
 Hiding power comparisons ....28-30 
 Hiding power instruments..... 13 
 Hiding power of pigments..... 27 
 Holley dispersion test for tung oil 433 
 Hopkins-Murphy accelerated test- 
 
 INE pr CADINGE 2s Sime se ce de cee 
 Howland colorimeter............ 240 
 Humidity from various salt solu- 
 
 Lis 2 Yon CaO Cltags ake PL ee ay gO 8 Fr" 
 Impact testing machine........ 282 
 Ingersoll glarimeter............ 90 
 Inhibitive value of pigments.... 369 
 Insoluble matter in rosin, Tests 
 
 NEV ean Saari SaaS Hc gee uae (rem 
 Insulating value of coated pipes, 
 
 Testing Of iio ess Air hie Banya Hangs 4 1 
 INSUlAtINne VAINISH ee 4 ce en oe 4D 
 Insulating varnish, A. S. T. M. 
 
 tentative method for testing.. 458 
 Insulating varnish using ozone... 119 
 Interfacial tension ..-.-..... 174, 177 
 Iron and Manganese pigments, 
 
 A. S. T. M. Standard methods 
 
 Of: (ANALYSIS. 5/000 ~ Vin vana abe xchel a ted A 
 Iron are tests for lithopone 208, 20S 
 Iron are tests on white pigments 215 
 Tyes -eolorimeter 0s viecmie sis see eee 
 Jamieson-Baughmann foot tests 409 
 Japans,: Black baking... .cc.s DBT 
 
Index 
 
 776 
 Kauri reduction test, Effect on 
 
 SX DOSUTE Tal cx cbs ae alee 477 
 Keuffel & Esser color analyzer... 244 
 Keuffel & Esser spectrophoto- 
 
 WOTOT: ys iis ccale ws ewe whee eed oe 244 
 Laboratory hardness scratch 
 
 LORTOR hod oleh ai odact re Cotas oo = Wee 61 
 Lacquer analysis, Schemes for 
 
 OG asks du: asl Oy eta eas eee 597, 605 
 Lacquer coating, Low tempera- 
 
 ture LOSS: ONy . is ate etnce este ae 617 
 Lacquer diluents, Sampling and 
 
 festine  ys.45 (eee ees eee 592 
 Lacquered wood panels, Method 
 
 Of “TOSting ./ ote csi eee eee 387 
 Lacquer enamels, Testing of for 
 
 physical properties........... 621 
 Lacquer films, Physical tests on 616 
 Lacquer liquids, Physical prop- 
 
 erties Of. 5 ink nis vote eee 610 
 Lacquer materials, Solubility and 
 
 miscibility Of... situate es 598, 599 
 Lacquer pigments, Examination 
 
 OE Sa ov Wn 2p oa Se ee 691 
 Lacquer. plasticizers, Exposure 
 
 tests FONs sage ee oe eee 615 
 Lacquer, Paper curl test for. 620 
 Lacquer raw materials, Testing 579 
 Lidequer Tess. ses ys ss wees 502 
 Lacquer solvents and diluents, 
 
 A. S. T. M. tentative methods 
 
 of sampling and testing...... 592 
 Lacquer solvents. Latent heat of 
 
 vaporization ‘of |... sachs sees 627 
 Lacquer solvents, Miscibility of © 
 
 he phere ihe SER 598, 600 
 
 Lacquer solvents, Refractive in- 
 
 GEES OL ooh s oh ths See 610 
 Lacquer solvents, Testing....... 592 
 Lacquer solvents, Vapor pressure 
 
 OF Er i ee eee 631 
 Lacquer testing on wicker panels 388 
 Lacquer vapors, Testing the flash- 
 
 ines Of beets eee ee be oe ee 625 
 Lacquers, Bending tests on.... 618 
 Lacquers, Boiling point, flash 
 
 point’ and: -gravity of222...49 610 
 Lacquers, Brushing tests on.... 619 
 Lacquers, Materials used in 
 
 making. ....3 Pes ee ee ee 597 
 Lacauers. Miscellaneous physical 
 
 tests Olisi 5 a5 ConA vee ees 625 
 Lacquers .on ‘wWO0ds tas -ain nw ees 387 
 Lacquers, Physical tests on..... 612 
 Lacquers, Roof spray test on.... 386 
 Lacquers, Sanding tests on...... 620 
 Lacquers, Speed of evaporation of 
 
 solvents Trou... svn eaee ee 637 
 Lacquers, Spray test on........ 619 
 Lacquers, Tests of on metal.... 586 
 Lampblack sa..3 6. 20a ee ears ray 
 Latent heat of vaporization of 
 
 lacquer solventS=. 0. cise ees 627 
 
 Laurie-Bailey hardness apparatus 59 
 
 Leaded Zine oxide............ 700 
 Linseed oil addition test for 
 toughness or elasticity of var- 
 hishes.. s..8 ieee Are We . ATT 
 Linseed oil, Boiled......... saws een 
 Linseed oil, boiled, A. S. T. M. 
 tentative specification for..... 411 © 
 Linseed oil, Foots 1nl¢veean eee 405 
 Linseed oil, Hexabromide test for 415 
 Linseed. Oil, Raw... 2. 2esee seen 402 
 Linseed. oil, ‘raw; TAs Sotieoeee 
 tentative specification for..... 403 
 Lithopone 4 is 6. sees ees 701 
 Lithopone light resistance...... 193 
 Livering of varnishes..... adie 
 Lovibond tintometer............ 229 
 Low temperature tests on lac- 
 quer coatings: ...ci. ees ee 
 Maerz and Paul dictionary of 
 COlOT. 04s te bene ee ee 218 
 
 Maintaining color standards 256-258 
 
 Martens photometer........... 27-29 
 MeMullin accelerated testing 
 cabinet | .:.:. 233 ee eae eae 324 
 
 Melting and softening point of 
 rosin ..<.s) ae eee 512-515 
 
 Mercury-quartz tube tests on litho 
 
 PONE — ss dele we wa ce eee 195 
 Metal paint issGe eee eee ee 369 
 Metal, Preparation of for test.. 371 
 Metals and solvents, Effect of 
 
 upon darkening of shellae solu- 
 
 tious’. sobs oto eee ee ee ey 531 
 Mineral iron oxide. se aie ~. hae 
 Mineral. spirits 56.5 ene eee 564 
 Mineral spirits, A. 8. , M. tenta- 
 
 tive specifications for... eax. 564 
 Mineral spirits, Examination of 551 
 Miscellaneous methods of test- 
 
 ting materials... eae . 649 — 
 Miscellaneous physical testing de- 
 
 ViC@S 2%. cas) (ome eee 281 
 Miscellaneous physical tests on 
 
 lacquers:..« > +++ epee ee ee 625 
 Miscellaneous tests on varnishes 465 
 
 Miscibility of lacquer materials 
 ats lea Oe 598, 
 Mobility of lithopone ake ee 
 Moses-Harris charts..... 
 Munsell Atlas 
 Munsell syst@m..k wiece es sees 
 Nitrocellulose, A. S. T. M. recom- 
 mended tentative specification 
 for . 587 
 
 Nitrocellulose, Bulking value of 590 
 Nitrocellulose, Soluble.......... 587 
 Nitrocellulose solutions, Toler- ; 
 
 ance of to diluents....... 590 — 
 Nitrocellulose, Stability test. for 582 x 
 Nitrocellulose, Viscosity of...... 579 © 
 Nutting colorimeter....... . 2283 
 
 599 
 
 58 
 224 
 221 
 219 # 
 
 eeeeoe 
 
 fohespe =a 
 
Index 
 
 777 
 
 Ochre, A. 8. T. M. standard spec- 
 UNS 0 ea 766 
 
 Oil absorption, Gardner-Coleman 
 MEURIONE SCI WSs clas Fhe Wes See we LS 266 
 
 Oil absorption of pigments... .260-265 
 
 Oil absorption tests............ 259 
 Oil content of flaxseed, Coleman- 
 Fellows method fer.......... 570 
 Semeeisreak test Os. .0...... 66% 407 
 Pie OOUStATILS Of; 2.5, .%. 2.2.0.0 401 
 Oils, Physiological action of.... 663 
 Oleoresinous varnish........... 455 
 
 Oleoresinous varnishes, A. S. T. 
 M. standard method for test- 
 
 I ei ee Se ok a oe 455 
 Optical dispersion test on tung 
 
 ts oS eres eee y Scie vies «> 0 4 0% 435 
 Benes SHellaGs. ws. eset eee ee 516 
 Orange shellac, A. S. T. M. stand- 
 
 aro specification for.......... 516 
 Oxidation effects of ultraviolet 
 
 REMI Wie ipie ake rule 5 o's» ae 190 
 
 Ozone apparatus for drying var- 
 
 I 2 ne eae ae 119 
 fant ois, Analysis of......... 401, 
 armies DiLuUmInOUS..,. <2... e260 535 
 Palmerton accelerated testing 
 
 OSU Se pS ae 326, 330 
 
 Palmerton humidity ecabinet.... 122 
 Panel racks for baking tests.. 294 
 Paper curl test for lacquer.... 620 
 Papers on physical testing...... 296 
 Pari abrasion. test...........: 87 
 Particle size of pigments, 165, 173, 660 
 Particle size, Relation of yield 
 
 OO nee A a 1738 
 Particle size, sedimentation 
 
 PREM re ees tae oss eh ee 1¢2 
 Perilla oil, raw or refined, A. S. 
 
 T. M. standard specification 
 
 UE als db 2k at Sisto + «8s 443 
 Merroleig SPITits 2 o..e5 eek 564 
 Petroleum spirits, A. S. T. M. 
 
 tentative specifications for.... 564 
 Pfister method for color of resin 406 
 Pfund colorimeter for white pig- 
 
 Ee ios Gols a wb os ulig Gc kes 
 Pete erypcometer ............ 14 
 Pfund hardness meter.......... 82 
 Buero) type resis. .........5... 496 
 Photomicrographs of accelerated 
 
 PORES a es ee ks ese le-o10; S01, D008 
 Photomicrographs of coarse par- 
 
 SEM ec a ccc oe 10s 158-160, 163 
 
 Photomicrographs of exposed sur- 
 SS San ae ere 363-368 
 Photomicrographs of exposed var- 
 
 Ie NG ests... ~ + sO00-O08 
 Photomicrographs of hardness 
 ra 63-65 
 
 Photomicrographs of p2int pig- 
 NR ee hoo gia, yo 5 wary 0 166-169 
 
 id 
 
 Photomicrographs of screens.... 156 
 
 Physical properties of lacquer 
 LCL Sein certeetssencay en ane Saeco wees 610 
 Physical testing, Technical pa- 
 WOTSAOH Gis hee ets ee teas Neene 296 
 Physical tests on pyroxylin lac- 
 UCTS etait Ss oir ater ele 612 
 Physical tests on stripped lac- 
 POTTS ee wien org hee Sota s ees 616 
 Pigment analysis, Calculation of 
 PSU LL RRR, cOca es SRS I els saad he 693 
 
 Pigment photomicrographs. ...166-169 
 PRremenfp (COS UUILGs: s svete ate cs see's 276 
 Pigments affected by ultraviolet 216 
 
 Pigments, Analysis of 
 
 CUR TD ERWE EE yep een ace Beet fe Om ae mF 688 
 BMELMOUY c, OS IOC ox jarsdan.'s--3. 2 kets 684 
 PCAN wl cereale Gc ah ee uci ssaehire wo kas ee 709 
 DALE. (SOLU DEL See 2 ston aes 688 
 DS TRC lee. oo esl watts erat a tes ans ara ahd ok 756 
 PEs COWL Go tre areca ra ot stencil anit 742 
 DIUBSEIOO Chic. ocnara yeah cinuetere nue ele 743 
 
 blues, Prussian, Chinese, Ant- 
 werp, Milori, Bronze Steel.. 740 
 
 DIE sULETAALING eo cei e-otenaade fe TAL 
 CACHING CUG cS cs onto e elses 728 
 calcium pigments....708, 709, 715 
 CFIC SOLUDIG oc. 5. slerateie ee oe 688 
 CUT EEO Tee te nhe odes fe 9 aoa ang eee eta cnaes 756 
 Sarit (LOSI Gs 20m oisig cae 703, 713 
 chrome green ....... 744, 745, T46 
 chrome oxide green. ........« 749 
 ehrome, Vellow os; baieeeece 737 
 GCOLDTS, sh OTPAT IG. Soy iaaiascn whine 731-34 
 CUDTOUS OKICE. TE. wine s,0c8 oo x 730 
 STAD ILO tee sane set oie. de yeicas genase 756 
 PRhEa a7 PO Sa5 5 esti s eters ese ee es 761 
 lead chromate, basic....... <..- tod 
 leat.) meta llices cw peat a Abbe T04 
 BP Ss POU iy sone Se oae. Gre ie eae me T19 
 lead, red, Figg method........ T22 
 lead, red, Schaeffer method .. 725 
 UENO PONG: a sess y aes rend « scestyatent sue 706 
 lithopone, cadmium........... 729 
 masnesium,, soluble ..3, «2 <4. 689 
 Pit &l ANE Gs Robe an pe no Uae ERE et 763 
 Prince’s. metallic. ;40. 005 < nals os 761 
 TOU ONG vs eek ee alana 761 
 RELETIAIITRS oon 5 Sof tists ene oaks uae 728 
 SL BLT fe: she ech vy eke aciicaes Hu be ee ites 764 
 BRET UEC ieee hk ep et eka viadermcokerole elas 709 
 suifate: soluples. naan cease 690 
 STULL HOGS a ee eae katare wih nce eee 690 
 sulfur compounds, soluble..... 690 
 ODE GPR aN G WE2 D0 emir Ph enc cee A 691 
 EL CART Gs eels oe tetas ape acateee 710 
 TSE A TIS «5 erclraciay «thiol mis Tate caer ete 761 
 WM DOP sas ces Sie Sole Ree re eae 764 
 Venetian res oe.) ates ate ainsi 764 
 WEE TA LILOTE ie sc seed sieve ta ee peas 730 
 vermillion, American ......... text: 
 WATER: SSOLUDLG io. yctete cine ands ole 691 
 
778 
 
 Index 
 
 Pigments, Analysis of—continued 
 
 white lead, basic carbonate 703 
 white lead, basic sulfate..... T04 
 WHITE TOUGINE: 250. G5 te aan s oe 702 
 BING .PHTOMALE csc eek ae ee eee 748 
 PATIO PORCIEU D2, 1s asa rie ety bso oe 705 
 BING: ORTAE hye sare Geile o oie a,deetatne TO6 
 Pine, COAL soe od oes 5 egeetieees 688 
 Pigments, Color number of...... 
 Seehof Ca a - . 649, 652-654 
 Pigments, Inhibitive value of.... 369 
 Pigments, Oil absorption of. .260-265 
 Pigments, Particle size of....... 660 
 Pigments, Physical properties of. 300 
 Pigments, Settling properties of. 659 
 Pigments. Transmission of ultra- 
 violet light through....... 187, 188 
 Pigments, Wetting properties of 654 
 Physiological action of oils.... 663 
 Plasticizers, Laequer, Exposure 
 LOSUS CON <<a: als cles 2 a epee ete 615 
 Polishes. Examination of....... D795 
 Polymerized oils and resins in 
 WEPTUISD: o-..a. bo Meee eee ee 450 
 Polymer test for tung oil... 3:2. 435 
 P.. PP: G. consistency test... 2% eS 
 
 Practical color standards ....256-258 
 Preparation of films for hardness 
 
 GOST ache eect aetene wore ewe sere eh 
 Preparing metal for exposure 
 
 TeStS As eee at CR eee Sil 
 Primers for wood pene sae are 352 
 Print. test device. ok eee 281 
 Prupsiate- DING... +c fseca eet Sane, LEME 
 Pure Chrome ereen’.:.5 25.0.5 668 749 
 
 Pyroxylin coatings, Analysis of.. 595 
 Pyroxylin coatings, Materials pre- 
 
 BONE IN wy cys os loe Rat sea eee 597 
 Pyroxylin lacquers, Physical tests 
 
 (its coon sar, SCN e wists ted eet eee 612 
 Rack for draining panels...... 295 
 Raw materials in lacquer...... 579 
 Ret ogi e o i vanes oats «etl eee 496 
 Red: leatl ccs eee eee 718 
 Red lead primers for wood..... 352 
 Reduced chrome green......... 750 
 Refractive index >:...% .e5 ee ee 9 
 Refractive index of lacquer sol- 
 
 Vents. Ss Seg Bes ere ne nee 610 
 
 Refractive index of white pig- 
 
 MOUNT Keene ee : Suline: Spee ae 
 Refrigeration testing cabinet. 288 
 Refrigeration tests on paint.. 287 
 
 Relative method for particle size 173 
 Resins, Color camparisons of.... 510 
 Resin, Coumarone ....... 
 Resin and oil solutions, 
 ures on 503 
 Resins, Exposure tests on. . 502-509 
 Resins and fixed oils in varnish 449 
 Resins. Fossil, Chemical exami- 
 nation-Of..7.. Ae Pe eerie S| pak 
 
 Expos- 
 
 492 
 
 Resins, Fusibility of..........s. om 
 Resins in lacquers...i.:.20...0 eee 
 Resins, Miscellaneous ......496, 497 
 Resins other than fossil........ 495 
 Resins and polymerized oils in 
 
 varnish: ve... cee (oly ean 
 Resins. Solubility of..... 
 Resins, Solubility and miscibility 
 
 of in lacquer solvents... .599, 600 
 Resins, Synthetic, Exposure tests 
 
 On * -4)d aes oo eels akg 0 ores Oe 
 Resins, varnish, ‘Analysis of.... 488 
 Ridgway color system... mater |, 
 Roof coating, Analysis and spec- 
 
 ifications. for ©. s,s. 5 sates ae 
 Roof coatings, Federal mene 
 
 tion fOr ..65.627 eee . 546 
 Roof tests on galvanized pipe. «es O84 
 Rosin determination in shellac 
 
 rt) ME oe oe 520-529 
 Rosin drip method. Hic cee eee eee 
 Rosin in- shellac, Determination 
 
 Of 2 SS oe ee ra rriy bogie. 
 Rosin, Softening and melting 
 
 point Of <. aeeeuer veeacsve OL2-ts 
 
 Rosin, Tests for insoluble matter 511 
 Rosin, Toluol insolubility clarity 
 test for ne oe LR Rie oe 
 Rub-out test for oil absorption.. 260 
 Rust inhibitive value of pigments 369 
 
 Salt water, Effect of on metals 376 
 Salt water, Effect of upon painted 
 metals + pele Ht Banat 
 Sandarac resin...... ve bit eas se 
 Sanderson drying time meter... 113 
 Sanding tests on lacquers...... 620 
 Sapphire point hardness test... 62 
 Schemes for analysis of lacquer 
 : eee -areeeee .. 597-605 
 Secondary reference standards 
 for, Colt... 445035 scam uae ewes 
 Sedimentation method for par- 
 ticle -Siz@ .264 san eee oe 
 Service tests on varnishes...... 
 Settling properties of pigments.. 
 Shaded paper for hiding power 
 tests -.... cs tatele ete een 
 Shellac” sx so, eee 
 Shellac analysis. ........- 
 Shellac, A. S. T. M. standard 
 methods for testing. 
 Shellae, Orange, <A. S. T. M: 
 standard specification for.... 
 Shellac Rosin in, Determination — 
 Of gh sneame 6iack pe 
 Shellac solutions, Darkening of.. 
 Shellac varnish, A. S. T. M. ten- 
 tative method for testing.... 
 Shellac, Wax in. A. S. T. M. 
 tentative method for determi- 
 nation of 
 
 coo eevee eee 
 
 eoeoenreev ee 
 
 eos ee 
 
 wee eveeee 
 
 523 
 
 oeee er eee 
 
 aie 
 
 .. - 489-500 © 
 
 sno ve es se 
 Ships paints, Method of testing.. 377 
 
 i i canta ech: Wik ae cian Ta acai a eaten ee a ld i a ae hd eR 
 
 ce 
 7 
 
 Deh ae 
 
Index 779 
 Smoothness of white opaque pig- Synthetic resins, Solubility and 
 a ee ie ok uO properties’ Ofes Flees ols 498-500 
 Saal age oe pont Aa ee 515 Tanks for testing painted metal 
 ie See SUR MERR OO peel awe Sa Ae nae i: S74 
 Solubility of lacquer materials Temperature conversion tables.. 299 
 eae te 8 = = sl ea 598, 599 Temperature humidity control 
 Solubility and properties of syn- CALIROLS ivan erie eS ol nea re ibe 
 Siete TESS, oe cs iste ee 498-500 ‘Tensile strength of films....... 102 
 Solubility of resins............. 500 Tensile strength tests. 97 
 Solubility: of tung oil polymer.. 435 Terms used on reporting exposure 
 Solvent in varnish............. 448 TESTS cee cece eee cee eee eee eens 354 
 Solvents. and metals. Effect of Testing automobile black baking 
 upon darkening of shellac solu- CIISUOLENE ee Gar Good, "fe aacrneone ete atic 548 
 COR SS eae 531 ‘Testing colors for tone and 
 Solvents, Speed of evaporation of strength SMalisisieliatausl Sele ca lsinet Rete caiale 305 
 Srey IACHUELTS «0... sss a ss.. ia Leste COMPEr SPaINESs....7. pias yte 380 
 Soya bean oil, raw or refined, A. Testing durability of airplane 
 S. T. M. tentative specification doping systems.............. 394 
 oe See 439 ‘Testing effects of metals and sol- 
 Specific ‘gravity, A. S. T. M. vents upon darkening of shel- 
 ath le Ea el 136 FAC aypSONILIOUS > cere hare cine 6 5 ahs dol 
 Specific gravity of lacquers...... 709 «= Testing gas resistance of var- 
 Specific gravity of paint liquids 147 PLS eter ra ras tees 2/6 Wks woes eke a 466 
 Specific gravity of pigments .... Testing impact effects "mon films 282 
 (a ........ 144,145, 146 ‘Testing influence of thinners.. 477 
 Specific gravity, whirling method 143 Testing insulating value of 
 Specifications for aluminum ste- paints Saket iiatareuehe ceive lekdicheteiatetete (at stee 286 
 0 Te BG Sn 671 Testing lacquer enamels for phys- 
 Specifications, A. S. T. M., for RAI DLO DOE LOR Sts rota lageon tet eate 621 
 Pearse particles ............. 151 Testing lacquer solvents........ 592 
 Specification, A. S. T. M. for spe- Testing livering of varnishes.... 466: 
 1) SOS a a 136 Testing metals with accelerated 
 Spectrophotometers a eee aeawiag U7 POO LATS tals Sa el Geode a pw lea ame 374 
 Spectrophotometer, Hardie...... 259 Testing nitrocellulose lacquers on 
 Speed of evaporation of solvents PUM GA me oie aie tee oo, coil. a toon © casi Win 386 
 Brome 1acguers. ©. 2.05.2... ees 637 Testing paints for aluminum al- 
 Speed of evaporation of varnish JOYS secre e cece erect eens 381 
 ee... 471 Testing paints for cement  sur- 
 Spinning device for film thickness 109 faces, Accelerated method of.. 387 
 Spirit varnishes, Examination of 453 ‘Testing paints for refrigeration 
 Spray test on lacquers.......... 619 TOSSES Aiea ae Sled os Ooms 287 
 Stability of nitrocellulose...... 582. ‘Testing physical properties and 
 Standard oil absorption test.... 260 solubility of synthetic resins.. 495 
 Steam distilled turpentine, A. S. Testing raw materials in lacquer 
 T. M. specifications for...... 556 MARWEACLULE. — feraste <ipts wise wees 579 
 Steele modification for rosin in Testing resistance of lacquers to 
 er 529 bending ....--.+-. sees esse ees 618 
 Steele-Washburn hexabromide Testing speed of evaporation of 
 |S RINE SS ee en 416 WATTS, thiNners 1. 6G. os. ee > 471 
 Strength and tone of colors.... 305 Testing temperature of colored 
 Stutz apparatus for ultraviolet building materials...) san% +. 5 289 
 NS Fag ie seals sta.e «9's 0 185 Testing the acid value of var- 
 Super-accelerated alkali-water nishes ..... SRM I RAR ar Ge . 465 
 a a NE a a 391 Testing the bulking value of 
 aeece en aaa 180 MiPFOCEUUIOSE "ee eying s Hae 590 
 Re ees sir agl ish Akl s ns ere Gictras Cn erdrta San 
 Swinging beam hardness test.... 70 Testing the light resistance of 
 Synthetic resins, Exposure tests . lithopone RA Ae Cay ae MEA ee 198 
 re rr 502-509 Testing the rust inhibitive value 
 Synthetic - resins, Hardness of.... 499 Of -DISMHONTIE 7.025% vnc eee hes 369 
 
780 
 
 Testing toxic compositions to pre- 
 
 Tent fOnLING.. scars eee O17 
 Pesting: tune ~ Ollss.4 = vale See wale 431 
 Testing white opaque pigments 
 
 for physical properties....... 300 
 Texture of pigments........-+e% 276 
 Thickness of wet films.......... 103 
 Thinners, -Influence of... 00 ess 477 
 Thinners, varnish, Speed of evap- 
 
 OTREION (Glcws. Are. ss ager ate 471 
 Thompson classifier for paint pig- 
 
 TOCNTS ee ou 5 5 Fela ee eee 161 
 Tinting power vs. hiding power 27 
 Tinting strength, Barton’s method 
 
 ij a ie ot Agel ways Bae i: 303 
 Tinting strength, Croll method 
 
 TOY . -«ctoainbe Ula ah oe a aes pe 302 
 Tinting strength of titanium pig- 
 
 TOU ESE ce ple 6 a eae ea eae 303 
 Tinting strength of white opaque 
 
 DISHES 2. ue. += + sae eae 301 
 Titanium-barium pigment....... 701 
 Nitanitim pigments. of. .kee ene 710 
 Titanium pigments, Tinting 
 
 Strength -of 7) Sisk cls ete es 303 
 Toch test for Tune Oilss. cea nu 435 
 Tolerance of nitrocellulose solu- 
 
 tions. £0 diluents... se seen ee 590 
 Toluol insolubility clarity test for 
 
 TOSEH: so. 4 ee es bee o11 
 Tone and strength of colors..... 305 
 Toughness or elasticity, A. S. T. 
 
 M. tentative method of test for 
 
 by addition of linseed oil...... ATT 
 Toxie compositions, Testing of on — 
 
 WOSSGIS Ty is d-aichwed © Shaun ge piace 377 
 Transparency of pigments to 
 
 ultraviolet: radiation... ...< <=... 184 
 Tri-metal’ Primers: 2 vias. sie s «aie 352 
 
 Tung oil, Apparatus for testing.. 431 
 
 Tung oil, Bolton’s method for 
 
 PORTING 754545. ¢ pea ee 434 
 Tung oil, Holley dispersion test 
 
 FOR ca Wise ee ae ee i eee 433 
 Tung oil Optical dispersion of.. 454 
 Tung oil, Polymer test for...... 435 
 Tung oil, raw, A. S. T. M. tenta- 
 
 tive specification for . 2.5 s2u.5 427 
 Tung oi}, Toch test for io... eee 435 
 Tung oil varnishes, Alkali in- 
 
 crease: tést c10T) iike nA tig 6 oe 470 
 Tungstone point hardness test.. 66 
 Purpentine 45.5 saves eee ees DOT 
 Turpentine, A. S. T. M. standard 
 
 methods of sampling and test- 
 
 15 6 pe MM ar CDRP an pis Ons 2 BST 
 Turpentine, Destructively distill- 
 
 CH WOU Sake pele s 7, eevee en nee 
 Turpentine, Examination of.... 551 
 Turpentine, Gum spirits of.... 556 
 Turpentine, Steam distilled...... 556 
 
 Index 
 
 named 
 
 Ultramarine blue.......... ss ols See 
 
 Ultraviolet effects on colored pig- 
 ments 
 
 WIdS 3... Hen ae ee 186 
 Ultraviolet light effects on pig- . 
 ments. +04 18a ee ar 215 
 
 Ultraviolet light oxidation effects 
 
 Ultraviolet light studies on paint 
 liquids 
 
 Ultraviolet light studies on paint 
 pigments > «i.e wae . Aor 
 
 Ultraviolet transmission of pig- 
 ments 
 
 Vapor pressure of lacquer sol- 
 
 Vents. ® srw eee ne a cies we) GU 
 Varnish, Acid number of........ 447 
 Varnish, AnalysiseGt,.77 <:.55e . 447 
 Varnish, “ASho ids... eee ee 
 Varnish, Exposure tests....... . 362 
 
 Varnish, Fixed oils and resins in 449 
 Varnish, Insulating, A. 8S. T. M. 
 tentative method for testing.. 458 
 Varnish, Polymerized oils and re- ~ 
 SINS . 1D (. s.5 sass. oie eee 
 Varnish resins, Analysis of .... 
 Varnish, Shellac, A. 8. T. M. ten- 
 tative methods of testing.... 
 Varnish, Solvent ine, .-es te aoee 
 Varnish thinners, Speed of evap- 
 
 oration “Of +0 Nei ee ee 471 
 Varnish viscosity affected by 
 
 driers... 6.3% eee eee 11Ts 
 Varnishes, Bituminous.......... 536 
 Varnishes, Color standards for.. 479 — 
 Varnishes, Gas resistance of.... 466 — 
 Varnishes, Influence of thinners 
 
 UPON: 45°s b e-ore. doen eae ATT 
 Varnishes, Linseed oil addition 
 
 test for toughness or elasticity 477 — 
 
 Varnishes, livering Of.........- 466 
 Varnishes, Miscellaneous tests on 465 
 Varnishes, oleo-resinous, A. 8. T. 
 
 M. standard method for testing 455 
 Varnishes, Spirit, Examination of 4538 
 Varnishes Testing the acid value 
 
 i) Nr 465 
 Varnishes, Tung oil, Alkali in- 
 crease~ test’ TOF. <7, saceunisee 468 
 Vehicle, Effects of on light resis- 
 tance of lithopohe.......4.0s8 198 
 Viscometer conversion charts.... 37 
 Viscosity conversion table...... 35 
 Viscosity of lacquers.......... 41 
 Viscosity of nitrocellulose..... . 579 
 Viscosity of paints... -seeeee . 42 
 Viscosity, plasticity and mobility, 
 Instruments. for... ae eee 3s 2a 
 Viscosity vs. mobility compari- 
 
 sons 
 
 ie ee te oe 
 
 ee ee 
 eet aan Sd 
 
 an erence ane ng Ae 
 
 Fi 
 
 pS ks bos 
 
 +. 
 
 ee ee eG ares 
 
 ‘as 
 
 SS sh BS eS Nig eT Beli alah nt a aes he 
 
 ie 
 
 Pia aah eg Pah yr 
 
Index 
 
 781 
 
 Leen ERE aeacaeeemmeaeenczeemeeeeeeeemmeeaesaeaa mamas cca ascaaacaaaaaaaaacacaaaammaaaaamamamsmcacmaaamamaaal 
 
 Volatile flammable liquids, Flash 
 point of, A. S. T. M. standard 
 
 mernod Of test for.........6. 
 Volume and weight cup......... 
 Walker-Hickson accelerated test- 
 0 OE 
 Walker-Steele-Hickson humidity 
 NN Cee aie gona 9 ¢ 00 6.80 ee 
 Men SCNCLING. 2. cn ccs se pene ee 
 Wax in shellac, A. S. T. M. ten- 
 tative method for determina- 
 ict ec ya 0.e:e 'ci'e. 00 
 Waxes and polishes, Examina- 
 
 TR ee es Ss ait ecw cle ee 
 
 Wetting properties of pigments, 
 Testing of with different liquids 654 
 
 White linseed oil paints....... 676 
 WV LO DIS UIENCH sac case tadele 5 ohama oa 702 
 Wiesel method for viscosity of 
 MILTOCOINTIOBC. same wie Ss Gasset ate 579 
 Wilkinson color-sound system... 221 
 Wilkinson pencil test for hard- 
 HORS ae id s siaeire +s cee wiaks 6 eh eke 61 
 Wood panels for testing paint.. 342 
 Ce UTI alekc so aeteie etaces fee ate 6 496 
 Yield of paint formulas........ 146 
 Yieldof saint liquids sc .00 +« 150 
 AACR RC eas Sache 's a) & arn elateeoeocage ee 699 
 
~~ 
 
S : * 
 y 
 - 
 # 
 - 
 ~ 
 , 
 . + ~~. 
 4 
 a> 
 ‘ P 
 As = 
 = > on 
 > re i 
 -~ * ihe 
 i 
 ¢ 
 & 
 - _ a 
 . “ ‘ 
 y 7" ut 
 
STANDARD AND MASTER SPECIFICATIONS 
 
 For USE OF DEPARTMENTS AND INDEPENDENT ESTABLISHMENTS OF THE 
 U. S. GoveERNMENT 
 OFFICIALLY ADOPTED OR PROMULGATED BY THE 
 
 fi 
 
 FEDERAL SPECIFICATIONS BoAarRD 
 
 *- 
 
 - The specifications issued to date, in so far as they are available at the 
 Government Printing Office, have been bound in this volume. The list is 
 Sates below : : 
 
 Rateirae’ cations 
 ES (Ciroular Board 
 re Edition Title 
 2 4a Third—Oil, Linseed, Raw. 
 5  Second—Basic Carbonate White Lead, Dry and Paste. 
 6 Second—Basic Sulphate White Lead, Dry and Paste. 
 tb ‘Third—Turpentine (Gum Spirits of Turpentine and Steam- 
 ____ Distilled Wood Turpentine). 
 
 |  Second—Zine Oxide, Dry and Paste. 
 _ Second—Leaded Zine Oxide, Dry and Paste. 
 
 - Third—Paint, White, and Tinted Paints Made on a White 
 
 Base, Semipaste and Ready Mixed. 
 _ Second—Red Lead—Dry and Paste. 
 _ Second—Ocher, Dry and Paste. 
 - Third—Paints, Iron Oxide and Iron Hydroxide. 
 ‘Third—Paint, Black, Semipaste and Ready Mixed. 
 a Third—Green Paint, Semipaste and Ready Mixed. 
 - Second—Volatile Mineral Spirits for Thinning Paints. 
 
 ‘Second—Composite Vehicle for Thinning Semipaste Paints 
 when the Use of Straight Linseed Oil is not Justified. 
 
 _ Fourth—Varnish, Spar, Water-Resisting. 
 . _ Second—Asphalt Varnish. 
 | ‘Second—Liquid Paint Drier. 
 _ Second—F lat Interior Lithopone Paint, White and Light 
 pints’ | 
 Second—Interior Varnish. 
 pt. 25, 1923.—Water-Resisting Red Enamel. 
 pt. 19, 1923.—Gloss Interior Lithopone Paint, White and 
 i Feb. 20, 1924. erttaniunm Pigment, Dry and Paste. 
 ps - Second—Paint, Olive Drab (Semipaste and Ready-Mixed). - 
 May 9, 1925.—Outside White Titanium-Zine Paint, Semi- 
 paste and Ready-Mixed. 
 
 ae May 9, 1925.—Putty. 
 Feb. 9, 1926 Shellac, Flake Orange. 
 | Feb. 9 1926.—Varnish, Shellac. 
 
 FOS 29, ‘1927. Ne einkoine Vellow cel Medium, and 
 ey Dry, Paste in Oil, and Paste in Japan). 
 
U. S. Gov't 
 Master 
 Specification 
 
 44 No. 4a 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 82 
 
 [3d Edition. Issued April 26, 1927] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 OIL, LINSEED, RAW! 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 4a 
 
 [Revised March 5, 1927] 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on February 3, 1922, for the use of the departments and independent 
 establishments of the Government in the purchase of raw linseed oil. 
 
 [The latest date on which the technical requirements of this revision of this specification shall become 
 mandatory for all departments and independent establishments of the Government is June 6, gee They 
 may be put into effect, however, at any earlier date.] 
 
 CONTENTS 
 
 1 
 1 
 Ill. Material and workmanship__.._._-.....___--___- ae lan aw ne Oe 2 
 ewe aeaieras TodUsronients. ee et ene “Os MNOS. BiG 2 
 Deewana mermnsertents. cee ee a ee ee on 2 
 VI. Methods of sampling, testing, and basis of purchase_..__.__.___-- 2 
 
 a MEE AS ie bc te pi AE ba aes ee a 2 
 a Se A ee ee ee 3 
 
 pg twas) lle iy i Ma Sk Ai Ld Gias Sk ae io 6 
 
 *Pesenieros Purchase. 5.0). 09 [D272 LL Doss leurs 8 
 
 DP RpaeenC iGreen t  e o tee me wh AM Re pei 8 
 MME TRS A ee TR a SO ae Se US NPE AEROS SHE > 8 
 
 I. GENERAL SPECIFICATIONS 
 
 _. There are no general specifications applicable to this specification. 
 
 II. TYPES | 
 This specification covers two types of raw linseed oil: A, normal 
 iodine number; B, high iodine number. 
 
 1 For boiled linseed oil see United States Government Master Specification for Boiled Linseed Oil, Fed- 
 _eral Specifications Board specification No. 475a, (B.8. Oircular No. 330.) 
 
 43256°—27 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 Ill. MATERIAL AND WORKMANSHIP 
 See detail requirements. 
 IV. GENERAL REQUIREMENTS 
 See detail requirements. 
 V. DETAIL REQUIREMENTS 
 
 Raw linseed oil shall be pure oil expressed from flaxseed, and shall 
 conform to the following requirements: 
 
 oots: 
 
 Mente wOll..- cpekcstckee ec anne act asoese eee oe neers per cent by volume.- 1,0: “eekeaseeeene 
 “@UChEU (ets Bay 0 NOI eee ae CRN e a oe ORE mMEE Reg Sy LN ale niry mene AE ANE fp ooee 4.0" cLiccesoweesoe 
 Specific gravity 15.5/15.5° C___....------------------------------- 2-02 neon n ee ene . 935 0. 9300 
 ‘Acid nam bet. ob eb eee coke cane ke pees Sateen 5 Soe, eM ee 
 
 Saponification number___.....----------------------------------------+2+2+5--20- 195. 0 189. 0 
 Unsaponifiable matter-......--.-------------------------------------- per cent_- Te OO fetes ae 
 
 Todinie number 1.2 ecb nce bine cece ees ae ae et eee eee boeken Wits kee eee 175. 0 
 Loss on heating at 105 to 110° C....---.--..------.-+.----------------- per cent... (Aba Hess de eee 
 OOlOT kk dade owe dwn nk wn sucdapeeccamcetonsss ses sap eee ee nese eee Not darker than a 
 freshly prepared solu- 
 
 tion of 1.0 g potassium 
 bichromate in 100 cc 
 pure concentrated 
 sulphuric acid (sp. 
 gr. 1.84). 
 
 1 When high iodine number type of raw linseed oil is specified by the purchaser, the iodine number must 
 be not less than 188 and the oil shall conform to all of the other requirements. te 
 
 VI. METHODS OF SAMPLING, TESTING, AND BASIS OF 
 PURCHASE 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available information to ascertain whether the material meets the speci- 
 
 fication. | 
 1. SAMPLING 
 
 The method of sampling given under (a) below should be used 
 whenever it is feasible to apply it. To meet conditions when (a) 
 is not applicable, method (6), (c), or (d) is to be used according to 
 the special conditions that obtain. Haat 
 
 (a) Durine Loapinc or Tank Cars oR FILLING OF CoNnTAIN- 
 ERS FOR SHIPMENT AT THE Factory.—The purchaser’s inspector 
 shall draw a sample at the discharge pipe where it enters the receiving 
 vessel or vessels. The total sample shall be not less than 5 gallons 
 and shall be a composite of small samples of not more than 1 pint 
 each, taken at regular intervals during the entire period of loading 
 or filling. | ee Se | 
 
 The sample thus obtained shall be thoroughly mixed, and from 
 this composite sample three portions of not less than 1 quart each 
 shall be placed in clean, dry glass bottles or tin cans which must be 
 
SPECIFICATION FOR RAW LINSEED OM, 3 
 
 filled with the sample and securely stoppered..with new clean corks 
 or well-fitting metal covers or caps. These shall be sealed and 
 labeled distinctly by the inspector, and one delivered to the buyer, 
 one to the seller, and the third held for check in case of dispute. 
 
 (6) From Loapep Tank Cars or OTuer LarGEe Vessets.—The 
 total sample shall be not less than 5 gallons and shall be a composite 
 of numerous small samples of not more than 1 pint each, taken from 
 the top, bottom, and intermediate points by means of a glass or metal 
 container with removable stopper or top. This device attached to 
 a suitable pole is lowered to the various desired depths when the 
 stopper or top is removed and the container allowed to fill. The 
 sample thus obtained is handled as in (a). | 
 
 (c) Barres anpD Drums.—Not less than 5 per cent of the 
 packages in any shipment or delivery of. barrels and drums shall be 
 sampled. The packages shall be shaken, rolled, and stirred to mix 
 the contents thoroughly. The samples from the individual containers 
 shall be taken through the bunghole or holes not less than 114 inches 
 in diameter bored in the head or side for the purpose. The appa- 
 ratus for drawing the sample shall consist of a glass tube about 1 
 inch in diameter and somewhat longer than the length or diameter 
 of the oil container, a conical stopper that will fit the glass tube and 
 is not more than )% inch long fastened to a stiff metal rod not more 
 than 4 inch in diameter and not less than 4 inches longer than the 
 glass tube. The stopper is lowered by the rod until it rests on the 
 bottom of the cask, the tube slipped down slowly over the rod, and 
 finally pressed on the stopper. By holding tube and rod, the column 
 of oil can then be removed. This process is repeated until the 
 required amount of samples is obtained, which shall be not less than 
 2 gallons. This is mixed and handled as in (a). 
 
 - (d@) SmMaut Containers, Cans, Etc., or 10 GaLLons or Less.— 
 Smali containers, cans, etc., of 10 gallons or less should be sampled 
 while filling by method (a) whenever possible. When method (a) is 
 not applicable, it is mutually agreed that: In all cases the total 
 sample taken shall not be less than 3 quarts. This shall be obtained 
 by taking at least one package from each lot of not more than 300 
 packages. The sample thus taken shall be thoroughly mixed and 
 subdivided as in (a). 
 . 2. TESTING 
 
 All tests shall be made on oil that has been thoroughly agitated 
 before removal of a portion for analysis. | 
 
 (a) Foots.—General test—With all materials ‘at a temperature 
 between 20 and 27° C., mix, by shaking for exactly one minute in 
 a graduated tube, 25 cc of the well-shaken sample of oil, 25 cc of 
 acetone, and 10 cc of acid calcium chloride solution. Then clamp 
 ‘the tube in an upright position and allow to settle for 24 hours. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 The temperature during this period should be between 20 and 
 27° C. The graduated tube shall be of not less than 70 ce capacity 
 and shall have at least 50 cc graduated in 0.1 cc. The diameter of 
 the tube shall be such that the 50 cc graduated portion shall be not 
 less than 40 cm or more than 60 cm in length. The volume of the 
 stratum lying between the clear calcium chloride solution and the 
 clear acetone and oil mixture is read to 0.1 ec or fraction thereof. 
 This reading multiplied by four expresses the amounts of foots 
 present as percentage by volume of the oil taken. 
 
 Heated oil—WHeat a portion of the oil to 65° C., hold it within 
 2° C. of that temperature for 10 minutes, then cool it to room tem- 
 perature (20 to 27° C.). Promptly make the general foots test as 
 described above. | 
 
 Chilled oil—Heat a portion of the oil to 65° C., hold it within 
 2° ©. of that temperature for 10 minutes, then place it in a clean, 
 dry bottle, stopper tightly, and place in a cracked ice and water 
 mixture (0° C.) for exactly two hours. At the end of this time place 
 the bottle in a large bath of water at 25° C. and keep it there for 
 30 minutes, then promptly make the general foots test as described 
 above. 
 
 (b) Spectric Gravity.—Determine at 15.5/15.5° C. by any con- 
 ‘venient method that is accurate within two points in the fourth 
 decimal place. | 
 
 (c) Acty Numper.—Weigh from 5 to 10 g of the oil. Transfer 
 to a 300 cc Erlenmeyer flask. Add 50 cc of a mixture of equal parts 
 by volume of 95 per cent ethyl alcohol and c. p. reagent benzol. 
 
 (This mixture should be previously titrated to a very faint pink 
 
 with dilute alkali solution, using phenolphthalein as an indicator.) 
 Add phenolphthalein indicator and titrate at once to a faint per- 
 manent pink color with standard sodium or potasstum hydroxide 
 solution. Calculate the acid number (milligrams KOH) per gram 
 of oil. . | | . 
 (d) Savonrrication Numper.—Weigh about 2 g of the oil and 
 transfer to a 300 cc Erlenmeyer flask. Add 25 cc of alcoholic sodium 
 hydroxide or potassium hydroxide solution. Put a condenser loop 
 inside the neck of the flask and heat on a steam bath for one hour. 
 Cool, add phenolphthalein as indicator, and titrate with 0.5 WV H,SO,. 
 Run two blanks with the alcoholic alkali solution. These should 
 check within 0.1 cc 0.5 N H,SO,. From the difference between the 
 number of cubic centimeters of 0.5 N H,SO, required for the blank 
 and for the determination, calculate the saponification number 
 (milligrams KOH required for 1 g of the oil), Sk ania 
 
 (ec) Unsaroniriaste Marrer.—Weigh 8 to 10 g of the oil and 
 transfer to a 250 cc long-neck flask. Add 5 cc of a concentrated 
 solution of sodium hydroxide (equal weights of NaOH and H,O) 
 
 tase 
 a, 
 
Saat NE ER": 
 
 1 
 
 WRB Gp SND GRE ADT mi root NS 
 ee ere Pe tet eee Pee Mae ie ty oleh 
 
 SPECIFICATION FOR RAW LINSEED OIL 5 
 
 and 50 cc of 95 per cent ethyl alcohol. Put a condenser loop inside 
 the neck of the flask and boil for two hours. Occasionally agitate 
 the flask to break up the liquid, but do not project the liquid onto 
 the sides of the flask. At the end of two hours remove the condenser 
 and allow the liquid to boil down to about 25 cc. 
 
 Transfer to a 500 cc glass-stoppered separatory funnel, rinsing 
 with water. Dilute with water. to 250 cc, add 100 cc of redistilled 
 ether. Stopper and shake for one minute. Let stand until the two 
 layers separate sharp and clear. Draw all but one or two drops of 
 
 _ the aqueous layer into a second 500 cc separatory funnel and repeat 
 
 the process, using 60 cc of ether. After thorough separation draw 
 off the aqueous solution into a 400 cc beaker, then the ether solution 
 into the first separatory funnel, rinsing down with a little water. 
 Return the aqueous solution to the second separatory funnel and 
 shake out again with 60 cc of ether in a similar manner, finally draw- 
 ing the aqueous solution into the beaker and rinsing the ether into 
 the first separatory funnel. 
 
 Shake the combined ether solution with the combined water 
 rinsings and let the layers separate sharp and clear. Draw off the 
 water and add it to the main aqueous solution. Shake the ether 
 solution with two portions of water (about 25 cc each). Add these 
 to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water 
 
 down to the stopcock and draw off until the ether solution just fills 
 
 the bore of the stopcock. Wipe out the stem of the separatory 
 funnel with a bit of cotton on a wire. Draw the ether solution 
 (portion wise if necessary) into a 250 cc flask and distill off. While 
 still hot, drain the flask into a small weighed beaker, rinsing with 
 a little ether. Evaporate this ether, cool the beaker, and weigh. 
 (The unsaponifiable oil from adulterated drying oils may be volatile 
 and as a consequence may evaporate on long heating. Therefore, | 
 heat the beaker on a warm plate, occasionally blowing out with a 
 
 current of dry air. Discontinue heating as soon as the odor of the 
 
 ether is gone.) 
 (f) Iopins Numser.—Place a small quantity of the sample in a 
 small weighing burette or beaker. Weigh accurately. Transfer by 
 
 dropping from 0.09 to 0.15 g of oil to a 500 cc bottle, having a well- 
 ground glass stopper, or an Erlenmeyer flask, having a specially 
 
 flanged neck for the iodine tests. Reweigh the burette or beaker 
 and determine the amount of the sample used. Add 10 cc of chloro- 
 form. Whirl the bottle to dissolve the sample. Add 10 cc of chloro- 
 form to each of two empty bottles or flasks like that used for the 
 
 sample. Add to each bottle 25 cc of the Wijs solution and let stand 
 
 with occasional shaking for one hour in a dark place at a temperature 
 of from 21 to 23° C. Add 10 cc of the 15 per cent potassium iodide 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 solution and 100 cc of water. Titrate with 0.1 N sodium thiosul- 
 phate, using starch as an indicator. The titrations on the two blank 
 tests should agree within 0.1 cc. From the difference between the 
 average of the blank titrations and the titration on the samples, and 
 the iodine value of the thiosulphate solution, calculate the iodine 
 number of the samples tested. (Iodine number is given in centi- 
 grams of the iodine to 1 g of sample.) ‘y 
 
 (g) Loss on Heatine at 105 To 110° C.—Place 10 g of the: oil 
 in an accurately weighed 50 cc Erlenmeyer flask and weigh. Heat 
 in an oven at a temperature between 105 and 110° C. for 30 minutes, 
 then cool and weigh. Calculate the percentage loss. This deter- 
 mination shall be made in a current of carbon dioxide. 
 
 (h) Cotor.—Prepare a fresh solution of 1 g pure potassium 
 bichromate in 100 cc of pure concentrated colorless sulphuric acid 
 (specific gravity 1.84). Place the oil and color solution in separate 
 thin-walled clear glass tubes of the same diameter (1 to 2 cm) to a 
 depth of not less than 25 cm and compare the depths of color by 
 looking transversely through the columns of — by ernst 
 light. 
 
 3. REAGENTS 
 
 (a) Acrtone.—Acetone that will pass the specification of the 
 United States Pharmacopoeia. 
 
 (b) Acto Caucrum Cutoripe SoLtution.—Saturate with calcium 
 chloride a mixture of 90 parts water and 10 parts concentrated hydro- 
 chloric acid (specific gravity 1.2). 
 
 (c) SranparD Sopium Hyproxipz So.utTion.—Prepare a stock 
 concentrated solution of sodium hydroxide by dissolving hydroxide 
 in water in the proportion of 200 g NaOH to 200 cc of water. Allow 
 this solution to cool and settle in a stoppered bottle for several days. 
 Decant the clear liquid from the precipitate of sodium carbonate 
 into another clean bottle. Add clear barium hydroxide solution 
 until no further precipitate forms. Again allow to settle until clear. 
 Draw off about 175 cc and dilute to 10 liters with freshly boiled 
 distilled water. Preserve in a stock bottle provided with a large 
 guard tube filled with soda lime. Determine the exact strength 
 by titrating against pure benzoic acid (C;H;COOH), using phenol- 
 phthalein as indicator. (See Bureau of Standards Scientific Paper 
 No. 183.) This solution will be approximately one-fourth normal, 
 but do not attempt to adjust it to any exact value. Determine its 
 exact strength and make proper corrections in using it. , 
 
 y (d) Auconotic Sopurm Hyproxrpr Soxvurion. —Dissolve pure 
 X sodium hydroxide in pure 95 per cent ethyl] alcohol in the proportion 
 of about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 
 
 a Te 
 
 3 ee ee 
 ae 
 
 wm, ome son 
 tract ete 
 
SPECIFICATION FOR RAW LINSEED OIL, a 
 
 the clear liquid into another bottle and keep well stoppered. This 
 solution should be colorless or only slightly yellow when used. 
 
 (e) StanparpD Sopium TutosutpHate Sotution.—Dissolve pure 
 sodium thiosulphate in distilled water that has been well boiled to 
 free it from carbon dioxide in the proportion so that 24.83 g crystal- 
 lized sodium thiosulphate will be present in 1,000 cc of the solution. 
 It is best to let this solution stand for about two weeks before stand- 
 
 Chemistry, Treadwell-Hall, vol. 2, 6th ed., p. 551.) This solution’ 
 
 will be approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust 
 it to exactly decinormal strength. Preserve in a stock bottle provided 
 with a guard tube filled with soda lime. 
 
 (f) Starcu SoLutTion.—Stir up 2 to 3 g of potato starch or 5 g 
 soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
 300 to 400 cc boiling water, and boil the mixture until the starch 
 appears to be dissolved. Dilute to 1 liter. 
 
 (g) Porasstum Jopipr Souturion.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 cc. 
 
 (h) Wiss Sotution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 
 in the solution no sensible excess either of iodine or more particu- 
 larly of chlorine over that required to form the monochloride. This 
 condition is most satisfactorily attained by dissolving in the whole 
 of the acetic acid to be used the requisite quantity of iodine, using a 
 gentle heat to assist the solution, if it is found necessary. Dissolve 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
 and is free from reducing impurities in the proportion so that 13 ¢ of 
 iodine will be present in 1,000 cc of solution. Set aside a small portion 
 of this solution while pure and pass dry chlorine into the remainder 
 until the halogen content of the solution is doubled. Ordinarily it 
 will be found that by passing the chlorine into the main part of the 
 solution until the characteristic color of free iodine has just been 
 discharged, there will be a slight excess of chlorine which is corrected 
 by the addition of the requisite amount of the unchlorinated portion 
 until all free chlorine has been destroyed. A slight excess of iodine 
 does little or no harm, but excess of chlorine must be avoided. 
 
 (1) Haur Normat Sutpauric Actp Sotution.—Add about 15 cc 
 of sulphuric acid (1.84 specific gravity) to distilled water, cool and 
 dilute to 1,000 cc. Determine the exact strength by titrating 
 against freshly standardized sodium hydroxide or by any other 
 accurate method. Either adjust to exactly half normal strength or 
 leave as originally made, applying appropriate correction. 
 
 a 
 “i, 
 ly 
 
 / 
 
 ardizing. Standardize with pure resublimed iodine. (See Analytical , 
 
 \ 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 4. BASIS OF PURCHASE 
 
 Material is to be purchased by weight or volume, as specified in 
 the contract. When purchased by volume, 1 gallon of oil shall mean 
 231 cubic inches at 15.5° C. 
 
 VII. PACKING 
 
 Packing shall be in accordance with commercial practice unless 
 otherwise specified. 
 VIII. NOTES 
 
 This specification supersedes that part of Federal Specifications 
 Board specification No. 4 (B. S. Circular No. 82, 2d ed.) which 
 covered raw linseed oil. For specification for boiled linseed oil, see 
 Federal Specifications Board specification No. 475a (B. S. Circular 
 No. 330). The specification for refined linseed oil contained in 
 Federal Specifications Board specification No. 4 (B. S. Circular No. 
 82, 2d ed.) 1s revoked. 
 
 For formulas and methods of using this material and information 
 regarding the use of other specification paint materials, see Bureau 
 of Standards Technologic Paper No. 274, entitled ‘Use of United 
 States Government Specification Paints and Paint Materials.” 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROX 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFYICE 
 WASHINGTON, D. C. 
 AT 
 & CENTS PER COPY 
 
 Vv 
 
DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 No. 84. 
 
 [2d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 BASIC CARBONATE WHITE LEAD, DRY AND PASTE. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 5. 
 
 This Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 
 b Page 
 ee, a. eecuae « Boga’ deyad bean Gash 
 EERO ARID ae Pee 5 esse v Poe gh Rees Da ghh a hagh os ba oe Pepe eee 2 
 S-Laveratory examination of dry pigment: .. 002 ee a eas z 
 as Laperatoipiexaminaionio£ paste. O06. aloe. Os lo IOM a. lk 4 
 RIMES PA ee Soe Bae cs Oe Dey «cap wiry pte 4m AY Hid ylourd «\deinahy perece> 7 
 
 1. GENERAL. 
 
 _ Basic carbonate white lead may be ordered in the form of dry 
 pigment or paste ground in linseed oil. Material shall be pur- 
 chased by net weight. 
 
 - (a) Dry PicMentT.—The pigment shall be the product made 
 from metallic lead and shall have a composition corresponding 
 approximately to the formula 2PbCO,.Pb(OH),. It shall be 
 thoroughly washed after corroding, shall be free from impurities 
 and adulterants, and shall meet the following requirements: 
 
 106568 °—24 : 
 
2 Circular of the Bureau of Standards 
 
 Color—Color strength.—When specified, shall be equal to that 
 of a sample mutually agreed upon by buyer and seller. 
 
 Minimum, | Maximum. 
 
 Per cent. | Per cent. 
 Coarse particles retained on Standard No. 325 screen.......... 0... cece eect eee tpn eect neers 1.0 
 Teadl. carbomate. . icc 6 ics cc uk arsidns wccnd' nie 'o wilea ba elecutns > bie USN wis “ac.eaa Rear gs a 65. 0 75.0 
 Total impurities, including moisture...... 2.2... 0. ese nuesees vanerrsesaecee ass ahenees naps sue 2.0 
 
 (b) Paste.—The paste shall be made by thoroughly grinding 
 the above-described pigment with pure raw or refined linseed oil. 
 
 The paste as received shall not be caked in the container and 
 shall break up readily in oil to form a smooth paint of brushing 
 consistency. The paste shall consist of: 
 
 Moisture ‘and other volatile matter. - 22550 os ee sce hw wee seat p pn nO ea a 
 Coarse Sh ee and ‘‘skins’’ (total residue retained on No. 325 screen based on 
 PITMEHE) oo oie eases eid be weinle ep Sip ery na lalace Win gre ebb relm mBrm i eiene © Ch set a eee en 
 
 NotEe.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
 reserves the right to use any additional available information to ascertain whether the ‘material meets the 
 
 specification. 
 2. SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. 7 
 
 With the dry pigment, this package shall be opened by the 
 inspector and a sample of not less than 5 pounds taken at random 
 from the contents and‘sent to the laboratory for test. When 
 requested, a duplicate sample may be taken from the same pack- 
 age and delivered to the seller, and the inspector may — a 
 third sample to hold for test in case of dispute. 
 
 Whenever possible, an original unopened container shall be 
 sent to the laboratory with the paste; and when this is for any 
 reason not done, the inspector shall determine by testing thor- 
 oughly with a paddle or spatula whether the material meets the 
 requirement regarding not caking in the container. (See 4 (a).) 
 After assuring himself that the paste is not caked, the inspector 
 shall draw a sample of not less than 5 pounds of the thoroughly 
 mixed paste, place it in a clean dry metal or glass container, 
 which must be filled with the sample, closed with a tight cover, 
 sealed, marked, and sent to the laboratory for test with the 
 inspector’s report on caking in container. 
 
Specification for Basic Carbonate White Lead, Dry and Paste 3 
 3. LABORATORY EXAMINATION OF DRY PIGMENT. 
 
 (a) Coror.—Take 1 g of the sample, add 10 to 12 drops linseed 
 oil, rub up on a stone slab or glass plate with a flat-bottomed 
 glass or stone pestle or muller to a uniform smooth paste. ‘Treat 
 in a similar manner 1 g of the standard basic carbonate white 
 lead. Spread the two pastes side by side on a glass microscope 
 slide and compare the colors. If the sample is as white or whiter 
 than the ‘“‘standard,’’ it passes this test. If the standard is whiter 
 than the sample, the material does not meet the specification. 
 
 (b) CoLOR STRENGTH.—Weigh accurately 0.01 g of lampblack, 
 place on a large glass plate or stone slab, add 5 drops of linseed 
 oil, and rub up with a flat-bottomed glass pestle, or muller, then 
 add exactly 10 g of the sample and 45 drops of linseed oil, and 
 grind with a circular motion of the muller 50 times; gather up 
 with a sharp-edge spatula and grind out two more times in a 
 like manner, giving the pestle a uniform pressure. Treat another 
 0.01 g of the same lampblack in the same manner, except that 10 
 g of standard basic carbonate white lead is used instead of the 10 
 g of the sample. Spread the two pastes side by side on a glass 
 microscope slide and compare the colors. If the sample is as 
 light or lighter in color than the standard, it passes this test. If 
 the standard is lighter in color than the sample, the material does 
 not meet the specification. 
 
 (c) COARSE PARTICLES.*—Dry in an oven at 105° to 110° €. a 
 No. 325 screen, cool and weigh accurately. Weight 25 g of the 
 sample; dry at 100° C.; transfer to a mortar, add 100 cc kero- 
 sene, thoroughly mix by gentle pressure with a pestle to break 
 up all lumps, wash with kerosene through the screen, breaking 
 up all lumps, but not grinding. After washing with kerosene 
 until all but the particles which are too coarse to pass the screen 
 have been washed through, wash all kerosene from the screen with 
 ether or petroleum ether, heat the screen for one hour at 105 to 
 110° C., cool and weigh. 
 
 (d) QUALITATIVE ANALYsIS.—Test for matter insoluble in acetic 
 acid, zinc, calcium, etc., by the regular methods of qualitative 
 analysis. 
 
 - (e) MortstuRE.—Place 1 g of the sample in a tared wide-mouth 
 short weighing tube provided with a glass stopper. Heat with 
 
 1 For a general discussion of screen tests of pigments and data regarding many pigmentson the market, 
 see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
 the United States. 
 
4 Circular of the Bureau of Standards 
 
 stopper removed for two hours at a temperature between 105 and 
 110°C. Insert stopper, cool and weigh. Calculate loss in weight 
 as moisture. , 
 
 (f) Tora, Leap AND INSOLUBLE ImpuRITY.—Weigh 1 g of the 
 sample, moisten with water, dissolve in acetic acid. If any insol- 
 uble residue remains, filter, dry at 105 to 110° C. and weigh as 
 insoluble impurity. Dilute the solution to about 200 cc, make 
 alkaline with NH,OH, then acid with acetic acid, heat to boiling 
 and add 10 to 15 ce of aro per cent solution of sodium bichromate 
 or potassium bichromate, and heat until the yellow precipitate 
 assumes an orange color. Let it settle and filter on a Gooch 
 crucible, washing by decantation with hot water until the wash- 
 ings are colorless, and finally transferring all the precipitate. 
 
 Then wash with 95 per cent ethyl alcohol and then with ethyl — 
 
 ether; dry at 100° C. and weigh PbCrO,. Calculate to lead oxide 
 (PbCrO, X0.69=PbO). Total lead may be determined by the 
 sulphate method if preferred. 
 
 (g) CARBON Diox1bE.—Determine by evolution with dilute acid 
 and absorption in soda-lime or KOH solution, calculate CO, to 
 PbCO,, subtract PbO equivalent from total PbO and ratey 
 residual PbO to Pb(OH),. 
 
 CO, X 6.072 = PbCO, 
 
 C0, X% 5.072 =1ug 
 PbO \1.1o7 =P pC 
 PbO X1.08 =Pb(OH), 
 
 4. LABORATORY EXAMINATION OF PASTE. 
 
 (a) CAKING IN CONTAINER.—When an original package is 
 received in the laboratory, it shall be weighed, opened, and 
 stirred with a stiff spatula or paddle. The paste must be no 
 more difficult to break up and show no more caking than a normal 
 good grade of white-lead paste. The paste shall finally be thor- 
 oughly mixed, removed from the container, and the container 
 wiped clean and weighed. This weight subtracted from the 
 weight of the original package gives the net weight of the contents. 
 A portion of thoroughly mixed paste shall be placed in a clean 
 container and the portions for the remaining tests promptly 
 weighed out. 
 
 (6) MIxING witTH LINSEED O1r,.—One busiineds grams of the 
 paste shall be placed in a cup, 30 cc linseed oil added slowly with 
 
 a 
 
Specification for Basic Carbonate White Lead, Dry and Paste 5 
 
 careful stirring and mixing with a spatula or paddle. The result- 
 ing mixture must be smooth and of good brushing consistency. 
 (c) MoIsTuRE AND OTHER VOLATILE MatTrerR.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heat at 105 to 110° C. for three hours, cool and weigh. Calculate 
 loss in weight as percentage of moisture and other volatile matter. 
 (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
 of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
 “extraction mixture’’ (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, add 
 enough of the reagent to makea total of 60 cc in the tube. Place 
 the tube in the container of a centrifuge, surround with water 
 and counterbalance the container of the opposite arm with a 
 similar tube or a tube with water. Whirl at a moderate speed 
 until well settled. Decant the clear supernatant liquid. Repeat 
 the extraction twice with 40 cc of the extraction mixture, and 
 once with 40 cc of ether. After drawing off the ether, set the 
 
 tube in a beaker of water at about 80° C., or on top of a warm 
 
 oven for 10 minutes, then in an oven at 105 to 110° C. for two 
 hours. Cool, weigh, and calculate the percentage of pigment. 
 
 (e) EXAMINATION OF PiGMENT.—Grind the pigment from (d) 
 to a fine powder, pass through a No. 80 screen to remove any 
 ‘“skins,”’ preserve in a stoppered tube and apply tests 3(a), 3(d), 
 3(d), 3(f), and 3(9). 
 
 ({) PREPARATION OF Farry Acips.—To about 25 g of the paste 
 in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
 (see reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 
 on a steam bath until saponification is complete (about one hour). 
 
 Add 100 cc of water, boil, add sulphuric acid of specific gravity 
 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
 
 funnel to which some water has been previously added. Draw 
 off as much as possible of the acid aqueous layer and lead 
 sulphate precipitate, wash once with water; then add 50 cc 
 of water and 50 cc of ether. Shake very gently with a whirl- 
 ing motion to dissolve the fatty acids in the ether, but not so 
 violently as to form an emulsion. Draw off the aqueous layer 
 and wash the ether layer with one 15 cc portion of water and then 
 with 5 cc portions of water until free from sulphuric acid. Then 
 
 draw off the water layer completely. Transfer the ether solution 
 
 to a dry flask, add 25 to 50 g of anhydrous sodium sulphate. 
 
6 Circular of the Bureau of Standards 
 
 Stopper the flask and let stand with occasional shaking at a tem- 
 perature below 25° C. until the water is completely removed from 
 the ether solution, which will be shown by the solution becoming 
 perfectly clear above the solid sodium sulphate. Decant this clear 
 solution (if necessary through a dry filter paper) into a dry roo cc 
 Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
 CaCl, tower) into the mouth of the Erlenmeyer flask and heat ata 
 temperature below 75° C. on a dry hot eins until the ether is 
 entirely driven off. 
 
 Note.—It is important to follow all of the details, since ether generally contains 
 alcohol and after washing with water always contains water. It is very difficult 
 to remove water and alcohol by evaporation from fatty acids, but the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes both 
 water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
 from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (g) TEST FOR MINERAL O1,.—Place 10 drops of the fatty acid 
 (f) in a 50 cc test tube, add 5 cc of alcoholic soda (see reagents), 
 boil vigorously for five minutes, add 40 ce of water and mix. 
 A clear solution indicates absence of more than a trace of unsaponi- 
 fiable matter. If the solution is not clear, the oil is not pure 
 linseed oil. : 
 
 (h) IODINE NUMBER OF Fatry Acips.—Place a small quantity 
 of the fatty acids (f) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
 to a 500 ce bottle having a well-ground glass stopper, or an 
 Erlenmeyer flask having a specially flanged neck for the iodine 
 test. Reweigh the burette or beaker and determine the amount 
 of sample used. Add 10 ce of chloroform. Whirl the bottle 
 to dissolve the sample. Add 10cc of chloroform to two empty 
 bottles like that used for the sample. Add to each bottle 25 cc 
 of the Hanus solution (see reagents) and let it stand with occa- 
 sional shakings for one-half hour. Add 10 cc of the 15 per cent 
 potassium-iodide solution and 100 cc of water, and titrate with 
 standard sodium thiosulphate, using starch as indicator. The ti- 
 tration on the two blank tests should agree within 0.1 cc. From 
 the difference between the average of the blank titrations and 
 the titration on the sample, and the iodine value of the thiosul- 
 phate solution, calculate the iodine number of the sample tested. 
 (Iodine number is centigrams of iodine to 1 g of sample.) If 
 
Specification jor Basic Carbonate White Lead, Dry and Paste 7 
 
 the iodine number is less than 170, the oil does not meet the 
 specification. 
 
 (1) COARSE PARTICLES AND “SKINS.’’—Weigh an amount of 
 paste containing 25 g of pigment (see 4 (d)), add 100 cc kero- 
 sene, wash through a No. 325 screen and weigh the residue as in 
 3 (c). 
 
 5. REAGENTS. 
 
 (a) EXTRACTION MrxTURE— 
 , 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 I volume acetone. 
 
 (6) AguEous Soprum HyproxipE.—Dissolve 100 g sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 
 (c) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve 
 pure sodium thiosulphate in distilled water that has been well 
 boiled to free it from carbon dioxide, in the proportion of 24.83 g 
 crystallized sodium thiosulphate to 1,000 cc of the solution. 
 It is best to let this solution stand for about two weeks before 
 standardizing. Standardize with pure resublimed iodine.? This 
 solution will be approximately decinormal, and it is best to leave 
 it as it is after determining its exact iodine value, rather than to 
 attempt to adjust it to exactly decinormal. Preserve in a stock 
 bottle provided with a guard tube filled with soda lime. 
 
 (d) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 
 5 g of soluble starch with 100 cc of 1 per cent salicylic acid 
 solution, add 300 to 400 cc of boiling water, boil the mixture 
 until the starch is practically dissolved, and then dilute to one 
 liter. 
 
 (e) Porasstum IopIDE SoLuTION.—Dissolve 150 g potassium 
 iodide free from iodate in distilled water and dilute to 1,000 cc. 
 
 () Hanus SoLution.—Dissolve 13.2 g iodine in 1,000 cc of 
 glacial acetic acid, 99.5 per cent, which will not reduce chromic 
 acid. Add enough bromine, about 3 cc to double the halogen 
 content, which is determined by titration. The iodine may be 
 dissolved by applying heat, but the solution should be cold when 
 the bromine is added. 
 
 (g) ALCOHOLIC SoDIUM-HYyDROXIDE SoLuTION.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 
 2 See Treadwell-Hall Analytical Chemistry, II, 3d ed., p. 646. 
 
8 Circular of the Bureau of Standards 
 
 about 22 g per 1,000 cc. Let the solution stand in a stoppered 
 bottle. Decant the clear liquid into another bottle, and keep well 
 stoppered. This solution should be colorless or only slightly 
 yellow when used, and it will keep colorless longer if the alcohol is 
 previously treated with NaOH (about 80 g to 1,000 cc), kept at 
 about 50° C. for 15 days, and then distilled. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 5 CENTS PER COPY 
 V 
 
 WASHINGTON : GOVERNMENT PRINTING OFFICB : 1924 
 
 eT 
 
DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 No. 85. 
 
 [2d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 BASIC SULPHATE WHITE LEAD, DRY AND PASTE. 
 
 ee ee 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 6. . 
 
 This Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922,.for the use of the Departments and Independent Estab- 
 lishments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 
 Page 
 Es iy as sc go's wicca na sce a3 a2 Oe a he «Ps nn oe ee vig be I 
 reat eee, cee Pe pee, Soe OT AL? Qk 2B. aA NTIS 2 
 gsauotatory examination ofdry nigtidnt |) ). ch cpyscjice fi iy a boy brews om gee 2 
 4 Laboratory, examination of paste. 22). b: snips cas ete mite es ees 3 5 
 SO. Se OS AE ay PERRY SEE eh aaa eae reer! 7 
 
 1. GENERAL. 
 
 Basic sulphate white lead may be ordered in the form of dry 
 pigment or paste ground in linseed oil. Material shall be pur- 
 chased by net weight. | 
 
 (a) Dry Picment.—The pigment shall be the sublimed product 
 prepared from lead sulphide ores, free from impurities and adul- 
 terants, and shall meet the following requirements: 
 
 Color—Color Strength —When specified shall be equal to that of 
 a sample mutually agreed upon by buyer and seller. 
 
 Minimum. | Maximum. 
 
 Coarse particles: Per cent. | Percent. 
 Retained on standard Nor325 Screen. cas ces egs go erey wis gor ees - carps ereinn|s owtog. wer ase 1.0 
 Composition: 
 PRIOR GR oe ke hyiiclh tek Suhre eRe a Rai Gaia De GoE Sils ole ie BeBe Aiplan MOE s 11.0 18.0 
 Oe ef RS en eee ene ne gee Af Cam So mmnET een mR oc (re Peete 9.0 
 PEEL SIIEICIOE, ANUCIICING TOINOIO, 0 ois eas octets: crease mekeparenticelesctoneste be 1.0 
 
 The remainder shall be lead sulphate. 
 
