Pe Sot 5 ona tne tape be Ok ae aa eeteris . ; Bg a op RS ROE Fy ge or eh Ba OA ROR Ay be 2 wee ae lasipeeete Segoe etsy erent tom ee eee gere se eer ee pees ee =. ood Cth een at ney oF : ae 5 ; me Ay se x ve po - a é . am - SS Sa ee oie 4 = - 4 <—¥- ; “ : ‘ : t Peak sie ’ : ~ Ss . = - > " . ee ee eee hap Raper, rere " 7 = iain . . zi : bs 4 e: Seok nibs a aa oeee z et Te he o ES Pee ee ee Oe cagpadyinaliathe ro Pe ; er a tee Pilg. Gn et Ae et ae Pp yn a a ae fF ne Safa I ip mama neyo ere -s Se a in AD aE FN pate gh Sete PORE Pee yen re - . na Stn tet mente: Int Seeger si * ~ ~ Paes ee s oe ae ee ath cities Pp at * ome a aot cg ars iZn= ne ets " hE tS A Ge ee hy ee sg Ne Sing openly tm My » * = ty Phot pe: Z Sel a on a ress ar in _- i 2 Ee ee ~ « _— > _ main i a hae hee ae we anneins (onoreen ray ~~ = - ame ow “= - ne aw ~ = a ~ eee a eae eae. = * : -* - . - , ve A agarose. bas * — - aaews reuri oe . a Pane tein? caer? . < eee ed Le awn mr ~F_ars rome a a m4 oe » et ae oo stm. ret : na pth St tires tee ae -- eee atten a er Re ~~ = nf i ~ er “sd , iim : eee ee ts pple noe ae =e ae Male ain mn vers = ee — ph nF i cy on Biota heer ee een, Meet Seo £ @ PE OS eer ry ‘ iJ f ’ i ~ » : “wi rs 7 1 ¥¢ oe ‘4 : As ria ab THE CHEMISTRY AND TECHNOLOGY OF PAINTS BY MAXIMILIAN TOCH Disc ch. CS-i-RiP Ss. CHE: Vice President, Toch Brothers, Inc. Author of ‘‘Materials for Permanent Painting”’ “How to Paint Permanent Pictures,’ etc. Formerly Professor Industrial Chemistry, Cooper Union, New York Honorary Professor Industrial Chemistry, Pekin, China THIRD EDITION, REVISED AND ENLARGED NEW YORK D. VAN NOSTRAND COMPANY EIGHT WARREN STREET 1925 COPYRIGHT, 1007, 19010.1702,5 36 D. VAN NOSTRAND COMPANY All rights reserved, including that of translation into the Scandinavian and other foreign languages THE*PLIMPTON:PRESS NORWOOD:MASS:U°:S°A THE GETTY CENTER LIBRARY PREFACE TO FIRST EDITION Tue difficulty which I encountered in writing this book was not how much to write but how much to omit, for I found on compiling my notes that I could very easily have made two volumes, each larger than the present one, and still would not have covered the ground thoroughly. It is for this reason that I have omitted many of the pigments which are rarely used, and have paid no attention whatever to the pigments which have gone out of use. I have not considered it desirable to use any space in this book with extended repetition of matter that can be found in other books of reference, for I have so much matter which is the result of original research that very few references are cited. This being the first book ever written on the subject of mixed paints, I am cognizant of the fact that there are many matters in it which I shall have to alter in future editions, and many subjects upon which I shall have to enlarge It must be borne in mind that mixed paint is demanded by a progressive civilization and that there are no two manufacturers who make identically the same mixtures. As time changes, the progressive manu- facturer alters his formulas, and an indication of this is that the original mixed paints were mostly emulsions and soap solutions, whereas today the tendency is toward purity and improvement, and one manufacturer tries to outdo the other in making a paint that will last, the ideal paint, however, being never reached. lil iv PREFACE TO FIRST EDITION This volume is intended for the student in chemistry who desires to familiarize himself with paint, or the engineer who desires a better knowledge of the subject, or for the paint manufacturer and paint chemist as a work of reference. It is not intended for those who have no previous knowledge or training in the subject. Some of the chapters in this book are taken from my lectures delivered at various universities, and others are extracts from lectures delivered before scientific bodies. One of the objects which I have had in view during the entire time I have been writing this book is to familiarize the student in chemistry, or the post-graduate, with the science and technology of modern paints, so that in a very short time the chemist unfamiliar with the subject may obtain sufficient knowledge to make a reasonable examination of paint. The chapter on linseed oil illustrates this, and my researches and theories on the difference between raw and boiled linseed oil are here published for the first time. From the formulas and disquisition on the subject it can be easily seen that if raw linseed oil be taken as a standard nearly all comparisons fail if boiled linseed oil is under examination. 320 Firth AVENUE NEw YORK, 1907 Pee aCe TO, SECOND EDITION SINCE the first edition of this book was published the efforts of a large number of technical men working in this field have resulted in very important advances both in the production of new pigments, oils and special paints and in the scientific elucidation of many obscure phenomena in paint technology. Improvements have also been made in the method of manufacture as well as in the quality of many of the older pigments. Advances have also been made in the discovery and utilization of a number of oils which have not heretofore found extended use in the paint trade. These important advances have necessitated rewriting most of the book and the addition of new matter to the ex- tent of doubling its size. Some of the important additions which may be worthy of mention are, standard specifica- tions for pigments and oils; new special paints and driers; the theory of corrosion of iron and steel and its prevention as well as the action of fungi on paints; the important sub- ject of the hygiene of workmen; detailed methods of analy- sis of paints and paint materials as well as tables of constants of such materials. | Undoubtedly the chemical manufacturer and the chemical student who intends to become proficient in paint chemistry will find it essential to read a great deal of the past as well as the current technical literature of the subject, but it is the hope of the author that this book will give the student a comprehensive survey of the progress already made and furnish a foundation for further improvement. MAXIMILIAN TOCH 320 FirtH AVENUE New York July, 1916 v PREFACE TQ THIRD EDITION SO many investigations have been made since 1917, and so many new materials have been added to the list of pigments and oils, that it has become necessary to rewrite the second edition of ‘*The Chemistry and Technology of Paints” and bring it up to date. Our viewpoint on China Wood Oil has been largely changed, due primarily to investigations of the growth of the tung oil tree and the collection and expression of the seeds, and for the further reason, that the transplantation of the tung oil tree on a large scale in the United States has given us an oil which differs materially from that which we have considered standard China Wood Oil. Perilla Oil although not yet used in very large quantities will probably become an important factor in the paint and varnish industry. 110 HAST 42ND ST. New YorkK CITY September, 1925 MAXIMILIAN TOCH I acknowledge with thanks the valuable assistance which I re- ceived from my associates, Dr. T. T. Ling, Dr. V. P. Krauss and Mr. Ralph T. Mayer. I am greatly indebted to my personal assistant, Dr. T. T. Ling, Mr. William M. Taylor of the Chemical Division of the Bureau of Foreign and Domestic Commerce, for his excellent article on China Wood Oil, No. 125, Julean D. Arnold, Commercial Attaché, Peking, and Consul General Heinzelmann at Hankow. I am indebted to Mess. L. C. Gillespie & Sons for three of the illustrations. CONTENTS PREFACE TO First EDITION PREFACE TO SECOND EDITION. INTRODUCTION . . CHAPTER 1 THE MANUFACTURE OF MIXED PAINTS CHAPTER II THE WHITE PIGMENTS. White Lead. — Sulphate of seh Becca White eae — Ozark White. — Zinc Oxid. — Zinox. — Lithopone. — Titanium White. — Antimony Oxid. CHAPTER IIT THE Oxips oF LEAD Litharge. — Red Lead. — Blue eae CHAPTER IV THE INORGANIC RED PIGMENTS. Venetian Reds. — Indian Red. CHAPTER V THE YELLOW PIGMENTS American Yellow Ochre. — French Yellow unre oe Rae cae — Chrome Yellow. — Chromate of Zinc. — Yellow Iron Oxids. — Cadmium Yellow. — Antimony Sulphide. — Arsenic Sulphide. CHAPTER SSVI THE BRown PIGMENTS American Burnt Sienna. — Italian ee eare. — Raw and Burnt Umber. — Burnt Ochre. — Prince’s Metallic or Princess Mineral Brown. — Vandyke Brown. CHAPDER VII THE BLUE PIGMENTS . Ultramarine Blue, — Artificial epi Blue. — Pan Blue. vil ill 23 52 62 67 75 82 vill CONTENTS CHAPTER VIII THE GREEN PIGMENTS Chrome Green. — Ghisucin Oxid. Bee l Chrome Oxid. — Verte Antique (Copper Green). CHAPTER IX THE BLAack PIGMENTS Lampblack.— Carbon Black.— BG raniitee es Charepall 7 Vi ine > Blade — Coal.— Ivory Black.— Drop Black.— Black Toner. — Benzol Black. — Acetylene Black. — Mineral Black. CHAPTER X THE INERT FILLERS AND EXTENDERS Barytes. — Artificial Barium Sulphate. — Bare Catone Sy Silica. — Infusorial Earth. — Kieselguhr. — Fuller’s Earth. — Clay. — Asbestine. — Asbestos. — Calcium Carbonate. — White Mineral Primer. — Marble Dust. — Spanish White. — Artificial Calcium Carbonate. — Gypsum. CHAPTER XI LAKES AND TONERS . ‘ Red Lakes. — Para one See pate Rac terhT >: or Alizarin Lake. — Other Lakes. — Oil Soluble Colors. CHAPTER XII MIxeEp PAINTs . Anti-fouling and Ship’ S Botton Points <= ~ Concteea or Pevctiaes Cement Paints. — Paint Containing Portland Cement. — Damp- Resisting Paints. — Enamel Paints. — Flat Wall Paints. — Floor Paints. — Shingle Stain and Shingle Paint. CHAPTER’ Xitil LINSEED OIL . Linseed Oil. Pee anette ARBOR Socios for Testing g Materials for Linseed Oil. — U. S. Navy Department Specifica- tions for Linseed Oil. — Stand Oil. — Japanner’s Prussian Brown Oil. — Perilla Oil. CHAPTER XIV Cu1nA Woop OIL é Production of Wood Oil. - — Rennes — Se ran — Heat Tests. — Quality Tests. — American Production. — Deodoriza- tion. — Lumbang Oil. — Stillingia Oil. CHAPTER XV SovA BEAN OIL. go 95 108 140 146 164 IQI 225 CONTENTS CHAPTER XVI FisH OIL CHAPTER XVII MISCELLANEOUS OILS. Herring Oil;— Corn Oil. CHAPTER XVIII TURPENTINE . eatrpenune’ <= Wood Turcenting. a Seeehn Srecneatione een can Society for Testing Materials for Turpentine. — U. S. Navy Department Specifications for Turpentine. CHAPTER XIX Pine OW .. CHAPTER XX BENZINE CHAPTER XXI ~ ‘TURPENTINE SUBSTITUTES . Benzo1. — Toluol. — Xylol. — Solvent Napntha. CHAPTER XXII COBALT DRIERS CHAPTER XXIII COMBINING MEDIUMS AND WATER Combining Mediums. — Water in the Cseitiah of Mixed Pune — Emulsifiers. — Emulsions. CHAP LER XXIV FINE GRINDING CHAPTER XXV THE INFLUENCE OF SUNLIGHT ON. PAINTS AND VARNISHES . CHAPTER XXVI PAINT VEHICLES AS PROTECTIVE AGENTS AGAINST CORROSION CHAPTER XXVII THE ELECTROLYTIC CORROSION OF STRUCTURAL STEEL. CHAPTER XXVIII PAINTERS’ HYGIENE 1X 243 250 268 273 277 292 204 301 BTT 319 xX CONTENTS CHAPTER XXIX THE GROWTH OF FUNGI'ON PAINT . CHAPTER XXX PHYSICAL EXAMINATION AND TESTING OF PIGMENTS CHAPTER XXXI ANALYSIS OF PAINT MATERIALS . White Lead. — Basic Lead quiphates a Zinc Lee S27 Oxid. — Lithopone. — Red Lead and Orange Mineral. — Iron Oxids. — Umbers and Siennas. — Mercury Vermilion. — Chrome Yel- lows and Oranges. — Chrome Greens. — Prussian Blue. — Ultramarine. — Black Pigments. — Graphite. — Blanc Fixe. — Whiting. — Gypsum or Calcium Sulphate. — Silica. — Asbes- tine. — Clay. — Barytes. — Barium Carbonate. — Mixed White Paints. — White Pigments. — Paints. — Rosin. — Rosin Oils. —= Oils tet Lc: APPENDIX BOILED OILS — CHARACTERISTICS. REFRACTOMETRY . CONVERSION OF FRENCH sale. INTO oe eon AND MEASURE METRIC SYSTEM OF WEIGHTS AND Meee SPECIFIC GRAVITY OF VARIOUS MATERIALS SPECIFIC GRAVITY OF THE ELEMENTS . . Bory PouNDS OF OIL REQUIRED FOR GRINDING I00 Poem OF ee ce _ PASTE FROM VARIOUS PIGMENTS SPECIFIC GRAVITY OF VARIOUS WooDs THERMOMETER CONVERSION TABLES BIBLIOGRAPHY . INDEX 322 326 330 388 389 394 395 396 400 400 4OI 402 403 407 THE CHEMISTRY TECHNOLOGY OF PAINTS INTRODUCTION THE manufacture of mixed paints is_ essentially American, having been accredited to some enterprising New Englanders who observed that when a linseed oil paint was mixed with a solution of silicate of soda (water glass) an emulsion was formed, and the paint so made showed very little tendency to settle or harden in the package. Several lay claim to this discovery. The first mixed paint was marketed in small packages for home consumption and appeared about 1865. The addition of silicate of soda is still practised by a few manufacturers, but the tendency is to eliminate it as far as possible and to minimize as much as possible the use of an alkaline watery solution to keep the paint in suspension. The general use of zinc oxid has had much to do with the progress of mixed paint, for it is well known that corroded white lead and linseed oil settle quickly in the package, while zinc oxid keeps the heavier lead longer in suspension. Where only heavy materials are used, manufacturers are inclined to add up to 4 per cent of water. Under another chapter on “Water in the Composition of Mixed Paints,” page 286, this subject will be fully discussed. To the pigments are added many materials possessing but little body, hiding or covering property, which are I 2 INTRODUCTION known as inert fillers, and some of these, particularly the silicates of alumina and the silicates of magnesia, the various calcium carbonates, and silica itself, are used to counterbalance the heavy weight or the specific gravity of the metallic pigments; and whereas these inert fillers were formerly regarded as adulterants and cheapening agents, they are now looked upon as necessities, and the consensus of opinion among practical and many scientific investigators 1s that a compound paint composed of lead, zinc, and a tinting pigment, to which an inert material has been added, is far more durable than paint made of an undiluted pigment. The consuming public and the painter himself have not been sufficiently educated as yet to understand the merits of these diluents, and the paint manufacturer has been reticent in his statements regard- ing the use of various fillers. These facts account to a large degree for the opposi- tion to the use of such materials. When it is taken into consideration that within forty years the sale of mixed paints in the United States has grown to almost sixty million gallons per year (and the outlook is for a larger increase in the use of mixed paints), it is obvious that the demand is healthy, even though the manufacture of mixed paints has been directed or based largely upon empirical formulas. One of the railroads of the United States buys at this writing upward of one million dollars’ worth of paint material per year, a large share of this being mixed paints, or paint ready for the brush. Nearly all of the large manufacturing industries which use large quantities of paint are gradually altering their methods, so that their paint comes to them ready for application. In no case, to the best knowledge of the author, does a single one of these industries prescribe a single pigment with linseed INTRODUCTION 3 oil for general purposes, for it has been shown that a mixture of several pigments and a filler is superior from the standpoint of lasting quality and ease of application to a mixture of a single strong pigment and the vehicle. The structural iron industry, which has reached an enormous development in the United States, uses paints ready mixed with the one exception of red lead, which, in the old prescription of thirty-three pounds of red lead to one gallon of oil, cannot be prepared ready for the brush, for reasons which will appear in the proper chapter. The manufacture of agricultural implements, wagons, and wire screens can be cited as industries in which manu- facturers have within a very few years adopted the use of ready-mixed paints for their products. These paints are not brushed on, but are so scientifically made, and the relation between a vehicle and a pigment is so carefully observed, that large pieces of their products can be dipped into troughs and the paint allowed to drain. The surface is more evenly coated and the work done in far less time than would be required were it applied by means of the brush, as in former years. In view of all these facts, the prejudice on the part ot the general public and the trepidation of the manu- facturer are to blame for the unheralded knowledge of ‘ the constituents of mixed paints. There are many cases where materials which were once despised are regarded now as essential to the life and working quality of paint, and the attitude of the paint manufacturer must in the future be a frank and open admission of the com- position of his materials. If a paint is composed of a mixture of white lead, zinc oxid, and barytes, and it has been proved that a mixture of these three will outlast a mixture of either of the other two, there is no reason why a manufacturer of mixed paints shall not so state. 4+ INTRODUCTION New materials have come into use which have taken the place in a large degree for many purposes of the time-honored and useful white lead, and many mixed paint manufacturers have already begun to educate the public to the superiority of one material over another. It stands to reason, however, that the manufacturer of a raw material which has been in use for a very long time is going to refute as much as possible the statement made with regard to newer materials, and these dis- cussions tend to do good rather than harm. In the case of one of the large railroads, the speci- fications for a certain paint demand the use of over 70 per cent of inert filler, and if these inert fillers had no merit no railroad or large corporation would permit their use. These large corporations support chemical labora- tories and employ the best talent which they can engage. They continually experiment, and in their specifications the results of their experiments are obvious, and there- fore if a large corporation can state publicly not only what the composition of these paints shall be, but con- clude that such compositions are based upon the results of scientific investigation, the paint manufacturer can do likewise and stand back of his products, provided they be mixtures of various materials which time, science, and investigation have proved to be superior. Unfortunately, however, there are some manufactur- ers who have ‘‘hidden behind a play of words” and per- mit chicanery and finesse to enter into the description of their products; but fortunately some of them have seen the errors of their way, and already there is a ten- dency toward openness and candor with regard to their wares. There was a time, and it still exists in a measure, when substitutes for white lead were very largely sold, and misleading labels appeared on the packages; for INTRODUCTION 5 instance, a man would make a mixture of 80 per cent barytes and 20 per cent white lead, and would print on the label—‘‘The lead in this package is guaranteed absolutely pure,” followed by a commendation and guarantee that certain sums of money would be paid if the lead were not found to be pure. This, of course, is a moral fraud and an unfortunate play on the ambiguity of the language, and many of the manufacturers, in view of such unfortunate misstatements, are altering the names of their paste products, or lead _ substitutes, omitting the word “lead” entirely. Another unfortunate mistake is made when a manu- facturer makes a mixed paint and states on the label, “This paint is composed of pure lead, pure zinc, pure linseed oil, pure drier, and nothing else.”’ The analyses of the paint have proved that in addition to the “pure” products mentioned three gallons of water were added to every hundred gallons of paint in order to keep the paint in suspension, and that it had not been strained and therefore contained a large amount of dirt and for- eign matter. Ethics would clearly indicate that no manufacturer has a moral right to label his paint as being entirely pure and composed of four materials, when as a matter of fact an excessive quantity of water was added which destroyed in a large degree the value of the other materials. In another chapter the question of the percentage of water which may be contained in any paint will be thoroughly discussed. Three per cent is entirely excessive in an exterior linseed oil paint, and a manufacturer has no right, either morally or legally, to hide behind a misrepresentation of his paint when the paint is largely adulterated for the purpose of over- coming his ignorance in the manufacture. CHAPTER “I THE MANUFACTURE OF MIXED PAINTS THE modern methods of making mixed paint are ‘divided into two classes, depending upon the specific gravity and fineness of the raw material. One of the methods employed is to mix the raw material with sufficient linseed oil to form a very heavy paste, the proper tinting material being added during the process of mixing. ‘This paste is then led down from the floor on which it is made, into a stone mill and ground. Even when the mill is water-cooled, the mass frequently revolves at such a speed that the paste paint becomes hot. It is then allowed to run from the mill into a trough called the “cooler,” or is stored in barrels to be thinned at some later time. In case the operation is continuous and the paste is thinned at once, it passes from a stone mill to a mixer below which contains the requisite quantity of thinning material composed of oil, volatile thinner, and drier, where it is intimately mixed by means of paddles. It is then compared with the standard for shade, and if the tone should not be identical with the former mixing, either tinting material or pigment is added in sufficient amount to produce the proper shade. From the last mixer, known as the “liquid mixer,” the paint is drawn off and filled into packages, the final operation before allowing it to enter the package © being to strain it. This method has been used ever since mixed paints have been made. The majority of 6 THE MANUFACTURE OF MIXED PAINTS No. 1. A MILL ror PAstE GrinvDING 8 CHEMISTRY AND TECHNOLOGY OF PAINTS white paints, or paints of heavy specific gravity, are made in this manner. The paints of lower specific gravity, varnish and floor paints, are made differently. This method is really the reverse of the old-fashioned method, in that the liquid and pigment are placed in a mixer on an upper floor in the amounts necessary to produce the correct consistency. The paint is run down in a thin stream to the floor below into a mill known as the “liquid mill.” The liquid mills revolve very rapidly, the stones being flat. According to the best practice of making paste paints a grinding surface is supposed to be conical, although there is much difference of opinion on this subject. When the paint has run through the stones of a liquid mill, it comes out of a spout and is then ready for packing, due precaution being taken, however, to strain it twice, once as it passes down into the liquid mill and again as it flows out. There is much difference of opinion among paint-making mechanics as to the proper surface which a grinding surface shall present; for instance, the first depression in the stone of a mill is deep, tapering toward the edge, and is known as the “lead.” From the end of this ‘“lead”’ fine lines radiate toward the “periphery” of the stone. These are called the “drifts,” and the paints containing silica wear off the surface of even the hardest flintstone mills, so that in well-regulated factories a man is always employed sharpening the mills, and by the term “sharpening”’ is understood cutting out the “drifts” and “leads.” Not so many years ago paint mills were composed of either iron or steel, but in modern paint practice mills of this character have been abandoned, except for use as filling machines. They grind fairly fine when sharp, THE MANUFACTURE OF MIXED PAINTS No. 2. STANDARD LiquIp MILL. KENT. ge) CHEMISTRY AND TECHNOLOGY OF PAINTS but inasmuch as all silicious paint materials are harder than steel or iron they become dull in a very short time. Then again, the attrition grinds off small particles of iron, which affect all delicate tints more or less. The arrangement of the tanks and mills in the factory is of the greatest importance. Taking up first the second method of mixing paint already described, the liquid and white base are mixed in large, heavy cast- iron mixers, which are located on a platform high enough to discharge into a liquid mill. (See No. 4, Heavy Mixers.) The mixed material is ground through this mill and discharged from it into storage tanks situated con- veniently on a platform below the floor on which the mill is located, these storage tanks holding from 1500 to 2000 gallons of the ground product. From the stor- age tanks a pipe-line with its various branches carries the paint to tinting tanks placed at convenient dis- tances from the storage tanks, the latter being high enough to allow the paint, by gravity, to flow through pipes to the tinting mixers. This pipe-line is made of wrought iron, the usual diameter of which is 4 inches, - the joints being all flanged so that the pipes may be easily taken apart and cleaned. Underneath the storage tanks and close to the outlet is a master valve, so that the product in the tank may be shut off at any time and the flow cut out from the sys- tem of pipes. Opposite each tinting tank (these tanks should be in parallel rows and numbered to correspond to the tints that are to be made) a 2-in. branch pipe is connected to the 4-in. main, and each of these branches is furnished with a valve to control the discharge into the tinting mixers. The cast-iron mixers already men- tioned should be so arranged that two mixers work in THE MANUFACTURE OF MIXED PAINTS 8 & No. 3. Mitt OPENED FOR CLEANING — Note design of grooves on upper stone. 12 CHEMISTRY AND TECHNOLOGY OF PAINTS conjunction with one mill. The mill is of stone and known as a liquid or incased mill, the usual diameter being 30 to 36 inches. E BS oe earn Zaye SESS ae ASE TS ee, GL See TI TROBE SSG G i SEN EES OME BS SSIES GG aii mais \ TINTING TANKS eee: vue sabia Patri st : No. RTE MIXERS The storage tanks are made of sheet metal with heavy sheet-steel bottoms, and are furnished with a slowly revolving stirrer to keep the ground liquid agi- tated. The outlet of these tanks is of generous size and covered with a steel wire screen to prevent any foreign THE MANUFACTURE OF MIXED PAINTS No. 5. CHANGE-CAN PASTE Mixer— The can and the paddles revolve in opposite directions. Cooren — — JF. Ye — ara Lice 2 a Sy A coven Mice: YEE x ~~ (a: ih { {- t—T hor } |__| OLN GA / cases No. 6. rT | = = u ols ml hd Bp H 2 yp drt - THE MANUFACTURE OF MIXED PAINTS 15 matter such as chips of wood or like material from getting into the supply pipes. Fastened to the stirrer of these tanks is a wire brush which scrapes the surface of the screen in its rotation around the tank, thus keeping the holes of the screen free for the proper flow of the liquid. The tinting colors used in this process are usually ground through small stone mills of 15 in. or 20 in. diameter, and are stored in convenient portable receptacles. This method of liquid paint-making reduces the handling and labor cost to a minimum, the hardest work being done on the mixer platform where the dry pigment and the proper amount of liquid are first mixed. In a factory where the floors are not arranged so that the method already described can be carried through by gravity alone, it is possible and practicable to introduce a force pump, preferably of the rotary type, to make up for this deficiency. When this latter method is _ used, the cast-iron mixer and mill should remain in the same relative position as before, but the storage tank could be placed in any other part of a building and on the same floor as the liquid mill, but high enough to discharge by gravity into the tinting mixers. The ground pig- ment would then be discharged into a small tank situated at the foot of the mill, to which the rotary pump is attached. As this tank is filled with the ground product, the pump would force it through the proper pipe connection to the storage tank, the connection from the storage tanks to the tinting mixers being the same as in the first described process. The other method in use is to mix and grind the pigment in paste form, using the same style of mixer; but instead of a liquid mill a paste mill is used. Situated at the back of this paste mill, and close to the discharge scraper, is a steel tank of generous dimensions (usually 16 CHEMISTRY .AND TECHNOLOGY OF PAINTS 4TH FLOOR (eee | ae —S | eS eS a: l : THE MANUFACTURE OF MIXED PAINTS 17 soo gallons), into which the ground pigment is dis- charged. This steel tank is provided with a stirrer for mixing the ground pigment with the oil and other thin- ners that are added to it, in order to reduce it to a liquid form. It is then carried to the tinting tanks by a pipe-line on the same general plan as that heretofore described. One of the advantages of this plan is that this outfit can be used in a dual capacity, i.e. it can be used for the mixing of liquid paints after the plan described and, by changing the scraper from the back to the front of the mill, the outfit can be changed into a paste-grinding plant. Many paint factories are located in one-story buildings. In this case the steel thinning tank as described above is oe cece (een ee eae oo qiqusee—= ae ae x 8 Pulley jl ~\\ —=-=--6' ('----=+ ----------------]3!. §''------- ‘hohe Capacty pproximately 150 Lb/Sq. Ft. SN 20"High Leg Mill-----> ------7'. 6'"\------- CEG 7 YY No. 8 A SINGLE Story PAINT FACTORY furnished with casters, or lift trucks are used in order that it may be moved to a stationary paddle equipped with a propellor blade, the shaft of which may be raised vertically to allow the tank to be placed underneath. The mixer is placed on a platform just above and behind the mill, 18 CHEMISTRY AND TECHNOLOGY OFSPATH TS or if the building is not high enough, change can mixers are used and the heavy cans moved around by means of an overhead trolley track on which a chain fall travels. Containers for the finished paint are filled from the thinning tank which is generally about 125 gallons capacity and fitted with a gate at the botton for the purpose, by hoisting it with this tackle or by raising it on a portable elevator. One-story paint factories are always more or less of a make- shift nature and are only designed from necessity for financial reasons, as the enormous amount of waste motion, time and extra labor makes them very inefficient. PEBBLE MILLS The pebble or ball mill has come into use in recent years and because of its advantages is a most efficient means of grinding many types of paint, particularly those that do not require extremely fine grinding and the ones that contain dry ingredients requiring little grinding by reason of their soft texture. The mill consists of a revolving steel conde of rugged construction mounted on trunions and lined with burrstone. It is about half filled with flint pebbles and the sliding, rubbing and grinding action of these pebbles on each other and against the cylinder wall grinds pigment and vehicle into a uniform product. All the materials are loaded at once into an opening from the floor above or from a plat- form and the finished paint is filled into containers or pumped into storage tanks from a valve which is located opposite the filling cover. Pebble mills have many advantages over the older types of mill. Whenever the same result may be obtained in less time than by the use of flat stone or roller mills there is obviously a great saving. Labor is also saved by combining the three operations of mixing, grinding and THE MANUFACTURE OF MIXED PAINTS 1Q No. g. PEBBLE MILL SHOWING METHOD OF CHARGING 20 CHEMISTRY AND TECHNOLOGY OF PAINTS thinning, and in the slight attention the mill requires while in operation. There is little heating or evaporation and both the grinding room and the paint are kept cleaner. Although their makers recommend them for the manu- facture of almost every kind of paint and while they are capable of making most of them, they have by no means entirely supplanted the other types at the present time, most of their users preferring to limit them to certain varieties of paints and to continue the use of the older types for others. They cannot be employed where a stiff paste is required, as they will only make a semi-paste and they are not generally suitable for the production of small batches. The most efficient sizes are 6 to 8 feet or more in diameter having capacities of 400 to 1800 gallons of paint. A Pebble Mill cylinder may be considered as an elevator carrying the material to the top of an incline down which it will tumble with more or less speed according to the slope of the dump. In No. to shown above is indicated in black a wedge-shaped block of material ready to slide down and in No. 11 is shown the same wedge after falling. It is to be understood, however, that while these figures are theoretically correct as a basis of calculations, the actual outline of thick or dry material in the revolving cylinder will be about as indicated in No. 12 for the reason that the cen- trifugal force will be stronger at the circumference than near the center and because of the rebound and deflection at the bottom. In dropping the pebble has an accelerated movement so that its first contacts have less force than later ones which explains the greater pulverizing effectiveness of mills having large diameters as compared to mills of small diameter and also shows why mills must not be built so large as to have a destructive effect on the pebbles themselves. — Courtesy Paul O. Abbé, Inc. Copyright, 1924. THE MANUFACTURE OF MIXED PAINTS 21 No. 13. A ROLLER MILL 22 CHEMISTRY AND TECHNOLOGY OF PAINTS The size of pebbles varies in ratio to the capacity of the mill. Large mills have large pebbles and small mills have small pebbles. It must be taken into account that the attrition or grinding of paint is produced entirely by the impact of one pebble on another, so that if pebbles are too large, longer time is necessary in grinding, and if they are too small, the weight is insufficient. There is another point with regard to the pebbles which must always be taken into account. After a mill has run a year, the pebbles are very much reduced in size, for it is quite natural that the surface is abraded. For each charge of paint, the distribution of added silica from this cause is not very great but it is a factor just the same. ROLLER MILLS Roller mills are often used for the manufacture of mixed paints and enamels but their principal use is in the manufac- ture of printing inks. They are much more rapid than the flat stone mills but do not grind so fine, the paint being put through the mill several times to produce the same effect as that produced by one run through a burrstone mill. This multiple grinding is often accomplished by placing two or three such mills one above the other so that the paint flows directly from the outlet of one onto the rolls of the next. The mill usually consists of three steel rollers so mounted on supports that the paste, flowing in a continuous stream from a gate in the side of the mixer which is always mounted above the mill, drops between the first and second rollers, is ground between them and then goes between the second and third where it is scraped off by the delivery trough. The first and third rolls are often hollow, especially in the larger sizes, to allow for cooling by the circulation of water through them. In England they are more popular for paint grinding than they are here. THE PIGMENTS CHAPTER II THE WHITE PIGMENTS THE white opaque pigments used in making mixed paints are white lead, zinc oxid, sublimed white lead, leaded zincs, lithopone, and other zinc and_ lead pigments. Among the white leads there are several varieties; the principal ones, however, are the old Dutch process lead and the quick process lead, both of which are hydrated carbonates of lead. There are many varieties of zinc oxid made in the United States, depending largely upon the raw material. The grade made principally from spelter, according to the French process, is known in America as “Florence Red” and ‘“‘Green Seal Zinc.’”’ The seals on zinc indicate the whiteness of color, the green seal being the whiter. In Germany the colored seals extend to a greater range than in America, the green seal being the whitest, the Ted next, the blue next, the yellow next, and then the white. The New Jersey zinc oxids are made direct from the ore and are almost as pure as the zincs made from the metal, but they have a totally different tone, being much more of a cream color than the so-called French zincs. The Mineral Point zincs made in Wisconsin contain a varying percentage of sulphate of lead. The leaded 23 24 CHEMISTRY AND TECHNOLOGY OF PAINTS zincs of Missouri are analogous in composition to those of Mineral Point, but the percentage of sulphate of lead is much higher. Sublimed white lead is made in Joplin, Missouri, from Galena mineral, and will average 95 per cent oxysulphate of lead and 5 per cent zinc oxid. ‘This material has been largely superseded by a white known as Ozark White, which is described under that heading. Leaded zincs are similar to Ozarks. | Lithopone is a double precipitate of sulphide of zinc and sulphate of barium. These are the opaque white pigments used in the manufacture of mixed paints. It is not within the power of any man to say which one of these is the best, because under certain circumstances one material will outrank another, and long practice has demonstrated that no single white pigment material is as good as a mixture of various white pigments for mixed paint. The differences of opinion and conflicting reports that one hears con- cerning these raw materials are largely due to competi- tion among manufacturers. Whenever a new material is exploited a manufacturer of a tried and staple pig- ment naturally finds the defects in the new material and informs his salesmen to this effect. And so when a material finally succeeds and takes its place among the recognized list of pigments it has gone through all the hardships and vicissitudes possible. For two thousand years, more or less, there was no other white pigment than white lead. Within the life- time and memory of many a paint manufacturer in the United States all the pigments described in the beginning of this chapter have been born and have prospered. The great competitor of white lead is zinc oxid, and the weakness of white lead is the strength of zinc oxid, and WHITE PIGMENTS 25 vice versa. White lead, for instance, is a soft drier and zinc oxid is a hard drier. White lead finally becomes powdery; zinc oxid in its eventual drying becomes hard, and it is for these reasons that a mixture of zinc oxid and white lead forms such a good combination. On the other hand, it is regarded as a fact that a paint com- posed of an opaque white pigment in a pure or undiluted state should not be used, for experience and chemistry have both shown that an inert extender added in mod- erate proportions to the solid white pigment increases its wearing power, and when the surface finally needs repainting it presents a better foundation for future work. ‘Taking all of these facts into consideration, a paint manufacturer who combines experience with the teaching of chemistry is quite likely to produce a mate- rial that will add both to his reputation and his income. He certainly has a great advantage over the man who works entirely by rule of thumb. WHITE LEAD Formula, 2PbCO;:Pb(OH)2; Specific Gravity, 6.323 to 6.492 White lead is the oldest of all white paints, and prior to the middle of the last century it was the only white pigment in use with the exception of a little zinc and bis- muth. Within half a century quite a number of other white pigments have come into use, and only gradually have the defects of white lead become known. However, paint manufacturers in the United States are very large users of dry white lead, which, together with zinc, asbestine, and other inert materials, forms the bases or pigments of the mixed paints. There seems to be an antagonism against the use of white lead which apparently is unfounded, for, although white lead may have its 26 CHEMISTRY AND TECHNOLOGY OF PAINTS defects, there is no other white pigment which is 100 per cent perfect, and therefore it is only fair to give that time-honored material its proper due. White lead as a priming coat on wood, particularly when it contains more oil than should normally be used, cannot be ex- celled. The history of this pigment, its method of manu- facture, and the general uses to which it has been applied are so well known, and are generally given even in elementary text-books on chemistry, that it is not the author’s purpose to take up much space for this subject. Briefly stated, however, there are two processes for the manu- facture of white lead. One is called the Dutch process, which takes about ninety No. 14. Corropep Warre Leap— days and is a slow cor- Photomicrograph X250, of known : purity and composition. rosion of a buckle of lead in an earthenware pot in the presence of acetic acid. Carbonic acid from fermenting tan bark acts on the lead, converting the material into hydrated carbonate of lead. In the other, which is called the quick process, the acetic acid solution is directly acted upon by either carbonic acid gas or an alkaline carbonate salt. The old Dutch process is still much more largely used than the quick process, the resulting product being much more desirable from the practical standpoint. There are a number of other processes under a variety of names, but none of them differ very much from the so-called ‘quick process.”’ WHITE PIGMENTS 27 White lead is in great favor with the practical painter, not for its wearing quality, but principally for the free- dom with which it is applied. Although white lead is generally spoken of as a carbonate of lead, it is com- posed of approximately 69 per cent carbonate of lead, PbCO;, and 31 per cent of lead hydroxid, Pb(OH).. It is this lead hydroxid which combines quite rapidly with oil and forms an unctuous substance sometimes known as “lead soap.” White lead is variable in composition, the amount of hydroxid ranging from TRL hed Om Clee COOL tel Ty addition to this, during the process of manufac- ture of the old process leads and -aiter its) tinal washing, it is mixed with linseed oil while still in the wet state. The. oil having a greater affnity for the white lead than the water has, the latter is displaced. A -small per- centage of moisture adds to the free working quality of the paint made from white lead. (See ‘‘Water in the Composition of Mixed Paints,” page 286.) White lead is regarded as a poisonous pigment, and so it is, but this property should not condemn it for application to the walls of a house or for general paint purposes, because its toxic effect cannot be produced from a painted surface. Its poisonous quality is mani- fest to the workmen in the factories where white lead is made, and also to the painter who is careless in apply- ing it. The unbroken skin does not absorb lead very No. 15. OLp Process WHITE LEAD — Photomicrograph x250. 28 CHEMISTRY AND TECHNOLOGY OF PAINTS rapidly, but the workman inhaling lead dust, or the painter who allows a lead paint to accumulate under his finger nails, is likely to suffer from lead poisoning. In one or two factories where much white lead is ground, a small percentage of potassium iodide is placed in the drinking water. This overcomes any tendency toward lead poisoning, by reason of the fact that the soluble iodide of lead is formed in the system and the lead is thus flushed out through the kidneys. Charles Dick- ens, in one of his short stories called “A Bright Star in the East,” com- ments on the misery pro- duced in a certain white lead factory in London, and expresses the hope that American ingenuity would overcome the dan- gers which beset the men. In one of the largest white lead works in New York City lead poisoning does not occur, owing to the in- genuity and care exercised by the management. The ratio of oil necessary to reduce white lead to the consistency of paint can by no means be given in exact figures. The old Dutch process lead will take four and a half gallons of linseed oil to one hundred pounds of white lead ground in oil, in order to obtain a paint of maxi- mum covering property. The new process lead will take more oil than this, and in many instances up to six gallons to the one hundred pounds of white lead paste, which contains approximately 1;’'> gallons of linseed oil. On a mixed paint basis, 60 pounds of dry white No. 16. WuIte LEAD (new process) — Photomicrograph X250. WHITE PIGMENTS 20 lead will take 40 pounds of linseed oil to produce the correct ratio, but in addition four pounds of volatile thinner, such as benzine or turpentine, can be added to increase the fluidity and assist in the obliteration of brush marks. No general rule can be given for the per- centage of oil necessary, as temperature has much to do with this, but the difference in the amount of oil neces- sary to produce a good flowing paint during summer or winter can be approximately given as ro per cent, less vehicle being necessary in summer than in winter. White lead when exposed to the elements becomes chalky after a while and assumes a perfectly flat appear- ance which resembles whitewash, and comes off very readily on the hand. As long as there was no remedy for this there was no comment on the subject, but at the present time investigators have improved paint mixtures so that this defect is not so palpable as it was in former years. From many experiments made by the author the causes of the chalking of white lead may be sum- marized as follows: Normal lead carbonate which contains practically no hydroxide and which is so often confused for white lead is crystalline material having little or no hiding power, and is composed entirely of boat-shaped crystals. When litharge is carbonated under pressure, with carbon dioxid, it is converted into a white crystalline mass which must not be mistaken for white lead, which is a pure lead car- bonate. These boat-shaped crystals were formerly very evident, even in white lead of commerce, but at the present time white lead is so scientifically manufactured that these boat-shaped crystals are seldom, if ever, seen. One of the defects mentioned by many writers on white lead is its susceptibility to sulphur gases. In nature these sulphur gases are generated in two places; 30 CHEMISTRY AND TECHNOLOGY OF PAINTS namely, in the kitchen of every house, and in and around stables and outhouses. In kitchens the cooking of vegetables liberates hydrogen sulphide to a great extent, the odor of which is familiar to everybody who comes into a house where either cauliflower or cabbage is being cooked. But, inasmuch as undiluted white lead is not often used for interior painting, the defect is not so noticeable. Few stables or outhouses are painted pure white, and when they are painted white the painter generally has sufficient knowledge of the subject to use zinc oxid instead of white lead. It cannot be denied that the ease of applica- tion of white lead, as well as its enormous covering property, has had much to do with the preference for No. 17, LEap CARBONATE CrysTAIs— ft ag q paint. With the ex- page aes 4S ception of lithopone, it has a greater hiding property, volumetrically considered, than any other white paint; on the other hand, gravimetrically considered, it has less body than any of the lighter paints. The addition of an inert filler, such as artificial barium sulphate, silica or barytes, improves white lead con- siderably. These inert fillers, which will be considered under their proper headings, are not affected by chemical influences in the slightest degree, and where they are used in the proper proportions additional wearing quality, or “life,” as the painter calls it, is given to the paint. The percentage of inert fillers which can be added to WHITE PIGMENTS 31 white lead varies up to 50 per cent. More artificial barium sulphate than natural barium sulphate can be added: If a comparative exposure test be made, both on wood and metal, of undiluted white lead and white lead containing an inert extender, it will be found that at the end of eighteen months the paint which contained the filler is in a better state of preservation than that which did not contain it. Generally considered, white lead is an excellent paint, more particularly when added to other materials. SULPHATE OF LEAD Formula, PbSO,; Specific Gravity, 6.2 to 6.38 It must be borne in mind that the sulphate of lead of commerce, which is not so frequently met with nowa- days as formerly, is a very poor paint material, and it must not by any means be confounded with sublimed white lead, which is at times erroneously called lead sulphate. The lead sulphate of the paint trade is a nondescript article which was sold as a by-product by the textile printers who used acetate of lead as a mordant. Sul- phuric acid was added to this liquid and the precipitate was. sold to the paint trade under the name of lead bottoms or bottom salts. Occasionally this material is still met with, and wherever it is used in a mixed paint it does more harm than good. It is likely that the pure neutral lead sulphate, which is a good oxidizing agent and which dries well, and covers fairly well, could be used for ordi- nary light tints if diluted with the proper inert materials, but the lead sulphate which is sold by the textile printers is always acid and is sometimes coarse and crystalline, though at other times quite fine. The chemist, the paint 32 CHEMISTRY AND TECHNOLOGY OF PAINTS maker and the engineer must never confound this lead sulphate with the lead sulphate contained in sublimed lead, zinc lead or leaded zincs. SUBLIMED WHITE LEAD Specific Gravity, 6.2 Sublimed white lead is an amorphous white pigment possessing excellent covering and hiding power, and is very uniform and fine in grain. It is a direct furnace- product obtained by the sublimation of Galena, and within the last ten years it has come into great prom- inence among paint makers, now being regarded as a stable, uniform, and very valuable paint pigment. The author has examined a great many paints containing sublimed lead. Among one hundred reputable paint manufacturers in the United States sixty-five used sub- limed lead. About eight thousand tons were used in the United States in 1905. Considering the face ana: sublimed lead as a pigment is about twenty-five years old, it is very likely, judging from its qualities, that it will be used more universally and in larger quantities in the future. When mixed with other pigments, such as zinc oxid, or carbonate of lead, and the proper reducing materials added, such as silica, clay, barium sulphate etc., it pro- duces a most excellent paint and at the seashore its wearing quality is superior to that of carbonate of lead. In composition it is fairly uniform. From the analyses of thirty-four samples of sublimed lead its composition may be quoted as 75 per cent lead sulphate, 20 per cent lead oxid, and 5 per cent zinc oxid, although each of these figures will vary slightly either way. Corroded white lead also varies in its percentage of hydroxid, but WHITE PIGMENTS =e for analytical purposes a constant must be admitted which will fairly represent the composition. The question has arisen of late years whether sublimed lead is a mixture of the three components just cited, or whether it is a combination of lead sulphate and lead oxid with the mechanical addition of zinc oxid. Inas- much as all the lead oxids that are known in commerce or in chemistry are yellow, red, or brown it is held by many that the lead oxid of sublimed lead is really an oxysulphate, or, in other words, a basic sul- phate of lead. A mixture of precipitated lead sul- phate, litharge, and zinc white in approximately the proportions found in sub- limed lead, when ground in oil and reduced to the proper consistency, dries totally different from sub- No. 18. SUBLIMED LEAD X500. limed white lead; in fact, sublimed lead when ground in raw linseed oil takes two days to dry dust free, but the mixture just cited will dry sufficiently hard for repaint- ing in twelve hours, because lead sulphate is a fair drier and lead oxid a powerful one. Yet the oxysulphate, hav- ing the same composition, behaves totally different from the mixture and in addition is of a different color. Under the microscope sublimed lead shows an absence of crystals and remarkable uniformity of grain. Being a much more inert chemical body than the other lead pigments, it does not react on linseed oil and _there- fore makes a much more durable paint compound. It 34 CHEMISTRY AND TECHNOLOGY OF PAINTS has been urged that sublimed lead is not as susceptible to sulphur gases as white lead, but this the author has not been able fo substantiate, for while it may take hydrogen sulphide a longer time to discolor it, it is simply a question of degree and it is acted upon by sul- phur gases, although not as quickly as white lead. Sublimed lead can be determined in a white mixed paint without any difficulty, owing to the established ratio between lead oxid and lead sulphate. The per- centage of free zinc sulphate in sublimed white lead varies from a trace to a’half per cent, and many times a chemist will report more zinc sulphate than is actually present, because in washing or boiling a dry or extracted sample the lead sulphate may interact with the zinc oxid and show a larger percentage of zinc sulphate than is really present in the dry products before analysis. Sublimed white lead as a marine or ship paint is of much value, owing to its hardness of drying and imper- viousness of film. OZARK WHITE Ozark White is a very desirable pigment and has all of the good qualities of Standard Zinc Lead White and Sublimed White Lead. It is very largely used in the manufacture of mixed paint. In many respects it is superior to the old Standard Zinc Lead White, because its approximate composition is 60 per cent of zinc oxid and 40 per cent of lead sulphate. The process is so highly perfected that the manu- facturers can control the composition so as to insure a variation of not over 2 per cent, and with rare exceptions the material does not vary 1 per cent from the composition given. To attain this degree of uniformity, a complete analysis of every car of ore is made as soon as it is received WHITE PIGMENTS 35 before passing it to the mechanical mixers. At the mixers another analysis is made, and an ore higher in zinc or lead added, as the case may require, in order to have the proper metal constituents. The ore, after being mixed with the proper proportion of coal and antifluxing material (crushed silicious rock or mine screenings), is charged into furnaces which have previously been bedded with a sufficient amount of coal to start combustion. The furnaces are then sealed, allowing the temperature to rise to about 2300 F., at which point it is held until the zinc and lead pass off together in the form of fume, which is conducted by means of suction fans ee through pipe-lines for a distance of about 500 feet, where it enters large brick bag houses. The fumes have by this time lost con- siderable of the heat, so that they may be gathered into fabric bags, where the gases pass out and the pigment is collected. From the bag house the pigment is conveyed to an automatic packer and placed in barrels of suitable weight, and is then ready for the consumer. An actual chemical analysis of an average type of Ozark White shows the following: No. 19. Ozark WuitE—Photomicro- graph 300. - Piet Pah he es, a fea ng BS 50182 pet oa Pi S Glo > a ESI aie ena ee ar pegs 26.05 MN Rg St) fn ted Oo ae TSlolsn © coll ARG snk i Rei aN alee Gion yr aeage Me ee sc a patois Pee er ak Sour stat RP aes I len ie nash Oe ek a oe ae ake Total 99.98 per cent 36 CHEMISTRY AND TECHNOLOGY OF PAINTS ZINC OXID Formula, ZnO; Specific Gravity, 5.2 Zinc oxid as a paint pigment is only sixty years old, and when it is taken into consideration that in that short space of time its use has grown until in 1905 nearly seventy thousand tons were used in the paint industry in the United States, it speaks for itself that the material must be of exceptional merit to have advanced so rapidly. At the same time, although it is impossible to obtain any exact figures on the subject, it is probable that more than one half of these seventy thousand tons was used in con- nection with other materials. The discovery of zinc oxid by Le Clair in France and Samuel T. Jones in America is sufficiently well known, and has been quite thoroughly written up in other books. The former made zinc oxid by subliming the metal; the latter made it by subliming Zincite and Franklinite ores. The specific gravity of zinc oxid will average 5.2, and fifty pounds will take fifty pounds of linseed oil; in other words, to produce the proper mixed paint it will require a far greater proportion of linseed oil than white lead will take. It is generally stated in text-books that zinc oxid is not affected by sulphur gases and _ therefore will not turn color. This statement is not exactly correct; the author always contended that zinc oxid is not visibly affected by sulphur gases, but there is no doubt, as any chemist will admit, that zinc oxid is affected by sulphur gases, although not to~the same extent as white lead. As zinc sulphide, zinc sulphite, and zinc sulphate are white products, the adsorption is not evident to the eye, and hence the erroneous statement has crept into use that zinc oxid is not affected by sulphur gases. WHITE PIGMENTS 37 When mixed with linseed oil and the proper amount of drier, it sets and dries much more slowly than white lead. Nevertheless this drying continues in the form of progressive oxidation until the surface becomes very hard. A comparison between zinc-oxid and white-lead paints will show that the progressive oxidation which takes place when white lead dries produces a chalky mixture, while the reverse is true of zinc oxid, which will produce a hard and brittle vitreous surface which is somewhat affected by temperature changes. Owing, therefore, to the diverse effects of the two pigments, a combination of lead and zinc is often well recommended. The hard drying of zinc has not, however, been very well understood. Fifteen years ago the author undertook a series of experi- ments and found that the drier was very largely respon- sible for the hardening action of zinc. If the linseed oil be prepared with litharge (PbO), the resulting zinc paint will last far longer and be much more flexible and consequently not readily cracked when exposed to a variation of temperature of even 130° F., such as we have in this climate. If, however, a drier is used in which manganese (MnO.) and red lead (Pb;O,) have been cooked with the oil, the action of the manganese continues until a vitreous surface is the result. It is owing to the result of these investigations that the use of American zinc oxid made from Franklinite ore has become so general for the manufacture of white table oilcloths. (See Journal of Society of Chemical Industry, No. 2, Vol. XXI, Jan. 31, 1902.) When enamel paints are made of an oil varnish and zinc oxid, and the drier in the varnish is composed of manganese and lead, the enamels eventually become hard, evidently through the catalytic action of the man- ganese. It is desirable to omit the manganese in high 38 CHEMISTRY AND TECHNOLOGY OF PAINTS grade enamels, or, where manganese must be used in order to obtain a rapid setting, the borate of manganese should be employed, but only in very small quantities. The American zincs are: First. The Florence Red and Green Seal zincs, which are made by the sublimation of the metal and are prac- tically pure and equal in all respects to those made in France and Belgium. Second. Tne New Jersey zinc _ oxids, which are made from Franklinite ore and are free from lead and frequently run over 99 per cent ZnO. Third. Mineral Point zinc, which is made at Mineral Point, Wisconsin, and contains from. 2 to 4 per cent of lead No. 20. AMERICAN WHITE SEAL ZINC OXxIDE— Photomicrograph x510 98.5 ZnO made direct sulphate. from the ore. Very fine material of uniform Fourth. The grain. Dry specimen. leaded zincs made in Missouri, which contain from 4 to to per cent of sulphate of lead. - Zine oxid chalks to some extent in the same