 104952°—24——1 
 
2 Circular of the Bureau of Standards 
 
 (b) Pastes.—The paste shall be made by thoroughly grinding 
 the dry pigment with pure raw or refined linseed oil. 
 
 The paste as received shall not be caked in the container and 
 shall break up readily in oil to form a smooth paint of brushing 
 consistency. It. shall mix readily in all proportions without 
 curdling with linseed oil, turpentine, or volatile mineral spirits 
 or any combination of these substances. 
 
 The paste shall consist of: 
 
 Pigment ooo ooo ois. 0.0 2 0:50 van nian 9g W WclW/d 0°91 4:9 oo RINSING ln/e's a 6 lp aR ea ee 
 Linseed otk. i fi 55 oi ec 0 05 oes cle dS alsin in wiiooa 0 Bbeieiaee bite W nth nny tere eee satan a 
 Moisture.and other volatile matter. oc... .jn:cicw.sviarsin-o.ope osninpeapeigin.s aubiaebaee © © aig Aaa gee oer 
 Coarse 1 aa and “‘skins” (total residue retained on No. 325 screen, based on | — 
 
 PAP MMENE) oi. os ovis wip sigue vi evaiesn wbelpelacmin’y 01 n(eie!ovaryLavala: ply em mire w ne, 9 oy oiaimhanl a eens tatai ae 
 
 NotE.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
 teserves the right to use any additional available information to ascertain whether the waterial meets 
 
 the specification. 
 2. SAMPLING. : , 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. 
 
 With the dry pigment, this package shall be opened by the 
 inspector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. 
 
 With the paste, whenever possible, an original unopened con- 
 tainer shall be sent to the laboratory; and when this is for any 
 reason not done, the inspector shall determine, by thorough test- 
 ing with a paddle or spatula, whether. the material meets the 
 requirement regarding not caking in the container. (See 4a.) 
 After assuring himself that the paste is not caked in the container 
 the inspector shall draw a sample of not less than 5 pounds of the 
 thoroughly mixed paste, place it in a clean dry metal or glass con- 
 tainer, which must be filled with the sample, closed with a tight 
 cover, sealed, marked, and sent to the laboratory for test with =e 
 inspector’s report on caking in container. 
 
 When requested, a duplicate sample may be taken from ‘the 
 same package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 z 
 
 3. LABORATORY EXAMINATION OF DRY PIGMENT. _ 
 
 (a) Coror.—Take 1 g of the sample, add 10 to 12 drops linseed 
 oil, rub up on a stone slab or glass plate with a flat-bottomed glass 
 or stone pestle or muller to a uniform smooth paste... Treat in 
 
 a 
 - 
 ee ee a a 
 
Specification for Basic Sulphate White Lead, Dry and Paste 3 
 
 a similar manner, 1 g of the standard basic sulphate white lead. | 
 Spread the two pastes side by side on a glass microscope slide and 
 compare the colors. If the sample is as white as or whiter than the 
 “standard,” it passes this test. If the “standard”’ is whiter than 
 the sample, the material does not meet the specification. 
 
 (0) CoLOR STRENGTH.—Weigh accurately 0.01 g of lampblack,. 
 place on a large glass plate or stone slab, add 5 drops of linseed oil 
 and rub up with a flat-bottomed glass pestle or muller, then add 
 exactly 10 g of the sample and 45 drops of linseed oil and grind 
 with a circular motion of the muller 50 times; gather up with 
 _asharp-edge spatula and grind out twice more in a like manner, 
 giving the pestle a uniform pressure. ‘Treat another 0.01 g of the 
 same lampblack in the same manner except that 10 g of standard 
 basic sulphate white lead is used instead of the 10 g of the sample. 
 Spread the two pastes side by side on a glass microscope slide and 
 compare the colors. If the sample is as light as or lighter in color 
 than the “standard,” it passes this test. If the ‘“‘standard’”’ is 
 lighter in color than the sample, the material does not meet the 
 specification. 
 
 (c) COARSE PaRTICLES.“~—Dry in an oven at 105 to 110° C. a 
 No. 325 screen, cool, and weigh accurately. Weigh 25 ¢ of the 
 sample, dry at roo°C.; transfer to a mortar, add 100 cc kerosene, 
 thoroughly mix by gentle pressure with a pestle to break up all 
 lumps, wash with kerosene through the screen, breaking up all 
 lumps but not grinding. After washing with kerosene until all 
 but the particles too coarse to pass the screen have been washed 
 through, wash ali kerosene from the screen with ether or petroleum 
 ether, heat the screen for one hour at 105 to 110° C., cool, and 
 weigh. 
 
 (d) QUALITATIVE ANtAnwiis —Test for matter insoluble in 
 adi ammonium acetate solution, for calcium, for carbonates, 
 and for any other impurities suspected by the regular methods a5 
 qualitative analysis. 
 
 (e) MorstuRE.—Place 1 g of the sample in a tared, wide mouth, 
 short weighing tube provided with a glass stopper. Heat with 
 igh aie removed for two hours at a temperature between 105 and 
 110° C. Insert stopper, cool, and weigh. Calculate loss in weight 
 as moisture. 
 
 1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 
 
 see Circular No. 148 of the educational bureau, scientific section, Paint Manufacturers’ Association of the 
 United States. 
 
4 Circular of the Bureau of Standards 
 
 (7) INSOLUBLE ImpuURITY AND Tota, LEap.—In a 250 ce 
 beaker, moisten 1 g of the pigment with a few drops of alcohol; 
 add 50 cc of acid ammonium acetate solution. (See Reagents 
 5a.), Heat to boiling and boil for 2 minutes. Decant through a 
 filter paper, leaving any undecomposed matter in the beaker. To 
 the residue in the beaker, add 50 ce of the acid ammonium acetate 
 solution, heat to boiling, and boil for 2, minutes. Filter through 
 the same paper and wash with hot water. If an appreciable 
 residue remains, ignite and weigh as insoluble impurity. Unite 
 the acid ammonium acetate solutions, heat to boiling, and add 
 dropwise, with stirring, a slight excess (in total about 10 to 15 cc) 
 of dichromate solution. (See Reagents. 5b.) Heat until the 
 precipitate assumes an orange color, let settle, filter on a weighed 
 Gooch crucible, wash by decantation with hot water until the 
 washings are colorless, and finally transfer all of the precipitate 
 to the crucible. Then wash with 10 cc of 95 per cent ethyl 
 alcohol and finally with ro cc of ethyl ether. Dry at 110 to 120° 
 C., cool, and weigh PbCrO,.. Calculate to PbO by pulp iving | 
 by the factor 0.69. 
 
 (9) Zinc OxIpE.—Weigh accurately about 1 g of the pigment, 
 transfer to a 400 cc beaker, add 30 ce of HCl (1:2), boil for 2 or 
 3 minutes, add 200 ce of water and a small piece of litmus paper, 
 add NH,OH until slightly alkaline, render just acid with HCl, 
 then add 3 cc of concentrated HCl, heat nearly to boiling, and 
 titrate with standard potassium ferrocyanide as in standardizing — 
 that solution. (See Reagents 5d.) Calculate total zine as ZnO. 
 
 (h) LEAD SULPHATE.—Treat 0.5 g of the pigment in a 400 cc 
 beaker with a few drops of alcohol, add 10 ce of bromine water, 
 1occ of HCl (1:1), and 3 g of NH,Cl. Cover with a watch glass 
 and heat on a steam bath for 5 minutes, add hot water to give a 
 total volume of about 200 cc, boil for 5 minutes, filter to separate 
 any insoluble matter (a pure pigment should be completely dis- 
 solved), and wash thoroughly with hot water. (The insoluble 
 matter may be ignited, weighed, and examined qualitatively.) — 
 Neutralize the clear solution (original solution or filtrate from 
 insoluble matter) in a covered beaker with dry Na,CO,;, add 2 g 
 more of dry Na,CO,, and boil 10 to. 15 minutes. Wash off cover, 
 let settle, filter, and wash with hot water. Redissolve the precipi- 
 tate in HCl (1:1), reprecipitate with Na,CO, as above, filter, and 
 wash thoroughly with hot water. Acidify the united filtrates 
 with HCl, adding about 1 cc in excess. Boil to expel bromine, 
 
Sl eet re as icc 
 Pa eas oe 
 
 eee a gan 
 
 Be Raa 
 Hi ae 
 
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 Sein ae ale eppte SAS ae ih 
 
 Specification jor Basic Sulphate White Lead, Dry and Paste 5 
 
 and to the clear boiling solution add slowly with stirring 15 cc of 
 barium chloride solution. (See Reagents 5e.) Let stand on 
 steam bath for about one hour, filter on a weighed Gooch crucible, 
 
 wash thoroughly with boiling water, dry, ignite, cool, and weigh 
 
 as BaSO,. Calculate to PbSO,, using the factor 1.3. 
 (4) CaLcuLaTions.—Calculate the percentage of PbSO, to PbO 
 
 by multiplying by the factor 0.736:and subtract the result from 
 
 the percentage of PbO found under (f); report the difference as 
 
 PbO. Report ZnO found under (g) as percentage of ZnO. Mois- 
 
 ture and insoluble matter are reported as such.’ 
 4, LABORATORY EXAMINATION OF PASTE. 
 
 (a) CAKING IN CONTAINER.—When an original package iS 
 
 received in the laboratory it shall be weighed, opened, and stirred 
 
 with a stiff spatula or paddle. The paste must be no more difficult 
 to break up and show no more caking than a normal good grade of 
 white lead paste. ‘The paste shall be finally thoroughly mixed, 
 removed from the container, and the container wiped clean and 
 weighed. This weight subtracted from the’ weight of the original 
 package gives the net weight of the contents. A portion of the 
 thoroughly mixed paste shall be placed in a clean container and 
 the portions for the remaining tests promptly weighed out from it. 
 
 (b) Mrxinc with LInsEED Om.—One hundred grams of the 
 
 “4 paste shall be placed in a cup, and 3occ of linseed oil added slowly 
 
 with careful stirring and mixing with a spatula or paddle. The 
 resulting mixture must be smooth and of good brushing con- 
 sistency. 
 
 (c) MoIsTURE AND OTHER VOLATILE MATTER.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heat at 105 to 110° C. for three hours, cool and weigh. Calculate 
 loss in weight as percentage of moisture and other volatile matter. 
 
 (d) PERCENTAGE OF PIGMENT._-Weigh accurately about 15 g 
 of the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
 “extraction mixture” (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add 
 sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with water, 
 
 2 A method given by Schaeffer, J., Ind. and Eng. Chem., 6, p. 200 (1914), based on calculation of compo- 
 sition after determination of moisture, impurities, total lead, and total zinc oxide, issometimes used. This 
 method requires very accurate determination of Pb and ZnO, since the errors of determination are multi- 
 plied by approximately four in making the calculation to PbO and Pbsos. 
 
 104952°—24——2 
 
6 Circular of the Bureau of Standards ~ 
 
 and counterbalance the container of the opposite arm with a sim- 
 ilar tube or a tube with water. Whirl at a moderate speed 
 until well settled. Decant the clear supernatant liquid. Repeat 
 the extraction twice with 40 ce of extraction mixture and once 
 with 40 cc of ether. After drawing off the ether set the tube in 
 a beaker of water at about 80°C. or on top of a warm oven for 10 
 minutes, then in an oven at 105 to 1ro° C. for 2 hours, Cool, 
 weigh, and calculate the percentage of pigment. 
 
 (¢) EXAMINATION OF PicMENT.—Grind the pigment from (d) to 
 a fine powder, pass through a No. 80 screen to remove any “skins,” 
 preserve in a stoppered tube, and examine as under 3 (2), 3(6), 3(d), 
 3 (7), 3(9), 3(2), and 3 (2), Laboratory Examination of Dry Pigment. 
 
 (7) PREPARATION OF Farry Aciws.—To about 25 g of the paste 
 in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
 (see Reagents), and 75 cc of ethyl alcohol, mix, and heat uncovered 
 on a steam bath until saponification is complete (about 1 hour). 
 Add 100 ce of water, boil, add sulphuric acid of ‘specific gravity 
 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
 funnel to which some water has been previously added. Draw 
 off as much as possible of the acid aqueous layer and PbSO, 
 precipitate, wash once with water, then add 50 cc of water and 
 50 cc of ether. Shake very gently with a whirling motion to 
 dissolve the fatty acids in the ether, but not violently, so as to 
 
 avoid forming an emulsion. Draw off the aqueous layer and wash 
 
 the ether layer with one 15 ce portion of water and then with 5 ec 
 portions of water until free from sulphuric acid. Then draw off 
 completely the water layer. Transfer the ether solution to a dry 
 flask, add 25 to 50 g of anhydrous sodium sulphate. Stopper the 
 flask and let stand with occasional shaking at a temperature below 
 25° C. until the water is completely removed from the ether solu- 
 tion, which will be shown by the solution becoming perfectly clear 
 above the solid sodium sulphate. Decant this clear solution (if 
 necessary through a dry filter paper) into a dry 100 ce Erlenmeyer 
 flask. Pass a rapid current of dry air (pass through CaCl, tower) 
 into the mouth of the Erlenmeyer flask and heat to a temperature 
 below 75° C. on a dry hot plate until the ether is entirely driven 
 off. The fatty acids prepared as above should be kept in a stop- 
 pered flask and examined at once.* oer 
 *Itis important to follow all of the details since ether generally contains alcohol and after washing 
 with water always contains water. It is very difficult to remove water and alcohol by evaporation from 
 fatty acids, but the washing of the ether solution and subsequent drying with anhydrous sodium sulphate 
 
 removes both water and alcohol. Ether, in the absence of water and alcohol, is easily removed from fatty 
 acids by gentle heat. 
 
Specification for Basic Sulphate White Lead, Dry and Paste 7 
 
 (g) Test For MINERAL O1L.—Place 10 drops of the fatty acid 
 (j) in a 50 cc test tube, add 5 cc of alcoholic soda (see Reagents), 
 _ boil vigorously for 5 minutes, add 40 cc of water, and mix; a clear 
 solution indicates that not more than traces of unsaponifiable 
 matter are present. If the solution is not clear the oil is not pure 
 linseed oil. | 
 
 (h) IopIneE NuMBER oF Farry Acips.—Place a small quantity of 
 the fatty acids (f) in a small weighing burette or beaker and weigh 
 accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
 to a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
 meyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine the amount of sample 
 used. Add 1occ of chloroform and whirl the bottle to dissolve the 
 sample. Add 10 cc of chloroform to each of two empty bottles like 
 that used for the sample. Add to each bottle 25 cc of the Hanus 
 solution (see Reagents 5k) and let stand with occasional shaking 
 for one-half hour. Add ro ce of the 15 per cent potassium iodide 
 solution and 100 ce of water, and titrate with standard sodium 
 thiosulphate, using starch as indicator. ‘The titration on the two 
 blank tests should agree within 0.1 cc. From the difference be- 
 tween the average of the blank titrations and the titration on the 
 sample and the iodine value of the thiosulphate solution, calculate 
 the iodine number of the sample tested. (Iodine number is centi- 
 grams of iodine to 1 gof sample.) If the iodine number is less than 
 170, the oil does not meet the specification. 
 
 (1) COARSE PARTICLES AND ‘“‘SKINS.’’—Weigh out an amount 
 of paste containing 25 g of pigment (see d), add 100cc of kero- 
 sene, wash through No. 325 screen, and weigh the residue as 
 in 3 (c). 
 
 ef 5. REAGENTS. 
 
 (a) Acip AMMONIUM ACETATE SOLUTION.—Mix 150 cc of 80 
 per cent acetic acid, 100 ce of water, and 95 cc of strong ammo- 
 nium (specific gravity 0.90). : 
 
 _ (6) DicHROMATE SoLUTION.—Dissolve 100 g sodium dichro- 
 mate (Na,Cr,0,2H,O) or potassium dichromate (K,Cr,O,) in water 
 and dilute to 1,000 cc. 
 
 (c) URANYL INDICATOR FOR Zinc TITRATION.—A 5 per cent 
 solution of uranyl nitrate in water or a 5 per cent solution of 
 uranyl acetate in water made slightly acid with acetic acid. 
 
 _ (d) StanpDaRD Potasstum FERROCYANIDE.—Dissolve 22 ¢ 
 of the pure salt in water and dilute to 1,000 cc. To standardize, 
 
8 Circular of the Bureau of Standards 
 
 transfer about 0.2 g (accurately weighed) of pure metallic zine or 
 freshly ignited pure ZnO to a 400 cc\ beaker. Dissolve in to ec 
 of HCland 20 cc of water. Drop in a small piece of litmus paper, 
 add NH,OH until slightly alkaline, then add HCl until just acid 
 and finally add 3 cc of strong HCl. Dilute to about 250 cc with 
 hot water and heat nearly to boiling. Run in the ferrocyanide 
 solution slowly from a burette with constant stirring until a drop 
 tested on a white porcelain plate with a drop of the uranyl indica- 
 tor shows a brown tinge after standing 1 minute. A blank should be 
 run with the same amounts of reagents and water as in the stand- 
 ardization. The amount of ferrocyanide solution required for 
 the blank should be subtracted from the amounts used in stand- 
 ardization and in titration of the sample. The standardization 
 must be made under the same conditions of temperature, volume 
 and acidity as obtain when the sample is titrated. 
 (e:) Barrum CHLORIDE SoLuTION.—Dissolve 100 g of pure 
 crystallized barium chloride in water and dilute to 1,000 ce. | 
 (f) StanDARD SopruM THIOSULPHATE SOLUTION.— Dissolve pure 
 sodium thiosulphate in distilled water that has been well boiled to 
 free it from CO, in the proportion of 24.83 g of crystallized 
 sodium thiosulphate to 1,000 cc of the solution. It is best to 
 let this solution stand for about two weeks before standardiz- 
 ing. Standardize with pure resublimed iodine. (See Treadwell- 
 Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This solu- 
 tion will be approximately decinormal, and it is best to leave it as 
 it is after determining its exact iodine value, rather than to at- 
 tempt to adjust it to exactly decinormal strength. Preserve in a 
 stock bottle provided with a guard tube filled with soda lime. © 
 (g) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 
 g of soluble starch with roo cc of 1 per cent salicylic acid solu- 
 tion, add 300 to 400 cc of boiling water, and boil the mixture until 
 the starch is practically dissolved; then dilute to 1 liter. 
 (hk) Extraction MrxtuRE.—Mix ro volumes ether (ethyl ether), 
 6 volumes benzol, 4 volumes methyl alcohol, and 1 volume acetone. 
 (i) AquEous Soprum HyproxipE.—Dissolve 100 g of NaOH 
 in distilled water and dilute to 300 cc. . | 
 (7) Porassrum IoprpE SoLuTIoN.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 Cc. 
 (k) Hanus SoLuTion.—Dissolve 13.2 g of iodine in 1,000 cc 
 of glacial acetic acid, 99.5 per cent, which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, de- 
 
 ie. ita 
 
Specification jor Basic Sulphate White Lead, Dry and Paste 9 
 
 termined by titration (3 cc of bromine is about the proper 
 amount). The iodine may be dissolved by the aid of heat, but 
 the solution should be cold when the bromine is added. 
 
 (1) ALconoric Soprum MHyproxipE SoLuTion.—Dissolve 
 pure sodium hydroxide in 95 per cent ethyl alcohol in the propor- 
 tion of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
 Decant the clear liquid into another bottle, and keep well stop- 
 pered. This solution should be colorless or only slightly yellow 
 when used; it will keep colorless longer if the alcohol is previously 
 treated with NaOH (about 80 g to 1,000cc) kept at about SO on 
 for 15 days, and then distilled. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. ©. 
 . AT 
 5 CENTS PER COPY 
 
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 U. S. Gov’t 
 Master 
 Specification 
 
 No. 7b 
 DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 86 
 
 [3d, ed. issued October 11, 1926] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION 
 FOR TURPENTINE (GUM SPIRITS OF TURPENTINE AND 
 STEAM-DISTILLED WOOD TURPENTINE) 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 7b 
 [Revised August 7, 1926] 
 This specification was officially promulgated by the Federal Specifications 
 ‘Board on February 3, 1922, for the use of the departments and independent 
 
 establishments of the Government in the purchase of turpentine (gum spirits 
 of turpentine and steam-distilled wood turpentine). 
 
 [The latest date on which the technical requirements of this revision shall become mandatory for all 
 departments and independent establishments of the Government is November 7, 1926. They may be put 
 into effect, however, at any earlier date, after promulgation.] 
 
 CONTENTS 
 
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 BR SETTLE cee pent laes eeuer gs mien are a ine 
 CCE a eatin ah on pen pt cons a ead me = 
 VI. Methods of inspection, tests, and basis of purchase____-__------- 
 
 ee ee TI PGT os. in en ae en seh eps en wegen min 
 VIII. Notes.7- 59-4 PSAs. A 2. MAY VSS CRA Beas oe 
 
 I. GENERAL SPECIFICATIONS 
 
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 There are no general specifications applicable to this specification. 
 
 Hi. TYPES 
 
 This specification applies to two types of turpentine or spirits of 
 turpentine as follows: 
 
 A. Gum spirits of turpentine, commonly known as gum spirits. 
 This is the product distilled from the oleoresin exuding from living 
 
 - pine trees. 
 
 10413°—26—1 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 B. Steam-distilled wood turpentine, which is distilled with steam 
 from the oleoresin within the wood. 
 
 Il. MATERIAL. 1 1 4 970 
 No details specified. 
 IV. GENERAL REQUIREMENTS 
 There are’no general requirements applicable to this specification. 
 V. DETAIL REQUIREMENTS | 
 
 Gum. spirits of turpentine or steam-distilled dod turpentine, 
 as specified in contract, shall be pure and shall conform to the follow- 
 
 ing requirements: 
 
 APPEARANCE.—Shall be Senet and. free Pe poten intel 
 and water. | 
 
 Cotor.—Shall be standard”? or better. — 
 
 Opor.—Shall be mild, aromatic, and characteristic of the type of 
 turpentine specified. If desired, shall conform to the odor oh, the 
 sample agreed. upon. 3 sho Sex aiieebaliell 
 
 ae 4 
 
 ppb Bonsie geo | mum] mum 
 - LL LT TY ~ - —_——_— é 
 Specific gravity, 15.5/15.5° C...--- 2-22-22 sean ne ennesenecss sig oe eae eee 0. 875 0. 860 
 Refractive index. (Ma) at'20° C. ._.025 12 hn eee ge aa ee ee ae 1. 478 1. 465 
 Residue after polymerization with 38 N H2S0O4: . 
 Volume (per cexit) ...----- --22---2- = Ln SSE Se oe ZAP ue eeaeesees 
 Refractive index (Np) at 20° C _____..---.------- 2+ --- 5 =e on nn ns enn nn aa] nena seane= 1, 500 
 (This residue shall be viscous and its color straw or darker.) i AE Aca 4 
 Initial boiling point &f 760 mim’ preseure_2 2-4 Ste 160° C. T9" C..: 
 . 90 
 
 Distilling below 170° C. at 760 mm pressure eta CODE) ne op cx aceedtmmasode cesar uaa eee eae 
 
 VI. METHODS OF INSPECTION, TESTS, AND BASIS OF 
 PURCHASE 
 
 Deliveries will, in ene be inspected and tested by the Lsbowing 
 methods, but the purchaser reserves the right to use any additional avail- 
 able information to ascertain whether the material meets the aplication. 
 
 |. DETECTION AND REMOVAL OF SEPARATED WATER Taha 
 
 Draw a portion by means: of a glass-or,metal;container with a 
 removable stopper or top, or with a “thief,” from the lowest part 
 of the container, or by opening the bottom valve! of' thé perfectly 
 level tank car. If water is found to be present draw it all out, 
 record the quantity, and deduct it from the total volume of Jiquid’ 
 
 delivered. | 
 2, SAMPLING rwollot es snitnsdnys 
 
 The method of sampling given under (qa) should be used when- 
 ever feasible. When method (a) is not applicable method (6), 
 (c), or (d) is to be used, according to the special conditions that obtain. 
 
SPECIFICATION FOR TURPENTINE 3 
 
 (a) Waite Loapine Tank Car orn Wun Fitting Containers 
 FOR SHIPMENT.—Samples shall be drawn by the purchaser’s inspector 
 at the discharge pipe where it enters the receiving vessel or vessels. 
 The composite sample shall be not less than 5 gallons, and shall 
 consist of small portions of not more than 1 quart each taken at 
 regular intervals during the entire period of loading or filling. The 
 composite sample thus obtained shall be thoroughly mixed, and from 
 it three samples of not less than 1 quart each shall be placed in clean, 
 dry, glass bottles or tin cans, which must be nearly filled with the 
 sample and securely stoppered with new, clean corks or well-fitting 
 covers or caps. These shall be sealed and distinctly labeled by the 
 inspector; one shall be delivered to the buyer, one to the seller, and 
 the third held for check in case of dispute. 
 
 (6) From Loaprep TANK Car or OrHEr LarGcE VEsseu.—The com- 
 posite sample taken shall be not less than 5 gallons, and shall consist 
 of numerous small samples of not more than 1 quart each taken from 
 the top, bottom, and intermediate points by means of a metal or glass 
 container with removable stopper or top. This device, attached to 
 a suitable pole, is lowered to the various desired depths, when the 
 stopper or top is removed and the container allowed to fill. The 
 sample thus obtained is handled as in (a). | 
 ~ (c) Barrets AND Drums.—Barrels and drums shail be sampled 
 after gauging contents. Five per cent of the packages in any ship- 
 ment or delivery shall be represented in the sample. ‘Thoroughly 
 mix the contents of each barrel to be sampled by stirrmg with a 
 clean rod and withdraw a portion from about the center by means 
 of a “‘thief’”’ or other sampling device. The composite sample thus 
 obtained shall be not less than 3 quarts, shall consist of equal portions 
 of not less than one-half pint from each package sampled, and shall 
 be handled as in (a). Should the inspector suspect adulteration, he 
 shall draw the samples from the suspected packages. 
 
 (2) Smatt ContTarINers, Cans, ETCc., OF 10 GALLONS or LEss.— 
 These should be sampled, while filling, by method (a) whenever pos- 
 sible; but in case this is impossible the composite sample taken shall be 
 not less than 3 quarts. This shall be drawn from at least five pack- 
 ages (from all when fewer), and in no case from less than 2 per cent 
 of the packages. The composite sample thus taken shall be thor- 
 oughly mixed and subdivided as in (a). 
 
 3. LABORATORY EXAMINATION 
 
 (a) APPEARANCE.—Examine to determine compliance with the 
 specifications. 
 — (6) Cotor.—Fill a 200 mm perfectly flat-bottomed colorimeter 
 tube, graduated in millimeters, to a depth of from 40 to 50 mm with 
 
% 
 
 4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 the turpentine to be examined. Place the tube in a colorimeter and 
 place on or under it a No. 2 yellow Lovibond glass. Over or under a 
 second graduated tube in the colorimeter place a No. 1 yellow Lovi- 
 bond glass and run in the same turpentine until the color matches as 
 nearly as possible the color in the first tube. Read the difference in 
 depth of the turpentine in the two tubes. If this difference is 50 
 mm or more the turpentine is ‘‘standard”’ or better. | 
 
 (c) Opor.—Determine by comparison with the agreed-upon sam- 
 ple, which shall have been kept in the dark in completely filled, well- 
 stoppered bottles and free from separated water. 
 
 (d) Spuciric Graviry.—Determine at 15.5/15.5° C. by any con- 
 venient method that is accurate within 2 points in the fourth decimal 
 place. 
 
 (e) Rerractive [Npex.—Determine refractive index at 20° C. 
 with an accurate instrument. When the refractive index is deter- 
 mined at any other temperature, the readings obtained shall be 
 corrected to 20° C. by adding to or by subtracting from the actual 
 reading 0.00045 for each degree centigrade that the temperature at 
 which the determination was made is, respectively, above or below 
 20°C. 
 
 (f) DistrtLation.—Apparatus.'—Condenser.—The type of appa- 
 ratus (see fig. 1) adopted by the American Society for Testing Mate- 
 rials for the distillation of paint thinners other than turpentine, sub- 
 stituting for the thermometer there described? an immersed ther- 
 mometer such as is described below, is preferred. In case the A. S. 
 T. M. distillation apparatus is not available, use an ordinary straight 
 glass-tube condenser, about 22 inches long, with 16 inches in contact 
 with the cooling water. The end of the condenser tube should be 
 fitted with an adapter or should be bent down to a nearly vertical 
 position, and the tip should be cut off or ground down at an acute 
 angle. The tip should extend a short distance mto the receiving 
 cylinder. eh SARA 
 
 Flask.—Comparable results can be obtained only by using flasks 
 of the same dimensions. The distilling flask used shall be the stand- 
 ard Engler flask, as used for petroleum distillation, having the fol- 
 lowing dimensions: Diameter of bulb, 6.5 cm; cylindrical neck, 15 
 cm long, 1.6 cm internal diameter; side or vapor tube, 10 cm long, 
 0.6 cm external diameter, attached to neck at an angle of 75°, so 
 that when the flask contains its charge of 100 ce of oil the surface of 
 the liquid shall be 9 cm below the bottom of the junction of the side 
 tube and neck. , 
 
 Support for flask.—Support the flask on a plate of asbestos 20 
 cm in diameter, having an opening 4 cm in diameter in its center, 
 
 i Figure 1. 
 7A.S. T. M. Standards, p. 607; 1918. 
 
 a ee 
 
SPECIFICATION FOR TURPENTINE - 5 
 
 and heat with an open flame. Surround the flask and burner with 
 _a Shield to prevent fluctuation in the temperature of the neck of 
 the flask. Or, support the flask in a metal cup, 15 to 20 em in 
 diameter, containing high-boiling mineral oil or glycerin and fitted 
 with a concave cover having in the center. a circular opening 514 
 to 6 cm in diameter. In all cases take the necessary precautions 
 to prevent. fluctuation in temperature in the neck of the flask. 
 Thermometer.—The thermometer used for turpentine distillation 
 shall conform to the following specifications: 
 _. It shall be graduated from 145° to at least 200° C. in 0.2° inter- 
 vals... Thermometers graduated above 200° C. may be used, pro- 
 
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 ‘Fis. L —Dislitiation apparatus 
 
 idea Ser, hi sect rwiitle tbe following. ane eee Length, 
 -bottom: of thermometer to 175° mark, not more than 8 nor less than 
 6.5 cm. Length, top of bulb. to 145° mark, not less than 1.5): cm. 
 “Length, 145 to 175° mark, not more than 6 cm, 
 
 .. The. thermometer shall be made of suitable Jeiduachaniciie nye 
 and thoroughly annealed, so that the scale errors will not increase 
 after continued heating. 
 
 _ The thermometer shall be filled er the mereury with an. inert 
 gas, with sufficient pressure above the mercury column to prevent 
 breaking of the column. It shall have a reservoir at the top, so 
 thatthe pressure will not become excessive. at the highest 
 temperature. | 
 10413°—26——2 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 Every fifth graduation shall be longer than the intermediate 
 ones, and the marks shall be numbered at each interval of 5°. The 
 graduation marks shall be clear-cut and fine and the numbering 
 clear-cut and distinct. 
 
 The error at any point on the scale shall not exceed +0.5° C. 
 when tested for total immersion of the mercury column. 
 
 Receiving cylinder.—Collect the distillate in an accurately grad- 
 uated 50 or 100 cc cylinder. The so-called normal or precision 
 cylinder of 50 cc capacity, having an internal diameter of 1.5 em 
 and graduated in 0.2 cc, is preferred. If a cylinder with larger 
 inside diameter is used, a pasteboard cover with a hole for the con- 
 denser tube should be placed over the top. 
 
 Operation.—Place 100 cc of the turpentine and several small 
 pieces of pumice (or glass) in the distilling flask, fit the thermom- 
 eter so that the top of the mercury bulb is level with the bottom 
 of the side tube and the 175° C. (347° F.) mark is below the cork. 
 Place the flask in position on the asbestos board or oil bath and 
 connect with the condenser. Apply the heat cautiously at first, 
 and when distillation begins regulate the heat so that the turpentine 
 distills at the rate of not less than 4 nor more than 5 cc per minute 
 (approximately two drops per second). The initial boiling point 
 is the thermometer reading at the instant when the first drop falls — 
 from the end of the condenser. Discontinue distillation when the 
 temperature reaches 170.0° C. (338° F.), or an equivalent thereof, 
 depending on the atmospheric pressure, as outlined below; let the 
 condenser drain and read the percentage distilled. 
 
 The percentage distilled below successive selected temperatures 
 and the temperature at which each successive 10 cc distills may 
 also be determined if desired, making the necessary correction of 
 the temperature for variations in atmospheric pressure. ~ 
 
 Correction for variation in atmospheric pressure.—Since distillation 
 results are comparable only when obtained under exactly the same 
 pressure conditions, turpentine should be distilled at that pressure 
 which, at room temperature, is equivalent to a pressure of 760 mm 
 of mercury at 0° C. Whenever the barometric reading after correcting 
 to 0° C. is other than 760 mm a correction must be made. Since 
 alteration of the pressure in the distilling system requires rather 
 complicated apparatus, it is simpler to alter the temperature observa- 
 tion points to correspond to the prevailing pressure. 
 
 To determine what the barometric reading at the brcwailind room 
 temperature, or at the temperature of the barometer, would be at 
 0° C., read the barometer and thermometer alongside when about 
 to begin distillation. Refer to Table 1, page’7.. Under the column 
 nearest the observed pressure reading, and on the line nearest the 
 observed temperature of the barometer, will be found the correction 
 
SPECIFICATION FOR TURPENTINE 7 
 
 which must be subtracted from the observed pressure reading to 
 obtain the equivalent, or true, reading at 0° C. 
 
 The distilling temperature of turpentine is affected plus (+) or 
 minus (—) 0.057° C. for each millimeter variation of the barometer 
 above or below the normal 760 mm at 0° ©. If the barometer 
 reading after correcting to 0° C. is below 760 mm, the turpentine 
 will distill at a slightly lower temperature than under normal pressure. 
 Therefore, the temperature recorded at the beginning of distillation 
 (and any others observed during the course of the distillation) 
 must be corrected to get its equivalent at normal pressure. The 
 final temperature observation point (170° C. of the specifications) 
 must be altered accordingly to get its equivalent at the pressure 
 (corrected to 0° C.) at which distillation is made. 
 
 For example, if the barometer reading after correcting to 0° C. 
 is 750 mm, the correction of the observed initial distilling temperature 
 will be 0.057 X10=0.6° C., approximately. If the reading of the 
 thermometer when the turpentine begins to distill is 155.6° C. the 
 corrected initial distilling temperature will be 155.6° +0.6° = 156.2° C. 
 Furthermore, the temperature observation point at end of distillation 
 (170.0° C. at 760 mm) must be altered to the same extent. Since 
 the turpentine is distilling 0.6° C. below what it would at normal 
 pressure, distillation must be discontinued at 0.6° C. below the speci- 
 fied limit of 170.0° C. to determine the percentage distilling below 
 170.0° C. 
 
 TABLE 1.—Correction to barometer reading ! 
 {From circular F, instrument division, Weather Bureau, U. S. Department of Agriculture] 
 
 Tem- Observed reading of barometer, in millimeters 
 ' pera- 
 ture, 
 °C 640 | 650 | 660 | 670 | 680 | 690 | 700 | 710 | 720 | 730 | 740 | 750 | 760 | 770 | 780 
 
 15.0 | 1.56 | 1.59 | 1.61 | 1.64 | 1.66 | 1.69 | 1.71 | 1.74 | 1.76 | 1.78 | 1.81 | 1.83 | 1.86 | 1.88 | 1.91 
 16.0 | 1.67 | 1.69 | 1.72 | 1.75 | 1.77 | 1.80 | 1.83 | 1.85 | 1.88 | 1.90 | 1.93 | 1.96 | 1.98 | 2.01 | 2.03 
 17.0 | 1.77 | 1.80} 1.83 | 1.86 | 1.88 | 1.91 | 1.94 | 1.97] 1.99 | 2.02 | 2.05 | 2.08 | 2.10 | 2.13 | 2.16 
 18.0 | 1.88 | 1.91 | 1.93 | 1.96 | 1.99 | 2.02 | 2.05 | 2.08 | 2.11 | 2.14 | 2.17 | 2.20 | 2.28 | 2.26 | 2.29 
 19.0 | 1.98 | 2.01 | 2.04 | 2.07 | 2.10 | 2.13 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 | 2.32 | 2.35 | 2.38] 2.41 
 20.0 } 2. 9° 2.12 | 2.15 | 2.18 | 2.21 | 2.25 | 2.28 | 2.31 | 2.34 | 2.38 | 2.41 | 2.44) 247/251) 2.54 
 21.0 | 2,19 | 2.22 | 2.26 | 2.29 | 2.32 | 2.36 | 2.39 | 2.43 | 2.46 | 2.50 | 2.53 | 2.56 | 2.60 | 2.63 | 2.67 
 22.0 | 2.29 | 2.33 | 2.36 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2,58 | 2.61 | 2.65 | 2.69 | 2.72 | 2.76 | 2.79 
 23.0 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.62 | 2.66./ 2.69 | 2.73 | 2.77 | 2.81 | 2.84 | 2.88 | 2.92 
 24.0 | 2.50 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 |. 2.73 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 
 25.0 | 2.60 | 2.64 | 2.68 | 2.72 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 | 3.09 | 3.13 | 3.17 
 26.0 | 2.71 | 2.75 | 2.79 | 2.83 | 2.88 | 2.92 | 2.96 | 3.00 | 3.04 | 3.09 | 3.13 | 3.17 | 3.21 | 3.26 | 3.30 
 27.0 | 2.81 | 2.85 | 2.90 | 2.94 | 2.99 | 3.03 | 3.07 | 3.12 | 3.16 | 3.20 | 3.25 | 3.29 | 3.34 | 3.38 | 3.42 
 
 _ 28.0 | 2.91 | 2.96 | 3.00 | 3.05 | 3.10 | 3.14 | 3.19 | 3.23 | 3.28 | 3.32 | 3.37 | 3.41 | 3.46 | 3.51 | 3.55 
 
 ' 29.0 | 3.02 | 3.06 | 3.11 | 3.16 | 3.21 | 3.25 | 3.30 | 3.35 | 3.39 | 3.44 | 3.49 | 3.54 | 3.58 | 3.63 | 3.68 
 30.0 | 3.12 | 3.17 | 3.22 | 3.27 | 3.32 | 3.36 | 3.41 | 3.46 | 3.51 | 3.56 | 3.61 | 3.66 | 3.71 | 3.75 | 3.80 
 31.0 | 3.22 | 3.27 | 3.32 | 3.37 | 3.43 | 3.48 | 3.53 | 3.58 | 3.63 | 3.68 | 3.73 | 3.78 | 3.83 | 3.88 | 3.93 
 32.0 | 3.33 | 3.38 | 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.69 | 3.74 | 3.79 | 3.85 | 3.90 | 3.95 | 4.00 | 4.05 
 33.0 | 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.70 | 3.75 | 3.81 | 3.86 | 3.91 | 3.97 | 4.02 | 4.07 | 4.13 | 418 
 
 1 These corrections apply to a mercurial barometer with brass scale. They can, however, be used for a 
 mercurial barometer with glass scale, since the errors introduced thereby are negligible as applied to the 
 work contemplated in this circular. For exact correction to be applied to such a barometer, see Smith- 
 sonian Physical Tables, p. 119; 1914. An aneroid barometer should not be relied on. 
 
 For barometer readings below 640 mm the correction can be interpolated, since the difference, at any 
 particular temperature, for each 10 mm variation in barometer reading is practically constant. 
 
 3 Landolt-Boérnstein Physikalisch-Chemische Tabellen, Ed. 4, Table 127, p. 435. 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 If the barometer reading corrected to 0° C. is above 760 mm, 
 subtract the temperature correction from the observed thermometer 
 reading to determine the initial distilling point, and continue distilla- 
 tion to 170.0° C. plus the correction to determine the perouninae 
 distilling below 170.0° C. 
 
 (g) PonyMERIZzATION.—Place 20 ce of 38 N (equivalent to 100. 92 
 per cent H,SO,) sulphuric acid in a graduated narrow-necked Babcock 
 flask, stopper, and place in ice water to cool. Add slowly, from a 
 pipette, 5 cc of the turpentine to be exammed. Gradually mix the 
 contents, keeping warm, but being very careful that the temperature 
 does not rise above 60° C. When the mixture no longer warms up on 
 shaking, agitate thoroughly and place the flask in a water bath and 
 heat at 60 to 65° C. for not less than 10 minutes, keeping the contents 
 of the flask thoroughly mixed by vigorous shaking for one-half 
 minute each time, six times during the period. Do not stopper the 
 flask after the turpentine has been added, as itmay explode. Cool to 
 room temperature, fill the flask with concentrated sulphuric ‘acid 
 until the unpolymerized oil rises into the eraduated neck and centri- 
 fuge from 4 to 5 minutes at not less than’1,200 r. p. 'm., or’ for’ 15 
 “minutes at 900 r. p. m., or allow to stand, lightly stoppered, ‘for 12 
 hours. Calculate the pettGhithee? note the consistency’ and’ color, 
 and determine the refractive index (at 20° C. ) of tite unpolymerized 
 residue. 
 
 Reagent for testing.—In a weighed, glass-stoppered bottle (the 
 regular 214-liter acid bottle is of a convenient size) mix ordinary 
 concentrated sulphuric acid (sp. gr. 1.84) with fuming sulphuric acid. 
 If the fuming acid used contains 50 per cent excess SO;, the’ ratio 
 of one part, by weight, of the former. to three-fourths of apart; by 
 weight, of the latter will give a mixture slightly stronger than the 
 required strength. To determine the exact strength of this mixture 
 in terms of H,SO,, weigh exactly, in a weigh toes pipette of about 
 10 ce capacity, approximately 20 g of the acid. ° ‘ Allow it to flow down 
 the sides of the neck into a'1,000 cc volumetric flask contaming about 
 200 ce of distilled water. When the pipette has drained, wash all 
 traces of the acid remaining in the pipette into the’ flask, taking 
 precautions to prevent loss of SO;, and make up to the mark. -Titrate 
 20 ce portions, drawn from a burette, against half normal | alkali. 
 Calculate the concentration in terms of the aria et hig iSO, 
 in the sample taken. 
 
 In the same way determine the percentage of HS, i in aN stock of 
 ordinary concentrated acid (sp. gr. 1.84). From these data calculate 
 the quantity of the latter which must be added to the quantity of 
 mixed acid in the weighed bottle to bring it to a a 
 terms of H,SOQO,, of 100.92. per cent. 2 alee : 
 
SPECIFICATION FOR TURPENTINE 9 
 
 4 After adjusting the concentration by the addition of the ordinary 
 sulphuric acid, thoroughly shake the bottle of mixed acid and again 
 determine its concentration. The allowable variation is +0.05 per 
 
 » cent H,SO, Finally, as a check run a polymerization test on gum 
 turpentine known to be pure. The residue should fall below 2 per 
 cent. 
 
 Special precautions must be taken to piey eat dilution of this acid. 
 by the absorption of atmospheric moisture. The arrangement shown 
 in Figure 2 is most suitable for storing 
 and delivering measured quantities of 
 this reagent. 
 
 With the three-way stopcocks A and 
 B in the position shown, acid is siphoned 
 into the pipette P, the displaced air 
 passing into &. To empty the pipette, 
 A and B are turned to the position 
 shown by the broken lines, air passing 
 in ata. The acid adhering to the walls 
 of the pipette dries this air so that when 
 it passes into R on again filling the 
 pipette there is no accumulation of 
 moisture in the acid remaining in the 
 reservoir. If such arrangement is not to 
 be had, the acid should be kept in well- 
 fitting glass-stoppered bottles of not more 
 than one-half liter capacity. 
 
 Nts a aes MN PLM PRUE MRE MIME Tey Mater) Se AE Tae PUG, ON MEMS, oe MMR UeY ee et AAS 
 Daedlhah  oe nei | ie ial — ees ome i ag abe ae oe ‘ ? = oe ee + r . y 7 
 
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 4. BASIS OF PURCHASE 
 
 (a) Unrr.—Turpentine shall be pur- 
 : chased (a) by volume, the unit being a 
 * gallon of 231 cubic inches at 15.5° C. 
 4 (60° F.), or (6) by weight. A gallon of 
 turpentine at 15.5° C. (60° F.) weighs 
 7.19 to 7.30 pounds. The exact weight 
 in pounds per gallon of any sample can Fig. 2.—Acid bottle and pipetie 
 
 be determined by multiplying the specific 
 
 gravity at 15.5/15.5° C. (60/60° F.) by 8.33. Example: If the specific 
 gravity at 15.5° C. is 0.8642, the weight per gallon at this tempera- 
 ture will be 0.8642 X 8.33 =7.199 pounds. 
 
 When purchased by weight, quotations shall be by the pound or 
 by the 100 pounds. The request for bids will state whether quota- 
 tions shall be by the gallon, pound, or 100 pounds. 
 
 (6) Correction or VoLtumME.—The gallonage paid for shall be the 
 volume corrected to a standard temperature of 15.5° C. (60° F.). 
 
 ee, 
 
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 phn ete 
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10 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 The correction shall be deducted from (when the temperature of 
 gauging is above 15.5° C.) or added to (when the temperature of 
 gauging is below 15.5° C.) the gallonage as gauged. Such deduction 
 or addition shall be computed on the basis of a coefficient of expan- 
 sion for turpentine of 0.000945 per degree centigrade (or 0.000525 
 per degree Fahrenheit). -Example: If the temperature at which the 
 turpentine is gauged is 75° F. and the volume delivered (at that 
 temperature) is 8,000 gallons, then 0.000525 x 15° 8,000 gallons 
 equals the quantity in gallons which must be subtracted from 8,000 
 gallons to give the true gallonage at 60° F., or if the temperature at 
 which the turpentine is gauged is 10° C., then 0.000945 x 5.5° X 8,000 
 gallons equals the quantity in gallons which must be added to the 
 gauged volume of 8,000 gallons to give the true gallonage at 15.5° O. 
 
 (c) Certirication.—Turpentine delivered in. barrels, drums, or 
 tank cars shall either be accompanied by an official gauger’s certifi- 
 cate showing the net contents of each container and also the tem- 
 perature of contents at time of gauging, or shall be subject to gauging 
 by the purchaser’s inspector. In the absence of a statement of the 
 temperature at the time of gauging on the official gauger’s certifi- 
 cate, or in case the barrels show evidence of loss by leakage or other 
 shortage, the delivery shall be subject to Beco and | Tegauging 
 by the purchaser’s. inspector. 
 
 VII. PACKING AND MARKING 
 
 Packing shall be in accordance with commercial practice, unless 
 otherwise specified. | 
 VIII. NOTES 
 
 This sphcification does not cover what is norm as destructively 
 distilled wood turpentine. | 
 
 ADDITIONAL OOPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 & CENTS PER COPY 
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DEPARTMENT OF COMMERCE. 
 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 No. 87. 
 
 [2d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 ZINC OXIDE, DRY AND PASTE. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION No. 8. 
 
 This Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 Page 
 Aa a ie be Te Maar ae SiO rr oe ete ae aie cn OE ater hs Petes I 
 TREN 00g Ce eras iis otle vw ls nicks s DLs « he hale Bale: oo Oe eee ae 2 
 3. Laboratory examination of dry pigment... ....... 0... c eee eee eee beens 3 
 A iavorsiory examination of paste. .°... 2.0)... mi eieiug «myels ey veers deere 4 
 i ee een tsk oa a 0G Bees he tk ng se oOo es «x Se od 7 
 
 1. GENERAL. 
 
 : Zinc oxide may be ordered in the form of dry pigment or paste 
 
 ground in linseed oil. Purchases shall be made on the basis of 
 net weight. 
 
 The pigment may be American process zinc oxide, made direct 
 from the ore, or French process zinc oxide, made from spelter. 
 The contract shall state which kind is desired. 
 
 The color and color strength when specified shall be equal to 
 
 samples mutually agreed upon by buyer and seller. 
 
 109842°—22 
 
2 Circular of the Bureau of Standards 
 
 The pigment shall meet the following requirements: 
 
 Maximum.|! Minimum. 
 
 ’ Per cent. | Per cent. 
 Coarse particles retained on Standard No. 325 SCreeM...............seseeeerenes Li MD ick eee 
 
 Amerlcan process. _ French process. 
 
 Maximum.| Minimum. | Maximum.| Minimum, 
 
 Per cent. | Percent. | Percent. | Per cent. 
 
 PAO NORIO 25 5 5h os Sls ook os Sma oh ee ok ee ee om a een aa ene bo ae eee a 
 PP otal ALOR oe fscxs heer ks yee 5 Pass Aes uae ite tae OZ cea Out aes caiman ta 
 Total impurities, including moistute=. uc). 174 STs 2D, sot ay SEER , 1s To oy hee 
 
 The paste shall be made by thoroughly grinding the above 
 pigment with pure raw or refined linseed oil. The paste shall 
 not cake in the container and shall break up readily in cu to 
 form a smooth paint of brushing ogee * ae te 
 
 The paste shall consist of: 
 
 : ‘Maximum. Minimum, 
 
 Pigment. 00.26.85. eyed ee emeg ees cine cree Leahey — ee oye temntiice 
 TinSCOG, Cll... uss cc ws tis a etks div ns bts ok ase ele athe’ wictrolw ave 2Scaw shes (ay ole ecieain aine en ne 
 Coarse particles. and ‘‘skins”’ (total residue leit on No. 325 screen based, on pigitent) Ot 
 
 Woisture and other volatile miatter. ee TA. Tce nec e nae s cee ne emen ae ee |S hem 
 
 Norte.—Deliveries will, in general, be sampled and tested by the following methods, but the ‘sia 
 reserves the right to use any additional available information to ascertain whether the material meets the 
 specification. 
 
 2. SAMPLING. 
 
 - It is mutually agreed by buyer and seller that a single package 
 out of each lot of not. more than 1,000 packages shall be taken as 
 representative of the whole. AICTE 
 
 With the dry pigment, this package is to be opened by ees in- 
 spector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. When 
 requested, a duplicate sample may be taken from the same pack- 
 age and delivered to the seller, and the inspector sh take a cod 
 sample to hold for test. in case of dispute. ihe 
 
 With the paste, whenever possible, an original nope Re 
 tainer shall be sent to the laboratory; and when this is for any 
 Treason not done, the inspector shall determine by thoroughly’ test- 
 
 ing with a paddle or spatula whether the material meets the 
 requirement regarding not caking in the container. (See 4 “(a).) 
 After assuring himself that the paste is not caked ii tHe — ‘the 
 
ee eae eae eer a eee gOS ee 
 bagi » * > o_o. 
 
 Specification for Zinc Oxide, Dry and Paste 3 
 
 inspector jshall draw a sample of not Jess than 5 pounds of the 
 thoroughly mixed paste, place it in a clean, dry metal or glass 
 container which must be filled with the sample, closed with a tight 
 cover, sealed, marked, and sent to the laboratory for test with the 
 imspector’s report on caking in container. 
 
 3. LABORATORY EXAMINATION OF DRY PIGMENT. 
 
 (a) Coror.—Take 5 ¢ of the sample, add 1.5 cc of linseed oil, 
 
 tub up on a stone slab or glass plate with a flat-bottomed glass or 
 “stone pestle or muller to a uniform smooth paste. ‘Treat in ‘a 
 
 similar manner 5 g of the standard zinc oxide. Spread the two 
 pastes side by side on a clear colorless glass plate and compare the 
 
 colors. Ifthe sample is as white as or whiter than the “‘ standard,” 
 it passes this test. If the ‘‘standard”’ is whiter than the sample, 
 
 the material does not meet the specification. 
 (6) Color STRENGTH.—Weigh accurately 0.01 ¢ of lampblack, 
 
 place on a large glass plate or stone slab, add o.2 cc of linseed oil 
 
 and rub up with a flat-bottomed glass pestle or muller, than add 
 exactly 10 g of the sample and 2.5 cc of linseed oil, and grind with 
 a circular motion of the muller 50 times; gather up with a sharp- 
 edged spatula and grind owt twice more in a like manner, giving 
 the pestle a uniform pressure. ‘Treat another 0.01 g of the same 
 lampblack in the same manner except. that 1o g of standard zinc 
 oxide is used instead of the 10 g of the sample. Spread the two 
 
 pastes side by side on a glass microscope slide and compare the 
 
 colors. If the sample is as light as or lighter in color than the 
 “standard,” it passes this test. If the “standard” is lighter in 
 color than the sample, the material does not meet the specification. 
 
 (c) COARSE PARTICLES..—Dry in an oven at 105 to 110° C. a 
 325 screen, cool and weigh accurately. Weigh 10 g of the sample; 
 dry at 100° C., transfer to a mortar, add 100 cc kerosene, thor- 
 
 oughly mix by gentle pressure with a pestle to break up all lumps, 
 ‘wash with kerosene through the screen, breaking up all lumps, 
 
 but not grinding. After washing with kerosene until all but the 
 particles which are too coarse to pass the screen have been washed 
 through, wash all kerosene from the screen with ether or petro- 
 
 leum ether, heat the screen for one hour at 105 to 110° C., cool and 
 
 weigh. | 
 
 1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 
 
 ‘see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
 the United States. 
 
4 Circular of the Bureau of Standards 
 
 (d) QUALITATIVE ANALYsIS.—Test for matter insoluble in hy- 
 drochlorie acid, for lead, calcium, etc., by regular sic i of 
 qualitative analysis. 
 
 (e) Zinc OxipE.—With samples free from iiptaritiel ca (d)), 
 ignite a weighed sample and calculate the residue as ZnO. With 
 samples containing impurity, proceed as follows: Weigh accu- . 
 rately about 0.25 g, transfer to a 400 cc beaker, moisten with 
 alcohol, dissolve in 10 cc of hydrochloric acid and 20cc of water 
 and titrate with standard potassium ferrocyanide, following the 
 procedure used in standardizing this reagent. _ (See 5(2).) 
 
 (7) Tora, SuLPpHUR,—Weigh accurately about 10 g of the 
 sample. Moisten with afew drops of alcohol, add 5 ce of bromine 
 water (saturated solution of bromine), then concentrated hydro- 
 chloric acid in excess, boil to expel bromine, and dilute to about 
 roo cc. (Material complying with the specification should all go 
 into solution; if insoluble matter remains, filter and examine by 
 appropriate methods.) Make alkaline with ammonia, then just 
 acid with hydrochloric acid, heat to boiling and add about 10 cc 
 of hot barium chloride solution. (See Reagents.) Let stand 
 several hours (overnight), filter on a weighed Gooch crucible, 
 wash thoroughly with hot water, dry, ignite, cool, and nests the 
 BaSO,. Calculate to S (BaSO, x 0.1373 =S). ae 
 
 4. LABORATORY EXAMINATION OF PASTE. 
 
 (2) CAKING IN CONTAINER.—When an original package is re- 
 ceived in the laboratory, it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paste must be no more difficult . 
 to break up and show no more caking than a normal good grade 
 of zinc oxide paste. The paste shall be finally thoroughly mixed, 
 removed from the container, the container wiped clean, and 
 weighed, This weight subtracted from the weight of the original 
 package gives the net weight of the contents. A portion of the 
 thoroughly mixed paste shall be placed in a clean container and 
 the portions for the remaining tests promptly weighed out. 
 
 (0) Mrxinc witH LINSEED Or.—One hundred grams of eid 
 paste shall be placed in a cup, 35 cc of linseed oil added slowly 
 with careful stirring and mixing with a spatula or paddle. The 
 resulting mixture must be smooth and of good beasts con- 
 sistency. 
 
 (c) MoIstTURE AND OTHER VOLATILE MATTER. te accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
 about 8 cm in diameter, spreading the paste over the bottom. 
 
RIS 
 
 et tt ca aie eae Sick co Se ade aa 
 
 Specification for Zinc Oxide, Dry and Paste 5 
 
 Heat at 105 to 110° C. for three hours, cool, and weigh. Calculate 
 loss in weight as percentage moisture and other volatile matter. 
 
 (d) Per Cent PicmMent.—Weigh accurately about 15 g of the 
 paste into a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
 traction mixture’? (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add > 
 sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm with 
 a similar tube or a tube with water. Whirl at a moderate speed 
 until clear. Decant the clear supernatant liquid. Repeat the 
 extraction twice with 40 cc portions of extraction mixture, and 
 once with 40 cc of ether. After drawing off the ether, set the 
 tube in a beaker of water at about 80° C. or on top of a warm 
 oven for 10 minutes, then in an oven at 105 to 110° C. for 2 hours. 
 Cool, weigh, and calculate percentage of pigment. 
 
 (ec) EXAMINATION OF PiGMENT.—Grind the pigment from (d) 
 to a fine powder, pass through a No. 80 screen to remove any 
 ‘‘skins,”’ preserve in a stoppered tube and apply tests 3 (d), (¢), 
 and (f). If required, apply tests 3 (a) and (b) in.comparison with 
 a portion of pigment extracted from the standard paste in enaehy 
 the same manner as in extracting the sample. 
 
 _(f) PREPARATION OF Farry Acips.—To about 25 g of the paste 
 in a porcelain casserole add 15 cc aqueous sodium hydroxide (see 
 Reagents), and 75 cc of ethyl alcohol, mix and heat uncovered on 
 a steam bath until saponification is complete (about one hour). 
 Add. 100. ce water, boil, add sulphuric acid of specific gravity 
 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
 funnel to which some water has been previously added. Draw 
 off as much as possible of the acid aqueous layer, wash once 
 with water; then add 50 cc of water and 50 cc of ether. Shake 
 very gently with a whirling motion to) dissolve the fatty acids 
 in the ether, but not violently, so as to avoid forming an 
 emulsion. Draw off the aqueous layer and wash the ether layer 
 with one 15 cc portion of water and then with 5 cc portions of 
 water until free from sulphuric acid. Then draw off completely 
 the water layer. Transfer the ether solution to a dry flask, and 
 add 25 to 50g of anhydrous sodium sulphate. Stopper the flask 
 and let, stand with occasional shaking at a, temperature below 25° 
 C. until,the water is completely removed from the ether solution, 
 which will be shown by the solution becoming perfectly clear 
 
6 Circular of the Bureau of Standards» 
 
 above the solid sodium sulphate. Decant this clear solution (i 
 necessary through a dry filter paper) into a dry 100 ce’ Erlenmeyer 
 flask. Passa rapid current of dry air (pass through CaCl, tower) 
 into the mouth of the Erlenmeyer flask and heat to a temperature 
 below 75°C. on a dry hot plate until the either is entirely driven off. 
 
 Norte.—It is important to follow all of the details, since ether generally contains 
 alcohol and after washing with water always contains water. It is very difficult 
 to remove water and alcohol by evaporation from fatty acids, but.the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes both 
 
 water and alcohol. Ether, in the absence of water and alcohol, is aoa removed 
 from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should ba kept ina stoppeted 
 flask and examined at once. 
 
 (g) TEST FoR MINERAL Ol AND OTHER Unkasonnaialien ie 
 TER.—Place ro drops of the fatty acid’ (f) in a 50 ¢e test tube, 
 add 5 cc of alcoholic soda (see Reagents); boil vigorously for 5 
 minutes, add 40 ce of water, and mix; a clear solution indicates 
 that not more than traces of unsaponifiable matter are present. 
 If the solution is not clear, the oil is not pure linséed oil. 
 
 (h) IoprIne NuMBER oF Farry Actps.—Place’a small quantity 
 of the fatty acids (f) in a small weighing burette or beaker. 
 Weigh accurately. Transfer by dropping about 0:15 g (0.10 to 
 0.20 g) toa 500 cc bottle having a well-ground glass stopper, or 
 an Erlenmeyer flask having a specially flanged neck for the iodine 
 test. Reweigh the burette or beaker and determine the amount 
 of sample used. Add 10 cc of chloroform. Whirl the bottle to 
 dissolve the sample. Add 10 cc of chloroform to two empty 
 bottles like that used for the sample. Add to each bottle 25 cc of 
 the Hanus solution (see Reagents) and let stand, with occasional 
 shaking, for one-half hour. Add 10 ce of thé 15 per cent potas- 
 stum-iodide solution and 100 cc of water, and titrate with standard 
 sodium thiosulphate, using starch as indicator. The titrations on 
 the two blank tests should agree within 0.1 cc. ' From the differ- 
 ence between the average of the blank titrations and the titration 
 on-the sample and the iodine value of the thiosulphate solution, 
 calculate the iodine number of the sample tested. (Iodine 
 number is centigrams of iodine to 1 g of sample.) If the iodine 
 number is less than 170, the oil does not meet the specification. 
 
 (7) CoaRSE PARTICLES AND ‘‘SKINS.”—Weigh an”amount of 
 paste containing 10 g of pigment (see 4 (d)), add kerosene, and 
 wash through a No. 325 screen asin 3 (c). The residue is reported 
 as ‘“Coarse particles and skins.” : : 2 tal aw 
 
PREG Oe eh See eC EE EME IETS nyt FE Eee S| SERIE en ee 
 
 Spectfication for Zinc Oxide, Dry and Paste y 
 5. REAGENTS. 
 
 (a) EXTRACTION MIxTURE.— 
 
 - 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl]! alcohol. 
 I volume acetone. 
 
 (6) AguEous Sopium HyproxipE.—Dissolve 100 g sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 
 (c) STANDARD SopiumM ‘THIOSULPHATE SOLUTION.—Dissolve 
 pure sodium thiosulphate in distilled water that has been well 
 boiled to free it from carbon dioxide, in the proportion of 24.83 g 
 crystallized soditim thiosulphate to 1,000 cc of the solution. It is 
 best to let this solution stand for about two weeks before stand- 
 ardizing. Standardize with pure resublimed iodine. (See Ana- 
 lytical Chemistry, Treadwell-Hall, vol. 11, 3d ed., p. 646.) This 
 solution will be approximately decinormal, and it is best to leave 
 it as it is after determining its exact iodine value rather than to 
 attempt to adjust it to exactly decinormal. Preserve in a stock 
 bottle provided with a guard tube filled with soda lime. 
 
 (dy SvarCu SoLution.—Stir up 2 to 3 g of potato starch or 
 5 g soluble Starch with too cc of'1 per cent salicylic acid solution, 
 add- 300 to 400 cc boiling water, and boil the mixture until the 
 starch is practically dissolved, then dilute to 1 liter. 
 
 (e) Potassium IopIpDE SoLuTION.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 cc. 
 
 (f) Hanus SoLutTIon.—Dissolve 13.2 g of iodine in 1,000 ce 
 of 99.5 per cent glacial acetic acid which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, 
 determined by titration (3 cc of bromine is about the proper 
 amount). The iodine may be dissolved by the aid of heat, but 
 the solution should be cold when the bromine is added. 
 
 (g) ALCOHOLIC SoDIUM HYDROXIDE SOLUTION.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
 Decant the clear liquid into another bottle and keep weil stop- 
 pered. ‘This solution should be colorless or only slightly yellow 
 when used, and it will keep colorless longer if the alcohol is pre- 
 viously treated with sodium hydroxide (about 80 g to 1,000 cc), 
 kept at about 50° C. for 15 days and then distilled. 
 
8 Circular of the Bureau of Standards 
 
 (h) URANYL INDICATOR FOR Zinc TiTRaTION.—A 5 per cent 
 solution of uranyl nitrate in water or a 5 per.cent. solution, of 
 uranyl acetate in water made slightly acid; with acetic acid. 
 
 (2) STANDARD PoTassIuM FERROCYANIDE.—Dissolve 22 g of 
 the pure salt in water and dilute to 1,000 cc. To standardize 
 transfer about 0.2 g (accurately weighed) of pure metallic zinc 
 or freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
 10 cc hydrochloric acid and 20 ce water... Drop in a :small piece 
 of litmus paper, add ammonium hydroxide until slightly alkaline, 
 then add hydrochloric acid until just acid, and then add 3 cc 
 strong hydrochloric acid. Dilute to about 250 cc with hot water 
 and heat nearly to boiling. Run in the ferrocyanide solution 
 slowly from a burette with constant stirring until a drop tested 
 on a white porcelain plate with a drop of the uranyl indicator 
 shows a brown tinge after standing one minute. A blank should 
 be run with the same amounts of reagents and water as in the 
 standardization. The amount of ferrocyanide solution required 
 for the blank should be subtracted from the amounts used in 
 standardization and in titration of the sample. The standardiza- 
 tion must be made under the same conditions of temperature, 
 volume, and acidity as obtain when the sample is titrated, _ 
 
 (7) Bartum CHLORIDE SOLUTION.—Dissolve 100 g of pure crys- 
 tallized barium chloride in water and dilute to 1,000 cc. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 HE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 5 CENTS PER COPY ; ; L f4) 
 v ort ampngsl 
 
 WASHINGTON : GOVERNMENT PRINTING OFFICE : fo22 
 
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 See A eT ee Le eT oe Ta RS. ery IS Oe Pe a 
 
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 od 
 
 DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 No. 88. 
 
 [2d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION F OR 
 LEADED ZINC OXIDE, DRY AND PASTE. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 9. 
 
 This Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the Departments and Independent Fstablish- 
 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 
 Page, 
 ag ED a lab ten ai olay en As Ya eae I 
 MME CR Riayat 2) oe Akay Jk ve Soeut,. tk Se Reps 2 
 3- Laboratory examination of mig cht tah ae Sa ee Rem cate» i, Ae optic NR Sie 3 
 ee -Leboratory examination of paste. 2.6 U0. 2 JOR. I Jo) Ae 4 
 RE oi yas ao, nee s's a a PalghQalos AEE. Bh sshd whee 7 
 
 1. GENERAL. 
 
 Leaded zine oxide, frequently known as leaded zinc, consists 
 of zinc oxide and varying amounts of lead compounds. It may 
 be ordered in the form of dry pigment or paste ground in linseed 
 oil. Purchases shall be made on the basis of net weight. 
 
 The pigment may be high-leaded zinc oxide or low-leaded zinc 
 oxide. The contract shall state which kind is desired. The color 
 and color strength when specified shall be equal to samples mutu- 
 ally agreed upon by buyer and seller. 
 
 106489°—24 
 
2 Circular of the Bureau of Standards 
 
 The pigment shall meet the following requirements: 
 
 Maximum.) Minimum, 
 
 Per cent. | Percent. 
 Coarse particles retained on Standard No. 325 screen .........--.-----+-+---++++-- LO hice kee ey 
 
 High-leaded. Low-leaded. 
 
 Maximum. | Minimum. | Maximum. | Minimum. 
 
 | ee | 
 
 Percent. | Percent. | Percent. | Per sage 
 
 Zinc oride (ZnO) .. noes eB Ge sed be Saeco Sn ers «<a Te es eee 
 Water soluble salts: -..25c. so 28s ee st ackk caeaerenens 1:04. capeeia see 5 TE De 
 Total impurities, including moisture.....-....-.----.--- 255 12s Ane 1 Bite sh ce toes 
 
 The balance to be normal or basic lead sulphate. 
 
 The paste shall be made by thoroughly grinding the above pig- 
 ment with pure raw or refined linseed oil. The paste shall not 
 cake in the container and shall break up readily in oil to form a 
 smooth paint of brushing consistency. The paste shall consist of: 
 
 Maximum.| Minimum, 
 
 Per ee Per cent. 
 
 Pigment... . slab snccsec ces ns Senin 0 cid senpecincwmssis dens ah ose ckedse dees see eh mak] ¢ eg GmeM naan eae avis 
 Tilnseed Ole eo or re se esc case pees te mens opin mine eet <ln nals = mieie eae see 12.0 
 Moisture and other volatile matter... ......-..- +2. ses eee eee ee eee ee eee eter wees OS tan passa. a» 
 Coarse particles and “‘skins” (total residue left on No. 325 screen based on pigment) Cp ee Pet eS 
 
 Notr.—Deliveries will, in general, be sampled and tested by the following methods, but the pur- 
 chaser reserves the right to use any additional available information to ascertain whether the material 
 meets the specification. 
 
 2, SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. 
 
 With the dry pigment, the package is to be opened be the in- | 
 
 spector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. 
 
 With the paste, whenever possible, an original unopened con- 
 tainer shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine, by thorough 
 testing with a paddle or spatula, whether the material meets the 
 requirement regarding not caking in the container. (See 4 (a) 
 After assuring himself that the paste is not caked in the con- 
 tainer, the inspector shall draw a sample of not less than 5 pounds 
 of the thoroughly mixed paste, place it in a clean dry metal or 
 glass container, which must be filled with the sample, closed with 
 
 P 
 
Specification for Leaded Zinc Oxide, Dry and Paste zB 
 
 a tight cover, sealed, marked, and sent to the laboratory for test 
 with the inspector’s report on caking in container. 
 
 When requested, a duplicate sample may be taken from the 
 saine package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 3. LABORATORY EXAMINATION OF DRY PIGMENT. 
 
 (a) CoLror.—Take 5 g of the sample, add 1.5 cc of linseed oil, 
 rub up on a stone slab or glass plate with a flat-bottomed glass 
 or stone pestle or muller to a uniform smooth paste. Treat in 
 a similar manner 5 g of the standard leaded zinc oxide: Spread 
 the two pastes side by side on a clear colorless glass plate and 
 compare the colors. If the sample is as white or whiter than the ~ 
 ‘“‘standard,’’ it passes this test. If the ‘standard’ is whiter 
 than the sample, the material does not meet the specification. 
 
 (b) CoLoR STRENGTH.—Weigh accurately 0.01 g of lampblack, 
 place on a large glass plate or stone slab, add 0.2 cc of linseed oil, 
 and rub up with a flat-bottomed glass pestle or muller; then add 
 exactly 10 g of the sample and 2.5 cc of linseed oil, and grind 
 with a circular motion of the muller 50 times; gather up with a 
 sharp-edged spatula and grind out twice more in a like manner, 
 giving the pestle a uniform pressure. Treat another 0.01 g of 
 the same lampblack in the same manner, except that 10 g of 
 standard leaded zinc oxide is used instead of the 10 g of the sam- 
 ple. Spread the two pastes side by side on a glass microscope 
 slide and compare the colors. If the sample is as light as or lighter 
 in color than the ‘‘standard,’’ it passes thistest. Ifthe ‘‘standard’”’ 
 is lighter in color than the sample, the material does not meet 
 the specification. 
 
 (c). Coarse ParTICLES.'—Dry in an oven at 105° to 110° C. 
 a 325 screen, cool and weigh accurately. Weigh 10 g of the 
 
 sample; dry at 100° C., transfer to a mortar, add 100 cc kero- 
 
 sene, thoroughly mix by gentle pressure with a pestle to break up 
 all lumps, wash with kerosene through the screen, breaking up all 
 lumps, but not grinding. After washing with kerosene until all 
 but the particles which are too coarse to pass the screen have been 
 washed through, wash all kerosene from the screen with ether or 
 petroleum ether, heat the screen for one hour at 105° to EIQ ty: 
 cool and weigh. 
 
 1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 
 see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
 the U.S. 
 
4 Circular of the Bureau of Standards 
 
 (d) QUALITATIVE ANALyYsIs.—Test for matter insoluble in hydro- 
 chloric acid, lead, calcium, carbon dioxide, etc., by snips cbsooins 
 of qualitative analysis. 
 
 (ec) MotsturE.—Place 1 g of the sample in a wide-mouth short 
 weighing tube provided with a glass stopper. Heat badneiees. <0) 
 removed for two hours at a temperature between 105 and 110° C. 
 Insert stopper, cool, and weigh. Calculate loss in west as 
 moisture. 
 
 (f) WATER SOLUBLE SALTs.—To Io g of ipwiet ina $06 ce 
 volumetric flask, add 200 ce of water, boil for five minutes, 
 - nearly fill the flask with hot water, allow to cool, fill to mark, mix, 
 filter through a dry paper, discard the first 50 ce of filtrate, 
 transfer 100 cc of the filtrate (corresponding to 2 g of sample) 
 to a weighed dish, Rpatieein to dryness, heat for one hour in an 
 oven at 105 to 110° C., cool, and weigh, calculate to ais 
 of water soluble salts. 
 
 (9) Zinc Ox1pE.— Weigh accurately about 0.3 g of the pigment, 
 transfer to a 400 cc beaker, add 30 ce of hydrochloric acid 
 (1 :2), boil for two or three minutes, add 200 ce of water and 
 a small piece of litmus paper; add ammonium hydroxide until 
 slightly alkaline, render just acid with hydrochloric acid, then add 
 3 cc of strong hydrochloric acid, heat nearly to boiling, and 
 titrate with standard potassium ferrocyanide as in standardizing 
 the solution. (See Reagents 5 (d).) Calculate total zine as ZnO. 
 