manner as white lead, but only if the atmosphere is charged with carbon dioxid or salt. The same experiment which was carried out with white lead in order to show its solubility in a solution of carbon dioxid was carried out with zinc oxid and the same result obtained. Much weight cannot be given to these experiments, because these chemicals are not always present in the atmosphere. They are WHITE PIGMENTS 39 merely chemical results which demonstrate both the cause and effect, but it is of some interest to know why the paint films perish. The zinc oxids made from western ores are slightly more permanent than those made from the New Jersey ores, and as paint materials they possess the advantage of containing a larger quantity of lead sulphate. | Nearly all zincs contain a small percentage of zinc sulphate. Much unnecessary trouble has been caused by the criticism against zinc sulphate. Where a paint contains moisture or where water is added in a very small amount to a heavy paint in order to prevent it from settling, and not more than one per cent of actual water is contained in the paint, zinc sulphate formes an excellent drier, particularly where it is de- sirable to make shades which contain lampblack. The outcry against zinc sul- : : phate is unwarranted, No. 21. American Wuire Seat Zinc because as much as 5 per OxIDE X510. Ground in oil. cent is used in making a patent drier. The amount of zinc sulphate, however, in most of the dry zinc pigments probably decreases with age. Zinc oxid or other zinc paint which will assay 1 per cent of zinc sul- phate will, when kept in storage for six months, show a decrease in the zinc sulphate to one half of 1 per cent. In the enamel paints the presence of zinc sulphate is not a detriment, and in floor paints it might be considered 40 CHEMISTRY AND TECHNOLOGY OF PAINTS as a slight advantage, for it aids in the drying and harden- ing. However, too much of any soluble salt 1s never to be recommended. ZINOX This is a hydrated oxid of zinc not manufactured in this country, but made and used almost entirely in France. It is not yet sold dry, but generally sold either in the form of a ready mixed enamel or in a semi-paste form, and is presumed to possess advantages over zinc oxid. From experiments which the author made it has been found that the hiding power and working quality are practically the same as that of zinc oxid. It pos- sesses, therefore, no marked advantage over a zinc oxid enamel, although it is stated that it remains in sus- pension longer than any other pigment. The zinc oxid enamels all remain in suspension a very long time, and even though they settle they do not settle very hard and can be very easily stirred. In thinner media, such as are used for the manufacture of flat wall paints, the hydroxid of zinc has some advantage over the oxid, as it produces a paint that remains in suspension longer and is more ready for use than that made from the oxid. LITHOPONE Synonym: Oleum White, Beckton White, Charlton White, Ponolith, Jersey Lily White, Orr’s White, Albalith, etc., etc. Chemical Formula, ZnS + BaSO,; Specific Gravity, 4.2 When solutions of zinc sulphate and barium sulphide are mixed together in molecular proportions a heavy flocculent precipitate is formed according to the following reaction: ZnSO, + Aq + BaS + Aq = ZnS + BaSO, + HO. The theoretical percentage will be about 29.5 per cent zinc sulphide and 70.5 per cent barium sulphate. This WHITE PIGMENTS AI precipitate as such has no body or covering power, and when washed and dried is totally unfit for paint pur- poses; but John B. Orr, of England, in 1880 discovered that when it is heated to dull redness, suddenly plunged into water, ground in its pulp state, thoroughly washed and dried, its characteristics are totally changed, and it -makes a very effective and durable pigment for paint purposes. In the first place, it is then a brilliant white; in the second place, it is extremely fine in texture; and in the third place, it has more hiding power than pure zinc oxid. Owing to its chemical composition it is stable in every medium known for paint purposes, excepting those which are highly acid. It took several years to perfect the manufacture of lthopone, but it may be easily said that at the present time lithopone is made with great uniformity and has valuable properties, as will hereinafter be shown. The method of manufacture is quite simple, success depending very largely on the purity of certain materials. It is worthy of mention, however, that the average chem- ist unfamiliar with both the theory and practice of its manufacture cannot make it successfully. In the first place, solutions of barium sulphide and zinc sulphate of known composition must be made. The fact that they are impure has no effect on the ultimate product, provided the chemist knows the impurities he has to deal with and the simple methods for their elimination. For instance, the zinc sulphate must be free from iron, or a yellowish product is the result. The solutions must be standardized for each batch. The impurities can be eliminated during the process of manufacture, or, more properly speaking, before they are pumped into the pre- cipitation tub. The barium sulphide, however, is quite pure, for the 42 CHEMISTRY AND TECHNOLOGY OF PAIN ys reason that metals like copper, iron, and manganese which are likely to be present, form insoluble sulphides. Barium sulphide is made by heating barytes (BaSO,) to dull redness with coal, petroleum residuum, pitch, saw- dust, or other materials having a high percentage of carbon. The resulting reaction may be represented by the following equation: BaSO, + 4C = BaS + 4CO, al- though under many circumstances the reaction is more slightly complicated. After the reaction is completed and before the air can have any influence on the sulphide, the mass is digested in vats and filtered; when the solution reaches a density of 17° Baumé, long, yellowish, needle- shaped crystals separate from the mother liquor. These crystals are almost chemically pure barium sulphide. Re adh With the proper con- centration of the solu- tions, proper tempera- ture and speed at which the two solutions are poured together, the re- sulting precipitate will be of such physical charac- teristics that it can be most easily filtered and dried. It is then placed No. 22. LirHopone (dry) —Photomi- in muffles and _ heated crograph X250, exceedingly fine and above 920° Fahrenheit, uniform in grain. suddenly plunged into water, again ground, washed, and dried. It is then ready for the market. Overheating of the precipitate decom- poses some of the zinc sulphide and converts it into zinc oxid. All of the earlier manufacturers overheated their product, and that is the reason why lithopone formerly contained from 5 to to per cent zinc oxid, whereas theo- WHITE PIGMENTS 43 retically it should have contained none. The manu- facturers of the present day, however, have overcome all these difficulties, so that a remarkably uniform product is obtained, the percentage of zinc oxid being small indeed. We have here an excellent example, as has been stated under another chapter, of a pigment containing 70 per cent barium sulphate, which may be regarded as perfectly pure and normal, and yet twenty-five years ago any pig- ment containing far less barium sulphate than lithopone would have been re- garded as adulter- ated. No man can reasonably state that barium - sul- phate is an adulter- ant to lithopone, for the obvious reason that it is a constituent part of the pigment. IGP Tee te ie ae - Lithopone has No. 23. LitHoPpoNE — Ground in Oil x510. gone through many vicissitudes; no pigment has been blackguarded quite as much as this, and yet no pigment has survived its condemnation as well as this. Almost every paint manufacturer in the United States finds some excellent use for it. Within the last seven or eight years lithopone has come into its own, and today there is no paint manufacturer in the United States, to the best of the author’s knowledge, who does not use this material. Ten years ago very few paint manufacturers used it at all. Since 1906 many chemists, including such capable men as Professor Ostwald, have attempted to find the 44 CHEMISTRY AND TECHNOLOGY OF PAINTS cause of the darkening of lithopone in sunlight. When night comes a change takes place, and the following morning lithopone is as white as it ever was. ‘This property is called the “photogenic” quality. This photo- genic action goes on continually, and there have been a large number of investigators who have attempted to overcome this, and a review of the literature shows that most of the methods, with two or three exceptions, have been empirical. It has remained, however, for Professor W. D. Bancroft of Cornell University to delegate one of his students, W. J. O’Brien, to make these investigations, and the full account is recorded in Volume XIX of the Journal of Physical Chemistry, 113-44 (1915); an extract is herewith given of the phenomenon. That the darkening in sunlight is due to the formation of zinc from zinc sulphide was shown by the fact that the dark product reduced ferric alum, as shown by the appearance of a blue color with potassium ferricyanide, and that it is readily soluble in acetic acid, in alkalies, and in solutions of sodium chloride and sodium sulphate. The zinc is a direct product of the action of light on zinc sulphide. The results of the investigation are summarized as follows: Quenching in water prevents further oxidation of the red-hot zinc sulphide. It also disintegrates the semi-fused mass and dissolves out most of the soluble salts. Heating the barium sulphate-zinc sulphide pre- cipitate is necessary to dehydrate the zinc sulphide and to change its physical condition, so that it forms a dense mass with good body which can be ground more readily. The yellow color produced on overheating is due to an oxid film, as was shown by Farnau. The darkening of lithopone is not due to impurities such as iron, lead, cadmium, etc. The presence of salts which form soluble zinc salts, such as sodium chloride, sodium sulphate, etc., WHITE PIGMENTS 45 accelerates the darkening of the lithopone. These salts dissolve away the zinc oxid film. This is similar to the behavior of magnesium in water. Magnesium does not decompose water very readily at ordinary temperatures. In the presence of magnesium chloride, however, the action takes place vigorously. The presence of salts which form insoluble zinc salts, such as the alkaline phosphates, bicarbonates, ferrocyanides, and borates, retards or pre- vents the darkening of lithopone. The action of light on the zinc sulphide is a reducing one, hydrogen sulphide and metallic zinc being formed. The reaction is not a reversible one; the metallic zinc formed is oxidized to zinc oxid; barium sulphate is not necessary for the darkening of the zinc sulphide. Heating the zinc sulphide is not necessary to get it to darken, although heating makes the zinc sulphide more sensitive to light, probably because the reducing atmosphere and the sodium chloride used remove the zinc film more readily. The zinc oxid film can be removed by boiling in a concentrated solution of zinc chloride. The zinc sulphide so treated will darken in the presence of a reducing agent. When barium sul- phate is precipitated with the zinc sulphide, it aids the darkening, due to the fact that it adsorbs the zinc sulphide, thereby giving increased surface exposure of the zinc sulphide. It probably also adsorbs the metallic zinc. The zinc sulphide will darken without the presence of a reducing agent if it is precipitated with barium sulphide and boiled in a concentrated solution of zinc chloride. The barium sulphate probably adsorbs metallic zinc as well as zinc sulphide, thus making the latter sensitive to light. The patented processes for the prevention of the darkening of lithopone depend upon the formation of an insoluble film around the zinc sulphide. It is impossible to make a lithopone that will not darken unless there is a film 46 CHEMISTRY AND TECHNOLOGY, OF PATA protection of some kind over the zinc sulphide. A litho- pone of good quality that would not darken was made by producing an oxid film on the zinc sulphide and keeping the oxid content above 3 per cent and below 5 per cent. Aluminium oxid can be substituted for the zinc oxid. A film of sulphur protects to some extent; no experiments were made to determine the maximum efficiency possible. From the above we can readily see that the theory is a tenable one, and that the action of light on zinc sulphide is a reducing one, sulphuretted hydrogen and metallic zinc being formed. Metallic zinc is again converted into zinc oxid, and the color of the metallic zinc mixed with the other bases gives the gray shade that is apparent. The manufacture of a lithopone, therefore, that would not darken, by producing an oxid film and keeping the oxid content above 3 and below 5 per cent, would have its disadvantages, for in a rosin varnish or an acid resin varnish livering would eventually take place, and one of the principal features of lithopone has been that an acid resin or rosin varnish could be used and no chemical re- action would take place. The large use of lithopone today is for flat wall paints, for it can be mixed with the China wood oil-rosin var- nishes without the danger of livering or hardening, and it has every advantage as far as hiding power and freedom from mechanical defects that white lead and zinc oxid have, with the added advantage of being non-poisonous (although the danger of using a poisonous material on a wall is largely overestimated). Lithopone is likewise very largely used in the cheaper grades of enamel paints. As an interior white, a first coat white, or as a pigment in the lighter shades for floor paints, lithopone cannot be excelled for its body, durability, hardness, fineness of grain, and ease of application. It does not oxidize pro- WHITE PIGMENTS 47 gressively, and this single feature has made it invaluable to the table oilcloth and floor oilcloth industry throughout the world. Its indiscriminate use, however, is not to be recommended, and the paint chemist should be permitted to decide when its value is the greatest. As a marine interior paint, either as a first coat or for making neutral paints where other whites would be necessary, it is found to outlast both zinc oxid and lead carbonate. Since the foregoing chapters were written, nearly ten years ago, there has been a very great improvement in the manufacture of lithopone, and nearly all the manufacturers today are making lithopone which is absolutely light-proof and some are making lithopone which contains as little as 4 of 1 per cent of zinc oxid or zinc hydroxid. Zinc oxid finds its way into lithopone when the barium sulphate is overreduced to barium oxide, or air comes in contact with the reducing mass either during or just before the final reduction. This is most evident when an analysis of barium sulphide is made, and the barium and the sulphur do not check together, the barium being slightly higher than the theoretical amount necessary for combination. This indicates that barium oxid is present in the barium sulphide. The manufacture of light-proof lithopone is by no means simple, because it depends more than anything else upon the purity of materials, particularly that of the zinc sulphate. The testing of lithopone for its light-proof quality can best be done by means of the ultra-violet light, and where a Wood screen is inserted, the non-lightproof lithopone in its dry state will fluoresce brilliantly. It is sometimes possible to determine the origin of the sample depending 48 CHEMISTRY "AND “TECHNOLOGY OF FAinae upon the color of the fluorescence. Even in comparatively stable lithopone any particles of zinc oxid or zinc hydroxid will show up as brilliant white specks. Lithopone should also be tested for its light-proof qualities in dry state or in oil, and always in a watch glass in which the lithopone has been moistened with water. Blackening or darkening will sometimes begin in a few seconds, and if the lithopone is really light-proof. a five minute test is ample. TITANIUM WHITE Formula 25%. TiOs + 75% BaSO, Syn: elitanox The value of titanium dioxid as a pigment of great opacity and chemical stability has long been known, but its industrial production on a large scale, and its exploita- tion as a paint pigment were not placed on a successful basis until t919, when companies in Norway and the United States put it on the market in regular production after years of research. Titanium occurs abundantly in many parts of the world, in such ores as rutile, anatase, and brookite, and it forms the chief constituent of ilmenite which has been variously described as a combination with oxid of iron with the formula Fe(Mg)TiO; + 10 Fe.O3; and as a ferrous titanate with little or no actual Fe,O;. The present method of production consists of first freeing the crude ore, prin- cipally ilmenite, from as much of its impurities as is possible by mechanical means, pulverizing it, and mixing with con- centrated sulphuric acid to a thick paste. On heating this, a violent exothermic reaction takes place, and the resulting mass which contains sulphate of iron and titanium is ex- tracted with water. When the solution is heated nearly to boiling, the titanium sulphate, an unstable compound is WHITE PIGMENTS 49 hydrolized to insoluble basic titanium sulphate which pre- cipitates in a very finely divided form. This precipitate is then washed by decantation, and in the form of a pulp, roasted in a rotary kiln where it becomes titanium oxid. Precautions must be taken throughout the process to keep the material in the proper physical condition so that it may be finally ground into a product having the best pigment properties. It has been found that a mixture of 25 per cent titanium dioxid and 75 per cent precipitated barium sulphate gives the best results as an all-around pigment. The barium sul- phate is added by suspend- ing it in the solution from which the basic titanium sulphate is precipitated and it is an integral part of the pigment. It is by no means an adulterant. Some processes call for the precipitation of BaSQ, on the TiQ, as it is made, the disadvantage in this case being the large iron contamination in the resulting precipitate. One of the principal obstacles the manufacturers had to contend with during the development of titanium white, was the yellowish cast of their final product, which, at the time, was generally considered as being due to the small amount of iron remaining as an impurity. It was eventually concluded, however, by some manufacturers, that this con- dition was caused by molecular change during the calcina- tion, for by excessive calcination, yellowish crystals of rutile could be produced. After an enormous amount of No. 24. TITANOX X700. 50 CHEMISTRY AND TECHNOLOGY (OF - PATA ES research, it was found, that if a small proportion of the titanium was present in the form of phosphate, this change did not take place. Titanium white as produced at present is a pure white pigment having great hiding power or opacity, and is prac- tically inert to the usual paint and varnish vehicles. It may be used in varnishes that would react with zinc oxid, and it has a high resistance to acid and alkaline fumes. The judicious mixing of this material with zinc or lead produces satisfactory paints. It has been found that when used alone, the paint films are generally too soft, but when 20 to 30 per cent zinc oxid is added, a white paint of exceptional durability is obtained. For tinted paints, 40 to 50 per cent of zinc oxid is recom- mended. ‘Titanium white is made under the trade name Oleaelitanex,. ; As a pigment for exterior purposes it cannot compare with lead or zinc as it chalks very badly, and even chalks to a considerable extent when blended with zinc, lead, Blanc Fixe or other pigments. For making enamels for interior use it has excellent qualities, and is greatly im- proved when ground with about ro per cent of Asbestine. It is very likely that Titanox will be continually im- proved so that eventually formulas will be devised whereby it will find considerable advantage as an exterior paint. ANTIMONY OXID Trade name ‘‘Timonox” The development of this material as a paint pigment has been similar to that of titanium oxid. It is produced commercially in England under the trade name of Timonox by the roasting of metallic antimony and its sulphide ores. Two grades are on the market, the “Red Star” being the WHITE PIGMENTS 51 -whiter and the “Green Star’’ being finer in texture, but of a pale ivory tint. Its physical properties are similar to those of titanium oxid and similar claims are made for it. No. 25. WHITE ANTIMONY OXID X315. Timonox is supposed to be immune to sulphur fumes, but this is not correct as it turns reddish-yellow (sometimes brownish-yellow if it contains a trace of iron) when sub- jected to sulphur gases. CHAPTER Ti THE OxIps OF LEAD THE oxids of lead used in making mixed paints are principally litharge, which is PbO, and red lead or orange mineral, Pb;QOu,. LITHARGE Chemical Formula, PbO; Specific Gravity, 9.2 to 9.5 Litharge is the first oxid of lead; that is to say, when lead is melted and heated in a current of air the first oxid produced is the PbO, yellow in color, and known as litharge. Very pure litharge has the color of pale ochre. Litharge in the manufacture of preservative paints has excellent protective qualities, because it is basic and resists corrosion. Furthermore, litharge and linseed cil make a very hard cementitious film which withstands abrasion, but unfortunately litharge combines with lin- seed oil so rapidly that when used in mixed paints to any great extent it tends to “liver” and saponify. On - the other hand, a number of black paints which are composed of lampblack, carbon black, charcoal, or a mix- ture of these, are held together by the use of litharge, and where these paints are used within a month or two after they are made they serve their purpose perfectly. Litharge is soluble in acetic acid, and the other impurities in it are generally insoluble, so that a very rapid test can be made from the paint manufacturer’s point of view by simply boiling in acetic acid. Litharge varies in texture under the microscope, as is shown in the accompanying photomicrographs. 52 THE OXIDS OF LEAD 53 Flake litharge is generally used by varnish makers or oil boilers for making drying oil, but the more finely powdered forms of litharge have a peculiar construction, and when the litharge is impure and contains metallic lead and red lead it is distinctly noticeable under the microscope. Rep LEAD Chemical Formula, Pb;0,; Specific Gravity, 9.0 Red lead is a very heavy orange-red pigment, more or less crystalline in structure. It is prepared by heating litharge to a temperature of 600° to 700° F. Owing to the conditions under which it is made it contains from a trace to an appreciable percentage of litharge (PbO), and when used for paint pur- poses it cannot be said that-a small content of litharge does any harm. When prepared in linseed oil it must be freshly used, No. 26. RED Lrap—Photomicrograph otherwise NM forms ae dis- X00. tinct combination with lin- seed oil and becomes hard and unfit for use. In its physical characteristics it can be compared with plaster of paris. It acts very much like plaster of paris when mixed with water. Once set, it may be reground and will never set again. Its use as a priming coat for structural steel has been enormous, but engineers who have studied the subject have come to the conclusion that there are other materials just as good, or better, which are easier to apply and do not possess the characteristic difficulties 54 CHEMISTRY AND TECHNOLOGY OF PAIN aS of application. The author has made many investigatioris on this subject, and for further detail would refer the reader to the Journal of the Society of Chemical Industry, Vol. XXI, January, 1902, and Vol. XXIV, May, 1905. There are some manufacturers in the United States. who make red lead from litharge and use nitrite of soda as an oxidizing material, and in the manufacture of this type of red lead carelessness in manufacture will result in a fairly large percentage of caustic soda remaining in the red lead. Caustic soda finds its way frequently into litharge when it is made by what is known as the nitrate process, in which nitrate of soda and me- tallic lead are fused to- gether, yielding an oxid of lead; PbO} andeniitiice on soda, NaNO,.! Red lead manufactured by this pro- cess will usually contain a small amount of caustic soda and nitrite of soda, ANG seSuCchoered — 1eAc. eecls though otherwise pure, makes a very poor paint, because the caustic soda saponifies the linseed oil, and exposure to weather of a few months will turn the red lead white or pinkish white and make it very soluble in rain water. Rust is also rapidly produced under such red lead, and therefore in specifying red lead it is well for the engi- neer to insert a clause that an aqueous mixture of red lead shall show no reaction with phenolphthalein. Within the last five years a great improvement has been made in the manufacture of red lead, and this No. 27. LIrHARGE—Photomicrograph X<300. 1 See Holly’s “Analysis of Paint and Varnish,” p. 221. THE OXIDS OF LEAD 55 improved form has been known as Dutch Boy Red Lead, which is practically a chemically pure Pb;O,. Pure red lead was the one material which had never been sold either ground in oil or ready for use, owing to the fact that the large content of litharge combined with the fatty acid of the oil and the glycerine and formed a lead soap. It is well known that litharge cement, used for many pur- poses around a factory, is litharge and glycerine, which sets up hard within an hour and forms a vitreous product. It is also well known that when linseed oil is neutralized with caustic soda, and the resulting linoleate of soda soap filtered out, a ready mixed or semi-paste red lead can be made which will remain soft for many months, but the proprietary brand of red lead just referred to manufactured by the National Lead Company, is a pure red lead similar in composition to orange mineral, which remains soft and produces a paint that has many advan- tages over the old-fashioned red lead. Many engineers and shipbuilders prefer to use dry red lead, and a proper specification for dry red lead should be one that will contain the minimum amount of litharge. : It cannot be denied that red lead is one of the best priming materials that we have, but under no circum- stances should less than 28 lbs. of dry red lead be mixed with one gallon of linseed oil. Many of the bad effects and failures of red lead are not due to the lead itself, but to bad application and insufficient dry materials. As a matter of fact, the best results with red lead are obtained (in the author’s experience) by using 33 lbs. and one gallon of linseed oil. To this oil may be added one half pint of any good Japan drier. As a priming coat red lead possesses excellent pre- servative qualities, providing it be properly applied within 56 CHEMISTRY AND TECHNOLOGY OF PAINTS a reasonable time. If red lead be used in the proportion of 17 lbs. to one gallon of linseed oil it forms a very poor coating on account of the separation of the pigment from the cil, particularly on a vertical surface. In a pamphlet published by a manufacturer a large number of precautions were given to the consumer for the prepara- tion of red lead as a priming coat, the neglect of any one of which might produce failure for the paint. As a prominent engineer remarked, he did not care to specify a paint in which there were seventeen chances of its failure due to a’ possible fallibility of hu- man nature. The use of a dry pigment mixed with oil and applied within one hour of its mixture is con- trary to the progress of the present day, when paints finely ground by machinery eee taking the No. 28. FRENCH ORANGE MINERAL — place of all others. A dry Photomicrograph X250, not very uni- pigment stirred by hand ‘0m ™ stn. in a pail of oil carries with it a large number of air bubbles which become encysted and carry oxygen and other gases to the surface to be protected. The engineer should, therefore, not specify that a paint be made entirely of red lead and linseed oil and sent ready for use to the place of application when such specifica- tions cannot be reasonably executed. On the other hand, where red lead is specified the engineer or paint manufacturer who can supply a material containing between 4o and 50 per cent red lead and 50 and 60 per cent inert base is delivering a far better article, THE OXI DSO LEAD 57 which can be more easily applied than the undiluted red lead alone. The author made a large number of experiments on red lead mixed with linseed oil containing a small per- centage of drier, applying these mixtures to steel. The mixture was first applied the moment it was thinned, and then at short intervals, up to the moment the red lead began to combine with linseed cil so as to make it impossible to handle the brush. The results of the experi- ment showed that freshly applied red lead was not as good as it was if applied one hour after it was mixed. The paint with which these experiments were made con- tained 24 lbs. red lead to one gallon of paint, which is approximately equal to 33 Ibse, ary. red. leat. to,,one gallon of oil. The difficulty No. 29. RED LrAp — Photomicrograph in handling paint of this x200 of paint film freshly applied, kind is very pred t owing showing separation of the pigment to the excessive weight of from the oil. ; ‘ ; the paint as carried by the brush. Structural iron painters all complain that muscular fatigue ensues where undiluted red lead is used, and when the inspector is not watching they will surreptitiously add an excessive quantity of oil, or volatile thinner, in order to lighten their labor, and for this reason red lead has frequently failed, when as a matter of fact it would have proved a perfect success had the original specifications been adhered to. On the other hand, there should be no need of using a protective paint involving such great difficulties when there are dozens of others 58 CHEMISTRY AND TECHNOLOGY OF PAINTS that are as