 (h) CaLCULATIONS.—If, as will be the case with material com- 
 plying with the specification, no metals but zine and lead are 
 found by qualitative tests, add the percentage of ZnO, moisture, 
 and water soluble salts and subtract the sum from 100. ee the 
 remainder ‘‘normal and basic lead sulphate.” 
 
 4, LABORATORY EXAMINATION OF PASTE. 
 
 (a) CAKING IN CONTAINER.—When an original package is re- 
 ceived in the laboratory, it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paste must be no more diffi- 
 cult to break up and show no more caking than a normal good 
 grade of leaded-zinc oxide paste. The paste shall be finally 
 thoroughly mixed, removed from the container, the container 
 wiped clean, and weighed. This weight subtracted from the 
 weight of the original package gives the net weight of the con- 
 tents. A portion of the thoroughly mixed paste shall be placed — 
 in a clean container and the portions for the remaining tests 
 promptly weighed out. 
 
Specification for Leaded Zinc Oxide, Dry and Paste 5 
 
 (b) MIXING WITH LINSEED O1L.—One hundred grams of the paste 
 shall be placed in a cup, 35 cc of linseed oil added slowly with 
 | careful stirring and mixing with a spatula or paddle, the resulting 
 
 ‘ mixture must be smooth and of good brushing consistency. 
 
 (c) MoistuRE AND OTHER VOLATILE MatTrer.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish » 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heat at 105 to 110° C. for three hours, cool, and weigh. Calculate 
 
 : loss in weight as percentage of moisture and other volatile matter. 
 
 : (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
 
 -of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
 
 ‘“‘extraction mixture’’ (see Reagents), mix thoroughly with a glass 
 
 rod, wash the rod with more of the extraction mixture, add. suffi- 
 
 cient of the reagent to make a total of 60 cc in the tube. Place 
 the tube in the container of a centrifuge, surround with water, 
 
 and counterbalance the container of the opposite arm with a 
 
 similar tube or a tube with water. Whirl at a moderate speed 
 
 until clear. Decant the clear supernatant liquid. Repeat the 
 extraction twice with 4o cc of extraction mixture, and once with 
 
 4o ce of ether. After drawing off the ether, set the tube in a 
 
 beaker of water at about 80° C. or on top of a warm oven for 10 
 
 : minutes, then in an oven at 105 to 110° C. for two hours. Cool, 
 
 weigh, and calculate percentage of pigment. 
 
 (ec) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
 to a fine powder, pass through a No. 80 screen to remove any 
 
 “skins,’’ preserve in a stoppered tube, and apply tests 3 (d), (/), 
 
 ia 
 
 : (g), and (kh). If required, apply tests 3 (a) and (b) in comparison 
 . _ with a portion of pigment extracted from the standard paste in 
 q exactly the same manner as in extracting the sample. 
 
 4 (f) PREPARATION oF Farry Acips.—To about 25 g of the 
 4 paste in a porcelain casserole, add 15 ce of aqueous sodium hy- 
 P droxide (see Reagents) and 75 ce of ethyl alcohol; mix, and heat 
 3 uncovered n a steam bath until saponification is complete (about 
 4 one hour). Add 100 cc of water, boil, add sulphuric acid of 
 . specific gravity 1.2 (8 to 10 cc in excess); boil, stir, and trans- 
 4 fer to a separatory funnel, to which some water has been pre- 
 q viously added. Draw off as much as possible of the acid aqueous 
 4 layer and lead sulphate precipitate, wash once with water, then 
 at add 50 cc of water and 50 cc of ether. Shake very gently with 
 2 a whirling motion to dissolve the fatty acids in the ether, but 
 . not violently, so as to avoid forming an emulsion. Draw off the 
 
6 Circular of the Bureau of Standards 
 
 aqueous layer and wash the ether layer with one 15 ce portion of 
 water and then with 5 cc portions of water until free from sul- 
 phuric acid. Then draw off completely the water layer. Transfer 
 the ether solution to a dry flask, add 25 to 50 g. of anhydrous 
 sodium sulphate. Stopper the flask and let stand with occa- 
 sional shaking at a temperature below 25° C. until the water is 
 completely removed from the ether solution, which will be shown 
 by the solution becoming perfectly clear above the solid sodium 
 sulphate. Decant this clear solution (if necessary, through a dry 
 filter paper) into a dry 100 ce Erlenmeyer flask. Pass a rapid 
 current of dry air (pass through CaCl, tower) into the mouth of the 
 Erlenmeyer flask and heat to a temperature below aa i on a dry 
 hot plate until the ether is entirely driven off. 
 
 NoTE.—It is important to follow all of the details, since ether generally contains 
 
 alcohol and after washing with water always contains water. It is very difficult 
 to remove water and alcohol by evaporation from fatty acids, but the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes both 
 water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
 from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (g) TEST FOR MINERAL OIL AND OTHER UNSAPONIFIABLE MAT- 
 TER.—Place ro drops of the fatty acid (/) in a 50 ce test tube, add 
 5 cc of alcoholic soda (see Reagents), boil vigorously for five 
 minutes, add 40 cc of water and mix; a clear solution indicates 
 that not more than traces of unsaponifiable matter are present. 
 If the solution is not clear, the oil is not pure linseed oil. 
 
 (h) IoDINE NUMBER OF Farry Acips.—Place a small quantity 
 of the fatty acids (f) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
 to a 500 cc bottle having a well-ground glass stopper or an Erlen- 
 meyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine the amount of sample 
 used. Add 1occof chloroform. Whirl the bottle to Gissolve the 
 sample. Add 1o cc of chloroform to two empty bottles like that 
 used for the sample. Add to each bottle 25 cc of the Hanus solu- 
 tion (see Reagents) and let stand with occasional shaking for one- 
 half hour. Add 10 cc of the 15 per cent potassium iodide solu- 
 tion and roo ce of water and titrate with standard sodium thio- 
 sulphate, using starch as indicator. ‘The titrations on the two 
 blank tests should agree within 0.1 ce. From the difference be- 
 tween the average of the blank titrations and the titration on the 
 
Specification for Leaded Zinc Oxide, Dry and Paste 7 
 
 sample and the iodine value of the thiosulphate solution calculate 
 the iodine number of the sample tested. (Iodine number is centi- 
 grams of iodine to 1 g of sample.) If the iodine number is less 
 than 170, the oil does not meet the specification. 
 
 (2) COARSE PARTICLES AND ‘‘SKINS.”’—Weigh an amount of 
 paste containing 10 g of pigment (see 4(d)), add 100 g of kerosene | 
 and wash through a No. 325 screen. ‘he residue is reported as 
 “coarse particles and ‘skins.’ ”’ 
 
 5. REAGENTS. 
 
 (a) URANyL INDICATOR FoR ZINC TITRATION.—A 5 per cent 
 solution of uranyl nitrate in water or a 5 per cent solution of 
 uranyl acetate in water made slightly acid with acetic acid. 
 
 (b) STANDARD POTASSIUM FERROCYANIDE.—Dissolve 22 g of 
 the pure salt in water and dilute to 1,000 cc. To standardize, 
 transfer about 0.2 g (accurately weighed) of pure metallic zine or 
 freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
 ro cc of hydrochloric acid and 20 cc of water. Drop in a small 
 piece of litmus paper, add ammonium hydroxide until slightly 
 alkaline, then add hydrochloric acid until just acid and then add 
 3 ce of strong hydrochloric acid. Dilute to about 250 cc with 
 hot water and heat nearly to boiling. Run in the ferrocyanide 
 solution slowly from a burette with constant stirring until a drop 
 tested on a white porcelain plate with a drop of the uranyl indi- 
 cator shows a brown tinge after standing one minute. A blank 
 should be run, using the same amounts of reagents and water as in 
 the standardization. The amount of ferrocyanide solution re- 
 quired for the blank should be subtracted from the amounts used 
 in standardization and in titration of the sample. The standardi- 
 zation must be made under the same conditions of temperature, 
 volume, and acidity as obtain when the sample is titrated. 
 
 (c) BARIUM CHLORIDE SOLUTION.—Dissolve 100 g of pure 
 crystallized barium chloride in water and dilute to 1,000 cc. 
 
 (d) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve pure 
 sodium thiosulphate in distilled water that has been well boiled 
 to free it from carbon dioxide, in the proportion of 24.83 g of 
 crystallized sodium thiosulphate to 1,000 cc of the solution. It 
 
 ‘is best to let this solution stand for about two weeks before stand- 
 
 ardizing. Standardize with pure resublimed iodine (See Ana- 
 lytical Chemistry, Treadwell-Hall, 2, 3d ed., p. 646). This solu- 
 tion will be approximately decinormal, and it is best to leave it as 
 
8 Circular of the Bureau of Standards 
 
 it is after determining its exact iodine value, rather than to 
 attempt to adjust it to exactly decinormal. Preserve in a stock 
 bottle provided with a guard tube filled with soda lime. 
 
 (e) STARCH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 g 
 of soluble starch with 100 ce of 1 per cent salicylic acid solution, 
 add 300 to 400 ce of boiling water, and boil the mixture until the 
 starch is practically dissolved, then dilute to 1 liter. | 
 
 (f) EXTRACTION MIxTURE.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 I volume acetone. 
 
 (9) AQUEOUS Sop1um HypRoxIDE.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 ce. 
 
 (h) Potassium IopIDE SoLUTION.—Dissolve 150 g of potassium 
 iodide free from iodate, in distilled water and dilute to 1,000 cc 
 
 (1) Hanus SOLUTION.—Dissolve 13.2 g of iodine in 1,000 cc of 
 99.5 per cent glacial acetic acid, which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, deter- 
 mined by titration (3 cc of bromine is about the proper amount). 
 The iodine may be dissolved by the aid of heat, but the ia wis 
 should be cold when the bromine is added. 
 
 (7) ALCOHOLIC SoDIUM HyDROXIDE SOLUTION.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
 Decant the clear liquid into another bottle, and keep well stop- 
 pered. ‘This solution should be colorless or only slightly yellow 
 when used, and it will keep colorless longer if the alcohol is pre- 
 viously treated with sodium hydroxide (about 80 g to 1,000 cc), 
 kept at about 50° C. for 15 days, and then distilled. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 5 CENTS PER COPY 
 
 . . 
 WASHINGTON : GOVERNMENT PRINTING OFFICH ! 1924 ; 
 
U. S. Gov't 
 Master 
 Specification 
 
 No. 10b 
 DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 89 
 
 [3d edition. Issued April 25, 1927] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 PAINT, WHITE, AND TINTED PAINTS MADE ON A WHITE 
 BASE, SEMIPASTE AND READY MIXED ° 
 
 FEDERAL SPECIFICATIONS BOARD, SPECIFICATION No. 10b 
 [Revised as of Sept. 2, 1925] 
 
 This specification was officially adopted by the Federal Specifications Board 
 on February 3, 1922, for the use of the departments and independent estab- 
 lishments of the Government in the purchase of white paint and tinted 
 paints made on a white base, semipaste and ready mixed. 
 
 [The date on which the technical requirements of this revision of this specification became manda- 
 tory for all departments and independent establishments ofthe Government was September 2, 1925. 
 The changes included in this revision were authorized by the Federal Specifications Board and 
 promulgated in a circular letter on above revision date.] 
 
 CONTENTS 
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 Oe Tet FR Piel OD OU ADE ule. Nel ie BO ee 3 
 eibomimete (60h iG ici suee worl). aie -68 - gidseey 3 
 Ss) Meadyemined paints sola ln - asym t pee bee -srra ee nT 3 
 VI. Methods for sampling and testing. --___----------------------- 4 
 MINS ENE hu! ciciiidg de sald ck op salah od Sal te be oo ee en 2 4 
 2. Laboratory examination—semipaste.___..-.------------- 4 
 OY Analysis’ of pigmentlit Oh cael eh a ek ea 7 
 4. Laboratory examination—mixed paint___...------------- 8 
 im Béagenta cece ssl) at ache eeoeeas - ond} -sabery- eS 9 
 VII. Packing and marking of shipments_-_.-------------------+----- 11 
 EES SOEUR RE: ice PRS SUPA Ren Cin SEs oe ee oy MOINES PRY MR ARAL 7 SP ee 11 
 
 a eee ee a en PD AO ea arn i So ee 
 
 1 It is believed that this specification admits practically all high-grade lead-zinc prepared paints generally 
 available in the United States, and which are therefore obtainable without requiring manufacturers to 
 make up special lots. On large contracts for which paint will be specially made, the purchaser may require 
 the bidder to submit the formula of the paint he proposes to furnish as conforming to the specifications. 
 
 43255°—27 
 
2 CIRCULAR ty THE BUREAU OF STANDARDS 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification. 
 II. TYPES 
 
 White paint and tinted paints made on a white base shall be of 
 the following types: Semipaste in linseed oil and ready-mixed. 
 
 Ill. MATERIAL AND WORKMANSHIP 
 See detail requirements. Be 
 IV. GENERAL REQUIREMENTS 
 See detail requirements. | 
 V. DETAIL REQUIREMENTS 
 1, PIGMENT 
 
 The pigment shall be composed of: 
 
 Maximum | Minimum 
 
 Per cent Per cent © 
 White lead (basic carbonate, basic sulphate, or a mixture thereof)..........--..- 70 45 
 
 Hing oxide (ZNO) ait cnvae saeweeve penta sedan =e snare ~neiapieiuntenan apendimatennien ears aes 55 30 
 White mineral pigments, containing no lead or zinc compounds, pure tinting 
 Colors, Or ANY MIXtUTe PHeCTEOL..-.~. 5. eos caste ccs noadedcetteane eth e ee see eee 15 
 
 In no case shall the sum of the basic lead carbonate, basic lead 
 sulphate, and zinc oxide be less than 85 per cent. The lead and 
 zinc pigments may be introduced in the form of any mixture pre- 
 ferred of basic carbonate white lead, basic sulphate white lead, zinc 
 oxide, or leaded zinc, provided the above requirements as to composi- 
 tion are met. The total lead dissolved by dilute acetic acid and hot 
 acid ammonium acetate, weighed as lead sulphate, and this weight 
 multiplied by the factor 0.883 shall be considered white lead. It is 
 not possible to determine the amount of lead carbonate and lead 
 sulphate when carbonates or sulphates of other metals, such as 
 calcium, are present. Also neither basic lead carbonate nor basic 
 lead sulphate are definite compounds. ‘The factor to convert PbSQ, 
 to (PbCO;), Pb(OH)s is 0.854, to convert PbSO, to PbSO,PbO is 
 0.868, and to convert PbSO, to (PbSQO,). PbO is 0.918. The arbitrary 
 factor used under this specification is the mean of the largest and 
 smallest of these three factors. aid 
 
SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 3 
 2. LIQUID 
 
 The liquid in semipaste paint shall be entirely linseed oil; in ready- 
 mixed paint it shall contain not less than 90 per cent linseed oil, 
 the balance to be combined drier and thinner. The thinner shall be 
 turpentine, volatile mineral spirits, or a mixture thereof. 
 
 3. SEMIPASTE 
 
 Semipaste shall be made by thoroughly grinding the pigment with 
 linseed oil. 
 
 The semipaste as received and three months thereafter shall be 
 not caked in the container and shall break up readily in linseed 
 oil to form a smooth paint of brushing consistency. It shall “mix 
 readily with linseed oil, turpentine, or volatile mineral ‘spirits, or 
 any combination of these substances, in all proportions without 
 curdling. ‘The color and hiding power when specified shall be equal 
 to that of a sample mutually agreed upon by buyer and seller. The 
 weight per gallon shall be not less than 19.0 pounds. The paste shall 
 consist of: | 
 
 Maximum | Minimum 
 
 Per cent Per. cent 
 77 73 
 
 SSS EGS SUE en p-chadlbe: barnegat Ml: Site. able Ah Ahh pe i sedte shade’ 
 oe 5 a Re RTS INS Ce aS ai a a ee BEES De OREN AES 27 23 
 Moisture and otherwolatilempatter. . noe cso Sse asd eee 9 ek ek aS hk MAE eo Se 
 Coarse particles and “skins’’ (total residue retained on No. 325 screen based on 
 
 I pA i cee ne ees 
 
 4. READY-MIXED PAINT 
 
 Ready-mixed paints shall be well ground, shall not settle badly or 
 cake in the container, shall be readily broken up with a paddle to a 
 smooth uniform paint of good brushing consistency, and shall dry 
 within 18 hours to a full oil gloss, without streaking, running, or 
 sagging. The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller. .The 
 weight per gallon shall be not less than 1534 pounds. The paint 
 shall consist of: | 
 
 Maximum | Minimum 
 
 Per cent Per cent 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 V. METHODS FOR SAMPLING AND TESTING 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available information to ascertain. whether the material meets the 
 specification. 7 cae | , 
 
 1. SAMPLING 
 
 ‘It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible an original unopened 
 container shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine by thorough testing 
 with a paddle or spatula whether the material meets the requirement 
 regarding caking inthe container. He-shall then thoroughly mix the 
 contents of the container and draw a sample of not less than 5 pounds 
 of the thoroughly mixed paint, place it in a clean; dry metal or glass 
 container, which must be filled with the sample, closed with a tight 
 cover, sealed, marked, and sent to the laboratory for test with the 
 inspector’s report on caking in container. 
 
 When requested, a duplicate sample may be taken from the same 
 package and delivered to the seller, and the inspector may take a 
 third sample to hold for test in case of dispute. 
 
 2. LABORATORY EXAMINATION—SEMIPASTE 
 
 (a) CaKING IN ConTAINER.—When an original package is received 
 in the laboratory it shall be weighed, opened, and stirred with a stiff 
 spatula or paddle. The paste must be no more difficult to break up 
 than a normal good grade of semipaste paint. The semipaste shall 
 finally be thoroughly mixed, removed from the container, and the 
 container wiped clean and weighed. This weight subtracted from 
 the weight of the original package gives the net weight of the contents. 
 A portion of thoroughly mixed semipaste shall be placed in a clean 
 container and the portions for the remaining tests promptly weighed 
 out. ; 
 
 (b) Cotor.—Place some of the paint on a clean, clear glass plate. 
 Place some of the standard agreed upon beside the sample on the 
 plate, turn the glass over, and compare the colors. 
 
 (c) Wrrcur PeER GALLON.—From the weight of a known volume 
 of the paste calculate the specific gravity, which multiplied by 8.33 
 gives the weight in pounds per gallon. Any suitable container of 
 known volume may be used for the purpose,. but a short cylinder of 
 heavy glass with rounded bottom about 75 mm high and having a 
 capacity of from 125 to 175 cc (a glass cap to keep dust from reagent 
 bottle stopper) is a convenient apparatus for the purpose. The 
 
SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 5 
 
 capacity of this vessel is determined to within 1 cc. The paste is 
 packed into it until completely full, the top leveled off smooth with 
 a spatula, and weighed to +0.5g. Subtract the weight of the empty 
 container and divide the remainder by the number of cubic centi- 
 meters representing the capacity of the container. The quotient is 
 the specific gravity, which can be thus determined within +2 in the: 
 second decimal place. 
 
 (d) Mrixine wira Linsrrp O1nt.—One hundred grams of ‘the 
 paste shall be placed in a cup, 18 cc linseed oil added slowly with 
 careful stirring and mixing with a spatula or paddle. The resulting 
 mixture must be smooth and of good brushing consistency. 
 
 (e) Moisture anp OTHER Vo.uaTineE Marrer.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish about 
 
 8 cm in diameter, spreading the paste over the bottom. Heat at 
 
 105 to 110° C. for three hours, cool, and weigh. Calculate loss in 
 weight as percentage of moisture and volatile matter. 
 
 (f{) PercentTaGEe or Picment.—Weigh accurately about 15 g of 
 the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
 “extraction mixture” (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add 
 sufficient of the reagent to make a total of 60 cc in the tube. Place 
 the tube in the container of a centrifuge, surround with water, and 
 counterbalance the container of the opposite arm with a similar 
 tube or a tube with water. Whirl at a moderate speed until well 
 settled. Decant the clear supernatant liquid. Repeat the extrac- 
 tion three times with 40 cc of extraction mixture. After drawing off 
 
 - the extraction mixture, set the tube in a beaker of water at about 80° 
 
 C. or on top of a warm oven for 10 minutes, then in an oven at 
 105 to 110° C. for two hours. Cool, weigh, and calculate the per- 
 centage of pigment. Grind the pigment to a fine powder, pass through 
 a No. 80 screen to" remove any skins, and preserve in a . stoppered 
 bottle. - 
 
 (g) PREPARATION oF Farry Acips.—To about 25 g of the paste 
 in’ a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
 (see Reagents) and 75 cc of ethyl alcohol mix and heat uncovered 
 on a steam bath until saponification is complete (about one hour). 
 Add 100 ce of water, boil, add sulphuric acid of specific gravity 1.2 
 (8 to 10 cc in excess), boil, stir, and transfer to a separatory funnel 
 to which some water has been previously added. Draw off as much 
 as possible of the acid aqueous layer and lead sulphate precipitate, 
 wash once with water, then add 50 cc of water and 50 cc of ether. 
 Shake very gently with a whirling motion to dissolve the fatty acids 
 in the ether, but not so violently as to form an emulsion. Draw off 
 the aqueous layer and wash the ether layer with one 15 ce portion of 
 water and then with 5 cc portions of water until free from sulphuric 
 
6 CIRCULAR‘ OF THE BUREAU OF STANDARDS © 
 
 acid. Then draw off the water layer completely. Transfer the ether 
 solution to a dry flask and add 25 to 50 g anhydrous sodium sulphate. 
 Stopper the flask and let stand with occasional shaking at a tem- 
 perature below 25° C. until the water is completely removed from 
 the ether solution, which will be shown by the solution becoming 
 perfectly clear above the solid sodium sulphate. Decant this clear 
 solution, if necessary through a dry filter paper, into a dry 100 ce 
 Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
 CaCl, tower) into the mouth of the Erlenmeyer flask and heat to a 
 temperature below 75° C. on a dry hot plate until the ether is entirely 
 driven off. 
 
 ‘Nots.—It is important to follow all of the details, since ether generally con- 
 tains alcohol and after washing with water always contains water. It is very 
 difficult to remove water and alcohol by evaporation from fatty acids, but the 
 washing of the ether solution and subsequent drying with anhydrous sodium 
 sulphate removes both water and alcohol. Ether, in the absence of water and 
 alcohol, is easily removed from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (hk) Test ror MINERAL OIL AND. OTHER pC ro. ‘pat 
 TER.—Place 10 drops of the fatty acid (g) in a 50 cc test tube, add 
 5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes, 
 add 40 cc of water, and mix; a clear solution indicates that not more 
 than traces of unsaponifiable matter are present. If the solution is 
 not clear, the oil is not pure linseed oil. | 
 
 ({) Iopins Numsper or Farry Actps.—Place a small. quantity of 
 the fatty acids (g) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping from 0.09 g to 0.15 g into a 
 500 cc bottle having a well-ground glass stopper, or an Erlenmeyer 
 flask having a specially flanged neck for the iodine test. Reweigh 
 the burette or beaker and determine amount of sample used. Add 
 10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
 10 cc of chloroform. to each of two empty bottles like that used for 
 the sample. Add to each bottle 25 cc of the Wijs solution (see 
 Reagents) and let stand with occasional shaking for one hour in a 
 dark place at a temperature of from 21 to 23°'C. Add 10 cc of the 
 15 per cent. potassium iodide solution and 100 cc of water, and titrate 
 with standard sodium thiosulphate using starch as indicator. The 
 titrations on the two blank tests should agree within 0.1 cc. From 
 the difference between the average of the blank titrations and the 
 titration on the sample and the iodine value of the thiosulphate 
 solution, calculate the iodine number of the sample tested. (lodine 
 number is centigrams of iodine to 1 g of sample.) If the iodine 
 number is less than 175, the oil does not meet the specification. 
 
 (j) Coarse ParticLes aND Sxins,—-Dry in an oven at 105 to 
 110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
 
SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS ’f 
 
 amount of semipaste containing 10 g of pigment (see 2 (f)), add 100 cc 
 of kerosene, mix thoroughly, and wash with kerosene through the 
 screen, breaking up all lumps, but not grinding. After washing with 
 kerosene until all but the particles too coarse to pass the screen have 
 been washed through, wash all kerosene from the screen with ether 
 or petroleum ether, heat the screen i one hour at 105 to 110° C., 
 cool, and weigh. 
 
 3. ANALYSIS OF PIGMENT 
 
 (2) Quatirative ANaztysis.—A complete qualitative analysis fol- 
 lowing the well-established methods is always advisable, but the work 
 may be usually very much shortened by adding acetic acid slowly to 
 the pigment until all carbonate is decomposed (noting whether any 
 hydrogen sulphide is evolved), then adding a large excess of acid 
 ammonium acetate, boiling, filtering, and testing the filtrate for 
 metals other than lead and zine (especially calcium and barium). 
 The absence of calcium in this filtrate indicates that the extending 
 pigments contain no calcium carbonate or calcium sulphate; the 
 absence of barium indicates that the extending pigments contain no 
 barium carbonate. Test another portion of pigment with hydro- 
 chloric acid (1:1). No odor of hydrogen sulphide should develop. 
 
 (6) Wuitt Leap.—Weigh accurately about 1 g of the pigment, 
 transfer to a 250 ce beaker, moisten with a few drops of alcohol, add 
 slowly dilute (about 20 per cent) acetic acid until all carbonate is 
 decomposed (no further effervescence), then add 50 cc of acid am- 
 monium acetate solution (see Reagents), and boil for two minutes. 
 Decant through a weighed Gooch crucible, leaving any undecom- 
 posed matter in the beaker. Wash the Gooch crucible with a small 
 amount (about 20 cc) of hot water. To the residue in the beaker 
 add 50 cc of the acid ammonium acetate solution and boil two 
 minutes. Filter through the same Gooch crucible, transferring the 
 insoluble matter to the crucible, and wash thoroughly with hot 
 water. Dry the crucible at 105 to 110° C., cool, and weigh. In 
 cases where siliceous material was used as the white extending pig- 
 ments, the material retained on the Gooch crucible will approximate 
 the amount of white extending and tinting pigments. 
 
 Unite the filtrates and pass in a stream of hydrogen sulphide to 
 complete precipitation; let the mixed sulphides of lead and zinc 
 settle, filter on paper, wash with water containing hydrogen sulphide, 
 dissolve the sulphides in hot nitric acid (1:3), and determine lead as 
 sulphate in the usual manner, weighing as PbSO, Multiply lead 
 sulphate weight by the factor 0.883 and report as white lead. 
 
 (c) Zinc Oxtpr.—Weigh accurately about 0.5 g of the pigment, 
 transfer to a 400 cc beaker, add 30 cc of hydrochloric acid (1:2), boil 
 for two or three minutes, add 200 cc of water and a small piece of 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 litmus paper; add strong ammonia until slightly alkaline, render just 
 acid with hydrochloric acid, then add 3 cc of strong hydrochloric acid, 
 heat nearly to boiling, and titrate with standard ferrocyanide as in 
 standardizing that solution (see Reagents). Calculate total zine as 
 zine oxide. 
 
 (d) CaLouLATIONS.—Add the percentage of white lead (see 3(6)), 
 zinc oxide (see 3 (c)), and subtract from 100; the remainder is reported 
 as extending and tinting pigments. 
 
 4. LABORATORY EXAMINATION—MIXED PAINT 
 
 (2) Caxine 1n Container.—Follow the procedure outlined in 2(a), 
 noting that the paint should be no more difficult to break up than a 
 good grade of mixed paint. 
 
 (6) Cotor.—Follow the procedure outlined in 2 (6). 
 
 (c) WricuT per GaLLton.—Weigh a clean, dry, 100 cc graduated 
 flask. Fill to the mark with the thoroughly mixed paint and weigh 
 again. The increase in weight expressed in grams, divided by 100, 
 gives the specific gravity, which multiplied by 8.33 gives the weight 
 in pounds per gallon. 
 
 (d) Brusninc Propertizs AND Time or Dryina.—Brush the 
 well-mixed paint on a suitable panel, which may be ground glass, 
 steel, or well-filled wood. Note whether the paint works satis- 
 factorily under the brush. Place the panel in a vertical position 
 in a well-ventilated room and let stand for 18 hours. The paint 
 should be dry and free from streaks. Flow a portion of the paint on 
 a clean glass plate. Let dry in a nearly vertical position at room 
 temperature (65 to 100° F.). The film shall show no streaking or 
 separation within a distance of 4 inches from the top. 
 
 (e) Warrer.—Mix 100 g of the paint in a 500 cc short-neck glass 
 flask * with 75 cc of toluol (free from water). Connect with the 
 distilling trap and condenser and heat so that the condensed distillate 
 falls from the end of the condenser at the rate of from two to five 
 drops per second. Continue the distillation at the specified rate 
 until no water is visible on any part of the apparatus except at the 
 bottom of the trap. This operation usually requires less than an 
 hour. A persistent ring of condensed water in the condenser tube 
 should be removed by increasing the rate of distillation for a few 
 minutes. The number of cubic centimeters of condensed water 
 
 measured in the trap at room temperature is the percentage of | 
 
 water in the paint. q 
 (f) Votatity THInneR.—Follow the procedure outlined in 2 (e). | 
 
 Correct the result for any water found (see 4 (e)) and report the 
 
 remainder as volatile thinner. 
 
 1 The apparatus for determining water is that described in ‘‘Standard method of test for water in petro- 
 
 leum products and other bituminous materials,’”’ serial designation D-95-24, A. 8. T. M. Standards, 1924, 
 p. 901, and Figure 1 (6) and (c), p. 902. 
 
 i 
 7 
 . 
 
SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 9 
 
 (9) PERCENTAGE oF PIGMENT. Follow the ' aki outlined 
 in 2 (f). 
 
 (h) Tzstina NoNVOLATILE Vienvseil —Follow the procedure out- 
 lined in 2 (g), 2 (h), and 2 (%), except that in the preparation of 
 the fatty acids the mixture of paint and alkali is heated on the 
 steam bath until all volatile thinner is driven off. 
 
 (1) Coarse PARTICLES AND SKINS. —Follow the Peden out- | 
 lined in 2 (J). 
 
 (j) Tzestinc Pigment.—Follow the procedure outlined in 3 (a) 
 to 3 (d), inclusive. 
 
 5. REAGENTS 
 
 (a) Actp Ammonium AcxrtTarn Soxiution.—Mix 150 cc of 80 
 per cent acetic acid, 100 .cc of water, and 95 cc of strong ammonia 
 (specific gravity, 0.90). 
 
 (b) URANYL InpicaTor For Zinc Tirration.—A 5 per cent. 
 solution of uranyl nitrate in water or a 5 per cent solution of uranyl 
 acetate in water made slightly acid with acetic acid. 
 
 (c) STANDARD Porasstum FrrRocyanipe.—Dissolve 22 g of the 
 pure salt’in water and dilute to 1,000 cc. To standardize, transfer 
 about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
 ignited pure zinc oxide to a 400. cc beaker. Dissolve in 10 ec of 
 hydrochloric acid and 20 cc of water. Drop in a small piece of 
 litmus paper, add ammonium hydroxide until slightly alkaline, then 
 add hydrochloric acid until just acid, and then 3 cc of strong hydro- 
 chloric acid. Dilute to about 250 cc with hot water and heat nearly 
 to boiling. Run in the ferrocyanide solution slowly from a burette 
 with constant stirring until a drop tested on a white porcelain plate 
 with a drop of the uranyl indicator shows a brown tinge after stand- 
 ing one minute. A blank should be run with the same amounts of 
 reagents and,water as in the standardization. The amount of 
 ferrocyanide solution required for the blank should be subtracted 
 fromm the amounts used in standardization and in titration of the 
 sample. The standardization must be made under the same con- 
 ditions of temperature, volume, and acidity as obtained when the 
 sample is titrated. 
 
 (d) STANDARD SopiuM Deigdeesiwerd SoLution.—Dissolve pure — 
 sodium thiosulphate in distilled water (that has been well boiled 
 to' free it from carbon dioxide) in the proportion of 24.83 ¢ crystal- 
 lized sodium thiosulphate to 1,000 cc of the solution. It is best to 
 let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Treadwell-Hall, 
 Analytical Chemistry, vol. 2. 6th ed., p. 551.) This solution will 
 be approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust 
 
(10 CIRCULAR OF THE BUREAU OF STANDARDS - 
 
 it to exactly decinormal. Preserve in a stock bottle provider with 
 a guard tube filled with soda lime. 
 
 (e) Srarcu SonvuTion.—Stir up 2 to.3.g of potato starch or 5 g 
 of soluble starch with 100 ce of 1 per cent salicylic acid solution, 
 add 300 to 400 cc boiling water, and boil the mixture until the starch 
 is practically dissolved,,then dilute to 1 liter; 
 
 (f) Extraction Mixturt.— .- 
 
 10 volumes ether (ethyl ether). 
 6. volumes benzol. 
 4 volumes methy] alcohol. 
 
 1 volume acetone: 
 (g) Aqurous Soprum Hyproxipz.—Dissolve 100 g of apres 
 
 hydroxide in distilled water and dilute to 300 ce! 
 
 (h) Potasstum Iopipn Sotutron.—Dissolve 150 g° of polar ten 
 iodide free from iodate in distilled water and dilute to'1j000 éc. 
 
 (1) Wiss Sotution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. ‘There shall be 
 in the solution no sensible excess either of iodine or more particularly 
 of chlorine over that required to form the monochloride. This con- 
 dition is most satisfactorily attained by dissolving in the whole of 
 the acetic acid to be used the requisite quantity of iodine, using 
 gentle heat to assist the solution, if it is found necessary. Dissolve 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
 and is free from reducing impurities in the proportion so that 13 ¢ 
 of iodine will be present in 1,000 ce of solution, Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the 
 remainder until the halogen content of the solution is doubled. 
 Ordinarily it will be found that by passing the chlorine into the main 
 part of the solution until the characteristic color of free iodine has 
 just been discharged, there will be a slight excess of chlorine which 
 is corrected by the addition of the requisite amount of the unchlori- 
 nated portion until all free chlorine has been destroyed. A slight 
 
 excess =i iodine does little or no harm, but excess of" chlorine must be 
 avoide 
 
 (j) Auconotic Soprum Hyproxips Soivitbe paddies pure 
 sodium hydroxide in 95 per cent ethyl alcohol in- the proportion of 
 about 22 g per 1,000 ce. Let stand ina stoppered bottle. Decant 
 the clear liquid into another bottle and keep well stoppered.. This 
 solution should be colorless or only slightly yellow when used, and it 
 will keep colorless longer if the: alcohol is’ previously treated’ with 
 sodium hydroxide (about 80 g to 1,000 cc), oe at about aOR C. 
 for 15 days, and then distilled. ne 
 
 See 
 
SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 11 
 VII. PACKING AND MARKING OF SHIPMENTS 
 
 Shall be in accordance with commercial practice unless otherwise 
 specified. 
 VIII. NOTES 
 
 White paint and tinted paints made on a white base may be ordered _ 
 either in the form of semipaste pigment ground in linseed oil or 
 ready-mixed paint. The semipaste may be purchased by net weight 
 or by volume. The ready-mixed paint should be purchased by 
 volume (231 cubic inches to the gallon). 
 
 For formulas and methods of using this and other materials for 
 similar purposes see Bureau of Standards Technologic Paper No. 274, 
 entitled ‘“‘Use of United States Government Specification Paints and 
 Paint Materials.”’ 
 
 ADDITIONAL COPIES 
 
 O¥ THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
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DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 
 S. W. STRATTON, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 No. 90 
 
 (2d edition. Issued May 23, 1922] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 RED LEAD—DRY AND PASTE 
 
 ee ee! 
 
 FEDERAL SPECIFICATIONS BOARD 
 STANDARD SPECIFICATION NO. 11 
 
 This Specification was officially adopted by the Federal Specifications Board, 
 on February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS 
 
 Page 
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 i. Hin ia da) a ns eso pale eye tik see Ae Aw wea aS ae Coles 3 
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 IAL IOO TAM a a as eal patsaie = our * WARD A ayeclnanana”® 5 
 Ea oe Bla Hs whos eRe cy ce eae ane eases RAL Oso REE es CONS ee ks 7 
 
 1. GENERAL 
 
 Red lead may be ordered in the form of dry pigment or of 
 paste ground in pure raw linseed oil. Two grades of pigment, 
 known as 85 and 95 per cent, may be ordered, and each contract 
 shall state which grade is desired.’ 
 
 Material shall be bought by net weight. 
 
 1 Avoid storing red-lead paste in places of high temperature, as heat accelerates the tendency of this 
 material to cake or harden. Purchasers are cautioned not to buy red lead in paste form unless it is to be 
 used within three months after shipment by the contractor. 
 
 63910°—23 
 
2 Circular of the Bureau of Standards 
 
 (2) Dry Picment.—The pigment shall consist entirely of oxides 
 of lead free from all adulterants and shall meet the following 
 requirements: 
 
 85 sonore: 95 per cent 
 
 grade grade 
 ; Per cent Per cent 
 True red lead (Pb,O,), not less than................--.-.--- 25 95 
 
 Total impurities, including moisture, soluble matter, water— 
 
 and matter insoluble in a mixture of nitric acid and 
 
 hydrogen peroxide, not more than......-...-.-+-----+-++-- 1 1 
 Remainder shall be lead monoxide (PbO). | 
 Coarse particles: Retained on standard: No. 325 screen, not 
 
 more than.........------ heer o-—se8¢ 4p - ete BEE ee 2.0 1.0 
 
 When mixed with raw linseed oil, pss oils and liquid drier 
 in the proportions’ | 
 
 Dry red lead... 00.00 gates eae rains 8) 4s ae pounds.. 30 
 Raw linseed oil: 2. 02... 25 cc hoe on es ce pint..." 3 
 Turpentine WitLA SOL YS Bll dE Ae «Ree lee ae gills.. 2 
 Liquid drier... 5.00.5 .0+ 25s e el ee ese cee) eee ee dos aon 
 
 the resulting paint when brushed on a smooth vertical iron surface 
 shall dry hard and elastic without running, streaking, or sagging. 
 
 (b) PAstE.—The paste shall be made by thoroughly grinding the 
 specified grade of dry pigment with pure raw or refined linseed oil. 
 
 The paste, as shipped by the contractor, and for three months 
 thereafter, shall not be caked in the container and shall readily 
 break up in oil to form a smooth paint of brushing cae 
 The paste shall have the following composition : 
 
 Per cent 
 Pigments. sccn0 vein sdk ev dines eee aco ae C5 oe ee ; 92 
 Linseed olf, 9.30 \h0sssenes cheo tha Beare a! ani ee 6 
 Moisture and other volatile matter. ...... t-s:-.ie70h7. sal venibees bas... 
 Coarse particles and. skins (total residue left on No. 325, + baubre oteaq 
 soreen);- ci o435- Jaspee - faoarpisee> el sp gee = 4 fepem: meny- oa) Fer GS des opercarsk 
 
 When mixed with raw linseed oil, ‘turpentine, and liquid eo 
 in the proportions 
 
 Redilead: paste. wi tuoi hz esis ot dam bemaleaas 9am dtm mh 5 poling ede ee 20 ns sain 
 Raw linseed oil............. 709" te hd Jeerde ivia ediepinesdr aitiaiig bat 
 Turpentine. .... 0.65.2 .te.+ pup = eee ng ee gitis; Stee 
 
Red Lead, Dry and Paste 8 
 
 the resulting paint when brushed on a smooth vertical iron surface 
 shall dry hard and elastic without running, streaking, or sagging. 
 
 2. SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1000 packages be taken as repre-— 
 sentative of the whole. 
 
 With the dry pigment, this package is to be opened by the 
 inspector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. When 
 requested, a duplicate sample may be taken from the same package 
 and delivered to the seller, and the inspector may take a third 
 sample to hold for test in case of dispute. 
 
 With the paste, whenever possible, an original unopened con- 
 tainer shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine by thoroughly 
 testing with a paddle or spatula whether the material meets the 
 requirement regarding not caking in the container (see 4 (a)). 
 After assuring himself that the paste is not caked in the can, the 
 inspector shall draw a sample of not:less than 5 pounds of the 
 thoroughly mixed paste, place it in a clean dry metal or glass 
 container, which must be filled with the sample, closed with a 
 tight cover, sealed, marked, and sent to the laboratory for test 
 with the inspector’s report on caking in container. 
 
 Samples will, in general, be tested by the following methods, 
 but the purchaser reserves the right to apply any additional 
 tests, or use any available information to ascertain whether the 
 material meets the specification. 
 
 3. LABORATORY EXAMINATION, DRY PIGMENT 
 
 (a) QUALITATIVE ANALYSIS.—Follow ordinary methods of 
 qualitative analysis. The material should give a negative test 
 for matter insoluble in a mixture of nitric acid and hydrogen 
 peroxide, atid material other than oxides of lead. (If more than a 
 faint cloud remains after treatment with nitric acid and hydrogen 
 peroxide, it will be necessary to take a weighed sample and deter- 
 mine the percentage of this insoluble matter.) Boil 2 g of the 
 sample with 25 cc of 95 per cent ethyl alcohol, let settle, decant off 
 the supernatant liquid, boil the residue with water, decant as 
 before, and boil the residue with very dilute ammonia. If the 
 
4 Circular of the Bureau of Standards 
 
 alcohol, water, or ammonia are colored, organic coloring matter is 
 indicated, which is cause for rejection. 
 
 (b) True Rep LeEap.—Weigh accurately 1 g of the Pa: into 
 a 200 cc Erlenmeyer flask, add a few drops of distilled water, and 
 rub the mixture to a smooth paste with a glass rod flattened on 
 the end. Mix in a small beaker 30 g of pure crystallized sodium 
 acetate, 2.4 g of pure potassium iodide, 10 cc of water, and 10 ce 
 of 50 per cent acetic acid. Stir until all is liquid, warm gently, 
 and, if necessary, add 2 to 3 cc more water. Cool to room tem- 
 perature and pour into the flask containing the red lead. Rub 
 with the glass rod until nearly all the red lead has been dissolved, 
 add 30 cc of water containing 5 to 6 g of sodium acetate, and 
 titrate at once with standard sodium thiosulphate solution, 
 adding the latter rather slowly and keeping the liquid constantly 
 in motion by whirling the flask. When the solution has become 
 light yellow, rub any undissolved particles up with the rod until 
 free iodine no longer forms, wash off the rod, and add the sodium 
 thiosulphate solution until pale yellow. Add starch solution 
 and titrate until colorless, add standard iodine solution until the 
 blue color is just restored... From the amount of standard iodine 
 solution used, calculate the correction to be applied to the thio- 
 sulphate reading, and calculate true red lead Sindee: value 7 
 thiosulphate X 2.7 = Pb,O, value). 
 
 (c) WATER SOLUBLE MATTER.—Digest 10°g of the acini with 
 200 ce of hot water on a steam bath for r hour; filter and wash 
 with hot water until no residue is left on evaporating a few drops 
 of the washings. Evaporate the filtrate to dryness in a weighed 
 dish on a steam bath, heat for 30 minutes at 105 to 110° C, cool, 
 and weigh. 
 
 (d) Coarse ParticLes.—Dry in an oven at 105 to 110° Ca 
 325 screen, cool, and weigh accurately. Weigh 25 g of the sample, 
 dry at 100° C, transfer to a mortar, add 100 cc kerosene, thor- 
 oughly mix by gentle pressure with a pestle to break up all lumps, 
 wash with kerosene through the screen, breaking up all lumps, but 
 not grinding. After washing with kerosene until all but the parti- 
 cles which are too coarse to pass the screen have been washed 
 through, wash all kerosene from the screen with ether or petro- 
 leum ether, heat the screen for one boee at 105 to 110° hee cool, 
 and weigh.’ oil Paatetredne edt 
 
 2 For a general discussion of screen tests of pigments and data regarding many Slee on the iiatkel, 
 
 see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association onthe 
 United States. 
 
Red Lead, Dry and Paste 5 
 
 (ce) RUNNING, STREAKING, OR SacGcInc.—Mix paint and apply 
 as per specifications. About the smallest amount that can be 
 conveniently made up will be 154 g dry red lead, 40 cc raw lin- 
 seed oil, and 4 cc each of turpentine and liquid drier. 
 
 4. LABORATORY EXAMINATION, PASTE 
 
 (a) CAKING IN CONTAINER.—When an original package is re- 
 ceived in the laboratory, it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paste must be no more diffi- 
 cult to break up and show no more caking than a normal good 
 grade of red-lead paste. The paste shall finally be thoroughly 
 mixed, removed from the container, the container wiped clean, 
 and weighed. This weight subtracted from the weight of the 
 original package gives the net weight of the contents. A portion 
 of the thoroughly mixed paste shall be placed in a clean con- 
 tainer and the portions for the remaining tests promptly weighed 
 out. 
 
 (b) Mrxinc witH LINSEED OIL, RUNNING, STREAKING, AND SAG- 
 GING.—Mix as per specification to a paint, first using only the 
 linseed oil and noting whether the paste breaks up readily and 
 the resulting mixture is smooth. About the smallest amount that 
 can bé conveniently made up will be 154 g red-lead paste, 36 cc 
 raw linseed oil, and 4 cc each of turpentine and liquid drier. 
 
 (c) MoIstURE AND OTHER VOLATILE MATTER.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heatiat 105 to 110° C for three hours, cool, and weigh. Calculate 
 the loss in weight as percentage of moisture and other volatile 
 matter. | 
 
 (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
 of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
 of ‘‘extraction mixture’’ (see reagents), mix thoroughly with a 
 glass rod, wash the rod with more of the extraction mixture, and 
 add sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm with 
 a similar tube or a tube with water. Whirl at a moderate speed 
 untilclear. . Decant the clear supernatant liquid. Repeat the ex- 
 traction twice with 40 cc of extraction mixture, and once with 4o 
 cc of ether. After drawing off the ether, set the tube in a beaker 
 - of water at about 80° C or on top of a warm oven for 10 minutes, 
 
6 Cucular of the Bureau of Standards 
 
 then in an oven at 105 to 110° C for 2 hours. Cool, weigh, and 
 calculate percentage of pigment. 
 
 (¢) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
 to a fine powder, pass through a No. 80 screen to remove any 
 ‘‘skins,’’ preserve in a stoppered tube, and apply tests 3 (a), 
 3 (6), and 3 (c). 
 
 ({) PREPARATION OF Fatrry Acips.—To about 25 g of the paste 
 in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
 (see reagents), and 75 ce of ethyl alcohol, mix and heat uncov- 
 ered on a steam bath until saponification is complete (about one 
 hour). Add 100 cc of water, boil, add sulphuric acid of specific 
 gravity 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a 
 separatory funnel to which some water has been previously 
 added. Draw off as much as possible of the acid aqueous layer 
 and lead sulphate precipitate, wash once with water; then add 
 50 ce water and 50 cc ether. Shake very gently with a whirling 
 motion to dissolve the fatty acids in the ether, but not violently, 
 so as to avoid forming an emulsion. Draw off the aqueous layer 
 and wash the ether layer with one 15 cc portion of water and then 
 with 5 cc portions of water until free from sulphuric acid. Then 
 draw off the water layer completely. ‘Transfer the ether solution 
 to a dry flask, add 25 to 50 g of anhydrous sodium sulphate. 
 Stopper the flask and let stand with occasional shaking atia tem- 
 perature below 25° C until the water is completely removed from 
 the ether solution, which will be shown by the solution becoming 
 perfectly clear above the solid sodium sulphate. Decant this clear 
 solution (if necessary through a dry filter paper) into a dry1o0o cc 
 Erlenmeyer flask. Pass a rapid current of dry air (Pass through 
 CaCl, tower) into the mouth of the Erlenmeyer flask and heat to 
 a temperature below 75° C on a dry hot plate until the ether is 
 entirely driven off. ‘The fatty acids prepared as above wiribnie; be 
 kept in a stoppered flask and examined at once. : 
 
 Notr.—It is important to follow all of the details, since ether generally contains 
 alcohol, and after washing with water always contains water. It is very difficult to 
 remove water and alcohol by evaporation from fatty acids, but the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes 
 both water and alcohol. Ether, in the absence of water and alcohol, is wood removed 
 from fatty acids by gentle heat. 
 
 (g) TEST FOR MINERAL O1L.—Place ro drops of the fait acid Ly) 
 in a 50 cc test tube, add 5 cc of alcoholic soda (see reagents), boil 
 vigorously for five minutes, add 4o ec of water, and mix; a cleat 
 
 solution indicates that not more than traces of ‘unsaponifiable — 
 
ked Lead, Dry and Paste 7 
 
 matter are present. If the solution is not clear, the oil is not pure 
 linseed oil. 
 
 (h) lopInE NuMBER oF Farry Acips.—Place a small quantity 
 of the fatty acids (/) in a small weighing burette or beaker. Weigh 
 accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) to 
 a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
 
 meyer flask having a specially flanged neck for the iodine test. 
 
 Reweigh the burette or beaker and determine the amount of sam- 
 ple used. Add 1tocc of chloroform. Whirl the bottle to dissolve 
 the sample. Add 10 ce of chloroform to two empty bottles like 
 that. used for sample. Add to each bottle 25 ce of the Hanus 
 solution (see reagents) and let stand with occasional shaking for 
 one-half hour. Add 1o,cc of the 15 per cent potassium iodide 
 solution and too ce of water, and titrate with standard sodium 
 
 thiosulphate, using starch as indicator. The titrations on the two 
 
 blank tests should agree within 0.1 cc. From the difference be- 
 tween the average of the biank titrations and the titration on the 
 sample and the iodine value of the thiosulphate solution, calculate 
 the iodine number of the sample tested. (Iodine number is centi- 
 grams of iodine to 1 g of sample.) If the iodine number is less 
 than 170, the oil does not meet the specification. 
 
 (1) Coarse PARTICLES AND SKINS.—Weigh an amount of paste 
 containing 25 g of pigment (see 4 (d)), add 200 cc of kerosene, and 
 wash through a No. 325 screen as in 3 (d). 
 
 5. REAGENTS 
 
 (a) EXTRACTION MIxTURE.— 
 to volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 I volume acetone. 
 (6) AguEous Soprum Hyprox1pE.—Dissolve too g of sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 (c) STANDARD Soprum ‘THIOSULPHATE SOLUTION.—Dissolve 
 
 _ pure sodium thiosulphate in distilled water that has been well 
 
 boiled to free it from carbon dioxide, in the proportion of 24.83 g 
 of crystallized sodium thiosulphate to 1000 cc of the solution. It 
 is best to let this solution stand for about two weeks before 
 standardizing. Standardize with pure resublimed iodine. (See 
 Treadwell-Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) 
 This solution will be approximately decinormal and it is best to 
 
8 Circular of the Bureau of Standards 
 
 leave it as it is after determining its exact iodine value, rathér than 
 to attempt to adjust it to exactly decinormal. Preserve in a stock 
 bottle provided with a guard tube filled with solda lime. 
 
 (d) STARCH SOLUTION.—Stir up 2 to 3 g of potato starch or 5° g 
 of soluble starch with roo cc of 1 per cent salicylic acid solution, 
 add 300 to 400 ce of boiling water, and boil the mixture until vai 
 starch is practically dissolved, then dilute to r liter. 
 
 (¢) STANDARD IODINE SOLUTION.—Dissolve 13 ¢ of veined 
 iodine and 18 g of pure potassium iodide (free from iodates) in 50 
 ce of distilled water, and dilute to tooo ee. Determine its exact 
 value by titrating with the standard sodium thiosulphate solution. 
 
 (7) Porassrum IopIpE SOLUTION.—Dissolve 150 g of potassium 
 iodide, free from iodate, in distilled water and dilute to 1000 cc. 
 
 (9) HANus SoLuTIon.—Dissolve 13.2 g of iodine in 1000 ce of 
 99.5 per cent glacial acetic acid, which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, deter- 
 mined by titration (3 cc of bromine is about the proper amount). 
 The iodine may be dissolved by the aid of heat, but the solution 
 should be cold when the bromine is added. | 
 
 (h) ALCOHOLIC SoprumM HyproxiIpE SoLurIon. anihiedive pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per roooce. Let stand in a stoppered bottle. De- 
 cant the clear liquid into another bottle and keep well stoppered. 
 This solution should be colorless or only slightly yellow when 
 used, and it will keep colorless longer if the alcohol is previously 
 treated with sodium hydroxide (about 80 g to 1000 aes kept at 
 about 50° C for 15 days, and then distilled. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 5CENTS PER COPY 
 V 
 
DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 S. W. STRATTON, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS 
 No. 91 
 
 [2d edition, issued June 21, 1922] . et 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 3 OCHER, DRY AND PASTE 
 
 FEDERAL SPECIFICATIONS BOARD 
 STANDARD SPECIFICATION NO. 12 
 
 This Specification was officially adopted by the Federal Specifications Board 
 on February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS 
 : . Page 
 Ea ils oh erie ard ab tunchams I 
 ee re dass pu nne ccd nswk vplav ages {ERE 2 
 3 Laboratory @xamination of dry pigment. 2. 2 A et 2 
 4a;leaboratory examination of: paste, :ac)ay: .celad.ace. 1. al Olinet.&. be 4 
 a oh FE 6 a fit it Rik i es 7 
 1. GENERAL 
 
 Ocher may be required in the form of dry pigment or paste 
 ground in linseed oil; it shall be prepared in accordance with the 
 most improved methods. Grinding in oil shall be thorough and 
 the vehicle shail be pure raw linseed oil. 
 
 The material shall be bought by net weight. 
 
 “ (a) Dry PicmentT.—The pigment shall be a hydrated oxide of 
 iron permeating a siliceous base, and shall be free from added 
 impurities. It shall conform to the following requirements: 
 
 Color—Color Strength—T one.—Equal to sample mutually agreed 
 on by buyer and seller. 
 
 Maximum |} Minimum 
 
 . Percent | Percent 
 Coarse particles: Retained on standard No, 325 screen... --...-..----------+-+++- 130 
 
 UN rok ay. snip in AM wh xn do yb os oink ice eh singe ake <he cag aaes AeA pie ce etna aan 17 
 OE a SR Oh LL BB LR ah alin a es fae rete Pickin eis o lanawstaenwa 4 
 Ua ehromarern (cei) b opoe ba 4 5- <p tace Chl.) «SEP eee SSID... SAIS SP TT. None) {ii52). Jc ok 
 a a io nce ni i i ce hae a Se eh ne i i eed None, |..5.\-.-t.e0s 
 
 109839°-—22 
 
2 Circular of the Bureau of Standards 
 
 (6) PasteE.—Ocher in paste form shall consist of: 
 
 Maximum | Minimum 
 
 Per cent Per cent 
 
 Pigment.........--.. Bee er ita tres. ar ey OE ASE REST <3. oT -eey. eek Wire 71 69 
 Binseed. Off. oo. cee ecb n cua lak ceewe oabeeb oe euwalnce chats Pd eEe cee 31 29 
 Molsture and volatile matter... 1. ..eul deus ss op dus gl abn cuake~ bat eee O.8 jose. ue eee 
 Coarse particles and “‘skins’’ (total residue left on No. 325 screen) based on pig- 
 
 111, | See RGR CAMs we rts gh a beh liners, created apne acpntnne. he a SiS iogeeeeearerk 
 
 NotE.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
 reserves the right to use any additional available information to ascertain whether the material meets the 
 specification. 
 
 2. SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1000 pag age* shall be taken 
 as representative of the whole. 
 
 With the dry pigment, this package. shall os opened by the 
 inspector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. 
 
 With the paste, whenever possible, an original unopened con- 
 tainer shall be sent to the laboratory; and when this is for any 
 reason not done, the inspector shall determine, by thorough test- 
 ing with a paddle or spatula, whether the material meets the 
 requirement regarding not caking in the container. (See 4 (a).) 
 He shall then thoroughly mix the contents of the container and 
 draw a sample of not less than 5 pounds. This sample shall be 
 placed in a clean, dry, metal or glass container which it must 
 nearly fill. The container shall be closed with a tight cover, sealed, 
 marked, and sent to the laboratory for test with the inspector: s 
 report on caking. 
 
 When requested, a duplicate sample may be aii from the 
 same package and delivered to the seller, and the inspector. may 
 take a third sample to hold for test in case of Hispute. 
 
 3. LABORATORY EXAMINATION OF DRY PIGMENT 
 
 (a) CoLOR AND TONE.—Weigh 1 g each of the color and esta: 
 ard and rub up separately on a glass plate or stone slab, using 
 the same amount of bleached linseed oil in each case. Place por- 
 tions of each side by side on a clean strip of*glass, turn the glass 
 over and compare the colors. Rubbing up (mixing with oil) is 
 best done with a muller, and should be such that no lumps remain’ 
 and that the consistency of both paste portions is ey same. 
 
Specification for Ocher, Dry and Paste 3 
 
 Smear (with the finger) portions of the pastes on a clear glass 
 strip and compare the tone by transmitted light. 
 
 (6) CoLoR STRENGTH.—Weigh accurately 0.05 g each of the 
 color and standard and two portions of 1 g each of the zinc oxide. 
 Add the color to one of the portions of zinc oxide and the standard 
 to the other and rub up separately in linseed oil until on spreading - 
 out no dark streaks are visible. Place the color and standard tints 
 side by side on a clean glass strip, turn the strip over and compare. 
 
 (c) CoARSE. PARTICLES."—Dry in an oven at 105 to 110° C a 
 325 screen, cool and weigh accurately. Weigh ro g of the sample; 
 dry at 100° C, transfer to a mortar, add'100 cc kerosene, thoroughly 
 mix by gentle pressure with a pestle to break up all lumps; wash 
 with kerosene through the screen, breaking up all lumps but not 
 grinding. After washing with kerosene until all but the particles 
 which are too coarse to pass the screen have been washed through, 
 wash all kerosene from the screen with ether or petroleum ether, 
 heat the screen for one hour at 105 to 110° C, cool and weigh. 
 
 (d) Morsture.—Place 1 g of the sample in a wide-mouth, short 
 weighing tube provided with a glass stopper, and weigh accu- 
 rately. Heat with stopper removed for two hours at a tempera- 
 ture between 100 and 105° C. Insert stopper, cool and weigh. 
 Calculate loss in weight as moisture. 
 
 (e) ORGANIC COLORING MATTER (A. S. T. M. “Standards,” 1918, 
 _ p. 656).—Test the pigment successively with hot water, 95 per 
 cent alcohol, alcoholic sodium hydroxide and acetic acid. Chloro- 
 form, sodium hydroxide, sulphuric acid, hydrochloric acid-stan- 
 nous chloride solution, and other reagents may be tried. The 
 solutions should remain colorless: The presence of an organic 
 color may often be detected by the characteristic odor given off 
 on ignition. | 
 
 ({) Toray IRon Ox1pDE.—Ignite 1 g of the sample in a porcelain 
 crucible at a dull red heat to destroy organic matter. Transfer to 
 a 500 cc Erlenmeyer flask and add 20 cc of 1 : 1 hydrochloric acid. 
 Digest just short of boiling until no dark specks can be seen in the 
 insoluble residue. When the residue is light in color, the solution 
 of iron may be considered complete. Dilute to 100 cc and without 
 filtering, add 3 g of granulated zinc; put a funnel in the neck of 
 the flask and heat when the action slackens; if basic iron salts 
 separate out, add a few drops of hydrochloric acid. When the 
 
 1 For a general discussion of screen tests of pigments and data regarding many pigments on the 
 
 market, see Circular No, 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Associa- 
 tion of the U. S. . 
 
4 Circular of the Bureau of Standards 
 
 reduction is complete, add 30 ce of sulphuric acid (1:2) and as» 
 soon as the residual zinc is dissolved, wash down the funnel and 
 neck of the flask with a fine jet of water. Now add 200 cc of cool 
 water and 30 ce of titrating solution (see reagents) and titrate 
 with standard potassium permanganate. Rum a blank.on the 
 zinc and calculate ferric oxide (Fe,O,).. Any other aceurate 
 method for determining iron may be used at the option of the 
 analyst. | 
 
 (g) Test For LEAD AND CALCIUM BY THE wast Quake 
 Metuops.—If calcium is present in appreciable amount, determine 
 it as follows: Ignite 2.5 gin a porcelain crucible at'a dull red heat 
 to destroy organic matter. ‘Transfer to a 500 cc graduated flask; 
 add 100 cc of 1 : 1 hydrochloric acid. Digest just short of boiling 
 until no dark specks:'can be seen in the insoluble residue; add 
 ammonia in slight excess and about 2 cc of hydrogen peroxide 
 solution; cool, dilute to 500 cc; mix thoroughly, filter through a 
 dry paper. Take roo cc of the filtrate (corresponding to 0.5 g 
 of sample), heat to boiling, add a few drops of ammonia and an 
 excess of a hot saturated ammonium oxalate solution. Continue 
 boiling until the precipitate becomes granular; let stand about 
 30 minutes, filter, wash with hot water until free from ammonium 
 oxalate. Pierce the apex of the filter with a stirring rod and 
 wash the precipitate into the beaker with hot water; pour warm 
 dilute sulphuric acid (1 : 4) through the paper and wash a few 
 times. Add about 30 cc of sulphuric acid (1 : 4), dilute to about 
 250 cc with hot water and titrate at once with standard potas- 
 sium permanganate solution (the solution should not be below 
 60° C when the end point is reached). Calculate to CaO. (The 
 Fe value of KMnO,x0.502=CaO value.) 
 
 4, LABORATORY EXAMINATION OF PASTE 
 
 (a) CAKING IN CONTAINER.—When an original package is 
 received in the laboratory it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paste must be no more diffi- 
 cult to break up and show no more caking than a normal good 
 grade of ocher paste. The paste shall be finally thoroughly mixed, 
 removed. from the container, and the container wiped clean’ and 
 weighed. ‘This weight subtracted from the weight of the original 
 package gives the net weight of the contents. A portion of the 
 thoroughly mixed paste shall be placed in a clean container and 
 portions for the remaining tests promptly weighed out from it. _ 
 
Specificaiion for Ocher, Dry aud Paste 5 
 
 (6) MrxiInc with O11, or THINNING.—Add sufficient linseed 
 oil to 100 g of the sample to make a liquid paint of proper con- 
 sistency for application with a brush, noting the amount of oil 
 necessary. Note the smoothness with which the paint works 
 under the brush. 
 
 (c) MoistuRE AND OTHER VOLATILE Matrer.—Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heat at 105 to 110° C for three hours, cool, and weigh. Calculate 
 loss in weight as percentage of moisture and volatile matter. 
 
 (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
 of the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
 “extraction mixture’’ (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add 
 sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm 
 with a similar tube or a tube with water. Whirl at a moderate 
 speed until well settled. Decant ‘the clear supernatant liquid. 
 Repeat the extraction twice with 40 cc of extraction mixture and 
 once with 40 cc of ether. After drawing off the ether, set the 
 tube in a beaker of water at about 80° C or on top of a warm 
 oven for 10 minutes, then in an oven at 105 to 110° € for two 
 hours. Cool, weigh, and calculate the percentage of pigment. 
 
 (e) EXAMINATION OF THE PIGMENT.—Grind the pigment from 
 (d) to a fine powder, pass through an 80-mesh screen to remove 
 any skins, preserve in a stoppered bottle, and examine as under 
 3(e), 3(/), and 3(9). 
 
 (f) Coton, ToNE, AND COLOR STRENGTH.—Extract the pig- 
 ment from the vehicle with extraction mixture as in 4(d), except 
 that it is not necessary to accurately. weigh the amount taken, 
 and after washing with ether, dry in a vacuum at a temperaturé 
 not above 70° C. Grind this extracted pigment fine enough to 
 pass a No. 80 screen to remove skins, and test as under 3(a) 
 and 3(b). 
 
 _(g) COARSE PARTICLES AND, SKINS.—Weigh an amount of paste 
 containing 10 g of pigment (see 4(d)), add 200 cc of kerosene, 
 and wash through a No. 325 screen as in 3(c). 
 
 (h) PREPARATION OF Farry Acips.—To about 25 g of the paste 
 in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
 (see reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 
 
6 Circular: of the Bureau of Standards 
 
 on a steam bath until saponification is complete (about one 
 hour). Add 100 ce of water, boil, add sulphuric acid of specific 
 gravity 1.2 (8 to ro ce in excess), boil, stir, and transfer to a 
 separatory funnel to which some water has been previously 
 added. Draw off as much as possible of the acid aqueous layer 
 and insoluble mineral matter, wash once with water, then add 
 50 cc of water and 50 cc of ether. Shake very gently with a 
 whirling motion to dissolve the fatty acids in the ether, but 
 not so violently as to form an emulsion: Draw off the aqueous 
 layer and wash the ether layer with one 15 ce portion of water . 
 and then with 5 cc portions of water until free from sulphuric 
 acid. Then draw off the water layer completely. Transfer the 
 ether solution to a dry flask and add 25 to 50 g anhydrous 
 sodium sulphate. Stopper the flask and let stand with occasional 
 shaking at a temperature below 25° C until the water is com- 
 pletely removed from the ether solution, which will be shown by 
 the solution becoming perfectly clear above the solid sodium 
 sulphate. Decant this clear solution, if necessary, through a dry 
 filter paper, into a dry 100 cc Erlenmeyer flask. Pass a rapid 
 current of dry air (pass through a CaCl, tower) into the mouth of 
 the Erlenmeyer flask and heat to a temperature below 75° C on 
 a dry hot plate until the ether is entirely driven off: The fatty 
 acids prepared as above should be kept in a stoppered flask ue 
 examined at once. 
 
 Note. It is important to follow all of the details, since ether generally contains 
 alcohol and, after washing with water, always contains water. It is very difficult to 
 remove water and alcohol by evaporation from fatty acids, but the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes both 
 water and alcohol. Ether, ia the absence of water and alcohol, is easily’ removed 
 from fatty acids by gentle heat. 
 
 (i) THST FoR MINERAL OIL AND OTHER UNSAPONIFIABLE MAT- 
 TER.—Place to drops of the fatty acids (h) in a 50 cc test tube, 
 add 5 cc of alcoholic soda (see Reagents), boil vigorously for 5 
 minutes, add 40 cc of water and mix; a clear solution indicates 
 than not more than traces of unsaponifiable matter are present. 
 If the solution is not clear, the oil is not pure linseed oil. 
 
 (7) loprine NuMBER OF Farry Actps.—Place a small quantity 
 of fatty acids (k) in a small weighing burette or beaker. Weigh 
 accurately. ‘Transfer, by dropping, about 0.15 g (0.10 to 0.20 g) 
 to a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
 meyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine amount of sample 
 
Specification for Ocher, Dry and Paste ‘| 
 
 used.. Add 10 cc of chloroform. Whirl the bottle to dissolve 
 the sample. Add 10 ce of chloroform to each of two empty 
 bottles like that used for the sample. Add to each bottle 25 cc 
 of the Hanus solution (see Reagents) and let stand, with occa- 
 sional shaking, for one-half hour. Add 10 ce of the 15 per cent 
 potassium iodide solution and 100 ce of water, and titrate with | 
 standard sodium thiosulphate using starch as indicator. The 
 titrations on the two blank tests should agree within o.1 cc. 
 From the difference between the average of the blank titrations 
 and the titration on the sample, and the iodine value of the thio- 
 sulphate solution calculate the iodine number of the sample tested. 
 (Jodine number is centigrams of iodine to 1. g of sample.) If the 
 iodine number is less than 170, the oil does not meet the 
 specification. 
 5. REAGENTS 
 
 (a) EXTRACTION MrxTuRE.— 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 1 volume acetone. 
 (6) AguEOous Soprum HyproxipE.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 (c) SYANDARD Soprum ‘THIOSULPATE SoLUTION. — Dissolve 
 . pure sodium thiosulphate in distilled water (that has been well 
 boiled to free it from carbon dioxide) in the proportion of 24.83 g 
 crystallized sodium thiosulphate to 1000 cc of the solution. It is 
 best to let this solution stand for about two weeks before standard- 
 izing. Standardize with pure resublimed iodine. (See Treadwell- 
 Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This solution 
 will be approximately decinormal, and it is best to leave it as it is 
 after determining its exact iodine value, rather than to attempt 
 to adjust it to exactly decinormal. Preserve in a stock bottle 
 provided with a guard tube filled with soda lime. | 
 ~(d) SrarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 
 5 g of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
 add 300 to 400 cc boiling water, and boil the mixture until the 
 starch is practically dissolved, then dilute to 1 liter. 
 (ec) Potassium IoprpE SoLwutTron.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1000 cc. 
 (f) Hanus SoLutTion.—Dissolve 13.2 g of iodine in 1000 cc of 
 99.5 per cent glacial acetic acid, which will not reduce chromic 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (b) Cotor.—Follow the procedure outlined in 3 (0). 
 
 (c) Wricut pER GaLton.—Weigh a clean, dry, 100 cc graduated 
 flask. Fill to the mark with the thoroughly mixed paint and weigh 
 again. The increase in weight expressed in grams, divided by 100, 
 gives the specific gravity, which multiplied by 8.33 gives the weight 
 in pounds per gallon. 
 
 (2) BrusHinc PROPERTIES AND Time oF Dryine.—Brush the 
 well-mixed paint on a suitable panel, which may be ground glass, 
 steel, or well-filled wood. Note whether the paint works satis- 
 factorily under the brush. Place the panel in a vertical position 
 in a well-ventilated room and let stand for 18 hours. The paint 
 shall be dry, smooth, and free from streaks. Flow a portion of the 
 paint on a clean glass plate. Let dry in a’nearly vertical position 
 at room temperature (65 to 100° F.). The film shall show no streak- 
 ing or separation within a distance of 4 inches from the top. 
 
 (e) Watrer.—Mix 100 g of the paint in a 500 cc short-neck glass 
 flask } with 75 ec of toluol (free from water). Connect with the 
 distilling trap and condenser, and heat so that the condensed dis- 
 tillate falls from the end of the condenser at the rate of from two to 
 five drops per second. Continue the distillation at the specified 
 rate until no water is visible on any part of the apparatus except at 
 the bottom of the trap. This operation usually requires less than 
 an hour. A persistent ring of condensed water in the condenser 
 tube should be removed by increasing the rate of distillation for a 
 few minutes. The number of cubic centimeters of condensed water 
 measured in the trap at room temperature is the percentage of 
 water in the paint. 
 
 (f) Vouatite TxHiInner.—Follow the procedure outlined in 2 (e). 
 Correct the result for any water found (see 4 (e)) and ener the 
 remainder as volatile thinner. 
 
 (9) PerceNTAGE oF PiamMEeNT.—Follow the procedure outlined 
 in 2 (f). 
 
 (h) Testinc NonvoLaTILE VeutcLte.—Follow the preted site out- 
 lined in 2 (g), 2 (A), and 2 (i), except that in the preparation of the 
 fatty acids the mixture of paint and alkali is heated on the steam 
 bath until all volatile thinner is driven off. | 
 
 (1) CoaRsE PARTICLES AND SKINS. oa the prokeuint out- 
 lined in 2 (7). 
 
 (j) Testing Picment.—Follow the ihn dutlfineed in 3 (a) to 
 4 (d), inclusive. 
 
 1 The apparatus for determining water is that described in ‘‘Standard method of test for water in petro- 
 
 leum products and other bituminous materials,” Serial Designation D-95-24, A. 8S. T. M. Standards, 
 1924, p. 901, and Figure 1 (6) and (c), p. 902. 
 
Se 
 
 SPECIFICATION FOR IRON OXIDE AND IRON HYDROXIDE 9 
 
 5. REAGENTS 
 
 (a) Extraction MixtTurE.— 
 10 volumes ether (ethyl ether). 
 ‘6 volumes benzol. 
 4 volumes methyl! alcohol. 
 1 volume acetone. 
 
 (6) Aqurous Sopium Hyproxipe.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 
 (c) Sranparp Sopium THIosuLPHATE SoLuTION.—Dissolve pure 
 sodium thiosulphate in distilled water (that has been well boiled 
 to free it from carbon dioxide) in the proportion of 24.83 ¢ of crys- 
 tallized sodium thiosulphate to 1,000 cc of the solution. It is best 
 to let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Treadwell-Hall, 
 Analytical Chemistry, vol. 2, 6th ed., p. 551.) This solution will be 
 approximately decinormal, and it is best to leave it as it is aiter 
 determining its exact iodine value, rather than to attempt to adjust 
 it to exactly decinormal. Preserve in a stock bottle provided with a, | 
 guard tube filled with soda lime. 
 