good, not only from the standpoint of pro- tective influence but also on account of the ease of mechanical application. It has been mentioned by many writers that one of the serious defects of red lead is the ease with which it is attacked by sulphur gases, but this objection does not hold good where it is properly and quickly coated over with a protective coat of the bituminous class. That red lead in its pure or concentrated state is not as good as a paint containing a solid diluent has been shown time and again where silica, lampblack, graphite, silicate of alumina, and such lighter pigments were mixed with it. Its extraordinarily high specific gravity is very much against its use as a paint, but if a mixture of one pound red lead and one pound wood black is taken No. 30. Rep LEAD — Photomicrograph the average specific gravity 150, applied one hour after mixing, of the two is equal to that showing separation and air bells en- ‘ q 2 cysted in film. of zinc oxid. Its spreading and lasting power is increased, so that a mixture of this kind is equal to a mixture of any of the good pre- pared paints for structural steel. Two large exposure tests made by the author in 1899 and examined in 1905 showed that a mixture of 50 per cent red lead and 50 per cent graphite ground fine and mixed in a pure Imseed oil containing 5 per cent of lead drier wore almost as well as a mixture of 75 per cent Fe,O; (ferric oxid), 20 per cent silica, and 5 per cent calcium carbonate. The former paint, when the hand was rubbed over it, THE OXIDS OF LEAD 59 showed slightly more destruction of the oil, the graphite giving a stove polish effect on the hand. The latter paint also showed a very slight stain on the hand, but not quite as marked as the former. The metal underneath both was in a good state of preservation, three coats of paint having been applied. The exposure was made on a slanting roof in New York City. Red lead has had the great advantage of having been the first protective paint ever used, for years no better paint being known. In this respect it is analogous to white lead. Much of the good reputation of white lead is due to the fact that for centuries there was no other white paint, consequently no comparison could be made. It must be borne in mind that all these experimental researches concerning red lead are based on very fine red lead, and no consideration is given to the detrimental reports concerning red lead due to the fact that it was improperly made and coarse. : A laboratory test of red lead always shows up remark- ably well. A steel saucer painted with red lead in the laboratory will demonstrate that this pigment is superior to many others, but a field test of material made accord- ing to a laboratory formula and applied on several tons of steel will generally show the opposite, for the obvious reason that in the laboratory a small test is usually carefully applied and little exertion is necessary, either with the mixing of material or for its application. The temperature conditions of the laboratory being normal, the person who mixes the paint usually scrutinizes the result carefully. On the other hand, in the field or at the shop a-brush is used which will do the greatest amount of covering with the least amount of exertion. The mixture may not be made by the best possible for- mula, and, if it is, more thinning material is generally 60 CHEMISTRY AND TECHNOLOGY OF PAINTS added until it works freely. The vertical part of the surface will, on account of its position, be more difficult to cover, and the paint will sag or run from it; whereas, the flat plate or saucer-shaped cup used in the laboratory holds the material in place by virtue of its position. At the present time, red lead is totally different as a steel protective paint as compared with the dry red lead of a decade ago. Improvements in its manufacture have led to the perfection of red lead ground in oil, so that it will not thicken or liver. In the United States a red lead has been marketed under the name of “Dutch Boy Red Lead in Oil,” which can be reduced with linseed oil and drier, and is far superior to the old-fashioned dry red lead mixed on the job. It is a most excellent paint, and when coated over with a waterproof paint gives immunity from rust. In the sublimation of Galena a peculiar sulphide of lead is produced, which has been known commercially as blue lead, on account of its blue-gray appearance. This product has been on the market for several years. The contention is that sulphur fumes do not affect it as they affect red lead. As a priming coat it has been well spoken of. Its composition 1s as follows: CatDOlines qten eames B26 a ae ieee Lead Sulphate...... 52°02. 5 7 en 49.79 Lead Sulphite as 20504. che ee 1.44 Lead Sulphtigeaieess Ai RSW. a 4.93 Lead*Oxid hee 29048 i. 6 AI. 34 Zine. Oxid See eee 2945 2k ae T.00 100. Or 100,22 No truly representative analysis of this material can be given, owing to the variation in the amount of sul- phate, sulphite, and sulphide. The material is not very THE OXIDS OF LEAD 61 fine; in fact, it contains an appreciable amount of grit, which, however, is removed in the second grinding. The pigment is not permanent to light, but in all probability this change in its tone is due to a chemical rather than to a physical decomposition. CHAPTER IV THE INORGANIC RED PIGMENTS THE red pigments used in the manufacture of mixed paints are principally the oxids of iron, the red oxids of lead, and the permanent vermilions. No space will be devoted to the sulphide of mercury (quicksilver ver- milions), as the use of these materials has been super- seded entirely by aniline or para-nitraniline vermilion. Likewise no attention will be paid to the sulphide of an- timony reds, as they are obsolete in paint manufacturing. Among all the red pigments in the paint industry the oxids of iron take the lead as by far the most useful. Several years ago the author called attention to the fact that various forms of ferric oxid having the formula Fe,0; could be used as rubber pigments. The sulphur used in the vulcanizing of rubber had no effect on the ferric oxid, no sulphide of iron being formed in the com- bination. On investigation it was found that some forms of ferric oxid are remarkably stable in composition, acting in many regards like a spinel. Exhaustive tests made with some of the ferric oxids used as paints for the pro- tection of steel and iron shcw that they are far superior to red lead and to graphite as paint protectives, being midway between the two in specific gravity. A mixture of graphite and ferric oxid (containing 75 per cent Fe,O; and 25 per cent silica) outlasted graphite by two years and red lead by three years. These tests were made on horizontal roofs, and eliminating the question of the cost 62 THE INORGANIC RED PIGMENTS 63 of the paints, the ferric oxid stood the test and was the cheapest in the end. No argument can be adduced that ferric oxid is a carrier of oxygen, for it is a complete chemical compound, is not readily acted upon by dilute acids, not affected by alkalis nor by sulphur gases, and as a paint the author has not been able to demonstrate that it reacts on linseed oil. All of these arguments refer, of course, to a ferric oxid of known purity and definite composition either as pure Fe.O; or as Fe.O; containing 25 per cent of silica. In the course of its manufacture from the waste products of wire mills, for instance, or direct from ferrous sulphate, the processes being analogous, there is a likelihood that a small percentage of free sulphuric acid may cling mechanically to the substance. A good sample boiled with water and tested with methyl orange will demon- Bitate tnis detect. It is wise, therefore, under all: cir- cumstances to add up to 5 per cent calcium carbonate in any or all of these ferric oxid paints. There is, how- ever, another ferric oxid made from. Persian ore. Over one hundred analyses of this ore in the laboratory of the author have shown that its composition will not vary ‘more than 2 per cent either way, it being 75 per cent _ Fe,O; and 25 per cent SiOx. VENETIAN .REDS Venetian reds have sometimes been described as burnt ochres, but this definition of the Venetian reds is incor- rect. The generally accepted composition of the Venetian red is a combination of ferric oxid and calcium sulphate, in which the ferric oxid will run from 20 to 4o per cent, and the calcium sulphate from 60 to 80 per cent. When ferrous sulphate is heated with lime an interchange or 64 CHEMISTRY AND TECHNOLOGY OF PAINTS reaction takes place, the sulphuric acid of the copperas going to the lime while an oxidation of the iron takes place. Another method known as the wet method is the direct reaction between ferrous sulphate and wet slacked lime. Venetian red has been known as a paint pigment for upwards of a century, and while theory would indicate that it is by no means as desirable a pigment to use as other mixtures of ferric oxid, it must be apparent that : in view of the fact that it Lf. i has given general satisfac- gf | tion it is by no means as — desirable a pigment ae undesira pig as | ‘ ,, , chemists indicate. The ten- & * dency, however, at the ' present time is for manu- : 5 J s / facturers to buy ‘strong Ne So purre._oxids “and™ Yeduce ~~ : : — Co them with other inert ee fillers, for the principal No. 31. ENcLisH VENETIAN Rep— reason that a Venetian red Photomicrograph 250, showing cal- carrying a high percentage cium sulphate crystals. : of calcium sulphate and an unknown quantity of water or moisture tends to become hard in the package, whereas the mixtures of known composition remain soft for many years. Venetian reds are all of the familiar brick color shade, the color of bricks being caused by the same pigment as the one that gives the color to Venetian red. - INDIAN RED This is supposed to have been named by Benjamin West, a-celebrated American artist who lived more than a century ago, and who as a boy used a few primary THE INORGANIC RED PIGMENTS 65 earth colors as pigments for paint. One of these was a natural hematite, and he observed that the Indians used this for painting their faces. The name is also supposed to have had its origin in the fact that “‘Persian’ Gulf Ore,’ which was found in the Orient, was exported to England under the name of ‘‘East Indian Red.” This Persian Gulf Ore is likewise a hematite, and later on a similar ore was found in parts of England which, when mined, looked very much like coal, but when crushed and ground in water turned a deep blood-red. The old name for this mineral is still ‘“‘blood-stone,”’ and some very fine specimens of this mineral are still mined in England in con- junction with beautiful quartz crystals, so that we find in England a care- ful selection. ; The native Indian red No. 32. AMERICAN VENETIAN RED— will run go per cent Fe.Os, Photomicrograph 250, showing fine : grains of calcium sulphate. the American 88 per cent, and the Persian 75 per cent, the balance in every case being silica. The Indian red of commerce, however, is an artificial product made like the base of the Venetian red by calcining copperas and selecting the product as to shade. There is no pigment, with possibly the excep- tion of lithopone and artificial barium sulphate, which will approach Indian red in fineness of grain. The prices which a fine, pure Indian red or ferric oxid of any shade will command are most remarkable, many tons being sold every year in large quantities at as high a price as fifty cents per pound and used entirely for polishing gold, 66 CHEMISTRY AND TECHNOLOGY OF PAINTS silver, and other metals. The well-known “‘ watch-case rouge” is nothing but pure eN Indian red which has been * ground, washed, and treated Bie eee af es mechanically with so much Ligue? ite,, Tee <7 = % care that three- -quarters of ty oe he . / its selling price is represented Wt ee ee ie vy in the labor of manipulation. Ne ge - eS cs a8 pao . ; “et... 8» sii, therefore, fine ferric oxid NRG ae & be mixed with linseed oil it No. 33. AMERICAN HEMATITE — Photo- can be easily seen from the micrograph x250, showing a few large nature of the physical char- reac acteristics of the pigment that a remarkably good result is obtained. CHAPTER V THE YELLOW PIGMENTS THE yellow pigments are the ochres, the raw siennas, chrome yellow, and the chromates. The ochres are all rust-stained clay, and both the French and the American contain approximately 20 per cent of rust or ferric hydroxid and the balance clay. The raw siennas differ from the ochres in that the amount of hydrated oxid of iron is often in excess of that of clay, and the nature of the pigment is such that when finely ground it is a stain and not a paint. The chrome yellows are all lead chromate variously precipitated and of varying composition, depending upon the shade. The other chromates, such as zinc chromate and barium chromate, have come into use in paints within the last ten years, owing to their alleged property of preventing corrosion. AMERICAN YELLOW OCHRE There are large quantities of ochre found in the United States, but principally in Pennsylvania and in Georgia. There are, of course, a great many other deposits, but for the paint industry these are the prin- cipal sources. American ochre ranges in composition from ro to 30 per cent of ferric hydroxid, the balance in either case being clay, and on this point it is well to note that ochre and sienna have the same composition, except- ing that there is generally a reversal in the percentages 67 68 CHEMISTRY AND TECHNOLOGY OF PAINTS of clay and oxid of iron. Some ochres found in America are finer than those imported from France, although French ochres as a general rule are decidedly more brilliant in color. In the trade there are many other ochres, which are sold under the name of cream ochre, gray ochre, white ochre, and golden ochre, all of which are clays containing either carbonaceous matter or iron rust, for, after all, ochre is simply clay stained with rust. Cream ochre contains as low as 5 per cent of iron rust or ferric hydroxid, the balance being silica and clay. It has very little hiding power, and is con- sidered of very little value aS a primer on wood, for No. 34. ORDINARY AMERICAN WASHED which it is used to quite OcHRE — Photomicrograph x250, pow- dered and bolted; lower in iron than a lar Se extent. the French, but of uniform grain. Gray ochre is silica, clay, and carbonaceous coloring matter, or is colored with a trace of ferrous hydroxid or greenish rust. It is used as a filler, or for a cheap paint. White ochre is nothing more or less than clay, and has no value whatever as a paint material. Golden ochre is either French ochre or American ochre which is brightened with some chrome yellow. There are various shades of golden ochre sold, depending upon the shade of chrome yellow with which it is mixed. Some of them are perfectly orange colored, and contain as high as 12 to 15 per cent of chemically pure orange chrome yellow. THE YVELLOW PIGMENTS 69 Green ochre is similar in composition to gray ochre, excepting that it contains a larger percentage of ferrous hydroxid. It is principally found in Bohemia under the name of terre verte. It has little or no hiding power of itself, but is very largely used as a base for cheap lakes on account of its adsorbent quality for cer- tain aniline colors. Yellow oxid is a syn- onym for raw sienna, and is practically the same thing. A typical analysis of yellow oxid will show hydrated oxid of iron 70 per cent and clay 30 per cent, No. 35. AMERICAN WasHED OCHRE — For the benefit of the Photomicrograph X250, of the same chemist it must be stated composition as French ochre. that when analyses are not given and small percentages of lime and magnesia are found, it is understood that these are natural con- comitants of ochrey earths. FRENCH YELLOW OCHRE French yellow ochre has been used in America for many years, and is analogous in composition to American ochre; but as a general rule the French ochres are more brilliant in shade. Nearly all of the French ochres which are imported into the United States have a composition of about 20 per cent of hydrated oxid of iron and 80 per cent of clay, and one of the most popular brands has for years been known as J. F. L. S. These letters stand for “‘Jaune, Foncé, Lavé, Surfin,’ which mean, “Yellow, Dark, Washed, Superfine.” These, letters are varied 70 CHEMISTRY AND TECHNOLOGY OF PAINTS according to the treatment that the ochre gets, but the J. F. L. S. is the most popular. 7 In color, the French ochres are more brilliant, as has been stated, but the American ochres are invariably finer; but this, of course, refers only to the American grades of equal price. RAW SIENNA Raw sienna differs from ochre inasmuch as ochre is 80 per cent of clay colored red with 20 per cent of ferrous hydroxid. Sienna is al- most the reverse, and con- tains from 30 to 40 per cent of clay, and from 60 to , 70 per cent of ferrous hy- _ droxid. The optical differ- / ence between sienna and ochre is, that sienna when finely ground in oil is trans- lucent and almost trans- a parent. Ochre is always No. 36. J. F. L. S. Ocurr— Photo. Opaque. Sienna is a very micrograph x250, showing crystalline durable color, and very per- ee manent, but must never be mixed with any of the organic lake pigments, for it de- stroys even the permanent lakes, and changes their bril- liancy to a muddy tone. CHROME YELLOW Chrome yellow is chromate of lead, made by mixing a solution of sodium dichromate with a lead solution, gener- ally lead acetate. The lead acetate is usually made by one of these three processes — THE YELLOW PIGMENTS 71 t. Metallic lead in finely divided form is dissolved in acetic acid to saturation. 2. Litharge is dissolved by boiling in acetic acid. 3. Lead acetate is dissolved in water. By regulating the concentration of the solutions, the temperature, and by other manipulation, a wide variety of yellows are produced with various physical characteris- tics and ranging in shade from a very pale primrose to a deep orange. Alkali, usually in the form of sodium car- bonate (soda ash) is added to produce the deeper orange shades, and acid is added to produce the lighter shades. Being of high specific gravity they settle rapidly, and may be washed by decantation without trouble. Sometimes the nitrate of lead is used in place of the acetate. Sometimes the more expensive potassium dichromate replaces the sodium salt to produce clearer colors. All of the chrome yellows are perfectly permanent, provided they are thoroughly washed to free them from residual salts. Manufacturers are now abandoning the old mechanical method of stirring chrome yellow after it is precipitated, and are substituting air stirring, which avoids any possible tendency to produce lead sulphide, the air converting the sulphide into sulphite and sulphate. Chrome yellows when thoroughly washed are permanent to light, but they cannot be recommended where sulphur vapor is generated, owing to the formation of lead sul- phide, traces of which detract from the brilliancy of the color of the pigment. CHROMATE OF ZINC Chromate of zinc has only come into general use within the last ten years in mixed paints and paints generally, on account of its alleged rust-preventing prop- erties when used as a priming paint on steel. 7B CHEMISTRY AND TECHNOLOGY OF PAINTS Chromate of zinc is made as follows: Zinc oxid is boiled in a solution of potassium bichromate for several hours and filtered and dried with slight washing; or a hot neutral solution of zinc sulphate is precipitated with potassium chromate. Chromate of zinc is soluble to a considerable extent in water, and therefore should not be used as a finishing coat, as rain will streak the surface. For example, a green paint made of chromate of zinc and blue shows yellow streaks when exposed to the weather. This material is used to some extent by artistic painters, and as oil paintings are never subjected to the elements it is under those circumstances a perfectly per- manent color. For interior painting and flat wall paints, chromate of zinc, therefore, has an advantage, as much more brilliant tones are obtained and much more delicate shades are obtained than with the chromate of lead. It has very little hiding power or opacity, and in tinctorial strength is much weaker than the chromate of lead. If contained in a mixed paint, when the pigment is thoroughly washed with benzine and freed from oil or medium, chromate of zinc can easily be recognized, be- cause the pigment when shaken with hot water in a test tube is invariably colored yellow. This, however, must be further verified, as barium chromate reacts the same way. YELLOW IRON OxIDs Yellow iron oxids are produced artificially by patented processes and are identical in properties with the manu- factured red oxids. They have become valuable pigments and are often used to replace ochres where brighter and stronger chemically inert yellows are required. They are sold under such trade names as “Ferrite” and ‘‘Ferrox.”’ THE YVELEOW PIGMENTS 73 Chemically these colors are not oxids but consist of 98-99 per cent Fe(OH); the impurities being mainly CaSQ,. CADMIUM YELLOW CdS Cadmium yellow is made by passing a current of hy- drogen sulphide through a solution of any cadmium salt. If the solution is made slightly acid, a yellow shade is pro- duced, and by changing the proportions of acid and adding ammonium sulphide, deeper shades may be made, up to the deepest orange. Change of temperature also affects the shade. A bright vermilion also exists. This is a cadmium selenide. Lithopone, zinc oxid and particularly zinc chromate, are frequently blended with cadmium sulphide in order to match certain shades. Cadmium sulphide is used under conditions where the cheaper bright yellows would fail, its main uses being, in the coloring of vulcanized rubber, as an artists’ color, and for switch and target enamels. It should under no circumstances be mixed with pigments or vehicles containing metallic salts or other substances that react with sulphur. ; Cadmium lithopone is a combination of cadmium sul- phide and barium sulphate. It is made the same way as regular lithopone, the reaction being BaS + CdSO,; = BaSO, + Cds. ANTIMONY SULPHIDE Sb.S; Antimony sulphide is analagous to cadmium sulphide, and is used to some small extent as an artists’ color, and in the coloring of rubber, but for very little else. It is made in two shades, the golden or orange, and the scarlet or crimson. The golden or orange shade is made by the action of hydrochloric acid on potassium sulphantimonate and crim- son or scarlet antimony is made by precipitating a solution 74 CHEMISTRY AND TECHNOLOGY OF PAINTS of an antimony salt, usually antimony chloride or tartar emetic with sodium thiosulphate. Antimony yellows fre- quently contain calcium sulphate and usually contain free sulphur. ARSENIC SULPHIDE As»S3 The arsenic sulphides are similar to the antimony sul- phides and were largely used at one time. At present they are little used except as rubber colors. The yellow shade or king’s yellow (orpiment) is made from arsenic oxid in the same manner as golden antimony is made, and the orange shade or realgar, is made in the dry way by fusing sulphur and arsenic. Both are very poisonous and contain free sulphur. CHAPTER VI THE BROWN PIGMENTS THE principal brown pigments used in the manu- -acture of paint, excepting the aniline lakes, are the burnt siennas, the burnt umbers, burnt ochres, Prince’s Metallic or Princess Mineral brown and Vandyke brown. The siennas have practically the same composition as the ochres, except that they contain more iron and have a small percentage of manganese. The shade of raw sienna is much deeper than that of the darkest ochre, and burnt sienna is a very reddish, light brown. Generally ~ speaking, the finest siennas are mined in Italy. Burnt sienna is much more transparent than raw sienna. The umbers are similar in composition to the siennas, with the exception that they all contain manganese and are of a much deeper brown and do not approach the red. The Princess Mineral brown or Prince’s’ Metallic oxids are calcined carbonates, silicates, and oxids only found in America, and are very largely used, particularly for the painting of wood. Vandyke brown is a very deep brown, and is trans- lucent when finely ground, containing more than so per cent of organic matter. AMERICAN BURNT SIENNA This is a permanent reddish brown pigment made by calcining raw sienna, raw sienna being a hydrated oxid of iron containing clay. When burnt the percentage of Fe.O;, or ferric oxid, ranges from. 25 to 60 per cent, 75 76 CHEMISTRY AND TECHNOLOGY OF PAINTS depending upon the original ore. There is one grade found in the Pennsylvania section which assays as high as 80 per cent ferric oxid, and is known as double strength sienna. This is richer and deeper than the Italian sienna, and when reduced with ordinary clay and ground in oil makes a staining pigment equal to the Italian. From a raw-material standpoint the Italian siennas when tinted with 20 per cent of white show a bluish tint, whereas the 6, American siennas show a LE Le a brownish or yellowish tint, GO Sra Z vote SO apy + and only one who has had Pe 9? wh 88 een | en Da ete 2 a 2 great deal of experience se ¢ *, s é ~~, We ee - He. Sontion £ * 3 4 in tinting out these siennas ee ee srs o Lt € * can tell empirically the dif- *. @& : ie ey ae . oe ae zt ference between an Ameri- ew pe / . : ' Sy oe at So 7 can and an Italian sienna. ee. an * ‘. ye ' The Italian and the Ameri- to ! oe can slennas normally con- ~ 7 cP a ~~. “iyo tain some calcium salts, No. 37. AMERICAN Burnt SIENNA— but occasionally some ores Photomicrograph 250, excellent qual- are found which are free A ery Ss from lime compounds. For paint purposes, however, these are no better than those that contain lime, for many grinders add from 5 to to per cent of whiting to umbers and siennas to prevent them from running or disintegrating when used as stain- ing colors. | ITALIAN BuRNT SIENNA Italian burnt sienna is made from raw sienna, the raw sienna being a hydrated oxid of iron containing clay, in which the iron predominates, the burnt sienna being of the same composition minus combined water. The hydrated oxid of iron is normally yellow, and when THE BROWN PIGMENTS a9 this is burnt the ferric oxid which is produced is reddish or reddish brown. Italian burnt sienna differs from most American burnt siennas in that its ferric oxid content is generally greater. The Italian burnt siennas average from 60 per cent Fe,O; to as high as 75 per cent. The American burnt sienna, known as double strength sienna, which is equal in iron content to the Italian, differs totally in shade, the American being of the order of a Havana brown, the Italian being of a maroon type. Siennas in mixed paints are largely used for their tinting quality, the resulting shade being a yellowish maroon or salmon color of extreme permanence. After several years’ exposure a mixture of white and burnt sienna will darken slightly, but will never fade. Under the microscope a finely ground sienna shows little or no grain. Raw AND BURNT UMBER The chemical composition of the umbers differs slightly from that of the siennas, umbers having a larger man- ganese content. The best raw umber is mined and finished in Italy, and an inferior grade is produced in the United States. Both raw and burnt umbers produce shades and tints that cannot be duplicated by other colors of moderate cost. Burnt umber, like burnt sienna, is more reddish and transparent than the raw product. Burnt umber is a very useful pigment; it is made in the United States and also imported from Italy, Cyprus, and European Turkey. All umbers normally contain over 5 per cent of manganese dioxid, while some of them contain as high as 20 per cent manganese. The Turkey umbers are generally richer in manganese than the Ameri- can umbers. 78 CHEMISTRY AND TECHNOLOGY OF PAINTS A typical analysis of burnt Turkey umber would be as follows: Calcium: Carbonatete 26 sec 0 7% Silica sl ea eee a ee 34% Manganese: Dioxid 22... ee 14% Ferric Oxid shoe ee 42% Alumina . \it/code Sees en 3% 100% A typical analysis of an American burnt umber would be: Silica and-Alumina (clay) 7) eee 60% Ferric: Oxid ..¢ cate .o et ee ee IE Manganese Dioxid. 70.5... 0 8% Calcium Carbonate: soo nn 5%, Carbon and Carbonaceous matter........ 2% 100% These types would indicate that an American umber is not as strong and does not contain as much ferric oxid and manganese dioxid as a Turkey umber. BURNT OCHRE Burnt ochre is distinctively an American color, and differs in physical quality from burnt sienna in so far as the burnt ochre has hiding power and the sienna has trans- lucent or staining power. Burnt ochre is more like a brown paint, and burnt sienna like a mahogany stain. Burnt ochre covers solidly; burnt sienna covers translucently. Some of the American siennas which are not good enough for staining purposes are burnt and find their way to the market as structural steel paints and railroad paints of the brownish red order; as such they are remark- ably good in their protective quality against corrosion. No standard of composition can be given, as burnt ochre varies very much in the percentage of iron, some of the burnt ochres ranging as low as 30 per cent iron THE BROWN PIGMENTS 79 oxid and others as high as 7o per cent, the balance in both cases being clay. PRINCE’S METALLIC OR PRINCESS MINERAL BROWN This is one of the best known paints, and has had a successful career for more than fifty years. It is a very pleasing brown pigment, which has an enormous use all over the United States for painting wooden freight cars and for painting tin roofs. Where it is applied to a flat surface like a tin roof it has been used for many years in its dry state, and mixed with half raw and half boiled linseed oil in the field. It is at times fairly fine, and while it is an excellent preservative for steel it may be regarded as a better preservative coating for wood, two coats on many of the wooden barns in the country in the States having lasted ten years. The analysis of the material varies very much. Geologically, the ore is a carbonate, and lies be- tween the upper Silurian and lower Devonian. It is a massive material of bluish gray color when mined, and resembles limestone, although it contains a very low percentage of lime. The process of mining 1s by shaft-work. -The ore wo, 3g, PRINCE’S METALLIC — Photo- itself lies between two hard micrograph X300. rocks and rarely ever ex- ceeds three feet in width, and as a consequence the mining is an expensive operation. The ore is hauled to the kilns, where it is roasted, which drives off the carbon dioxid and converts it into a sesqui-oxid. The milling 80 CHEMISTRY AND TECHNOLOGY OF PAINTS is the ordinary process used in grinding any of the iron oxids. The material was originally manufactured by Robert Prince of New York, who became interested in a slate quarry located in Carbon County, Pennsylvania, from which locality the original material came. A fair analysis of this material is as follows: Oxid’ of Iron (6:02) a eee 48.68% Silica xc). 6 CSc ee Pee ee avi Alvtiinias.25 2 ose. eee ee 12.007) Lime 0.5 2 ee eee 25027, Magnesian i: Wguccs evn os ae ere 1 e255 Lossonelenition.- Sane ee ee 2.34% Undetermined = 5) 4386 ee 0.26% 100.00% As the material is not alkaline, the lime and magnesia are undoubtedly combined with the silica, so that the material other than oxid of iron is silicate of alumina, lime, and magnesia. Sometimes, the percentage of FeO; will run below 40 and sometimes it will go as high as 50, but this really makes no difference in the paint, and in view of the fact that it is a natural product and may from time to time contain a little gang rock some leeway must be given as regards its composition. VANDYKE BROWN Vandyke brown is a native earth, and is identical with cassel brown. It is popularly supposed that Vandyke first used this pigment as a glazing color in place of bitumen, and as it is composed of clay, iron oxid, decomposed wood, and some bituminous products, it is fairly translucent and adapts itself for glazing purposes. Because of the bitumen which it contains, it dries very badly and very slowly, and has a tendency to crack or THE BROWN PIGMENTS wrinkle if the under-coat is either too hard or too soft. Concerning its permanence, there can be no doubt that it darkens considerably on exposure, like all the bitumi- nous compounds, and many painters use a permanent glaze composed of a mixture of ochre and black tinted with umber. Where the effect of age is to be simulated, there is no objection to its use. This pigment is used in mixed paints, principally on ac- count of its deep shade and. trans- lucent appearance. It contains upwards of 60 per cent of organic matter. No. 39. VANDYKE BROWN X38o. A typical analysis would be as follows: Organic Matter HEC xId oe, Calcium Carbonate Potash and Ammonia Salts NEOISLUECG a So ee 1 “Materials for Permanent Painting” by Maximilian Toch. eae DE Pere RN AE ER esa 65%. fh ee Re eR aes 3% ee ka VE hry OT 5% iD Mee rapes: 2, Weak et ht pe cee 25% 100% CHAPTER VII THE BLUE PIGMENTS THE blue pigments usually used in the paint industry are artificial ultramarine blue, artificial cobalt blue, and Prussian blue. The types of Prussian blue vary very greatly with their manufacture, and are known under the names of Milori blue, Bronze blue, Chinese blue, Antwerp blue, Paris blue, etc. Ultramarine and cobalt blues are permanent to light and alkali-proof. The Prussian blues are permanent to light, but not alkali-proof. ULTRAMARINE BLUE! Ultramarine blue, whether it is artificial or genuine, is chemically the same, with the one difference that the genuine ultramarine blue is the powdered mineral known as lapis lazuli, and ordinarily is the blue known under that name. Furthermore, the mineral itself is found at times in an impure state either admixed with slate or gang rock, or contaminated slightly with other minerals, and the genuine ultramarine blue may run, therefore, from a very deep blue to a very pale ashen blue; in fact, the lapis lazuli which lies adjacent to the gang rock is ground up and sold under the name of ultramarine ashes, which is nothing more nor less than a very weak variety of genuine ultramarine blue. From the standpoint of exposure to light or drying quality, the artificial ultramarine blue is just as good 1 “Materials for Permanent Painting,’ by Maximilian Toch. 82 THE BLUE PIGMENTS 83 as the genuine, and the only advantage that the genuine has over the artificial is that the genuine is not so quickly affected by acids as the artificial is. It may be of interest to know that in 1814 Tessaert observed the accidental production in a soda oven at St. Gobain (France) of a blue substance which Vanquelin declared to be identical with lapis lazuli. In the following year the same observation was made by Huhlmann (at St. Gobain in a sulphate oven) and by Hermann in the soda works at Schoenebeck (Prussia). PRES ae In 1824 La Société d’Encouragement pour Industrie offered a prize of 6000 francs for the production of artificial ultramarine blue, which, in 1828, was awarded to J. B. Guimet, a pharmacist of Toulouse, later of Lyons, who asserted that he first produced ultramarine in 1826. Vanquelin was one of the three “trustees,” holding the secret contrary iG the ule ors thesocicre. In=Decembergers2a, Gmelin of Goettingen ex- No. 41. Urrramarrne Bie, ground in plained his process of mak- eee eectopiaph | X42: ing artificial ultramarine before the Académie des Sciences of Paris. He used as 84 CHEMISTRY AND TECHNOLOGY OF PAINTS the basis a mixture of precipitated hydrate of alumina and silex, which was later on superseded by China clay (kaolin). In 1829 Koettig produced ultramarine at the Royal Saxon porcelain factory at Meissen. In 1834 Leverkus, at Wermelskirchen, and later at Leverkusen, on the Rhine, produced the pigment. In 1837 Leykauf & Zeltner, at Nueremberg, introduced the manufacture of ultramarine into Germany. Prices of ultramarine in 1830: Nev evita. or eee se eee $50.25 per pound Artiicral aces eee 4.05 per pound Ultramarine is composed of alumina, silica, soda, and sulphur, as follows: Ultramarine (pure blue) containing a minimum of silica seems to be a more or less well-defined chemical body, i.e., a double silicate of sodium and aluminium with sulphur as a poly-sulphide of sodium, or as a thio- sulphate. Ultramarines Poor Rich in Silica in Silica Alumina... (ee sor. ee ee 20/00) e227 70 Silica Se oe bee ee 38.50 40.80 Sodas) Rohe Mere. sevens te 22,50) (456.40 Sulphuter eee. ae oc, se 8.201, E60 Undecomposed iin ees 1.80%, a2ebo I00.00 [00.00 R. Hoffman gives the following proportions: Alumina — Silica Pooranisilies a eee 100 128 Rich in.silica 2 eee eee 100 170 THE BLUE PIGMENTS 85 In resistance to alum the different products rank as follows: ANUS) 1 and TE Sai apace aa any Sere First Artif. Ultramarine (rich in silica). ... Second Artif. Ultramarine (poor in silica) ... | Third In 1859 Leykauf discovered the purple and red varie- ties of ultramarine, which were produced by the action of hydrochloric and nitric acids, and by heating ultra- marine with calcium chloride, magnesium chloride, and various other chemicals. In this way there were pro- duced a variety of shades, and by the addition of such substances as silver, selenium, and tellurium, even yellow, brown, purple, and green shades were produced. All of these colored ultramarines are exceedingly permanent to light, but have little or no hiding power, and when used alone are perfectly permanent. The ultramarine blue which is made by means of a potash salt instead of a soda salt has every analogy of color and shade to genuine cobalt blue, excepting that the genuine cobalt blue is not affected by acids as rapidly as the artificial. ARTIFICIAL COBALT BLUE The cobalt blue of commerce is the same as _ ultra- marine blue, the difference being in the shade. Ultra- marine, when mixed with thirty parts of a white pigment, such as zinc oxid, produces a violet shade, whereas the cobalt blues when mixed in the same proportion produce a turquoise or sky-blue shade. Chemically, the com- position of these ultramarines and cobalts will average about 50 per cent silica, 22 per cent alumina, 15 per cent sodium sulphide, in combination with 3 per cent water and ro per cent sulphur. The addition of the slightest 86 CHEMISTRY AND TECHNOLOGY OF PAINTS trace of acid to a paint containing ultramarine blue liberates H.S, which always indicates the presence of ultramarine in a blue or bluish pigment. Under the microscope ultramarine blue has a distinct crystal- line appearance. When these crystals are badly de- stroyed by fine grinding the color suffers very much, the characteristic brilliant blue of ultramarine becoming an exceedingly muddy shade. Its tinctorial power is very weak, but it is exceptionally permanent to light. In blue shades of mixed paints the percentage of ultra- marine blue can be deter- mined either by difference or by the percentage of sulphur “present. aie per cent is accepted as the amount of sulphur in ultramarine blue, a fairly accurate quantitative de- termination can be arrived at. Where ultramarine blue No. 42. Dry ULTramarine BLUE— is mixed with lithopone the Photomicrograph X320. zinc sulphide of the litho- pone as well as the ultramarine evolve H.S. When deter- mining the ultramarine, the total H.S evolved must be calculated as sulphur. The zinc must be precipitated as carbonate and weighed as oxid and calculated to sulphide. The sulphur in the ZnS must then be deducted from the total sulphur. From the difference the percentage of ultramarine blue in the original pigment may be cal- culated. . As ‘acetic acid a neutral ferric oxid, con- A ee i . taining in its composition 75 per cent ferric oxid and ee ‘s tn. * 20 per cent silica “mixed 2 : : & - with graphite containing 85 %, ie ® per cent graphitic carbon, » ai as as has proved itself to be as , : : good a paint as can be be, ey TS desired for ordinary pur- eesce ot poses. The pigment in a No. 46. NATURAL GRAPHITE — 90 per : : : ; cent carbon, very finely powdered. paint of this kind will withstand the chemical ac- tion of gases and fumes, but the oil vehicle is its weakest part. Since the electro-chemical industry has been developed at Niagara Falls graphite has been made artificially and is sold under the name of “Acheson Graphite.” This graphite is to be commended as a paint material on account of its uniformity and fineness of grain, but it should not be used alone as a pigment, for as such it possesses the physical defect of lightness just described. A graphite paint containing more than 60 per cent graph- THE BLACK PIGMENTS IOI ite does not serve its purpose very well unless 4o per cent of heavy pigment is added, such as a lead or a zinc compound. A rather unfortunate defect in the graphite paints containing a large amount of graphite is the smooth and satin-like condition of the paint film, which is poorly adapted for repainting. It has often been noted that a good slow-drying linseed oil paint will curl up when applied over certain graphite paints, because it does not adhere to the graphite film. On the other hand, if particular forms of calcium carbonate, silica, or ferric oxid are added to graphite a surface is presented which has a | “tooth,” to which succeed- 4 ing films adhere very well. The question of the co- efficient of expansion in paints has not been thor- oughly considered, and firs many a good paint will No. 47. ARTIFICIAL GRAPHITE (Acheson) fail because it is too elastic. | ——Photomicrograph 250, contain- ‘ ; ing go per cent of carbon. Engineers sometimes pre- | fer a paint which when scraped with a knife blade will curl up like ribbon. Priming coats suffer very much when they are as elastic as this, but the paint chemist can overcome these defects by the proper ad- mixture of inert fillers and hard drying oils. Graphite is known as a very slow drier, but this is true only when too much graphite is used in the paint. There is no reason why a graphite paint should not be made to dry sufficiently hard for repainting within twenty-four hours. | 102 CHEMISTRY AND TECHNOLOGY OF PAINTS CHARCOAL It is not generally known that charcoal from the willow, maple, and bass trees is largely used as a pigment for black paints. ‘There are a number of black paints on the market which are composed of charcoal, lampblack, litharge, and linseed oil in varying proportions, and in the early history of these paints it was difficult to make them so thin that they would not turn semi-solid in the package. It was found that aS a preservative coating on steel they did remark- ably well. Investigations _ by the author have shown © that this preservative ac- tion is incidental and is due entirely to the alkali contained in the charcoal. _ / Some of the charcoal used aS et” is a by-product from paper No. 48. ARTIFICIAL GRAPHITE (Ache- mills and contains as high son) — Photomicrograph X250, umi- as g per cent of potassium eee carbonate? im? tact een. carbonate is produced by the burning or calcining of wood, most charcoal being more or less alkaline. In the exami- nation of paints of this character it was noticed that the spectroscope showed the potash lines, and thus it became a very simple matter to determine by means of the spectro- scope whether a paint was a charcoal paint or not. The author has demonstrated on previous occasions that the oxidation of metal cannot take place in the presence of certain alkalies, and therefore these charcoal paints when freshly made are excellent preservatives for the metal. But, inasmuch as moisture is always present in these paints, THE BLACK PIGMENTS 103 having been added in the form of water or contained in the raw materials, saponification takes place more or less rapidly, so that the paints are sometimes unfit for use two months after they are made. The charcoal above re- ferred to, which is the by-product from the paper mills, while not so suitable for the manufacture of mixed paints, has, however, been very largely used in the manufacture of oilcloth No. 49. Five CHARCOAL — Photomicro- and coated leather. graph x600. VINE BLACK In all essentials this pigment is the same as the pow- ' dered charcoals for paint purposes, excepting that the grain is smaller and the black denser. It is made in Germany by charring the grapevine. If over- charredi ites ismdikely: 3to become too alkaline. The same tests may be applied to this black which were used for all the charcoal and wood pulp blacks, the No. so. CHarcoaL BLack — Photomi- crograph x600, showing hexagonal simplest and most effec- structure of the wood. tive test being to boil the black in water, filter, and add a few drops of phenol- phthalein. 104 CHEMISTRY AND TECHNOLOGY OF PAINTS GOAT Powdered anthracite and bituminous coal are likewise used in black paints, but the origin of their use is due to some extent to poorly written paint specifications. An engineer will at times prescribe a paint containing a cer- tain percentage of ash, and in order to meet this require- ment a paint manufacturer will have to add coal in order to conform with the requirements, but as sulphur com- pounds such as SO, and SO; always exist in coal a paint is produced which is ex- ceedingly harmful to metal. Ivory BLACK Ivory black is still used to some extent for very intense coach colors, and there is alsoSas every enme AE species of carbon black on No. 51. VINE Biack (German make) — the market known as the fee ee X250, two sizes of “Extract of Ivory Black,” : which is made by digesting charred ivory chips in hydrochloric acid until nearly all of the calcium phosphate is dissolved. Such a black has intense staining power, and is by far the blackest material made. It is very expensive, colloidal in its nature, and used therefore for ready prepared color-in-varnish or high grade black enamels. DROP BEAGK Drop black is generally made by calcining sheep bones, which are then impalpably ground in water, and when in THE BLACK PIGMENTS 105 paste form cast into small drops; hence its name, ‘‘ Drop Black.” These cone-shaped drops were largely used twenty-five years ago, and then were an indication of a good black, but at present the name “Drop Black” still clings to finely powdered bone black. So-called drop black is generally composed of from to to 20 per cent of carbon and from 80 to go per cent of cal- cium phosphate, and is sold entirely for its intensity of blackness. BLACK TONER Black toners may be either the extract of ivory black, the extract of bone black, or certain forms of carbon black, or carbon black upon which nigro- sine has been precipitated. Another method for mak- ing black toner is_ to precipitate red, yellow, and blue aniline upon the ex- tract of ivory black, which produces an_ intensely black pigment that is flocculent and remains in suspension a long time. No. 52. Woop Purtp Brack — Photo- The principal difficulties micrograph 500, very fine uniform with these coal tar blacks, however, are: first, they are not really black in the sunlight; and second, they paralyze the drying quality of any varnish with which they may be mixed. There are a number of specially fine blacks that can be used for black toners, such as condensed carbon from benzol or acetylene. Benzol black is remarkably fine and intensely 106 CHEMISTRY AND’ TECHNOLOGY OF PAINTS black, and inasmuch as there may be an overproduction of benzol in the United States within. the next few years it is very likely that benzol black will become a reasonable article of commerce. BENZOL BLACK Benzol black is a carbon black which, however, ‘is much better than the car- bon black produced from natural gas. It is soft, contains no granular par- ticles, and remains in sus- pension for many weeks in both oil and varnish. It is, however, a very poor drier, like most of these blacks, and therefore a mixture of litharge and red lead oil is recommended when they are to be used. No. 53. Drop Brack — Photomicro- graph x<300, not very uniform. ACETYLENE BLACK This black is not quite as common as it was some years Sa NY ANTI-FOULING PAINT 65 gals. Shellac Varn. 15 lbs. Zinc Oxid 4 Gee en Alc: Slee Blancsbhixe Pete eee aie Lar 25 ‘‘ Indian Red fae el urps, — 10 “© Red Oxid Mercury Yield : T5 gals. The copper paints which are found on the market con- tain from to percent copper scale (copper oxid — Cu,.0) to as high as 4o per cent. As a rule, this is added in a very fine powder to a mixture of linseed oil, pine tar, benzol or gas house liquor, and oxid of iron in some form, usually of the Prince’s Metallic type, is added as a pigment for hiding power. This is a so-called red or brown copper paint. The green anti-fouling is generally a copper soap manufactured by saponifying either linseed oil, tallow or fish oil with caustic soda, and then adding sulphate of copper to this soap, which produces an oleate or linoleate of copper and sulphate of soda as a by-product. The sulphate of soda is washed out, the remaining water boiled off, and then pine tar and linseed oil added to the mixture together with chrome yellow and Prussian blue for hiding power. This yields a semi-drying or non- drying type of green anti-fouling, which in many instances has given excellent results, but which in some tropical waters does not show up as well as the oxid of copper paint. The copper paints do not show up as well as the mercury paints. : There is a third type which is not a paint, but which is really a soap that is applied hot. Oleate or linoleate of copper mixed with China wood oil when melted and applied to a thickness of about 4's to § of an inch has given very good results, and it is stated that this type of copper paint is a happy medium and possesses both the exfoliating and the poisonous qualities so much in demand. 152 CHEMISTRY AND TECHNOLOGY OF PAINTS CONCRETE OR PORTLAND CEMENT PAINTS Portland cement is an alkaline rock-like substance, which after it has set liberates lime. The literature is replete with statements that Portland cement floors cannot be painted, and it was not until 1903 that the first successful experiments were made for the painting of Portland cement. Prior to that time all sorts of things were recommended, such as strong acids like sulphuric acid and acetic acid, but it was soon found that the application of acids of this type to Portland cement destroyed the Portland cement because it dis- solved out the lime and left the sand and aggregate loosely bound. Portland cement floors “‘dust”’ up under the abrasion of the heel, and until a successful method for painting them was found it was impossible to use them in an uncovered condition. In power houses where delicate electrical machinery was placed the contact points were ground out by the silicious matter floating in the air through abrasion of concrete under the feet. The ac- companying photomicrographs show the appearance of a Portland cement floor highly magnified, and indicate in a general way the necessity for painting Portland cement. In warehouses, storerooms and offices generally, concrete floors. had to be covered with linoleum or wood to prevent this continual dusting, which became obnoxious. The paints made of drying oils were readily saponified and gave unsightly effects, and it was not until the publication of a patent on this subject (U. S. Letters Patent No. 813,841) that the trade in general began to understand that a resin acid was necessary to combine the lime and not destroy it. Previous attempts had been made depending upon the destruction of the lime, MIXED PAINTS 153 but in this patent it was first shown that a chemical reaction took place and the lime instead of being de- stroyed was made to serve a useful purpose. A resinate of lime was formed when the coating applied had a sufficient acid number. The amount of free lime in concrete is not very great, for in a 1:3 mixture, that is, a mixture containing one part of cement and three parts of sand, the top sur- face varies in composition from 0.87 to 1.6 per cent of free lime. A large number of analyses were made by the author, and it became obvious that an acid num- ber of 5.0 is sufficient to more than neutralize the amount of lime present, and once neutralized dust- ing does not take place. It is well known that con- - crete of any kind and of . ee. any mixture is rapidly No. &. Photomicrograph of Portland disintegrated by paraffin cement floor composed of 2 parts sand 7 and 1 part cement. This floor is po- or machinery oils and re- rous and will disintegrate rapidly unless duced in time. 3 Ee how- properly treated with a cement floor paint. ever, the cement filler or neutralizing liquid is composed of China wood oil and a hard resin like copal, the resulting calcium resinate becomes insoluble in oil, so that oil dripping on a floor of this kind does not disintegrate the Portland cement. Oil collecting on an unpainted concrete floor will cause the floor to become as soft as cheese in time, and then there is no remedy for it excepting to take up the floor and put down a new one. There is no record that China wood oil and copal had ever been used on Portland 154 CHEMISTRY AND TECHNOLOGY OF PAINTS cement floors prior to the application in question, and that this patent was new and useful is demonstrated by the fact that there are practically at this writing over forty Portland cement paints on the market, all of them based on the same theory. In 1910 it was suggested that zinc sulphate be used to overcome the pernicious action of the free lime in Port- land cement, and for a time this material had quite a vogue, but it has turned out that no man could tell how much zinc sulphate to use, for no man knew definitely the amount of free lime in any large area of Portland ce- ment, and therefore either too much or too little was used. If too little was used there was still some free lime left; if too much was used sulphate of zinc crys- tallized out, and when the wall or floor became wet, either through rain or through washing, the film No. go. Highly magnified view of a fine crack in Portland cement con- of paint peeled off. struction —an example of incipient Practically all the paints disintegration. for Portland cement that — are on the market contain either China wood oil or a copal resin or both. Those composed of both of these materials have given the best satisfaction. Where ten years ago there was only one of these paints on the market today there are a large number, and it 1s estimated that more than a million gallons per year at this writing are used for the surface protection of Portland cement. MIXED PAINTS Iss PAINT CONTAINING PORTLAND CEMENT There is only one paint in existence thus far that contains a material equal to Portland cement, which is a tricalcium silicate and dicalcium aluminate, and which on setting liberates lime. This paint is known as “Tockolith,” and it has been and still is very largely used among engineers for the protection of steel against corrosion. The author cannot go into this subject any more deeply because this discovery is his and he is interested in the manufacture of this material, and furthermore, this book is not the place to exploit a proprietary article; but inasmuch as this paint has been regarded by many engineers as at least a step toward the solution of the question of the protection of iron and steel, it is fitting that this brief mention of the material should be made. DAMP-RESISTING PAINTS Paints of this character are comparatively new, the first one having been manufactured by the author’s firm and put on the market in 1892. It was made for the purpose of coating brine pipes and pieces of machinery which were continually under water. ‘The original paints of this character were produced by melting a good grade of asphaltum and adding a sufficient quantity of gutta- percha together with a suitable solvent and a small per- centage of pigment. These paints served their purpose very well and were used very largely, but no matter how carefully compounded the gutta-percha separated from the asphalt base if the paints were allowed to stand for any length of time. 156 CHEMISTRY AND TECHNOLOGY OF PAINTS Further experiments showed that cement mortar would adhere most firmly to such a paint. The paint could be applied even to a new brick wall, lathing and furring being omitted. It took such a long time, however, to introduce a paint of this character to the building public that the author’s firm never thought it worth while to patent the application. Damp-resisting waterproof paints are now an adopted fixture in the paint industry, and while bitumen forms the base of paints of this character, treated China wood oil, and treated linseed oil in which glycerine is replaced with a suitable metallic base, should be added when making these paints. They are used widely and in various ways, having served their purpose so well that engineers are beginning to adopt such paints as priming coats for metallic structures wherever cement or cement mortar is to be applied, so that oxidation by electrolytic action may be prevented. ENAMEL PAINTS Enamel paints in former years were pigments ground in varnish, which dried with a high gloss. Some people objected to this high gloss, and where a good grade of varnish was used the film was rubbed with pumice stone and water until it produced an egg-shell finish. This then led to semi-gloss enamel paints, and finally we have the misnomer of having perfectly flat enamel paints today, for the very word ‘‘enamel”’ indicates gloss. For decorative use the principal enamel paints are white, but it must be said at the outset of the chapter that this subject cannot be thoroughly treated in this book. It has become so vast that it would take a book of this size alone to do the subject justice. There are MIXED PAINTS 157 vast quantities of enamel paints made which are colored, but these are principally used for machinery of all kinds, for automobiles and for the so-called enamelling of various utensils, such as tool handles and the like. There are also vast quantities of black enamels made for technical purposes, and these are used for the manufacture of oil- cloth, patent leather and mechanical appliances. Those for oilcloth and patent leather are true oil enamels; those for mechanical appliances are principally made on an asphalt base. This chapter will treat of the subject of enamel paints for decorative purposes, which are principally white and mainly based on zinc oxid ground in a varnish or varnish oil. Prior to the mixed paint era white enamel was made by taking zinc oxid ground in either poppy oil or a bleached linseed oil, and thinning it with damar varnish as it was needed, and the painter did this himself. But as ready for use enamels were demanded improve- ments were made on this type of material. Today the three types of white enamels are: First. The zinc oxid types ground in damar varnish. Second. The lithopone types ground in China wood oil and rosin varnishes. Third. The zinc oxid types ground in stand oil only.! The damar type first mentioned is simple to make, but produces an enamel which does not flow out, which sets very quickly and which sometimes settles hard in the package and sometimes does not, depending entirely upon the gum damar used for the purpose. There are a great many varieties of gum damar whose acid figure ranges from 8. to 26., but the acid of gum damar is very weak | as compared to the acid of the majority of copals, and 1 Stand oil has been described on page 184 in the chapter on Linseed Oil. 158 CHEMISTRY AND TECHNOLOGY OF PAINTS: does not readily unite with a base Jike zinc; therefore a damar type enamel remains in suspension for several years. For enamel purposes damar varnish is usually cut cold, that is to say, six pounds are dissolved in a gallon of solvent in an ordinary vessel at room temperature; the resulting varnish is always cloudy, due to occluded water in the damar. To remove the latter the cold-cut damar is placed in a steam-jacketed kettle and heated to about 220° with steam under pressure. Steam at atmos- pheric pressure has a temperature of 212° F., so that at least ten pounds pressure is necessary in a steam-jacketed kettle to drive off the moisture contained in damar; but when this is done the damar darkens unless the operation is carried out in an aluminum or silver-plated kettle. Such solvents like cymene, toluol and xylol are added up to 5 per cent to damar varnish to overcome the cloudiness with fairly good results, but the action is not immediate, and the damar must be tanked for a con- siderable time. The second type, or lithopone and China wood oil- rosin varnishes, are very good for household use, but not so good for painting furniture, unless the varnish is made by an expert varnish maker with a minimum amount of rosin and the maximum amount of China wood oil, otherwise varnish of this type becomes hygroscopic in damp weather or sticky in hot weather. White pigments other than lithopone are not recommended for enamels of this type because of the high acid figure of the varnish. The third type, in which stand oil or linseed oil and zinc oxid are used alone, is the popular type of today, but has the disadvantage of drying slowly, yet this type of enamel will last for many years, and stands exposure even in the American climate for about eighteen months. It is made as follows: MIXED PAINTS 150 Ten pounds of zinc oxid are ground in ordinary raw linseed oil, and this paste after having been finely ground two or three times is mixed with one gallon of stand oil, and then a gallon or less of turpentine or a mixture of turpentine and turpentine substitute is added. When made in this manner it takes 110° F. of heat four or five hours to dry it so that it is free from tack. Another method is to grind ten pounds of zinc oxid in japan drier, which may be a drier made of resinate of manganese and lead, and then add ten pounds of this paste to one gallon of stand oil. This will air-dry in five hours, and while it gives good results for interior pur- poses it is not recommended for exterior use. A third method of making these enamels is to grind the zinc oxid together with the stand oil in a roller mill, and then reduce with the necessary quantity of diluent and drier and strain very carefully. All enamels made along these lines have a tendency to turn yellow in the dark. Some, in fact, turn exceed- ingly yellow —almost the color of beeswax — depending upon the amount of chlorophyll or green coloring matter in the original linseed oil, and no method has yet been devised whereby this can be prevented. Many experi- ments have been made by the author tending toward improving this with partially good results, such as, for instance, the addition of an oxidizing material like hypochlorite of lime to the enamel. From the foregoing it is clearly evident that enamel paints may be nothing more or less than pigments ground in boiled linseed oil without the addition of any resin or gum, and the effect produced is that of high gloss and flexibility. 