 (d) Starcn SoLvutTion.—Stir up 2 to 3 g of potato starch or 5 g 
 of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
 add 300 to 400 cc boiling water, and boil the mixture until the starch | 
 is practically dissolved, then dilute to 1 liter. 
 
 (ec) Porasstum lopipr Sotution.—Dissolve 150 g of idfasslum 
 iodide free from iodate in distilled water and dilute to 1,000 ce. 
 
 (f) Wiss Sotution.—The preparation of the iodine tidhobHiWvide 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine or more particularly 
 of chlorine.over that required to form the monochloride. This con- 
 dition is most satisfactorily attained by dissolving in the whole of 
 the acetic acid to be used the requisite quantity of iodine, using 
 gentle heat to assist the solution, if it is found necessary. Dissolve 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
 and is free from reducing impurities in the proportion so that 13 ¢ 
 of iodine will be present in 1,000 cc of solution. Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the 
 remainder until the halogen content of the solution is doubled. 
 Ordinarily it will be found that by passing the chlorine into the 
 main part of the solution until the characteristic color of free iodine 
 has just been discharged, there will be a slight excess of chlorine 
 which is corrected by the addition of the requisite amount of the 
 unchlorinated portion until all free chlorine has been destroyed. A 
 slight excess of iodine does little or no harm, but excess of chlorine 
 must be avoided. 
 
10 CIRCULAR OF THE BUREAU OF STANDARDS | 
 
 (g) Auconotic Soprum Hyproxipr Soxution.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per 1,000 cc, Let stand in a stoppered bottle. Decant 
 the clear liquid into another bottle and keep well stoppered. This 
 solution should be colorless or only slightly yellow when used, and 
 it will keep colorless longer if the alcohol is previously treated with 
 sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
 15 days, and then distilled. : 
 
 (h) Stanparp Potassium DicHromaTE SoLution.—Dissolve 4.903 
 g of pure, dry, crystallized potassium dichromate in water and 
 dilute to 1,000 ce (1 cc=0.008 g Fe,0;). Determine its exact iron 
 value with Bureau of Standards Standard Sample No. 27a, Sibley 
 Iron Ore. 
 
 (1) PHospHoric Actp Mrixture.—Mix 150 cc of sulphuric acid 
 (specific gravity 1.84) with 150 ce of phosphoric acid (specific gravity 
 1.7), and dilute the mixture with water to 1,000 ce. ; 
 
 (7) DipHenyLaminE INpIcator.—Dissolve 1 g of diphenylamine 
 in 100 cc of concentrated sulphuric acid. Use three drops of the 
 
 * solution as indicator. 
 
 (k) Stannous CuLoripE So.ution.—Dissolve 50 g of the crystal- 
 lized salt (SnCl,.2H,O) in 300 ce of concentrated hydrochloric acid 
 and dilute with water to 500 cc. Keep the clear solution in a 
 tightly stoppered bottle containing some metallic tin. 
 
 (1) Mercuric Cuioripe Souution.—A saturated solution of 
 HgCl, (60 to 100 g per liter). 
 
 (m) Potassium FErricyanipe SoLution.—A 1 per cent solution 
 is satisfactory. Dissolve a piece half as big as a small pea in 50 cc 
 of water. This solution must be made fresh when wanted, because 
 it does not keep. 
 
 VII. PACKING AND MARKING OF SHIPMENTS 
 
 Shall be in accordance with commercial practice unless ee 
 specified. 
 VIII. NOTES 
 
 This specification applies to iron-oxide and iron-hydroxide paints 
 of red and brown colors. The paint may be ordered in the form of 
 either semipaste paint or ready-mixed paint. The semipaste may 
 be purchased by net weight or by volume. The ready-mixed paint 
 should be purchased by volume (231 cubic inches to the gallon). 
 
 For formulas and methods of using this material and information 
 regarding the use of other specification paint materials see Bureau 
 of Standards Technologic Paper No. 274, entitled “Use of United 
 States Government Specification Paints and Paint Materials.” 
 
ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
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 WASHINGTON, D. C. 
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U. S. Gov't 
 Master 
 Specification 
 
 No. 14b 
 
 DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 GEORGE K. BURGESS, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 94 
 
 [3d-edition, issued April 29, 1927] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATIONS 
 FOR PAINT, BLACK, SEMIPASTE AND READY MIXED 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION NO. 14b 
 [Revised September 2, 1925] 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on February 3, 1922, for the use of the departments and independent 
 establishments of the Government in the purchase of black paint, semipaste 
 and ready mixed. 
 
 [The date on which the technical requirements of this revision of this specification became mandatory 
 for all departments and independent establishments of the Government was September 2, 1925. The 
 changes included in this revision were authorized by the Federal Specifications Board and promulgated ina 
 circular letter on above revision date. 
 
 CONTENTS 
 
 VI. Methods for sampling and testing. ______2 
 
 VU. Packing and marking of shipments_.-__.____2__. CLUES SMT pi 
 BNO on cr egah et eee ee ee ee 
 43230°—27 
 
 BOON SOPWWwWHDY DYDD wd 
 
bo 
 
 CIRCULAR OF THE BUREAU OF STANDARDS 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification. 
 Il. TYPES 
 
 Black paint shall be of the following types: Semipaste in linseed 
 oil and ready-mixed. 
 
 Ill. MATERIAL AND WORKMANSHIP 
 See detail requirements. 
 IV. GENERAL REQUIREMENTS 
 See detail requirements. 
 V. DETAIL REQUIREMENTS 
 
 1. PIGMENT 
 
 The pigment in both semipaste and ready-mixed paints shall 
 consist of carbon, lead oxide, insoluble mineral material, and, at the 
 option of the manufacturer, oxide of iron. The pigment shall show 
 on analysis not less than 20 per cent of carbon and not less than 5 
 per cent of lead oxide calculated as Pb;0,. The total of the lead oxide, 
 
 iron oxide, insoluble mineral material, and loss on ignition shall be not 
 
 less than 90 per cent. 
 2. LIQUID 
 
 The liquid in semipaste paint shall be entirely linseed oil; in ready- 
 mixed paint it shall contain not less than 80 per cent linseed oil, the 
 balance to be combined drier and thinner. The thinner shall. Ds 
 
 turpentine, volatile mineral spirits, or a mixture thereof. 
 3. SEMIPASTE 
 
 Semipaste shall be made by thoroughly grinding the pigment with 
 linseed oil. 
 
 The semipaste as received and three months thereafter shall be 
 not caked in the container and shall break up readily in linseed 
 oil to form a smooth paint of brushing consistency. It shall mix 
 readily with linseed oil, turpentine, or volatile mineral spirits, or 
 any combination of these substances, in all proportions. without 
 curdling. The color and hiding power when specified shall be equal 
 to that of a sample mutually agreed upon by buyer and seller. 
 The weight per gallon shall be not less than 10 pounds. ‘The paste 
 shall consist of: sist 
 
 ) 
 | 
 i 
 : 
 | 
 q 
 
 es ee 
 
 ee ee ee ee ee ee atl 
 
 i ee a ee 
 
_ SPECIFICATION FOR BLACK PAINT... . 3 
 
 Maximum } Minimum 
 —_— 
 Per cent °| Per cent 
 ee eo BES SS ae Se ae i Se a, 52 48 
 Linseed oil__.2__- oh Sar ee ee SCS AR CR i Me Re Lae 52 . 48 
 
 4. READY-MIXED PAINT 
 
 Ready-mixed paint shall be well ground, shall not settle badly or 
 cake in the container, shall be readily broken up with a paddle to a 
 smooth uniform paint of good brushing consistency, and shall dry 
 within 18 hours to a full oil gloss, without streaking, running, or 
 sagging. The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller. 
 The weight per gallon shall be not less than 9 pounds. The paint 
 shall consist of: 
 
 | Maximum |} Minimum 
 <==>"Senee ge tesenemanmne emer ape ee cn Ee ae hee es 
 
 Per cent Per cent 
 
 ee ee ee 32 28 
 aig (containing at least 80 per cent linseed LN ae Se SE ES BMY 8 2 72 : 68 
 ee eR et a Re abana one gee mma cdennse waraint hs. Rs Be nahn ee 
 Coarse particles and ‘“‘skins” (total residue retained on No. 325 screen based on 
 pigment) csn.3 25... LO eR ESSE EAS Se a Ss ee ERTS Tag 4 ed Al hI ere Soe 
 er Feit eg 
 
 VI. METHODS FOR SAMPLING AND TESTING 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available information to ascertain whether the material meets the specifi- 
 cation. 
 
 1. SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible an original unopened 
 container shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine by thorough testing 
 with a paddle or spatula whether the material meets the require- 
 ments regarding caking in the container. He shall then thoroughly 
 mix the contents of the container and draw a sample of not less than 
 5 pounds of the thoroughly mixed paint, place it in a clean, dry metal 
 or glass container, which it shall nearly fill. The container shall be 
 closed with a tight cover, sealed, marked, and sent to the laboratory 
 for test with the inspector’s report on caking. 
 
 When requested, a duplicate sample may be taken from the same 
 package and delivered to the seller, and the Inspector may take a 
 third sample to hold for test in case of dispute. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 2. LABORATORY EXAMINATION—SEMIPASTE 
 
 (a) Caxine 1n ConTatner.—When an original package is received 
 in the laboratory, it shall be weighed, opened, and stirred with a stiff 
 spatula or paddle. The paste must be no more difficult to break up 
 than a normal good grade of semipaste paint. The semipaste shall 
 finally be thoroughly mixed, removed from the contaimer, and the 
 container wiped clean and weighed. This weight subtracted from 
 the weight of the original package gives the net weight o the con- 
 tents. A portion of thoroughly mixed semipaste shall be placed in a 
 clean container and the portions for the remaining tests promptly 
 weighed out. cod Ri eteaes 
 
 (b) Cotor.—Place some of the paint on a clean clear glass plate. 
 Place some of the standard agreed upon beside the sample on the 
 plate, turn the glass over, and compare the colors. . | 
 
 (c) We1cut per GaLton.—From the weight of a known volume 
 of the paste calculate the specific gravity, which multiplied by 8.33 
 vives the weight in pounds per gallon. Any suitable contaimer of 
 known volume may be used for the purpose, but a short cylinder 
 of heavy glass with rounded bottom about 75 mm high and having 
 a capacity of from 125 to 175 ce (a glass cap to keep dust from 
 reagent bottle stopper) is a convenient apparatus for the purpose. 
 The capacity of this vessel is determined to within 1 cc. The paste 
 is packed into it until completely full, the top leveled off smooth 
 with a spatula, and weighed to 40:5 g. Subtract the weight of the 
 empty container and divide the remainder by the number of cubic 
 centimeters representing the capacity of the container. The quotient 
 is the specific gravity, which can be thus determined within +2 in 
 the second decimal place. __ : 
 
 (d@) Mrxine witn Linsnep Orn.—One hundred grams of the paste 
 shall be placed in a cup, 70 cc linseed oil added slowly with careful 
 stirring and mixing with a spatula or paddle. The resulting mixture. 
 must be smooth and of good brushing consistency. 
 
 (ec) Moisture aNp Oruer VouaTite Marrer.—Weigh accurately 
 from 3 to 5 g of the paste into a tared flat-bottomed dish about 8 
 cm in diameter, spreading the paste over the bottom. Heat at 105 
 to 110° O. for three hours, cool, and weigh. Calculate loss in weight 
 as percentage of moisture and volatile matter. Hes 
 
 (f) Percentage or Prament.—Weigh accurately about 15 ¢g of 
 the paste into a weighed centrifuge tube. Add 20 to 30 cc of “extrac- 
 tion mixture” (see reagents), mix thoroughly with a glass rod, wash 
 the rod with more of the extraction mixture, and add sufficient of 
 
 the reagent to make a total of 60 ce in the tube. Place the tube in 4 
 
 the container of a centrifuge, surround with water, and counter- 
 balance the container of the opposite arm with a similar tube or a 
 tube with water. Whirl at a moderate speed until well settled. 
 
SPECIFICATION FOR BLACK PAINT D 
 
 Decant the clear supernatant liquid. Repeat the extraction three 
 times with 40 cc of extraction mixture. After drawing off the ex- 
 traction mixture, set the tube in a beaker of water at about 80° C. 
 or on top of a warm oven for 10 minutes, then in an oven at 105 to 
 110° C. for two hours. Cool, weigh, and calculate the percentage 
 of pigment. Grind the pigment to a fine powder, pass through a 
 No. 80 screen to remove any skins, and preserve in a stoppered 
 bottle. 
 
 Notr.—If the pigment fails to settle with the “extraction mixture,’’ use 
 petroleum ether, 100 per cent of which distils below 70° C., 75 per cent below 
 50° C., with an initial boiling point of 28° C. 
 
 (g) PREPARATION oF Farry Acips.—To about 25 g of the paste 
 in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
 (see Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 
 on a steam bath until saponification is complete (about one hour). 
 Add 100 cc of water, boil, add sulphuric acid of specific gravity 1.2 
 (8 to 10 cc in excess), boil, stir, and transfer to.a separatory funnel to 
 which some water has been previously added. Draw off as much as 
 possible of the acid aqueous layer, wash once with water, then add 
 50 cc of water and 50 ccof ether. Shake very gently with a whirling 
 motion to dissolve the fatty acids in the ether, but not so violently 
 as to form an emulsion. Draw off the aqueous layer and wash the 
 ether layer with one 15 cc portion of water and then with 5 cc por- 
 tions of water until free from sulphuric acid. Then draw off the 
 water layer completely. Transfer the ether solution to a dry flask 
 and add 25 to 50 g of anhydrous sodium sulphate. Stopper the flask 
 and let stand with occasional:shaking at a temperature below 25° C. 
 until the water is completely removed from the ether solution, which 
 will be shown by the solution becoming perfectly clear above the 
 solid sodium sulphate. Decant this clear. solution, if necessary, 
 through a dry filter paper, into a dry 100 cc Erlenmeyer flask. Pass 
 a rapid current of dry air (pass through a CaCl, tower) into the mouth 
 of the Erlenmeyer flask and heat to a temperature below 75° C. on a 
 dry hot plate until the ether is entirely driven off. 
 ~ Norsz.—It is important to follow all of the details since ether generally containg 
 alcohol and after washing with water always contains water. It is very difficult 
 to remove water and alcohol by evaporation from fatty acids, but the washing 
 of the ether solution and subsequent drying with anhydrous sodium sulphate 
 removes both water and alcohol. Ether, in the absence of water and alcohol, 
 is easily removed from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a ct ec maredt 
 flask and examined at once. 
 
 (kh) Test ror Minera O1L AND OTHER UNSAPONIFIABLE Mat- 
 TER. —Place 10 drops of the anid acid ees in a 50 cc test sath add 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes 
 add 40 cc of water, and mix; a clear solution indicates that not more 
 than traces of unsaponifiable matter are present. If the solution is 
 not clear, the oil is not pure linseed oil. 
 
 (1) Ioptnzs Numper or Farry Acips.—Place a small quantity of 
 the fatty acids (g) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping from 0.09 to 0.15 g into a 500 ce 
 bottle having a well-ground glass stopper, or an Erlenmeyer flask 
 having a specially flanged neck for the iodine test. Reweigh the 
 burette or beaker and determine amount of sample used. Add 10 cc 
 of chloroform. Whirl the bottle to dissolve the sample. Add 10 ce 
 of chloroform to each of two empty bottles like that used for the sam- 
 ple. Add to each bottle 25 ce of the Wijs solution (see Reagents) and 
 let stand with occasional shaking for one hour in a dark place at a 
 temperature of from 21 to 23° C. Add 10 ce of the 15 per cent 
 potassium iodide solution and 100 ec of water, and titrate with 
 standard sodium thiosulphate, using starch as indicator. The titra- 
 tions on the two blank tests should agree within 0.1 cc. From the 
 difference between the average of the blank ‘titrations and the titra- 
 tion on the sample and the iodine value of the thiosulphate solution, 
 calculate the iodine number of the sample tested. (Jodine number 
 is centigrams of iodine to 1 g of sample.) If the iodine number is 
 less than 175, the oil does not meet the specification. 
 
 (j) Coarse ParrioLes AND Sxins.—Dry in an oven at 105 to 
 110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
 amount of semipaste containing 10 g of pigment (see 2 (f)), add 50 ce 
 of kerosene, mix thoroughly, and wash with kerosene through the 
 screen, breaking up all lumps but not grinding. After washing with 
 kerosene until all but the particles too coarse to pass the screen have 
 been washed through, wash all kerosene from the screen with ether 
 or petroleum ether, eat the screen for one sri ‘at eon to’ eats C., 
 cool, and weigh. ol 
 
 3. ANALYSIS OF PIGMENT: 
 
 (a) QuaLiTaTIvE ANALYsIs.—Make qualitative analysis following 
 ordinary methods. 
 
 (6) Loss on Ianit1ion.—Ilgnite 1 g of the pigment in a weighed 
 porcelain crucible until all carbon is consumed. It is best to use 
 gentle heat with free access of air. Cool, weigh, and ca‘culate 
 the percentage of loss on ignition. © 
 
 (c) CarBoN AND InsoLUBLE MinERaL Marerian.—Place 1 g of 
 the pigment in a porcelain dish, moisten with a few drops of alcohol, 
 add 20 cc of concentrated hydrochloric acid, cover, and heat on 
 steam bath for 15 minutes. Remove cover and evaporate to dryness, 
 moisten with hydrochloric acid, add 25 cc of water, filter on a 
 
 ~~ ee ee Pe eS zi 
 
 Ce. a ee ee ee ee Pe ey 
 
\ 
 
 SPECIFICATION FOR BLACK PAINT ‘f 
 
 weighed Gooch crucible, and wash with hot water until the washings 
 are free from lead and iron. Dry the crucible and contents at 
 105 to 110° ©. for 2 hours. Ignite for 7 minutes in a current of 
 dry carbon dioxide (using a Rose crucible cover) with a flame about 
 20 cm high. Cool in a current of dry carbon dioxide and weigh. 
 Then ignite with free access of air (or in a current of oxygen) until 
 all carbon is consumed. Cool and weigh. The loss in weight is: 
 calculated’ as carbon, and the residue remaining on the Gooch 
 crucible is calculated as insoluble mineral material. 
 
 (7) Leap Oxipze anp Iron Oxipe.—Determine lead and iron 
 in the filtrate from the carbon determination by any convenient 
 method, calculating lead:to Pb;O, and iron to Fe,O3;. 
 
 4, LABORATORY EXAMINATION—MIXED PAINT 
 
 (a) Caxine 1n Contariner.—Follow the procedure outlined in 
 2 (a), noting that the paint should be no more difficult to break up 
 than a good grade of mixed paint. 
 
 (b) Cotor.—Follow the procedure outlined in 2 (6). 
 
 (c) Weicur PER GALLoN.—Weigh a clean, dry, 100 cc graduated 
 flask. Fill to the mark with the thoroughly mixed paint and weigh 
 again. The increase in weight expressed in grams, divided by 100, 
 gives the specific gravity, which multiplied by 8.33 gives the weight 
 in pounds per gallon. 
 
 (2) BrusHING PRorERTIES AND Time oF Dryine.—Brush the 
 well-mixed paint on a suitable panel, which may be ground glass, 
 steel, or well-filled wood. Note whether the paint works satis- 
 factorily under the brush. Place the panel in a vertical position in 
 a well-ventilated room and let stand for 18 hours. The paint shall 
 be dry, smooth, and free from streaks. Flow a portion of the. paint 
 on a clean glass plate. Let dry in a nearly vertical position at room 
 temperature (65 to 100° F.).. The film shall show no streaking or 
 separation within a distance of 4 inches from the top. 
 
 (e) Water.—Mix 100 g of the paint in a 500 cc short ee glass 
 flask! with 75 cc of toluol (free from water). Connect with the dis- 
 tilling trap and condenser and heat so that the condensed distillate 
 falls from the end of the condenser at the rate of from two to five 
 drops per second. Continue the distillation at the specified rate 
 until no water is visible on any part of the apparatus except at the 
 bottom of the trap. This operation usually requires less than an 
 hour. A persistent ring of condensed water in the condenser tube 
 should be: removed by increasing the rate of distillation for a few 
 minutes. The number of cubic centimeters of condensed water 
 
 1 The apparatus for determining water is that described in ‘“‘Standard method of test for water in petro- 
 
 jeum products and other bituminous materials,’”’ Serial Designation D-95-24, A.S, T. M. Standards, 
 1924, p. 901 and Figure 1 (0) and (c), p. 902, 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 measured in the trap at room temperature is the percentage of water 
 in the paint. 
 
 (f) VotaTiLe THInNeR.—Follow the procedure outlined in 2 (e). 
 Correct the result for any water found (see 4 (e)) and report the 
 remainder as a volatile thinner. 
 
 (g) Percentacre or Picment.—Follow the procedure outlined in 
 2 
 
 (h) Testing NonvouatiLe VexHicite.—Follow the proéedure out- 
 lined in 2 (g), 2 (A), and 2 (2), except that in the preparation of the 
 fatty acids the mixture of paint and alkali is heated on the steam 
 bath until all yolatile thinner is driven off. 
 
 (1) Coarse ParticLes aND Sxins.—Follow the procedure out- 
 lined in 2 (9). 
 
 (7) Testing Piement.—Follow the Procedure outlined in 3 (a) 
 to 3 (d), inclusive. 
 
 5. REAGENTS 
 
 (a) Extraction Mrxturrt.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 
 4 volumes methyl alcohol. 
 
 1 volume acetone. 
 
 (6) Aquzous Soprum Hyproxipr.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 cc. } 
 
 (c) Stanparp Sopium TuHiosuLpHaTe SoLutTion.—Dissolve pure 
 sodium thiosulphate in distilled water (that has been well boiled 
 to free it from carbon dixoide) in the proportion of 24.83 g of crys- 
 talized sodium thiosulphate to 1,000 cc of the solution. It is best 
 to let ‘this sdlution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Treadwell -Hall, 
 Analytical Chemistry, vol. 2, 6th ed., p. 551.) This solution. will be 
 approximately decinormal, inl it is best to leave it as Ib is after 
 determining its exact iodine value, rather than to attempt to adj ust 
 it to exactly decinormal. Preserve in a stock bottle provided with 
 a guard tube filled with soda lime. 
 
 (d) Starcu So.ution.—Stir up 2 to 3 g of potato starch | or ‘5 g 
 of soluble starch with 100 cc of 1 per cent salicyclic acid solution, 
 add 300 to 400 cc boiling water, and boil the mixture until the starch 
 is practically dissolved, then dilute to 1 liter. 
 
 (e) PoTasstum Topipz SoLuTiIon.—Dissolve 150 g of ‘potassium 
 iodide free from iodate in distilled water and dilute to 1 ,000 cc. 
 
 (f) Wiss Sonution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine, or more particu- 
 
SPECIFICATION FOR BLACK PAINT 9 
 
 larly of chlorine over that required to form the monochloride. This 
 condition is most satisfactorily attained by dissolving in the whole 
 of the acetic acid to be used the requisite quantity of iodine, using 
 gentle heat to assist the solution, if it is found necessary. Dissolve 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° te: 
 and is free from reducing impurities in the proportion so that 13 g | 
 of iodine will be present in 1,000 cc of solution. Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the 
 remainder until the halogen content of the solution is doubled. 
 Ordinarily it will be found that by passing the chlorine into the 
 main part of the solution until the characteristic color of free iodine 
 has just been discharged there will be a slight excess of chlorine 
 which is corrected by the addition of the requisite amount of the 
 unchlorinated portion until all free chlorine has been destroyed. 
 A slight excess of iodine does little or no harm, but excess of chlorine 
 must be avoided. 
 
 (g) Auconotic Sopium HypRroxIpE SoLuTion.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
 Decant the clear liquid into another bottle and keep well stoppered. 
 This solution should be colorless or only slightly yellow when used, 
 and it will keep colorless longer if the alcohol is previously treated 
 with sodium hydroxide (about 80 g to 1,000 cc), kept at about 
 50° C. for 15 days, and then distilled. 
 
 VII. PACKING AND MARKING OF SHIPMENTS 
 
 Ci 
 
 Shall be in accordance with commercial practice unless otherwise 
 specified. | 
 VIII. NOTES 
 
 Black paint may be ordered in the form of either semipaste paint 
 or ready-mixed paint. The semipaste may be purchased by net 
 weight or by volume. The ready-mixed paint should be purchased 
 by volume (231 cubic inches to the gallon). 
 
 For formulas and methods of using this material and information 
 regarding the use of other specification paint materials see Bureau 
 of Standards Technologic Paper No. 274, entitled ‘Use of United 
 States Government Specification Paints and Paint Materials.” 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDEN1 OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. | 
 
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DEPARTMENT: OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, 
 
 No. 97. 
 
 [3d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 GREEN PAINT, SEMIPASTE AND READY MIXED. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 15. 
 
 This Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 
 Page 
 See ee ee eee ts Oe ats, Does OLR. Ae. at. I 
 Mk wy is wt ee ee vw wd letStay'y «Reb bolerg eres lddawe are wwlaieye * 
 ee eeeetgee @xaimitiation of semipaste: .... 2.6.6. ee eee eee teens 3 
 rear Ses rr rk BGI ee We de bu wR Ue eS Ges 6 
 Sauer y examination of mixed paint... ...... 0.06... ccc cece cee neeens 8 
 Ee Ey Ck cle kets dene sree cbocsheutecescuees 9 
 
 1. GENERAL. 
 
 The paint contemplated by this specification is a chrome green 
 paint, and it may be ordered either in the form of semipaste 
 pigment ground in linseed oil or as ready-mixed paint. 
 
 The basis of purchase may be either net weight or volume (231 
 cubic inches to the gallon). 
 
 (a) PicMENT.—The pigment in ath semipaste and ready- 
 mixed paints should be a chrome green containing about 23 per 
 
 109836°—22—1 
 
2 Circular of the Bureau of Standards 
 
 cent of color (sum of lead chromate and insoluble Prussian blue), 
 about ro per cent of magnesium silicate, aluminum silicate, or 
 similar siliceous material, and about 67 per cent of barium sul- 
 phate. It should be made by precipitating the color on the 
 proper base rather than by mixing the individual materials. It 
 must yield on analysis: 
 
 Maximum.| Minimum, 
 
 Per cent. Per cent. . 
 
 Color (total lead chromate and insoluble Prussian blue)... .........0.eeeees eee ee fener ees enese 20 
 Material soluble in water, including soluble Prussian blue.................-.-.- O27 li ticaknieers 
 Acid-soluble calcium in any form, calculated as CaO........22222.--ee nee eee ees Bio Sl Bn a 
 Material other than color and barium sulphate. ......... 0.00... cence seco ee erres a9 Saran 
 
 The remainder must be barium sulphate. 
 a le ee 
 
 (b) Liquip.—The liquid in semipaste paint shall be entirely 
 linseed oil; in ready-mixed paint it shall contain not less than 90) 
 per cent aioe oil, the balance to be combined drier and thinner. 
 The thinner shall be turpentine, volatile mineral spirits, or a 
 mixture thereof. 
 
 (c) SEMrpasTtE.—Semipaste paint shall be made by thoroughly 
 grinding the pigment with linseed oil. | 
 
 The semipaste as received and three months thereafter shall be 
 not caked in the container and shall break.up readily in.linseed 
 oil to form a smooth paint of brushing consistency. It shall.mix 
 readily with linseed oil, turpentine, or volatile mineral spirits, or 
 any combination of these substances, in all proportions, without 
 curdling. ‘The color and hiding power when specified shall be 
 equal to that of a sample mutually agreed upon by buyer and 
 seller. The weight per gallon shall be not less than 16 mina 
 The paste shall consist of: 
 
 Per cent. Per cent. 
 Pigment noes ow bs hie vin pein 4.9 a iple. 09 010 0 0 gh bp copay pereealle naire 1a le laters ee 72 68 
 
 Linseed ob... ccs oc ccc a boc vice suis nialiicie «cmttele O Ie DA: IOk MeBeGM ab Ae tena eisai’ 32 28 
 
 Moisture and other volatile matter... fis ccuccccenrenes segs oe eeeee ener OT Aessaaao cna 
 
 Coarse particles and ‘‘skins”’ (total residue retained on No. 325 screen based on ' ead 
 pigmen: t) Poe em ree eee HoH EH ERE HH EHH OHHH TEES ETOH OHH SEHR HEHEHE HS TEE HE HD eee rer eee ere > 4 }25 & Re. -  a 
 
 (d) Reapy-Mrxep Parnt.—Ready-mixed paint shall; be» well 
 ground, shall not settle badly or cake in the container, shall be 
 readily broken up with a paddle to a smooth uniform paint of good 
 brushing consistency, and shall dry within 18 hours to a full oil 
 gloss, without streaking, running, or sagging. The ‘color and 
 hiding power when specified shall be equal to those of a sample 
 
Specification for Green Patnt 3 
 
 mutually. agreed upon by buyer and seller. The weight per gallon 
 shall be not less than 12 pounds. ‘The paint shall consist of: 
 
 Maximum.| Minimum. 
 
 Percent. | Percent. 
 Pigm 55 50 
 
 CC ee 
 
 Liguia ( ‘eighties at least 90 per cent linseed oil)... 0.00. lee cee wees 50 : 45 
 
 aa aN ET Ue SE aac 5 cites oy'2)4 AL. A/a ale. dibveig le ayals: bv 0 die ol ewe cd ape oO Vio alan EE a aap oe 
 
 Coarse particles and ‘‘skins’’ (total residue retained on No. 325 screen based on 
 i ac Gio dis dm a pieige ng 5 ve MA cleus $x oe raddee engin te hl eee ieee 
 
 Note.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
 reserves the right to use any additional available information to ascertain whether the material meets 
 
 _ the specification. 
 2. SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1000 packages shall be taken 
 as representative of the whole. Whenever possible an original 
 unopened container shall be sent to the laboratory, and when this 
 is for any reason not done, the inspector shall determine by thorough 
 testing with a paddle or spatula whether the material meets the 
 requirement regarding caking in the container. He shall then 
 -thoroughly mix the contents of the container and draw a sample 
 of not less than 5 pounds. ‘This sample shall be placed in a clean, 
 dry metal or glass container, which it must nearly fill. The con- 
 tainer shall be closed with a tight cover, sealed, marked, and sent 
 to the laboratory for test with the inspector’s report on caking. 
 
 When requested, a duplicate sample may be taken from the 
 same package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 RA LABORAT ORY EXAMINATION OF SEMIPASTE. 
 
 (a) CAKING IN CONTAINER. — When an original package is 
 ‘received in the laboratory it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. ‘The paste must be no more diffi- 
 cult to break up than a normal good grade of semipaste paint. 
 The semipaste shall finally be thoroughly mixed, removed from 
 the container, and the container wiped clean and weighed. This 
 weight subtracted from the weight of the original package gives 
 the net weight of the contents. A portion of thoroughly mixed 
 semipaste shall be placed in a clean container and the portions 
 for the remaining tests promptly weighed out. 
 
 (b) CoLtor.—Place some of the paint on a clean, clear glass 
 plate. Place some of the standard agreed upon beside the sample 
 on the plate, turn the glass over, and compare the colors. 
 
4 | Circular of the Bureau of Standards 
 
 (c) WEIGHT PER GALLON.—From the weight of a known volume 
 of the paste calculate the specific gravity, which multiplied by 
 8.33 gives the weight in pounds per gallon. Any suitable con- 
 tainer of known volume may be used for the purpose, but a short 
 cylinder of heavy glass with rounded bottom about 75 mm high ° 
 and having a capacity of from 125 to 175 cc (a glass cap to keep 
 dust from reagent bottle stopper) is a convenient apparatus for 
 the purpose. ‘The capacity of this vessel is determined to within 
 1 cc. The paste is packed into it until completely full, the top 
 leveled off smooth with a spatula, and weighed to +0.5 g. Sub- 
 tract the weight of the empty container and divide the remainder 
 by the number of cubic centimeters representing the capacity of 
 the container. The quotient is the specific gravity, which can be 
 thus determined within +2 in the second decimal place. 
 
 (d) Mrxinc wit LinskED O1.—One hundred grams of the 
 paste shall be placed in a cup, 30 cc of linseed oil added slowly with 
 careful stirring and mixing with a spatula or paddle. ‘The result- 
 ing mixture must be smooth and of good brushing consistency. 
 
 (e) MotstrurE AND OTHER VOLATILE Matrer. — Weigh accu- 
 rately from 3 to 5 g of the paste into a tared flat-bottomed dish 
 about 8 cm in diameter, spreading the paste over the bottom. 
 Heat at 105 to 110° C, for three hours, cool, and weigh. Calculate 
 loss in weight as percentage of moisture and volatile matter. 
 
 ({) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 ¢ 
 of.the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
 ‘extraction mixture” (see reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add 
 sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm 
 with a similar tube or a tube with water. Whirl at a moderate 
 speed until well settled. Decant the clear supernatant liquid. 
 Repeat the extraction twice with 40 cc of extraction mixture and 
 once with 40 ce of ether. After drawing off the ether, set the 
 tube in a beaker of water at about 80° C. or on top of a warm oven 
 for 10 minutes, then in an oven at 105 to 110° C. for two hours. 
 Cool, weigh, and calculate the percentage of pigment. Grind 
 the pigment to a fine powder, pass through a No. 80 screen to 
 remove any skins, and preserve in a stoppered bottle. 
 
 (g) PREPARATION OF Farry Acimps.—To about 25 g of the 
 paste in a porcelain casserole, add 15 cc of aqueous sodium 
 
Specification for Green Paint 5 
 
 hydroxide (see reagents) and 75 cc of ethyl alcohol, mix and 
 heat uncovered on a steam bath until saponification is complete 
 (about one hour). Add 100 cc of water, boil, add sulphuric 
 acid of ‘specific gravity 1.2 (8 to 10 ce in excess), boil, stir, and 
 transfer to a separatory funnel to which some water has been 
 previously added. Draw off as much as possible of the acid 
 aqueous layer, wash once with water, then add 50 cc of water 
 and 50 cc of ether. Shake very gently with a whirling motion 
 to dissolve the fatty acids in the ether, but not so violently as 
 to form an emulsion. Draw off the aqueous layer and wash 
 the ether layer with one 15 cc portion of water and then with 
 5 ce portions of ‘water until! free from sulphuric acid. Then 
 draw off the water layer completely. Transfer the ether solution 
 to a dry flask and add 25 to 50 g anhydrous sodium sulphate. 
 Stopper the flask and let stand with occasional shaking at a 
 temperature below 25° C. until the water is completely removed 
 from ‘the ether solution, which will be shown by the solution 
 becoming perfectly clear above the solid sodium sulphate. Decant 
 this clear solution, if necessary, through a dry filter paper, into 
 a dry roo cc Erlenmeyer flask. Pass a rapid current of dry air 
 (pass through a CaCl, tower) into the mouth of the Erlenmeyer 
 flask and heat to a temperature below 75° C. on a dry, hot plate 
 until the ether is entirely driven off. ; 
 
 NoTe.—It is important to follow all of the details, since ether generally contains 
 alcohol and after washing with water always contains water. It is very difficult 
 to remove water and alcohol by evaporation from fatty acids, but the washing of the 
 ether solution and subsequent drying with anhydrous sodium sulphate removes both 
 water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
 from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (hk) Test FoR MINERAL OIL AND OTHER UNSAPONIFIABLE 
 Marter.—Place 10 drops of the fatty acids (g) in a 50 cc test 
 tube, add 5 cc of alcoholic soda (see Reagents), boil vigorously 
 for five minutes, add 40 cc of water, and mix; a clear solution 
 indicates that not more than traces of unsaponifiable matter are 
 present. If the solution is not clear, the oil is not pure linseed oil. 
 
 (4) IopIne NuMBER OF Farry Acips.—Place a small quantity of 
 the fatty acids (g) in a small weighing burette or beaker. Weigh 
 accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
 into a 500 cc bottle having a well-ground glass stopper, or an 
 Erlenmeyer flask having a specially flanged neck for the iodine 
 
 109836 °—22——-2 
 
6 Circular of the Bureau of Standards 
 
 test. Reweigh the burette or beaker and determine amount of 
 sample used. Add 10 cc of chloroform. Whirl the bottle to 
 dissolve the sample. Add io cc of chloroform to two empty bot- 
 tles like that used for the sample. Add to each bottle 25 ce of 
 the Hanus solution (see reagents) and let stand with occasional 
 shaking for one-half hour. Add 10 ec of the 15 per cent potas- 
 sium iodide solution and 100 ce of water, and titrate with stand- 
 ard sodium thiosulphate, using starch as indicator. The titrations 
 on the two blank tests should agree within o.1 ce. From the 
 difference between the average of the blank titrations and: the 
 titration on the sample and the iodine value of the thiosulphate 
 solution, calculate the iodine number of the sample tested. (Io- 
 dine number is centigrams of iodine to 1 g of sample.) If the - 
 iodine number is less than 170, the oil does not meet the specifica- 
 tion. im teehee 
 (7) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
 110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
 amount of semipaste containing 10 g of pigment. (see 3 (/)), add 
 50 cc of kerosene, mix thoroughly, and wash with kerosene 
 through the screen, breaking up all lumps but not grinding. After 
 washing with kerosene until all but the particles too coarse to pass 
 the screen have been washed through, wash all kerosene from the 
 screen with ether or petroleum ether, heat the screen for one hour 
 at 105 to 110° C., cool, and weigh. 
 
 4. ANALYSIS OF PIGMENT. 
 
 (a) QUALITATIVE ANALYsIS.—Test for Prussian blue by boiling a 
 portion of the pigment with sodium hydroxide solution. A yellow 
 or yellow-brown precipitate with a yellow liquid above it should 
 result. Filter, add a mixture of ferric and ferrous salts to the 
 filtrate, and render acid with dilute hydrochloric acid. A blue 
 color indicates Prussian blue in the sample. Ignite another por- 
 tion very gently to decompose the Prussian blue and make a 
 qualitative analysis of the residue. 
 
 (b) MaTteR SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
 ment to a graduated 250 cc flask, add 100 ce of water, boil for 
 5 minutes, cool, fill to mark with water, mix, and allow to settle. 
 Pour the supernatant liquid through a dry paper and discard the 
 first 20 ec. Then evaporate too cc of the clear filtrate to dryness 
 in a weighed dish, heat for one hour at 105 to 110° C., cool, and 
 weigh. 
 
Specification for Green Paint 7 
 
 (c) BARIUM SULPHATE AND SILICEOUS MATERIAL.—Heat a 1 g 
 portion of the pigment very gently in a small porcelain dish. 
 The heat must be so regulated by moving the burner that the 
 Prussian blue is thoroughly decomposed without rendering the 
 iron difficultly soluble. Allow to cool, transfer to a 400 cc beaker, 
 add 20 cc of concentrated hydrochloric acid, heat on steam bath 
 for 30 minutes, boil for 5 minutes, dilute with hot water to about 
 250 ce, filter on paper while hot, wash thoroughly with hot water 
 until the washings are free from lead and chlorine, and ignite and 
 weigh the residue, which will be barium sulphate and siliceous 
 material. Mix the ignited residue with about 10 times its weight 
 of anhydrous sodium carbonate (grinding the mixture in an agate 
 mortar if necessary), and fuse the mixture in a covered platinum 
 crucible, heating about one hour. Let cool, place crucible and 
 cover in a 250 cc beaker, add about 100 cc of water, and heat 
 until the melt is disintegrated. Filter on paper (leaving crucible 
 and cover in beaker) and wash the beaker and filter thoroughly 
 with hot water to remove soluble sulphates. Place the beaker 
 containing the crucible and cover under the funnel, pierce the 
 filter with a glass rod, and wash the carbonate residue into the 
 beaker by means of a jet of hot water. Wash the paper with hot, 
 dilute hydrochloric acid (1:1), and then with hot water. If the 
 carbonate residue is not completely dissolved, add sufficient dilute 
 hydrochloric acid to effect solution, and remove crucible and cover, 
 washing them with a jet of water. Heat the solution to boiling 
 and add ro to 15 cc of dilute sulphuric acid, and continue the 
 boiling for 10 or 15 minutes longer. Let the precipitate settle, 
 filter on a weighed Gooch crucible, wash with hot water, ignite, 
 cool, and weigh as BaSO,. Subtract from the result of the 
 previous determination to obtain the siliceous material. 
 
 (d) [wap AND CHROMIUM.—Unite the filtrate and washings 
 from barium sulphate and siliceous material (see (c)), dilute to 
 soo cc, neatly neutralize with ammonium hydroxide, and pass 
 in a rapid stream of hydrogen sulphide until all the lead is pre- 
 cipitated as PbS; filter, wash with water containing a little hydro- 
 gen sulphide, dissolve in hot nitric acid (1:3), and determine lead 
 as sulphate in usual manner, weighing as PbSQ,. Boil the fil- 
 trate from the lead sulphide to expel hydrogen sulphide. Add 
 sodium peroxide in sufficient amount to render the solution: alka- 
 line and to oxidize the chromium to chromate. Boil until the 
 hydrogen peroxide is driven off, cool, acidify with sulphuric acid 
 
8 Circular of the Bureau of Standards 
 
 (1:4), add a measured excess of a freshly prepared solution of 
 ferrous sulphate, and titrate the excess of ferrous iron with stand- 
 ard potassium dichromate, using potassium ferricyanide solution 
 as outside indicator. ‘Titrate a blank of an equal volume of the 
 ferrous sulphate solution with the standard potassium dichromate. 
 From the difference between the titration on the blank and on 
 the sample, calculate the chromium in the sample to PbCrO,,. 
 From the PbCrO, found, calculate the equivalent of PbSO, by 
 multiplying by the factor 0.938. Subtract this value from the 
 -total PbSO, found above and report the remainder as lead com- 
 pounds other than chromate, calculated as PbSO,.” |” | 
 
 (ce) Catcrum.—Ignite 2 g of the pigment’ and dissolve the 
 residue in hydrochloric acid as in 4(c). Then, without filtering 
 from the insoluble matter, transfer to a 500 éc volumettic flask, 
 saturate with hydrogen sulphide, make alkaline with ammonia, 
 fill to the mark, mix, and filter through a dry paper, discarding 
 the first 20 cc. Then determine the calcium in 250 ce of the 
 filtrate (corresponding to 1 g pigment) by precipitztion as oxalate 
 and weighing as calcium oxide. 
 
 (f) Cotor.—Add the percentages of matter Sitti in wate 
 4(b), barium sulphate and siliceous material 4(c), lead compounds 
 other than chromate calculated as PbSO, 4(d); and calcium oxide 
 4(e) and subtract the sum from roo. Call the tei shirt ite the 
 percentage of color. 
 
 5, LABORATORY EXAMINATION OF MIXED volt ania 
 
 (2) CAKING IN CoNTAINER.—Follow the procedure outlined in 
 3(a), noting that the paint should be no more Hisiteso to eee ny 
 than a good grade of mixed paint. | . 109 
 
 (b) CoLor.—Follow the procedure outineds in 3(6). : 
 
 (c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 ec gradu- 
 ated flask. Fill to the mark with the thoroughly mixed paint and 
 weigh again. ‘The increase in weight expressed in grams, divided 
 by 100, gives the specific gravity, which eras by 8. “33 hag 
 the weight in pounds per gallon. 
 
 (dq) BRUSHING PROPERTIES AND TIME OF DRYING. soiBaiaa the 
 well-mixed paint on a suitable panel, which may be ground glass, 
 steel, or well-filled wood. Note whether the paint works satis- 
 factorily under the brush. Place the panel in a vertical position 
 
 in a well-ventilated room and let stand for 18 hours. The paint 
 
 should be dry and free from streaks. Flow a portion of the paint 
 on a clean glass plate. Let dry in a nearly vertical position at 
 
 { 
 bh 
 : 
 | 
 
Specification for Green Paint 9 
 
 room temperature (65 to 100° F). ‘The film shall show no 
 streaking or separation within a distance of 4 inches from the top. 
 
 (ec) WATER.—Mix 100 g of the paint in a 300 cc flask with 75 cc 
 of toluol. Connect with a condenser and distill until about 50 cc 
 of distillate has been collected in a graduate. ‘The temperature in 
 the flask should be then about 105° to 110° C. ‘The number of 
 cubic centimeters of water collecting under the toluol in the re- 
 ceiver is the percentage of water in the paint. 
 
 (f) VOLATILE THINNER.—Follow the procedure outlined in 
 3(e). Correct the result for any water found (see 5(e)) and report 
 the remainder as volatile thinner. 
 
 (9) PERCENTAGE OF PiGMENT.—Follow the procedure outlined 
 in 3(7). 
 
 (h) TestInc NONVOLATILE VEHICLE.—Follow the procedure 
 outlined in 3(g), 3(h), and 3(z), except that in the preparation of 
 the fatty acids the mixture of paint and alkali is heated on the 
 steam bath until all volatile thinner is driven off. 
 
 (i) COARSE PARTICLES AND SKINS.—Follow the procedure out- 
 lined in 3(). 
 
 (j) Testinc PicMEN?T.—Follow the procedure outlined in 4(a) 
 to 4(e), inclusive. 
 
 6. REAGENTS. 
 
 (a) EXTRACTION MIXTURE.— 
 | 5 volumes benzol. 
 4 volumes methyl alcohol 
 1 volume acetone. , 
 (b) AguEous Soprum HyproxipE.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 ~ (ce) STANDARD SODIUM THIOSULPHATE SOLUTION.— Dissolve pure 
 sodium thiosulphate in distilled water (that has been well boiled 
 to free it from carbon dioxide) in the proportion of 24.83 g crys- 
 tallized sodium thiosulphate to 1,000 cc of the solution. It is 
 best to let this solution stand for about two weeks before stan- 
 dardizitig. Standardize with pure resublimed iodine. (See Tread- 
 well-Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This so- 
 lution will be approximately decinormal, and it is best to leave 
 it as it is after determining its exact iodine value, rather than to 
 attempt to adjust it to exactly decinormal. Preserve in a stock 
 bottle provided with a guard tube filled with soda lime. 
 (d) Starcu SOLUTION.—Stir up to 2 to 3 g of potato starch or 
 5 g of soluble starch with 100 ce of 1 per cent salicylic acid solu- 
 
10 Circular of the Bureau of Standards 
 
 tion, add 300 to 400 cc boiling water, and boil the mixture until 
 the starch is practically dissolved, then dilute to r liter. | 
 
 (e) Potassium IopiDE So_uTION.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 ce. 
 
 ({) HANUS, SOLUTION.—Dissolve 13.2 g of iodine im 1,000 ec 
 of 99.5 per cent glacial acetic acid, which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, deter- 
 mined by titration (3 cc of bromine is about the proper amount). 
 The iodine may be dissolved by the aid of heat, but the solution 
 should be cold when the bromine is added. 
 
 (g) ALcoHoLtic Soprum Hyproxie SoLuTION.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
 of about 22 g per 1,o00cc. Let stand in a stoppered bottle. 
 Decant the clear liquid into another bottle and keep well stop- 
 pered. This solution should be colorless or only slightly yellow 
 when used, and it will keep colorless longer if the alcohol is pre- 
 viously treated with sodium hydroxide (about 80 ¢ to 1,006' ee), 
 kept at about 50° C. for 15 days, and then distilled. 
 
 (hk) STANDARD FERROUS SULPHATE SOLUTION.— Dissolve 14 g of 
 pure crystallized ferrous sulphate (FeSO, 7H,O) in about 500 cc 
 of water, to which 25 cc of concentrated H,SO, has been added, 
 and then dilute to 1,000 cc. This solution should be freshly 
 standardized when needed, as it does not keep well. 
 
 (1) STANDARD PoTAssiIuM DICHROMATE SOLUTION.—Dissolve 
 4.903 g of pure dry crystallized potassium dichromate in water 
 and dilute to 1,000 cc. One cubic centimeter of this solution 
 corresponds to 0.0108 g° PbCrO,, or o.o101 g PbSO,,. 
 
 (j) PotasstuM FERRICYANIDE SOLUTION.—Dissolve a piece half 
 as big as a small pea in 50 ce of water. This solution must be 
 made fresh when wanted, because it does not keep. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 AT 
 
 5 CENTS PER COPY 
 V 
 
 4 i 
 
 WASHINGTON : GOVERNMENT PRINTING OFFICH : 1922 
 
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 Tis t bed 
 
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DEPARTMENT OF COMMERCE, 
 BUREAU OF STANDARDS. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 No. 98. 
 
 [Second edition. Issued February 28, 1923.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 VOLATILE MINERAL SPIRITS FOR THINNING PAINTS.’ 
 
 FEDERAL SPECIFICATIONS BOARD. 
 
 STANDARD SPECIFICATION No. 16. 
 ’ [Revised seciete 2, 1923.] 
 
 This specification was officially adopted by the Federal Specifications Board 
 on February 3, 1922, for the use of’ the departments and independent establish- 
 ments of the Government in the purchase of volatile mineral spirits for thin- 
 ning paints. 
 
 CONTENTS. 
 
 Page. 
 ON SE eer en rar rte eee Tees eee eG I 
 2. Detection and removal of separated water. ..........-- +s sere esse eee e eens 2 
 @. Baap), 1.01 20 ES. OM LNT OR, BQ TIOO, AE ood e, AEP es 2 
 4. Laboratory examination...........-. lhermo. ive. dormcrery Leela - bree: tp 8 
 ge. Wags OF DULAC. orem ty he rte yt Ati biaee Fi beta aa? 9 
 
 1. GENERAL. 
 
 This specification applies only to petroleum distillates, known 
 as mineral spirits. The material delivered under this specifica- 
 tion shall conform to the following requirements: 
 
 APPEARANCE.—Shall be cleat and free from suspended matter 
 and water. | 
 
 CoLor.—Shall be no darker than an aqueous solution of potas- 
 sium dichromate containing 0.0048 g per liter (this corresponds to 
 No. 21 Saybolt chromometer). 
 
 Spot ‘Test.—Shall evaporate completely from filter paper. 
 
 1 The mineral spirits called for in this specification is the same as that called for in Specifications for 
 
 Petroleum Products, Bureau of Mines Technical Paper 323. 
 27818°—23 
 
2 Circular of the Bureau of Standards. 
 
 FLASH Pornt.—Shall be not lower than 30° C. (86° F.) when 
 tested in a closed cup tester. 
 
 BLACKENING.—Shall not blacken clean metallic copper. 
 
 DisTILLATION.— Distillate below 130° C) (266° F.) shall not 
 exceed 5 per cent. Distillate below 230° C. (446° F.) shall be 
 not less than 97 per cent. 
 
 Acrpity.—Shall be neutral. 
 
 2. DETECTION AND REMOVAL.-OF SEPARATED WATER. 
 
 Draw a portion by means of a glass or metal container with a 
 removable stopper or top, or with a ‘‘thief,’’ from the lowest part 
 of the container, or by opening the bottom valve of the perfectly 
 level tank car. If water is found to be present, draw it all out, 
 record the quantity, and deduct it from the total volume of liquid 
 delivered. 
 
 Note.—Deliveries will in general be sampled and tested by the following methods, 
 
 but the purchaser reserves the right to use any additional available information to 
 ascertain whether the material meets the specification. 
 
 3. SAMPLING. 
 
 The method of sampling given under (a) should be used when- 
 ever feasible. When method (a) is not applicable, method (6), 
 
 (c), or (d) is to be used, pasa to the special conditions that ~ 
 
 obtain. 
 
 (a) WHILE LOADING TANK Cap OR WHILE FILLING Comtanaes 
 FOR SHIPMENT.—Samples shall be drawn by the purchaser’ s 
 inspector at the discharge pipe where it enters the Teceiving 
 vessel or vessels. The composite sample shall be not less than 5 
 gallons and shall consist of small portions of not more than 1 
 quart each taken at regular intervals during the entire period of 
 loading or filling. The composite sample thus obtained shall be 
 
 thoroughly mixed, and from it three samples of not less than 1 _ 
 
 quart each shall be placed in clean, dry glass bottles or tin cans, 
 which must be nearly filled with the sample and securely stoppered 
 with new clean corks or well-fitting covers or caps. ‘These shall 
 be sealed and distinctly labeled by the inspector. One shall be 
 delivered to the buyer, one to the seller, and the third held for 
 check in case of dispute. 
 
 (6) From LoapEp Tank CAR OR OTHER LARGE VESSEL. —The 
 composite sample taken shall be not less than 5 gallons and shall 
 consist of numerous small samples of not more than 1 quart each 
 
 taken from the top, bottom, and intermediate points by means — 
 
 of a metal or glass container with removable stopper or top. 
 
Specification for Mineral Spirits. 3 
 
 This device attached to a suitable pole is lowered to the various 
 desired depths, when the stopper or top is removed and the con- 
 tainer allowed to fill. The sample thus obtained is handled as 
 in (a). 
 
 (c) BARRELS AND Drums.—Barrels and drums shall be sampled 
 after gauging contents. Five per cent of the packages in any 
 shipment or delivery shall be represented in the sample. ‘Thor- 
 oughly mix the contents of each barrel to be sampled by stirring 
 with a clean rod and withdraw a portion from about the center 
 by means of a ‘‘thief’’ or other sampling device. The com- 
 posite sample thus obtained shall be not less than 3 quarts, shall 
 consist of equal portions of not less than one-half pint from each 
 package sampled, and shall be handled as in (a). Should the 
 inspector suspect adulteration, he shall draw the samples from 
 the suspected packages. 
 
 (d) SMALL CONTAINERS, CANS, ETC., OF 10 GALLONS OR LESS.— 
 These should be sampled, while filling, by method (a) whenever 
 possible; but in case this is impossible, the composite sample 
 taken shall be not less than 3 quarts. This shall be drawn from 
 at least five packages (from all when fewer), and in no case from 
 less than 2 per cent of the packages. The composite sample 
 thus taken shall be thoroughly mixed and subdivided as in (a). 
 
 4. LABORATORY EXAMINATION. 
 
 (a) APPEARANCE.—Examine to determine compliance with the 
 specification. 
 
 ‘(b) Coror.—Compare in any suitable apparatus the depth of 
 color of the sample with the depth of color of a fresh solution of 
 potassium dichromate in distilled water containing 0.0048 g K,Cr,O, 
 per liter. (If desired, the color may be determined in a Saybolt 
 chromometer, in which case the color must be no darker than » 
 No. 21 on that scale.) 
 
 (c) Spot Test.—Transfer five drops of the mineral spirits by 
 means of a small pipette or burette to the center of a clean white 
 filter paper supported on a 7-cm crystallizing dish and allow the 
 liquid to evaporate at room temperature, away from direct sun- 
 light. ‘There should be no oily spot left after 30 minutes. 
 
 (d) FLasuH Pornt.—Determine with either the ‘Tag”’ or Elliott 
 closed-cup tester. The former ‘is preferred.’ 
 
 2 Directions for using the “‘T'ag’’ tester may be found in A. S. T. M. Standards Ds6-21 and in Bureau 
 of Mines Technical Paper No. 323. Directionsfor using the Elliott cup may be found in Proceedings 
 A.S. T. M., 1917, pt. 1, p. 414. 
 
4 Circular of the Bureau of Standards. 
 
 (e) BLACKENING.—Place a clean strip of mechanically polished 
 pure sheet copper, about 14 inch wide and 3 inches long (1.3 em 
 by 7.5 cm) in a glass test tube about 34 inch wide and 18 inches 
 long (1.9 by 46 cm). Add sufficient of the sample to be tested to 
 completely cover the strip and heat rapidly to boiling (it is most 
 convenient to heat the tube by immersion in an oil bath main- ~ 
 tained at a temperature slightly higher than the initial boiling 
 point of the mineral spirits): Keep the sample boiling, without any 
 actual distillation taking place, for 30 minutes and then examine 
 the copper strip for blackening. A slight tarnish shall be disre- 
 garded, but any marked blackening shall be cause for rejection. 
 
 ({) DisTILLATION.—Use the A. S. T. M. (D 86-21 T) method 
 as described below, except that it will be necessary to read the 
 volume of the distillate at 130° C. and at 230° C. and the distilla- 
 tion need not be carried beyond the 230° C. (446° F.) point. 
 
 APPARATUS. 
 
 Flask.—The standard 100 cc Engler flask is shown in aoe I, 
 the dimensions and allowable tolerance being as follows: 7 
 
 Dimensions of Engler flask. 
 
 Centi- 
 Description. Inches. 
 | meters. (cm) 
 Diameter of bulb, outside.) 05) 25. 3k ce Ae ee eee 6.5 2.56 0.2 
 Diameter of neck, Side ld. FRITS. A. See 1.6 - 63 Pa 
 Length of neck (7 2.022 hod set SSeS ee eee 15.0 5.91 4 
 Length of vapor tube 3.553 ec aiss'coedoSevsn ds eee ee ee 10. 0 3.94 x8 
 Diameter of vapor tube, outside............0. 0... c ec cece cece ce eecseceeveres -6 24 | . 05 
 Diameter of vapor firbe, inside.: :< 66543. jie dee nike. ede bs » tom 2 Sade ‘E72 4 16 a!) 
 Thickness of vapor tube wall. 0 v2.0%, «cs sess b nurse tren tesa bios he ear een ib . 04 -05 
 
 The position of the vapor tube shall be 9 cm (3.55 inches) 
 +3 mm above the surface of the liquid when the flask contains 
 its charge of 100 cc. The tube is opp Oates in the middle 
 of the neck and set at an angle of 75° (tolerance £3°) wash the 
 vertical. 
 
 Condenser.—The condenser (Fig. 2) consists of a 9/16 inch 
 OD No. 20 Stubbs gauge seamless brass tube 22 inches long. 
 It is set at an angle of 75° from the perpendicular and is 
 surrounded with a cooling bath 15 inches long, approximately 
 4 inches wide by 6 inches high. The lower end of the condenser 
 tube is cut off at an acute angle and curved downward for a length 
 of 3 inches and slightly backward, so as to insure contact with 
 
Specification. for Mineral Spirits. 5 
 
 the wall of the graduate at a point 1 to 114 inches below the top 
 of the graduate when it is in position to receive the distillate. 
 Shield.—The shield (Fig. 2) is made of approximately 22- 
 gauge sheet metal and is 19 inches high, 11 inches long, and 8 inches 
 wide, with a door on one narrow side, with two openings, 1 inch in 
 
 S 0.63" | Inside (Not outside) 
 ae % LECH 
 Ss 
 as 
 ' Sapreeemer +e 
 -O Se ae 
 yf Ad a / 
 + = % 
 aE s 
 ry ON 
 
 eee ee Level of liguid surface when 
 tlask conjains too CC 
 
 SEE 
 COCM 
 Outside 
 
 Fic. 1.— Standard 100 cc Engler flask for use in making distillation tests. 
 
 diameter, equally spaced, in each of the two narrow sides, and 
 with a slot cut in one side for the vapor tube. The centers of these 
 four openings are 814 inches below the top of the shield. There are 
 also three 14-inch holes in each of the four sides, with their centers 
 1 inch above the base of the shield. 
 
 Ring support and hard asbestos boards —The ring support is of 
 the ordinary laboratory type, 4 inches or larger in diameter, and 1s 
 
 27818°—23-——2 
 
6 Circular of the Bureau of Standards. 
 
 supported on a stand inside the shield. There are two hard 
 asbestos boards, one 6 by 6 by % inch, with a hole 1% inches in 
 diameter in its center, the sides of which shall be perpendicular to 
 the surface; the other, an asbestos board to fit tightly inside the 
 shield, with an opening 4 inches in diameter concentric with the 
 ring support. These are arranged as follows: The second asbestos 
 board is placed on the ring and the first or smaller asbestos board 
 on top, so that it may be moved in accordance with the directions 
 for placing the distilling flask. Direct heat is applied to the flask 
 only through the 1 14-inch opening in the first asbestos board. 
 