160 CHEMISTRY AND TECHNOLOGY OF PAINTS FLAT WALL PAINTS Flat wall paints have come into existence in the United States, and it is estimated that hundreds of thou- sands of gallons are now made yearly, and that they give excellent results. Most flat wall paints contain lithopone as a pigment, the photogenic quality of which does not play a great réle in interior painting. Many of the flat wall paints contain as high as 20 per cent of water in the form of an emulsion, as is the case where the water is admissible in mixed paints; for in England the flat wall paints which are sold under a different name, either in paste form or ready for use, are all white paints containing a small percentage of linseed oil, and are the reverse practically of the American type of paints. They are called washable in England when they are washed from the bottom up, for when they are washed from the top down and the water streaks the wall there is danger of dissolving some of the paint and producing a bad effect; whereas the American types of wall paints, even those that contain 20 per cent of water, withstand the action of washing either from the top down or from the bottom up. There are, of course, many types which contain no water, the principal vehicle for this type of paint being a semi-fossil damar mixed with linseed oil or more generally a rosin-China wood oil varnish containing over 50 per cent of solvent. Many of the failures of the flat wall paints which peel and disintegrate are due to the sizing on which they are painted. Glue, shellac or cheap varnish sizings are generally worthless on plastered walls, while an oily resin acid type of filler gives results which are permanent. MIXED PAINTS 161 FLoor PAINTS Wooden floors are painted as a rule with a varnish paint which dries hard over night and produces a wear- resisting waterproof surface. In composition, paints for wooden floors are analogous to paints for concrete floors, -and are composed of a minimum amount of oil which dries by oxidation and a maximum amount of hard resin varnish. ‘The rosin varnishes, particularly those of the China wood oil type, do not wear as well as the hard resin varnishes. The pigments used in floor paints do not play a great role. Numerous experiments made show, for instance, that zinc oxid is not a useful pigment for the reason that the acid number of a floor paint varnish is sufficiently high to combine with the zinc and form an unstable paint —one which thickens up in the container and becomes unfit for use in a few months. Therefore lithopone is found very useful, and the inert pigments are preferred also for this reason. SHINGLE STAIN AND SHINGLE PAINT Shingle stain is not to be confounded with shingle paint. A stain for shingles is translucent; a paint for shingles is opaque, and the difference between the two is quite marked. One shows the grain of the wood, and the other gives a painted effect and does not show the grain. There is hardly any difference between shingle paint and the average ordinary mixed paint, with the exception that some manufacturers add asbestine in order to give it some fire-resisting quality. On this point it is well to mention that shingles that are painted, par- ticularly with a paint that has a fire-resisting quality, 162 CHEMISTRY AND TECHNOLOGY OF PAINTS are superior to those coated with shingle stain, even though they may not look as artistic, because sparks flying from a chimney on a roof that has been stained and has thoroughly dried out are very likely to ignite the roof. Shingle stain is generally made from the very brilliant pigments and crude creosote. These pigments are as a rule ground in linseed oil, and two pounds are generally added to a gallon of creosote. Ordinary creosote oil is used for this purpose, probably because it has some wood preservative quality. Other manufacturers use ordinary kerosene and take two pounds of the strongest colors in oil that they can get. Still other manufacturers use crude carbolic acid or crude cresol and kerosene, but in spite of all these treatments shingles rot just the same. It is the soft pastel effect which a shingle stain gives that commends it so highly; but the same pastel effect is produced with shingle paint after the lapse of a year or two,. provided a good paint is properly reduced with about 50 per cent of volatile solvent. On new work shingles are generally dipped. A bundle is taken and dipped into a barrel and allowed to soak so that the wood will absorb all that it can. On old work, of course, it must be applied with a brush. Asbestine is frequently added in the proportion of one pound to the gallon of shingle stain containing heavy colors to prevent them from settling. One of the most difficult shingle stains or shingle paints to produce is a permanent red. For this purpose the oxids of iron (Fe.O;) are used, but wherever oxid of iron is exposed to the sunlight in the presence of linseed oil or other organic oils it probably changes to a ferroso-ferric condition, becomes considerably darker and is converted into a brown. This is less noticeable in a shingle stain than it MIXED PAINTS 163 is in a shingle paint, because the shingle stain is largely composed of a volatile solvent, and the small amount of binder has relatively a lesser action than the binder in the shingle paint. It has been suggested, and there is probably some value to the suggestion, that potassium ichnomate to the extent of one ounce to the gallon should be ground in crystalline form with the paint in order to prevent any reduction. Hypochlorite of lime has also been suggested, and of the two the hypochlorite would be the better as long as it would last, because it would not wash out and be likely to stain the building. Dichromate would be very likely if it ran over the gutters or leaders to produce a bad stain. CHAPTER XII LINSEED OIL Tuts oil is still the principal oil used in the manu- facture of paints, and within the last ten years very extensive work has been done on the constants and specifications for linseed oils generally, as will be noted from the reports of the American Society for Testing Materials and several other reports quoted by the author. The raw linseed oil produced in the United States comes principally from the northwest. The foreign oils come from Calcutta, the Baltic, and the Argentine regions. There is considerable difference between these oils, the Baltic being perhaps the best and very highly prized by varnish makers. The constants of linseed oil show very wide variations; for instance, its specific gravity will run from 0.931 to 0.935. Its iodine value will vary from 160 to 195 or more, while the saponification value will run between 190 and 196. The greatest differences are found in North American linseed oil, the figures being sometimes so perplexing that it is difficult to reconcile them with the standards of Baltic oil. These discrepancies are easily traceable to the natural impurities found in Ameri- can linseed oil, as, for instance, oils from weeds growing in the flax fields. American linseed oil is likewise inclined to show the presence of water to a greater extent than fore gn oils, but this, however, is a question of age. If raw linseed oil is allowed to settle until it becomes perfectly clear and shows no sediment or tur- 164 LINSEED OIL 165 bidity at o° C., it cannot be said to contain water. The question here naturally arises as to the use of the term “pure.” Calcutta and the Baltic seed are freer from foreign seeds than the American product, and although the amount of foreign seeds which appear as weeds in the field is very small, their presence alters the chemical and physical characteristics of the American oil. Taking Baltic as a standard, it could be reasonably argued that American linseed oil is adulterated, yet no man would have a moral or legal right to condemn American linseed oil because it differed from the Baltic. On the other hand both climate and soil have a well- known influence on vegetation; even the percentage of oil derived from a given seed cannot be said to be constant. It is also stated that virgin soil produces better seed than a replanted field and this statement appears reasonable. To how great an extent the natural or negligible admixture of the oil from foreign seeds to linseed oil affects the wearing quality of the oil, it is impossible to say, but it must be admitted that an oil containing up to 3 or 4 per cent of the oil of foreign seeds or weeds will not act as well in the kettle for varnish or boiling purposes as a purer oil. Taking these facts into con- sideration, a chemist must beware of giving an opinion as to the quality of linseed oil, and where there is no evidence either chemical or otherwise that the oil has been intentionally diluted with other materials no adverse opinion should be forthcoming. If the exam- ination of linseed oil shows an appreciable percentage of paraffin oil, it can. be positively inferred that no weed growth had anything to do with this adulterant and the mixture must be regarded as intentional or accidental. 166 CHEMISTRY AND TECHNOLOGY OF PAINTS Raw linseed oil is extracted from the seed by the old-fashioned method of grinding the seed, heating it, placing it between plates and then pressing it until the remaining cake contains the least possible quantity of oil. The newer method is a continuous process by which the seed is ground and forced in screw fashion through a tube, the oil oozing slowly through an opening in the bottom of the tube and the cake falling out at the end in flakes. When the seed is fed in this manner without heating, a better quality of oil results. The third method consists in crushing the seed and extracting the oil by means of naphtha. The resulting liquid is evapo- rated, the naphtha recovered and the oil sold for painting purposes. It appeared, however, that this process, while very profitable for the manufacturer, was not profit- able for the consumer, and although it made a very fair paint oil, it was found that for the purpose of coating leather, oilcloth, and window shades, the oil had the unfortunate faculty of soaking through the fabric, and when a piece of goods was rolled up too soon and allowed to stand for the greater part of the year it was almost impossible at the end of that time to unroll the goods, the whole having become a solid mass. Inves- tigation showed that some of the proteids in soluble form were extracted by the naphtha. This was called “new process oil,” and it was generally understood that cake made from new process oil was not as good cattle feed as cake made in the old-fashioned way, probably on account of the removal of part of the proteids. If linseed oil were uniform, both as to source and nature of seed, a chemical formula could be established for it, but because it is not uniform the acids cannot be given in quantitative relation. Linseed oil should give no test for nitrogen; if it does, the proteids in the LINSEED OIL 167 seeds have been attacked. Probably 95 per cent of all the linseed oil made is sold in the raw state, and, strange to say, probably 95 per cent or over of all the linseed oil used is consumed in any other but the raw state. It must not be inferred that all paint manufacturers manipulate or treat their linseed oil by heat and other methods of oxidation, for, whilesmany of them claim to do so, not one that the author is acquainted with could afford to handle and manipulate linseed oil. At the same time, raw linseed oil cannot be used for the purpose of making paints unless a drier be added, and from the very moment that the drier, either in the nature of a siccative oil, resin, or Japan, is mixed with the oil, the chemical constants of the oil are altered. The change is an irreversible reaction. As an example, it may be cited that if 90 per cent of linseed oil be mixed with to per cent of volatile constituents and Japan driers, the chemist cannot separate the three substances and produce three vials containing raw linseed oil in the state in which it was used, and the drier in an unaltered condition. The volatile solvent, if it be benzine, is the only one of the three that can be recovered in any approach to its original condition. The literature on- raw linseed. oil is very incomplete, and more attention should be paid by chemical experts and writers to the subject of identification of linseed oil as it really exists in the paint. In the chapter on the “Analysis of Oils” it will be seen that when the iodine number of an oil is 180 the same oil when extracted from mixed paint may show IIo and still be absolutely pure, for the reason that the metallic salts which have been added to the oil in the form of Japan or other siccatives have in a measure saturated some of the bonds of the linseed oil, so that less iodine or bromine is absorbed. 168 CHEMISTRY AND TECHNOLOGY OF PAINTS Linseed oil dries by oxidation, and this oxidation is hastened by the addition of bases or salts of lead and manganese. There is no doubt that some of these act catalytically, and there is likewise no question that some of these driers continue to act long after the oil is phys- ically dry. In drying, raw linseed oil is supposed to absorb as much as 18 per cent of oxygen, but in actual practice where solid linseed oil is used as an article of commerce it seldom absorbs more than to per cent of its original weight. The addition of a drier has much to do with the life of a paint, there being no two driers that act exactly alike. If it is the intention of the paint manufacturer to make a paint that will last the longest, he must study the chemical and physical characteristics of the drier which he uses. Red lead (Pb;O,;) added to linseed oil at a temperature up to 500° F., will make a very hard drying film which in time becomes exceedingly brittle. This can be very easily demonstrated if the red lead oil be coated on cloth and its effect closely watched. On the other hand, the addition of litharge to linseed oil produces the opposite effect, and an exceedingly elastic film is produced. The various manganese salts all act differently and are frequently used to excess. Manganese starts the drying operation, the lead salts continue it, and the manganese again hastens the end. Borate of man- ganese is, perhaps, the least objectionable of all man- ganese salts, but the black oxid or peroxid is most largely used, and if not used in excess is an exceedingly valuable assistant in the drying of linseed oil. These driers are usually prepared by adding the oxids of lead and manganese to melted rosin. After a resinate of lead and manganese is produced, a small quantity of linseed oil is added and the mixture then cooled either with turpentine or benzine or both. There are hundreds LINSEED OIL 169 of varieties of the so-called Japan driers, the best ones containing the minimum amount of rosin and a certain percentage of the dust of Kauri gum. The oil driers are made in a similar way, excepting that no rosin is used, and these driers do the least harm. Lime is very frequently used in addition to oil, sometimes in con- junction with rosin and sometimes alone, in order to produce a drying effect. The so-called lime oil will dry with a hard and brittle film. The salts of lead and man- ganese are not as good for mixed paint purposes as they are for technical purposes. The chloride of manganese when added to linseed oil reacts upon it, and in the presence of any moisture in the oil will liberate traces of hydrochloric acid. Sulphate of manganese and lead acetate will act similarly, and wherever there is a trace of liberated acid in paints their rapid and uniform drying is interfered with. Zinc sulphate and lead sulphate are also excellent driers. It is considered good practice to add a small amount of calcium carbonate wherever these driers are used in order to neutralize the acidity, and when this is done no ill effect can be observed. Prob- ably the most flexible drier is Prussian blue, which is soluble in linseed oil at 500° F., and produces such a flexible film that the patent leather industry is based upon it. Some twenty-three years ago the author manufactured a new drier which is an improvement on Prussian blue. Briefly described, this drier is made out of a by-product Prussian blue which is treated with an alkali in the presence of calcium oxid and water. A brown powder is the result, which has no uniformity of color but has given excellent results as a drier. This brown has been erroneously called ‘“‘Japanners Prussian Brown,” or Japanese brown. It is soluble in linseed oil at 500° F., 170 CHEMISTRY AND TECHNOLOGY OF PAINTS and produces a film which is neither too hard nor too soft, but remarkably elastic and admirably adapted for making certain paints and varnishes. It cannot, how- ever, be said to replace any of the good linseed oil driers for mixed paints, where too flexible a paint is not desir- able, particularly on steel work or exterior work, as blisters are likely to result from the difference in expan- sion. However, as a base for the manufacture of enamel varnishes and oils this drier has proved itself admirably adapted. Linseed oil is a glyceride of several fatty acids, and Lewkowitsch has proved that water will replace the glyceride radical and hydrolize the oil. (See “New Paint Conditions Existing in the New York Subway” by Maximilian Toch, Journal of the Society of Chemical Industry, No. 10, Vol. XXIV.) The action between a fat and a caustic alkali in boil- ing solution, by which a soap is formed and glycerin set free, is too well known to need further discussion. The fatty acids which are combined with the soda can be liberated by the addition of almost any mineral acid to the soap. This saponification can be produced by the action of water alone on raw linseed oil. Where a paint contains lime or lead this hydrolysis probably is hastened. We have here an excellent explanation of the so- called porous qualities, or non-waterproof qualities, of linseed oil as a paint, which is further brought out by the fact that when linseed oil is treated with Prussian blue or Japanners brown it cannot be hydrolized by means of water, for the acid radicle has formed a com- plete compound with the iron in both of these driers, and the prolonged heating has volatilized the glycerin. Con- sequently, when a paint is made by the treatment of linseed oil at a temperature of over 500° F., with a LINSEED OIL Lat. neutral and soluble base like the ferri-ferro cyanide of iron, the resulting film is not linseed oil nor a linoleate of any base with free glycerin, but a complex compound com- posed of the various linseed oil acids united with iron. This gives us the basis of waterproof paints. This is evident from the quality of patent leather, which is not only much more flexible than any paint made in the ordinary way, but is likewise waterproof. Waterproof paints are, however, made at the present time by eliminating linseed oil and substituting China wood oil and perilla oil. _ There are questions in regard to the physical and chemical characteristics of linseed oil on which there has been considerable discussion and naturally a difference of opinion. The first is whether linseed oil dries in a porous film, and the second is whether linseed oil while drying goes through a breathing process during which it absorbs oxygen and gives off carbonic acid and water. With reference to the porosity of the dry film of linseed oil, the following extract is made from the Journal of the Society of Chemical Industry (May 31, 1905, ‘“‘New Paint Conditions Existing in the New York Subway” by Maximilian Toch). 72 CHEMISTRY AND TECHNOLOGY OF PAINTS “In a paper before the American Chemical Society on March 20, 1903, I gave it as my opinion that a dried film of linseed oil is not porous, excepting for the air bubbles which may be bedded in it, but that any dried film of linseed oil subjected to moisture forms with it a semi-solid solution, and the moisture is carried through the oil to the surface of the metal. We then have two materials which beyond a doubt have sufficient inherent defects to produce oxidation under the proper conditions, and granted that the percentage of carbon dioxid in the air of the tunnel is not beyond the normal, the fact that carbon dioxid together with moisture would cause this progressive oxidation is sufficient warrant for the discontinuance of paints that are not moisture and gas proof. Dr. Lewkowitsch demonstrated in his Canton lectures that the fats and fatty oils hydrolized with water alone, and linseed oil is hydrolized to a remarkable degree in eight hours when subjected to steam. It can, therefore, be inferred that water will act on linseed oil without the presence of an alkali, and that calcium added to water simply hastens the hydrolysis by acting as a catalyser. This, then, bears out my previous assertion that a film of linseed oil (linoxyn) and water combine to form a semi-solid solution similar in every respect to soap, and inasmuch as we have lime, lead, iron and similar bases present in many paints, it is almost beyond question that these materials aid in the saponification of oil and water.” If a drop of linseed oil is spread on a glass slide and one half of it covered with a cover glass, it will be readily seen under the microscope that the dried film is as solid as the glass itself, that there are no pores nor any semblance to a reticulated structure visible in the oil, and the author therefore makes the statement with o> No. gt. D is a glass flask of about 2 litres capacity. Through the tube A 3.4 grams of refined linseed oil, which had been heated to 400 degrees F. for one hour, were introduced and well distributed over the inner surface of the flask. Dry oxygen free from COz2 was blown through the flask, by means of tubes A and C, until the flask contained pure oxygen. ‘The tube A was then sealed, as shown in sketch, mercury brought up into the manometer by elevating B to the position shown. The flask was then filled with oxygen at atmospheric pressure and effectually sealed. As drying proceeded and oxygen was absorbed, the diminished pressure was read off on the manometer. When this became constant the funnel which was connected to A by a rubber tube was filled with filtered Barium Hydrate solution, and the point at A broken, allowing this to run into the flask without admission of air. In a few minutes Barium Carbonate was formed, showing conclusively that some COz had been generated by the oil. 173 174 CHEMISTRY AND TECHNOLOGY OF PAINTS absolute certainty that linseed oil dries with a homo- geneous film in all respects similar to a sheet of gelatin or glue. The question as to whether linseed oil goes through a breathing process, absorbing oxygen and liberating car- bon dioxid and water, is one of great importance and one which the author has worked out very carefully with positive results. In the illustration a piece of filter paper two inches in diameter was dipped in linseed oil of known purity and suspended in a flask in air absolutely free from CO, and water. Investigators have always com- plained of the inability to obtain tight joints in an experiment of this kind, and in order to be certain that there was no leakage all joints were covered with mercury after having been first shellacked. The mano- meter gave a curve which indicated the drying, a thermostat being a part of this instrument, so that absolutely uniform conditions were obtained. At the end of thirty days the drying curve was obtained, and when the baryta water was led into the bottom of the flask there was hardly a trace of turbidity to be noted. This experiment was repeated many times, always with the same result, and the amount of water or moisture obtained could not be weighed. It was therefore reason- able to conclude that the linseed oil gave off neither CO, nor water, but had absorbed oxygen. The author, however, concluded that this experiment was entirely too delicate, inasmuch as only one gram of linseed oil was absorbed by the paper. Therefore, an apparatus was devised as shown in the illustration, without joints and so absolutely air-tight that the ques- tion of leakage could not arise. The flask was filled with linseed oil and then emptied by replacing the oil by air free from water and CO,, the inside and bottom of the LINSEED OIL 175 flask being left heavily coated with linseed oil which had been previously heated to 4oo° F., for one hour. The manometer tube formed a part of this apparatus, and when the oil had dried completely (which was manifest by its wrinkled and bleached appearance and likewise by the manometer indication) a rubber tube was attached to the point E, a funnel inserted, and a filtered solution ‘of barium hydrate was allowed to run in as soon as the tip E was broken. After ninety seconds the solution of barium hydrate turned milky, showing conclusively that CO, had been generated in the drying of linseed oil. The next experiments were made quantitatively, and while the amount of moisture could not be accurately measured, the amount of carbon dioxid was in no case higher than ;) of rt per cent, whereas the absorption of oxygen was 19g percent. It must therefore be admitted that linseed oil does give off CO., but the quantity is relatively so small that it is a question whether it should be taken into account at all. It is now a known fact that carbon dioxid acts as a rust-producer on iron or steel, and if linseed oil gave off any appreciable quantities of CO, and water they would act as rust-producers in themselves rather than pro- tectors; and while it may be possible that some linseed oils give off more of these two substances than others, the amount under normal conditions cannot be very great, as these experiments show. Refined or bleached linseed oil is used to a very great extent for the manufacture of white paints. The methods employed for bleaching linseed oil have not undergone very much change until lately. The coloring matter in linseed oil is largely chlorophyll, the bleaching of linseed oil depending not on the extraction of this chlorophyll but on its change into xantophyll, which is yellow. b | No. 92. DETERMINATION OF CO, AND H2O IN DryING oF LINSEED O11 —A piece of filter paper was immersed in pure linseed oil, and, after the absorbed oil was weighed, the filter paper was suspended in the Erlenmeyer flask, on the bottom of which was a solution of Barium Hydrate (free from COz2) to absorb the CO, formed by the drying of the oil. The flask was immersed in a water- thermostat, the water of which was stirred by a revolving mechanical stirrer. A thermo-regulator, by means of which the gas-flame under the thermostat was automatically regulated, was placed under the flask. By opening the glass- cock, oxygen was admitted from time to time to the Erlenmeyer flask, and the absorption of oxygen was read on the mercury-manometer. ‘The readings were always made at the same temperature. The oxygen, before entering the Erlen- meyer flask, was passed through the KOH bulb, where it was washed free from CO:. This experiment was conducted in triplicate with great care, the joints being all sealed with shellac and placed under mercury. No CO: or H2:O beyond a trace could be determined, owing to the small quantity of linseed oil which the filter paper contained. 176 LINSEED OIL 177 Sometimes linseed oil will have a reddish cast instead of the usual greenish cast. This color is attributed to another form of organic matter known as erythrophyll. These three tints, the green, yellow, and red, are analogous to the tints in autumn leaves. All methods for extracting chlorophyll from linseed oil have proved extremely difficult and expensive. The ac- cepted method, therefore, has consisted in the treatment of linseed oil with an acid in order to convert the green coloring matter into the yellow. This is probably the reason why no linseed oil exists which is water white, although the author has made several samples which are almost color- less, but when compared in a four-ounce vial with chemi- cally pure glycerin it can readily be noted how far from colorless the so-called bleached linseed oil is. The method employed for bleaching linseed oil consists in the addition of sulphuric acid and the blowing of air into the oil at the same time. The oil becomes cloudy and develops small black clots. When this cloudiness is allowed to settle out, or the oil is filtered through a filter press, it is very much paler in color, and is then known as refined or bleached linseed oil. Sunlight has a similar effect, the oil produced by bleaching with light and age being superior in quality to the sulphuric acid oil. In the sulphuric acid treat- ment the oil, the water, and “foots,” together with an appreciable amount of emulsified oil, settle to the bottom of the tank. These are drawn off, and are of some value for making cheap barn paints by mixing with lime and the oxids of iron. In another method, which produces a still better bleached oil, chromic acid is used. If a solution of this acid, which is blood red, be added to linseed oil, and the mixture agitated, a very much paler and more brilliant oil is obtained, but it is rather 178 CHEMISTRY AND TECHNOLOGY OF PAINTS expensive to produce. The treatment by means of an electric current in the presence of moisture is likewise used to some extent, but it appears that this method is far more suited to other oils. Great secrecy is main- tained among those who have a knowledge on this subject. Peroxid of hydrogen has likewise been recom- mended, but from the standpoint of cost the sulphuric acid method is still the one that is used to the greatest extent. ; The new methods which are favorably spoken of, and which the author has found to be inexpensive and efficient, involve the use of the peroxids of calcium, magnesium, and zinc. These peroxids are made in‘o paste with water, one pound being sufficient for 200 gallons of linseed oil. This amount of oil is placed in an open kettle or vat, together with the peroxid, and thoroughly agitated. During agitation a strong solution of sulphuric acid is added, which liberates nascent oxygen. If the oil be allowed to settle, or is filtered, and is then heated to drive off any traces of moisture, a very brilliant pale oil is obtained. It has always been understood that linseed oil con- tained albuminous matter which coagulated at a tem- perature of 400° F., or over, and produced a flocculent mass. When an oil answered this reaction it was said to “break”’ at the low temperature and was useless for making varnish oil and other high grades of linseed oil. G. W. Thompson found that this break was not due to the presence of albuminous and nitrogenous matter, but that it was caused by the separation of several phosphates. This explanation has generally been ac- cepted as correct. If an oil, therefore, is allowed to age, the phosphates settle out and the oil does not break. Cold-pressed linseed oil, if it breaks at all, does not break LINSEED OIL 170 at as low a temperature as hot-pressed oil. Bleached linseed oil does not wear as well as the oil that has been clarified by standing. The demand for brilliant white paints or brilliant enamels is responsible for the manufacture of the so- called water-white oils. From a large variety of tests made by the author it was fully demonstrated that white paints composed of mixtures of pigments such as sublimed lead, zinc oxid, and white lead all showed absolutely the same whiteness within two weeks after they were exposed to the light, irrespective of the kind of raw linseed oil used. One of the five tests was made with a paint prepared with a linseed oil that had not been aged for more than two months, but within the time mentioned it was just as white as the rest. Linseed oil paints are supposed to deteriorate after a few years and lose their value, owing to the decomposi- tion of linseed oil. This statement is questionable, and while there is no doubt that the ready-mixed paint thickens and changes slightly in its chemical and physical characteristics, the change is exceedingly small in a con- tainer which is hermetically sealed. There is no doubt in regard to the reaction which takes place between the oil and white lead, zinc oxid, and a number of the unstable compounds in a mixed paint. While these reactions are very slow, they are at the same time very definite. If the value of a paint were reduced to a curve it would probably be found that the curve would be represented by the arc of a large circle approaching a straight line. As far as paste paints are concerned, particularly white lead, all painters prize white lead more highly when it is old than when it is fresh. 180 CHEMISTRY AND TECHNOLOGY OF PAINTS Typical Analysis of Bleached, Refined Linseed Oil Specific, Gravity Sai.-Al ae rcs eon ene nae .932-.934 Todine Values Hanus). 90.0. eee Above 180 Saponifica tionsValuic iam (ec sey IQO-194 AcidtY ale. ret eaeks cas yeast eee ee 355 1924 AMERICAN SOCIETY FOR TESTING MATERIALS STANDARD SPECIFICATIONS . FOR PuriITY OF Raw LINSEED OIL FROM NorRTH AMERICAN SEED Serial. Designation: D 1-15 These specifications are issued under the fixed designation D 1; the final number indicates the year of original adoption as standard, or in the case of revision, the year of last revision. ADOPTED, 1913; REVISED, 1915 I. PROPERTIES AND TESTS Ve Raw linseed oil from North American seed shall conform to the following requirements: Maximum Minimum (o) 15-5 Specific Gravity at ex Cee 0.936 GV 032 I or : 25° Specific Gravity at He Cae 0,081 0.927 2 AcidsNumbérs nay eee eee 6.00 Saponitication Number. see ss 195. 189. Unsaponifable matter, per cent... ere res Refractive:index-atay Gre ee I. 4805 1.4790 Iodine Number (Hanus)......... ae 180 IL. METHODS” OF TESTING, 2. The recommended methods of testing are as follows: General. — All tests shall be made on oil which has been filtered LINSEED OIL 181 at a temperature of between 60 and 80° F. through paper in the laboratory immediately before weighing out. The sample should be thoroughly agitated before the removal of a portion for filtration or analysis. Specific Gravity. — Use a pyknometer, accurately standardized and having a capacity of at least 25 c.c., or any other equally accurate method, making a test at 15.5° C., water being 1 at 15.5° C., ora test at 25° C., water being 1 at 25° C. Acid Number. — Expressed in milligrams of KOH per gram of oil. Follow the method described in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, page 142. Saponfication Number. — Expressed as with Acid Number. Blanks should also be run to cover effect of alkali in glass. Follow method given in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, pages 137-138. Unsaponifiable Matter. — Follow Boemer’s method taken from his Ubbelohde Handbuch Der Ole u. Fette, pages 261-262. ‘To too g. of oil in a 1000 to r500-c.c. Erlenmeyer flask add 60 c.c. of an aqueous solution of potassium hydroxide (200 g. KOH dissolved in water and made up to 300 c.c.) and 140 c.c. of g5-per cent alcohol. Connect with a reflux condenser and heat on the water bath, shaking at first until the liquid becomes clear. Then heat for one hour with occasional shaking. ‘Transfer while yet warm to a 2000-c.c. separatory funnel to which some water has been added, wash out the Erlenmeyer with water using in all 600 c.c. Cool, add 800 c.c. of ether and shake vigorously one minute. In a few minutes the ether solution separates perfectly clear. Draw off the soap and filter the ether (to remove last traces of soap) into a large Erlenmeyer and distill off the ether, adding if necessary one or two pieces of pumice stone. Shake the soap solution three times with 4oo c.c. of ether, which add to the first ether extract. To the residue left after distilling the ether add 3 c.c. of the above KOH solution, and 7 c.c. of the 95-per cent alcohol, and heat under reflux condenser for 10 minutes on the water bath. Transfer to a small separatory funnel, using 20 to 30 c.c. of water, and after cooling shake out with two portions of 100 c.c. of ether; wash the ether three times with 10 c.c. of water. After drawing off the last of the water, filter the ethereal solution so as to remove the last drops of water, distill off the ether dry residue in water oven and weigh.” 182 CHEMISTRY AND TECHNOLOGY OF PAINTS ' Or, any accurate method involving the extraction of the dried soap may be used. Refractive Index. — Use a properly standardized Abbé Refrac- tometer at 25° C., or any other equally accurate instrument. Iodine Number (Hanus). — Follow the Hanus method as described in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, page 136. 1924 AMERICAN SOCIETY FOR TESTING MATERIALS STANDARD SPECIFICATIONS FOR Purity OF BorILED LINSEED OIL FROM NortH AMERICAN SEED Sertal Designation: D 11-15 These specifications are issued under the fixed designation D 11; the final number indicates the year of original adoption as standard, or in the case of revision, the year of last revision. ADOPTED, IQI5 I. “PROPERTIES AND THs Is t. Boiled linseed oil from North American seed shall conform to the following requirements: Maximum Minimum Specific Gravity at res CR sae 0.045 = 201g37 Acid SN tim bei: oe eae ere 8. ESR aes Saponification Number.......... LOGE 189. Unsaponifiable Matter, per cent. .. 154 eee Refractive Index ate ceC es 1.484 1.479 Iodine Number (Hanus) =.= 3) eee 178. ASH Der. Cent acer wae ee penne Oy On? Manganese, per ‘centia) 0.2 0.03 Calcium, per-cent Lead, per gentax* 72 52 Map ay ee eee O.1 LINSEED OIL 183 TW. METHODS OF TESTING 2. The recommended methods of testing are as follows: General. —The sample should be thoroughly agitated before _ the removal of a portion for analysis. Specific Gravity. — Use a pyknometer, accurately standardized and having a capacity of at least 25 c.c., or any other equally accurate method, making a test at 15.5° C., water being 1 at ras ouga On Acid Number. — Expressed in milligrams of KOH per gram of oil. Follow the method described in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, page 142. Saponification Number. — Expressed as with Acid Number. Blanks should also be run to cover effect of alkali in glass. Follow method given in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, pages 137-138. Unsaponifiable Matter. — Follow Boemer’s method taken from his Ubbelohde Handbuch Der Ole u. Fette, pages 261-262. “To 100 g. of oil in a 1000 to 1500-c.c. Erlenmeyer flask add 60 c.c. of an aqueous solution of potassium hydroxide (200 g. KOH dissolved in water and made up to 300 c.c.) and 140 c.c. of 95-per cent alcohol. Connect with a reflux condenser and heat on the water bath, shaking at first until the liquid becomes clear. Then heat for one hour with occasional shaking. Transfer while yet warm to a 2000-c.c. separatory funnel to which some water has been added, wash out the Erlenmeyer with water using in all 600 c.c. Cool, add 800 c.c. of ether and shake vigorously one minute. In a few minutes the ether solution separates perfectly clear. Draw off the soap and filter the ether (to remove last traces of soap) into a large Erlenmeyer and distill off the ether adding if necessary one or two pieces of pumice stone. Shake the soap solution three times with 4oo c.c. of ether, which add to the first ether extract. To the residue left after distilling the ether add 3 c.c. of the above KOH solution, and 7 c.c. of the 95-per-cent alcohol, and heat under reflux condenser for 10 minutes on the water bath. Transfer to a small separatory funnel, using 20 to 30 c.c. of water, and after cooling shake out with two portions of 100 c.c. of ether; wash the ether three times with 10 c.c. of water. After drawing off the last of the water, filter the ethereal solution so as to remove the last drops of water, distill off the ether, dry residue in water oven and weigh.” 184 CHEMISTRY AND TECHNOLOGY OF PAINTS Or, any accurate method involving the extraction of the dried soap may be used. Refractive Index. — Use a properly standardized Abbé Refrac- tometer at 25° C., or any other equally accurate instrument. Todine Number (Hanus). — Follow the Hanus method as de- scribed in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau of Chemistry, page 1306. Ash. — The determination of the percentage of ash and the constituents thereof may be made by any method which gives accu- rate results. STAND OIL Stand oil is a very heavy, viscous form of linseed oil which has great use in the arts for the manufacture of both air drying and baking enamels. It is supposed that it originated in Holland, but there is a difference of opinion on this for the reason that the table oilcloth manufacturers in Scotland made a similar oil under the name of “marble oil” long before the Dutch made any enamel paints. The method of making marble oil, which is a form of stand oil, is simply to heat a linseed oil which has no “break”! to 550° F., and to keep it at that tem- perature or slightly over until it becomes very heavy and viscous. Its specific gravity changes from .g30 to .g80, at which point a small quantity placed on a piece of glass and allowed to cool piles or stands up in a little mound and runs very slowly. With the oil still at 550° F., a small quantity of litharge is added; this is known as adding the drier on the downward cool, which simply 1 An oil from which no black flocculent particles separate at 500° F. is technically known as an oil which has no “break” or does not “break.” LINSEED OIL 185 means that the oil takes up the drier not as the heat is increasing but as the heat is decreasing. The amount of litharge added is necessarily very small, because if more than one tenth of 1 per cent be added the oil becomes considerably darkened, while the object in making an enamel oil or marble oil is to retain its color. Oil made solely with litharge as a drier dries very tacky and must be baked to at least 110° F. for several hours before it will dry entirely. For this reason many add a small percentage of borate of manganese with the lith- arge, or chloride and sulphate of manganese, as a drier. Of all the driers for making stand oil for enamel paints cobalt is the best, for a very small quantity is necessary to perform the function of drying and no bad results are obtained. Where manganese driers are used and continued oxidation takes place a white enamel paint may turn entirely pink, due to the formation of a manganese salt of that color. Where lead is used slow and sticky drying may result, but where lead and manganese are used together in dark colored enamels excellent results are obtained and any change in color value is not noticed. Some stand oils are made also by partial oxidation or blowing and partial heating. ‘These, however, are short, and when placed between the thumb and forefinger and rubbed rapidly do not form a long thread but a short thread. Experience has taught that a short oil is short lived and a long oil is long lived. There is obviously a good reason for this, as the short oil has been highly oxidized and continues to oxidize after it is dry. Yet for interior enamel purposes a short enamel oil will last many years. One of the best features of enamel oil or stand oil is that brush marks even with a poor brush are eliminated 186 CHEMISTRY AND TECHNOLOGY OF PAINTS and flow together. Zinc oxid is the principal pigment used in the manufacture of all of these enamel paints. JAPANNER’S BROWN OIL This is a stand oil or marble oil identical in all respects with that described under the heading “Stand Oil,” excepting that it is dark in color and therefore only used for making dark colored enamels such as patent leather, machinery enamels and waterproof coat- ings which must have a high glaze. The method used for making this oil depends very largely upon the good quality of the linseed oil, and the oil must have no tendency to “break”? whatever. It must be heated to 550°, at which temperature Japan- ner’s Brown is added slowly in the proportion of three ounces to the gallon until the oil, which at first is muddy, becomes clear and of the color and consistency of dark honey. As the present tendency is to varnish or enamel auto- mobile parts and bake them at fairly high temperatures this oil has become of great value, particularly when mixed with a fossil resin varnish, and as there are but very few automobiles which are painted white the dark color of this particular oil is no objection. For the manufacture of an enamel paint for painting engines which are continually at a temperature of be- tween 170° and 212° F. on account of being water jacketed, it has been found that the dark enamels used for this purpose when made with the Japanner’s Brown oil con- taining at least 25 per cent of a high grade fossil resin varnish give results that are astonishing. Enamel paints on an engine, composed of the materials just described, will at the end of a year be practically as good as the day that they were applied. LINSEED OIL 187 MANUFACTURE OF STAND OIL AND BOILED OIL The tendency even at this writing is to manufacture both stand oil and boiled oil by rule of thumb. A certain kind of oil is put into a kettle, it is heated to a given temperature and drier added either before or after it thickens, and when the workman decides that the bead will pile, or that the string between the finger and the thumb is long enough, or that a cooled drop on glass is elastic, it is considered finished. This is not by any means the manner in which heavy bodied oils should be made, and there is no necessity for using rule of thumb methods. In the first place, the oil selected must be a non-break oil. In the second place, from previous experience it must be known how many hours to heat an oil slowly until it reaches the polymerization or thickening period. From time to time sufficient oil must be taken out and put in a cylinder, and the cylinder placed in cold water so that the temperature of testing is not over 70°. The specific gravity of the oil is taken, and if the standard sample of enamel oil should be .970, at which it will produce its best results, each subsequent batch should be heated until it has obtained that specific gravity. There are, of course, many methods by which these heavy bodied oils are made. Some are produced by means of boiling and blowing, and some by boiling alone, and some by blowing alone. ‘Those that are produced by the heat method which is popularly called boiling — but the oil never comes to a boil — give the best results because the acid number is lower and it does not continue to oxi- dize as quickly as blown oil always does. Where color counts only nascent cobalt drier should be used. Where color does not count, as for dark products, it is advisable to use mixtures of lead and manganese. 188 CHEMISTRY AND TECHNOLOGY OF PAINTS Enamel oil must be kept light and many varnish makers use manganese borate as a drier. This alone is one of the poorest and most inefficient of driers, but when 4 of 1 per cent of cobalt soap is added to it there is hardly any per- ceptible difference in the color, and the oil will dry rapidly. A well made standardized stand oil will not liver or saponify with any pigment, and, when reduced with sufficient thin- ner, will flow out and obliterate brush marks. Some enamel makers add from 5 to to per cent (by weight) of No. 1 Singapore Damar. Where this is done it must be added to the oil while cooking, otherwise the resulting enamel will bloom. Typical Analysis of Heavy Bodied Blown Oil Specific:Gravity;.....- 62k er .988—.993 Saponification, Vdlite. Gay ee 0.02039 Heat Test (Browne's), eae ee Tox min. Whenever crude China wood oil is treated with barium peroxide, the oil is bleached; but it does not remain clear on standing. This is probably due to formation of an insoluble barium compound, resulting from the chemical reaction between barium peroxide and the oil. Flashing is liable to take place when barium peroxide, without the addition of water, is heated up with the oil. CHINA WOOD OIL 201 This can be avoided by first bringing the oil up to a high temperature, and then dropping in the barium peroxide. (b) The oil was treated with 2.5 per cent of an activated carbon. The mixture was heated up to 105° C. and stirred for half an hour. After filtration, the oil was clear and bleached to a certain extent. The constants of this oil were: PectimemaravirvedG0 I.) icp. Range ts: 0.9405 io mrocuve Index-(2t.5° Cock ee ee. Pasl7S Pispemion. Value (eres Co) oe we. 0.02048 Freatelesty Browne Sles. hee sh. ee tacts va 10s min. A peculiar chemical action was observed,— that the oil which was treated with an activated carbon began to crystallize in four or five days and finally turned entirely into a solid white mass. The acid numbers of this oil and of the original oil are practically the same, being 8.6 and 8.75 respectively. The melting point of the solidified tung oil is between 51° and 53° C. This solid form is probably the glyceride of B-Elaeostearic acid, formed by a molecular rearrangement of the liquid form and which is catalized by activated carbon. It was first noticed by Cloez that light has the same effect of changing liquid tung oil into the solid form. (c) The crude oil was simply heated up to 200° C. and the temperature maintained for ten minutes and finally filtered. The oil obtained has the following constants: BHCOMGKGITAVILY (OO -sHL) ates «ct qi 0.9420 Refractive Index (21;75°°C.))o-.... fein toner TesSryo Dispersion. Value (ar. 57 Gj oer oe as ©.02000 Hieat. best CBrowne’S)s..cnts . oats et ae Seo 10x min. (d) The crude oil was mixed with 5 per cent of Fuller’s earth and heated to 150° C. for fifteen minutes with constant stirring. After filtration, a very light colored clear oil was 202 CHEMISTRY AND TECHNOLOGY OF PAINTS obtained. The oil also remains in good condition on stand- ing. Its constants may be shown in the following table: Specific (Gravity (60 ti2)..2a re eee O.9401 Refractive Index (or S¢C: 02 eee 1PSL76 Dispersion Value~2%-54G@.). o) ep ee 0.02053 Heat Testi( Browne's) 2)... a: eee 105 min. (e) For thirty minutes the crude oil was heated up to 120° C. with 1 per cent bone black. Then it was filtered. The oil was clear and bleached to some extent. It had the following constants: Specific: Gravity (Go 4b) A272. eee ©.9397 Refractive Index @1.5 C42) ae 1.5176 Dispersion Value. (21.5° Cj ya eee 0.02043 Heat Test: (Browne's). 2/253. ee roy min. (f) The crude oil was treated with 2 per cent of Fuller’s earth and 2 per cent of bone black. The mixture was heated up to 120° C. for thirty minutes and then filtered. The oil obtained was very pale in color and clear. It had the following constants: Specific'Gravity (60°. Hat, ae ee 0.9395 Refractive Index (21.5> C:) fa. ee iE Gis Dispersion Value (1.5 CG.) ae 0.02042 Heat Test: (Browne’s) (:. Resco ee 103 min. Many other methods have also been tried in the laboratory such as the use of the oxygen liberated from manganese dioxide, potassium bichromate, and sodium peroxide. Bleaching with sulphur dioxid and chlorine gas did not give any striking effect. Among all the methods tried bleaching with 5 per cent Fuller’s earth, or with a combi- nation of Fuller’s earth and bone black, gave the best result. CHINA WOOD OIL 203 EXAMINATION OF CHINESE Woop OIL Two samples of Chinese wood oil were used (one from J.M.C. and the other from M.A.F. Co.). Each of these was adulterated with 5 per cent, to per cent, and 15 per cent by weight of the following oils, — paraffin oil, soya bean oil, linseed oil, perilla oil, corn oil, menhaden oil, stillingia oil, peanut oil, tea seed oil, tallow seed oil, cotton seed oil and rape seed oil. The specific gravities of the oils were determined by the use of a Westphal balance at 60° F. A Zeiss Abbé’s refractometer was employed for the measurement of the refractive indices, while the dispersion values were calculated from the refractive indices and the readings indicated on the drum of the compensative prisms with the aid of the dispersion table provided for the re- fractometer. The temperature throughout the experiment was maintained at 21.5°C. The following table shows the results obtained for all the original oils used in the adulteration of the two samples of Chinese wood oil: Oil SP. Gr. Ref. Ind. Dispersion 60° F. Pai des OF PAN sed Oe Chinese wood oil J.M.C....... 0.938 I. 5181 0.02073 Chinese wood oil M.A.F. Co... 0.939 Doers? 0.02074 Meat Data. Olle. oa. tk 0.874 1.4870 O.O01158 Bove Dea allie)... oe. ola 0.944 1.4769 0.01027 Refined linseed oil............ 0.933 1.4796 0.01078 SEES CH, Soy) eS re ©.940 LeAy53 0.01008 Eee PiiceOliar ney sce 0.934 1.4821 ©.01062 08, HAT 0 Oe a ee 0.936 1.4822 O.OIII4 Be Olas oa oe ie ea «hs 0.033 Lot 713 0.00971 SLEW EEO TS Bo) ROS ee tee 0.939 1.4816 0.01036 eepSeeCh Ol 8. a bale he cchon omen) 1.4605 0.00927 MeO WSCCUAOI sy.) 15. os eek 0.949 1.4860 ©.01092 Pottonssced? Oiled 7s fete 0.922 I.4720 0.009897 fee SCE Ol 4a eee. On ge ©.914 1.4734 0.009894 204 CHEMISTRY AND TECHNOLOGY OF PAINTS The following table shows the effect of adulteration on the physical constants of Chinese wood oil: SAMPLE I. J.M.C. CHINESE Woop OIL Oil Chinese wood oil alone. ..... 7... ar's.le Ke. ene oy ) We ooh eb: eee ce Pan C. W.O. plus 5% paraffin oil... Cow. Oe 4204, a eae CoWLOee me, 2 et COW ON e557 cova pean on ClW Ons 0 ‘<“ ‘< Gs W.O cc 15% ce (a9 (79 C W..O.8 ts eo, linseedsoileae Ge WO. eet eae a ee Se CWO. “Ree. C.W.0. “ 5% perilla oil... CIW= OF eR o ere ge ee CCH ee ee Gi Ws OF me is econ. onl eee CW Osaercee ae CAVEO tC C. W..0. 18% menhadensoile.. CEWe Ome eetou. oy s CW. Ov eS eon eee GawsOme Eo siillingiasou sae CP We OF rs 7 +. is CMON Ne eh C. W. OF #2945) Deaniit oleae CaWEe OF erero 0 vias a eat ey CWiO; it tee eee ce) Oo Oo Ref. Ind. Dispersion pay ae 2 8 ates LT. 5ISTo. Sos02074 La! 5105. -onozorg 1.5149 0.01964 J5132 eCmoloas e 1.5160 0.02007 1.5130 >) OfOlane I.5IIQ 0.01920 1, 5162)>\ oC. O2e07 ¥.5143-) UOno1070 L S22 20; 0toe. 1.5103) 10702026 Te5IA5 2 OnCLg LUST 25 Np Ono nose 1..5150% » 0.02007 1.5140) 0 s01077 I SILO sO volpay LU5102 4, 0°62628 1.5130) 0.01077 I.5115 0.01903 1.5163) O102020 1.5146 0.01990 1. S12% a (0, 0104e eI . 5158) -0,,02007 512008 OcObGas .5LI4* 0. OT@00 eS & CHINA WOOD OIL 205 The effect of adulteration on the physical constants of J.M.C. China wood oil is shown in the following table: Ref. Ind. Dispersion Kae te . sp. Gr. one GO eter ars peers ean) epiise 57, tea seed oll:.>. 2. ; ORO 3o mers SG OTe a ee en 01920. 6 1.5135 Se OT Oe Of095*a Tas 10 C.W.O. “ 5% tallow seed oil (Han- Ky Pemie g fe) faekt OCO41Ts S107 C.W.O. “ 10% tallow seed oil (Han- Kove ierpac fe ya O08) gems SA C.W.O. “ 15% tallow seed oil (Han- HOW age ho On045Uh T5135 Gave w. e854, cottonseed oil... . - OnGey aut oS TOL eWEOaje elon ee eked seat eis Oh Gk ys @ ay idmcwices CAV Ore oT 5G PeRiee ieee Or Gey ete SLT 4 ee Orme ees, rapeseed Oils. 2... 0;038>- 1.5161 RN ee oe. 0.930). Te 5129 eG tee ae? 0.035 1. 5116 ay ee 8 Sova. bean Gil ($2). 20.938* ~ 1, 5162 Pay eOesetOl; eh ee OO gS er elerelA © a a te Th aay eee heat OF O08 Tp ys LLG omy On 5% menhaden oil (52)...0.938 1.5166 Cee Oe 10% aT ke OO sO teh oT AY We Ot 5% é ET EAS EMO 0g comp aweeks) SAMPLE II. M.A.F. Co. CHINESE Woop OIL Chinese wooo alone. oa os a SRG TSE aoe pus. 35%, pataiin-ol. 3... G7025 an I S105 Pe LO Ay 220s De eee OL0Son) Tasia5 Ce wWeeO.aee F159 .9 -o ES od on Sp 7 Sie le Sse awa sano osoya bean oily x62, G2O30e sea S101 Mea) toes ls Te eee 02920 a1 e5140 (Cn, NON G RaSh ate oe ee ee eS O 040 nk 122 OF OF Of Ono oO O Oo O 02006 01970 01879 ,02013 .01978 01949 .02005 .O1962 .O1916 02026 .O1982 .O1925 .02005 .O1979 .O1940 .02029 .01978 .O1922 .02074 .02046 .©2000 .01967 .02030 .O199O -O1954 206 the physical constants of M.A.F. Co. China E: O ECE SEES. CRACOW PhOnOw ie he MeV Koh ora Ce ee C okene W. Shee ges eine ce O. ws O. O O O O O. O. O O O O O O O O O. CHEMISTRY AND TECHNOLOGY OF PAINTS Oil bous plus ts, linseed oil ye, soe e020 ONT OV bales, baie one ne CRO Eh TSO Oh eee ee oO ee ‘eho petitla oil uta b aeeeee 0.938 OS TO Gig ks amet ea eer 0.938 as 15% P Pim Scans ie eee 0.937 vi-c| OE COR Olle. miter ee 0.939 f IO Soy SSE eee ee 0.939 ROT AM Ese 0.939 “5% menhaden oil, 9.6 0.939 SEONG Me oe Face 0.939 6 Lee ee aE IK ot 0.939 “35% stillingia, Oil come Os a3 OU CS ee eae 6c 15% es pe earth. oF 0.937 "2 LeU WeaNut Olle bake eames 0.939 ToS, ae te tear a eae 0.939 Laas; aaa oe Sp- Gri Ref. Ind. Dispersion Oy We Br MSO Nan | 1, 5102 “Ov02032 IL. 5141 ~ 0.02004 I... 5124 4, RO, OLO50 1.5166 0.02044 1.5148 0.02004 I'5130) Of07032 Li 514 fio Osc rege 1.5120" -Glorgss I. S100 .%sO.c2o42 1.5148 0.01990 L-. 5130) OL OLQRS I.5160 0.02019 1.5138 0.01990 1.5112 “4001070 The following table shows the effect of adulteration on O. 0: O. O. plus onene ¢ 5G. leauseedr Ol ay ee ae 0.037 LOVE" ee Seen ens 0.936 15% 2 ee ee 0.935 5% tallow seed oil (Han- MEOW i cana! eae re 0.940 10% tallow seed oil (Han- kow) e300 a ee 0.942 15% tallow seed oil (Han- kow) Geer eee 0.944 5%, cotton secd.ollwwaat 0.938 LOC Gm be ache e cave Ce 0.937 ey a Wes 0.936 Ty iE lie Lea} = ee wood oil: 5160” 0, 02017 .§139-- OnGrogs 5112 0.01899 5106 ~ 10, 02012 »SIhO PO, 01970 .5140 0.01945 5162036, 02020 .5140 0.01990 , 5119s Beroross CHINA WOOD OIL 207 Sp. Gr. Ref. Ind. Dispersion Oil 60° F. 21-5. i thee veep iis= 5 rape seed oil....,.. 0.939) 1.5164 © 0.02015 ere eo tOY,- | een a 01037 eae Te TAC/E O.01000 Re eS a. 0.035 TeS121- 0.01026 Seve = 5%, soya bean oil (S2).. 0.939- 1.5166 0.02628 ever. as TOU,“ eee oerrerOrG ton r Te S144. 1 0.01000 CeWeOs 15% * aE! ee OS 4 Smeal 61234. OF O10 21 eee eo, tnenhaden oil (S2):. 0.9030' 1.5168 ~ 0.02033 net, 10% ‘f On Aco mr S152. 