 lee Water Bath 
 2" Outside Diameter 
 
 ~~~ No. 2. 20 Gage Seamless 
 ie => Brass Tubing 
 
 ~ 
 OP ie, ~ 
 ~ ~~ « 
 
 am 
 
 Fic. 2.—Distillation outfit (A. S. T. M.) arranged for use of gas burner. 
 
 Gas burner or eleciric heater—Gas burner: The burner is so 
 constructed that sufficient heat can be obtained to distill the 
 product at the uniform rate specified below. ‘The flame should 
 never be so large that it spreads over a circle of diameter greater 
 than 3 %4 inches on the under surface of the asbestos board. A sen- 
 sitive regulating valve is a necessary adjunct, as it gives phen 
 control of heating. 
 
 Electric heater: The electric heater, which may be used in 
 place of the gas flame, shall be capable of bringing over ‘the first 
 
 drop within the time specified below when started cold and of con-- 
 
 tinuing the distillation at the uniform rate. ‘The electric heater 
 
Specification for Mineral Spirits. 7 
 
 shall be fitted with an asbestos board top % to 14 inch thick, having 
 a hole 134 inches in diameter in the center. When an electric 
 heater is employed, the portion of the shield above the asbestos 
 board shall be the same as with the gas burner, but the part below 
 may be omitted. 
 
 Thermometer.—A. S. T. M. high-distillation thermometer shall 
 conform to the following specifications: 
 
 Type: Etched stem glass. 
 
 Total length: 381 mm. 
 
 Stem: Plain front, enamel back, suitable thermometer tubing; diameter, 6 to 7 mm. 
 
 Bulb; Corning normal, Jena 16 III, or equally suitable thermometric glass; length, 
 to to 15 mm; diameter, 5 to 6 mm. 
 
 Actuating liquid: Mercury. 
 
 Range: 30 to 760° F., or o to 400° C. 
 
 Immersion: Total. 
 
 Distance to 30° F., or 0° C. mark from bottom of bulb: 25 to 35 mm. 
 
 Distance to 760° F., or goo® C. mark from top of tube: 30 to 45 mm. 
 
 Filled: Nitrogen gas. 
 
 Top finish: Glass ring. 
 
 Graduation: All lines, figures, and letters clear cut and distinct; scale graduated 
 in 2° F. or 1° C. divisions and numbered every 20° F. or 10° C., the first and each 
 succeeding 10° F. (5° C.) to be longer than the others. 
 
 Special markings: A. S. T. M. High Distillation, serial number, and manufacturer’s 
 name or trade-mark etched on the stem. 
 
 Accuracy: Error at any point on scale shall not exceed one smallest scale division 
 up to 700° F. or 370° C. 
 
 Tests for permanency of range: After being subjected to a temperature of 700° F. 
 or 370° C. for 24 hours the accuracy shall be within the limit specified. 
 
 ~ Points to be tested for certification: 32°, 212°, 400°, 700° F. or 0°, 100°, 200°, 370° C. 
 7 37 
 
 Graduate.—The graduate shall be of the cylindrical type, of 
 uniform diameter, with a pressed or molded base and a lipped 
 top. The cylinder shall be graduated to contain 100 cc and the 
 graduated portion shall be not less than 7 inches nor more than 
 8 inches long. It shall be graduated in single cubic centimeters, 
 and each fifth mark shall be distinguished by alonger line. It shall 
 be numbered from the bottom up at intervals of 10 cc. The dis- 
 
 tance from the 100 cc mark to the rim shall be not less than 114 
 
 inches nor more than 134 inches. ‘The graduations shall not be 
 in error by more than 1 cc at any point on the scale. 
 
 PROCEDURE. 
 
 The condenser bath shall be filled with cracked ice* and 
 enough water added to cover the condenser tube. The tempera- 
 ture shall be maintained between 32 and 40° F. (o and 4.5°C.). 
 
 - 8 Any other convenient cooling medium may be used. 
 
8 Circular of the Bureau of Standards. 
 
 The condenser tube shall be swabbed to remove any liquid 
 remaining from the previous test. A piece of soft cloth attached 
 to a cord or copper wire may be used for this purpose. The 
 
 The bulb of the distillation thermometer shall be covered 
 uniformly with a long-fiber absorbent cotton weighing not less 
 than 3 nor more than 5 mg. A fresh portion of clean cotton shall 
 be used for each distillation. 
 
 One hundred cubic centimeters of the tains shall teeta meas- 
 ured in the 100 cc graduated cylinder at 55 to 65° F. (12.8 to 
 18.3° C.) and transferred directly to the Engler flask. None of 
 the liquid shall be permitted to flow into the vapor tube,  _ 
 
 The thermometer provided with a cork shall be fitted tightly 
 into the flask, so that it will be in the middle of the neck and so 
 that the lower end of the capillary tube is on a level with the 
 inside of the bottom of the vapor outlet tube at its iunation with 
 the neck of the flask. 
 
 The charged flask shall be placed in the 1r v, dict Shaeine 
 in the 6 by 6 inch asbestos board, with the vapor outlet tube 
 inserted into the condenser tube. A tight connection may be 
 made by means of a cork through which the vapor tube passes. 
 The position of the flask shall be so adjusted that the vapor tube 
 extends into the condenser tube not less than 1 inek nor more ‘than 
 2 inches. 
 
 The graduated cylinder used in measuring the etlabae shall be 
 placed, without drying, at the outlet of the condenser tube in 
 such a position that the condenser tube shall extend into the 
 graduate at least 1 inch but not below the 100 cc mark. Unless 
 the temperature is between 55 and 65° F. (12.8 and 6 i i C.) the 
 receiving graduate shall be immersed up to the 100 ce mark in a 
 transparent bath maintained between these temperatures. The 
 top of the graduate shall be covered closely during the distillation 
 with a piece of blotting paper or its equivalent cut so as to at tng 
 condenser tube tightly. 
 
 When everything is in readiness, heat shall be applied at a 
 uniform rate, so regulated that the first drop of condensate falls 
 from the condenser in not less than. 5 nor more than 10 minutes. 
 When the first drop falls from the end of the condenser, the 
 reading of the distillation thermometer shall be recorded as the 
 wnitial boiling point. ‘The receiving cylinder shall then be moved 
 so that the end of the condenser tube shall touch the side of the 
 cylinder. The heat shall then be so regulated that the distilla- 
 tion will proceed at a uniform rate of not less than 4 nor more 
 
Specification for Mineral Spirits. 9 
 
 than 5 cc per minute. The reading of the distillation thermometer 
 shall be recorded when the level of the distillate reaches each 
 10 ce matk on the graduate. After the 90 per cent point has 
 been recorded, the heat may be increased because of the presence 
 of the heavy ends which have high boiling points. However, no 
 further increase of heat should be applied after this adjustment. 
 The 4 to 5 cc rate can rarely be maintained from the 90 per cent 
 point to the end of the distillation, but in no case should the 
 period between the 90 per cent and the end point be more than 
 five minutes. 
 
 The heating shall be continued until the mercury reaches a maxi- 
 mum and starts to fall consistently. The highest temperature 
 observed on the distillation thermometer shall be ‘recorded as the 
 maximum temperature or end point. Usually this pomt will be 
 reached after the bottom of the flask has become dry. The 
 total volume of the distillate collected in the receiving graduate 
 shall be recorded as the recovery. ‘The cooled residue shall be 
 poured from the flask into a small cylinder graduated im 0.1 cc, 
 measured when cool and the volume recorded as residue. The 
 difference between 100 cc and the sum of the recovery and the 
 residue shall be calculated and recorded as distillation loss. 
 
 (g) Acipity.—Collect in a test tube the cooled residue from 
 
 the distillation flask (see (f)), add three volumes of distilled water 
 
 and shake the tube thoroughly. Allow the mixture to separate 
 and remove the aqueous layer to a clean test tube by means of a 
 pipette. Add one drop of a 1 per cent solution of methyl orange. 
 No pink or red color should be formed. 
 
 5. BASIS OF PURCHASE. 
 
 (a) Unrr.—Mineral spirits shall be purchased either (1) by 
 volume, the unit being a gallon of 231 cubic inches at 15.5° C. 
 (60° F-.), or (2) by weight. A gallon of mineral spirits at 15.5° C. 
 (60° F.) weighs 6.3 to 6.8 pounds. The exact weight in pounds 
 per gallon of any sample can be determined by multiplying the 
 specific gravity at 15.5/15.5° C. (60/60° F.) by 8.33. HExample— 
 If the specific gravity at 15.5° C. is 0.7642, the weight per gallon 
 at this temperature will be 0.7642 X8.33 = 6.366 pounds. When 
 purchased by weight, quotations shall be by the pound or by 
 the 100 pounds. The request for bids will state whether quota- 
 tions shall be by the gallon, pound, or 100 pounds. 
 
 (b) CORRECTION OF VoLUME.—The gallonage paid for shall be 
 the volume corrected to a standard temperature of 15.5° C. 
 
10 Circular of the Bureau of Standards. 
 
 (60° F.). The correction shall be made by deducting from (when 
 the temperature of gauging is above 15.5° C.) or adding to (when 
 the temperature of gauging is below 15.5° C.) the gallonage as 
 gauged. Such deduction or addition shall be computed on the 
 basis of a coefficient of expansion of 0.000945 per degree centigrade 
 (or 0.000525 per degree Fahrenheit). Example—If the tem- 
 perature at which the spirits is gauged is 75° F., and the 
 volume delivered (at that temperature) is 8,000 gallons, then 
 0.000525 X15 X 8,000 equals the quantity in gallons which must 
 be subtracted from 8,000 gallons to give the true gallonage at 
 60° F., or, if the temperature at which the spirits is gauged is 
 10° C., then 0.000945 X 5.5 X 8,000 equals the quantity in gallons 
 which must be' added to the banged volume of 8,000 —— to 
 give the true gallonage at 15.5° C. 
 
 (c) CERTIFICATION.~—Mineral spirits delivered in barrels, brew 
 or tank cars shall either be accompanied by an official gauger’s 
 certificate showing the net contents of each container and also 
 the temperature of contents at the time of gauging or shall be 
 subject to gauging by the purchaser’s inspector. {n the absence 
 of a statement of the temperature at the time of gauging on the 
 official gauger’s certificate, or in case the barrels show evidence 
 of loss by leakage or other shortage, the delivery shall be subject 
 to reinspection and regauging by the purchaser’s inspector. 
 
 WASHINGTON, January 2, 1923. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 5 CENTS PER COPY 
 
 PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
 COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 
 
 V.-. 
 
 Eee a ee 
 
Sab pe 
 i. Ca! 
 
DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 
 Ss. W. STRATTON, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS 
 No. 102 
 
 [2d edition. Issued September 22, 1922] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 COMPOSITE, VEHICLE FOR THINNING SEMIPASTE 
 PAINTS WHEN THE USE OF STRAIGHT LINSEED OIL 
 IS NOT JUSTIFIED 
 
 FEDERAL SPECIFICATIONS BOARD 
 STANDARD SPECIFICATION NO. 17 
 This specification was officially adopted by the Federal Specifications Board, 
 
 on February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS 
 
 Page 
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 5: Basis of purchase EG Ash Rite ee erro rr err rare 5 
 
 1. GENERAL 
 
 _ This specification covers a composite vehicle which contains 
 in one liquid drying oil, drier, and volatile thinner. Such prep- 
 arations are sometimes called ‘‘ Thinning Mixtures for Paint,” and 
 are also offered under a variety of trade names, such as “Japan 
 Oil,” “‘ Paint Oil,’ ‘Linseed Oil Substitute,” etc. The last name 
 should, however, not be used, for while such materials may have 
 decided merit they are not substitutes for linseed oil. 
 The composite vehicle must meet the following requirements: 
 - APPEARANCE.—Shall be clear and free from suspended matter 
 and sediment. 
 7787°—22 
 
2 Circular of the Bureau of Standards 
 
 CoLor.—No darker than a solution of 6 g of potassium dichro- 
 mate in 100 cc pure sulphuric acid of specific gravity 1.84. 
 
 Opor.—Not offensive, either in bulk or in its’subsequent use in 
 paint mixtures. 
 
 MIXING WITH LINSEED O1L.—When mixed in any proportion 
 with pure raw linseed oil meeting the specifications of B. S. Cir- 
 cular 82, the resulting mixture shall be clear and shall show no 
 separation or precipitation on standing 18 hours: > =; 
 
 DrRYING.—When flowed on glass, the composite vehicle shall 
 set to touch in not more than 4 hours and dry hard in not more 
 than 6 hours. When mixed with an equal volume of pure raw 
 linseed oil, the resulting mixture when flowed<on glass shall set 
 to touch in not more than 6 hours and dry hard in not more, than 
 8 hours. 
 
 TTOUGHNESS.—The film on glass Bie he 4 Pad 6 hours, at 
 105 to 110°C (221 to 230° F) shall be glossy, tough, and elastic. 
 
 NONVOLATILE. MATTER.—Not less than 50 per cent by weight. 
 
 Acip NuMBER.—Not more than 12, calculated ‘to basis of non- 
 volatile matter. — Te 
 
 Nortr.—Deliveries will, in general, be sampled and tested by the following methods, 
 
 but the purchaser reserves the right to use any additional available snlormatog to 
 ascertain whether the material meets the sey aes on 
 
 2. SAMPLIN G 
 
 It is mutually agreed by buyer, and seller that a single package 
 out of each lot of not more than 1000 packages be taken as rep- 
 resentative of the whole. Whenever possible an original. un- 
 opened container shall be sent to the laboratory, and: when for any 
 reason this is not done, the inspector shall thoroughly mix the 
 contents of the containers sampled, transfer not less than 1 quart 
 to a clean, dry, glass bottle! or'tin can, which must be nearly filled 
 with the sample, securely stoppered with a new, clean cork or well- 
 fitting cover or cap, sealed, and distinctly labeled by” the in- 
 spector. The inspector should take a duplicate from the container 
 sampled to hold for check in case of dispute, and when. Tequested 
 should take a sample for the seller. 
 
 Fri LABORATORY EXAMINATION’ Or 
 
 (a) APPEARANCE. Fill two test ‘tubes of, ‘the same, size, eq 
 cm or 6 inches), with the. thoroughly mixed, sample. to ‘within 
 2.5 cm (1 inch) of the top. Stopper the tubes with clean corks. 
 Let stand for 24 hours. Note whether sediment is evident in 
 
Specification for Composite Vehicle 3 
 
 the tubes; if not, shake one tube vigorously and compare the 
 two tubes. If they still look alike and the liquid appears clear, 
 the sample is considered free from sediment and suspended 
 matter. 
 
 (b) CoLor.—Prepare a standard color solution by dissolving 
 6 g of pure powdered potassium. dichromate in 100 cc of pure 
 concentrated sulphuric acid of specific gravity 1.84. Gentle — 
 heat may be used if necessary to perfect the solution of the dichro- 
 mate. ‘The standard color solution and a sample of composite 
 vehicle to be tested shall be placed in clear, thin-walled glass 
 tubes of the same diameter. ‘The color comparison shall be made 
 by placing the tubes close together and looking through them by 
 transmitted light. The tubes used for this test should be 1.5 
 to 2.0 cm (3% to +4 inch) in diameter and shall be filled to a depth 
 of at least 2.5 cm ie inch). 
 
 (Since the potassium dichromate-sulphuric acid must be freshly 
 made for this color comparison, it is frequently more convenient 
 to compare samples with a permanently sealed tube of composite 
 vehicle which has previously been found to be slightly lighter im 
 color than the standard solution of 6 g dichromate in sulphuric 
 acid. When samples are found to be darker than this sealed tube 
 of composite vehicle, the dichromate standard should be made up 
 for final decision.) 
 
 (c) Opor:—Note the odor of the material in bulk, pour a small 
 portion in»a shallow flat-bottomed dish, and allow to stand ex- 
 posed to the air for not less than 48 hours: Flow some on a glass 
 plate and allow to dry in a vertical position for not less than 48 
 hours. Note the odor of these test. portions from time to time. 
 A mild odor of wood turpentine or of fish oil should not be cause 
 for rejection; but a pronounced offensive odor, either due to very 
 crude wood turpentine, rank fish oil, or other offensive substances, 
 would be cause for rejection: 
 
 ((d) Mrxinc-with LINSEED O1L.—Thoroughly mix 25 cc of the. 
 sample with 25 cc pure raw linseed oil and transfer portions of the 
 mixture to two similar test tubes which shall be filled to within 
 2.5 cm (1 inch) of the top and stoppered with clean corks. 
 
 Thoroughly mix 5 cc of the sample with 45 cc of pure raw lin- 
 seed oil and transfer portions of the mixture to two similar test 
 tubes, which shall be filled to within 2.5 em (1 inch) of the top and 
 stoppered with clean corks. 
 
 Let the four tubes stand for 24 hours and note stag any sediment 
 or curdling is apparent in any of the tubes:* If not, shake one tube 
 
4 Circular of the Bureau of Standards 
 
 of each pair vigorously and then compare with the utishaken tube 
 of the same dilution. If the tubes of the same dilution still look 
 alike, the sample is considered to mix properly with linseed oil. 
 
 (e) Dryinc.—Pour the undiluted sample and the mixture with 
 an equal volume of linseed oil on clean glass plates not less than 
 15 cm (6 inches) long and 10 em (4 inches) wide. Place the plates 
 in a nearly vertical position in a well-ventilated) room. but not in 
 the direct rays of the sun. The temperature of the room should 
 be from 21 to 32° C (70 to 90° F). . The films are tested at points 
 not less than 2.5 cm (1 inch) from the edges of the films by touch- 
 ing with the finger. The material is considered to have set to 
 touch when gentle pressure of the finger shows a tacky condition 
 but none of the material adheres to the finger. The material is 
 considered to have dried hard. when the pressure that cam be ex- 
 erted between the thumb and finger does not move the film nor 
 leave a mark that remains noticeable after the spot is sdighitly 
 polished. 
 
 (f) TouGHNEss.—Pour the undiluted sample on.a be x 
 plate. Let drain in a vertical position for 2 minutes, then place 
 in a horizontal position, film up, and let stand at room tempeta- 
 ture for 2 hours. Then bake at a temperature of 105 to 110° C 
 (221 to 230° F) for 6 hours. Remove from the oven and let stand 
 at room temperature for not less than 18 hours. The resulting 
 film shall be glossy and when tested with a knife blade shall show 
 elastic properties, turning up with the blade of the knife in an 
 elastic ribbon without cracking or breaking. ‘The film shall also 
 stand rapid light rubbing without breaking the surface. puke 
 
 (9) NONVOLATILE MaTrEer.—Place a portion of the sample in 
 a stoppered bottle or weighing pipette. . Weigh the container and 
 sample. Transfer about 1.5 g of the sample toa weighed flat- 
 bottomed metal dish about 8 cm in diameter (a friction-top can 
 plug). Weigh the container again and by difference calculate 
 the exact weight of the portion of sample transferred to the 
 weighed dish. Heat the dish and contents in an oven maintained 
 at 105 to 110° C (221 to 230° F) for 3 hours. Cool and weigh. 
 From the weight of the residue left in the dish and weight of the 
 sample taken calculate the percentage of nonvolatile matter. 
 
 (1) Actb NuMBER.—Place a portion of the sample in a stop- 
 pered bottle or weighing pipette. Weigh the container and 
 sample. Transfer an amount corresponding to between 1 and 2 g 
 of nonvolatile matter (see (g)) to a 200 ce Erlenmeyer flask, 
 reweigh the container and calculate the exact weight taken, add 
 
Specification for Composite Vehrcle 5 
 
 25 cc of neutral pure benzol and 25 cc of neutral ethyl alcohol, or 
 ethyl alcohol denatured with pure benzol or pure methyl alcohol. 
 (The alcohol used in all cases must be neutral.)« Boil for 30 
 minutes. (It is best to use a reflux condenser.) Cool to room 
 temperature, add 4 drops of phenolphthalein indicator solution, 
 and titrate with standard alcoholic sodium hydroxide. From 
 the number of cubic centimeters of standard hydroxide solution 
 calculate the acid number to the basis of the nonvolatile resi- 
 due. (Acid number is milligrams of KOH required to neutralize 
 acid in 1 g of material tested.) 
 
 4. REAGENT 
 
 ALCOHOLIC SODIUM HypROXIDE SOLUTION.—Dissolve pure so- 
 dium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 ‘about 22 g per 1oooce. Let stand ina stoppered bottle. Decant 
 the: clear liquid into another bottle and keep well stoppered. 
 Standardize against half normal sulphuric or hydrochloric acid, 
 using phenolphthalein as indicator. This standardization must 
 be made each day that the solution is used. 
 
 This solution should be colorless or only slightly yellow when 
 used, and it will keep colorless longer if the alcohol is previously 
 treated with sodium hydroxide (about 80 g to 1000 cc) kept at 
 about 50° C for 15 days and then distilled. 
 
 5. BASIS OF PURCHASE 
 
 Composite vehicle shall be purchased by volume, the unit being 
 a gallon of 231 cubic inches at 15.5° C (60° F). The volume may 
 be determined by measure or, in case of large deliveries, it may 
 be easier to determine the net weight and specific gravity at 
 15.5/15-5° C (60/60° F) of the delivery. The weight per gallon in 
 pounds can then be determined by multiplying the specific grav- 
 ity by 8.33. The net weight in pounds divided by the weight 
 per gallon gives the number of gallons. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 5 CENTS PER COPY 
 V 
 
 WASHINGTON : GOVERNMENT PRINTING OFFICB : 1922 
 
4 
 
U. S. Gov't 
 Master 
 Specification 
 
 No. 18b 
 
 DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 103 
 
 [4th ed., issued October 5, 1926] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 VARNISH, SPAR, WATER-RESISTING 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 18b 
 [Revised August 7, 1926] 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on February 3, 1922, for the use of the departments and independent 
 establishments of the Government in the purchase of water-resisting spar 
 varnish. ’ 
 
 [The latest date on which the technical requirements of this revision shall become mandatory for all 
 
 departments and independent establishments of the Government is November 7, 1926. They may be 
 put into effect, however, at any earlier date; after promulgation.] 
 
 CONTENTS 
 
 A) 
 ) 
 3 
 
 III. Material and workmanship. ---------------------------------- 
 IV. General requirements ---------------------------------------- 
 V. Detail requirements----------------------------------------- 
 VI. Methods of sampling, testing, and basis of purchase------------- 
 1. Sampling. -...-.------------------------------------- 
 
 2. Laboratory examination_-_-_._-------------------------- 
 
 3. Basis of purchase_------------------------------------ 
 
 Wit, Packing ..........-------.--.---+-------------+--+------+-- 
 WHIT. Notes... <.-2------ 2 ee ee ong sen 5 5 ee 8 
 
 I. GENERAL SPECIFICATIONS 
 
 DaOoOwns NNW WN KF 
 
 There are no general specifications applicable to this specification. 
 Il. GRADE 
 
 Water-resisting spar varnish for general use shall be of one grade 
 only, as hereinafter described. 
 10414°—26t 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 Ill. MATERIAL AND WORKMANSHIP 
 
 The manufacturer is given wide latitude in the selection of raw 
 materials and processes of manufacture so that he may produce 
 varnish of the highest quality. 
 
 IV. GENERAL. REQUIREMENTS 
 There are no general requirements applicable to this specification. 
 V. DETAIL REQUIREMENTS | 
 
 1. AppEARANCE.—Clear and transparent. 
 
 2. Conor.—Not darker than a solution of 3 g of potassium dichro- 
 mate in 100 cc._of puresulphuric acid, specific — 1.84. 
 
 . Fuasu Pornt (Ciosep-Curp).—Not below 30° C. (85° F.). 
 
 . Nonvouatite Marter.—Not less than 45 a cant by Mesias 
 
 . Ser ro Toticx.—In not more than five hours.:' | 
 
 . Dry Harp anv Tovucu.—In not more than 24 hours. 
 
 . Viscosiry.—Not less than 1.40 nor more than 2.25 poises. _ 
 
 . Worxine Propertius.—Varnish shall have good. brushing, 
 flowing, covering, and. leveling properties... The dried film shall 
 ‘have the characteristic gloss of spar varnish. rinieey: 
 
 9. Saretry of Worxinc.—Shall pass the draft test. 
 
 10. Water ReststAncze.—Dried film shall withstand gold water 
 for 18 hours and boiling water for 15 minutes without whitening 
 or dulling. 
 
 11. ToucHuness.—Shall pass a 50>per cent kauri reduction test 
 af 24° Oo(T 5 a), 
 
 ee SS ee 
 
 VI. METHODS OF SAMPLING, TESTING, AND BASIS ee 
 PURCHASE : | 
 
 tj - 
 
 Deliveries will, in general, be sampled and tested by the one 
 methods, but the purchaser reserves the right to use any additional infor- 
 mation to ascertain whether the material meets the specification. 
 
 1. SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not. more than 1,000, packages will be taken as 
 representative of the whole. Whenever possible an original unopened 
 container shall be sent to the laboratory, and when for any reason 
 this is not done the inspector shall thoroughly mix the contents 
 of the container sampled, transfer not less than 1 quart to a clean 
 dry glass bottle or tin can, which must be nearly filled with the 
 ight Fy securely stoppered with a new clean cork or well-fitting 
 cover or cap, sealed, and distinctly labeled by the inspector. The 
 
SPECIFICATION FOR SPAR VARNISH 3 
 
 inspector should take a duplicatefrom the container sampled to be held 
 for check in case of dispute, and, when requested, should take a 
 sample for the seller. 
 
 Zz. LABORATORY EXAMINATION 
 
 The tin panels used in the following tests shall all be cut from 
 bright tin plate weighing not more than 25 g nor less than 19 ¢g 
 per square decimeter (0.51 to 0.39 pound per square foot). (Com- 
 mercial No. 31 gauge bright tin plate should weigh about 0.44 
 pound per square foot. It is important that the tin plate used shall 
 be within the limits set.) The panels shall be about 7.5 by 13 cm 
 (8 by 5 inches) and must be thoroughly cleaned with benzol imme- 
 diately before using. 
 
 (2) AppraARANCcE.—Pour some of the thoroughly mixed sample 
 into a clear glass bottle or test tube and examine by transmitted 
 light. The varnish must be clear and transparent. 
 
 (b) Cotor.—Prepare a standard color solution by dissolving 3 g 
 of pure powdered potassium dichromate in 100 cc of pure concen- 
 trated sulphuric acid of specific gravity 1.84. Gentle heat may be 
 used if necessary to perfect the solution of the dichromate. The 
 standard color solution and a sample of the varnish to be tested 
 shall be placed in clear thin-walled glass tubes of the same diameter. 
 The color comparison shall be made by placing the tubes close. to- 
 gether and looking through them by transmitted light. The tubes 
 used for this test should be 1.5 to 2.0 cm (5% to +4 inch) in diameter 
 and shall be filled to a depth of at least 2.5 em (1 inch). (Since the 
 potassium dichromate-sulphuric acid must be freshly made for this 
 color comparison, it is frequently more convenient to compare sam- 
 ples with a permanently sealed tube of varnish which has previously 
 been found to be slightly lighter in color than the standard solution 
 of 3 g dichromate in sulphuric acid. When samples are found to be 
 darker than this standard tube of varnish, the dichromate standard 
 should be made up for final decision.) 
 
 (c) Fuasa Point.—Determine with either the Tag or Elliott closed- 
 cup tester. The former is preferred.’ 
 
 (d) NonvouatTiteE Matrrer.—Place a portion of the sample in a 
 stoppered bottle or weighing pipette. Weigh container and sample. 
 Transfer about 1.5 g of the sample to a weighed flat-bottomed metal 
 dish about 8 cm in diameter (a friction-top can plug). Weigh con- 
 tainer again and by difference calculate the exact weight of the por- 
 tion of sample transferred to the weighed dish. Heat dish and 
 contents in an oven maintained at 105 to 110° C. (221 to 230° F.) 
 for three hours. Cool and weigh. From the weight of the residue 
 
 1 Directions for using the Tag tester may be found in A. S. T. M. Standards D 56-21, and directions 
 for using the Elliott cup in Proceedings A. S. T. M., 1917, part 1, p. 414. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 left in the dish and weight of the sample taken calculate the per- 
 centage of nonvolatile residue. 
 
 (e) Sertine To Toucn AND Dryine Timu.—Pour the varnish on 
 one of the tin panels described above. Place the panel in a nearly 
 vertical position in a well-ventilated room but not in the direct 
 rays of the sun. The atmosphere of this room must be free from 
 products of combustion or laboratory fumes. The temperature of 
 the room should be from 21 to 32° C. (70 to 90° F.). The film is 
 tested at points not less than 2.5 cm (1 inch) from the edges of the 
 film by touching lightly with the finger. The varnish is considered 
 to have set to touch when gentle pressure of the finger shows a tacky 
 condition but none of the varnish adheres to the finger. The var- 
 nish is considered to have dried hard when the pressure that can be 
 exerted between the thumb and finger does not move the film or 
 leave a mark which remains noticeable after the spot is lightly 
 polished. If rapid light rubbing breaks the surface, the sample is 
 considered not to have satisfactorily dried hard. In case the test 
 shows time of setting to touch or drying hard more than 5 and 24 
 hours, respectively, two additional tests shall be run on different 
 days, and if the varnish does not meet the above drying and harden- 
 ing requirements on both of these additional tests it shall be con- 
 sidered unsatisfactory. In cases where different laboratories fail to 
 agree on the drying test, due to different atmospheric conditions, 
 and umpire tests are necessary, such tests shall be made in a well- 
 ventilated room maintained at a temperature of 70° F. and relative 
 humidity of 65 per cent saturation. — ne 
 
 (f) Viscosrry.—Determine the viscosity of the varnish by compari- 
 son at 25° C. (77° F.) with secondary standards whose viscosity ex- 
 pressed in poises has been accurately determined at that temperature.’ 
 - (g) Worxine Proprrtizs.—Coat a smooth clean panel of metal 
 or wood with the sample, using a good varnish brush. Observe 
 whether the varnish shows objectionable “pulling” under the brush 
 and whether the varnish film levels and yields a surface of good — 
 appearance. Br 
 f(h) Savery or Worxine.—Draft test—Flow the varnish on one 
 of the standard tin panels and immediately place the panel in the — 
 direct draft of a small (8 or 10 inch) electric fan running at full 
 } speed. The panel should be placed approximately 2 feet from the 
 fan in a nearly vertical position and at an angle of 45° to the line of 
 the air current. Allow the panel to remain in this position for five 
 hours, remove, and allow to harden overnight. The-varnish shall 
 show no dulling, crow’s footing, or frosting, This. test shall be 
 
 et 
 
 ardner-Holdt tubes may be used, in which case the limits are tube “F’” to ok Paid inclusive. * See Ph 
 Circular No. 178, Srientific Section, Paint Manufacturers’ Association of the United States. eaelin tig 
 
 . Lt ate: 2) scnlgeitig. rire, 
 
 5 anit yectaagae ot 
 
a 
 
 SPECIFICATION FOR SPAR VARNISH 5 
 
 made under the same room and temperature conditions noted under 
 ‘Setting to touch and drying time,” Section VI, 2, (€). suns" 
 _. (i) Warr Resistance.—Pour the varnish Sn two of the tin 
 
 “panels described above and allow to dry under the conditions de- 
 
 scribed in paragraph (e) for 48 hours. Place one of these panels 
 in a beaker containing about 2.5 inches of distilled water at room 
 
 temperature (immersing the end of the panel which was upper- 
 
 most during the drying period) and leave in water for 18 hours. 
 The varnish shall show no whitening and no more than very slight 
 dulling either when observed immediately after removing from 
 the water or after drying for two hours. Place the other panel 
 
 in a beaker containing about 2.5 inches of boiling distilled water 
 
 (immersing the end of the pane! which was uppermost during the 
 drying period) and allow to remain in the boiling water for 15 
 
 ‘minutes. The varnish shall show no whitening and no more than a 
 
 very slight dulling either when observed immediately after removing 
 from the water or after drying for two hours. 
 
 (j) Touauness.—The toughness of the varnish is determined by 
 the Kauri reduction test, as follows: By proportionately reducing its 
 toughness by the addition of s standard solution of “run-Kauri” 
 gum in pure spirits of turpentine. 
 
 (1) Preparation of the “run Kauri.”—Arrange a distillation flask, 
 water-cooled condenser, and a tared receiver on a balance. Place 
 in the flask about one-third of its volumetric capacity of clear, 
 bright hard pieces of Kauri gum broken to pea size. Carefully melt 
 and distill until 25 per cent by weight of the gum taken is collected 
 in the tared receiver. Pour the residue into a clean pan and when 
 cold break up into small pieces. | 
 
 (2) Preparation of standard “run Kauri” solution—Place a 
 quantity of the small broken pieces of run Kauri, together with 
 twice its weight of freshly redistilled spirits of turpentine, using only 
 
 - that portion distilling over between 153 and 170° C. (308 and 338° F.) 
 in a carefully tared beaker. Dissolve by heating to a temperature 
 ‘of about 149° C. (300° F.) and bring back to correct weight when 
 cold by the addition of the amount of redistilled spirits of turpentine 
 
 necessary to replace the loss by evaporation during the dissolving of 
 the gum. 
 
 (3) Reduction of the varnish.—Having carefully determined the 
 nonvolatile content of the varnish according to the method under 
 paragraph (d) of this specification, take 100 g of the varnish and 
 add to it an amount of the standard run-Kauri solution equivalent to 
 50 per cent, by weight, of the nonvolatile matter in the varnish. 
 Mix the varnish and the solution thoroughly. 
 
 (4) Application of the varnish—Flow a coat of the varnish thus 
 reduced on one of the tin panels described above and let stand in a 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 nearly vertical position at room temperature for one hour. Next 
 place the panel in a horizontal position in a properly ventilated oven 
 and bake for five hours at 95 to 100° C. Remove the panel from the 
 oven and allow to cool at room temperature, preferably 24° C. 
 (75° F.) for one-half hour. 
 
 (5) Bending the panel.—Place the panel with the varnished side 
 uppermost over a 3 mm (-inch) rod, held firmly by suitable sup- 
 ports, at a point equally distant from the top and bottom edges of the 
 panel and bend the panel double rapidly. The varnish must show 
 no cracking whatsoever at the point of bending. For accurate results 
 the bending of the panel should always be done at 24° C. (75° F.), 
 for a lowering of the temperature will lower the percentage of reduc- 
 tion that the varnish will stand without cracking, while an increase 
 in the temperature increases the percentage of reduction peer the 
 varnish will stand. 
 
 3. BASIS OF PURCHASE > 
 
 Varnish shall be Regohenel by volume, the unit edad a allen of 
 231 cubic inches at 15.5° C. (60° F.). The volume may be deter- 
 mined by measure, or, in case of large deliveries, it may be easier to 
 determine the net weight and specific gravity at 15.5/15.5° C. 
 (60/60° F.) of the delivery... The weight per gallon in pounds can 
 then be determined by multiplying the specific gravity by 8.33. 
 The net weight in pounds divided by the weight per enrer gives the 
 number of gallons. 
 
 vit. PACKING 
 
 Packing shall be in accordance with commercial practice unless 
 otherwise specified. | | 
 
 VIII. NOTES 
 
 _ Water-resisting spar varnish is intended to meet all the needs of 
 the Government for a general utility varnish, suitable for both out- 
 side and inside exposure, where durability is the chief requisite and 
 where high gloss or initial hardness of the film are not required. 
 It does not, however, fulfill all the requirements for an aircraft varnish. 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 esi ae D. C. 
 
 & CENTS PER COPY 
 Vv 
 
F. 
 
 “se 
 
 a3 
 
ae 
 
 Pe Gecaran? 8 
 
 Page 
 v5 a : 
 
DEPARTMENT OF COMMERCE. 
 
 BUREAU OF STANDARDS. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 No. 104. 
 
 [2d Edition. Issued January 30, 1923.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 ASPHALT VARNISH. 
 
 Gene 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION No. 19. 
 
 [Revised January 2, 1923.] 
 
 This specification was officially adopted by the Federal Specifications Board 
 on February 3, 1922, for the use of the departments and independent establish- 
 ments of the Government in the purchase of asphalt varnish. 
 
 CONTENTS. 
 Page 
 IN ee i eh ig welatne He da CNR E Phe Gen bn Ces es 9 ee I 
 rane laa to) a2. Ns Sa eas EO RRA BE, a. . ie OT EAS Be 2 
 3. Laboratory examination..............-.s eee cece ete nett eee n eee ee tenes 3 
 4; Basis of purchases; 0). 05 5G. i eb ee ee ae RETR ee peewee tle ns 7 
 1. GENERAL. 
 
 This varnish shall be composed of a high grade of asphalt 
 fluxed and blended with properly treated drying oil and thinned 
 to the proper consistency with a volatile solvent. It must be 
 resistant to air, light, lubricating oil, water, and, when the con- 
 tract so specifies, to mineral acids of the concentration herein- 
 after specified. It must meet the following requirements: 
 
 APPEARANCE.—Smooth and homogeneous; no livering or 
 stringiness. 
 
 CoLor.—Jet black. 
 
 FLsasH Pornt (CLosED-Cup).—Not below 30° C. (86° F.). 
 
 27817°—23 
 
2 Circular of the Bureau of Standards. 
 
 ACTION WITH LINSEED O1L.—Varnish must mix readily to a 
 homogeneous mixture with an equal volume of raw linseed oil. 
 
 MATTER INSOLUBLE IN CARBON BISULPHIDE.—Not more than 
 I per cent. 
 
 NONVOLATILE MATTER. i less than 40 per Sent by weight. 
 
 Fatry MaTrer.—Not less than 20 per cent of the nonvolatile. 
 Must be liquid and not show a violet coloration by the Liebermann- 
 Storch test. : | 
 
 Set To ToucH.—Within 5 hours. 
 
 Dry Harp AnD JouGcH.—Within 24 hours. 
 
 TouUGHNESS.—Film.on metal. must withstand rapid bending 
 over a rod 3 mm (% inch) in diameter. 
 
 WorkiNG PRropERTIES.—Varnish must heve good brushing, 
 flowing, covering, and leveling properties. 
 
 RESISTANCE TO WATER.—Dried film must withstand cold water 
 for 18 hours. : 
 
 RESISTANCE ‘TO Or.—Dried film’ must ‘withstand lubricating 
 oil for 6 hours. 
 
 RESISTANCE TO MINERAL AcIDs. '_Dried film must withstand 
 action of the following acids for six hours: Sulphuric acid, specific 
 gravity 1.25 (about 33 per cent), Nittie acid, specific’ ‘gravity 
 1.12 (about 20 per cent). Hydrochloric acid; specific gravity 
 1.09 (about 18 per cent). i , a 
 
 NotE.—Deliveries will, in general, be sampled and tested by the following methods, 
 
 but the purchaser reserves the right to use any additional available information to 
 ascertain whether the material meets the specification. 
 
 2. SAMPLING. 
 
 7 
 soe ie Pe h 
 
 It is mutually agreed by buyer and seller that a press pealialics 
 out of each lot of not more than 1,000 packages be taken as repre- 
 sentative of the whole. Wherever possible, an original unopened 
 container shall be sent to the laboratory. When for any reason this 
 can not be done, the inspector shall select a package and thoroughly 
 mix its contents... He shall fill a 1 quart, clean, dry. container from 
 this package, securely stopper it witha new. clean: cork or, well- 
 fitting cover.or. cap, seal, and distinctly ; label it, The. inspector 
 shall take a duplicate from,the container sampled to, be. held for 
 check in case of dispute, and, when requested, shall take a eels 
 for the seller. 
 
 1 Only required when the contract specifically demands asphalt varnish that is resistant to mineral acids. 
 
Specification for Asphalt Varnish. 3 
 3. LABORATORY EXAMINATION. 
 
 (a) APPEARANCE AND CoLor.—Pour some of the thoroughly 
 mixed sample on a clean, clear glass plate and stand in a vertical 
 position until the excess varnish has drained off. Examine the 
 film by transmitted light. The-varnish must be smooth and 
 homogeneous and must not show any separation or segregation 
 of the constituents. Examine the film by reflected light. The 
 _ film must be jet black in color. 
 
 (6) Fiass Point,—Determine with either the ‘Tag’ or 
 Elliott closed-cup tester. The former is preferred.’ 
 
 (c) ACTION wiTtH LINSEED O1L.—Pour 10 cc of the varnish 
 into a test tube and add an equal volume of raw linseed oil con- 
 forming to Bureau of Standards Circular No. 82. Stopper the 
 test tube and shake vigorously for several minutes. Then pour 
 some of the mixture on a clear glass plate and stand in a vertical 
 position. After the excess varnish has drained off examine the 
 film by transmitted light. There shall be no separation of the 
 oil and varnish. 
 
 __ (d) Matrer INSOLUBLE IN CARBON one e —Weigh about 
 
 5 g of the varnish into a small beaker, add 25 cc of carbon bisul- 
 ae and allow to stand for 15 minutes. Filter through a 
 weighed Gooch crucible, prepared with a medium thick mat of 
 asbestos, using suction if necessary to aid in filtration. Wash 
 the residue in the crucible with carbon bisulphide until the wash- 
 ings are colorless. Dry in air at room temperature until the odor 
 of carbon bisulphide has almost disappeared, and then for one 
 _ hour in an oven at 110°C. Cool and weigh. From the weight of 
 the insoluble left in the crucible and the weight of sample taken 
 calculate the percentage of insoluble in carbon bisulphide. 
 
 (ec) NONVOLATILE MaTTEeR.—Place a portion of the sample in a 
 stoppered bottle or weighing pipette. Weigh the container and 
 sample. Transfer about 1.5 g of the sample to a weighed flat- 
 bottomed metal dish about 8 cm in diameter (a friction-top can 
 plug). Weigh the container again and by difference calculate the 
 exact weight of the portion of sample transferred to the weighed 
 dish. Heat the dish with its contents in an oven maintained at 
 -to5 to 110° C. for three hours. Cool and weigh. From the 
 weight of the residue left in the dish and the weight of the sample 
 taken calculate the percentage of nonvolatile residue. 
 
 2 Directions for using the “’Tag’”’ tester may be found in A. S. T. M. Standards Ds56-21, and directions 
 for using the Elliott cup in Proceedings A. S. T. M., 1917, pt. 1, D. 414. 
 
 f 
 
 “ 
 
 t* 
 
4 Circular of the Bureau of Standards. 
 
 (f) Fatry Matrer.—Weigh about 5 g of the varnish into a 
 wide-mouthed flask, add 50 ce of benzol and 5 g of clean, fine 
 silica sand and heat under a reflux condenser on a steam bath 
 until the varnish is entirely dissolved. Add 25 cc of ethyl alcohol 
 denatured with methyl alcohol and 25 cc of a 0.5 N alcoholic 
 caustic soda solution and continue boiling under the reflux con- 
 denser for one-half hour. Remove the condenser and evaporate 
 the solution to dryness. Add to the residue in the flask 50 cc of 
 distilled water and heat until the residue is disintegrated. Filter 
 the water solution of the soaps. Repeat this operation with 25 
 cc portions of water until the residue is completely disintegrated 
 and the wash water is clear and colorless. 
 
 Combine the filtrates (the soap solution and washings), deidity 
 with hydrochloric acid, and heat until the fatty acids and any 
 emulsified asphalt separate and rise to the top and the water 
 below is clear. Cool, transfer to a separatory funnel, and extract 
 three times with 25 cc portions of ether. Combine the ether ex- 
 tracts and wash with water until free from acid. Filter the ether 
 extracts through paper into a beaker and wash the residue on the 
 paper with ether until the washings run through colorless. Evap- 
 orate the ether solutions to dryness. 
 
 Add ro to 15 ce of 95 per cent ethyl alcohol to the residue in 
 the beaker and warm on the steam bath. Cool to room tempera- 
 ture and filter through paper into a tared flask or dish. Repeat 
 this operation with 5 cc portions of 95 per cent ethyl alcohol 
 until the alcohol remains colorless. Finally wash the residue on 
 the paper with 95 per cent ethyl alcohol until the washings run 
 through colorless. Evaporate the alcoholic solution to dryness on 
 a steam bath and heat for an hour in an oven at 105° C. (221° F.). 
 Cool and weigh. From the weight of the residue in the flask and 
 the weight of the original sample calculate the percentage of fatty 
 matter. ‘ei 
 
 (Sometimes the residue obtained after saponification and the 
 evaporation of the benzol and alcohol from the saponifying mix- 
 ture is not completely disintegrated by boiling with water. In 
 that case extract with water until nothing further dissolves and 
 then dry. Dissolve in benzol, using heat if necessary, and wash 
 the benzol solution several times with water. Heat the washings 
 until the odor of benzol has disappeared and add to the be 2 
 solution before acidifying.) 
 
 The fatty matter obtained above must be a clear amber aioe 
 liquid. A fugitive violet color shall not be obtained when the 
 
_ Specification for Asphalt Varnish. 5 
 
 fatty matter is subjected to the following test: Dissolve a small 
 amount of the fatty matter in 5 cc of acetic anhydride, warming 
 if necessary to aid solution. Cool, draw off the acetic anhydride 
 solution, and add a drop of sulphuric acid, 1.53 specific gravity. 
 
 -(g) Dryinc Trme.—Pour the varnish on a clean glass plate 
 not less than 15 em (6 inches) long and 10 cm (4 inches) wide. 
 Place the plate in a nearly vertical position in a well-ventilated 
 room, but not in the direct rays of the sun. The temperature of 
 the room should be from 21 to 32° C. (7o to 90° F.). Test the 
 film at points at not less than 2.5 cm (1 inch) from the edges of the 
 film by touching lightly with the finger. The varnish is considered 
 to have set to touch when gentle pressure of the finger shows a 
 tacky condition, but none of the varnish adheres to the finger, 
 The varnish is considered to have dried hard when the pressure 
 that can be exerted between the thumb and finger does not move 
 the film or leave a mark which remains noticeable after the spot 
 is lightly polished. If rapid light rubbing breaks the surface, the 
 sample is not considered to have satisfactorily dried hard. In 
 case the test shows time of setting to touch or drying hard more 
 than 5 and 24 hours, respectively, two additional tests shall be 
 run on different days, and if the varnish does not meet the above 
 drying and hardening requirements on both of these additional 
 tests it shall be considered unsatisfactory. In cases where dif- 
 ferent laboratories fail to agree on the drying test, due to different 
 atmospheric conditions, and umpire tests are necessary, such tests 
 shall be made in a well-ventilated room maintained at a tempera- 
 ture of 70° F. and relative humidity of 65 per cent saturation. 
 
 (h) Toucuness.—Flow the varnish on one side of a dry steel 
 plate that has previously been cleaned of all scale, rust, and grease. 
 This plate should be about 0.4 mm (0.016 inch) thick, and 10 by 
 15 cm (4 by 6 inches) will be found of convenient size. Let the 
 test piece dry in a vertical position, not in the direct rays of the 
 sun, in a well-ventilated room at a temperature not below 21° C. 
 (70° F.) for a period of not less than six days. _Now bring the 
 test piece to a temperature between 21 and 24° C. (70 to 75° F.) 
 and, with the varnish film on the outside, bend rapidly over a rod 
 3 mim (% inch) in diameter. The film must show no evidence of 
 cracking or flaking. 
 
 (t) WORKING PROPERTIES.—A clean piece of steel plate similar 
 to that used for testing the toughness of the varnish shall be used 
 for determining the working properties. The plate shall be 
 thoroughly cleaned of all grease and rust and dried. It shall 
 
> ) 
 - oF 
 ne, | 
 
 6 Circular of the Bureau of Standards. 
 
 then be laid in a horizontal position and one coat of the varnish 
 applied by brushing. The varnish shall work easily under the 
 brush, showing no tendency to draw or pull, and shall flow out 
 to a smooth, glossy, jet-black film, free from brush marks, blisters, 
 pinholes, or other defects. Test pieces prepared in the above 
 manner and allowed to dry in a horizontal position, not in the 
 direct rays of the sun, in a well-ventilated room, at a temperature 
 not below 21° C. (70° F.) for a period of not less than six days; 
 shall be used for testing the resistance of the varnish to cold water 
 and lubricating oil. 
 (j) RESISTANCE TO WaTER.—A test piece, prepared and dried 
 as under (i), shall be inclined at an angle of 45° to the vertical, 
 and a gentle stream of cold tap water with a temperature of 
 about 25° C. (77° F.) allowed to flow for 18 hours down the middle 
 of the varnished surface. After wiping off with a soft cloth or 
 chamois skin any deposit due to the tap water the varnish must 
 show no whitening, dulling, softening, or other visible defects. 
 (k) RESISTANCE TO LUBRICATING O1L.—A test piece prepared 
 and dried as under (i) shall be laid flat, and in at least two different 
 places several drops of locomotive engine lubricating oil * allowed 
 to stand in contact with the film for six hours. During the test 
 the spots of oil shall be covered with small watch glasses. After 
 wiping off the oil with cotton waste no softening or other deteri- 
 oration of the film due to the lubricating oil “shall be perceptible. 
 
 (1) RESISTANCE TO MINERAL Acitp.—A piece of dry, steel plate 3 
 
 free from scale, rust, and grease shall be used for this test. It 
 shall be laid in a horizontal position and one coat of the varnish 
 applied by brushing. This coat of varnish shall then be allowed 
 to dry for 24 to 48 hours, when a second coat shall be applied. 
 The second coat shall be allowed to dry, as in (2), for a period of 
 not less than six days before testing. The test pieces shall then 
 be laid flat and in different places several drops each of sulphuric 
 acid, specific gravity 1.25, nitric acid, specific gravity 1.12, and 
 hydrochloric acid, specific gravity 1.09, shall be allowed to remain 
 on the surface of the film for six hours at room temperature, 
 about 21° C. (7o° F.). During the test the drops of acid shall be 
 
 covered with small watch glasses to prevent evaporation. After 
 
 six hours the acid shall be washed off with tap water, and after 
 drying for one hour the spots previously in contact with the acid 
 examined. They shall show no appreciable change in hardness. 
 
 8 A straight mineral oil having a viscosity (Saybolt Universal) of about a sec. at 210° F. ; 
 
bs 
 a 
 BS 
 
 Specification jor Asphalt Varnish. 7 
 
 The film shall then be allowed to dry for 12 hours, when it shall 
 again be examined. ‘The spots exposed to the acid shall show 
 no disintegration or browning, and their luster shall not be im- 
 paired. A slight bloom around the area of the spot exposed to 
 the acid shall not be considered an indication of failure. The 
 film shall then be removed with carbon tetrachloride, chloroform, 
 or carbon bisulphide and the metal examined. It shall show no 
 corrosion. 
 4. BASIS OF PURCHASE. 
 
 Asphalt varnish shall be purchased by volume, the unit being 
 a gallon of 231 cubic inches at 15.5°C. (60° F.). The volume may 
 be determined by measure or, in case of large deliveries, it may be 
 easier to determine the net weight and specific gravity at 15.5/15.5° 
 C. (60/60° F.) of the delivery. The weight per gallon in pounds 
 can then be determined by multiplving the specific gravity by 
 8.33. The net weight in pounds divided by the weight per gallon 
 gives the number of gallons. 
 
 WASHINGTON, January 2, 1923. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 5 CENTS PER COPY 
 
 PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
 COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 
 
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DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 S. W. STRATTON, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 No. 105. 
 
 [2d edition. September 18, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 LIQUID PAINT DRIER. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION No. 20 
 
 This specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the departments and independent establishments of 
 the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 Page. 
 TORTIE TAL: oo... TN CANARD AIA PIAA. ARN, FbTt EE D I 
 RIN eds Sota. SSS a ee ERROR «wid he's WRG TY aN ee Ee 2 
 ai areioryextiavinntion. 42.00/57. . Cee ie ee 2 
 eam Ol HICCHISe 0.) «nas actrees -arld - te pogidis - Ped: UEP Acie aa 4 
 1. GENERAL. 
 
 This specification applies both to straight oil drier—that 1s, 
 material free from resins or ‘‘gums’’—and to Japan drier; that is, 
 material containing varnish ‘‘gums.”’ 
 
 The drier shall be composed of lead, manganese, or cobalt, or 
 a mixture of any of these elements combined with a suitable fatty 
 oil, with or without resins or ‘‘gums,’’ and mineral spirits or tur- . 
 pentine, or a mixture of these solvents. It shall be free from 
 sediment and suspended matter. The drier when flowed on metal 
 and baked for 2 hours at 100° C. (212° F.) shall leave an elastic 
 film. ‘The flash point shall be not lower than 30° C. (85° F.) when 
 tested in a closed-cup tester. It shall mix with pure raw linseed 
 
 7789°—22 
 
2 C ircular of the Bureau of Standards 
 
 oil in the proportion of 1 volume of drier to 19 volumes of oil with- 
 out curdling, and the resulting mixture when flowed on glass shall 
 dry in not more than 18 hours. When mixed with pure raw lin- . 
 seed oil in the proportion of 1 volume of drier to 8 volumes of oil, 
 the resulting mixture shall be no darker than a solution of 6 g of 
 potassium dichromate in 100 ce of pure sulphuric acid of specific 
 gravity 1.84. ) 
 
 Notr.—Deliveries will, in general, be sampled and tested by the following meth- 
 
 ods, but the purchaser reserves the right to use any additional available information 
 to ascertain whether the material meets the specification. 
 
 2. SAMPLING, 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages be taken as repre- 
 sentative of the whole. Whenever possible, an original unopened 
 container shall be sent to the laboratory, and when for any reason 
 this is not done, the inspector shall thoroughly mix the contents 
 of the container sampled, transfer not less than 1 quart to a clean, 
 dry glass bottle or tin can which must be nearly filled with the 
 
 sample, securely stoppered with a new clean cork or well-fitting 
 
 cover or cap, sealed, and distinctly labeled by the inspector. The 
 inspector should take a duplicate from the container sampled to be 
 held for check in case of dispute, and, when requested, should take 
 a sample for the seller. 
 
 3. LABORATORY EXAMINATION. 
 
 (a) SEDIMENT AND SUSPENDED MATTEerR.—Thoroughly mix the 
 sample. Full two test tubes of the same size (15 cm, or 6 inches) 
 to within 2.5 cm (1 inch) of the top with the sample. Stopper 
 the tubes with clean corks. Let stand for 24 hours. Note 
 whether sediment is evident in the tubes; if not, shake one tube 
 vigorously and compare the two tubes. If they still look alike, 
 the sample is considered free from sediment and suspended matter. 
 
 (6) CoLoR.—Mix 2 ce drier and 16 cc clear pure raw linseed oil 
 that complies with the specifications of B. S. Circular No. 82. Dis- 
 solve 6 g of pure powdered potassium dichromate in roo ce of pure 
 concentrated sulphuric acid (specific gravity 1.84). Gentle heat 
 may be used if necessary to secure a perfect solution of the di- 
 chromate. ‘This solution should be freshly prepared. ‘The color 
 comparison shall be made by placing the 1:8 drier-linseed oil mix- 
 ture and the dichromate-sulphuric acid solution in thin-walled 
 glass tubes of the same diameter, 1.5 to 2 cm (5% to 43% inch) to 
 
U. S. Government Specifications for Laquid Pawnt Drier. 3 
 
 depths of at least 2.5 em (1 inch) and comparing the depth of 
 color by looking through the tubes across the column of liquid by 
 transmitted light. . 
 
 (c) MixiInc witH LInsEED OIL, SETTING ‘To Toucu, AND 
 Dryinc.—Mix 1 ce of the sample and 1g cc of clear pure raw 
 linseed oil that complies with the specifications of B. S. Circular 
 No. 82. Thoroughly clean a glass plate, finally washing with 
 benzol and drying. Pour a portion of the mixture of linseed oil 
 and drier over this plate and place the plate in a vertical position 
 in a well-ventilated room, the atmosphere of which is free from 
 products of combustion or laboratory fumes. Allow the remainder 
 of the mixture to stand for 2 hours. No sediment or precipitate 
 should appear. At 1-hour intervals examine the film of oil on 
 the plate by touching it lightly with the finger at points not less 
 than 2.5 cm (1 inch) from the edges. If the film still has the 
 greasy feel of fresh linseed oil, it has not set to touch. If the film 
 feels tacky and adheres to the finger, it is considered to have set 
 to touch. If the finger can be drawn lightly across the film with- 
 out the oil sticking to the finger or the surface being marred by 
 this treatment, the oil is considered dry. In case the test shows 
 time of setting to touch or drying greater than 8 and 18. hours, 
 respectively, a second test shall be run on a different day and the 
 average of the two tests taken. 
 
 (2) NaTuRE oF BAKED Fitm.—Thoroughly clean with benzol a 
 piece of bright sheet metal, either bright sheet iron, tin plate, or 
 terneplate. Shake the sample of drier thoroughly and flow enough 
 on the plate so that a space at least 7.5 em (3 inches) wide is cov- 
 ered. Allow the plate to stand in a vertical position at room tem- 
 perature for 30 minutes and then hang in an oven at a temperature 
 of 100 to 105° C. (212 to 221° F.) for 2 hours. 
 
 Remove the plate from the oven and allow it to stand at room 
 temperature for not less than 1 hour. ‘Test the film of drier with 
 a knife blade at a point not less than 2.5 cm (1 inch) from the edge. 
 If the film powders or particles fly under the knife blade, it will be 
 considered brittle, which will be cause for rejection. 
 
 (e) FLasuH Pornt.—Determine with either the “Tag” or Elliott 
 
 closed-cup tester. The former is preferred.' 
 NN ee ee ee a 
 
 1 Directions for using the Tag tester may be found in A.S. I’. M. Standards D 56-21, and directions for 
 using the Elliott cup in Proceedings A. S. T. M., 1917, pt. x, p. 414. 
 
4 Circular of the Bureau of Standards 
 4. BASIS OF PURCHASE. 
 
 Drier shall be purchased by volume, the unit being a gallon of 
 231 cubic inches at 15.5° C. (60° F.). The volume may be deter- . 
 mined by measure or, in case of large deliveries, it may be easier to 
 determine the net weight and specific gravity at 15.5/15.5° C. 
 (60/60° F.) of the delivery. The weight per gallon in pounds can 
 then be determined by multiplying the specific gravity by 8.33. 
 The net weight in pounds divided by the weight per gallon gives 
 the number of gallons. : ae 
 
 OOOO 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 5 CENTS PER COPY 
 Vv. 
 
DEPARTMENT OF COMMERCE. 
 
 BUREAU OF STANDARDS. 
 
 S. W, STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 No. lL1l. 
 
 [2d edition, Issued June 2z, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 FLAT INTERIOR LITHOPONE PAINT, WHITE 
 AND LIGHT. TINTS. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION No. 21. 
 
 This Specification was officially adopted by the Federal Specifications Board 
 on February 3, 1922, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 
 Page 
 RRP oo, vse icc bee srw h nn ty OTA T CORO, CFE ete se 
 eee ale hy 2 2. 2G. geet Mes te See thy PARA Shas ey oN nae 2 
 2. SEADOTALOrW EXAMINATION: | 6.6... Kis pe ee Gt aE Ee Oe ee Ee 7 3 
 Re RE ME TELE Pogo oc a ih sep yi es Ves iniels <a oF § ZAP nth oceiors-» ha eens Sear HCR 5 
 sak al dec c's Sa we FR wa ee a hb a aly nd OTE e hig Man pe ee 7 
 
 1. GENERAL. 
 
 This specification covers ready-mixed lithopone paints, fre- 
 quently known as flat, washable wall paint, in white and a variety 
 of light tints. Paints under this specification are not intended 
 for outside exposure; they shall dry to dead flat opaque coats 
 that will adhere well to wood, metal, and plaster, stand washing 
 with soap and water, and show no material change in color on 
 exposure to light. 
 
 The paint shall be purchased by volume (231 cubic inches to 
 the gallon). 
 
 63900°—23 
 
2 Circular of the Bureau of Standards 
 
 (a) PrcMENT.—The pigment shall consist of: 
 
 Maximum. Minimum. 
 
 Per cent. | Per cent. 
 80 
 
 Lithopore: 5505 sek eh ie DO Gaye ea ee Bh ac a cre eee oe rn 
 SiN OTIMES,. 0. vccinccd'snd ones os 00s LER OE Rohh Oe BG Chee eRe eee eee 10. AI aie cee 
 Tinting and extending pigments .o255000... 7g cen es teva e Lew len ood dent eee LO Fa uk ota 
 Material soltible in water . 5.o.0.6.e ibis vwicesace bis ay aurm ais msl niece Bie we gia siesta etn i aan 0.8 
 
 a 
 
 ty) sate lithopone used must contain not less than 26 per cent of zinc sulphide and must not darken 
 
 (b) Ligurip.—The liquid portion of the paint shall consist of 
 treated drying oils or varnish, or a mixture thereof, and turpentine 
 or volatile mineral spirits, or a mixture thereof, in such proportions 
 as to insure not less than 25 per cent of nonvolatile vehicle. The 
 nonvolatile vehicle shall dry to a tough and elastic film. 
 
 (c) Patnt.—The paint shall be well ground, shall not settle 
 badly, cake, or thicken in the container, shall be readily broken 
 up with a paddle to a smooth, uniform paint of brushing con- 
 sistency, and shall dry within 18 hours to a dead flat finish without 
 streaking, running, or sagging and free from laps and brush 
 marks. The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller. 
 After drying for not less than five days, marks made on the painted 
 surface with a soft lead pencil (No. 2 Mogul) shall be easily removed 
 by washing with soap and warm water without appreciably 
 marring the paint surface. The weight per gallon shall be not 
 less than 141% pounds. 
 
 The paint shall consist of: 
 
 cry 
 ee ee ee ar 
 
 ee ee ee ee i ee ie i ray 
 
 er 
 Coamwe particles and ‘“‘skins”’ (total residue retained on No. 325 screen based on 
 pigment) 
 
 a er ras 
 
 Notr.—Deliveries will, in general, be sampled and tested by the following methods, 
 but the purchaser reserves the right to use any additional available information to 
 ascettain whether the material meets the specification. 
 
 2. SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible, an original 
 unopened container shall be sent to the laboratory, and when this 
 is for any reason not done the inspector shall determine by thor- 
 
 i 
 
Specification for Flat Intervor Lithopone Paint 3 
 
 ough testing with a paddle or spatula whether the material meets 
 the requirement regarding caking in the container. He shall 
 then thoroughly mix the contents of the container and draw a 
 sample of not less than 5 pounds. This sample shall be placed ina 
 clean, dry metal or glass container, which it must nearly fill. The 
 container shall be closed with a tight cover, sealed, marked, and 
 sent to the laboratory for test with the inspector’s report on caking. 
 
 When requested, a duplicate sample may be taken from the 
 same package and delivered to the seller, and the inspector may — 
 take a third sample to hold for test in case of dispute. 
 
 3. LABORATORY EXAMINATION. 
 
 (a) CAKING IN CONTAINER.—When an original package is re- 
 ceived in the laboratory it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paint must be no more difficult 
 to mix to a uniform consistency than a good grade of flat paint. 
 The paint shall finally be thoroughly mixed, removed from the con- 
 tainer, and the container wiped clean and weighed. This weight 
 subtracted from the weight of the original package gives the net 
 weight of the contents. A portion of the thoroughly mixed paint 
 shall be placed in a clean container and portions for the remaining 
 tests promptly weighed out. 
 
 (b) CoLror.—Place some of the paint on a clean, clear glass plate. 
 Place some of the standard agreed upon beside the sample on the 
 plate, turn the glass over, and compare the colors. 
 
 (c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc gradu- 
 ated flask. Fill to the mark with the thoroughly mixed paint and 
 weigh again. The increase in weight expressed in grams, divided 
 by 100, gives the specific gravity, which multiplied by 8.33 gives 
 the weight in pounds per gallon. 
 
 (d) BRUSHING PROPERTIES, TIME OF DRYING, AND RESISTANCE 
 “TO WASHING.—Brush the well-mixed paint on a suitable panel, 
 which may be ground glass, steel, or well-filled wood. Note 
 whether the paint works satisfactorily under the brush. Place 
 the panel in a vertical position in a well-ventilated room and let it 
 ' stand for 18 hours. The paint should be dry and free from streaks. 
 
 Let the panel stand for five days, then make marks on it with a 
 soft lead pencil (No. 2 Mogul) and wash these marks off with warm 
 (75° C.) distilled water and white floating soap, using a sponge or 
 soft rag. The marks must be removed by this treatment without 
 appreciably marring the paint film. 
 
 Flow a portion of the paint on a clean glass plate. Let dry in 
 a nearly vertical position at room temperature (65° to 100° F‘). 
 The film shall show no streaking or separation within a distance of 
 4 inches from the top. 
 
4 Circular of the Bureau of Standards 
 
 (ec) Fastness To Licut.—Apply a sufficient number of coats 
 of the paint to a ground-glass plate to completely hide the surface, 
 cover half of this painted surface with opaque black paper, and 
 expose indoors in a well-lighted room for five days. Remove the 
 black paper and examine the surface. The exposed portion should 
 be no darker than the portion protected by the black paper. 
 
 (f) WaTER.—Mix 100 g of the paint in a 300 ce flask with 75 
 ce of toluol. Connect with a condenser and distil until about 
 50 ce of distillate has been collected in a graduate. The tem- 
 perature in the flask should be then about 105 to 110° C. The 
 number of cubic centimeters of water collecting under the toluol 
 in the receiver is the percentage of water in the paint. Material 
 complying with the specification should yield less than 1.0 ce. 
 
 (9) VOLATILE THINNER.—Weigh accurately from 3 to 5 g of 
 the paint into a tared flat-bottomed dish about 8 cm in diameter, 
 spreading the paint over the bottom. Heat at 105 to 110° C. for 
 three hours, cool, and weigh. Calculate the loss in weight as 
 percentage of water and volatile thinner, subtract from this the 
 percentage of water (3 (f/)), and report the remainder as oe 
 thinner. 
 
 (h) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 ¢ 
 of the paint into a weighed centrifuge tube. Add 20 to 30 cc of 
 “extraction mixture” (see Reagents), mix thoroughly with a glass 
 rod, wash the rod with more of the extraction mixture, and add 
 sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm 
 with a similar tube or a tube with water. Whirl at a moderate 
 speed until well settled. Decant the clear supernatant liquid. 
 Repeat the extraction twice with 40 cc of extraction mixture and 
 once with 40 cc of ether. After drawing off the ether, set the 
 tube in a beaker of water at about 80° C. or on top of a warm 
 oven for 10 minutes, then in an oven at 105 to 110° C. for two 
 hours. Cool, weigh, and calculate the percentage of pigment.. 
 Grind the pigment to a fine powder, pass through a No. 80 screen 
 to remove any skins, and preserve in a stopper bottle. Pre- 
 serve the extracted vehicle for 3 (J). 
 
 (1) PERCENTAGE OF NONVOLATILE VEHICLE.—Add pisd a the 
 percentages of water (3 (f)), of volatile thinner (3 (g)), and of pig- 
 ment (3 (h)), and subtract the sum from 100. ‘The remainder is 
 the percentage of nonvolatile vehicle, which should be not less 
 than one-third as large as the percentage of volatile thinner. 
 
Specification jor Flat Interior Lithopone Parnt 5 
 
 (7) NATURE OF NONVOLATILE VEHICLE.—Evaporate the ex- 
 tracted vehicle and extraction mixture from 3 (h) to about 5 cc 
 Thoroughly clean with benzol a piece of bright sheet iron, tin 
 plate, or terneplate. Spread a portion of the concentrated ex- 
 tracted vehicle on the sheet of metal, allow to dry for 30 minutes 
 _ at room temperature in a vertical position, bake for three hours 
 at 100 to 110° C. (212 to 221° F.), remove from the oven, and 
 keep at room temperature for three days. Test the film with a 
 knife blade at a place not less than 2.5 cm (1 inch) from the edge. 
 The film should be tough and elastic; if it powders or if particles 
 fly under the test, it will be considered brittle, which will be cause 
 for rejection. ‘The film must also stand light, vigorous rubbing 
 with the finger without powdering or disintegrating. : 
 
 (k) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
 110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
 amount of paint containing 10 g of pigment (see 3 (h)), add 50 cc 
 of kerosene, mix thoroughly, and wash with kerosene through the 
 screen, breaking up all lumps, but not grinding. After washing 
 with kerosene until all but the particles too coarse to pass the 
 screen have been washed through, wash all kerosene from the 
 screen with ether or petroleum ether, heat the screen for one hour 
 at 105 to 110° C., cool, and weigh. 
 
 4. ANALYSIS OF PIGMENT. 
 
 Use the pigment extracted in 3 (h). 
 
 (a) QUALITATIVE ANALYsIS.—Make qualitative analysis fol- 
 lowing ordinary methods. 
 
 (6) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
 ment to a graduated 250 cc flask, add 100 ce of water, boil for 
 five minutes, cool, fill to mark with water, mix, and allow to 
 settle. Pour the supernatant liquid through a dry filter paper 
 and discard the first 20cc. ‘Then evaporate 100 cc of the clear 
 filtrate to dryness in a weighed dish, heat for one hour at 105 to 
 110° C., cool, and weigh. ‘The residue should not exceed 0.008 g. 
 
 (c) BartuM SULPHATE AND SILICEOUS MATERIAL.—Transfer 
 -I g of pigment to a porcelain casserole or dish, moisten with a 
 few drops of alcohol, add 40 cc of hydrochloric acid (1.1, specific 
 gravity), cover, and boil to expel hydrogen sulphide; remove the 
 cover and evaporate to dryness on the steam bath, moisten with 
 hydrochloric acid, dilute with water, filter through paper, and 
 wash with dilute hydrochloric acid and then with hot water until 
 
6 Circular of the Bureau of Standards 
 
 the washings are free from zinc and chlorine. Ignite and weigh 
 the residue, which will be barium sulphate and siliceous material. 
 
 Mix the ignited residue with about 10 times its weight of anhy- 
 drous sodium carbonate (grind the mixture in an agate mortar if 
 necessary), fuse the mixture in a covered platinum crucible, heat- 
 ing about one hour. Let cool, place the crucible and cover in a 
 250 cc beaker, add about 100 cc of water, and heat until the 
 melt is disintegrated. Filter on paper (leaving the crucible and 
 cover in the beaker) and wash the beaker and filter thoroughly 
 with hot water to remove soluble sulphates. Place the beaker 
 containing the crucible and cover under the funnel, pierce the 
 filter with a glass rod, and wash the carbonate residue into the 
 beaker by means of a jet of hot water. Wash the paper with 
 hot dilute hydrochloric acid (1:1), and then with hot water. If 
 the carbonate residue is not completely dissolved, add sufficient 
 dilute hydrochloric acid to effect solution, and remove the crucible 
 and cover, washing them with a jet of water. Heat the solution 
 to boiling and add 10 to 15 cc of dilute sulphuric acid, and 
 continue the boiling for ro or 15 minutes longer. Let the pre- 
 cipitate settle, filter on a weighed Gooch crucible, wash with hot 
 water, ignite, cool, and weigh as BaSO,. Subtract from the re- 
 sult of the previous determination to obtain the siliceous material. 
 
 (dq) Tota, Zinc CALCULATED Aas ZINC OxmpE.—With material 
 containing no interfering elements (iron, for example) weigh ac- 
 curately about 1 g of pigment, transfer to a 400 cc beaker, 
 moisten with alcohol, add 30 cc of hydrochloric acid (1:2), 
 boil for two to three minutes, add 200 cc of water and a small 
 piece of litmus paper; add strong ammonia until slightly alka- 
 line, render just acid with hydrochloric acid, then add 3 ec of 
 strong hydrochloric acid, heat nearly to boiling, and titrate with 
 standard ferrocyanide as in standardizing that solution (see 
 Reagents). Calculate total zinc as zinc oxide. 
 
 When iron or other interfering elements are present (see 4 (a) ), 
 take the filtrate containing the zinc from 4 (c), add a slight excess 
 of bromine water and 2 g ammonium chloride, heat to nearly 
 boiling, add an excess of ammonia, heat for about two minutes, 
 filter, dissolve the precipitate in hydrochloric acid, add 2 g of 
 ammonium chloride, and reprecipitate with ammonia as above. 
 Filter, wash the precipitate with hot 2 per cent ammonium-chloride 
 solution, unite the two filtrates, and determine zinc as above. 
 
Specification for Flat Intervor Lithopone Paint 7 
 
 (e) Zinc OxipE.—Weigh accurately 2.5 g of pigment, transfer 
 to a 250 cc graduated flask, moisten with a few drops of alcohol, 
 add about 200 ce of 1 to 3 per cent acetic acid, shake vigorously 
 and let stand for 30 minutes, shaking once every five minutes. 
 Fill to the mark with 1 to 3 per cent acetic acid, mix, filter through 
 a dry paper, discard the first 25 cc and determine zine in 100 cc 
 of the filtrate (corresponding to 1 g) asin 4 (d). Calculate the 
 percentage of zinc oxide. 
 
 ({) CALCULATIONS.—Subtract the percentage of zinc oxide 
 (4 (e) ) from the percentage of total zine as zinc oxide (4 (d) ) and 
 multiply the remainder by 1.2 to convert to percentage of zinc 
 sulphide. In case the percentage of barium sulphate (4 (c) ) is 
 not more than 2.86 times as great as the percentage of zinc sul- 
 phide, add the two together and call the sum the percentage of 
 lithopone. If the percentage of barium sulphate is greater than 
 
 _ this amount, take 2.86 times the percentage of zinc sulphide as 
 
 the percentage of barium sulphate to be included in the percentage 
 oi lithopone and include the remainder in the percentage of tinting 
 and extending pigments. Subtract the sum of the percentage of 
 zine oxide (4 (e) ), lithopone, and matter soluble in water (4 (0) ) 
 from 100. Call the remainder percentage of tinting and extending 
 pigments. ; 
 
 5. REAGENTS. 
 
 (a) EXTRACTION MIXTURE.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 1 volume acetone. 
 
 (6) ONE To THREE PER CENT AceETIC Acip.—Dilute 20 cc 
 glacial acetic acid to 1,000 cc with distilled water. 
 
 (c) URANYL INDICATOR FOR Zinc ‘JITRATION.—A 5 per cent 
 solution of uranyl nitrate in water or a 5 per cent solution of 
 uranyl acetate in water made slightly acid with acetic acid. 
 
 (d) STANDARD PoTasstuM FERROCYANIDE.—Dissolve 22 g of 
 the pure salt in water and dilute to 1,000 cc. To standardize, 
 transfer about 0.2 g (accurately weighed) of pure metallic zinc or 
 freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
 10 ce of hydrochloric acid and 20cc of water. Drop in a small 
 piece of litmus paper, add ammonium hydroxide until slightly 
 alkaline, then add hydrochloric acid until just acid, and then 3 cc. 
 
8 Circular of the Bureau of Standards 
 
 of strong hydrochloric acid. Dilute to about 250 ce with hot 
 water and heat nearly to boiling. Run in the ferrocyanide solu- 
 tion slowly from a burette with constant stirring until a drop 
 tested on a white porcelain plate with a drop of the uranyl indi- 
 cator shows a brown tinge after standing one minute. A blank 
 should be run with the same amounts of reagents and water as in 
 the standardization. The amount of ferrocyanide solution re- 
 quired for the blank should be subtracted from the amounts used 
 in standardization and in titration of the sample. The standardi- 
 zation must be made under the same conditions of temperature, 
 volume, and acidity as obtain when the sample is titrated. 
 
 | ce aS SRS SSN ST PE SE TNS CAREERS Treen Saeraaerestar Se | 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 AT 
 5 CENTS PER COPY 
 
 V 
 
hie ae) Wg Sek 
 
 DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 S. W. STRATTON, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS. 
 
 No. 117. 
 
 [2d edition. Issued July 3, 1922.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 
 INTERIOR VARNISH. 
 FEDERAL SPECIFICATIONS BOARD. 
 - STANDARD SPECIFICATION No. 22. 
 
 Thit Specification was officially adopted by the Federal Specifications Board on 
 February 3, 1922, for the use of the Departments and Independent Establish- 
 - ments of the Government in the purchase of materials covered by it. 
 
 CONTENTS. 
 : Page 
 By) ae ee OT CE Ree ae TRE RANT MERGE ON I 
 Se al I Nh cg cd acti niaaen ped Wa Rn din edie Woks aig ok Deke 2 
 ees 2 elaiyad AIR Geablalis Iaiah hal Mi r giaae ceihingrll Naha Rae a a ee alee 2 
 Peerensupenee. folie. Tie FG TO. i. CORLL PO AT a 6 
 1. GENERAL. 
 
 The varnish shall be suitable for general interior use, both 
 rubbed and unrubbed finish, including floors. It must be ca- 
 pable of easy application with a brush in the ordinary manner 
 according to the rules of good standard practice, must flow out 
 to a good level coat free from runs, sags, pits, or other defects, and 
 dry with reasonable promptness to a hard, somewhat elastic glossy 
 coating which can be rubbed in 48 hours or less. The manufac- 
 turer is given wide latitude in the selection of raw materials and 
 processes of manufacture, so that he may produce a varnish of 
 the highest quality. The varnish must meet the following 
 requirements: 
 
 APPEARANCE.—Clear and transparent. 
 
 63901°—23 
 
2 Circular of the Bureau of Standards 
 
 CoLtor.—Not darker than a solution of 3 g of potassium dichro- 
 mate in 100 cc of pure sulphuric acid, specific BrAyEy, 1.84. 
 
 FLASH POINT (CLOSED-CcUP).—Not below 30° C. (85° F.). 
 
 NONVOLATILE MatTER.—Not less than 45 per cent by weight. 
 
 Set to Toucu.—In not more than 4 hours. 
 
 Dry Harp.—In not more than 24 hours. 
 
 Dry To Rus.—In not more than 48 hours. 
 
 TOUGHNESS.—Film on metal must stand rapid bending over a 
 rod 3 mm (% inch) in diameter. 
 
 WorKING PROPERTIES.—Must have good brushing, flowing, 
 covering, leveling, and rubbing properties; and must show no 
 impairment of luster or other defect when used where natural or 
 illuminating gases are burned or when subjected to air currents 
 during the process of drying or application. . 
 
 WATER RESISTANCE.—The dried film must ghee Sate 
 
 of cold water for not less than 18 hours without whitening or 
 showing other visible defect. | 
 
 Note.—Deliveries will, in general, be sampled and tested, by the following methods, but the pur- 
 chaser reserves the right to use any available information to ascertain whether the material meets ie 
 
 specification. 
 2. SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible, an original un- 
 opened container shall be sent to the laboratory, and when for 
 any reason this is not done, the inspector shall thoroughly mix 
 the contents of the container sampled, transfer not less than 1 
 quart to a clean dry glass bottle or tin can which must be nearly 
 filled with the sample, securely stoppered with a new clean cork 
 or well-fitting cover, or cap, sealed, and distinctly hee sh eg 
 inspector. 
 
 The inspector should take a duplicate fou the container 
 sampled to be held for check in case of dispute, esi bidet set 
 
 quested, should take a sample for the seller. 
 
 3. LABORAT ORY EXAMINATION. 
 
 The tin panels used in the following tests ‘shall be cut raves 
 
 bright tin plate weighing not more than 25 g nor less than’ 19 
 g per square decimeter (0.51 to 0.39 pound per square foot). 
 (Commercial No. 31 gage bright tin plate should weigh about 
 
 0.44 pound per square foot. It is important that = tin Meg 2c 
 
 used shall be within the limits set.) 
 
 a 
 
Specification for Intertor Varnish 3 
 
 (a) APPEARANCE.—Pour some of the thoroughly mixed sam- 
 ple into a clear glass bottle or test tube and examine by trans- 
 mitted light. The varnish must be clear and transparent. 
 
 (6) CoLlor.—Prepare a standard color solution by dissolving 
 3 g of pure powdered potassium dichromate in 100 cc of pure 
 concentrated sulphuric acid of specific gravity 1.84. Gentle 
 heat may be used if necessary to perfect the solution of the di1- 
 chromate. The standard color solution and a sample of the 
 varnish to be tested shall be placed in clear, thin-walled glass 
 
 tubes of the same diameter. The color comparison shall be 
 
 made by placing the tubes close together and looking through 
 them by transmitted Ben The tubes used for this test should 
 be 1.5 to 2.0 cm (5% to 1% inch) in diameter and shall be filled to 
 a depth of at least 2.5 we (1 inch). (Since the potassium di- 
 chromate-sulphuric acid must be freshly made for this color 
 comparison, it is frequently more convenient to compare samples 
 with a permanently sealed tube of varnish which has. previously 
 been found to be slightly lighter in color than the standard solu- 
 tion of 3 g dichromate in sulphuric acid. When samples are 
 
 found to be darker than this standard tube of varnish, the di- 
 
 chromate standard should be made up for final decision.) 
 
 (c) FuasH Pornt.—Determine with either the Tag or Elliott 
 closed-cup tester. The former is preferred.’ 
 
 (d) NONVOLATILE MATTER.—Place a portion of the sample in a 
 
 ‘stoppered bottle or weighing pipette. Weigh container and sam- 
 ple. Transfer about 1.5 g of the sample to a weighed flat-bot- 
 
 tomed metal dish about 8 cm diameter (a friction-top can plug). 
 Weigh container again and by difference calculate the exact weight 
 
 of the portion of sample transferred to the weighed dish. Heat 
 
 dish and contents in an oven maintained at 105 to 110° C. (221 to 
 230° F.) for three hours. Cooland weigh. From the weight of the 
 
 residue left in the dish and weight of the sample taken, calculate 
 
 the percentage of nonvolatile residue. 
 
 (e) Dryinc Time.—Pour the varnish on a clean glass or bright 
 tin plate not less than 15 cm (6 inches) long and 10 cm (4 inches) 
 wide. Place the plate in a nearly vertical position in a well- 
 
 ventilated room but notin the direct rays of the sun. The tempera- 
 
 ture of the room should be from 21 to 32°C. (7o to 90° F.).. The 
 
 film is tested at points not less than 2.5 cm (1 inch) from the edges 
 of the film by touching lightly with the finger. The varnish is 
 
 1 Direotions for using the Tag tester may be found in A. S. T. M. Standards D died and difections Le 
 
 using the Elliott cup in Proceedings A. S. T.M., 1917, pt. 1, D. 414. 
 
4 Circular of the Bureau of Standards 
 
 considered to have set to touch when gentle pressure of the finger 
 shows a tacky condition but none of the varnish adheres to the 
 finger. The varnish is considered to have dried hard when the 
 pressure that can be exerted between the thumb and finger does 
 not move the film or leave a mark which remains noticeable after 
 the spot is lightly polished. If rapid light rubbing breaks the 
 surface, the sample is considered not to have satisfactorily dried 
 hard. In case the test shows time of setting to touch or drying 
 hard more than 4 and 24 hours, respectively, two additional tests 
 shall be run on different days and if the varnish does not meet the 
 above drying and hardening requirements on both of these addi- 
 tional tests it shall be considered unsatisfactory. In cases where 
 different laboratories fail to agree on the drying test, due to 
 different atmospheric conditions, and umpire tests are necessary, 
 such tests shall be made in a well-ventilated room maintained at 
 a temperature of 70° F. and relative humidity of 65 Per cent 
 saturation. 
 
 ({) ToucHnEss.—Thoroughly clean with benzaly’ a year’ of 
 bright tin 7.5 by 13 cm (about 3 by 5 inches). Flow the varnish 
 on one side of the tin plate and set in a vertical position in a well- 
 ventilated room, not in the direct rays of the sun, ata steht an inte 
 not below 21° C. (70° F.). 
 
 After the varnish on the tin plate has dried for 48 hours ihe 
 to a temperature between 21 and 24° C. (70 to 75° F.), and with 
 the varnish film on the outside, bend rapidly over a rod 3 mm 
 (% inch) in diameter. The film must show no evidence of crack- 
 ing or flaking. 
 
 (g) WATER RESISTANCE.—Prepare a panel as in ay sald let 
 it dry in a well-ventilated room for 48 hours. Place the panel in 
 a beaker containing about 2.5 inches of distilled water at room tem- 
 perature (immersing the end of the panel which was uppermost 
 during the drying period) and leave in water for 18 hours. The 
 varnish shall show no whitening and no more than a very slight 
 dulling when observed after removing the panel co feaes water 
 and drying for 2 hours. y sud 
 
 (h) FLowInGc AND RUBBING PROPERTIES.—I Ronehatihe alin 
 with benzol a glass plate about 15 by 20cm (6 by 8inches). Flow 
 
 .°» the varnish so as to cover entirely one side of the plate and stand 
 
 in a nearly vertical position with the long edge horizontal for 8 
 minutes. ‘Then draw lightly a 25 mm (1 inch) section of a hard- 
 rubber comb (having 8 to 10 teeth to the centimeter) horizontally 
 across the varnish surface, first 2 cm from the bottom and then 2em 
 
Specification for Intertor Varnish 5 
 
 from the top of the plate. Let panel stand in the same position 
 for 20 minutes longer, then lay flat. An exaggerated condition of 
 a dusty room shall be created by rubbing some cotton batting 
 between the hands immediately over the panel. Let panel dry 
 for a\ total of 48 hours in a well-ventilated room. If the comb 
 marks show at this time, the varnish shall be rejected. If no 
 comb marks show, the surface shall then be rubbed with pumice 
 flour, water, and a felt pad with long, even, firm strokes back and 
 forth in one or another direction, but not in circles, until every 
 portion of the panel has been rubbed. Most.of the pumice will 
 then be removed from the pad and panel, and the varnish film 
 given a ‘‘water rub’”’ with the pad. 
 
 A satisfactory rubbing varnish in the above test will yield a 
 smooth, dull film even at those places where the dust particles 
 have been encrusted in the film, and shall show no spots where 
 the pumice has been ground into and become attached to the film, 
 nor show any other evidence of gumming. No sweating shall 
 occur anywhere on the film in #8 hours after rubbing. 
 
 _ (4) Gas Trest.—Apparatus.—The necessary apparatus consists 
 of a glass bell jar approximately 20 cm (8 inches) in diameter and 
 30 cm (12 inches) in height, inside dimensions, having a ground- 
 glass rim; a ground-glass base plate of suitable size; a small, 
 kerosene glowlamp without chimney, or a small alcohol lamp 
 filled with kerosene, using a round wick not over 6 mm (1% inch) 
 in diameter and adjusted to give a flame 2 cm (4/; inch) in height. 
 A wire or a light wooden frame is fitted inside the jar and provided 
 with a support for holding a disk of tin plate 15 cm (6 inches) in 
 diameter in a horizontal position 5 cm (2 inches) above the wick 
 of the lamp. The frame must also be provided with several other 
 supports above this disk for holding in a horizontal position the 
 various varnished panels under test. The test panels consist of 
 semicircular pieces of bright tin plate approximately 15 cm (6 
 inches) in diameter. | 
 
 - The form and arrangement of the above apparatus is designed 
 to provide an even distribution of the products of combustion 
 over the test panels. 
 
 Method.—First determine the normal time required for the 
 varnish under examination to set to touch at room temperature. 
 Divide this time by five to arrive at the different drying periods 
 at which the varnish is to be tested in the gastester. Thus, if a 
 varnish sets to touch in five hours, samples should be tested for 
 resistance to gas at drying periods of one, two, three, and four 
 
6 Circular of the Bureau of Standards 
 
 hours; it is needless to use the fifth or five-hour period for the 
 above varnish, as a varnish which has set to touch is practically 
 immune to injury from -gas fumes. Similarly a varnish which 
 sets to touch in one hour should be tested for resistance to gas at 
 drying periods of 12, 24, 36, and 48 minutes. 
 
 Example.—A vases which sets to touch in five hours i is tested 
 as follows: 
 
 First, clean two of the semicircular, bright, tin-plate panels 
 carefully with benzol. Flow the varnish on one-half of panel 
 No. 1 at, say, 10 a. m., and allow to drain in a nearly vertical 
 position at room temperature. At 11 a. m., flow the varnish on 
 the other half of panel No. 1; allow to drain as before. At 12 m. 
 varnish one-half of panel No. 2, and at 1 p. m. varnish the other 
 half, as above. At 2p. m. place the two panels close together in 
 a horizontal position on the upper supports of the frame. Light 
 the lamp and set it under the circular tin. Place the bell jar in 
 position, centering it as nearly as possible, properly seated on the 
 ground-glass plate. If the chamber is tight and lamp properly 
 adjusted, the flame will be extinguished in about four minutes. 
 After the panels have been in the chamber for half an hour, 
 remove the bell jar and examine the ee = for Bes 
 effects. | 
 \ The varnish on all four sections hold remain bright ait aaa 
 without trace of Sgt ony he ‘crow’s ities) Wipe or’ other 
 defects. FATE G EL? 
 
 4. BASIS OF PURCHASE, 
 
 Varnish shall be Pisa by volume, ‘the unit being a gallon 
 éf 231 cubic inches at 15.5°C. (60°F). The volume may | be deter- 
 mined by measure, or, in case of large deliveries, it may be easier 
 to determine the net weight and specific gravity at 15.5 /15. 5°. 
 (60/60° F.) of the delivery. ‘The weight per gallon in pounds can 
 then be determined by multiplying the specific gravity by 8.33. 
 The net weight in pounds divided Phi the ment per a gives 
 the number of gallons. 
 
 ADDITIONAL COPIES . 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS . . 
 | GOVERNMENT PRINTING OFFICE, 
 WABHINGTON, B.C. 
 5 CENTS PER COPY 
 ® c Vv : 
 
 : 7 ‘ sage a4 ove Ot eyricieresy 
 WASHINGTON : GOVERNMENT PRINTING OFFICE : 1922 
 
5 aie: 
 we 
 
U. S. Gov't 
 Standard 
 Specification, 
 
 No. 66. 
 
 DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 George K. Burgess, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, NO. 146. 
 
 [Issued September 25, 1923.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 
 WATER-RESISTING RED ENAMEL. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 66. 
 
 This specification was officially adopted by the Federal Specifications Board 
 on September |, 1923, for the use of the Departments and Independent Estab- 
 lishments of the Government in the purchase of water-resisting red enamel. 
 
 CONTENTS. : 
 : Page 
 Se eres vine ye ce uae maces fies aedess <s I 
 Te a vat ens ees ces Ss Pee Ber ears oe ete er Seg ATER es 2 
 Siiliaborstoryoexbmiination : (22256520. . . aloes - aes Leon. 3 ba - 20) - 2 
 Bp Dania Gh DUPCIORE farses pre oh, s aes oon a0 owrie cn con babar bh esendes meh epentn 6 
 1, GENERAL. 
 
 The material desired under this specification is an extremely 
 durable, highest quality red enamel, suitable primarily for outside 
 use. It should be made by grinding pure high color strength 
 toluidine red toner (metanitro-paratoluidine-azo-betanaphthol), 
 free from any base or substratum, with the very best water- 
 resisting long oil spar varnish. The color and hiding power 
 when specified shall be equal to those of a sample mutually 
 agreed upon by buyer and seller. It must meet the following 
 requirements: | 
 
 WEIGHT PER GALLON.—Not less than 734 pounds. 
 
 PIGMENT.—Not less than 6 per cent by weight; pigment to be 
 composed entirely of pure high color strength toluidine red 
 toner, free from any other organic coloring matter, base, or 
 
 substratum. 
 61692°—23 
 
2 Circular of the Bureau of Standards. 
 
 COARSE PARTICLES AND ‘“‘SKINS”’ (total residue retained on No. 
 325 sieve).—Not more than 0.5 per cent. 
 
 NONVOLATILE MATTER.—Not less than 60 per cent by weight. 
 
 SET TO Toucn.—In not more than 18 hours. 
 
 Dry Harp AND ToucH:—In not more than 48 hours. 
 
 WorKING PROPERTIES.—Enamel must have good brushing, 
 flowing, covering, and leveling properties and must not cake in 
 the container. 
 
 WATER RESISTANCE.—Dried film must withstand ae water for 
 
 18 hours and boiling water for 15 minutes verte whitening, 
 dulling, or change in color. 
 
 TOUGHNESS:—Enamel must pass a 50 per cent Kauri reduction 
 test'at 24° Oye Me. 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available information to ascertain whether the material meets the 
 specification. 
 
 2. SAMPLING. 
 
 It is ; mutually agreed by buyer. and seller that a. single ues 
 out of each lot of not more than 1,000 packages be taken as repre- 
 sentative of the whole. Whenever possible, an original unopened 
 container shall be sent to the laboratory, and when for any rea- 
 tents of the container sampled, transfer not less than 1 raatt 
 to a clean, dry glass bottle or tin can, which must be nearly filled 
 with the sample, securely stoppered with a new, clean cork or well- 
 fitting cover or cap, sealed and distinctly labeled by the inspector. 
 The inspector should take a duplicate from the container sampled 
 to be held for check in case of dispute, and, when requested, 
 should take a sample for the seller. HE RSS 
 
 3, LABORATORY EXAMINATION. 
 
 The tin panels used in the following tests shall all be cut: tiem 
 bright tin plate weighing not more than 25 nor less than 19 g per 
 square decimeter (0.51 to 0.39 pound per square foot) (Com- 
 mercial No. 31 gauge bright tin plate should weigh ‘about ‘0.44 
 pound per square foot. It is important that! the tin plate’ used 
 shall be within the limits'set.) The panels shall be about 7.5 by 
 13 cm (3 by 5 mches) and must be panei gi = 
 benzol immediately before using. ) ! i T9001 
 
 (a) CAKING IN CONTAINER AND WoRiING. PROPER TAG, “when 
 an original package is received in the laboratory, it shall be 
 
Specification for Water-Resisting Red Enamel. 3 
 
 weighed, opened, and stirred with a stiff spatula or paddle. ‘The 
 enamel must be no more difficult to break up than a normal good 
 grade of enamel paint. The enamel shall finally be thoroughly 
 mixed, removed from the container, and the container wiped 
 clean and weighed. This weight subtracted from the weight of 
 the original package gives the net weight of the contents. Apply 
 some of the thoroughly mixed enamel, both by brushing and 
 flowing, to clean glass plates. It should work easily under the 
 brush. Dry both plates in a nearly vertical position. They 
 should both dry without streaking, separating, or showing brush 
 marks. A portion of thoroughly mixed enamel shall be placed 
 in a clean container and the portions for the remaining tests 
 promptly weighed out. 
 
 (b) CoLOR AND Hipinc PowEr.—Place some of the enamel on a 
 clean, clear glass plate. Place some of the standard agreed upon 
 beside the sample on the plate, turn the glass over, and compare 
 the colors by transmitted and reflected light. 
 
 (c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc gradu- 
 ated flask. Fill to the mark with the thoroughly mixed enamel and 
 weigh again. The increase in weight expressed in grams, divided 
 by 100, gives the specific gravity, which, multiplied by 8.33, 
 gives the weight in pounds per gallon. 
 
 (d) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
 110° C. a No. 325 sieve, cool, and weigh accurately. Weigh 
 accurately about 50 g of the enamel, add 100 cc of kerosene, mix 
 thoroughly, and wash with kerosene through the sieve, breaking 
 up all lumps, but not. grinding. After washing with kerosene 
 until all but the particles too coarse to pass the sieve have been 
 washed through wash all kerosene from the sieve with ether or 
 - petroleum ether, heat the sieve for one hour at 105 to 110° C., 
 cool, and weigh. 
 
 (e) PIGMENT. — Qualitative examination.—Pour about 1 g of the 
 thoroughly stirred enamel, previously strained through a No. 200 
 sieve into a 50 cc beaker. Add about 4o ce of chloroform 
 (U. S. P.) and warm on the steam bath, stirring with a glass rod. 
 A clear orange-red solution should result in a few minutes. Take 
 another portion of the enamel and spread it with a spatula on a 
 smooth, white surface, such as a piece of milk glass. ‘Touch a few 
 drops of alcoholic sodium hydroxide solution to the center of the 
 film and rub well with a glass spatula. There should be no change 
 in color.’ | 
 
 1 The presence of para nitraniline red is indicated by a violet color. 
 
4 Circular of the Bureau of Standards. 
 
 Quantitative determination.—Weigh 1 g (+ 10 mg) of the 
 enamel and 6g (+ 10 mg) of pure zinc oxide, place on a large 
 glass plate, add.2 cc of linseed oil and rub up with a flat-bottomed 
 glass pestle or muller, grinding with a circular motion 50 times. 
 Gather up with a sharp-edge spatula and grind out twice more 
 in like manner, giving the pestle a uniform pressure. Next 
 weigh to + 1 mg an amount of pure high color strength toluidine 
 red toner equal to 6 per cent of the weight of enamel taken, 
 add 4 drops of linseed oil and rub up with the glass pestle. 
 Then add 6 g of pure zinc oxide and 2 cc of linseed oil and treat 
 in exactly the same manner as described above. Transfer por- 
 tions of each paste to a clean microscope slide quite close together, 
 and then draw a palette knife across both samples, so as to make 
 them meet in a line. Compare the tints as shown on both sides 
 of the glass. The color of the sample tested shall be not less 
 than that of the selected standard, and the tone shall be not 
 materially different from it. 
 
 ({) NONVOLATILE MATTER.—Place a portion of the sample in a 
 stoppered bottle or weighing pipette. Weigh container and sam- 
 ple. Transfer about 1.5 g of the sample to a weighed flat-bot- 
 tomed metal dish about 8 cm in diameter (a friction-top can plug). 
 Weigh container again and by difference calculate the exact weight 
 of the portion of sample transferred to the weighed dish. Heat 
 dish and contents in an oven maintained at 105 to 110° C. (221 to 
 230° F.) for three hours. Cool and weigh. From the weight of 
 the residue left in the dish and weight of the sample taken calcu- 
 late the percentage of nonvolatile residue. | 
 
 (g) Dryinc TrmzE.—Pour the enamel on one of the tin panels 
 described above. Place the panel in a nearly vertical position in 
 a well-ventilated room, but not in the direct rays of the sun. The 
 atmosphere of this room must be free from products of combus- 
 tion or laboratory fumes. The temperature of the room should 
 be from 21 to 32° C. (7o to 90° F.).* The film is tested at points 
 not less than 2.5 em (1 inch) from the edges of the film by touch- 
 ing lightly with the finger. ‘The enamel is considered to have set to 
 touch when gentle pressure of the finger shows a tacky condition, 
 but none of the enamel adheres to the finger. The enamel is con- 
 sidered to have dried hard when the: pressure that can be exerted 
 between the thumb and finger does not move the film or leave a 
 mark which remains noticeable after the spot is lightly polished. 
 If rapid, light rubbing breaks the surface, the sample is considered 
 not to have satisfactorily dried hard. In case the test shows time 
 of setting to touch or drying hard more than 18 and 48 hours, 
 
: ; 
 ; 
 a 
 | 
 . 
 
 Specification for Water-Resistung Red Enamel. 5 
 
 respectively, two additional tests shall be run on different days, 
 and if the enamel does not meet the above drying and hardening 
 requirements on both of these additional tests it shall be con- 
 sidered unsatisfactory. In cases where different laboratories fail 
 to agree on the drying test, due to different atmospheric condi- 
 tions, and umpire tests are necessary, such tests shall be made in 
 a well-ventilated room maintained at a temperature of 70° F’. and 
 
 - relative humidity of 65 per cent saturation. 
 
 (h) WatER RESISTANCE.—Pour the enamel on two of.the tin 
 panels described above and allow to dry under the conditions 
 described in paragraph (g) for 48 hours. Place one of these panels 
 in a beaker containing about 2.5 inches of distilled water at room 
 temperature (immersing the end of the panel which was upper- 
 most during the drying period) and leave in water for 18 hours. 
 The enamel shall show no whitening and no more than very. slight 
 dulling either when observed immediately after removing from the 
 water or after drying for 2 hours. Place the other panel in a 
 beaker containing about 2.5 inches of boiling distilled water (im- 
 mersing the end of the panel which was uppermost during the 
 drying period) and allow to remain in the boiling water for 15 
 minutes. ‘The enamel shall show no whitening, no more than a 
 very slight dulling, and no material change in color, either when 
 observed immediately after removing from the water or after 
 drying for 2 hours. | 
 
 (4) ToucHNEss.—The toughness of the enamel is determined 
 by the Kauri reduction test, as follows: By proportionately reduc- 
 ing its toughness by the addition of a standard solution of ‘‘run- 
 Kauri” gum in pure spirits of turpentine. 
 
 (1) Preparation of the “run Kaurt.”’—Arrange a distillation 
 flask, water-cooled condenser, and a tared receiver on a balance. 
 Place in the flask about one-third of its volumetric capacity 
 of clear, bright hard pieces of Kauri gum broken to pea size. 
 Carefully melt and distil until 25 per cent, by weight, of the gum 
 taken is collected in the tared receiver. (At the end of the distil- 
 lation the thermometer in the distillation flask with the bulb at 
 the level of the discharging point of the flask should register about 
 316° C. (600° F.).) Pour the residue into a clean pan, and when 
 cold break up into small pieces. 
 
 (2) Preparation of standard ‘“ryn-Kaurt’’ solution.—Place a 
 quantity of the small broken pieces of run-Kauri, together with 
 twice its weight of freshly redistilled spirits of turpentine, using 
 
 ‘only that portion distilling over between 153 and 170° C. (308 
 
 and 338° F.) in a carefully tared beaker. Dissolve by heating 
 
6 Circular of the Bureau of Standards. 
 
 to a temperature of about 149° C. (300° F.) and bring back to: 
 correct weight when cold by the addition of the amount of redis- 
 tilled spirits of turpentine necessary to replace the loss by evapora- 
 tion during the dissolving of the gum. 
 
 (3) Reduction of the enamel.—Having carefully determined the 
 nonvolatile content of the enamel according to the method under 
 paragraph (f) of this specification, take 100 g of the enamel and 
 add to it an amount of the standard run-Kauri solution equiva- 
 lent to 50 per cent, by weight, of the nonvolatile matter in the 
 enamel. Mix the enamel and the solution thoroughly. : 
 
 (4) Application of the enamel.—Flow a coat of the enamel thus 
 reduced on one of the tin panels described above and let stand 
 in a nearly vertical position at room temperature for one hour. 
 Next place the panel in a horizontal position in a properly venti- 
 lated oven and bake for five hours at 95 to 100° C. Remove the 
 panel from the oven and allow to cool at room esa stoic prefer- 
 ably 24° C. (75° F.) for one hour. 
 
 (5) Bending the Panel: —Place the panel with the enameled side 
 uppermost over a 3-mm (3% inch) rod, held firmly by suitable 
 supports, at a point equally distant from the ‘top and bottom 
 edges of the panel and bend the panel double rapidly. The enamel 
 must show no cracking whatsoever at the point of bending. For 
 accurate results the bending of the panel should always be done 
 at 24°C. (75° F.), for a lowering of the temperature will lower the 
 percentage of reduction that the enamel will stand without cracking, 
 while an increase in the temperature increases the seers 2 of 
 reduction that the enamel will stand. | 
 
 4. BASIS OF PURCHASE... 
 
 Enamel shall be purchased by volume, the unit being a gallon 
 of 231 cubic inches at. 15.5° C. (60° F.). The volume may be 
 determined by measure or, in case of large deliveries, it may be 
 easier to determine the net weight and specific gravity at 15.5/15.5° 
 C. (60/60° F.) of the delivery. The weight per gallon in pounds 
 can then be determined by multiplying the specific gravity by 8. 33. 
 The net weight in pounds divided by the weight per gallon gives 
 the number of gallons. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 5s CENTS PER COPY 
 
 PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
 COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY IT, 1922 
 
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U. “Ss. Gov't 
 Standard 
 
 Specification, 
 No. 67. 
 
 DEPARTMENT OF COMMERCE. 
 
 BUREAU OF STANDARDS. 
 
 George K. Burgess, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS NO. 147. 
 (Issued September 19, 1923.) 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 GLOSS INTERIOR LITHOPONE PAINT, WHITE AND 
 LIGHT TINTS. 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION NO. 67. 
 
 This specification was officially adopted by the Federal Specifications Board 
 on September |, 1923, for the use of the Departments and Independent Establish- 
 ments of the Government in the purchase of gloss interior lithopone paint, white 
 and light tints. 
 
 | CONTENTS. 
 Page. 
 PRET BD ie PN gh gO 8 EE ols AG 8s Oe gle OOP Mr as be cle Cee Be ee est I 
 aac inane rely emetiraie, Seainr ia Mire aaticic artes I ae My a ae ea 2 
 EE Oe 2 0 Rn eR RR ar NET A NE NR 3 
 INR feos acca Me wah so pale ate leorngieg als be oa ks eae es 6 
 Cy otc) 2 QR ean ie nmmaor enon anny erin nc oor ir ka 8 
 
 1. GENERAL. 
 
 This specification covers ready-mixed lithopone paints, fre- 
 quently known as gloss mill white, in white and a variety of light 
 tints. Paints under this specification are not intended for out- 
 side exposure. They shall dry to gloss opaque coats that will 
 adhere well to wood, metal, and plaster, stand washing with soap 
 and water, and show no material change in color on exposure to 
 light or material yellowing when kept in the dark. 
 
 The paint shall be purchased by volume (231 cubic inches to 
 the gallon). 
 
 61693°—23 x 
 
2 Circular of the Bureau of Standards. | 
 
 (a) P1GMENT.—The pigment shall consist of : 
 
 Maximum.| Minimum. 
 
 Per cent. | Per ewe 
 
 Tlthronane dae oa ce cca cnnsccuseceuneceascuseneveneces anes hau e ee smn 0 ah an ama a ee a 
 
 TFT OEMS oo as tga Gh ne 6 Wh ded wow did.in lal bulla Awe Ys alg ptm ribs atk ln ie 20 
 Tinting and extending pigments... ........6.c.c cee cece cece tees ect eeasee bese nine 2s fe Mee ere Ope es 
 Material soluble in Water... cc ccc a ccwsws wincicndinnw cbegsdune cn ee ele she  teeuen 6: 6 ie oa Ponet eaek 
 
 a a Ov enn een een mmceeete me BI 
 1 The lithopone used must contain not less than 26 per cent of zine sulphide and must not darken on . 
 exposure. 
 
 In no case shall the sum of zinc oxide and lithopone be less 
 than 95 per cent. 
 
 (b) Liourw.—The liquid portion of the paint shall consist of 
 treated drying oils or varnish, or a mixture thereof, and turpen- 
 tine or volatile minera! spirits, or a mixture thereof, in such pro- 
 portions as to insure not less than 60 per cent of nonvolatile 
 vehicle. The nonvolatile vehicle-shall dry to a ge atl elastic 
 film. el 
 
 (c) Parnt.—The paint shall be-well ee ote oe "gets 
 badly, cake, or thicken in the container, shall be readily broken 
 up with a paddle to a smooth, uniform paint of brushing consist- 
 ency, and shall dry within 24 hours to a varnish gloss finish with- 
 out streaking, running, or sagging, and free from laps and brush 
 marks. ‘The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller, 
 After drying for not less than five days marks made on the painted 
 surface with a soft lead pencil-(No. 2 Mogul) shall be easily re- 
 moved by washing with soap, and. warm water without appre- 
 ciably marring the paint surface. The weight per gallon shall be 
 not less than 124 pounds. The paint shall consist of: 
 
 _- 
 2 
 
 Deliveries will, im esa: be pride: wee phe we ew the jollowing 
 methods, but the purchaser reserves the right to use any additional 
 available. information to ascertain whether. the. Cte He meets the 
 specification. >» bre .totew Bi 
 
 2. SAMPLING. ; 
 
 It is mutually agreed by buyer and seller that a cine beds snd 
 out of each lot of not more than 1,000 packages shall be taken, as 
 representative of the whole. Whenever possible, an original 
 
Specification jor Gloss Intervor Lithopone Paint. 3 
 
 unopened container shall be sent to the laboratory, and when this 
 is for any reason not done the inspector shall determine by thorough 
 testing with a paddle or spatula whether the material meets the 
 requirement regarding caking in the container. He shall then 
 thoroughly mix the contents of the container and draw a sample 
 of not less than 5 pounds. This sample shall be placed in a clean, 
 dry metal or glass container, which it must nearly fill. The con- 
 tainer shall be closed with a tight cover, sealed, marked, and sent 
 to the laboratory for test with the inspector’s report on caking. 
 
 When requested, a duplicate sample may be taken from the 
 same package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 3. LABORATORY EXAMINATION. 
 
 © (a) Caxinc In CONTAINER.—When an original package is 
 received in the laboratory, it shall be weighed, opened, and 
 stirred with a stiff spatula or paddle. The paint must be no more 
 difficult to mix to a uniform consistency than a good grade of 
 gloss mill white. The paint shall finally be thoroughly mixed, 
 removed from the container, and the container wiped clean and 
 weighed. This weight subtracted from the weight of the original 
 package gives the net weight of the contents. A portion of the 
 thoroughly mixed paint shall be placed in a clean container and 
 portions for the remaining tests promptly weighed out. 
 
 (b) Coyor.—Place some of the paint on a clean, clear glass 
 plate. Place some of the standard agreed upon beside the sample 
 on the plate, turn the glass over, and compare the colors. 
 
 (c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc grad- 
 uated flask. Fill to the mark with the thoroughly mixed paint 
 and weigh again. The increase in weight expressed in grams, 
 divided by 100, gives the specific gravity, which, multiplied by 
 
 8.33, gives the weight in pounds per gallon. 
 
 -. (d) BRUSHING PROPERTIES, TrmE OF DRYING, AND RESISTANCE 
 to WasHING.—Brush the well-mixed paint on a suitable panel, 
 “which may be ground glass, steel, or well-filled wood. Note 
 whether the paint works satisfactorily under the brush. Place 
 the panel in a vertical position in a well-ventilated room and let 
 it stand for 24 hours. The paint should be dry and free from 
 ‘streaks. Let the panel stand for five days, then make marks on 
 it with a soft lead pencil (No. 2 Mogul) and wash these marks off 
 with warm (75° C.) distilled water and white floating soap, using 
 
4 Circular of the Bureau of Standards. 
 
 a sponge or soft rag. The marks must be removed: by, this treat- 
 ment without appreciably marring the paint film. } 
 
 Flow a portion of the paint on a clean glass plate. Let dry ina 
 nearly vertical position at room temperature (65 to 100° F.). The 
 film shall show no streaking or separation within a distance of 
 4 inches from the top. tte 
 
 (ec) Fastness to Licnr.—Apply a sufficient number of. coats 
 of the paint to a ground-glass plate to completely hide the, sur- 
 face, cover half of this painted surface with opaque black paper, 
 and expose indoors in a well-lighted room for five days., Remove 
 the black paper and examine the surface. The exposed portion 
 should be no darker than the portion protected by the black 
 paper. 
 
 (f) YELLowinc.—Apply a sufficient number of coats of the 
 paint to two ground-glass plates to completely hide the surface; 
 after applying the last coat let dry in a well-lighted room for 
 five days. Place one of the plates in a dark room or cabinet * 
 with a warm, very humid atmosphere, for 96 hours. Remove 
 from cabinet and compare with the plate that has been kept in. 
 a light room. The plate kept in the dark shall be only slightly 
 yellower than the plate kept in the light. There shall be no 
 greater difference in color of the two plates than there will be 
 with similar plates coated with the best grade of paint of this 
 general nature. 
 
 (g) WatTER.—Mix 100 g of the paint in a 300 ce flask wits 75 
 ce of toluol. Connect with a condenser and distil until about 50 
 ce of distillate has been collected in a graduate The temperature 
 in the flask should be then about 105 to 110° C. The number of 
 cubic centimeters of water collecting under the toluol in she 
 receiver is the percentage of water in the paint. 
 
 (hk) VOLATILE THINNER.—Weigh accurately from 3 to 5 2 
 of the paint into a tared flat-bottomed dish about 8 cm,in diam- 
 eter, spreading the paint over the bottom. Heat at 105 to 110° 
 C. for three hours, cool, and weigh. Calculate the loss in weight as 
 percentage of water and volatile thinner, subtract from, this the 
 percentage of water (3, 9); and report the remainder as volatile 
 thinner. 
 
 (1) PERCENTAGE OF PIGMENT.—Weigh acquit Smal I 5 g 
 of the paint into a weighed centrifuge tube. Add .20 to 30 cc 
 of ‘‘extraction mixture” (see Reagents), mix thoroughly with a 
 
 1A convenient cabinet for this test is described in Circular No. 152, Hducational! Bureau, Scientific 
 Section, Paint Manufacturers’ Association of the United States. 
 
Specification for Gloss Interior Lithopone Pant. 5 
 glass rod, wash the rod with more of the extraction mixture, and 
 add sufficient of the reagent to make a total of 60 cc in the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm with 
 a similar tube or a tube with water. Whirl at a moderate speed 
 until well settled. Decant the clear supernatant liquid. Repeat 
 the extraction twice with 40 cc of extraction mixture and once 
 with 4o ce of ether. After drawing off the ether set the tube in a 
 beaker of water at about 80° C. or on top of a warm oven for 10 
 minutes, then in an oven at 105 to 110° C. for two hours. Cool, 
 weigh, and calculate the percentage of pigment. Grind the pig- 
 ment to a fine powder, pass through a No. 80 sieve to remove any 
 skins, and preserve in a stoppered bottle. Preserve the extracted 
 vehicle for 3 (k). 
 
 (7) PERCENTAGE OF NONVOLATILE VEHICLE.—Add. together 
 the percentages of water (3, g), of volatile thinner (3, 2), and of 
 pigment (3, 7), and subtract the sum from roo. The remainder 
 is the percentage of nonvolatile vehicle. 
 
 (k) NaTuRE oF NONVOLATILE VEHICLE.—Evaporate the ex- 
 tracted vehicle and extraction mixture from 3 (2) to about 5 cc. 
 Thoroughly clean with benzol a piece of bright sheet iron, tin 
 plate, or terneplate. Spread a portion of the concentrated 
 extracted vehicle on the sheet of metal, allow to dry for 30 minutes 
 at room temperature in a vertical position, bake for three hours 
 at 100 to 110° C. (212 to 221° F.), remove from the oven, and keep 
 at room temperature for three days. Place the panel with the 
 coated side uppermost over a 3 mm (14-inch) rod, held firmly by 
 suitable supports, at a point equally distant from the top and 
 bottom edges of the panel and bend double rapidly. The dried 
 vehicle must show no cracking whatever at the point of bending. 
 Test the film with a knife blade at a place not less than 2.5 cm 
 (t inch) from the edge. The film should be tough and elastic. 
 If it powders, or if particles fly under the test, it will be considered 
 brittle, which will be cause for rejection. The film must also 
 stand light, vigorous rubbing with the finger without powdering 
 or disintegrating. 
 
 (1) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
 110° C. a No. 325 sieve, cool, and weigh accurately: Weigh an 
 ‘amount of paint containing 10 g of pigment (see 3, 7), add 50 cc 
 of kerosene, mix thoroughly, and wash with kerosene through 
 the sieve, breaking up all lumps, but not grinding.. After washing 
 
6 Circular of the Bureau of Standards. 
 
 with kerosene until all but the particles too coarse to pass the sieve 
 have been washed through wash all kerosene from the sieve with 
 ether or petroleum ether, heat the sieve for one hour at 105 to 
 110° C., cool, and weigh. 
 
 4. ANALYSIS OF PIGMENT. 
 
 Use the pigment extracted in 3 (7). 
 
 (a) QUALITATIVE ANALYsIS.—Make qualitative analysis, fol- 
 lowing ordinary methods. 
 
 (6) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
 ment to a graduated 250 cc flask, add 100 cc of water, boil for five 
 minutes, cool, fill to mark with water, mix, and allow to settle. 
 Pour the supernatant liquid through a dry filter paper and dis- 
 card the first 20 cc. Then evaporate 100 cc of the clear filtrate 
 to dryness in a weighed dish, heat for one hour at 105 to 110° C., © 
 cool, and weigh. 1 | 
 
 (c) BARIUM SULPHATE AND SILICEOUS MATERIAL.—Transfer 1 
 g of pigment to a porcelain casserole or dish, moisten with a few 
 drops of alcohol, add 40 cc of hydrochloric acid (1.1 specific 
 gravity), cover, and boil to expel hydrogen sulphide. Remove the 
 cover and evaporate to dryness on the steam bath, moisten with 
 hydrochloric acid, dilute with water, filter through paper, and 
 wash with dilute hydrochloric acid and then with hot water until 
 the washings are free from zinc and chlorine. Ignite and weigh 
 the residue, which will be barium sulphate and siliceous material. 
 
 Mix the ignited residue with about 10 times its weight of anhy- 
 drous sodium carbonate (grind the mixture in an agate mortar, if 
 necessary), fuse the mixture in a covered platinum crucible, 
 heating about one hour. Let cool, place the crucible and cover in 
 a 250 cc beaker, add about 100 cc of water, and heat until the melt 
 is disintegrated. Filter on paper (leaving the crucible and cover 
 in the beaker) and wash the beaker and filter thoroughly with 
 hot water to remove soluble sulphates. Place the beaker con- 
 taining the crucible and cover under the funnel, pierce the filter 
 with glass rod, and wash the carbonate residue into the beaker 
 by means of a jet of hot water. Wash the paper with hot, dilute 
 hydrochloric acid (1:1) and then with hot water. If the car- 
 bonate residue is not completely dissolved, add sufficient dilute 
 -hydrochloric acid to effect solution and remove the crucible and 
 cover, washing them with a jet of water. Heat the solution to 
 boiling and add 10 to 15 cc of dilute sulphuric acid and continue 
 the boiling for 10 or 15 minutes longer. Let the precipitate 
 
a ee ae 
 
 4 
 : 
 j 
 3 
 4 
 
 Specification jor Gloss Interior Lithopone Patnt. 7 
 
 settle, filter on a weighed Gooch crucible, wash with hot water, 
 ignite, cool, and weigh as BaSO,. Subtract from the result of the 
 previous determination to obtain the siliceous material. 
 
 (d) Tora, ZINC CALCULATED AS ZINC OxIDE.—With material 
 containing no interfering elements (iron, for example) weigh 
 accurately about 1 g of pigment, transfer to a 400 cc beaker, 
 
 ‘moisten with alcohol, add 30 cc of hydrochloric acid (1:2), boil 
 
 for two to three minutes, add 200 cc of water and a small piece of 
 litmus paper; add strong ammonia until slightly alkaline, render 
 just acid with hydrochloric acid, then add 3 cc of strong hydro- 
 chloric acid, heat nearly to boiling, and titrate with standard 
 ferrocyanide as in standardizing that solution (see Reagents). 
 Calculate total zinc as zinc oxide. 
 
 When iron or other interfering elements are present (see 4, a), 
 take the filtrate containing the zinc from 4 (c), add a slight excess 
 of bromine water and 2 g of ammonium chloride, heat to nearly 
 boiling, add an excess of ammonia, heat for about two minutes, 
 filter, dissolve the precipitate in hydrochloric acid, add 2 g of 
 ammonium, chloride, and reprecipitate with ammonia as above. 
 Filter, wash the precipitate with hot 2 per cent, ammonium- 
 chloride solution, unite the two filtrates, and determine zinc as 
 
 above... | 
 
 — (e) Zinc OxipE.— Weigh accurately 2.5 g of pigment, transfer 
 to.a 250 cc graduated flask, moisten with a few drops of alcohol, 
 add about 200 cc of 1 to.3 per cent acetic acid, shake vigorously, 
 and let stand for 30 minutes, shaking once very five minutes. Fill 
 to the mark with 1 to 3 per cent acetic acid, mix, filter through a 
 dry paper, discard the first 25 cc, and determine zinc in 100 cc of 
 the filtrate (corresponding to 1 g) as in 4 (d).. Calculate the 
 percentage of zinc oxide. : 
 
 ~ (f) CaLcuLations.—Subtract the percentage of zinc oxide (4, 
 e) from the percentage of total zinc as zinc oxide (4, d) and multi- 
 ply the remainder by 1.2 to convert to percentage of zinc sulphide. 
 In case the percentage of barium sulphate (4, c) is not more than 
 2.86 times as great as the percentage of zinc sulphide, add the two 
 together and call the sum the percentage of lithopone. If the 
 percentage of barium sulphate is greater than this amount, take 
 2.86 times the percentage of zinc sulphide as the percentage of 
 barium sulphate to ‘be included in the percentage of lithopone and 
 include the remainder in the percentage of tinting and extending 
 pigments. Subtract the sum of the percentages of zinc oxide 
 
8 Circular of the Bureau of Standards. 
 
 (4, e), lithopone, and matter soluble in water (4, b)from 100. Call 
 the remainder percentage of tinting and extending pigments. 
 
 5. REAGENTS. 
 
 (a) EXTRACTION MrxTuRE.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 4 volumes methyl alcohol. 
 I volume acetone. 
 
 (b) ONE To THREE PER Cent Acetic Actp.—Dilute 20 ce os 
 glacial acetic acid to 1,000 ce with distilled water. 
 
 (c) UrRaNyL INDICATOR FOR ZINC TITRATION.—A 5 per cent 
 solution of uranyl nitrate in water or a 5 per cent solution of 
 uranyl acetate in water made slightly acid with acetic acid. 
 
 (d) STANDARD PoTassIUM FERROCYANIDE.—Dissolve 22 g of the 
 pure salt in water and dilute to 1,000 cc. To standardize, transfer 
 about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
 ignited pure zinc oxide to a 400 ce beaker. Dissolve in ro cc of 
 hydrochloric acid and 20ccofwater. Dropinasmall pieceoflitmus 
 paper, add ammonium hydroxide until slightly alkaline, then add 
 hydrochloric acid until just acid, and then 3 cc of strong hydro-. 
 chloric acid. Dilute to about 250 ce with hot water and heat 
 nearly to boiling. Run in the ferrocyanide solution slowly from a 
 burette, with constant stirring until a drop tested on a white 
 porcelain plate with a drop of the uranyl indicator shows a brown 
 tinge after standing one minute. A blank should be run with the 
 same amounts of reagents and water as in the standardization. 
 The amount of ferrocyanide solution required for the blank should 
 be subtracted from the amount used in standardization and in 
 titration of the sample. The standardization must be made 
 under the same conditions of temperature, volume, and acidity as 
 obtain when the sample is titrated. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. ¢C. 
 AT 
 5 CENTS PER COPY 
 PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
 COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY II, 1922 
 
 Vv 
 
mb ® DH H 
 
 U.S. Gov’t 
 Standard 
 Specification, 
 
 No. 115. 
 
 DEPARTMENT OF COMMERCE. 
 BUREAU OF STANDARDS. 
 
 George EK. Burgess, Director. 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 163. 
 [February 20, 1924.] 
 
 UNITED STATES GOVERNMENT SPECIFICATION FOR 
 TITANIUM PIGMENT, DRY AND PASTE. . 
 
 FEDERAL SPECIFICATIONS BOARD. 
 STANDARD SPECIFICATION No. 115. 
 
 This specificatio:. was officially adopted by the Federal Specifications Board 
 on February 20, 1924, for the use of the Departments and Independent Estab- 
 lishments of the Government in the purchase of titanium pigment, dry and paste. 
 
 CONTENTS. 
 
 Page. 
 
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 1. GENERAL. 
 
 Titanium pigment may be ordered in the form of dry pigment or 
 paste ground in linseed oil. The material shall be purchased by 
 net weight. | 
 
 (a) Dry Picment.—The pigment shall be 25 per cent titantum 
 oxide precipitated upon and coalesced with 75 per cent of blanc 
 fixe (precipitated barium sulphate). It shall be thoroughly 
 
 - washed, shall be free from adulterants, and shall meet the fol- 
 
 lowing requirements. 
 
 Color—Color strength—When specified, the color and color 
 strength shall be equal to that of a sample mutually agreed upon . 
 by buyer and seller. 
 
 84628°—24 
 e 
 
2 | Circular of the Bureau of Standards 
 
 — 
 
 Mini- | Mazi- 
 mum. mum, 
 
 Per cent. | Per cent. 
 Coarse particles retained on No. 325 sieve... .25.ic: des bi dese ocncc cde cevesendegedell ce 1.0 
 Titanium oxide ee ii bisigs 00002 Peeves rE es re 
 
 (6) Paste.—The ‘paste shall be made by thoroughly grinding 
 the above-described pigment with pure, raw, or refined linseed oil. 
 
 The paste as received shall not be caked in the container and 
 shall break up readily in oil to form a smooth paint of ead 
 consistency. The paste shall consist of: 
 
 Cem MEER Oe DCB HRM ERE Be HAE meer er eases ESewrssescusisanseuseace 
 
 Care particles and “‘ skins ” (total residue retained on No. 325 sieve, based on pig- a. 
 THONG)... 222 c ces ns cine vnuinisien sieis eu pie Saleen 5:c.b balan w o\ajalen bls ol line ia innit aes a . 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available tnjormaiion to asceriain whether the. material meets the 
 specification. 
 
 2. SAMPLING. 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages be taken as repre- 
 sentative of the whole. 
 
 (a) Dry Prcment.—The package is to be opened by the 
 inspector and a sample of not less than 5 pounds taken at random 
 from the contents and sent to the laboratory for test. 
 
 (6) PastE.—Whenever possible, an original unopened con- 
 tainer shall be sent to the laboratory; and when this is for any 
 reason not done the inspector shall determine by thoroughly 
 testing with a paddle or spatula whether the material meets the 
 requirement regarding not caking in the container. (See 4 (a).) 
 After assuring himself that the paste is not caked in the can, the 
 
 inspector shall draw a sample of not less than 5 pounds of the ~ 
 
 thoroughly mixed paste, place it in a clean, dry metal or glass 
 container, which must be filled with the sample, closed with a 
 tight cover, sealed, marked, and sent to the laboratory for test 
 with the inspector’s report on caking in container. 
 
Specificaiion for Titamum Pigment 3 
 
 When requested, a duplicate sample may be taken from the 
 same package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 3. LABORATORY EXAMINATION, DRY PIGMENT. 
 
 (a) CoLor.—Take 5 g of the sample, add 1.5 cc of linseed oil, 
 rub up on a stone slab or glass plate with a flat-bottomed glass or 
 stone pestle or muller to a uniform smooth paste. Treat in a simi- 
 lar manner 5 ¢ of the standard titanium pigment. Spread the 
 two pastes side by side on a clear, colorless glass plate and compare 
 the colors. If the sample is as white as or whiter than the “ stand- 
 ard,’’ it passes this test. If the ‘‘standard” is whiter than the 
 sample, the material does not meet the specification. 
 
 (6) CoLOR STRENGTH.—Weigh accurately o.o1 g of lamp- 
 black, place on a large glass plate or stone slab, add 0.2 cc of lin- 
 seed oil and rub up with a flat-bottomed glass pestle or muller, 
 then add exactly 10 g of the sample and 2.5 cc of linseed oil, and 
 grind with a circular motion of the muller 50 times; gather up 
 with a sharp-edged spatula and grind out twice more in a like 
 manner, giving the pestle a uniform pressure. Treat another 
 0.01 g of lampblack in the same manner, except that 10 g of stand- 
 ard titanium pigment is used instead of 10g of the sample. Spread 
 the two pastes side by side on a glass microscope slide and com- 
 pare the colors. If the sample is as light as or lighter in color 
 than the “standard,” it passes this test. If the “standard” is 
 lighter in color than the sample, the material does not meet the 
 specification. 
 
 (c) COARSE PartricLes.1—Dry in an oven at 105 to 110° C. a 
 No. 325 sieve, cool, and weigh accurately. Weigh 10 g of the 
 sample, wash with water through the sieve, breaking up all lumps 
 either by gentle pressure with a pestle in a mortar, but not grind- 
 ing, or with a brush on the sieve.. After washing with water until 
 all but the particles too coarse to pass the sieve have been washed 
 through, dry the sieve for one hour at 105 to 110° C., cool, and 
 weigh. 
 
 (d) QUALITATIVE ANALYSIS.—Place a small amount (about one- 
 half gram) of the sample in a 250 cc Pyrex glass beaker; add 20 
 ec of concentrated sulphuric acid and 7 to 8 g of ammonium sul- 
 phate. Mix well, and boil fora few minutes. The sample should 
 
 1 For a general discussion of sieve tests of pigments and data regarding many pigments on the market see 
 Circular No. 148 of the Educational Bureau, scientific section, Paint Manufacturers’ Association of the 
 United States. 
 
4 Circular of the Bureau of Standards. 
 
 go completely into solution; a residue denotes the presence of 
 Silica or siliceous matter. Cool the solution, dilute with 100 cc 
 of water, heat to boiling, settle, filter, wash with hot 5 per cent 
 sulphuric acid until free from titanium, and test the residue for 
 lead, etc. Test the filtrate for calcium, zinc, iron, chromium, etc., 
 by regular methods of qualitative analysis. For the iron deter- 
 mination take a portion of the filtrate, add 5 g of tartaric acid, 
 make slightly ammoniacal, pass in hydrogen sulphide in excess, 
 and digest at the side of a steam bath for a while. No precipitate 
 denotes absence of iron, nickel, cobalt, lead, copper, ete. A 
 black precipitate easily soluble in dilute hydrochlo-ic acid denotes 
 iron. For titanium test a small portion of the original filtrate 
 with hydrogen peroxide (a clear yellow-orange color should result) 
 and another portion with metallic tin or zinc (a pale blue to violet 
 coloration should result). 
 
 The pigment should show negative tests for sulphide sulphur, 
 carbonates, and appreciable water-soluble matter. 
 
 (ec) MorsturRE.—Place 1 g of the sample in a wide-mouth, short 
 weighing tube provided with a glass stopper. Heat with the stop- 
 per removed for two hours at a temperature between 105 and 110° 
 C. Insert the stopper, cool, and weigh. Calculate the loss in 
 weight as moisture. 
 
 (f) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pigment 
 to a graduated 250 cc flask, add 100 cc of water, boil for five 
 minutes, cool, fill to the mark with water, mix, and allow to 
 settle. Pour the supernatant liquid through a dry filter paper 
 and discard the first 20 cc. Then evaporate 100 cc of the clear 
 filtrate to dryness in a weighed dish, heat for one hour at 105 to 110° 
 ~ ¢., cool, and weigh. 
 
 ti) TITANIUM OXIDE. 
 250 cc Pyrex beaker, add 20 cc of concentrated sulphuric acid 
 and 7 to 8 g of ammonium sulphate. Mix well and heat on a hot 
 plate until fumes of sulphuric acid are evolved, and then con- 
 tinue the heating over a strong flame until solution is complete 
 (usually not over five minutes of boiling) or it is apparent that the 
 residue is composed of silica or siliceous matter. Caution should 
 be observed in visually examining this hot solution. Cool the 
 solution, dilute with 100 ce of water, stir, heat carefully to boiling 
 while stirring, settle, filter through paper and transfer the precipi- 
 tate completely to the paper. Wash the insoluble residue with 
 cold 5 per cent (by volume) sulphuric acid until titanium is 
 removed. 
 
Specification for Titanrwm Pigment. 5 
 
 Dilute the filtrate to 200 cc and add about 10 ce of ammonia, 
 specific gravity 0.90, to lower the acidity to approximately 5 
 per cent sulphuric acid (by volume). 
 
 Wash out a Jones reductor ? with dilute 5 per cent (by volume) 
 sulphuric acid and water, leaving sufficient water in the reductor 
 to fill to the upper level of the zinc. (These washings should 
 require not more than one or two drops of 0.1 N potassium per- 
 manganate solution to obtain the pink color.) Empty the 
 receiver, and put in it 25 cc (measured in a graduate) of ferric 
 sulphate solution. (See Reagents.) Reduce the prepared tita- 
 nium solution as follows: (1) Run socc of the 5 per cent sulphuric 
 acid solution through the reductor at a speed of about 100 cc 
 per minute; (2) follow this with the titanium solution; (3) wash 
 out with roo ce of 5 per cent sulphuric acid; (4) finally run through 
 about 100 cc of water. 
 
 Care should be observed that the reductor is always filled with 
 solution or water to the upper level of the zinc. 
 
 Gradually release the suction, wash thoroughly the glass tube 
 that was immersed in the ferric sulphate solution, remove the’ 
 receiver, and titrate immediately with o.1 N potassium ESHAaA 
 ganate solution. (See Reagents.) 
 
 1 cc 0.1 N KMnO,=0.00481 g Ti 
 =0.00801 g TiO, 
 
 Run a blank determination, using the same reagents, washing 
 the reductor as in the above determination. Subtract this per- 
 manganate reading from the original reading and calculate the 
 final reading to titanium dioxide (TiO,) (which will include iron, 
 chromium, arsenic, and any other substance which is reduced by 
 zine and acid). (See 3 (2) for reporting TiO,.) ® 
 
 (h) DETERMINATION OF BARIUM SULPHATE.—Ignite and weigh 
 the precipitate of BaSO, obtained in separating the titanium.‘ 
 (See 3 (g).) 
 
 (4) IRON OxIpDE.—Prepare a standard ferric solution contain- 
 ing o.oooo1 g Fe per cc. (See Reagents.) Weigh a1 g portion 
 of the sample and treat as in 3 (g), transfer without filtering to a 
 200 cc flask, cool, fill to the mark, and determine iron colorimetri- 
 cally in 50 ce aliquots in the following manner. Filter through a 
 
 3 Directions for preparing a Jones reductor may be found in Blair, *‘ The Chemical Analysis of Iron,” 
 8th ed. Lippincott & Co., or Tread well-Hall, “Analytical Chemistry 2,”’ sth ed. J. Wiley & Sons, p. 638 
 8 Any other accurate method of determining titanium oxide may be used. For a discussion of various 
 methods see ‘‘The Analysis of Silicate and Carbonate Rocks,” by W. F. Hillebrand, U. S. Geological 
 Survey Bulletin 7co. 
 4 Jf the sample is impure it may be necessary to purify this precipitate, using appropriate methods. 
 84628°—24 2 
 
6 Circular of the Bureau of Standards 
 
 dry filter paper (discarding the first 20 cc), and transfer 50 ce 
 of the filtrate to a clean 100 ce Nessler tube or other color com- 
 parator. Add a drop or two of 0.1 N KMn0O, solution, to oxidize 
 any ferrous iron until a faint pink color is obtained. Add 10 ce 
 of ammonium or potassium thiocyanate solution (see Reagents), 
 dilute to 100 cc, and mix thoroughly. Compare the color imme- 
 diately with a series of standards, prepared side by side with the 
 sample in similar tubes. 
 
 Prepare the standards from the standard ferric solution so as 
 to have a range of from 0.000005 g Fe to 0.00004 g (0.5 to 4.0 cc). 
 Transfer the desired volumes of the standard dilute ferric solution 
 to 100 ce Nessler tubes containing 50 ce each of an acid solution 
 (made by dissolving 8 g of (NH,), SO, in water, adding 20 ce of 
 concentrated H,SO,, cooling, diluting with water to 200 ce and 
 mixing), add a drop of 0.1 N KMnO, solution (or sufficient to 
 yield a pink color that will persist for 5 minutes), and then 10 cc 
 of the thiocyanate solution. Finally dilute all standards with 
 water to 100 ce and mix thoroughly. iy 
 
 For a single sample it is more convenient to run the standard Fe solution from a 
 burette into a Nessler tube containing 50 cc of the acid solution, a drop of 0.1 N KMnO, 
 solution, and 10 cc of the thiocyanate solution, until on diluting to roo ce with dis- 
 tilled water and mixing, the color exactly matches that of the sample. From the 
 burette reading calculate the amount of Fe. The color comparisons must be made 
 immediately after the standards are prepared. 
 
 Calculate the total iron found to Fe,O, and report as such. 
 Calculate the TiO, equivalent by multiplying by the factor 1.003 
 and subtract this figure from the total titanium oxide as deter- 
 mined in 3 (g) and report the remainder as ‘TiO,. 
 
 4. LABORATORY EXAMINATION, PASTE. 
 
 (a) CAKING IN CONTAINER.—When an original package is re- 
 ceived in the laboratory it shall be weighed, opened, and stirred 
 with a stiff spatula or paddle. The paste must be no more diffi- 
 cult to break up and show no more caking than a normal good 
 grade of titanium pigment paste. The paste shall finally be 
 thoroughly mixed, removed from the container, the container 
 wiped clean, and weighed. This weight subtracted from the 
 weight of the original package gives the net weight of the con- 
 tents. A portion of the thoroughly mixed paste shall be placed 
 in a clean container, and the portions for the remaining tests. 
 promptly weighed out. 
 
 (6) MIXING WITH LINSEED O1L.—One hundred grams of the paste 
 shall be placed in a cup, 40 ce of linseed oil added slowly with 
 
p- ee ee A ee eee be 
 
 Specification for Tritaniwm Pigment. 7 
 
 careful stirring and mixing with a spatula or paddle. The re- 
 sulting mixture must be smooth and of good brushing consistency. 
 Flow a portion of this paint on a clean glass plate. Let stand in 
 a nearly vertical position at room temperature (65 to 100° F.). 
 The film after four hours shall show no streaking or ean, 
 within a distance of 4 inches from the top. 
 
 (c) MoIstTURE AND OTHER VOLATILE MATTER.—Weigh tiaeiy 
 from 3 to 5 g of the paste into a tared flat-bottomed dish, about 
 8 cm in diameter, spreading the paste over the bottom. Heat at 
 105 to 110° C. for three hours, cool, and weigh. Calculate the loss 
 in weight as the percentage of moisture and other volatile matter. 
 
 (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
 of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
 of ‘extraction mixture’’ (see Reagents), mix thoroughly with a 
 glass rod, wash the rod with more of the extraction mixture, and 
 add sufficient of the reagent to make a total of 60 cc im the tube. 
 Place the tube in the container of a centrifuge, surround with 
 water, and counterbalance the container of the opposite arm with 
 a similar tube or a tube with water. Whirl at a moderate speed 
 until clear. Decant the clear supernatant liquid. Repeat the 
 extraction twice with 40 cc portions of extraction mixture, and once 
 with 40 cc of ether. After drawing off the ether, set the tube in a 
 beaker of water at about 80° C. or on top of a warm oven for 10 
 minutes, then in an oven at 105 to 110° C. for two hours. Cool, 
 weigh, and calculate the percentage of pigment. 
 
 (ec) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
 to a fine powder, pass through a No. 80 sieve to remove any 
 ‘skins,’ and preserve in a stoppered tube and apply tests 3 (d), 
 (f), (g), (A), and (2). If required, apply tests 3 (a) and (0) in 
 comparison with a portion of pigment extracted from the standard 
 paste in exactly the same manner as in extracting the sample. 
 
 (f) PREPARATION oF Farry Acips.—To about 25 g of the paste 
 in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
 (see Reagents), and 75 cc of ethyl alcohol, mix and heat uncovered 
 on a steam bath until saponification is complete (about one hour). 
 Add 100 cc of water, boil, add sulphuric acid of specific gravity 
 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
 funnel to which some water has been previously added. Draw 
 off as much as possible of the acid aqueous layer, wash once with 
 water, then add 50 ce of water and 50 cc of ether. Shake very 
 gently with a whirling motion to dissolve the fatty acids in the 
 ether, but not violently, so as to avoid forming an emulsion. 
 Draw off the aqueous layer and wash the ether layer with one 15 
 
8 Circular of the Bureau of Standards. 
 
 ce portion of water and then with 5 ce portions of water until free 
 from sulphuric acid. ‘Then draw off completely the water layer. 
 Transfer the ether solution to a dry flask, and add 25 to 50 g of 
 anhydrous sodium sulphate. Stopper the flask and let stand with 
 occasional skaking at a temperature below 25° C. until the water 
 is completely removed from the ether solution, which will be 
 shown by the solution becoming perfectly clear above the solid 
 sodium sulphate. Decant this clear solution (if necessary through 
 a dry filter paper) into a dry 100 cc Erlenmeyer flask. Pass a 
 rapid current of dry air (pass through a CaCl, tower) into the 
 mouth of the Erlenmeyer flask and heat to a temperature below 
 75°C. ona dry hot plate until the ether is entirely driven off. 
 
 It 1s wmportant to follow all of the details, since ether generally 
 contains alcohol, and after washing with water always coniains 
 water. It is very difficult to remove water and alcohol from fatty 
 acids by evaporation, but the washing of the ether solution and sub- 
 sequent drying with anhydrous sodium sulphate removes both water 
 and alcohol. Ether, wm the absence of water and alcohol, 1s easily 
 removed from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (g) TEST FOR MINERAL OIL, AND OTHER UNSAPONIFIABLE MAT- 
 TER.—Place 1o drops of the fatty acid (f) ina 50 cc test tube, add 
 5 ce of alcoholic soda (see Reagents), boil vigorously for five min- 
 utes, add 4o cc of water, and mix; a clear solution indicates that 
 ~not more than traces of unsaponifiable matter are present. If 
 the solution is not clear, the oil is not pure linseed oil. 
 
 (h) lopINE NUMBER OF Farry Acrps.—Place a small quantity 
 of the fatty acids (f) in a small weighing burette or beaker. 
 Weigh accurately. Transfer (by dropping) about 0.15 ¢g (0.10 to 
 0.20 g) to a 500 cc bottle having a well-ground glass stopper, or 
 an Erlenmeyer flask having a specially flanged neck for the iodine 
 test. Reweigh the burette or beaker and determine the amount 
 of sample used. Add 10 ce of chloroform. Whirl the bottle to 
 dissolve the sample. Add 10 cc of chloroform to two empty 
 bottles like that used for the sample. Add to each bottle 25 cc of 
 the Hanus solution (see Reagents) and let stand, with occasional 
 shaking, for one-half hour. Add 10 cc of the 15 per cent potas- 
 siusm-iodide solution and 100 cc of water, and titrate with standard 
 sodium thiosulphate, using starch as indicator. The titrations on 
 the two blank tests should agree within 0.1 cc. From the iodine 
 value of the thiosulphate solution and the difference between the 
 
@ ae Se eee ee eee ee ae ee 
 
 — a a oe oP re 
 
 Specification for Titanium Pigment. 9 
 
 average of the blank titrations and the titration on the sample, 
 calculate the iodine number of the sample tested. (Iodine number 
 is centigrams of iodine to 1 g of sample.) If the iodine number is 
 less than 170, the oil does not meet the specification. 
 
 (1) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
 110° C. a No. 325 sieve. Weigh an amount of paste containing 
 10 g of pigment (see 4 (d)), add 100 cc of kerosene, mix thoroughly, 
 and wash with kerosene through the sieve, breaking up all lumps but 
 not grinding. After washing with kerosene until all but particles 
 too coarse to pass the sieve have been washed through, wash all 
 kerosene from the sieve with ether or petroleum ether, heat the 
 sieve for one hour at 105 to 110° C., cool, and weigh. 
 
 5. REAGENTS. 
 
 (a) ExTRACTION MIxTURE.— 
 10 volumes ether (ethyl ether). 
 
 6 volumes benzol. 
 
 4 volumes methyl alcohol. 
 
 I volume acetone. 
 (b) Aguzous Sopium Hyproxipe.—Dissolve 100 g sodium 
 
 hydroxide in distilled water and dilute to 300 cc. 
 
 (c) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve pure 
 
 sodium thiosulphate in distilled water that has been well boiled to 
 
 free it from carbon dioxide, in the proportion of 24.83 g of crys- 
 tallized sodium thiosulphate to 1,000 ce of the solution. It is. 
 best to let this solution stand for about two weeks before standard- 
 izing. Standardize with pure resublimed iodine.’ This solution 
 will be approximately decinormal, and it is best to leave it as it is 
 after determining its exact iodine value rather than to attempt to 
 adjust it to exactly decinormal. Preserve in a stock bottle pro- 
 vided with a guard tube filled with soda lime. 
 
 (d) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 
 g of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
 add 300 to 400 cc of boiling water, and boil the mixture until the 
 starch is practically dissolved, then dilute to 1 liter. 
 
 (ec) Porassrum IopipE SoLuTION.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water, and dilute to 1,000 cc. 
 
 ({f) Hanus SOLUTION.—Dissolve 13.2 g of iodine in 1,000 cc 
 of 99.5 per cent glacial acetic acid which will not reduce chromic 
 acid. Add enough bromine to double the halogen content, 
 determined by titration (3 cc of bromine is about the proper 
 
 ’ Tread well-Hall, Analytical Chemistry, 2, sth ed., p. 645. 
 
fe) Circular of the Bureau of Standards. 
 
 amount). The iodine may be dissolved by the aid of heat, but 
 the solution should be cold when the bromine is added. 
 
 (g) ALCOHOLIC SopruM HyprROxIDE SOLUTION:—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 about 22 g per 1,000 cc. Let stand in a stoppered bottle. De- 
 cant the clear liquid into another bottle and keep well stoppered. 
 This solution should be colorless or only slightly yellow when 
 used, and it will keep colorless longer if the alcohol is previously 
 treated with sodium hydroxide (about 80 g to 1,000 ec), kept at 
 about 50° C. for 15 days and then distilled. 
 
 (h) o.1 N Porasstum PERMANGANATE SOLUTION. Dissolve 
 3.161 g of pure potassium permanganate in a liter of distilled 
 water, let stand 8 to 14 days, siphon off the clear solution (or 
 filter through an asbestos filter), and standardize as follows: In 
 a 400 cc beaker dissolve 0.25 to 0.30 g of Bureau of Standards’ 
 sodium oxalate in 250 cc of hot water (80 to go° C.) and add 15 
 ce of dilute sulphuric acid (1:1). ‘Tiitrate at once with the potas- 
 sium permanganate solution, stirring the lqgmd vigorously and 
 continuously. The permanganate must not be added more 
 rapidly than ro to 15 cc per minute, and the last 0.5 to 1 ce must 
 be added dropwise with particular care to allow each drop to be 
 fully decolorized before the next is introduced. ‘The solution 
 should not be below 60° C. by the time the end point is reached. . 
 (More rapid cooling may be prevented by allowing the beaker to 
 stand on a small asbestos-covered hot plate during the titration. 
 The use of a small thermometer as a stirring rod is most convenient.) 
 The weight of sodium oxalate used multiplied by 0.8334 gives its 
 iron equivalent, or multiplied by 1.1954 gives its titanium dioxide 
 (TiO,) equivalent*. The permanganate solution should be kept 
 in a glass-stoppered bottle painted black to keep out light. 
 
 (t) FERRIC SULPHATE SOLUTION For TrtTanruM.—A solution 
 containing 2 per cent of iron as ferric sulphate is desired and may 
 be prepared as follows: , Dissolve 20 g of pure iron or plain carbon 
 steel in a slight excess of hydrochloric acid, oxidize with nitric 
 acid, heat with about 80 cc of sulphuric acid until fumes are 
 evolved, finally cool, and dilute to 1,000 cc, set on steam bath, 
 unti] dissolved, and filter if necessary. Add o.1 N permanga- 
 nate solution until a faint pink color shows that any ferrous iron ~ 
 has been oxidized. Ferric ammonium sulphate may also be used’. 
 
 *International Atomic Weights, 1921-22. 
 7Gooch, Methods in Chemical Analysis, rst ed., p. 426. 
 
Specification for Titanium Pigment. 1I 
 
 (7) STANDARD FERRIC SULPHATE SOLUTION FOR COLORIMET- 
 RIC DETERMINATION OF IRON.—Determine the strength of the 
 ferric solution reagent used in 5 (2) in terms of iron and dilute 
 this solution until one is obtained of the strength 1 cc=0.00001 
 g Fe, 
 
 (k) Porasstum THIOCYANATE INDICATOR.—Prepare a 2 per 
 cent solution of the pure salt in distilled water. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
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 WASHINGTON, D. C. 
 AT 
 
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 U. S. Gov't 
 Master 
 Specification, 
 
 No. 137a 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 165 
 
 [2d ed. Issued April 29, 1927] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 PAINT, OLIVE DRAB (SEMIPASTE AND READY-MIXED) 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 137a 
 [Revised September 2, 1925] 
 
 This specification was officially adopted by the Federal Specifications Board 
 on May 1, 1924, for the use of the departments and independent establish- 
 ments of the Government in the purchase of olive drab paint (semipaste and 
 ready mixed). 
 
 [The date on which the technical requirements of this revision of this specification became mandatory 
 for all departments and independent establishments of the Government was September 2, 1925. The changes 
 
 included in this revision were authorized by the Federal Specifications Board and promulgated in a circular 
 letter on above revision date.] 
 
 CONTENTS 
 Page 
 I. General specifications__._.______________ See er ec ee ok, wee 2 
 erence SSS SBS hattte Shek Wy Dees a? eet) ee 2 
 Pena wminl firth Oe £oL Ce _ De pAe GIG. sel Devse to 5! 2 
 .Vuaseneral requirements wo... wk ee eek dei ote os 2 
 SRE ES a ae ae SOC 2 mee Cale pee,” TALE 2 
 BS) IT eld gag AiR eiaeala gl ass Yes Ste Waki” Silo, Ge a pill naling 2 
 PI Sk. Wh Ue ae ee on Sle Oe BED oe ee ee 3 
 me wrcmmipastens OF ils NV IS LORE! AU See ee ae ee 3 
 4 iiReddy-mined paintoclue) 22001 5. CAO. BA AO 3 
 VI. Methods for sampling and testing._._.__.-__-..__-----_..- Lu Le 4 
 1 RE SALES Te ge il Mth ARGUS eae Saaeies ree Remo ce TORS eer YH ee 4 
 2. Laboratory examination, semipaste _.___..._-..._----___- 4 
 eRe Ce IS Cl CT eras srerasie aig nat ns Ermer lanes vi 
 4. Laboratory examination, ready-mixed paint_-..________.___ 9 
 Si Menpenteces re 9G. 2 Sele SL aa 10 
 VII. Packing and marking of shipments.__.-...-....------.---.---.-< 12 
 
 Ee OE Oe a RE OTE ae ee reed aa eG Ok RE eA CG Riis bm Gees Pe 
 43231°—27 : 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification : 
 II, CLASSES 
 
 Olive drab paint shall be of the following classes: Semipaste in 
 linseed oil and ready mixed. 
 
 III. MATERIAL 
 See detail requirements. 
 IV. GENERAL REQUIREMENTS 
 See detail requirements. 
 
 V. DETAIL REQUIREMENTS 
 1, PIGMENT 
 
 The pigment shall be composed of: 
 
 Ingredients Maximum | Minimum 
 Per cent Per cent 
 White lead (basic carbonate, basic sulphate, or a mixture thereof) ........-.....-|.---------.. 35 
 Zine'oxide (ZnO) ow ca coco dcado node scene ck wanes uebeeo en ee eee eee ee Rap 30 
 White mineral pigments (containing no lead or zinc compounds), pure tinting 
 eolors,,or.any: mixture thereof sc 22. bs eal ss 2 ails Jose seue2 ee 80 76 Bias. 
 Organic CONOES gcc he cs ee a None@isleseadsetenwd- 
 
 Balphide shlphur. pw snnenpeeeenpergecwsn= pena wanenechna eee None, wo-neeense=- 
 
 In no case shall the sum of the basic lead carbonate, basic lead 
 sulphate, and zinc oxide be less tham 70 per cent. The lead and 
 zinc pigments may be introduced in the form .of any mixture pre- 
 ferred of basic carbonate white lead, basic sulphate white lead, zinc 
 oxide, or leaded zinc, provided the above requeet ees as to ee 
 sition are met. 
 
 The difference between the total lead weighed as taal iSitiphate 
 ind the lead sulphate equivalent to the chromium found, multiplied 
 by the factor 0.883, shall be considered white lead. It is not possible 
 to determine the amount of lead carbonate and lead sulphate when 
 carbonates or sulphates of other metals, such as calcium, ‘are present. 
 Also neither basic lead carbonate nor basic lead sulphate is a definite 
 compound. The factor to convert PbSO, to (PbCO;). Pb(OH), is 
 0.854, to convert PbSO, to PbSO,PbO is 0.868, and to convert PbSO, 
 to (PbSO,), PbO is 0.913. The arbitrary factor used under this 
 specification is the mean of the largest and smallest of these three 
 factors. 
 
—_ ees ee a or? | ei 
 
 a ee. eee ee ee ee ee 
 
 SPECIFICATION FOR OLIVE DRAB PAINT 3 
 2. LIQUID 
 
 The liquid in semipaste paint shall be entirely linseed oil; in ready- 
 mixed paint it shall contain not less than 85 per cent linseed oil, the 
 remainder to be combined drier and thinner. ‘The thinner shall be 
 turpentine, volatile mineral spirits, or a mixture thereof. 
 
 3. SEMIPASTE 
 
 Semipaste shall be made by thoroughly grinding the pigment 
 with linseed oil. 
 
 The semipaste as received, and three months thereafter, shall be 
 not caked in the container and shall break up readily in linseed oil to 
 form a smooth paint of brushing consistency. It shall mix readily 
 with linseed oil, turpentine, or volatile mineral spirits, or any com- 
 bination of these substances, in all proportions without curdling. 
 The color and hiding power when specified shall be equal to those of 
 a sample mutually agreed upon by buyér and seller. The weight 
 per gallon shall be not less than 18 pounds. The paste shall con- 
 sist of: 
 
 Ingredients Maximum } Minimum 
 
 : Per cent Per cent 
 PRE Se ME Te Re NGS a, eae ite RE eR ee a Se Rm MRI aE Pe EY ee a oe iy feeeal 
 
 LOO S SEG, CH kl ae 5! ep Se 0 i ll let ak A Sd ie SR ee oe Red EL, oa 27 23 
 
 MIGISLUPE.and ener volatile amaitet 202042225 oa FS lees eb So ieee oa 
 
 Coarse particles and ‘‘skins’’ (total residue retained on No. 325 sieve based on 
 ee ce haiichn ena teamed eh auy 2 OWN es eee 
 
 4, READY-MIXED PAINT 
 
 ’ Ready-mixed paints shall be well ground, shall not settle badly or 
 cake in the container, shall be readily broken up with a paddle to a 
 smooth uniform paint of good brushing consistency, and shall dry 
 within 18 hours to a full oil gloss without streaking, running, or 
 sagging. The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller. The 
 weight per gallon spine be not less than 15 pounds. The paint shall 
 consist of: 
 
 Ingredients Maximum |} Minimum 
 
 Per cent Per cent 
 66 62 
 
 Oe ow ww ww we we ow Oe SEES EE SSE SEERA SAT SOOO EME 
 
 nn a ww a nn en eer se rn tren anne enna aeseere 
 
 Catiee particles and ‘‘skins” (total residue retained on No. 325 sieve based on | 
 i octign ot nr anccnbnnnasnwigamsderneasyannginnchas=<g amen wane cian eee bh Wa ges apicye ey a 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 VI. METHODS FOR SAMPLING AND TESTING / 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 available information to ascertain whether the material meets the 
 specification. : 
 
 1, SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package out 
 of each lot of not more than 1,000 packages shall be taken as repre- 
 sentative of the whole. Whenever possible an original unopened 
 container shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine by thorough testing 
 with a paddle or spatula whether the material meets the requirement 
 regarding caking in the container. He shall then thoroughly mix 
 the contents of the container and draw a sample of not less than 5 
 pounds of the thoroughly mixed paint, place it in a clean, dry metal 
 or glass container, which must be filled with the sample, closed with 
 a tight cover, sealed, marked, and sent to the laboratory for test with 
 the inspector’s report on caking in container. 
 
 When requested, a duplicate sample may be taken from the same 
 package and delivered to the seller, and the inspector may take a 
 third sample to hold for test in case of dispute. 
 
 2. LABORATORY EXAMINATION, SEMIPASTE 
 
 (a) Caxine In ConTaIneR.— When an original package is received 
 in the laboratory it shall be weighed, opened, and stirred with a stiff 
 spatula or paddle. The paste must be no more difficult to break up 
 than a normal good grade of semipaste paint. The semipaste shall 
 finally be thoroughly mixed, removed from the container, and the 
 container wiped clean and weighed. This weight subtracted from 
 the weight of the original package gives the net weight of the con- 
 tents. A portion of thoroughly mixed semipaste shall be placed in 
 a clean container and the portions for the remaining tests promptly 
 weighed out. 
 
 (6) Weicut pER GaLLon.—From the weight of a known volume 
 of the paste calculate the specific gravity, which multiplied by 8.33 
 gives the weight in pounds per gallon. Any suitable container of 
 known volume may be used for the purpose, but a short cylinder of 
 heavy glass with rounded bottom about 75 mm high and having 
 a capacity of from 125 to 175 cc (a glass cap to keep dust from re- 
 agent bottle stopper) is a convenient vessel for the purpose. The 
 capacity of this vessel is determined to within 1 cc. The paste is 
 packed into it until completely full, the top leveled off smooth with a 
 spatula, and weighed to plus or minus 0.5 g. Subtract the weight of 
 the empty container and divide the remainder by the number of 
 
: 
 % 
 | 
 ay 
 | 
 4 
 4 
 ’ 
 | 
 : 
 ] 
 4 
 
 SPECIFICATION FOR OLIVE DRAB PAINT 5 
 
 cubic centimeters representing the capacity of the container. The 
 quotient is the specific gravity, which can be thus determined within 
 plus or minus 2 in the second decimal place. | 
 
 (c) Mrxine with LinsrEep O1i.—One hundred grams of the paste 
 shall be placed in a cup, 18 cc of linseed oil added slowly with care- 
 ful stirring and mixing with a spatula or paddle. The resulting mix- 
 ture must be smooth and of good brushing consistency. 3 
 
 (d) Couor.—To the mixture made, in (c), add 3 cc of drier 
 (F. S. B. No. 20) and mix thoroughly. Prepare a mixture of the 
 standard paste with 18 cc of linseed oil and 3 cc of drier, using the 
 same linseed oil and drier for both lots of paint. Apply both paints 
 on clean metal or glass so that the edges touch one another. Let 
 dry and compare the colors. 
 
 (ec) Moisturn aNp Oruer Votatite Matter.—Weigh accurately 
 from 3 to 5 g of the paste in a tared flat-bottomed dish about 8 
 em in diameter, spreading the paste over the bottom. Heat at 105 
 to 110° C. for three hours, cool, and weigh. Calculate the loss in 
 weight as the percentage of moisture and volatile matter. 
 
 (f) Percentace or Pigmunr.—Weigh accurately about 15 g of 
 the paste in a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
 traction mixture’? (see Reagents), mix thoroughly with a glass rod, 
 wash the rod with more of the extraction mixture, and add enough 
 of the reagent to make a total of 60 cc in the tube. Place the tube © 
 in the container of a centrifuge, surround with water, and counter- 
 balance the container of the opposite arm with a similar tube or 
 a tube with water. Whirl at a moderate speed until well settled. 
 Decant the clear supernatant liquid, repeat the extraction three times 
 with 40 cc of extraction mixture. After drawing off the extraction 
 mixture, set the tube in a beaker of water at about 80° C. or on 
 top of a warm oven for 10 minutes, then in an oven at 105 to 110° 
 C. for two hours. Cool, weigh, and calculate the percentage of 
 pigment. Grind the pigment to a fine powder, pass through a 
 No. 80 sieve to remove any skins, and preserve in a stoppered bottle. 
 
 (g) Preparation or Farry Acips.—To about 25 g of the paste in 
 a porcelain casserole, add 15 cc of aqueous sodium hydroxide (see 
 Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on a 
 steam bath until saponification is complete (about one hour), Add 
 100 ec of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
 10 cc in excess), boil, stir, and transfer to a separatory funnel to 
 which some water has been previously added. Draw off as much as 
 possible of the acid aqueous layer and lead sulphate precipitate, wash 
 once with water, then add‘50 cc of water and 50 cc of ether. Shake 
 very gently with a whirling action to dissolve the fatty acids in 
 the ether, but not so violently as to form an emulsion. Draw 
 off the aqueous layer and wash the ether layer with one 15 cc por- 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 tion of water and then with 5 cc portions of water until free from 
 sulphuric acid. Then draw off the water layer completely. Transfer 
 the ether solution to a dry flask and add 25 to 50 g of anhydrous 
 sodium sulphate. Stopper the flask and let stand with occasional 
 shaking at a temperature below 25° C. until the water is completely 
 removed from the ether solution, which will be shown by the solu- 
 tion becoming perfectly clear above the solid sodium sulphate. De- 
 cant this clear solution, if necessary, through a dry filter paper into 
 a dry 100 cc Erlenmeyer flask. Pass a rapid current of dry air 
 (pass through a CaCl, tower) into the mouth of the Erlenmeyer 
 flask and heat to a temperature below 75° C. on a dry, hot plate 
 until the ether is entirely driven off. 
 
 It is important to follow all of the details, since ether yerioncly con- 
 tains alcohol, and after washing with water always contains water. 
 It is very difficult to remove water and alcohol by evaporation from fatty 
 acids, but the washing of the ether solution and subsequent drying with 
 anhydrous sodium sulphate removes both water and alcohol. Ether, in 
 the absence of water and alcohol, is easily removed from fatty acids by 
 gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (hk) Test ror Minera Orn aND OTHER UNSAPONIFIABLE Mart- 
 TER.—Place 10 drops of the fatty acid (g) in a 50 cc test tube, add 
 5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes, 
 add 40 cc of water, and mix; a clear solution indicates that not more 
 than traces of unsaponifiable matter are present. If the i eters _ 
 not clear, the oil is not pure linseed oil. 
 
 (1) IoprineE Numper or Farry Acips.—Place a small qeaititd of 
 the fatty acids, (g), in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping from 0.09 to 0.15 g into a 500 ce 
 bottle having a well-ground glass stopper, or an Erlenmeyer flask 
 having a specially flanged neck for the iodine test. Reweigh the 
 burette or beaker and determine the amount of sample used. Add 
 10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
 10 cc of chloroform to each of two empty bottles like that used for 
 the sample. Add to each bottle 25 ce of the Wijs solution (see 
 Reagents) and let stand with occasional shaking for one hour in a 
 dark place at a temperature of from 21 to 23°C. Add 10 ee of the 
 15 per cent potassium iodide solution and 100 cc of water, and titrate 
 with standard sodium thiosulphate, using starch as indicator. The 
 titrations on the two blank tests should agree within 0.1 cc. From 
 the difference between the average of the blank titrations and the 
 titration on the sample and the iodine value of the thiosulphate 
 solution, calculate the iodine number of the sample tested. (lodine 
 
SPECIFICATION FOR OLIVE DRAB PAINT 7 
 
 number is centigrams of iodine to 1 g of sample.) If the iodine 
 number is less than 175, the oil does not meet the specification. 
 
 (7) Coarse Partictes anp Sxins.—Dry in an oven at 105 to 
 110° C. a No. 325 sieve, cool, and weigh accurately. Weigh an 
 am punt of semipaste containing 10 ¢ of pigment (See VI, 2 (f)), add 
 100 cc of kerosene, mix thoroughly, and wash with kerosene through 
 the sieve, breaking up all lumps, but not grinding. After washing 
 with kerosene until all but the particles too coarse to pass the sieve 
 have been washed through, wash all kerosene from the sieve with 
 ether or petroleum ether, heat the sieve and contents for one hour at 
 105 to 110° C., cool and weigh. 
 
 3. ANALYSIS OF PIGMENT 
 
 (a) QuaLITATIVE ANALyYsIs.—A complete qualitative analysis, fol- 
 
 lowing the well-established methods, is always advisable. Test a 
 
 portion of the pigment with hydrochloric acid (1:1). No odor of 
 hydrogen sulphide should develop. Boil, dilute, filter, and test 
 the filtrate for metals other than lead and zinc (especially calcium 
 and barium). The absence of calcium in this filtrate indicates that 
 the extending pigments contain no calcium carbonate or calcium sul- 
 phate; the absence of barium indicates that the extending pigments 
 contain no barium carbonate. To test for chromate, boil another 
 small portion of the pigment with dilute nitric acid, filter, cool, and 
 add to the filtrate a few cubic centimeters of ether and a few drops of 
 hydrogen peroxide; stir, let stand until the ether layer separates. If 
 this layer is deep blue, chromium is indicated. Test for Prussian blue 
 (which is rarely present) by boiling a portion of the pigment with 
 sodium hydroxide solution. A yellow or yellow-brown precipitate 
 with a yellow liquid above it should result. Filter, add to the 
 filtrate a mixture of ferric and ferrous salts, and render acid with 
 dilute hydrochloric acid. A blue color indicates the presence of 
 Prussian blue in the sample. 
 
 (6) Waitt Leav.—Weigh accurately about 1 g of the pigment, 
 transfer to a 250 cc beaker, moisten with a few drops of alcohol, add 
 slowly 25 cc of concentrated hydrochloric acid, cover, and boil for 
 5 to 10 minutes. Dilute to about 150 cc with hot water and boil 
 for 5 to 10 minutes. Filter on paper or on a Gooch crucible, and 
 wash the insoluble residue thoroughly with hot water. Discard the 
 residue for quantitative purposes. Nearly neutralize with ammonia 
 the filtrate from the insoluble matter, dilute to about 300 cc and pass 
 into the clear solution a rapid current of hydrogen sulphide to com- 
 plete precipitation, let the sulphide of lead settle, filter on paper, 
 wash with water containing some hydrogen sulphide, dissolve the 
 sulphide in hot nitric acid (1:3), add 10 cc of sulphuric acid (1:1), 
 evaporate until copious fumes of sulphuric anhydride are evolved; 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 cool, add about 75 cc of water, and then about 75 cc of 95 per cent 
 ethyl alcghol. Stir, let settle, filter on a Gooch crucible, wash with 
 dilute alcohol, dry, ignite, and weigh as PbSO,. Subtract the lead 
 sulphate equivalent of the total chromium as found below, (c), multi- 
 ply the remaining PbSO, by the factor 0.883 and report as white lead. 
 
 (c) Toran CHromium.—Heat the filtrate from the lead sulphide 
 to expel hydrogen sulphide.. Cool, add sodium peroxide, keeping the © 
 beaker covered, in sufficient amount to render the solution alkaline ~ 
 and to oxidize the chromium to chromate. Boil until all the hydro- 
 gen peroxide is driven off, cool, acidify with sulphuric acid (1:4), 
 add a measured excess of a freshly prepared solution of ferrous sul- 
 phate, and titrate the excess of ferrous iron with standard potassium 
 dichromate, using potassium ferricyanide solution as outside indica- 
 tor. Titrate a blank of an equal volume of the ferrous sulphate solu- 
 tion with the standard potassium dichromate. From the difference 
 between the titration on the blank and on the sample, calculate the 
 chromium in the sample to PbCrO,. From the PbCrO, found, cal- 
 culate the equivalent. of PbSO, by multiplying by the factor 0.938. 
 
 (<4) Zinc Oxipn.—Weigh accurately about 1 g of the pigment, 
 transfer to a 250 cc beaker, moisten with alcohol, add 30 ce of hydro- 
 chloric acid (1:2), boil for two or three minutes, add about. 100 
 cc of water, let settle, and filter on paper; to the filtrate add about 
 2 g of ammonium chloride and strong ammonia. until slightly alka- 
 line (the latter to precipitate out any iron present), set on the steam 
 bath to settle, filter into a 400 cc beaker, wash the precipitate once 
 with water, remove the beaker and dissolve the iron hydroxide 
 with dilute hydrochloric acid, catching the ferric chloride in a 250 
 cc beaker, add to this filtrate 1 g of ammonium chloride and make 
 ammoniacal, let settle, filter and wash thoroughly with hot water, 
 catching the filtrate and washings in the original 400 cc beaker, 
 reserved from the first precipitation. Add a small piece of litmus 
 paper. Render the filtrate first acid with hydrochloric acid, then 
 add 3 cc of strong hydrochloric acid, heat nearly to boiling, and 
 titrate with standard ferrocyanide, as in standardizing that solution 
 (see Reagents). Calculate total zinc as zinc oxide. 
 
 (e) Organic Cotorine Marrer.—(A. S. 7. M. Standards, 1921, 
 ».690.)—Test the pigment successively with hot water, 95 per cent 
 alcohol, alcoholic sodium hydroxide, and acetic acid. Chloroform, 
 sodium hydroxide, sulphuric acid, hydrochloric acid-stannous chloride 
 solution, and other reagents may be tried. The solutions should 
 remain colorless. The presence of an organic color may. often be 
 detected by the characteristic, odor given off on ignition. — 
 
 (f) CaucuLations.—Add the percentage of white lead (see VI, 3, 
 (b)), zine oxide (see VI, 3, (d)), and subtract from 100; the remain- 
 der is reported as extending and tinting pigment. ' 
 
Se ee Se ee eee Se 
 
 a ee ee 
 
 Pe) aera een ee eS ee 
 
 SPECIFICATION FOR OLIVE DRAB PAINT 9 
 4, LABORATORY EXAMINATION, READY-MIXED PAINT 
 
 (a2) Caxine 1n Contarner.—Follow the procedure outlined in 
 VI, 2 (a), noting that the paint should be no more difficult to break 
 up than a good grade of mixed paint. 
 
 (6) Wxicut PER GaLton.—Weigh a clean, dry, 100 cc graduated 
 flask. Fill to the mark with the thoroughly mixed paint and weigh 
 again. The increase in weight expressed in grams divided by 100 
 gives the specific gravity, which multiplied by 8.33 gives the weight 
 in pounds per gallon. 
 
 (c) BrusHinc Propertizs anp Time or Dryine.—Brush this 
 well-mixed paint on a suitable panel, which may be ground glass, 
 steel, or well-filled wood. Note whether the paint works satis- 
 factorily under the brush. Place the panel in a vertical position 
 in a well-ventilated room and let stand for 18 hours. The paint 
 should be dry and free from streaks. Flow a portion of the paint 
 on a clean glass plate. Let dry in a nearly vertical position at room 
 
 temperature (65 to 100° F.). The film shall show no streaking or 
 
 separation within a distance of 4 inches from the top. 
 
 “(d) Cotor.—Paint the sample and the standard on clean metal 
 or glass so that the edges touch one another. Let dry and compare 
 colors. 
 
 (ec) WarEer.—Mix 100 g of the paint in a 500 cc short neck glass 
 flask! with 75 cc of toluol (free from water). Connect with the dis- 
 tilling trap and condenser and heat so that the condensed distillate 
 falls from the end of the condenser at the rate of from two to five 
 drops per second. Continue the distillation at the specified rate 
 until no water is visible on any part of the apparatus except at the 
 bottom of the trap. This operation usually requires less than an 
 hour. A persistent ring of condensed water in the condenser tube 
 should be removed by increasing the rate of distillation for a few 
 minutes. The number of cubic centimeters of condensed water 
 measured in the trap at room temperature is the percentage of water 
 in the paint. 
 
 (f) Vouatits Tutnner.—Follow the procedure outlined in VES 
 (e). Correct the result for any water found (see VI, 4 (e)) and re- 
 port the remainder as volatile thinner. 
 
 (g) Percentacs or Piement.—Follow the procedure outlined in 
 VI, 2, (f). 
 
 (h) Tustinc Nonvouatite Veuicte.—Follow the procedure out- 
 lined in V, 2 (g), (4), and (i), except that in the preparation of the 
 fatty acids the mixture of paint and alkali is heated on the steam 
 bath until all volatile thinner is driven off. 
 
 1 The apparatus for determining water is that described in ‘Standard method of test for water in petro- 
 
 leum products and other bituminous materials,” serial designation D-95-24, A. 8. T. M. Standards, 1924, 
 p. 901 and Figure 1 (6) and (¢), p. 902. 
 
10 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (2) Coarse Particues anp Sxins.—Follow the procedure outlined 
 in VI, 2 (9). 
 (Gj) Testine Prement.—Follow the procedure outlined in VI, 3 (a) 
 
 to (f), inclusive. 
 5. REAGENTS 
 
 (a) Uranyy InpicaTor ror Zinc Titration.—A 5 per cent solu- 
 tion of uranyl nitrate in water or a 5 per cent solution of uranyl 
 acetate in water made slightly acid with acetic acid. 
 
 (6) Sranparp Potassium FrrrocyanipE.—Dissolve 22 g of the 
 pure salt in water and dilute to 1,000 cc. To standardize, transfer 
 about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
 ignited pure zinc oxide to a 400 cc beaker. Dissolve in 10 cc of 
 hydrochloric acid and 20 cc of water. Drop in a small piece of litmus 
 paper, add ammonium hydroxide until slightly alkaline, then add 
 hydrochloric acid until just acid, and then 3 cc of strong hydrochloric 
 acid. Dilute to about 250 cc with hot water and heat nearly to 
 boiling. Run in the ferrocyanide solution slowly from a burette 
 
 with constant stirring until a drop tested on a white porcelain plate 
 " with a drop of the uranyl indicator shows a brown tinge after standing 
 one minute. A blank should be run with the same amounts of 
 reagents and water as in the standardization and in titration of the 
 sample. The standardization must be made under the same condi- 
 tions of temperature, volume, and acidity as obtained when inp 
 sample is titrated. 
 
 (c) StaNDARD Sopium THIOSULPHATE SOLUTION. Dimes pure 
 sodium thiosulphate in distilled water (that has been well boiled to 
 free it from carbon dioxide) in the proportion of 24.83 g of crystal- 
 lized sodium thiosulphate to 1,000 cc of the solution. It is best to 
 let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Treadwell-Hall, 
 Analytical Chemistry, vol. 2, 6th ed., p. 551.), This solution will be 
 approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust 
 it to exactly decinormal. Preserve in a stock bottle provided with 
 a guard tube filled with soda lime. 
 
 (d) Strarcu Sotution.—Stir up 2 to 3 g of noha BNR or 5 g 
 of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
 add 300 to 400 cc of boiling water, and boil the mixture untit the 
 starch is practically dissolved, then dilute to 1 liter. 
 
 (e) Extraction Mixtrurs.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes bénzol. 
 
 4 volumes methyl alcohol. 
 
 1 volume acetone. 
 
a ee Se Le a ee A ae Se ll 
 
 SPECIFICATION FOR OLIVE DRAB PAINT 11 
 
 (f) Aqgurnous Soprum Hyproxinz.—Dissolve 100 ¢g of sodium hy- 
 droxide in distilled water and dilute to 300 ce. 
 (g) Porasstum lopipr So.tution.—Dissolve 150 g of potassium 
 
 ‘iodide free from iodate in distilled water and dilute to 1,000 cc. 
 
 (h) Wiis Sotution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine or more particularly 
 of chlorine over that required to form the monochloride. This con- 
 dition is most satisfactorily attained by dissolving in the whole of 
 the acetic acid to be used the requisite quantity of iodine, using 
 
 gentle heat to assist the solution, if it is found necessary. Dissolve 
 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
 and is free from reducing impurities in the proportion so that 13 ¢g 
 of iodine will be present in 1,000 cc of solution. Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the 
 remainder until the halogen content of the solution is doubled. 
 Ordinarily it will be found that by passing the chlorine into the 
 main part of the solution until the characteristic color of free iodine 
 has just been discharged, there will be a slight excess of chlorine 
 which is corrected by the addition of the requisite amount of the 
 unchlorinated portion until all free chlorine has been destroyed. A 
 slight excess of iodine does little or no harm, but excess of chlorine 
 must be avoided. 
 
 (1) Anconotic Sopium Hyproxipr SoivutTion.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 
 the clear liquid into another bottle and keep well stoppered. This 
 solution should be colorless or only slightly yellow when used, 
 and it will keep colorless longer if the alcohol is previously treated 
 with sodium hydroxide (about 80 g to 1,000 cc), kept at about 
 50° C. for 15 days, and then distilled. 
 
 (7) StaNDARD Frrrovus SuntpHate Souution.—Dissolve 14 g 
 of pure crystallized ferrous sulphate (FeSO,7H.O) in about 500 
 cc of water to which 25 cc of concentrated H,SO, has been added, 
 and then dilute to 1,000 cc. This solution should be freshly stand- 
 ardized when needed, as it does not keep well. 
 
 (ek) StanpaRD Porasstum DicHromMatTE So.utrion.—Dissolve 
 4.903 g of pure, dry, crystallized potassium dichromate in water 
 and dilute to 1,000 cc. One cubic centimeter of this solution corre- 
 sponds to 0.0108 g PbCrQ,, or 0.0101 g PbSO,. This solution may 
 be checked by determining its iron value on Bureau of Standards 
 Standard Sample No. 27a, Sibley Iron Ore. 
 
12 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (7) Porasstum Frrricyanripr SoLtutTion.—Dissolve a piece of 
 potassium ferricyanide half as big as a small pea in 50 cc of water. 
 This solution must be made fresh when wanted, because it does not 
 keep. ease : 
 
 VII. PACKING AND MARKING OF SHIPMENTS ibe 
 
 Shall be in accordance with commercial practice unless otherwise 
 specified. 
 VIII. NOTES 
 
 This specification covers the requirements for a high-grade olive- 
 drab paint for outside and general use. It may be ordered either in 
 the form of semipaste pigment ground in linseed oil or of ready- 
 mixed paint, and the purchaser shall state which is desired. The 
 semipaste may be purchased by net weight or by volume. The 
 ready-mixed paint should be purchased by volume (231 cubic inches 
 to the gallon). ? 
 
 For formulas and methods of using this material and information 
 regarding the use of other specification paint materials see Bureau 
 of Standards Technologic Paper No. 274, entitled “Use of United 
 States Government Specification Paints and Paint Materials,” 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 § CENTS PER COPY 
 Vv 
 
U. S. Gov't 
 Master 
 Specification 
 
 No. 278 
 DEPARTMENT OF COMMERCE 
 
 BUREAU OF STANDARDS 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 215 
 {Issued May 9, 1925] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 OUTSIDE WHITE TITANIUM-ZINC PAINT, SEMIPASTE AND 
 READY-MIXED 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 278 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on May 8, 1925, for the use of the Departments and Independent 
 Establishments of the Government in the purchase of outside white titanium- 
 zinc paint, semipaste and ready-mixed. 
 
 CONTENTS 
 Page 
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 Se NEUE RL RST EATS COTTA i a cere aes pt diigo es alll ld ene y 
 : bE) aR ee SN Aegean ay eS ee AO ANSE Sere Sine A Ae ee ae NE 2 
 A a Sash le ons Pea tamale eed eho Sd ih ene 2 
 permrrenaye rin eile es Oe es as ee a ee lay i Z 
 marenuyanited paints S25.) ee ee ewe ee 3 
 eeetnome or semnling and testing... <n. obec ee ate ee en 3 
 0 DESO 96) GRO Sie ACS SERRE Ge ee Ra Oa ae oe Ae cee ps ae 3 
 2. Laboratory examination, semipaste___._______.___________ 4 
 sana lyoie Of pitnetit. Ursi ie 23 le Ae Se ie 6 
 4, Laboratory examination, ready-mixed paint______________ 8 
 Shia OTE 2 i id oh en iio i i peed 10 
 SR SIE Sele ce Dd 9b 1 gat RnR, SiR egaRON pec i Sar NOE eae aan a MEN Se 12 
 Mtr SePraCLAT AOL ETOEINA CLOT oe ee ees 12 
 WORE ET PIE SCC ITIOR LIOLIS cies ke a Sm pe a ep nh et oe wel 12 
 
 I. CLASSES 
 
 Outside white titanium-zinc paint shall be of the following classes: 
 Semipaste in linseed oil and ready-mixed. 
 43781°—25 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 Il. MATERIAL 
 No details specified. 
 III. GENERAL REQUIREMENTS 
 No details specified. 
 IV. DETAIL REQUIREMENTS 
 1. PIGMENT 
 
 _ The pigment shall be composed of: 
 
 Ingredients 
 
 fxtending Pigments, 5... sc.05.0hhnahstendases 5 dbas == Skee a ae 
 
 ean eee eee ee Oe we ee RH EO ee RE ES SR RE eee 
 
 In no case shall the sum of the titanium pigment and zine oxide 
 be less than 90 per cent. The titanium pigment shall contam 25 
 per cent titanium oxide, the remainder to be blanc fixe (precipi- 
 tated barium sulphate). 
 
 2. LIQUID 
 
 The liquid in semipaste paint shall be entirely linseed oil; in 
 ready-mixed paint it shall contain not less than 85 per cent linseed 
 oil, the remainder to be combined drier and thinner. The drier 
 shall be free from lead. The thinner shall be turpentine, volatile 
 mineral spirits, or a mixture thereof. “rs 
 
 3. SEMIPASTE 
 
 Semipaste shall be made by thoroughly grinding the pigment 
 with linseed oil. 
 
 The semipaste as received, and three months thereaiter, shall be 
 not caked in the container and shall break up readily in linseed 
 oil to form a smooth paint of brushing consistency. It shall mix 
 readily with linseed oil, turpentine, or volatile mineral spirits or 
 any combination of chase substances, in all proportions without 
 curdling. The color and hiding power when specified shall be equal 
 to those of a sample mutually agreed upon by buyer and seller. 
 The weight per gallon shall be not less than 1714 pounds. The 
 semipaste shall consist of; 
 
eS. hl Ae = 
 
 OUTSIDE WHITE TITANIUM-ZINC PAINT 8 
 
 Ingredients Maximum | Minimum 
 
 Per cent Per cent 
 75 
 
 1 AE a 3S ASR. SE Sa a et ea art ae neteies Peal et 70 
 NE NE EO ark Ci Ss CaM w oid ena nt hc. cater o®aedoaldcwaata 30 25 
 Romer Wy TCIM Stree Aire ee ee ee es ea en ae ee ee NOn6. 1... cakecaties 
 Moisture and other volatile matter Pe ad oie Sane Le aee soa eae eGn See boaete steep ot OST (acess. Se 
 Coarse particles and ‘‘skins’”’ (total residue retained on No. 325 sieve based on 
 
 CE gE SE DID. EE Sy OE TER Say A Sn ee eee VM Mig SAP Senay, ego 
 
 4. READY-MIXED PAINT 
 
 Ready-mixed paint shall be well ground, shall not settle badly 
 or cake in the container, shall be readily broken up with a paddle 
 to a smooth, uniform paint of good brushing consistency, and shall 
 dry within 18 hours to a full oil gloss, without streaking, running, 
 or sagging. The dried film shall be resistant to sulphide fumes. 
 The color and hiding power when specified shall be equal to those 
 of a sample mutually agreed upon by buyer and seller. The weight 
 per gallon shall be not less than 14 pounds. The paint shall con- 
 sist of : 
 
 Ingredients Maximum | Minimum 
 
 Per cent Per cent 
 OUTS STG SU SDD oO Oe en aR ae en etre a 62 58 
 
 Liquid Csaatatgtae at least 85 per cent linseed Onpisreee ) SONS a ek PLES 42 38 
 NE SEIS Sep eR SOPRA tas ip eT oe eS eee N anes ae. Na oe 
 PRM eneE soe weet oe ae eel NS Ere SL as A ee cits’ 2G BT eee 
 
 Coarse particles and ‘‘skins’”’ (total residue retained on No. 325 sieve based on 
 
 jus | SRG) boats DSU RE ae he wae) See COS Meo D8 eee ae oD Le ee On LE Ieee. SD | dukteccalpe 
 
 V. METHODS FOR SAMPLING AND TESTING 
 
 Delweries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 
 available information to ascertain whether the material meets the 
 
 specifications. 
 1, SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible an original un- 
 opened container shall be sent to the laboratory, and when this is for 
 any reason not done, the inspector shall determine by thorough 
 testing with a paddle or spatula whether the material meets the 
 requirement regarding caking in the container. We shall then thor- 
 oughly mix the contents of the container and draw a sample of not 
 less than 5 pounds of the thoroughly mixed paint, place it in a 
 clean, dry metal or glass container, which must be filled with the 
 sample, closed with a tight cover, sealed, marked, and sent to the 
 
 laboratory for test with the inspector’s report on caking in con- 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 tainer. When requested, a duplicate sample may be taken from 
 the same package and delivered to the seller, and the inspector may 
 take a third sample to hold for test in case of dispute. 
 
 2. LABORATORY EXAMINATION, SEMIPASTE 
 
 (az) Caxrne in Contatner.—When an original package is received 
 in the laboratory it shall be weighed, spend and stirred with a 
 stiff spatula or paddle. The paste must be no more difficult to 
 break up than a normal good grade of semipaste paint. The semi- 
 paste shall finally be thoroughly mixed, removed from the container, 
 and the container wiped clean and weighed. This weight subtracted 
 from the weight of the original package gives the net weight of the 
 contents. A portion of thoroughly mixed semipaste shall be placed 
 in a clean container and the portions for the remaining tests pr omptly 
 weighed out. 
 
 (6) Wricur per Gatton.—From the weight of a known volume 
 of the paste calculate the specific gravity, which multiphed by 8.33 
 gives the weight in pounds per gallon. Any suitable container of 
 known volume may be used for the purpose, but a short cylinder of 
 heavy glass with rounded bottom about 75 mm high and having 
 a capacity of from 125 to 175 cc (a glass cap to keep dust from 
 reagent bottle stopper) is a convenient vessel for the purpose. The 
 capacity of this vessel is determined to within 1 ec. The paste is 
 packed into it until completely full, the top leveled off smooth with 
 
 a spatula, and weighed to plus or minus 0.5 g. Subtract the weight 
 of the empty container and divide the remainder by the canes of 
 cubic centimeters representing the capacity of the container. The 
 quotient is the specific gravity, which can be thus Tt npn 
 plus or minus 2 in the second decimal place. 
 
 (c) Mrxinc Wirn Linszep Om.—One hundred gen of ‘the 
 paste shall be placed in a cup, 18 cc of linseed oil added slowly with 
 careful stirring and mixing with a spatula or paddle. The resulting 
 mixture must be smooth ad of good brushing consistency. _ 
 
 (d) Cotor.—Place some of the paste on a clean, clear glass plate. 
 Place some of the standard agreed upon beside the sample on the 
 plate, turn the glass over, and compare the colors. 
 
 (e) Moisture AND Oral. Voratite Marrer.—Weigh accurately 
 from 8 to 5 g of the paste in a tarred flat-bottomed dish about 8 cm 
 in diameter, spreading the paste over the bottom. Heat at 105 to 
 110° C. for three hours, cool, and weigh. Calculate the loss in weight 
 as the percentage of moisture and volatile matter. 
 
 (f) Percentace or Pigment.—Weigh accurately about 15. g of 
 the paste in a weighed centrifuge tube. Add 20 to 30 ce of “ex- 
 traction mixture” (see Reagents), mix thoroughly with a glass rod, 
 wash the rod with more of the extraction mixture, and add enough: 
 
io 
 
 ETO Pe ae ee Sen I ee ee ee 
 
 OUTSIDE WHITE TITANIUM-ZINC PAINT 5 
 
 of the reagent to make a total of 60 cc in the tube. Place the tube 
 in the container of a centrifuge, surround with water, and counter- 
 balance the container of the opposite arm with a similar tube or a 
 tube with water. Whirl at a moderate speed until well settled. De- 
 cant the clear supernatant liquid, repeat the extraction twice with 40 
 cc of extraction mixture and once with 40 cc of ether. 
 
 After drawing off the ether, set the tube in a beaker of water at 
 about 80° C. or on top of a warm oven for 10 minutes, then in an 
 oven at 105 to 110° C. for two hours. Cool, weigh, and calculate 
 the percentage of pigment. Grind the pigment to a fine powder, 
 pass through a No. 80 sieve to remove any skins, and preserve in a 
 stoppered bottle. 
 
 (g) Preparation or Farry Aciwns.—To about 25 g of the paste 
 in a porcelain casserole, add 15 ce of aqueous sodium hydroxide (see 
 Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on 
 a steam bath until saponification is complete (about one hour). Add 
 100 ce of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
 10 ce in excess), boil, stir, and transfer to a separatory funnel to 
 which some water has been previously added. Draw off as much as 
 possible of the acid aqueous layer, wash once with water, then add 
 50 cc of water and 50 cc of ether. Shake very gently with a whirl- 
 ing action to disolve the fatty acids in the ether, but not so vio- 
 lently as to form an emulsion. Draw off the aqueous layer and wash 
 the ether layer with one 15 cc portion of water and then with 5 cc 
 portions of water until free from sulphuric acid. Then draw off the 
 water layer completely. Transfer the ether solution to a dry flask 
 and add 25 to 50 g of anhydrous sodium sulphate. Stopper the 
 flask and let stand with occasional shaking at a temperature below 
 25° ©. until the water is completely removed from the ether solution, 
 which will be shown by the solution becoming perfectly clear above 
 the solid sodium sulphate. Decant this clear solution, if necessary, 
 through a dry filter paper into a dry 100 cc Erlenmeyer flask. Pass 
 a. rapid current of dry air (pass through a CaCl, tower) into the 
 mouth of the Erlenmeyer flask and heat to a temperature below 
 75° ©. on a dry, hot plate until the ether is entirely driven off. 
 
 It is important to follow all of the details, since ether generally 
 contains alcohol, and after washing with water always contains 
 water. It is very difficult to remove water and alcohol by evapora- 
 tion from fatty acids, but the washing of the ether solution and sub- 
 sequent drying with anhydrous sodium sulphate removes both water 
 and alcohol. Ether, in the absence of water and alcohol, is easily 
 removed from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. __ 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (h) Test ror Mrnerat Om ann Orser UNSAPONIFIABLE Mar- 
 TER.—Place 10 drops of the fatty acid (g), in a 50 cc test tube, add 
 5 cc of alcoholic soda (see Reagents), boil vigorously for five min- 
 utes, add 40 cc of water, and mix; a clear solution indicates that 
 not more than traces of unsaponifiable matter are present. If ail 
 solution is not clear, the oil is not pure linseed oil. 
 
 (¢) Ioprne Nita or Farry Actips.—Place a small dannttty of 
 the fatty acids (g) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) into 
 a 500 ce bottle having a well-ground glass stopper, or an Erlen- 
 meyer flask having a specially flanged neck for the iodine test. Re- 
 weigh the burette or beaker and determine the amount of sample 
 used. Add 10 ce of chloroform. Whirl the bottle to dissolve the 
 sample. Add 10 ec chloroform to two empty bottles like that 
 used for the sample. Add to each bottle 25 cc of the Hanus solu- 
 tion (see Reagents) and let stand with occasional shaking’ for one- 
 half hour. Add 10 cc of the 15 per cent potassium iodide solution 
 and 100 ec of water, and titrate with standard sodium thiosulphate, 
 using starch as indicator. The titrations on the two blank tests 
 should agree within 0.1 cc. From the difference between the aver- 
 age of the blank titrations and the titration on the sample and the 
 iodine value of the thiosulphate solution, calculate the iodine number 
 of the sample tested. (Iodine number is centigrams of iodine to 1 g 
 of sample.) If the iodine number is less than 170, the oil does not 
 meet the specification. 
 
 (7) Coarsk Partictrs AND SKINS. Dry in an oven at 105 to 
 110° C. a No. 325 sieve, cool, and weigh accurately. Weigh an 
 amount of semipaste cdmtinibitee! 10 g of pigment (see V, 2, (f), add 
 100 ce of kerosene, mix thoroughly, and wash with kerosene through 
 the sieve, breaking up all lumps, but not grinding. After wash- 
 ing with kerosene until all but the particles too coarse to pass the 
 sieve have been washed through, wash all kerosene from the sieve 
 with ether or petroleum ether, heat the sieve and contents for one 
 hour at 105 to 110° C., cool and weigh. 
 
 3. ANALY RS OF PIGMENT 
 
 (a) QUALITATIVE een —Make qualitative analysis “FolLDeEAY 
 ordinary methods. The pigment should show negative test for sul- 
 phide sulphur and appreciable water-soluble matter; ash a sample of 
 the semipaste or ready-mixed paint and test for ‘aaa? 
 
 (6) Marrer Sotuste In Warer.—Transfer 2.5 g of the pigment 
 to a graduated 250 cc flash, add 100 cc of water, boil for five min- 
 utes, cool, fill to the mark with water, mix, and allow to settle. 
 Pour the supernatant liquid through a dry filter paper and discard 
 
eS 
 
 % 
 { 
 j 
 i: 
 ; 
 > 
 
 4 
 
 | 
 
 OUTSIDE WHITE TITANIUM-ZINC PAINT 7 
 
 the first 20 cc. Then evaporate 100 cc of the clear filtrate to dry- 
 ness in a weighed dish, heat for one hour at 105 to 110° C., cool and 
 weigh. 
 
 (¢) Trranrom Oxmr—wWeigh accurately about 1 g of the pig- 
 ment, transfer to a 250 cc Pyrex beaker, add 25 cc of concentrated 
 sulphuric acid and 8 g of ammonium sulphate. Mix well and heat 
 on a hot plate until fumes of sulphuric acid are evolved, and then 
 
 ‘ continue the heating over a strong flame until solution is complete 
 
 (usually not over five minutes of boiling) or it is apparent that the 
 residue is composed of silica or siliceous matter. Caution should 
 be observed in handling this hot acid solution. Cool the solution, 
 dilute with 100 cc of water, stir, heat carefully to boiling while 
 stirring, settle, filter through paper and transfer the precipitate com- 
 pletely to the paper. Wash the insoluble residue with cold 5 per cent 
 (by volume) sulphuric acid until titanium is removed. 
 
 Dilute the filtrate to 200 cc and add about 30 cc of ammonia, 
 specific gravity 0.90, to lower the acidity to approximately 5 per 
 cent sulphuric acid (by volume). 
 
 Wash out a Jones reductor’? with dilute 5 per cent (by Ponttiey 
 sulphuric acid and water, leaving sufficient water in the reductor to 
 fill to the upper level of the zinc. (These washings should require 
 not more than one or two drops of 0.1 WV potassium permatganate 
 solution to obtain the pink color.) Empty the receiver, and put in 
 it 25 cc (measured in a graduate) of ferric sulphate solution. (See 
 
 Reagents.) Reduce the prepared titanium solution as follows: (1) 
 
 Run 50 ce of the 5 per cent sulphuric acid solution through the 
 reductor at a speed of about 100 cc per minute, (2) follow this with 
 the titanium solution, (3) wash out with 100 cc of 5 per cent sul- 
 phuric acid, (4) finally run through about 100 ce of water. 
 
 Care should be observed that the reductor is always filled with 
 solution or water to the upper level of the zinc. 
 
 Gradually release the suction, wash thoroughly the glass tube that 
 was immersed in the ferric sulphate solution, remove the receiver, 
 and titrate immediaely with 0.1 V potassium permanganate solution. 
 (See Reagents.) 
 
 tec 0.1 V KMn0,=0.00481 g Ti=0.00801 ¢ TiO, 
 
 Run a blank determination, using the same reagents, washing the 
 reducer as in the above determination. Subtract this permanganate 
 reading from the original reading and calculate the final reading to 
 titanium dioxide (TiO,) (which will include iron, chromium, 
 arsenic, and any other susbtance which is reduced by zine and acid). 
 
 2 Directions for preparing a Jones reductor may be found in Blair, The Chemical 
 Analysis of Iron, 8th ed., Lippincott & Co., or Treadwell-Hall, Analytical Chemistry, 5th 
 ed., J. Wiley & Sons, p. 368. 
 
8 CIRCULAR OF THE BUREAU .OF STANDARDS 
 
 (7d) Bartum SuipHate.—Ignite and weigh the insoluble matter 
 obtained in separating the titanium (see V, 3, (c)). Mix the ignited 
 residue with about 10 times its weight of anhydrous sodium car- 
 bonate (grind the mixture in an agate mortar if necessary), fuse the 
 mixture in a covered platinum crucible, heating about one hour. 
 Let cool, place the crucible and cover in a 250 cc beaker, add about 
 100 ce re water, and heat until the melt is disintegrated. Filter on 
 paper (leaving the crucible and cover in the beaker) and wash the 
 beaker and filter thoroughly with hot water to remove soluble sul- 
 phates. Place the beaker containing the crucible and cover under 
 the funnel, pierce the filter with a glass rod, and wash the carbonate 
 residue into the beaker by means of a jet of hot water. Wash the 
 paper with hot dilute hydrochloric acid (1:1), and then with hot 
 water. If the carbonate residue is not completely dissolved, add 
 sufficient dilute hydrochloric acid to effect solution, and remove the 
 crucible and cover, washing them with a jet of water. Heat the 
 
 solution to boiling and add 10 to 15 cc of dilute sulphuric acid, and — 
 
 continue the boiling for 10 or 15 minutes longer. Let the precipitate 
 settle, filter on a weighed Gooch crucible, wash with hot water, 
 ignite, cool, and weigh as BaSO,. Subtract the result from the 
 original nate nhs to obtain the siliceous material. 
 
 (2) Zinc Oxipz.—Weigh accurately about 0.5 g of the aoe 
 transfer to a 400 ce beaker, add 30 cc of hydrochloric acid (1: 2), 
 boil for two or three minutes, add 200 ce of water and a small piece 
 
 of litmus paper; add strong ammonia until slightly alkaline, render 
 
 just acid with hydrochloric acid, then add 38 ce of strong hydro- 
 chloric acid, heat nearly to boiling, and titrate with standard ferro- 
 cyanide as in standardizing that solution (see Reagents). Calculate 
 total zinc as zinc oxide. Las 
 
 (f) CatcuLations.—In case the percentage of barium sulphate 
 (V, 8, (d@)) is not more than 3.17 times as great as the percentage 
 of titanium oxide (V, 3, (¢)), add the two together and call the sum 
 the percentage of titanium pigment. If the percentage of barium 
 sulphate is greater than this amount, take 3.17 times the percentage 
 of titanium oxide as the percentage of barium sulphate to be included 
 in the percentage of titanium pigment and include the remainder 
 in the percentage of extending pigments. Subtract the sum of the 
 percentages of titanium pigment, zinc oxide (V, 3, (¢)), and matter 
 soluble in water (V, 8, (6)) from 100. Call the remainder percent- 
 age of extending pigments. 
 
 4. LABORATORY EXAMINATION, READY-MIXED PAINT 
 
 (a) Caxine In Conratner.—Follow the procedure outlined in 
 V, 2, (a), noting that the paint should be no more difficult to break 
 up edie a good grade of mixed paint. 
 
 # 
 
OUTSIDE WHITE TITANIUM-ZINC PAINT 9 
 
 (b) Wetcur per Garton.—Weigh a clean, dry, 100 cc graduated 
 flask. Fill to the mark with the thoroughly mixed paint and weigh 
 again. The increase in weight expressed in grams divided by 100 
 gives the specific gravity, which multiplied by 8.33 gives the weight 
 in pounds per gallon. 
 
 (c) Brusaine Properties anp Timz or Dryine.—Brush this well- 
 mixed paint on a clean tin plate panel. Note whether the paint 
 works satisfactorily under the brush. Place the panel in a vertical 
 position in a well-ventilated room and let stand for 18 hours. The 
 paint should be dry and free from streaks. Flow a portion of the 
 paint on a clean glass plate. Let dry in a nearly vertical position at 
 room temperature: (65 to 100° F.). The film shall show no streak- 
 ing or separation within a distance of 4 inches from the top. 
 
 (d) Restsrance to SunpHine Fumes.—Apply a suflicient number 
 of coats of the paint to two glass plates to completely hide the sur- 
 face, and expose one of the plates in a saturated atmosphere of 
 hydrogen sulphide for 18 hours. Compare the color with the un- 
 exposed plate. The exposed plate should be practically no darker 
 than the unexposed one. There shall be no greater difference in the 
 color of the two plates than there will be with similar plates coated 
 with a paint made with titanium pigment, lead free zinc oxide, and 
 raw or refined linseed oil with sufficient cobalt added for drying. 
 
 (e) Cotor.—Paint the sample and the standard on clean metal or 
 glass, so that the edges touch one another. Let dry and compare 
 colors. ) 
 
 ) Warer.—Mix 100 g of the paint in a 250 or 300 ce flask with 
 “5 cc of toluol. Connect with a condenser and distill until about 
 50 cc of distillate has been collected in a graduate. The temperature 
 in the flask should be then about 105 to 110° C. The number of 
 cubic centimeters of water collecting under the toluol in the receiver 
 is the percentage of water in the paint. 
 
 4g) Voratin Tainner.—Follow the procedure outlined in V, 2, 
 (e). Correct the result for any water found (see V, 4, (f)), and 
 report the remainder as volatile thinner. 
 
 (h) Percentace or Picment.—Follow the procedure outlined in 
 V, 2, (f). 
 
 , (4) Txstrxc NonvoaTILe Venicie.—Follow the procedure out- 
 
 "lined in V, 2, (g), (4), and (é), except that in the preparation of 
 the fatty acids the mixture of paint and alkali is heated on the steam 
 bath until all volatile thinner is driven off. 
 
 (j) Coarse ParTICLEs AND Sxrns.—Follow the procedure outlined 
 in V, 2, (7). | , : 
 
 (k) TEstTINe Picment.—Follow the procedure outlined in V, 3, 
 (a) to (f), inclusive. 
 
10 CIRCULAR OF THE BUREAU OF STANDARDS 
 5. REAGENTS 
 
 (a) Uranyt Inprcator.—A 5 per cent solution of uranyl nitrate in 
 water or a 5 per cent solution of uranyl acetate in water made 
 slightly acid with acetic acid. 
 
 (6) Sranparp Porasstum Frrrocyaniws.—Dissolve 22 g of the 
 pure salt in water and dilute to 1,000 cc. To standardize transfer 
 about 0.2 g (accurately weighed) of pure metallic zine or freshly 
 ignited pure zinc oxide to a 400 cc beaker. Dissolve in 10 ce of 
 hydrochloric acid and 20 cc of water. Drop in a small piece of 
 litmus paper, add ammonium hydroxide until slightly alkaline, 
 then add hydrochloric acid until just acid, and then 38 cc of strong 
 hydrochloric acid. Dilute to about 250 ce with hot water and heat 
 nearly to boiling. Run in the ferrocyanide solution slowly from a 
 burette with constant stirring until a drop tested on a white porce- 
 lain plate with’a drop of the uranyl indicator shows a brown tinge 
 after standing one minute. A blank should be run with the same 
 amounts of reagents and water as in the standardization and in 
 titration of the sample. The standardization must be under the 
 same conditions of temperature, volume, and acidity as obtained 
 when the sample is titrated. 
 
 (c) Sranparp Soprum. TurosutpHatTe SoLutron iD niles pure 
 sodium thiosulphate in distilled water (that has been well boiled 
 to free it from carbon dioxide) in the proportion of 24.83 g of 
 crystallized sodium thiosulphate to 1,000 cc of the solution. It 
 is best to let this solution stand for about two weeks before stand- 
 ardizing. Standardize with pure resublimed iodine. This Solution 
 will be approximately decinormal and it is best to leave it as it is 
 after determining its exact iodine value, rather than to attempt to 
 adjust it to exactly decinormal. Preserve in a stock bottle Aravieg 
 with a guard tube filled with soda lime. 
 
 (zd) Srarcu Sorutrion.—Stir up 3 g of potato Hine or 8 é of 
 soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
 300 to 400 ec.of boiling water, and boil the mixture until the starch 
 is practically dissolved, then dilute to 1 liter. Sore 
 
 (e) Extraction Miieeeien — 
 
 10 volumes ether (ethyl ether). | We 
 6 volumes benzol. , ee 
 4 volumes methyl alcohol. 
 1 volume acetone. 
 
 eae 
 ait 
 
 (f) Aqueous Soprum Hyproxinz.—Dissolve 100 g of. sodium 
 
 hydroxide in distilled water and dilute to 300 ce. 
 (7g) Porassrum Iopipz Sonurion.—Dissolve 150 g of. otassium 
 iodide free from iodate in distilled water and dilute to 1,00 ce, 
 
 2 Treadwell-Hall, Analytical Chemistry, 2, 6th ed., p. 551. 
 
| 
 : 
 
 OUTSIDE WHITE TITANIUM-ZINC PAINT 11 
 
 (h) Hanus Sorution.—Dissolve 13.2 g of iodine in 1,000 cc of 
 99.5 per cent glacial acetic acid, which will not reduce chromic acid. 
 Add enough bromine to double the halogen content, determined 
 by titration (3 cc of bromine is about the proper amount). The 
 iodine may be dissolved by the aid of heat, but the solution should 
 be cold when the bromine is added. 
 
 (4) Auconoric Soprom Hyproxme Soxiurion.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant the 
 clear liquid into another bottle and keep well stoppered. This solu- 
 tion should be colorless or only slightly yellow when used, and it will 
 keep colorless longer if the alcohol is previously treated with sodium 
 hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 15 days, 
 and then distilled. 
 
 (7) 0.1 NV Porasstom Prermaneanate Sotution.—Dissolve 3.161 
 g of pure potassium permanganate in a liter of distilled water, let 
 stand 8 to 14 days, siphon off the clear solution (or filter through an 
 asbestos filter), and standardize as follows: In a 400 cc beaker dis- 
 solve 0.25 to 0.30 g of Bureau of Standards sodium oxalate in 250 
 ce of hot water (80 to 90° C.) and add 15 cc of dilute sulphuric acid 
 (1:1). Titrate at once with the potassium permanganate solution, 
 stirring the liquid vigorously and continuously. The permanganate 
 must not be added more rapidly than 10 to 15 cc per minute, and the 
 last 0.5 to 1 cc must be added dropwise with particular care to allow 
 each drop to be fully decolorized before the next is introduced. The 
 solution should not be below 60°. C. by the time the end point is 
 reached. (More rapid cooling may be prevented by allowing the 
 beaker to stand on a small asbestos covered hot plate during the 
 titration. The use of a small thermometer as a stirring rod is most 
 convenient.) The weight of sodium oxalate used multiplied by 
 0.8334 gives its iron equivalent, or multiplied. by 1.1954 gives its 
 titanium dioxide (TiO,) equivalent.’ 
 
 The permanganate solution should be kept in a glass-stoppered 
 bottle painted black to keep out light. 
 
 (%) Ferric Sutenate Sonurion.—A solution containing 2 per 
 cent of iron as ferric sulphate is desired and may be prepared as 
 follows: Dissolve 20 g of pure iron or plain carbon steel in a slight 
 excess of hydrochloric acid, oxidize with nitric acid, heat with about 
 80 cc of sulphuric acid until fumes are evolved, finally cool, and 
 dilute to 1,000 ce set on steam bath, until dissolved, and filter if 
 necessary. Add 0.1 V permanganate solution until a faint pink color 
 shows that any ferrous iron has been oxidized. Ferric ammonium 
 sulphate may also be used.‘ 
 
 SESS ERE TS RG al ees En ee oe Ome a 
 ‘ sInternational Atomic Weights, 1925. 
 «Gooch, Methods in Chemical Analysis, 1st ed., p. 426. 
 
12 ! CIRCULAR OF THE BUREAU OF STANDARDS 
 VI. PACKING AND MARKING 
 No details specified. ) 
 VII ADDITIONAL INFORMATION 
 
 This specification covers the requirements for a high-grade white 
 paint for outside and general use, intended particularly to be used 
 wherever excessive amounts of sulphide fumes would quickly discolor 
 the average outside white paint. For marine use, the addition of 
 1 pint of water-resisting spar varnish to each gallon of paint, just 
 before application, is recommended. It may be ordered either in 
 the form of semipaste pigment ground in linseed oil or of ready- 
 mixed paint, and the purchaser shall state which is desired. 
 
 The semipaste shall be purchased by net weight, and the ready- 
 mixed paint either by weight or volume (231 cubic inches to the 
 gallon). : 
 
 VIII. GENERAL SPECIFICATIONS 
 
 No details specified. 
 
 ee 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C, 
 AT 
 5 CENTS PER OOPY 
 
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 : 
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 U. S. Gov’t 
 Master 
 Specification 
 No. 283 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 216 
 
 [Issued May 9, 1925] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 | PUTTY 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 283 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on May 8, 1925, for the use of the Departments and Independent 
 Establishments of the Government in the purchase of putty. 
 
 CONTENTS 
 
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 Septsrreseereras Speciiications.2 oo ae ei i es 
 
 I. CLASSES 
 
 OOMmMNAAWwWAWANHNNNWNN FE 
 
 The putty shall be of two classes—either whiting putty or white 
 lead-whiting putty, as called for in the proposal. 
 
 II. MATERIAL 
 
 No details specified. 
 43782°—25 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 III. GENERAL REQUIREMENTS 
 No details specified. 
 IV. pHa REQUIREMENTS 
 
 1. PIGMENT 
 
 The pigment in whiting putty shall consist of finely powdered 
 natural chalk of high-grade quality, with the minimum amount of 
 pure tinting colors to produce the desired colors. It shall be free 
 from grit, shall be practically neutral, shall possess the property of 
 mixing with linseed oil to form good putty, and shall have the 
 structure and other physical characteristics of the best natural 
 whiting suitable for putty making. The total pigment shall con- 
 tain not less than 95 per cent of calcium carbonate. 
 
 The pigment in white lead-whiting putty shall contain not less 
 than 10 per cent of white lead (basic carbonate orsbasie sulphate), a 
 minimum amount of pure tinting colors if necessary, the remainder 
 to be the above-described halewhat whiting. The sum‘ of the whi te 
 lead and calcium carbonate in the total pigment. shall be not less 
 than 95 per cent. 
 
 ' 2, LIQUID 
 
 The liquid in either class shall be entirely pure raw linseed oil. 
 3. PUTTY een 
 
 The putty shall be made by thoroughly erin diae” the anne Sides 
 of dry pigment with pure raw linseed oil to a doughlike paste of 
 proper putty consistency that shall be smooth, uniform, and suitable, 
 as received, for glazing purposes. The -putty as-received shall not 
 be caked in the container. It shall possess the characteristic prop- 
 erties of and shall be equal to the best grade of putty. The color 
 when specified shall match a sample mutually aia MBOR by buyer 
 and seller. 8 
 
 The putty shall consist of: iat ae ythioat 28 
 
 Ingredients 
 
 Plement nono 2 bad an Resear a eS oe em ae oe ee ee 
 rear linseed 0 
 
 eee eet th ok eT ee ee 
 eee ee ee ee ee 
 
 Ol ee ee ee ee 
 
 eR EE ERE EE Re 
 
ee ee es Se ee Ea 
 
 SPECIFICATION FOR PUTTY 3 
 V. METHODS FOR SAMPLING AND TESTING 
 
 Deliveries will, in general, be sampled and tested by the follow- 
 ng methods, but the purchaser reserves the right to use any addi- 
 tional available information to ascertain whether the material meets 
 the specification. 
 
 1, SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. Whenever possible, an original un- 
 opened container shall be sent to the laboratory, and when this is 
 for any reason not done the inspector shall determine by kneading 
 with his hand whether the material has the consistency of good 
 putty. He shall then thoroughly mix the contents of the container 
 and draw a sample of not less than 1 pound of the thoroughly 
 mixed putty, place it in a clean, dry metal or glass container, which 
 
 must be filled with the sample, closed with a tight cover, sealed, 
 
 marked, and sent to the laboratory for test with the inspector’s re- 
 port on caking in container. 
 
 When requested, a duplicate sample may be taken from the same 
 package and delivered to the seller, and the inspector may take a 
 third sample to hold for test in case of dispute. 
 
 z. LABORATORY EXAMINATION 
 
 (a) Cawxinc In Contarner.—When an original package is re- 
 ceived in the laboratory, it shall be weighed, opened, and mixed 
 with a stiff spatula or paddle. The putty must be no more difficult 
 to mix and knead with the hand than a normal good grade of putty. 
 The putty shall finally be thoroughly mixed, removed from the con- 
 tainer, and the container wiped clean and weighed. This weight 
 subtracted from the weight of the original package gives the net 
 weight of the contents. A portion of thoroughly mixed putty shall 
 be placed in a clean container and the portions for the remaining 
 
 tests promptly weighed out. 
 
 _(b) Moisture anp Orner Vouatite Marrer.—Weigh accurately 
 from 8 to 5 g of the putty in a tared flat-bottomed dish about 8 cm 
 in diameter, spreading the putty over the bottom. Heat at 105 to 
 
 110° C. for three hours, cool, and weigh. Calculate the loss in 
 
 weight as the percentage of moisture and volatile matter. 
 
 (c) Frnspom From Lumps or Grit.—Spread a portion of the 
 mixed putty on a clean piece of glass, noting the presence of any 
 lumps. Thin about 5g of the putty with 3 or 4 cc of raw linseed oil 
 or turpentine, spread the mixture to thin films on the glass, using a 
 wide spatula or putty knife and note the presence of grit. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (d) Worxine Quatrrres—Work up about 10 g of the mixed 
 putty in the hands, noting its tendency to stick. Apply a portion 
 of the putty to the edge of a clean piece of glass, metal, or well- 
 filled wood and work it out to a smooth bevel with a spatula or 
 putty knife. Spread another portion to very thin films on the glass. 
 The putty in both tests shall show good adhesive and elastic prop- 
 erties and shall not be “short” or “mealy.” For comparison pur- 
 poses a small batch of good putty can be satisfactorily made by tak- 
 ing 20 g of dry, fine natural whiting of known quality, adding about 
 4 cc of raw linseed oil, and thoroughly kneading to a stiff dough 
 by hand. : 
 
 (c) Percentace or Picment.—Weigh accurately about 15 g of 
 the putty in a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
 traction mixture” (see Reagents), mix thoroughly with a glass rod, 
 wash the rod with more of the extraction mixture, and add enough of 
 the reagent to make a total of 60 cc in the tube. Place the tube in 
 the container of a centrifuge, surround with water, and counterbal- 
 ance the container of the opposite arm with a similar tube or a tube 
 with water. Whirl at a moderate speed until well settled. Decant 
 the clear supernatant liquid, repeat the extraction twice with 40 cc 
 of extraction mixture and once with 40 cc of ether. After drawing 
 off the ether set the tube in a beaker of water at about 80° C. or on 
 top of a warm oven for 10 minutes, then in an oven at 105 to 110° 
 C. for two hours. Cool, weigh, and calculate the percentage of pig- 
 ment. Grind the pigment to a fine powder, pass through a No. 80 
 sieve to remove any skins, and preserve in a stoppered bottle. 
 
 (f) Preparation or Farry Acrps.—To about 25 g of the putty 
 in a porcelain casserole add 15 cc of aqueous sodium hydroxide (see 
 Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on a 
 ‘steam bath until saponification is complete (about one hour). 
 
 Add 100 cc of water, boil, add sulphuric acid of specific gravity 
 1.2 (8 to 10 ce in excess), boil, stir, and transfer to a separatory 
 funnel to which some water has been previously added. Draw off 
 as much as possible of the acid aqueous layer, wash once with water, 
 than add 50 cc of water and 50 ce of ether. Shake very gently with 
 a whirling action to dissolve the fatty acids in the ether, but not 
 so violently as to form an emulsion. Draw off the aqueous layer and 
 ‘wash the ether layer with one 15 cc portion of water and then 
 with 5 cc portions of water until free from sulphuric acid. Then 
 draw off the water layer completely. Transfer the ether solution 
 to a dry flask and add 25 to 50 g of anhydrous sodium sulphate. 
 Stopper the flask and let stand with occasional shaking at a tem- 
 perature below 25° ©. until the water is completely removed from 
 the ether solution, which will be shown by the solution becoming 
 perfectly clear above the solid sodium sulphate. Decant this clear 
 
SPECIFICATION FOR PUTTY 5 
 
 solution, if necessary, through a dry filter paper into a dry 100 cc 
 Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
 CaCl, tower) into the mouth of the Erlenmeyer flask and heat to 
 a temperature below 75° C. on a dry, hot plate until the ether is 
 entirely driven off. 
 
 It is umportant to follow all of the details, since ether generally 
 contams alcohol, and after washing with water always contains 
 water. It is very difficult to remove water and alcohol by evapora- 
 tion from fatiy acids, but the washing of the ether solution and 
 subsequent drying with anhydrous sodium sulphate removes both 
 water and alcohol. Ether, in the absence of water and alcohol, is 
 easily removed from fatty acids by gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (g) Test ror Minerat Om ann Orner UNsaronrri1asLte Mar- 
 TER.—Place 10 drops of the fatty acid (f) in a 50 cc test tube, add 
 5 ce of alcoholic soda (see Reagents), boil vigorously for five min- 
 utes, add 40 cc of water, and mix; a clear solution indicates that 
 not more than traces of unsaponifiable matter are present. If the 
 solution is not clear, the oil is not pure linseed oil. 
 
 (A) Iopine Nace or Farry Acips.—Place a small quantity of 
 the fatty acids (/) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
 into a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
 meyer flask having a specially flanged neck for the iodine test. 
 Reweigh the burette or beaker and determine the amount of sample 
 used. Add 10 cc of chloroform. Whirl the bottle to dissolve the 
 sample. Add 10 ce of chloroform to two empty bottles like that 
 used for the sample. Add to each bottle 25 cc of the Hanus solution 
 (see Reagents) and let stand with occasional shaking for one-half 
 hour. 
 
 Add 10 ce of the 15 per cent potassium iodide solution and 100 ce 
 of water and titrate with standard sodium thiosulphate, using starch 
 as an indicator. The titrations on the two blank tests shonld agree 
 within 0.1 cc. From the difference between the average of the blank 
 titrations and the titration on the sample and the iodine value of 
 the thiosulphate solution calculate the iodine number of the sample 
 tested. (Iodine number is centigrams of iodine to 1 g of sample.) 
 If the iodine number is less than 170, the oil does not meet the 
 specification. 
 
 (z) Coarsz Partictes anp Sxrns.—Dry in an oven at 105 to 
 110° C. a No. 325 sieve, cool and weigh accurately. Weigh an 
 amount of putty containing 10 g of pigment (see V, 2, (e)), add 
 100 cc of kerosene, mix thoroughly, and wash with kerosene through 
 the sieve, breaking up all the lumps but not grinding. After wash- 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 ing with kerosene until all but the particles too coarse to pass the 
 sieve have been washed through wash all kerosene from the sieve 
 with ether or petroleum ether, heat the sieve and contents for one 
 hour at 105 to 110° C., cool and weigh. | 
 
 3. ANALYSIS OF PIGMENT 
 
 (a) Quatrrative Anatysts.—Make qualitative analysis following 
 ordinary methods. 
 
 (b) Reaction anp Frre Arxari.—Boil 2 g of the pigment for 
 five minutes with 100 cc of water, filter and to the clear filtrate add 
 two drops of phenolphthalein and titrate while hot with 01 N 
 hydrochloric acid. Not over 0.2 ce of 0.1 V HCl shall be required 
 to destroy the red color. The filtrate shall also be neutral to methyl 
 orange indicator. | : | 
 
 (c) Srrvcorurr.—Compare the structure of the pigment under the 
 microscope with a known specimen of natural (chalk) whiting (with 
 or without the addition of white lead). | . 
 
 (d) Cauctum CarBoNATE (IN THE ABSENCE OF WHITE LEAD) .— 
 Weigh accurately 0.25 g of the dry pigment, transfer to a 250 ce 
 beaker, moisten with alcohol, dissolve in about 20 ec of 1: 1 hydro- 
 chloric acid, keeping the beaker covered. Digest for 10 minutes on 
 the steam bath, dilute to about 150 ce, then filter the solution and 
 wash the insoluble residue with hot water. Bring to near boiling 
 and make alkaline with ammonia after adding a few ce of bromine 
 water. Let the precipitate settle, filter, and wash thoroughly with 
 hot water. Take the filtrate and washings from the iron, aluminum, 
 etc., concentrate to about 200 cc, adding a few drops of ammonia. 
 Boil and add while boiling 10 to 15 ce of a hot saturated solution of 
 ammonium oxalate, stir, and continue the boiling until the precipi- 
 tated calcium oxalate becomes granular. Set on steam bath to settle 
 (about one hour). Filter and wash the oxalate thoroughly with 
 small amounts of hot water. Transfer the moist precipitate to a 400 
 ce beaker by means of a stream of water from the wash bottle, dis- 
 solve the part remaining on the filter by washing with warm dilute 
 sulphuric acid. Add to the beaker 20 ce of sulphuric acid (1: 1), 
 dilute to about 300 cc with hot water, and titrate the oxalic acid 
 with 0.1 VY potassium permanganate and report as CaCQ,.* 
 
 =0.0028 g CaO 
 1 cc 0.1 V KMnO; = 9 9950 z GaCO,. | 
 
 (ec) Wutre Leap anp Catcrum Carronate.—Weigh accurately 1 ¢ 
 of the dry pigment into a 250 cc beaker, moisten with a few drops 
 of alcohol, add slowly 25 to 30 e¢ of concentrated hydrochloric acid, 
 
 11f the sample is impure, reference should be made to the methods as given in The 
 Analysis of Silicate and Carbonate Rocks, by W. F. Hillebrand, United States Geological 
 Survey Bulletin No. 700. ; 
 
SPECIFICATION FOR PUTTY 1a 
 
 cover, and boil for 5 to 10 minutes. Dilute to about 150 ce with hot 
 water and heat for about 15 minutes, let settle on the steam bath, 
 filter while hot, and wash any insoluble residue thoroughly with hot 
 water. (Avoid allowing the filter paper to become cold.) Make 
 the solution just alkaline with ammonia, then just faintly acid to 
 litmus, using dilute (1:10) hydrochloric acid. Dilute to about 300 ce 
 and pass hydrogen sulphide gas into the clear solution to complete 
 precipitation. Settle, filter on paper, and wash with water contain- 
 ing some hydrogen sulphide, dissolve the sulphide in hot nitric acid 
 (1:3), add 5 to 10 cc of dilute sulphuric acid (1:1), evaporate until 
 copious fumes of sulphuric anhydride are evolved, cool, add about 
 75 ec of water, and then about 75 cc of 95 per cent ethyl alcohol. 
 Stir, let settle, filter on a weighed Gooch crucible, wash with dilute 
 alcohol, dry, gently ignite, and weigh as lead sulphate. In the 
 absence of sulphates multiply this weight by the factor 0.854 and 
 report the result as basic carbonate white lead. In the presence of 
 sulphates the weight of lead sulphate multiplied by the factor 0.883 
 shall be considered white lead. (It is not possible to determine the 
 amount of lead carbonate and lead sulphate when carbonates or sul- 
 phates of calcium are present. The arbitrary factor 0.883 is the 
 mean of the largest and smallest of the three factors to convert 
 PbSO, to (PbCO,),Pb(OH),, to PbSO,PbO, and to (PbSOz),PbO.) 
 
 Boil the filtrate from the sulphide separation to expel hydrogen 
 sulphide, add a few drops of nitric acid, and if necessary some ammo- 
 nium chloride, make alkaline with ammonia, settle, and filter off 
 any precipitate of aluminum, iron, etc., and wash the precipitate 
 with hot water. Proceed to determine total calcium as in V, 3, (d), 
 and report as calcium carbonate.’ 
 
 4. REAGENTS 
 
 (az) Sranparp Soprom THIOsULPHATE Sorutrion.—Dissolve pure 
 sodium thiosulphate in distilled water (that has been well boiled 
 to free it from carbon dioxide) in the proportion of 24.83 g of 
 erystallized sodium thiosulphate to 1,000 ce of the solution. It is 
 best to let this solution stand for about two weeks before standardiz- 
 ing. Standardize with pure resublimed iodine.? This solution will 
 be approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value rather than to attempt to adjust 
 it to exactly decinormal. Preserve in a stock bottle provided with 
 
 a guard tube filled with soda lime. 
 
 (b) Srarca Sorution.—Stir up 2 to 3 g of potato starch or 5 g 
 of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
 
 2See footnote 1, p. 6. 
 See Treadwell-Hall, Analytical Chemistry, 2, 6th ed., p. 551. 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 add 300 to 400 cc of boiling water, and boil the mixture until the 
 starch is practically dissolved, then dilute to 1 liter. 
 
 (c) Exrraction Mrixrurr.—10 volumes ether (ethyl ether), 6 vol- 
 umes benzol, 4 volumes methyl alcohol, 1 volume acetone. 
 
 (d@) Aqurous Soprom Hyproxipe.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 ce. 
 
 (¢) Porasstum Iopmwr SoLutrion.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 ce. 
 
 (f) Hanus Soturion.—Dissolve 13.2 g of iodine in 1,000 cc of 
 99.5 per cent glacial acetic acid which will not reduce chromic acid. 
 Add enough bromine to double the halogen content determined by 
 titration (3 cc of bromine is about the proper amount). The iodine 
 may be dissolved by the aid of heat, but the solution should be cold 
 when the bromine is added. 
 
 (g) Axuconotic Soprum Hyproxmwwr Sonurion —Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 about 22 g per 1,000 cc. . Let stand in a stoppered bottle. Decant the 
 clear liquid into another bottle and keep well stoppered. This solu- 
 tion should be colorless or only slightly yellow when used, and it 
 will keep colorless longer if the alcohol is previously treated with 
 sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
 15 days, and then distilled. 
 
 (A) 0.1 NV Porasstum Permancanate Soiurion.—Dissolve 3.161 
 
 g of pure potassium permanganate in a liter of distilled water, let 
 _ stand 8 to 14 days, siphon off the clear solution (or filter through an 
 asbestos filter), and standardize as follows: In a 400 ce beaker 
 dissolve 0.25 to 0.30 g of Bureau of Standards’ sodium oxalate in 
 250 cc of hot water (80 to 90° C.) and add 15 ce of dilute sul- 
 phuric acid (1:1). Titrate at once with the potassium perman- 
 ganate solution, stirring the liquid vigorously and continuously. The 
 permanganate must not be added more rapidly than 10 to 15 ce per 
 minute, and the last 0.5 to 1 cc must be added dropwise, with par- 
 ticular care to allow each drop to be fully decolorized before the 
 next is introduced. The solution should not be below 60° C. by the 
 time the end point is reached. (More rapid cooling may be pre- 
 vented by allowing the beaker to stand on a small asbestos-covered 
 hot plate during the titration. The use of a small thermometer as 
 a stirring rod is most convenient.) The weight of sodium oxalate 
 used multiplied by 0.7469 gives its CaCO, equivalent. 
 
 VI. PACKING AND MARKING 
 
 No details specified. 
 
SPECIFICATION FOR PUTTY g 
 VII. ADDITIONAL INFORMATION 
 
 This specification covers the requirements for a high-grade pre- 
 pared putty for general use. It shall be purchased by net weight. 
 
 VIII. GENERAL SPECIFICATIONS 
 No details specified. 
 
 ) ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D, C. 
 AT 
 5& CENTS PER COPY 
 
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 VII. Packing and Re Ot. Sa noe dn ek eee oe ann oe 
 
 U. S. Gov’t 
 Master 
 Specification 
 No. 375 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 302 
 
 [Issued February 9, 1926] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 SHELLAC, FLAKE ORANGE 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 375 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on January 25, 1926, for the use of the departments and independent 
 establishments of the Government in the purchase of shellac, flake orange. 
 [The latest date on which the technical requirements of this specification shall become mandatory for all 
 
 departments and independent establishments of the Government is April 26, 1926. They may be put 
 into effect, however, at any earlier date, after promulgation.] 
 
 CONTENTS 
 
 Ty wacoeral veguirements) 2) Jou lo ke ie lll UL 
 Vo Detail:requirementsxiisc- 2 .- 22s -24-5- in - 2 6ee-4e-ss es 
 VI. Methods of sampling and testing------------------------------- 
 
 OOrnwwnds OK Ke 
 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification. 
 II. TYPES 
 
 Orange shellac shall be furnished in one of the four types as follows: 
 A, B, C, or D. 
 Il. MATERIAL 
 
 Orange shellac shall be the manufactured product of stick lac (the 
 secretion of the Tacchardia Lacca) freed from most of the lac dye 
 and prepared in flake form. Seed, garnet, and button lac are not 
 admissible under this specification. 
 
 79613°—26 1 
 
= CIRCULAR OF THE BUREAU OF STANDARDS 
 
 IV. GENERAL REQUIREMENTS 
 
 Unless specifically waived in the contract, flake orange shellac 
 must be “free”; that is, any flakes that may have stuck topetas 
 must separate readily under-hand. pressure. 
 
 Fa "? 
 “ 
 ~ 
 
 € 
 
 V. DETAIL REQUIREMENTS 
 
 Flake orange shellac shall conform to the requirements for the 
 respective types given below: 
 
 Color when specified shall be no. darker than a, sample mutually 
 agreed upon by the buyer and seller when tested § as per aay VI 
 
 2 (g). 
 VI. METHODS OF SAMPLING AND. TESTING ids 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional avarl- 
 able information to ascertain whether the material meets the specification. 
 
 1. Samptrne.—It is mutually agreed by the buyer and seller that 
 double handfuls shall be taken from 10 per cent of the packages 
 taken at random from the delivery. The composite samples taken 
 as above shall be thoroughly mixed, quartered down to approxi- 
 mately 3 pounds and divided into bres equal portions which shall 
 be separately sealed and marked. The inspector shall send one of 
 the sealed samples to the testing laboratory, retam one for umpire 
 test in case of dispute, and, if requested, shall deliver the third to the 
 seller. 
 
 2. LABoRATORY ExamINaTIoN.—Thoroughly mix the sample of 
 shellac to be tested.and grind not less, than a 100 g portion to entirely 
 pass a 20-mesh screen and keep in a tightly stoppered container. 
 Make the necessary detente aana:t on ae mia with as little 
 delay as possible: . : 
 
 (a) Lodine number. sinirodnes 0. 2 “of ‘chee "ticlloa an a 
 250 cc dry bottle of clear-glass with a ground-glass stopper, add 20 
 cc of glacial acetic acid (see Reagents) and warm the mixture gently 
 
 on top of a hot-water bath until solution. is. complete, (except for the 
 wax). A pure shellacis rather difficultly soluble; solution is quicker 
 according to the proportion of rosin, present... Add.10 cc of chloro- 
 form (see Reagents) and cool the solution to 21.5 to 22.5° C. The 
 
ee a ee ean SS ee 
 
 a = 
 
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 SPECIFICATION FOR FLAKE ORANGE SHELLAC 3 
 
 bottles should be allowed to stand half immersed in‘a shallow pan 
 of water, well insulated or equipped with a suitable thermostat, at 
 least 30 minutes at 21.5 to 22.5° C. before the Wijs solution nS 
 Reagents) is added. Add 20 ce of Wijs solution (which shall be at 
 a temperature of 21.5 to 22.5° C.) from a pipette, having a rather 
 small delivery aperture (about 30 seconds). Close the bottle, place 
 it back into the pan of water, and note the time. The bottles must 
 be kept half immersed in water at 21.5 to 22.5° C. during the one 
 hour that the shellac is exposed to the Wijs solution. Agitate the 
 bottles occasionally during that hour. 
 
 _ Note.—If a number of samples are being run, at least five minutes should be 
 allowed between additions of the Wijs solution. 
 
 After exactly one hour add 10 ce of freshly prepared 10 per cent 
 potassium iodide water solution (see Reagents), washing into the 
 bottle any Wijs solution on the stopper with the same. Titrate the 
 solution immediately with the 0.1 N sodium thiosulphate solution 
 (see Reagents), allowing the solution to run in slowly (about 25 to 
 80 cc) with vigorous shaking until the solution becomes a straw color. 
 
 Now add 15 cc of freshly prepared starch solution (see Reagents) 
 
 and finish titrating. The end point is sharp, as the reaction products 
 
 of shellac remain dissolved in the chloroform; any color Pete 
 
 after one-half minute or so is distegarded. 
 - A blank determination shall be run at the same time on the re- 
 agents. The blank is necessary on account of the well-known 
 effect of temperature changes on the volume and possibly loss of 
 strength of the Wijs solution. 
 From the volumes of thiosulphate solution required for the sample 
 and the blank, respectively, and the iodine value of the thiosulphate 
 solution, calculate the iodine number (centigrams of iodine per 
 gram of sample) of the shellac. 
 
 The analyst should run in parallel a sample of pure shellac of 
 
 known iodine number as a check upon the reliability of the Wijs 
 
 and thiosulphate solutions. 
 
 (6) Matter insoluble in hot 95 per cent alcohol..—Weigh accurately 
 2 g of the sample, transfer to a small beaker and heat the shellac 
 
 with 25 cc of 95 per cent alcohol (see Reagents). Prepare a Gooch 
 crucible with an asbestos pad in the customary manner and dry to 
 
 constant weight. Arrange the crucible for filtration by suction and 
 
 pour sufficient boiling alcohol oe it to eevee heat the 
 crucible. | 
 Nort.—A cold ¢rucible will congeal the wax and hinder filtration. 
 Immediately filter the boiling shellac solution, using suction, 
 transfer the insoluble matter from the beaker to the crucible, using 
 
 Se I Sd a i a 
 1 The continuous extraction method (A. 8. T. M. Standards, 1924, p, 829, Method D 29-24) may be 
 used. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 a “policeman” if necessary and a wash bottle containing hot alcohol. 
 Wash the residue in the crucible with boiling alcohol five times, 
 nearly filling the crucible each time. C Oe hi 
 Norz.—It will be necessary to shut off the suction momentarily to fill the 
 crucible. | 
 Wash off any film of shellac on the sides or bottom of the crucible 
 with hot alcohol and dry to constant weight in an oven at 105 to 
 110° C. The weight of the residue in the crucible, multiplied by 
 100 and divided by the weight of the sample, is the percentage of 
 material insoluble in hot alcohol. acorns Hed 
 (c) Moisture and volatile matter—Weigh accurately approximately 
 5 g of the sample and heat in a flat-bottomed dish about 4 inches in 
 diameter in a well ventilated air bath for three to six hours at 38 to 
 43°C. Do not allow the temperature to rise above 43° C.. 
 Nore.—With poorly ventilated ovens the drying may take much longer. 
 Completeness of drying should be ascertained by continuing the treatment to 
 constant weight. Calculate the percentage loss in weight. Ores ae | 
 (d) Matter soluble in water—Weigh 10 to 25 g of sample accurately 
 and stir thoroughly with 100 ce of distilled water in a suitable sized 
 flask or beaker. Cover with a watch glass and allow to stand at room 
 temperature (approximately 21° C.) for four hours, stirring occasion- 
 ally. Decant the water through a 12.5 cm filter paper into a weighed 
 evaporating dish, washing the shellac and paper with at least 50 cc 
 more of water. Evaporate the water and dry the extract at 105 to 
 110° C. for one hour or more to constant weight. Cool, weigh, and 
 calculate the percentage of matter soluble in water. etiette 
 (e) Waz.—Dissolve 10 g of the sample in 200 ce of 95 per cent 
 alcohol (see Reagents) with agitation at a temperature of 24° C.+ 
 3° C. Allow the solution to stand for several hours, preferably 
 overnight, in a tall cylindrical vessel maintained at a temperature of 
 24° C.+3° C. until the wax has settled to a small layer a tthe bottom 
 of the container. Decant the clear solution through a 12.5 em folded 
 filter paper, taking care not to disturb the wax layer. Finally, 
 transfer the wax to the filter, using 25 cc of alcohol at the prescribed 
 temperature. Wash the container and the wax with four 15 cc 
 portions of alcohol. The final washings should be colorless. Allow 
 most of the alcohol to evaporate from the filter paper and dissolve the 
 wax by pouring successive small portions of boiling chloroform. (see 
 Reagents) through the paper. Also wash the container with boiling 
 chloroform and pour on the filter. _ Collect the filtrate, which should 
 contain all the wax, in a tared dish, evaporate the chloroform and dry 
 to constant weight at 105 to 110° C. Weigh the wax residue and 
 calculate the percentage of wax. Tt: ae ka ‘ais , 
 The removal of the wax from the filter paper may also be accom- 
 plished in any suitable continuous ‘extraction apparatus. © © 9" 
 
SPECIFICATION FOR FLAKE ORANGE SHELLAC 5 
 
 _ (f), Ash.—Transfer an accurately weighed portion of from 2 to 3 
 g of the sample to a weighed porcelain crucible and ignite at as low 
 a temperature as possible until all organic matter has been destroyed. 
 Cool, weigh, and calculate the percentage of ash. 
 
 (g) Color—Digest a weighed portion of the sample in a closed 
 container with twice its weight of cold 95 per cent alcohol (see Re- 
 agents), shaking at intervals until the shellac is entirely “cut.” 
 Prepare in the same manner a shellac varnish with exactly the same 
 proportion of resin and alcohol, using the sample of shellac mutually 
 agreed upon for color by the buyer and seller. Compare the color 
 of these two varnishes in clear glass test, tubes of the same diameter. 
 The color of the sample under examination shall not be darker than 
 that of the sample mutually agreed upon for color by the buyer and 
 seller. 
 
 (h) Appearance-—Examine the shellac as received in the labora- 
 tory and note whether the material is ‘‘free” or not. If flakes are 
 stuck together, ascertain whether hand pressure will separate them 
 or not. | | 
 
 3. Reagents.—(a) Acetic acid.—99 per cent acetic acid having a 
 melting point of 14.8° C. free from reducing impurities, as shown by 
 its action on bichromate-sulphuric acid mixture. 
 
 (b) Wijs solution —Dissolve 13 g of pure iodine (resublimed 
 grade) in a liter of acetic acid (see (a) above) using gentle heat if 
 necessary. Cool and determine the strength by titration with 
 thiosulphate solution (see (d) below). Set aside 50 to 100 cc of the 
 solution and introduce dry chlorine gas into the remainder until a 
 characteristic color change occurs and the halogen content has 
 been doubled. By titration ascertain if the halogen content has 
 been more than doubled, and, if so, reduce it by adding a requisite 
 quantity of the iodine-acetic acid solution. The final product 
 should contain an amount of iodine and chlorine corresponding to 
 jodine-monochloride; a slight excess of iodine does no harm, but any 
 excess of chlorine over the theory for ICl must be avoided. 
 
 (©) Ohloroform.—U. S. P. chloroform should be used. | 
 --(d) Sodium thiosulphate solution.—Dissolve pure sodium thio- 
 sulphate in distilled water that has been well boiled to free it from 
 carbon dioxide in the proportion so that 24.83 g crystallized sodium 
 thiosulphate will be present in 1,000 cc of the solution. It is best 
 to let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Analytical Chemistry, 
 Treadwell-Hall, vol. II, 3d ed., p. 646.) This solution will be 
 approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust 
 it to exactly decinormal strength. Preserve in a stock bottle pro- 
 vided with a guard tube filled with soda lime. 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (e) Starch solution.—Dissolve 0.2 g of starch per 100° ce of aie 
 tilled water and boil. 
 
 (f) Potassium iodide solution.—Dissolve potassium iodide free torn 
 iodate in distilled water in the proportion of 1 part salt to 10 parts 
 of solution. 
 
 (g) Ninety-five per cent alcohol.—Hither 95 per cent ethyl alcohol 
 or 95 per cent specially denatured alcohol, U. S. Internal Revenue 
 Bureau Formula No. 1 or No. 30. (Formula No. 1 calls for the 
 addition to 100 gallons ethyl alcohol (190 proof) of 5 gallons of 
 approved wood alcohol, the wood alcohol to be subject to the same 
 specifications as are imposed upon wood alcohol used in completely 
 denatured alcohol.) (Formula No. 30 calls for the addition to 100 
 gallons of pure ethyl alcohol of 190 proof of 10 gallons of pure methyl 
 alcohol, which methyl] alcohol is to have a fi gravity of not 
 more than 0.810 at 60° F.) 
 
 VII. PACKING AND MARKING 4 
 
 There are no packing and marking requirements Sppene ura to 0 thi 
 
 specification. 
 VIII. NOTES 
 
 This specification covers the requirements for orange flake shellac 
 for use in ship bottom paints and in the preparation of orange shellac 
 varnish. In general, type A will include the grades of shellac known 
 in the trade as ‘Double triangle G,” “Diamond I,” SR RORL ! 
 and the highest grades ‘‘D. C.’”’ and ey, S..0.” 
 
 In general, type B will include the grades considered in the ae 
 as lower than ‘‘superfine,”’ but beer than ‘‘pure T. N.,” such as 
 “fine,” ‘good,’’ and “heart.” , 
 
 Bene C represents the grade aawail in the pay as pate T.. N? ” 
 This material is rosin free, but is darker and contains more insoluble 
 material than types A or B. | 
 
 Type D represents the grade known in the as “U. Ss. Ss. “ 
 T. N.” It usually contains rosin up to a maximum of 3 per cent, 
 and, in addition, it is generally darker and contains more insoluble 
 material than types A or B, but is usually a little idle in. color 
 than type C. tudiaints 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM rN 
 THE SUPERINTENDENT OF DOCUMENTS JM POA DRS 
 GOVERNMENT PRINTING OFFICE 
 beret rab D. C. 
 
 5 CENTS PRE COPY ook Bi Stee 
 Vv ry er : ™ os 
 
—_. aa: | eh es ee 
 
 U. S. Gov’t 
 Master 
 Specification 
 No. 376 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 303 
 
 [Issued February 9, 1926] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 VARNISH, SHELLAC 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 376 
 
 This specification was afiicially promulgated by the Federal Specifications 
 Board on January 25, 1926, for the use of the departments and independent 
 establishments of the Government in the purchase of varnish, shellac. 
 
 - [The latest date on which the technical requirements of this specification shall become mandatory for all 
 
 departments and independent establishments of the Government is April 26, 1926. They may be put 
 into effect, however, at any earlier date, after promulgation.] 
 
 CONTENTS 
 
 VI. Methods of sampling and testing__.--___-2__=- apn Pepe psp apes yep: TONS 
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 3 I, GENERAL, SPECIFICATIONS 
 ' There are no general specifications applicable to this specification. 
 : | I. TYPES 
 
 ‘ Shellac varnish shall be furnished as “Orange,” type 1 or 2, and 
 as “Bleached,” type 1 or 2. Each type shall be furnished as Tere 
 medium, or heavy body, as specified in the contract. 
 
 Ill. MATERIAL 
 
 Shellac varnish shall be made by “cutting” the specified type of 
 shellac, the manufactured product of stick lac (the secretion of the 
 Tacchardia Lacca) in 95 per cent specially denatured alcohol, formula 
 No. 1 of the United States Internal Revenue Bureau. 
 
 : 79614°—26t | 1 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 IV. GENERAL REQUIREMENTS 
 Therevare no general requirements applicable to this specification. 
 
 V., DETAIL REQUIREMENTS «5 4 
 
 The nonvolatile matter in ‘shellac varnish shall conform to the 
 requirements as given below for the respective types: 
 
 Iodine number (maximum) - ........-----7----2-------------<-- 
 
 Matter insoluble in hot 95 per cent alcohol (maximum) per cent. 
 
 — (martini) 2205 os Ss eee eer ae emma G0. s0= 
 Aah (maxtmuin) us ops s ose use ac sean Span be ceeeeened Gos. 
 
 Color, when erection shall be no jae than a sample of shellac 
 varnish mutually agreed upon by the buyer and seller. 
 
 The body of the respective types of varnish shall be based, es 
 the percentage of nonvolatile matter determined as in Aeghion, Mie 
 2—(a): bite Bheamehukgp 
 
 Minimum allowable percentage of nonvolatile matter: ia 
 Light body varnish. o>. .0s..0 2.222 s2eie a oo nee cnesbe se een nena an ee 
 Medium-body ‘varnish. 2 ~ 22.2 2220 22 ee ec annus ethene 
 Heavy body varnish... 5.3 oo 5<ssa<sarcancscuann anesee see wr eens nee 
 
 VI. METHODS OF SAMPLING AND TESTING 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 information to ascertain whether the materval meets the specification. 
 
 1. Samprine.—It is mutually agreed by, buyer and _seller,that a 
 single package out of each lot of not more than 1,000 packages be 
 taken as representative of the whole. ..Whenever possible an original 
 unopened container shall be sent to the laboratory, and when for any 
 reason this is not done the inspector shall thoroughly mix the contents 
 of the container sampled, transfer not less than. 1 quart to a clean dry, 
 glass bottle, which must be nearly filled with the sample, securely 
 stoppered with a new clean cork or well-fitting cover or cap, sealed 
 and distinctly labeled by the inspector. The inspector should take 
 a duplicate from the container sampled, to be held for check in case 
 of dispute, and when requested should take a sample for the seller. _ 
 
 2. LABORATORY EXAMINATION.— (a) Nonvolatile matter. Place’ a 
 portion of the thoroughly mixed ee, in a stoppered bottle or A 
 
“SPECIFICATION FOR SHELLAC VARNISH 3 
 
 ing pipette... Weigh the container and sample. - Transfer 1.25 g (40.25 
 g) of the sample to a weighed flat-bottomed metal dish about 8 cm-in 
 diameter (a friction-top can plug). Weigh the container again and 
 by difference calculate the exact weight of the portion transferred to 
 the weighed dish. Heat the dish and its contents in an oven main- 
 tained at 105 to 110° C. for three hours, cool, and weigh. From the 
 weight of the residue left in the dish and the weight of the sample 
 taken calculate the percentage of nonvolatile residues 
 
 (b) Iodine number of the nonvolatile residue.—Transfer 1.5 cc of the 
 shellac varnish by means of a pipette to a flat-bottomed glass or por- 
 celain dish at least 8 cm in diameter. Add 1 to 2 cc of 95 per cent 
 alcohol. to spread the varnish evenly over the bottom of the dish. 
 Heat the dish and contents at 85 to 90° C. for one-half hour. Scrape 
 the residue from the dish and place 0.2 g in a 250 ce dry bottle of 
 clear glass with a ground-glass stopper, add 20 cc of glacial acetic 
 acid (see Reagents), and warm the mixture gently on top of a hot- 
 water bath until solution is complete (except for the wax). A pure 
 
 ‘shellac is rather difficultly soluble; solution is quicker according to 
 ‘the proportion of rosin present. Add 10 cc of chloroform (see Re- 
 
 agents), and cool the solution to 21.5 to 22.5° C. The bottles should 
 be allowed to stand half immersed in a shallow pan of water, well 
 
 ’ insulated or equipped with a suitable thermostat, at least 30 min- 
 
 utes at 21.5 to 22.5° C. before the Wijs solution (see Reagents) is 
 added. Add 20 cc of Wijs solution, (which shall be at a temperature 
 of 21.5 to 22.5° C.) from a pipette, having a rather small delivery 
 aperture (about 30 seconds). Close the bottle, place it back into the 
 pan of water, and note the time. The bottles must be kept half im- 
 mersed in water at 21.5 to 22.5° C. during the one hour that the shellac 
 is exposed to the Wijs solution. Agitate the bottles ancasiopally 
 during that hour. 
 
 _Nors.—If a number of samples are being run, at least five minutes should 
 be allowed between the additions of the Wijs solution. 
 
 After exactly one hour add 10 cc of freshly prepared 10 per cent 
 
 potassium iodide water solution (see Reagents), washing into the 
 
 bottle any Wijs solution on the stopper with the same. Titrate the 
 solution immediately with the 0.1 N sodium thiosulphate solution 
 (see Reagents), allowing the solution to run in slowly (about 25 to 
 30 cc), with vigorous shaking until the solution becomes a straw 
 color. Now-add 15 cc of freshly prepared starch solution (see Re- 
 agents) and finish titrating. The end point is sharp, as the reaction 
 products of shellac remain dissolved in the chloroform; any color re- 
 turning after one-half minute or so is disregarded. 
 
 1 The method described in Tentative Methods of Testing Shellac Varnish, published by the A. S. T. M. 
 in 1925 may be followed, but the calculation shall be based on solids determined without any allowance for 
 an assumed moisture content in the shellac, since this has been allowed for in the specification. 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 A blank determination shall be run at the same time on the re- 
 agents. The blank is necessary on account of the well-known effect 
 of temperature changes on the volume and possibly loss of fret 
 of the Wijs solution. 
 
 From the volumes of thiosulphate solution required for the 
 sample and the blank, respectively, and the iodine value of the 
 thiosulphate solution, Galoalatd the iodine number PCR of 
 iodine per gram of sample) of the shellac. 
 
 The analyst should run in parallel a sample of cis shellac of 
 known iodine number as a check upon the reliability of the Wijs and 
 thiosulphate solutions. 
 
 (c) Material insoluble in hot 95 per cent aleohols 2.::/Rhiofodghly 
 shake the sample and at once place a portion of the well-mixed sam- 
 ple in a stoppered bottle or weighing pipette. Weigh the contaier 
 and sample, thoroughly mix by shaking, and transfer approximately 
 5 cc of the sample to a small beaker. Weigh the container again and 
 by difference calculate the exact weight of the portion transferred 
 to the beaker. Heat the shellac varnish in the beaker with 25 ec 
 of 95 per cent alcohol (see Reagents). Prepare a Gooch crucible 
 with an asbestos pad in the customary manner and dry to constant 
 weight. Arrange the crucible for filtration by suction and pour 
 sufficient boiling alcohol through it to heat thoroughly the crucible. ° 
 
 Nors.—A cold crucible will congeal the wax and hinder filtration. 
 
 Immediately filter the boiling shellac solution, using suction, 
 transfer the insoluble matter from the beaker to the crucible, using 
 a “policeman” if necessary and a wash bottle containing hot alcohol. 
 Wash the residue in the crucible with boiling alcohol: are — 
 nearly filling the crucible each time. | 
 
 Nore.—It will be necessary to shut off the suction Gre ag eign 2 to me the 
 crucible. 
 
 Wash off any film of shellac on the sides or bottom ss the tae 
 with hot alcohol and ‘dry to constant weight in an oven at 105 to 
 110° C. The weight of the residue in the crucible multiplied | by 
 100 and divided by “the weight of the nonvolatile matter in the sample 
 taken is the percentage of Tatetial insoluble in hot alcohol. 
 
 (d) Waxz.—Thoroughly mix the sample and at once transfer a 
 weighed portion of approximately 30 g to a tall cylindrical vessel. 
 Dilute the varnish with 180 ec of 95 per cent alcohol (see Reagents) at 
 a temperature of 24° 0.+3° ©. and thoroughly mix. Allow the 
 solution to stand for several hours, preferably overnight in a tall cylin- 
 drical vessel maintained at a temperature of 24° C.+3° C. until the 
 a a 
 
 2“'The continuous extraction method” (A. 8. T. M, Standards, 1924, p. mass Method Assisi may also 
 be used, . 
 
SPECIFICATION FOR SHELLAC, VARNISH 5 
 
 wax has settled to a small layer at the bottom of the container. 
 Decant the clear solution through a 12.5 cm folded filter paper, taking 
 care not to disturb the wax layer. Finally, transfer the wax to the 
 filter, using 25 cc of alcohol at the prescribed temperature. Wash 
 the container and the wax with rour 15 cc portions of alcohol. The 
 final washings should be colorless. Allow most of the alcohol to 
 evaporate from the filter paper and dissolve the wax by pouring suc- 
 cessive small portions of boiling chloroform (see Reagents) through 
 the paper. Also wash the container with boiling chloroform and 
 pour on the filter. Collect the filtrate, which should contain all 
 the wax, in a tared dish, evaporate the chloroform and dry to con- 
 stant weight at 105 to i10° C. Weigh the wax residue and calculate 
 the percentage of wax based on the weight of nonvolatile residue in the 
 sample of shellac varnish taken. 
 
 The removal of the wax.from the filter paper may also be accom- 
 plished in any suitable continuous extraction apparatus. 
 
 (e) Ash.—Transfer an accurately weighed portion of 5 to 6 g of 
 the sample to a weighed porcelain crucible and evaporate most of 
 the alcohol on the steam bath. Ignite at as low a temperature as 
 possible until all organic matter has been destroyed. Cool, weigh, 
 and calculate the percentage of ash based upon the weight of non- 
 volatile material in the sample of varnish taken. 
 
 (f) Color.—Compare the color of the sample under examination 
 
 with the color of the sample mutually agreed upon for color by the 
 buyer and seller in clear glass test tubes of the same diameter. 
 
 _ The color of the sample under examination shall not be darker 
 than the color of the sample mutually agreed upon for color by the 
 buyer and seller. 
 
 Notse.—The sample used for color comparison should be kept in a glass con- 
 tainer in a dark place. 
 
 3. Reacents.—(a) Acetic acid.—Ninety-nine per cent acetic acid 
 having a melting point of 14.8° C., free from reducing impurities as 
 shown by its action on bichromate-sulphuric acid mixture. 
 
 (b) Wajs solution.—Dissolve 13 g of pure iodine (resublimed grade) 
 _in a liter of acetic acid (see (a) above), using gentle heat if necessary. 
 Cool and determine the strength by titration with thiosulphate solu- 
 tion (see (d) below). Set aside 50 to 100 ce of the solution and intro- 
 duce dry chlorine gas into the remainder until a characteristic color 
 change occurs and the halogen content has been doubled. By titra- 
 tion ascertain if the halogen content has been more than doubled, 
 ‘and, if soy reduce it by adding a requisite quantity of the iodine- 
 acetic atid solution. The final product should contain an amount of 
 iodine and chlorine corresponding to iodine-monochloride; a slight 
 excess of iodine does no harm, but any excess of chlorine over the 
 theory for ICl must be avoided. 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (c) Chloroform.—U. Sv P. chloroform should be used.” bore 
 meee: “thiowl 
 phate in distilled ae that has ween well boiled to free it from 
 carbon dioxide in the proportion so that 24.83 g crystallized sodium 
 thiosulphate will be present in 1,000 ce of the solution. “It is best to 
 let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine. (See Analytical Chemis- 
 try, Treadwell-Hall, Vol. II, 3d ed., p. 646.) This solution ‘will be 
 approximately decinormal, and it is best to leave it as it-is after deter- 
 
 mining its exact iodine value, rather than to attempt to adjust it to 
 
 exactly decinormal strength. Preserve in a stock bottle provided 
 with a guard tube filled with soda lime. 
 
 (e) Starch solution.—Dissolve 0.2 g of starch per 100 cc of distilled 
 water and boil. 
 
 (f) Potassium iodide solution.— Dissolve potassium iodide free from 
 iodate in distilled water in the proportion of 1 part salt to 10 parts 
 of solution. 
 
 (g) Ninety-five per cent alcohol.—Either 95 per cent ne Alcohol 
 or 95 per cent specially denatured alcohol, United States Internal 
 Revenue Bureau Formula No. 1 or No. 30. (Formula No. 1 calls for 
 the addition to 100 gallons ethyl alcohol (190 proof) of 5 gallons ap- 
 proved wood alcohol, the wood alcohol to be subject: to the same 
 specifications as are imposed upon wood alcohol used in ‘eompletely 
 denatured alcohol. | Formula No. 30 calls for the addition to 100 gal- 
 lons ethyl alechol of 190 proof of 10 gallons of pure methyl alcohol, 
 which methyl alcohol is to have a specific gravity of not more than 
 0.810 at 60° F.) 
 
 VIl. PACKING AND MARKING 
 
 Shellac varnish shall be shipped in containers that. will not darken 
 the product during storage. 
 
 VIIt. NOTES 
 
 This specification is intended to cover all the needs of the Govern- 
 - ment for shellac varnish, both orange and bleached. Bleached shel- 
 lac varnish is sometimes known as white shellac varnish. In‘general, 
 type 1 of orange shellac varnish will include the rosin-free material 
 and the lighter colored varnishes, while type 2 is intended for use 
 where the presence of small percentages of rosin (not over 3 per cent) 
 is not objectionable and where lightness of color is not an pega: 
 factor. 
 
 In general, type 1 of bleached shellac varnish will fulfill all the 
 needs for a white shellac varnish. Type 2 will be used only im cases 
 
SPECIFICATION FOR SHELLAC VARNISH fi 
 
 where a clear bleached varnish (practically free from wax or other 
 suspended matter) is necessary. 
 Light, medium, and heavy body varnishes correspond to 3.5, 4.0, 
 and 4.5 pound ‘“‘cuts” of shellac, respectively. The minimum 
 | allowable percentages of nonvolatile matter for each body of varnish 
 given in Section V of this specification have been corrected for maxi- 
 mum moisture and volatile matter in flake orange shellac of 2 per 
 cent and in bleached dry shellac of 5 per cent, so that varnishes 
 made by cutting 3.5, 4.0, and 4.5 pounds of either orange or bleached 
 shellac in 1 gallon of specially denatured alcohol should meet the 
 nonvolatile requirements of Section V. 
 
 ADDITIONAL COPIES 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 AT 
 
 5 CENTS PER COPY 
 4 
 
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OO 
 
 U. S. Gov’t 
 Master 
 Specification 
 
 No. 475a 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 
 George K. Burgess. Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 330 
 
 {Issued April 28, 1927] 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 OIL, LINSEED, BOILED ' 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 475a 
 [Revised March 5, 1927] 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on February 3, 1922, for the use of the departments and independent 
 establishments of the Government in the purchase of boiled linseed oil. 
 
 [The latest date on which the technical requirements of this revision of this specification shall become 
 mandatory for all departments and independent establishments of the Government, is June 6, 1927. They 
 may be put into effect, however, at any earlier date.] 
 
 CONTENTS 
 
 Be eeetrernerinl Sir Wor kitianahin.$ — ois eA ong an pene 
 LST RSS a5 a gg gm 
 S wetesanemed viromon testis be ke Ll Sotel Siled A eyo tli 
 VI. Methods of sampling, testing, and basis of purchase_____________-_ 
 ee RMN = ei ig ee. Let en Bk ee a ee 
 
 I Rg ine ce ee Rr ae de eo tT oe pe 
 ENE OES IIE Sarat alecapiaetiegs Dy. Dayne ee SNES MCE 
 
 EP PE TESCO an oe lo es ee ln 
 Une OM MNTTents. ee tee eee 
 VIII. Notes___.--_-- es PORES SiS. SPS s28 tS ee ay SOY Sass 
 
 Go 0. ~1'@ ks WR hok> Rt 
 
 1 For raw linseed oil see United States Government master specification for raw linseed oil, Federal 
 Specifications Board specification No. 4a (Bureau of Standards Circular No. 82, 3d ed.). This specifica- 
 tion (F. 8. B. specification No. 475a) supersedes that part of F. 8. B. specification No. 4, which covered 
 boiled linseed oil, 
 
 43232°—27 
 
2 CIRCULAR OF THE BUREAU OF STANDARDS 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification. 
 Il. TYPES 
 
 A. Kettle-boiled linseed oil. 
 B. Quick process boiled linseed oil. 
 
 Ill. MATERIAL AND WORKMANSHIP 
 See detail requirements. 
 IV. GENERAL REQUIREMENTS 
 See detail requirements. | 
 V. DETAIL REQUIREMENTS 
 
 Boiled linseed oil shall be pure linseed oil that has been treated 
 (preferably by heating—kettle boiled) with compounds of lead, and 
 at the option of the manufacturer with suitable compounds of other 
 drying metals, so as to produce a product that will dry rapidly. It 
 shall be clear, free from sediment, and shall meet the following 
 requirements: 
 
 Maximum | Minimum 
 
 Time of drying on glass.......-~--.--<-.~.. 5st dees Geta aee © eee Seem JU hours... 180 TN nteteenoole 
 Loss on’heating at 105 to 110°. O.. .250- 5.35 ence ancicee poneeceeuseweuse per cent.- Fe tg Baty co aussi ie 
 Specific gravity at 15.5/15.5° C_-_-.-..----------------------- eo on nnn een nennnn . 945 10, 937 
 Reid num bor: on oo needs boda dacaconnsn ce aeicassareeseeeunee yee eee e aaa 7.8 i eee 
 Saponification number-_.---.----.--------------------------4ne0- nen +e Soe ses sneer 195.0 189.0 
 Unsaponifiable matter... ...2 2. -s20<-- cence ne cen wn enenonsresacenneesas per cent_. 1500 cones cee se 
 Todine number... ockonceew wen oka oe eh ewe ich ole u~ tak a teee ewe eee sews Ws. s] weaconsee tee 168. 0 
 se ep wbucusbecbewdlwena cede adea scone ea cewae seared paten sete Marrero per cent. » DD Hedin deta 
 Thond eon wet oes ae ee ea i eae nde ee eee ee GO0icuoleedtaaesueee 05 
 
 ht quick process, not kettle boiled, oil is called for in contract, the minimum specific gravity shall 
 9300. - 
 
 VI. METHODS OF SAMPLING, TESTING, AND BASIS OF 
 PURCHASE , 
 
 Deliveries will, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to .use any additional 
 available information to ascertain whether the material meets the speci- 
 fication. ik aba 
 
 1. SAMPLING 
 
 The method of sampling given under (a), below, should be used 
 whenever it is feasible to apply it. To meet conditions when (@) is 
 not applicable, method (6), (c), or (d) is to be used, according to the 
 special conditions that obtain. | 
 
ae ee Ss ee 
 
 ai peat al 
 
 SPECIFICATION FOR BOILED LINSEED OIL 3 
 
 (a) Durine Loapine or TanK Cars or FILLING oF CONTAINERS 
 FOR SHIPMENT AT THE Factrory.—The purchaser’s inspector shall 
 draw a sample at the discharge pipe where it enters the receiving 
 vessel or vessels. The total sample shall be not less than 5 gallons 
 and shall be a composite of small samples of not more than 1 pint, 
 each taken at regular intervals during the entire period of loading or 
 filling. | 
 
 The sample thus obtained shall be thoroughly mixed, and fro 
 this composite sample three portions of not less than 1 quart each 
 shall be placed im clean, dry glass bottles or tin cans which must be 
 filled with the sample and securely stoppered with new clean corks 
 or well fitting metal covers or caps. These shall be sealed and labeled 
 distinctly by the inspector, and one delivered to the buyer, one to the 
 seller, and the third held for check in case of dispute. 
 
 (6) From Loapgep Tank Cars or OTHER LarcEe Vessets.—The 
 total sample shall be not less than 5 gallons and shall be a composite 
 of numerous small samples of not more than 1 pint each, taken from 
 the top, bottom, and intermediate points by means of a glass or metal 
 container with removable stopper or top. This device attached to a 
 suitable pole is lowered to the various desired depths when the 
 stopper or top is removed and the container allowed to fill. The 
 sample thus obtained is handled as in (@). 
 
 (c) Barrets AND Drums.—Not less than 5 per cent of the packages 
 in any shipment or delivery of barrels and drums shall be sampled. 
 The packages shall be shaken, rolled, and stirred to mix the contents 
 thoroughly. The samples from the individual containers shall be 
 taken through the bung hole or holes not less than 114 inches in 
 diameter, bored in the head or side for the purpose. The apparatus 
 for drawing the sample shall consist of a glass tube about 1 inch in 
 diameter and somewhat longer than the length or diameter of the oil 
 container, a conical stopper that will fit the glass tube and is not more 
 than one-half inch long fastened to a stiff metal rod not more than one- 
 
 fourth inch in diameter and not less than 4 inches longer than the 
 
 glass tube. The stopper is lowered by the rod until it rests on the 
 bottom of the cask, the tube slipped down slowly over the rod, and 
 finally pressed on the stopper. By holding tube and rod the column 
 of oil can then be removed. This process is repeated until the re- 
 quired amount of sample is obtained, which must not be less than 2 
 gallons This is mixed and handled as in (q). 
 
 (2) Smati Conrarners, Cans, Erc., of 10 GatLons or Less.— 
 Small containers, cans, etc., of 10 gallons or less should be sampled 
 while filling by method (a) whenever possible. When method (a) 
 is not applicable, it is mutually agreed that: In all cases the total 
 sample taken shall not be less than 3 quarts. This shall be obtained 
 by taking at least 1 package from each lot of not more than 300 
 
4. CIRCULAR OF THE BUREAU OF STANDARDS 
 
 packages. The sample thus taken shall be thoroughiy mixed and 
 subdivided as in (a). 
 2. TESTING 
 
 All tests shall be made on oil that has been thoroughly agitated 
 before removal of a portion for analysis. 
 
 (a) Time or Dryine on Guass.—Flow the oil over a perfectly 
 ‘hn glass plate. Place plate in a nearly vertical position im air 
 that is between 15 and 35° C. and of humidity between 48 and 60 
 per cent saturation. After about two hours test the film at intervals 
 with the finger at points not less than 214% cm from the edges. The 
 film will be considered dry when it no longer adheres to the finger 
 and does not rub up appreciably when the finger is lightly rubbed 
 across the surface. 
 
 (6) Sprciric Graviry.—Determine at 15.5/15.5° C. by any con- 
 venient method that is accurate within two points in the fourth 
 decimal place. 
 
 (c) Acrpy Numper.—Weigh from 5 to 10 g of the oil. Transfer 
 to a 300 cc Erlenmeyer fiask. Add 50 cc of a mixture of equal parts 
 by volume of 95 per cent ethyl alcohol and c. p. reagent benzol. 
 (This mixture should previously be titrated to a very faint pink 
 with dilute alkali solution, using phenolphthalein as an indicator.) 
 Add phenolphthalein indicator and titrate at once to a faint perma- 
 nent pink color with standard sodium or potassium hydroxide solu- 
 tion. Calculate the acid number (milligrams KOH) per gram of oil. 
 
 (d) SAPONIFICATION NumBER.—Weigh about 2 ¢ of the oil and 
 transfer to a 300 cc Erlenmeyer flask. Add 25 ce of alcoholic sodium 
 hydroxide or potassium hydroxide solution. Put a condenser loop 
 inside the neck of flask and heat on the steam bath for one hour. 
 Cool, add phenolphthalein as indicator, and titrate with 0.5 N 
 H.SO,. Run two blanks with the alcoholic alkali solution. ‘These 
 should check within 0.1 cc of 0.5 N H,SO,. From the difference 
 between the number of cubic centimeters of 0.5 N H,SO, required 
 for the blank and for the determination, calculate the sapere 
 number (milligrams KOH required for 1 g of the oil). 
 
 (ec) UNSAPONIFIABLE Matrer.—Weight 8 to 10 g of the oil and 
 transfer to a 250 cc long neck flask. Add 5 ce of a concentrated | 
 solution of sodium hydroxide (equal weights of NaOH and H;O) and 
 50 ce of 95 per cent ethyl alcohol. Put a condenser loop inside 
 the neck of the flask and boil for two hours. Occasionally agitate 
 the flask to break up the liquid, but do not project the liquid onto 
 the sides of the flask. At the end of two hours, remove the con- 
 denser and allow the liquid to boil down to about 25 cc. 
 
 Transfer to a 500 cc glass-stoppered separatory funnel, rinsing 
 with water. Dilute with water to 250 cc, add 100 ce of redistilled 
 ether. Stopper and shake for one minute. Let stand until the 
 
SPECIFICATION FOR BOILED LINSEED OIL 5 
 
 two layers separate sharp and clear. Draw all but one or two 
 drops of the aqueous layer into a second 500 cc separatory funnel 
 and repeat the process using 60 cc of ether. After thorough sepa- 
 ration, draw off the aqueous solution into a 400 cc beaker, then the 
 ether solution into the first separatory funnel, rinsing down with 
 a little water. Return the aqueous solution to the second separa- 
 tory funnel and shake out again with 60 cc of ether in a similar 
 manner, finally drawing the aqueous solution into the beaker and 
 rinsing the ether into the first separatory funnel. 
 
 Shake the combined ether solution with the combined water 
 rinsings and let the layers separate sharp and clear. Draw off the 
 water and add it to the main aqueous solution. Shake the ether 
 solution with two portions of water (about 25 cc each). Add these 
 to the main water solution. 
 
 Swirl the separatory funnel so as to bring the last drops of water 
 down to the stopcock and draw off until the ether solution just fills 
 the bore of the stopcock. Wipe out the stem of the separatory 
 funnel with a bit of cotton on a wire. Draw the ether solution 
 (portion wise if necessary) into a 250 cc flask and distill off. While 
 still hot, drain the flask into a small weighed beaker, rinsing with a 
 little ether. Evaporate this ether, cool the beaker, and weigh. 
 (The unsaponifiable oil from adulterated drying oils may be volatile 
 and as a consequence may evaporate on long heating. Therefore, 
 heat the beaker on a warm plate, occasionally blowing out with a 
 current of dry air. Discontinue heating as soon as the odor of ether 
 is gone.) 
 
 (f) loptns Numsper.—Place a small quantity of the sample in a 
 small weighing burette or beaker. Weigh accurately. Transfer by 
 dropping from 0.09 to 0.15 g of oi to a 500 cc bottle, having a 
 well-ground glass stopper, or an Erlenmeyer flask, having a specially 
 flanged neck for the iodine tests. Reweigh the burette or beaker 
 and determine the amount of sample used. Add 10 cc of chloro- 
 form. Whirl the bottle to dissolve the sample. Add 10 cc of 
 chloroform to each of two empty bottles or flasks like that used for 
 the sample. Add to each bottle 25 cc of the Wijs solution and let 
 ‘stand with occasional shaking for one hour in a dark place at a tem- 
 perature of from 21 to 23°C. Add 10 cc of the 15 per cent potassium 
 iodide solution and 100 cc of water. Titrate with 0.1 N sodium 
 thiosulphate, using starch as an indicator. The titrations on the 
 two blank tests should agree within 0.1 cc. From the difference 
 between the average of the blank titrations and the titration on the 
 samples and the iodine value of the thiosulphate solution calculate 
 the iodine number of the samples tested. (lodine number is given in 
 centigrams of iodine to 1 g of sample.) 
 
6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 (g) Loss on Heatine at 105 to 110° C.—Place 10 g of the oil in 
 an accurately weighed 50-cc Erlenmeyer flask and weigh. Heat in 
 an oven at a temperature between 105 and 110° C. for 30 minutes, 
 then cool and weigh. Calculate the percentage loss. This deter- 
 mination shall be made in a current of carbon dioxide. 
 
 (hk) Asu.—Tare a porcelain crucible or dish. Add 10 to 25 ce of 
 oil, carefully weighing the amount added. Place on a stone slab on 
 the floor of a hood. Ignite by playing the flame of a burner on the 
 surface of the oil and allow to burn quietly until most of the oil is 
 burned off; then transfer to a muffle or over a flame and continue 
 heating at a low temperature (not over a dull red) until all carbona- 
 ceous matter is consumed. Cool, weigh, and compute the percentage 
 of ash. 
 
 (1) Leap.—Dissolve the ash (h) in dilute nitric acid to which 
 a little hydrogen peroxide has been added and determine lead by the 
 sulphate or any other equally accurate method. 
 
 (7) ApPEARANCE.—Transfer a portion of the sample to a clear glass 
 tube and note appearance. 
 
 3. REAGENTS 
 
 (2) SraNDARD Sopium HyproxipE SoLuTION. —Prepare a stock 
 concentrated solution of sodium hydroxide by dissolving sodium 
 hydroxide in water in the proportion of 200 g NaOH to 200 cc water. 
 Allow this solution to cool and settle in a stoppered bottle for several 
 days. Decant the clear liquid from the precipitate of sodium car- 
 bonate into another clean bottle. Add clear barium hydroxide 
 solution until no further precipitate forms. Again allow to settle 
 until clear. Draw off about 175 cc and dilute to 10 liters with freshly 
 boiled distilled water. Preserve in a stock bottle provided with 
 a large guard tube filled with sodalime. Determine the exact strength 
 by titrating against pure benzoic acid (CsH;COOH), using phenol- 
 phthalein as indicator. (See Bureau of Standards Scientific Paper No. 
 183.) This solution will be approximately one-fourth normal, but 
 do not attempt to adjust it to any exact value. Determine its exact 
 strength and make proper corrections in using it. 
 
 (6) Auconotic Soprum Hyproxipr Soiution.—Dissolve pure 
 sodium hydroxide in pure 95 per cent ethyl alcohol im the propor- 
 tion of about 22 g per 1,000 cc. Let stand in a stoppered bottle, 
 decant the clear liquid mis another bottle, and keep well stoppered. 
 This solution should be colorless or only slightly yellow when used. — 
 
 (c) Stanparp Sopium TxHtosuLtpHaTe SoLtution.—Dissolve pure 
 sodium thiosulphate in distilled water that has been well boiled to 
 free it from carbon dioxide in the proportion so that 24.83 ¢ crystal- 
 lized sodium thiosulphate will be present in 1,000 ec of the solution. 
 It is best to let this solution stand for about two weeks before stand- 
 
 ~ 
 
SPECIFICATION FOR BOILED LINSEED OIL "4 
 
 ardizing. Standardize with pure resublimed iodine. (See Analyti- 
 cal Chemistry, Treadwell-Hall, vol. 2, 6th ed., p. 551.) This solu- 
 tion will be approximately decinormal, and it is best to leave it as 
 it is after determining its exact iodine value, rather than to attempt 
 to adjust it to exactly decinormal strength. Preserve in a stock 
 bottle provided with a guard tube filled with soda lime. 
 
 (dq) Srarcu SoLuTion.—Stir up 2 or 3 g of potato starch or 5 g 
 soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
 300 to 400 cc boiling water, and boil the mixture until the starch 
 appears to be dissolved. Dilute to 1 liter. 
 
 (e) Porasstum lopipr Sontution.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 cc. 
 
 (f) Wiss Sotution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine or more particularly 
 of chlorine over that required to form the monochloride. This con- 
 dition is most satisfactorily attained by dissolving in the whole of the 
 acetic acid to be used the requisite quantity of iodine, using a gentle 
 heat to assist the solution, if it is found necessary. Dissolve iodine 
 in glacial acetic acid that has a melting point of 14.7 to 15° C. and is 
 free from reducing impurities, in the proportion so that 13 g of iodine 
 will be present in 1,000 cc of solution. Set aside a small portion of 
 this solution while pure, and pass. dry chlorine into the remainder 
 until the halogen content of the solution is doubled. Ordinarily it 
 will be found that by passing the chlorine into the main part of the 
 solution until the characteristic color of free iodine has just been dis- 
 charged, there will be a slight excess of chlorine, which is corrected 
 by the addition of the requisite amount of the unchlorinated portion, 
 until all free chlorine has been destroyed. A slight excess of iodine 
 does little or no harm, but excess of chlorine must be avoided. 
 
 (g) Hatr Norma Sutpnuric Acip Sotution.—Add about 15 cc 
 sulphuric acid (1.84 specific gravity) to distilled water, cool and 
 dilute to 1,000 cc. Determine the exact strength by titrating against 
 freshly Pe idatdized sodium hydroxide or by any other accurate 
 method. Either adjust to exactly half normal strength or leave as 
 originally made, applying appropriate correction. 
 
 4. BASIS OF PURCHASE 
 
 Material is to be purchased by weight or volume, as specified in 
 the contract. When purchased by volume, 1 gallon of oil shall mean 
 231 cubic inches at 15.5° C. 
 
8 CIRCULAR OF THE BUREAU OF STANDARDS 
 VII. PACKING OF SHIPMENTS 
 
 Packing shall be in accordance with commercial practice unless 
 otherwise specified. | 
 VIII. NOTES 
 
 This specification supersedes that part of Federal Specifications 
 Board specification No. 4 (Bureau of Standards Circular No. 82, 2d 
 ed.), which covered boiled linseed oil. For specification for raw lin- 
 seed oil-see Federal Specifications Board specification No. 4a (Bureau 
 of Standards Circular No. 82, 3d ed.). The specification for refined 
 linseed oil contained in F erarnt Specifications Board specification 
 No. 4 (Bureau of Standards Circular No. 82, 2d ed.) is revoked. 
 
 For formulas and methods of using this A Ir Hs and information 
 regarding the use of other specification paint materials see Bureau 
 of Standards Technologic Paper No. 274, entitled “Use of United 
 States Government Specification Paints a Paint Materials.” 
 
 ADDITIONAL COPIES 
 
 OF THIS PUBLICATION MAY BE PROCURED FROM 
 THE SUPERINTENDENT OF DOCUMENTS 
 GOVERNMENT PRINTING OFFICE 
 WASHINGTON, D. C. 
 
 AT 
 
 6 CENTS PER COPY © 
 Vv Vitruyitys 
 
U. S. Gov’t 
 Master 
 Specification 
 No. 476 
 
 DEPARTMENT OF COMMERCE 
 BUREAU OF STANDARDS 
 
 George K. Burgess, Director 
 
 CIRCULAR OF THE BUREAU OF STANDARDS, No. 331 
 
 [Issued April 29, 1927] 
 
 e 
 
 UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
 CHROME YELLOW (LEMON, MEDIUM, AND ORANGE; DRY, 
 PASTE IN OIL, AND PASTE IN JAPAN) 
 
 FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 476 
 
 This specification was officially promulgated by the Federal Specifications 
 Board on March 5, 1927, for the use of the departments and independent 
 establishments of the Government in the purchase of chrome yellow (lemon, 
 medium and orange; dry, paste in oil, and paste in japan). 
 
 [The latest date on which the technical requirements of this specification shall become mandatory for all 
 departments and independent establishments of the Government is June 6, 1927. They may be put into 
 effect, however, at any earlier date after promulgation.] 
 
 CONTENTS 
 
 * Page 
 
 I EATER UT i ee cede tm ee eee cds 2 
 NEMS Ferre Je re ro fo oe oe eo ee Mee ee 2 
 Mii iMasetialand workmanship 5... 4.ice0s_ lewis Jiu ul ue ate cul Z 
 Dee seeere remiromente 6406. 284s die eis 56 es hele cn we 2 
 lee ere POMOC OTS sn ee a ho io Se oe ir se ek a gen ots 2 
 oI te aie dake, cath phates J pally Satis TS kai MRE a Mi eget 2 
 
 ci ge ge SE IE RL RS lg « Slat sgety ofp tenia te Opie inert 2 
 
 SEU GES 21 FREI ade emcarrictin nip ate is NSA SEES ae 3 
 
 VI. -Metheds of sampling and testing-.---.--2222-222 ls scr c2 lee 3 
 MIAO er sur Pee et i See eo Fee oF oes 3 
 
 2. Laboratory examination, dry pigment__-_.._--2 _-_2-- 2. 4 
 
 3. Laboratory examination, paste in oil_..._.......--------.. 5 
 
 4. Laboratory examination, paste in japan__.______---___-_.- 8 
 EEE gia 14. Seep apoeeyo-ae Ws (REY Raa BOO EL NAY 7 SO RPC UN ATA seep NE 9 
 
 ae EMEC 8 SATIS NST Gerla ry rae nr era 10 
 ERs SNe dos hte aided pelo ahce Ros 2 by eede bs Set d-SHteu eek 10 
 
 43233°—27 
 
yi) CIRCULAR OF THE BUREAU OF STANDARDS 
 
 I. GENERAL SPECIFICATIONS 
 There are no general specifications applicable to this specification. 
 II. GRADES 
 
 This specification covers the grade of chrome yellow commonly 
 known in the trade as “‘C. P.”” It covers a wide variety of lemon, 
 medium, and orange yellows, both as dry pigments, as pastes in oil, 
 and as pastes in japan. 
 
 III. MATERIAL AND. WORKMANSHIP 
 See detail requirements. 
 IV. GENERAL ee 
 See detail requirements. 
 V. DETAIL REQUIREMENTS 
 
 1. DRY PIGMENTS 
 
 The dry pigments shall be chemical precipitates consisting of 
 normal or basic lead chromates or mixtures of these with or without 
 admixtures of other insoluble compounds of lead, but without any 
 other admixtures, and shall conform to the following requirements: 
 
 Maximum 
 
 per cent 
 Coarse particles (residue retained on No. 325 sieve).--.--------+----2--5 (10) 
 ‘Total matter soluble in water... ......2=.-.-2-46.+.++- osu ee eee oe: 
 Total of all substances other than compounds of lead___.-.------------ 3. 0 
 Organic colors or lakes__._.-_...-~-----enen-e2-~=nde eer anees See None. . 
 
 The mass color and character of the tint shall be the same as and 
 the tinting strength shall not be less than those of a sample mutually 
 agreed upon by buyer and seller. 
 
 2. PASTE IN OIL 
 
 The paste color in oil shall consist of the pigment described kbitle 
 ground to a paste in linseed oil. The paste as received shall not be 
 caked in the container and shall break up readily in linseed oil to 
 form a smooth paint of brushing consistency and shall conform to the 
 following requirements: 
 
 — 
 
 3 
 
 Maximum | Minimum 
 
 Per cent Per cent 
 Pinment . 02. ono calenccnaatacrehungs dapeineseuseecbineseneendesuh sane line 75 
 
  DiSrrssed OF enone nie occ nw iomeremnconnbdibee. Abt See ek ole Aen ee oe ES RY Rapes est 
 Water and other volatile matter... 550... i. sd caus eta es aenee ee nenee eee 1 ER REN Lie 
 Coarse particles and skins-(total residue retained on No. 325 sieve) ...----------- ok! Px « fp nets a 
 
 The mass color and character of the tint shall be the same as and 
 the tinting strength shall be not less than those of a sample mutually 
 agreed upon by the buyer and seller. 
 
SPECIFICATION FOR CHROME YELLOW 3 
 
 3. PASTE IN JAPAN 
 
 The paste color in japan shall consist of the pigment described above 
 thoroughly ground to a paste in high-grade grinding japan. The 
 paste as received shall not be caked in the container and shall break 
 up readily in turpentine to form a smooth paint of brushing con- 
 sistency that will dry within’one hour to a hard, flat coat that can 
 be varnished within five hours of time of application without streaking 
 or bleeding. It shall also conform to the following requirements: 
 
 Maximum | Minimum 
 
 Percent Per cent 
 70 
 
 BoM we eee ae ek ed) sa I a os Bee GH D4 
 Vehicle {containing not less than 40 per cent of nonvolatile matter)___......._.-_ 7 SR satan ES 
 
 The mass color and character of the tint shall be the same as and 
 the tinting strength shall be not less than those of a sample mutually 
 agreed upon by the buyer and seller. 
 
 VI. METHODS OF SAMPLING AND TESTING 
 
 Deliveries wil, in general, be sampled and tested by the following 
 methods, but the purchaser reserves the right to use any additional 
 information to ascertain whether the material meets the specification. — 
 
 1. SAMPLING 
 
 It is mutually agreed by buyer and seller that a single package 
 out of each lot of not more than 1,000 packages shall be taken as 
 representative of the whole. 
 
 With dry pigment, this package shall be opened by the inspector 
 and a sample of not less than 1 pound taken at random from the 
 contents. This shall be placed in a clean, dry metal or glass con- 
 tainer closed with a tight cover, sealed, marked, and sent to the 
 laboratory. With paste, whenever possible, an original unopened 
 container shall be sent to the laboratory, and when this is for any 
 reason not done, the inspector shall determine by thorough testing 
 with a paddle or spatula whether the material meets the requirements 
 regarding not caking in the container. See VI, 3, (a). Heshall then 
 thoroughly mix the contents of the container and draw a sample of 
 not less than 1 pound. This sample shall be placed in a clean, dry 
 metal or glass container, which it must nearly fill. The container 
 shall be closed with a tight cover, sealed, marked, and sent to the 
 laboratory for test with the inspector’s report on caking. The in- 
 spector should have a portion of the mutually agreed upon sample 
 of the dry pigment, paste in oil, or paste in japan, as may be called 
 for in the contract. Any delivery that is obviously different in color 
 than the mutually agreed upon sample, or in case of paste that is 
 badly caked in the container, shall be rejected by the inspector with- 
 out sending a sample to the laboratory. | | 
 
4 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 When requested, a duplicate sample may be taken from the same 
 package and delivered to the seller, and the inspector may take a 
 third sample to hold for test in case of dispute. 
 
 ~ lal 
 
 (2) Mass Cotor.—Weigh 1 g each*of sample and the mutually 
 agreed upon standard and rub up separately on a glass plate or stone 
 slab, using the same amount of the same linseed oil in each case. 
 Rubbing up (mixing with oil) is best done with a muller and should 
 be such that no lumps remain and each lot receives the same amount 
 of rubbing. Place portions of each side by side on a clear strip of 
 glass, turn the glass over and compare the colors. If there is a differ- 
 ence in color the delivery does not meet the specification. 
 
 (}) Cuaracter or Tint AND TinTING SrrencTH.— Weigh accu- 
 rately on a counter-poised watch glass about 0.02 g of the sample 
 and one hundred times as much dry zinc oxide and transfer to a 
 large glass plate. Add 0.7 cc of clear raw linseed oil (measure from 
 a burette) and mix with a clean steel (not nickel plated) spatula 
 until the mass appears to be homogenous. Wipe off the spatula on 
 the glass plate and on the rubbing surface of the glass muller. Grind 
 the paste with a circular motion fifty times with the muller, using a 
 uniform pressure. Gather up the paste with the spatula and grind 
 again fifty times with the muller. Repeat the operation once more. 
 Gather up the paste with the spatula and set aside. Using the stand- 
 ard mutually agreed upon in place of the sample, duplicate the above 
 procedure. Stir each of the pastes with clean spatulas and transfer 
 portions to a microscope slide, quite close together and draw a spatula 
 across both so as to make them meet in a line. Compare the colors 
 on both sides of the glass. If the sample differs from the standard 
 in tone; that is, if it shows more reddish yellow or a more greenish 
 yellow than the standard it does not meet the specification in character 
 of tint. If it shows the same character of tint and the rub out is as 
 dark or darker than the standard, it meets the specification im tinting 
 strength. If it shows the same character of tint and the rub out is 
 lighter than the standard it does not meet the specification in tinting 
 strength. ION 
 
 (c) Coarse Particies.—Dry in an oven at 105 to 110° C., a No. 
 325 sieve, cool, and weigh accurately. Weigh 10 g of the sample, 
 transfer to a mortar, add 100 cc of water, thoroughly mix by gentle 
 pressure with the finger to break up all the lumps, and wash through 
 the sieve with a gentle stream of water, stirring gently with a camel’s 
 hair brush until nothing more passes through the sieve. Dry the 
 sieve at 105 to 110° C. for one hour, cool, and weigh. From the 
 increase in weight of the sieve and the weight of sample calculate the 
 percentage of coarse particles, 
 
 2. LABORATORY EXAMINATION, DRY PIGMENT 
 
SPECIFICATION FOR CHROME YELLOW 5 
 
 (d) Oreantc Cotors or Laxes.—Test the pigment successively 
 with hot water, 95 per cent alcohol and chloroform. If the solutions 
 should remain colorless, organic colors are probably absent, but if 
 organic colors resistant to the above reagent are suspected, other 
 tes ~may be applied and it may be necessary to follow methods 
 
 ven in such books as Tests for Coal Tar Colors in Aniline Lake, 
 py Zerr and Mayer; A Systematic Survey of Organic Coloring 
 Matters, by Schultz and Julius; Identification of Pure Organic Com- 
 pounds, by Mulliken. 
 
 (¢) Marrer SotusLe In Water.—Transfer about 2.5 ¢ (accurately 
 weighed) to a 250 cc graduated flask. Add 100 cc distilled water and 
 boil for five minutes. Allow to cool, fill to mark with distilled water, 
 mix thoroughly and allow to settle. Decant through a dry filter and 
 discard the first 25 cc of filtrate. Transfer 100 cc of the remaining 
 clear filtrate to a weighed dish, evaporate to dryness, heat for one hour 
 at 105 to 110° C., cool, weigh, and compute percentage of matter 
 soluble in water. 
 
 (f) Water and OrHer VouaTiLeE Matrer.—Heat about 2 g, 
 accurately weighed, in a tared dish or weighing bottle for three 
 hours at 105 to 110° C., cool and weigh. Compute loss in weight 
 as water and other volatile matter. 
 
 (g) INsotusLE Marrer.—Treat an accurately weighed portion of 
 about 1 g with 25 cc of concentrated hydrochloric acid and boil for 
 from 5 to 10 minutes in a covered beaker, adding about 6 drops of 
 alcohol, 1 at a time, to the boiling liquid. Dilute to 100 ce with hot 
 water and boil for from 5 to 10 minutes. Filter the hot solution (if 
 insoluble matter is present) and wash with boiling water till wash- 
 ings are free from lead and chlorine. Ignite, weigh, and compute 
 percentage of insoluble matter. 
 
 (h) Oruer Impurities.—If careful qualitative analysis shows 
 absence of all bases other than lead, as will generally be the case, no 
 further examination will be necessary. If other bases are found, 
 determine by appropriate methods.’ 
 
 (i) CaucunaTIon or ToTaL oF ALL SussTaNces OTHER THAN 
 Compounps or Leap.—Add together the percentages of matter 
 soluble in water (VI, 2, (e)), water and other volatile matter (VI, 2, 
 (f)), insoluble matter (VI, 2, (g)), and other impurities (VI, 2, (/)). 
 
 3. LABORATORY EXAMINATION, PASTE IN OIL 
 
 (a) Caxine In ContTarneR.—When an original package is received 
 in the laboratory, it shall be weighed, opened, and stirred with a 
 stiff spatula or paddle. The paste must be no more difficult to break 
 up than a normal good grade of similar material. The paste shall 
 finally be thoroughly mixed, removed from the container, and the 
 
 1See A. S. T. M. standards D 126-23. 
 
7 
 oe J 
 6 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 container wiped clean and weighed. This weight subtracted from the 
 weight of the original package gives the net weight of the contents, 
 A portion of thoroughly mixed paste shall be placed in a clean con- 
 tainer and the portions for the remaining tests promptly weighed 
 out. 
 
 (6) Cotor.—Place portions of the sample and of the standard 
 mutually agreed upon side by side on a clean strip of glass. Turn 
 the glass over and compare the colors. If there is a difference in 
 color the delivery does not meet the specifications. 
 
 (c) CHaracrrer oF Tint aND Tintine StrRENGTH.—Weigh accu- 
 rately about 0.03 g of the thoroughly stirred paste (weighing by 
 difference and recording exact weight). Transfer to a large glass 
 plate. Add to this 100 times as much dry zine oxide (accurately 
 weighed). Proceed as in VI, 2, (6). 
 
 (d) CoaRsE PARTICLES AND Brennen —Dry in an oven at 105 to 110° 
 a No. 325 sieve, cool, and weigh accurately. Weigh an amount of 
 paste containing 10 g of pigment (see VI, 3, (g)), add 100 ce of kero- 
 sene, mix thoroughly, and wash through the sieve using kerosene, 
 but otherwise follow VI, 2, (c)). 
 
 (¢) WATER AND Baden Vovatine Marrer. —Weigh accurately 
 from 3 to 5 g of the paste into a tared flat-bottom dish about 8 cm 
 in diameter, spreading the paste over the bottom, heat at 105 to 
 110° C. for three hours, cool and weigh. 
 
 (f) Mrxine witH Linsgep Orut.—Place 100 g of the ae in a 
 cup. Add 50 cc raw linseed oil slowly with careful stirring and 
 mix with a spatula or paddle. The resulting mixture must be smooth 
 and of good brushing consistency. 
 
 . (g) PERCENTAGE oF PigmentT.—Weigh accurately about 15 g of 
 ins paste in a weighed centrifuge tube. Add 20 to 30 cc of “extrac- 
 tion mixture’’ (see Reagents), mix thoroughly with a glass rod, wash 
 the rod with more of the extraction mixture, and add enough of 
 the reagent to make a total of 60 cc in the tube. Place the tube in 
 the container of a centrifuge, surround with water, and counterbalance 
 the container of the opposite arm with a similar tube or a tube with 
 water. Whirl at a moderate speed until well settled. Decant the 
 clear supernatant liquid, repeat the extraction three times with 40 
 cc of extraction mixture. 
 
 After drawing off the extraction itches det Be tube i in a banker 
 of water at about 80° C. or on top of a warm oven for 10 minutes, 
 then in an oven at 105 to 110° C. for two hours. Cool, weigh, and 
 calculate the percentage of pigment. Grind the pigment to a fine 
 powder, pass through a No. 80 sieve to remove any skins, and bee 
 serve in a stoppered bottle. 
 
 (h) Preparation or Farry Acips.—To about 25 g of the taal 
 in a porcelain casserole, add 15 cc of aqueous sodium hydroxide (see 
 
SPECIFICATION FOR CHROME YELLOW 7 
 
 Reagents, and 75 cc of ethyl alcohol, mix and heat uncovered on a 
 steam bath until saponification is complete (about an hour). Add 
 100 cc of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
 10 ce in excess), boil, stir, and transfer to a separatory funnel to which 
 some water has been previously added. Draw off as much as pos- 
 sible of the acid aqueous layer, wash once with water, then add 50 
 ec of water and 50 cc of ether. Shake very gently with a whirling 
 action to dissolve the fatty acids in the ether, but not so violently 
 as to form an emulsion. Draw off the acqueous layer and wash the 
 ether layer with one 15 cc portion of water and then with 5 cc portions 
 of water until free from sulphuric acid. Then draw off the water 
 layer completely. Transfer the ether solution to a dry flask and 
 add 25 to 50 g of anhydrous sodium sulphate. Stopper the flask 
 and let stand with occasional shaking at a temperature below 25° 
 C. until the water is completely removed from the ether solution, 
 which will be shown by the solution becoming perfectly clear above 
 the solid sulphate. Decant this clear solution, if necessary, through 
 a dry filter paper into a dry 100 cc Erlenmeyer flask. Pass a rapid 
 current of dry air (pass through a CaCl, tower) into the mouth of the 
 Erlenmeyer flask and heat to a temperature below 75° C. on a dry, 
 hot plate until the ether is entirely driven off. 
 
 It 1s wnportant to follow all of the details, since ether generally con- 
 tains alcohol, and after washing with water always contains-water. It 
 is very difficult to remove water and alcohol by evaporation from fatty 
 acids, but the washing of the ether solution and subsequent drying with 
 anhydrous sodium sulphate removes both water and alcohol. Ether, in 
 the absence of water and alcohol, is easily removed from fatty acids by 
 gentle heat. 
 
 The fatty acids prepared as above should be kept in a stoppered 
 flask and examined at once. 
 
 (() Test ror MINERAL OIL AND OTHER UNSAPONFIABLE MaTrEr.— 
 Place 10 drops of the fatty acid (2) in a 50 cc test tube, add 5 cc of 
 alcoholic soda (see Reagents) boil vigorously for five minutes, add 
 40 cc of water, and mix; a clear solution indicates that not more than 
 traces of unsaponifiable matter are present. If the solution is not 
 clear, the oil is not pure linseed oul. 
 
 (7) Iopins Numsper or Farry Acips.—Place a small quantity 
 of the fatty acids (A) in a small weighing burette or beaker. Weigh 
 accurately. Transfer by dropping from 0.09 to 0.15'g into a 500 cc 
 bottle having a well-ground glass stopper, or an Erlenmeyer flask 
 haying a specially flanged neck for the iodine test. Reweigh the 
 burette or beaker and determine the amount of sample used. Add 
 
8 CIRGULAR OF THE BUREAU OF STANDARDS 
 
 10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
 10 cc chloroform to each of two empty bottles like that used for the 
 sample. Add to each bottle 25 ce of the Wijs solution (see Reagents) 
 and let stand with occasional shaking for one hour in a dark place at 
 a temperature of from 21 to 23° C. Add 10 ce of the 15 per cent 
 potassium iodide solution and 100 cc of water, and titrate with stand- 
 ard sodium thiosulphate, using starch as indicator. The titrations 
 on the two blank tests should agree within 0.1 cc. From the differ- 
 ence between the average of the blank titrations and the titration on 
 the sample and the iodine value of the thiosulphate solution, caleu- 
 late the iodine number of the sample tested. (lodme number is 
 centigrams of iodine to 1 g of sample.) If the iodine number is less 
 than 175 the oil does not meet the specification. 
 
 (c) EXAMINATION OF ExtTRacTED Pigmmnt.—Apply tests VI, 2, 
 (d); VI, 2, (e); VI, 2, (g); V1, 2, (2); and VI, 2, (@). 
 
 4, LABORATORY EXAMINATION, PASTE IN JAPAN 
 
 (a) CaxInG IN ConTAINER.—Apply test VI, 3, (a). 
 
 (6) Cotor.—Apply test VI, 3, (6). 
 
 (c) Cuaracter or Tint and TintiInc Strenctu.—Make test in 
 a manner similar to VI, 3, (c), except that on account of the volatile 
 matter in japan pastes it is not easy to weigh exact amounts. For 
 weighing, the materials should be placed in a wide-mouth stoppered 
 weighing tube along with a short spatula or spoon. After weighing 
 the whole, transfer with the spatula or spoon about 0.03 g to the 
 glass plate, return spatula or spoon to weighing bottle, insert stopper, 
 and again weigh. (To avoid trouble due to drying while weighing 
 the zine oxide cover the paste with about half of the oil to be later 
 used.) The difference in weight gives the weight of material taken. 
 Then weigh one hundred times this weight of zine oxide and proceed 
 as in VI, 2, (6). 
 
 (d) Coarse Particues anp Sxins.—Follow method gives in 
 V1; 35d 
 
 (e) VouatiteE Marrer.—Follow method VI, 3, (e) with the sisi 
 
 cautions regarding weight of sample given in VI, 4; (c). 
 — (f) Mrxine wirn Turpentine anp Dryine Txsts.—Place <bot 
 100 g of the paste in a cup and add turpentine slowly from a burette 
 while thoroughly mixing with a spatula or paddle. The paste 
 should readily break up and form a paint of brushing consistency. 
 Note the volume of turpentine required. This will vary somewhat, 
 but, in general, about 50 cc will suffice. Thoroughly stir this paint, 
 strain through a No. 100 sieve and apply by brushing to a clean 
 metal panel held in a vertical position. Apply the paint to only a 
 
SPECIFICATION FOR CHROME YELLOW 9 
 
 part of the panel, leaving a margin of at least 2.5 cm (1 inch) of 
 unpainted metal around the painted portion. It is best to use a 
 camel’s-hair brush for this painting. Allow the panel to stand in a 
 vertical position in a well-ventilated room at room temperature 
 (70 to 90° F.) for 1 hour. The film should be flat, of extremely fine 
 and smooth texture, uniform as regards color and finish and must be 
 hard enough to stand light rapid rubbing with the finger without 
 being removed. After a total of five hours drying, a brush coat of 
 Damar varnish (Damar resin cut in turpentine) shall be applied over 
 the entire surface of the panel. Any softening or raising of the flat 
 coat or any separation of color by this varnishing operation is cause 
 for rejection. In case of dispute on this drying test due to atmos- 
 pheric conditions, and umpire tests are necessary such tests shall be 
 made in a well-ventilated room maintained at a temperature of 70° F. 
 and relative humidity of 65 per cent saturation. 
 
 (g) Percentace or Picment.—Using the precautions in weighing 
 sample given in VI, 4, (c) follow method given in VI, 3, (9). 
 
 (hk) Examination oF Exrracrep Piement.—Apply tests VI, 2, 
 (d); VI, 2, (e); VI, 2, (g); VI, 2, (2); and VI, 2, (@). 
 
 5. REAGENTS 
 
 (2) Extraction Mrxturs.— 
 
 10 volumes ether (ethyl ether). 
 6 volumes benzol. 
 
 4 volumes methyl alcohol. 
 
 1 volume acetone. 
 
 (6) Aquzous Soptum Hyproxipr.—Dissolve 100 g of sodium 
 hydroxide in distilled water and dilute to 300 cc. 
 
 (c) Auconotic Sopium HypRroxIpDE Sotution.—Dissolve pure 
 sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
 about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 
 the clear liquid into another bottle and keep well. stoppered. This 
 solution should be colorless or only slightly yellow when used, and it 
 will keep colorless longer if the alcohol is previously treated with 
 sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
 15 days and then distilled. 
 
 -(d) Porasstum lopIpE SotutTron.—Dissolve 150 g of potassium 
 iodide free from iodate in distilled water and dilute to 1,000 ce. 
 
 (e) Wiss Sotution.—The preparation of the iodine monochloride 
 solution presents no great difficulty, but it should be done with care 
 and accuracy in order to obtain satisfactory results. There shall be 
 in the solution no sensible excess either of iodine or more particu- 
 larly of chlorine over that required to form the monochloride. This 
 
10 CIRCULAR OF THE BUREAU OF STANDARDS 
 
 condition is most satisfactorily attained by dissolving in the whole 
 of the acetic acid to be used the requisite quantity of iodine, using 
 gentle heat to assist the solution, if it is found necessary. Dissolve. 
 iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
 and is free from reducing impurities in the proportion so that 13 ¢ 
 of iodine will be present in 1,000 ce of solution. Set aside a small 
 portion of this solution while pure, and pass dry chlorine into the 
 remainder until the halogen content of the solution is doubled. 
 Ordinarily it will be found that by passing the chlorine into the main’ 
 part of the solution until the characteristic color of free iodine has 
 just been discharged, there will be a slight excess of chlorine which is 
 corrected by the addition of the requisite amount of the unchlorinated 
 portion until all free chlorine has been destroyed. A slight excess of 
 iodine does little or no harm, but excess of chlorine must be avoided, 
 
 (f) Sranparp Sopium TuiosutpHate SoLtutTion.—Dissolve pure 
 sodium thiosulphate in distilled water (that has been well boiled to 
 free it from carbon dioxide) in the proportion of 24:83 g of erystal- 
 lized sodium thiosulphate to 1,000 ce of the solution. It is best 
 to let this solution stand for about two weeks before standardizing. 
 Standardize with pure resublimed iodine.? This solution will be 
 approximately decinormal, and it is best to leave it as it is after 
 determining its exact iodine value, rather than to attempt to adjust 
 it to exactly decinormal. Preserve in a stock bottle provided with 
 a guard tube filled with soda lime. | 
 
 (g) StarcH So.tution.—Stir up 3 g of potato starch or 5 g of 
 soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
 300 to 400 cc of boiling water, and boil the mixture until the starch is 
 practically dissolved, then dilute to 1 liter. 
 
 VII. PACKING OF SHIPMENTS 
 
 Packing shall be in accordance with commercial practice unless 
 
 otherwise specified. 
 VIII. NOTES 
 
 There are very many different hues and shades that can with 
 equal exactness be called chrome yellow. The selection of the one 
 desired is entirely a matter of taste. There is no practical method 
 of getting the color desired, except that of having it match in color, 
 character of tint, and tinting strength the sample mutually agreed 
 upon. The composition requirements of the specification are of only — 
 secondary importance. 
 
 1 Treadwell-Hall, Analytical Chem. 2, 6th ed. p. 551. 
 
SPECIFICATION FOR CHROME YELLOW 1] 
 
 All purchasers and users of specification paint materials should 
 consult Bureau of Standards Technologic Paper No. 274, entitled 
 “Use of United States Government Specification Paints and Paint 
 Materials.’’ Material covered by this specification is not discussed 
 
 in that publication, but the information contained therein will 
 nevertheless be of value. 
 
 ADDITIONAL COPIES 
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