0.01084 ays ers, . eee meen O.O30) Mt 01228 OL OTO2T HEAT TEST OF CHINESE Woop OIL Apparatus. — Test tubes, 15 cm. by 16 mm., closed by a cork so perforated that a giass rod could move freely. A 4o0o-c.c. glass beaker, 10.5 cm. by 7.3 cm., filled with soya bean oil to a height of 7.5 cm. A nitrogen-filled thermometer of 600° F., placed at 1.5 cm. from the botton of the bath. Procedure. — The bath was heated to 560° F. Then the test tube containing 5 c.c. of the oil to be tested was im- mersed so that the bottom of the tube was level with the lowest part of the bulb of the thermometer. The time was noted. The source of heat was so adjusted that the tempera- ture of the bath was kept as steady as possible at 540° F. When the sample had been in the bath 9 minutes, the glass rod was raised at intervals of + minute until the sample became gelatinized. The time was again recorded. The results obtained from the experiment are shown in the following tables: — TaBLE I. J.M.C. CuInEsE Woop OIL Time in Minutes Oil Run 1 Run 2 Average Ciinese wood oll alone, ... ...hs..0n. ig ete! THA20 Liye ey er piis 5%, paratin: ollie... 12 380 1 ae ae) Le eV Oma 8TOUG.. rs bees by cr F23250 120-20 T2040 og ie ORR S25 5 oy Aaa Soa naana st his ae [5700 fists oo. 208 O. O O O O O O O O O. O. O O O O O O O O O O Nel pr. groove. ep euololmc chen tougtoaoiel oe Sam re re ge ee Oil CHEMISTRY AND TECHNOLOGY OF PAINTS Time in Minutes Run 1 Run 2 Average plus 5% soya bean oil..... nea T2220 logge pe FO ae ee plea one a 13.7 20 T9hLO L321 Se Eee Oe eee 14:50 14/230 14 : 40 ‘ite 5 U7: INSEE Ola ee 12:15 12745 2s ETO Ug Musa we! ot 14°230 14°20 TA 48 eo Cs Sie Nast Bereta 16:00 T5240 DS 50 useo perilla. oll een L210 L2ae50 12:40 Ty LOWE i cease See ee ae Nee ee Tatas T2eaS RON te eR I cc ve) ohn 15.210" 2 acy O Eo 20 Hy iS Ce eCOT TCO Loa a eran Leto 13:40 [3;. 30 OT TOU al ee ee ee TAs Iqi2s 14.728 TS One one ee ee 16:20 16:10 TOgae oe 505 menhaden-onl sae Toes 124520 13-218 LOU os Chsscees Rew ee. 14.210 1Al Od aR, - : 14 : 40 14 50 14:45 ‘-'s@, stillingia oul ge = ta seco P2520 12 Os ior, es Mea ac ORIG i3°s0c 12:50 tke a7, be i ie bse 13:40 nee 5 7G. DEAT Oh einc te ices I2 :00 Tiea5o Tiss CN TOGG aS ac ean atee eee E320330 E3026 Lass oT 5 Oe hn sh eed ee eee 14.345 142350 14:48 HEAT TEST OF CHINESE Woop OIL Chinese wood oil alone Gwe Ocplus GaWw20ss- Oil 5% tea seed oil 10% c¢ (7 ¢ re 15% 5% tallow seed oil TOU, 66 (95 66 157% a3 (<3 66 c See sae Time in Minutes Run 1 Run 2 Average IO : 10 TOR2O Io -15 Il } 40's 21 ce eee 120 D2 FO P25 [10:14 eC ei taeat a Se Ke, LT. 2200s Lise a Lisesc Li 407 fees I2 :00 12555 12.53 CHINA WOOD OIL 209 Oil Time in Minutes Run 1 Run 2 Average 2): fas 5% Sh g08 SCOGLOlLer a. EOuceys al tes II :00 10% be Ea ye Tes OO Maio elo Tao c met Svgo. ROR? ip col oS Tere sR lien RC ARES &) Maes Golapersced Oll. .;. ae Tly) 00s 1L 00% 11:00 ero i rete he TeV EO) A220. WT Vhs oe a eee TAL, OOM so T3650) a 1315.25 By poova pean Ol (52). wietis; TO» 10°)55° > Tr 33 ee TOC 2 ee eT 2 LG eet ks es Toe TS TE pier eet To SO Perse 4O B13 kAS See 8 17, Hee oy albedo aye boa ks etetta me me Beats Li9:,00 errto Pe are hors) art Chas TEAR Beets Uy, 2 ie eer AO To. Oat oe 4c eiedel deleWe: Sevouei Nero Sae 882 2225 228 Siler mre. che: Letiede aay oe TABLE II. M.A.F.Co. CHINESE Woop OIL Oil Time in Minutes Run 1 Run 2 Average Chinese wood oil alone............... TOr30 TOr40 EOune § ewe). Dus 5% paraffin oil.. Fatt410 Leese 20 T2930 CaWe @. LOS ioe re rhcasiece A WBS Xe) vik iis seb ee Cie Ore) 51S) Bee hee Set IO I5 :20 ThetoG Pave oes, soya beanioll:. PTs 320 TT 210 a ats ers LOU peta Mile ake Cath 1 2eaES 122200 romeo eNO a tS 9, eA, ede ras Pee AO P2540 Loman eens oes 7, linseed: Ola. . os TP Gro Tease S (isi CN OO e979 Sate a 2d oh, py 2. 2 220 1p Bis [26.20 PR Ome GOL, 2S Sie a 1255.50 T8240 T2015 eave ee ene Or Herilla Ol tess oo TIa820 ieas4 i143 27 NUON) Mater eT OO), (2 wie So Wr Seats cs a Ton0 Cats eats er) ties eo Cig gas tle is 2 EE ECTS Tazo. ebook ee MeV oO) tye os 7, COT Cll er Sen cee a Tie 30 ise is rim 30 eye Otek NTO tet lant ger T2400 Toe30 Fon20 PONV AC ees Teo ilies eee ek eee ee fe Means, ict ZO Chinese wood oil alone Chae e eho onene paves eopes roles Foes Ue eigen euetels. Cini ol enone = Guone Seeing oes Fe ee ee lee re a O. pl SIMO CO OOO OrS Oma Otol CHEMISTRY AND TECHNOLOGY OF PAINTS TABLE II. ‘ us ‘ Oil .O. plus 5% menhaden oil..... O; oe 107% “ Gh eae Fe rais oe de LN exes QO. 320 69, stillnigias one O ESa 109 nee Seem COE Shea AD ay Sata OS) 5%, peanitt Oller ee, Ono! 10% ae ee eee Ops SanS Oe ae eee Oil 5% tea seed oil 109 eh se 15% c¢ 4 bg ARON 2) 5% tallow seed oil .... 10% a3 iz ee 15% (9 a9 ¢ 5% cotton seed oil ©, Se! "6, le: To wees 0b te) 2 On Re Run 1 Ile 50 12720 13/230 Tienes 12:00 ibe tae: 12 :00 13:00 14:10 ree 10% c¢ c¢ c¢ 15% (73 (a3 66 5% Tapersecd oll oye nuns 10% a3 (73 (<3 15% cc ce ce 576 10% 15% 66 6 (a3 6c 570 1o07 (5 Co 2S 6¢ 6c “ 157% “ ce 6 6¢ soya bean oil (S2) ... menhaden oil (S2) ... Time in Minutes Run 2 Average Tf 5145 Li fAy 123320 12.2725 eer ke) benzo Eis II =\10 FO Taree Lasgo Porro tenn Taye 13-510 Heras LAS co 20 147 M.A.F. Co. CHINESE Woop OIL Time in Minutes Run 1 Run 2 Average QO 2 50..a1Or ca O-L SS Il $30 “Milgs2Ge eee LI 2 §0 S12 ees 13 3 30 8 13) Soe eee TI) EO 4 Pires Bo Il 320: Sif 25 eer Il 335 9) Ae Ao eee 10 715 10125 eeowees Il 15 ° tg O yee 13 {10° [2 gle) eee 10 3 35° TOu eh eae hee eee li 55 eee 126.00 13° 30° See eee IO: 40 #2 1Os 50m a erGuee: I yy sereje eo? 1 20°: TOs Oseeet ae 10:45 10); 30euetopeto [I 130° +40) 940 ee 12 3°30 ~°12 Doh ere CHINA WOOD OIL PTT HEAT AND QUALITY TEST OF CHINESE Woop OIL By R. S. Worstall’s Method One hundred grams of the oil was placed in a porcelain casserole, having a capacity of two hundred and ten cubic centimeters and an average diameter of three inches. This was set on a wide-flanged tripod which had an opening approximately the size of the casserole. The oil was at first heated rapidly with a full Bunsen flame and stirred with a thermometer of one-inch immersion. When the temperature reached 540° F., the flame was turned down and the temperature maintained as near 540° F. as possible, until on lifting the thermometer the oil dropped with a pronounced string. The time required after reaching 540° F. until stringing, was recorded as the time of the heat test. For pure tung oil the time limit is approximately eight minutes. As soon as the oil dropped with a pronounced string, the flame was removed and the oil stirred with a stiff spatula until it became solid. After one minute the jelly was turned out and cut with a dry, clean spatula for the quality test. Pure tung oil should give a dry non-sticky jelly which can be cut like bread and crumbled under the applied pressure of the spatula. The following data are results obtained from experi- ments performed according to the above procedure. — Taste I. J°-M.C. Carma Woop Or, Oil Time of Heat a Test in Minutes Quality J.M.C. China wood oil alone aE aRO Dry,non-adherent, cut welland crumbled well. C. W. O. plus 5% paraffin oil 8 : 40 Dry non-adherent, cut wellandcrumbled well. 212 O° Se ee Oe at ae CHEMISTRY AND TECHNOLOGY OF PAINTS QO; 66 Oil Time of Heat Test in Minutes .O. plus 10% paraffin oil TSG (¢ a3 5% soya bean oil 10% c¢ ¢é (a3 ce ce a3 15% 5% linseed oil 14 iz ce 15% ¢ ce 5% perilla oil 10% (<3 (73 15% ‘< 73 5% corn oil 10% ¢ 66 15% ¢ 6¢ 5% menhaden oil 9 IO IO IO II Io: iIK®) 5 Wal 35 730 : 50 : 40 : 40 mp > OO Xs. : OO Toh 5 AS Quality Slightly softand sticky, cut and _ crumbled fairly well. Soft and sticky, cut poorly and non-crum- mable. Dry,non-adherent, cut welland crumbled well. Slightly softandsticky, cutand crumbled fairly well. Soft and sticky, non- crummable,cut poorly. Slightly softandsticky, cutandcrumbled fairly well. Soft and sticky, cut and crumbled poorly. Soft and sticky, non- crummable,cut poorly. Slightly softandsticky, cutandcrumbled fairly well, Slightly softandsticky, cut and crumbled poorly. Soft and sticky, non- crummable, cut poorly. Slightly sticky, cutand crumbled fairly well. Sticky, cut and crum- bled poorly. Soft, sticky, cut poorly, non-crummable. Dry, non-sticky, cut and crumbled fairly well. CHINA WOOD OIL BC ele er Z Ww, 258 Oil Time of Heat Test in Minutes Quality .O. plus 10% paraffin oil On25es Dame ass 595° *men- haden oil. Oar = 15% ae eek TO.4tO — Soit, sticky and non- crummable. Ogee) 59, Stillingia oil 8:35 Dry, non-sticky, cut and crumbled well. re TO, oi fi g:10 Slightlysticky, cutand crumbled fairly well. eee 5 87, e ‘3 TOS mmole sticky «cut. and crumbled poorly. Gee 7, peanut oil g:00 Slightlysoftandsticky, cut and crumbled fairly well. Ces a TOU. a 9:20. 4 Sottsand = OO 232 215 Io - LO a1s 45 20 *55 Dry, non-sticky, cut and crumbled well. Slightly sticky and soft and crumbled fairly well. Soft and sticky, cut poorly, non-crumma- bie. Slightlysoftandsticky, cutandcrumbled fairly well. Same as 5% stillingia oil. Soft and sticky, cut poorly, non-crumma- ble. Dry,non-adherent, cut and crumbled well. Very slightly soft and sticky, cut and crum- bled fairly well. Soft and sticky, cut poorly and non-crum- mable. Slightlysoftand sticky, cutandcrumbled fairly well. Soft and sticky, cut and crumbled poorly. Same as 10% tea seed oil. Dry,non-adherent, cut and crumbled well. Slightlysoftandsticky, cutand crumbled fairly well. .O. plus 15% tallow seed oil CHINAS WOOD -01L Oil 5% cotton seed oil 10% a9 6c 6c 6c 6c ¢¢ 15% 5% rape seed oil 10% 6¢ “ 6c ‘6 ‘< We 157% 5% soya bean oil (S2)? 10% soya bean oil (S2) 15% soya bean oil (S2) 5% menhaden oil (S2) 10% menhaden oil (S2) 15 menhaden oil (S2) 1 (S2) 2nd sample. 217 Time of Heat Test in Minutes 9:34 9 Io Il IO I2 IO 15) LOS, apes 45 :48 35 = 30 ges oH ols ; OO OO IO Quality Soft and sticky, cut poorly and non-crum- mable. Very slightly soft and sticky, cut and crum- bled fairly well. Same as 5% cotton seed oil. Soft and sticky, cut poorly, non-crumma- ble. Slightly softandsticky, cutandcrumbled fairly well. Slightly softandsticky, cut and _ crumbled poorly. Soft and sticky, cut poorly and non-crum- mable. Dryandnon-adherent, cut and crumbled well. Very slightly soft and sticky, cut and crum- bled fairly well. Soft and sticky, cut poorly and non-crum- mable. Slightly softandsticky, cutand crumbled fairly well. Same as 5% men- haden oil. Soft and sticky, cut and crumbled poorly. 218 CHEMISTRY AND TECHNOLOGY OF PAINTS THE PRODUCTION OF TUNG OIL IN AMERICA It will be seen from the foregoing that the archaic method of collecting the seeds from trees that receive no cultivation or attention whatever produces variable oil, and that for the further reason that the nuts are allowed to rot and split, and then heated without any care as to uniform temperature. Many of our scientific No. 98. Tune Or Nuts, grown in Gainesville, Fla. These cultivated nuts are about twice the size of the Chinese uncultivated nuts. statements are not to be relied on excepting or eta. particular sample examined, owing to the conditions of manufacture. For fifteen years experiments have been made in an attempt to grow the tung oil tree in the United States, and to find a suitable climate for its propagation. ‘There is no doubt that below Jacksonville in Florida any species of wood oil tree will prosper. There is no question that by obtaining seeds that grow in Hupeh and Szechuan Provinces which are 30° North, trees can be grown which will prosper in Tennessee, Georgia and the Carolinas, but for the present, Florida will give us a large quantity of oil, and a private corporation (Benjamin Moore & Co.) is planting between 2500 and 3000 acres adjacent to the plantations of the American Wood Oil Corporation. 210 OOD OL Yr a CHINA VAINOT J ‘SONTIGHAS ONIINVIG ‘OOI ‘ON VaINOTy ‘ATX, GIO AUVAA ANO *66 “oN 220 CHFMISTRY AND TECHNOLOGY OF PAINTS It is very interesting to us that the oil produced from the seeds in Florida have different characteristics from the Chinese oil, but this is to be expected by anyone familiar with the transplanting of indigenous plants. Tung oil produced in Florida in 1924 has the following characteristics and constants: PERCENTAGES OF Ort IN MEAT! (BY EXTRACTION) 64 PER CENT CHARACTER OF OIL PRESSED FROM MEATS Color: very pale — almost water white. Specitic: pra vity a5 35) faa ee ee 0.941 Acid value:in aleohal-benzoly ae 5 eer 0.0 saponification Valueen 1 eet nase eee 194.3 Todine value (half-hour, Wijs)............ 166.6 Refractive index. at 35 C3 ee a ee Li5i93 Browne heat test (A.S.T.M.) — minutes... 9% Fruits from S. Tarnok (Augusta, Ga.) CHARACTER OF OIL PRESSED FROM MEATS Color: very pale — almost water white. Specific gravity-at 15.5 Gate, peeesereee °.940 Acid value in alcohol-benzol.............. 0.0 Saponification=valueys7 2 sua eee 195.0 Iodine value (half-hour, Wijs)............ 165.6 Refractiveindex a25 (Ce ae re eee 1.5188 Browne heat test (A.S.T.M.) — minutes... 93 SAMPLE OF AMERICAN TuNG OIL? General appearance: golden yellow in color and very clear. Specific :oravity (sete (oe) nee 0.941 Retractivesindexn( ois Gy one ton cia I. 5195 1 Circular No. 195, “Amer. Tung Oil Culture,’ Henry A. Gardner. * Analyzed by Dr. T. T, Ling, Research Chemist. CHINA WOOD OIL 221 Peepersion, Valle (o5".G,) oo set: ey 0.02129 Acid Number in Alcohol-Benzol......... peie Iodine Number (one hour Wijs) ........ 175 BPaPOMMICALON VAlUEs Msc ken ks ok A on. 195.5 Feats best (100 em, Worstall’s) 2). )/2,. 62 minutes The gel is very pale in color, dry and firm; cut and crumbled very well. This sample is pure tung oil of ex- ceptionally good quality. One half of this sample was sent to Dr. Z. Z. Zee at Columbia University whose analysis of this oil is as follows: Color: very light amber. Odor: faint but characteristic. SO) LeU ee a eae i 0.9428 (at 15.5°C.) Per elaldere yr eek 4 Te5204at 25" Cy) PITS METAION exe C2 aig ees 0.02068 yental DSie noe. NP Aah Gare le, POC IMCMNO Ss eS is cts 174 Heat Test.............. 9#minutes (Browne’s Jelly test, heating at 282° C.) “The quality in my opinion is excellent.” When Havana tobacco from the Vuelta Abajo district, which is acknowledged the finest tobacco in the world, was transplanted to Connecticut and Wisconsin, totally different tobacco was produced which did not even appear like the original, and yet, from the coarse strong tobacco which was originally produced in Connecticut that sold at a few cents per pound, by selective transplanting and proper fertilizing, tobacco is being produced which commands as high, and in some instances, a higher price, than the original Havana tobacco. The transplantation of the French grape to California produced a wine twice as strong in alcohol as the original. Chinese cotton differs from the Egyptian and American cotton. Any indigenous plant transplanted in various parts of the world becomes either better or worse 222 CHEMISTRY AND TECHNOLOGY OF PAINTS than the original, but it usually has an entirely different taste, flavor, or characteristic. It is quite natural, there- fore, that tung oil grown in America will be different from tung oil grown in China, and, from present appearances, it will be an oil that is going to be much more uniform and paler in color than anything grown in China. New formulae and methods will have to be devised, as the American oil polymerizes more rapidly and the addition of organic acids or possibly fatty acids in conjunction with rosin may have to be adopted in order to extend the time of polymerization or prevent it entirely, if possible. Unless China wood oil varnish is heated in a kettle above 260° C. and kept there without polymerization, the resulting varnish will only be good in the summer time but not good in our or in other winter climates, for instead of drying with a high gloss it flats selectively, and the only prevention for the flatting of China wood oil where it is not wanted, is to heat the oil without polymerization to a sufficiently high temperature and keep it at that in the presence of organic acids. Fatty acids of linseed oil and rosin are best adapted for the purpose. The standard method for making wood oil varnish in the case of rosin, is 100 pounds of rosin to 400 pounds of wood oil, but in the case of rosin ester, the standard formula is 150 pounds of rosin ester to 400 pounds of wood oil. DEODORIZATION OF CHINA Woop OIL It is possible to deodorize China wood oil and rid it of its pernicious characteristics, but up to now it has not been possible to do this on a commercial scale, for there are many difficulties that arise in any process which attempts to extract the material that produces so-called “heathen smell.” CHINA WOOD OIL 223 China wood oil as grown in America has a very pleasant characteristic odor because the nuts are not allowed to rot and no decaying animal matter can possibly find its way into the American material, but on the Yang-tse River it has become essential to strain the oil as it is poured out of the baskets, through iron wire gratings in order to rid it of any foreign matter, including dead animals. Starting out with the assumption that the odor is pro- duced by some material which has an analogy to butyric acid or a butyric compound, a large number of samples of oil were heated up to 150° C. and nitrogen and other inert gases were bubbled through them. In every case a reduction of the odor was noticed, but after the oil cooled and was allowed to stand in the light, it changed from a colloid to a crystalloid and, at first, fine crystals began to float around in the oil until, after 48 hours, the oil had the appearance of a soft wax. A large number of experiments were tried, adding materials of carbonaceous nature, heating and blowing the oil at the same time, and after filtration the oil became crystalline, and in every instance this condition rendered it unsalable. Air, steam and some of the inert gases pro- duce good results but the oil undergoes a change. This work is worthy of further study and experimentation. LUMBANG OIL This oil will be suited for paint purposes as soon as care is exercised in the collection of the nuts, which grow in great quantities in the Philippine Islands. As yet, no definite statement can be made as to its constants unless a sample of oil is extracted from clean nuts, as such a sample will differ from the material that is imported into the United States at present. It has been used in some considerable 224 CHEMISTRY AND TECHNOLOGY OF PAINTS quantities for the purpose of making putty, but there is no reason why it should not be used for paint, as it dries well, has a high iodine number, and, in spite of the method by which it is handled, it has a low acid number. The specific gravity varies from .930 to .940; saponi- fication value from 190 to 200; iodine value from 160 to 170. STILLINGIA OIL Stillingia oil is obtained from the seeds of stidlingia sebifera, native to several parts of China. It is expressed from the seeds after the outer shell and mesocarp have been removed, and is generally of dark color, due to the primitive methods of extraction. Oil of a good pale color can be obtained by more modern treatment. Tallow seed oil or vegetable tallow is expressed from the mesocarp surrounding the seeds. It is also obtained by pressing the entire nut, seed and all. This oil, which is not-of much interest to the paint and varnish industry, is used in China as a substitute for cocoanut oil and tallow in the manufacture of candles and soaps. Stillingia oil was formerly used only for lighting pur- poses, but is now widely used in China as both a substitute and adulterant for tung oil. Hard drying, glossy varnishes are made of it, CHAPTER’ XV. SoYA BEAN OIL! FRoM 1890 to 1909 the price of linseed oil fluctuated between 30 cents and 50 cents per gallon. On a few occasions the prices were higher, but a fair average for the 19 years was 4o cents per gallon, although in 1896 it went as low as 25 cents. ‘Toward the end of 1909 it rose from 60 cents to 68 cents within two months, and in September, 1910, it reached $1.01 per gallon. After that it fluctuated between that price and 75 cents. Owing to the high price of linseed oil in t910 many painting operations were deferred awaiting a lower price, or inferior material was used in place of linseed oil. The value of menhaden fish oil had already been recognized, and while it is admitted that fish oil replaces linseed oil for many purposes, it is by no means a true substitute. The principal use, however, for fish oil to- day is in the manufacture of linoleum, printing inks, and certain paints which are exposed either to the hot sun or on hot surfaces. In 1909 soya bean oil as a paint oil was practically unknown. Since that time many investigators have published more or less conflicting articles concerning soya bean oil, in which even the physical and chemical constants of soya bean oil varied to some extent. Owing to the fact that discordant results were continually ob- tained, it is only within the past few years that it has 1 Journal of Society of Chemical Industry, June 29, 1912, No. 12, Vol. XXXI, by Maximilian Toch. 225 226 CHEMISTRY AND TECHNOLOGY OF PAINTS been possible to state with some degree of certainty whether soya bean oil is a substitute for linseed oil, an adjunct to it, or neither. The reason for this uncertainty and discrepancy is apparent when it is stated that the author himself has experimented with 33 different varie- ties of soya beans, while in the records of the Department of Agriculture at Washington no less than 280 varieties of soya beans are listed. | From time immemorial the soya bean has been grown in China and Japan, where it has served as one of the staple articles of food and as the basis for a number of food preparations. In Europe and the United States, however, the value and uses of the bean have been but little appreciated until very recently (1908), when, on account of the scarcity in the cotton seed supply of the world, soap and glycerin manufacturers began to turn their attention to its possibilities. In Manchuria, where by far the major portion of soya beans are grown, practically the entire crop is available for export. The following figures taken from the Consular Reports will serve to show the extent of the soya bean industry during recent years: 1909 IQIO IQII Tons. Tons. Tons. Total shipments of beans from Far; Kast 2a eeyee sare 1,470,870. ~I,200,000 = I, 500;0@0 Importediinto Hurope = een 400,000 500,000 340,000 As the above statistics indicate, China and Japan retain for domestic consumption practically two-thirds of the available supply of beans. The sugar plantations in Southern China and the rice fields of Japan annually consume enormous quantities of soya beans and bean cake as fertilizer, while the extracted oil is used as food by the natives. SOYA BEAN OIL 224 In connection with the use of soya beans and soya bean oil for edible purposes, it may be mentioned that there has been recently established at Les Valées, France, a thoroughly up-to-date factory for the production of a wide assortment of food products from soya beans. Among the more important of these may be mentioned: milk, cheese, casein, oil, jellies, flour, bread, biscuits, cakes and sauces. According to Dr. G. Brooke, Port Health Officer of Singapore, the soya bean, more nearly than any other known animal or vegetable food, contains all the essential and properly proportioned ingredients of a perfect diet. All soya beans are leguminous plants, which do not tend to deplete the soil of nitrogen, for the typical soya bean plant is self-nitrifying and grows in almost any soil that contains a reasonable amount of potash. In addition to this, the soya bean enriches even very poor ground when used as a ground manure. This is done by planting the seed promiscuously, allowing it to grow to a height of about 6 inches, and then turning it in. In this way both nitrogen and potash are given to the soil for future use in an available form. The average height of the soya bean plant is about 36 inches. The pods resemble those of our sweet pea. They. are about 23 inches in length and are covered with a hairy growth. Generally there are two or three beans in each pod. After the oil is extracted from the bean the cake ‘appears to be very valuable as a cattle food, while the leaves and stalks, if collected and set in a dry place, make excellent silage. We thus have practically the entire plant available for use, with the exception of the roots. The average composition of the soya bean varies with- in fairly narrow limits among the different varieties 228 CHEMISTRY AND TECHNOLOGY OF PAINTS of soya beans. In the following table are listed the analyses of a few of the varieties of soya beans:! | Nitro- Variety Water | Protein Fat gen free Fibre || _ Ash extract Zo %o % Yo Zo Zo AUSEIDG, speiae e007 30.50 20.55 24.41 4.00 5.78 [to"Sate eee 7542 34.66 19.19 27.61 5.15 5-07 Kingston \2. =. ipo 36.24 18.96 26.28 4.79 6.28 -Mammoth....| 7.49 32.99 21.03 20.36 4.12 5.8 Guelph savers 7.43 33.96 Den 72 25.47 4.57 $.85 Med. Yellow..| 8.00 | 35.54 19.78 26.30 4.53 5.05 Samarow..... Bie 37.82 20.23 23.65 5-05 5.82 When the author obtained discordant results from the soya bean oil then on the market, the first impression was that the oil might have been adulterated, but this did not prove to be the case. The oil was, in all cases, pure soya bean oil, but from a seed which was not par- ticularly adapted for making a paint oil. Through the U. S. Department of Agriculture many varieties of seeds were received, and through the various seed dealers in the United States quantities of seeds of all kinds were purchased. The method of extraction followed was to grind the seeds very finely in a mill and digest with gaso- line in the cold. The solvent was then evaporated and the oil recovered. Without going into any lengthy de- tails, the percentage of oil extracted averaged 18 per cent, and although soya beans range in color from a cream white to a jet black it must be noted here that all the oils extracted from the various seeds were paler than finely pressed linseed oil, and none of them showed the ' U.S. Dept. of Agric. Bulletin of the Bureau of Plant Industry. DOVA SBEAN ‘OLE 229 chlorophyll extract as markedly as fresh flaxseed. On obtaining the various samples of oil it became evident why the discordant results were obtained, for some of them dried within a reasonable time and some did not. It has been stated that soya bean oil is not as pale as raw linseed oil and belongs to the semi-drying class of oils. I must correct this statement; soya bean oils made from cold pressed seeds such as Haberlandt, Austin, Habaro, Ebony, Meyer, and Ito San give excellent results. They have a specific gravity as high as 0.926, with a yield fareineeitom«r0 10 19 per cent. Furthermore, a drier made from red lead or litharge is unsuited for soya bean oil, but a tungate drier, which is a mixture of a fused and a precipitated lead and manganese salt of China wood oil and rosin, acts on soya bean oil exactly the same as a lead and manganese drier acts on linseed oil. In other words, a fairly hard, resistant and perfectly dry film is obtained within 24 hours by the addition of from Butoey7eper cent of this drier. Soya bean oil, and when I mention this name here- after, I refer only to that suitable for paint purposes, ieeeties nearest, oil we have «to linseed, and- under the proper impetus of the Department of Agricul- ture much of our waste and_ unproductive land between Maryland and Georgia, and from the Coast to the Mississippi, will yield productive and _ profitable crops. The only drawback to the planting of soya Pedueise the fact ». 0.9227 143.0 Menhaden Oil atta pieached winter, «). +. 0.9237 150.4 Ate e te TCTINCC to yc 0.9273 161.2 hagas Jub Wee“ cele 3 an all ay ai 0.9249 165.7 PP EROLOWN. cM sa ee ce 0.9250 154.5 The specific gravities were determined with the aid of the Westphal balance. The iodine numbers were determined peor dine to the standard method ‘of Hiibl. The fish oil used for paint purposes is the variety obtained from the Menhaden fish, and the winter bleached is the variety to be recommended. When refined by the simple process of filtering through infusorial earth and charcoal its color is that of refined linseed oil, with - little or no fishy odor; in fact, in the purchasing of fish oil for paint purposes it is well to beware of a fish oil that has the so-called characteristic “fishy”? odor. In its chemical properties it is so similar to linseed oil that it is difficult to differentiate between them. It must be observed that oils in mixed paints are not presented to the chemist or practical man in their raw or natural state, but they have been boiled with driers and ground with pigments so that their characteristics are entirely 238 CHEMISTRY AND TECHNOLOGY OF PAINTS altered. The old-time painter when he condemned a mixed paint would smell it, taste it, rub it between his thumb and forefinger, smell it again, look wise, and say despairingly, “fish oil.”’” As a matter of fact, the adul- teration of paints was seldom, if ever, caused by the addition of fish oil, for the reason that the price of a good fish oil always approximated that of a raw linseed oil, and there were so many other cheaper paraffin oils to be had that the occurrence of fish oil in a mixed paint was relatively rare. The specific gravities of fish oils freshly made and containing no admixture of other species, but representing the pressing of only one species, are aS a general rule below .g27. Its iodine number is so close to that of linseed oil that in its raw state, except- ing for its characteristic odor and the Maumene test, it is rather difficult to differentiate these oils with cer- tainty. The author is inclined to believe that this characteristic odor is due to phosphorous decomposition compounds. If a linseed oil be heated to 500° F., mixed with Japanners Prussian brown or Prussian blue, it de- | velops acrolein, which is identical in odor with that from the fish oil. When Menhaden oil is treated with 8 ounces of litharge to the gallon and kept at a temperature of 400° to 500° F., for ten hours, it thickens perceptibly and can be reduced proportionately with naphtha, but the amount of loss by this treatment with litharge makes it very expensive in the end. The results obtained from the proper grades of fish oil warrant the use of fish oil in the hands of an intelli- gent manufacturer, and if used up to 75 per cent pro- duces excellent results for exterior purposes. For interior purposes fish oil does not seem to be desirable, for it gives off noxious gases for a long time. When fish oil is mixed with linseed oil even up to 75 per cent it FISH OIL 239 gives excellent and lasting results and does not show any hygroscopic properties, but when used in the raw state, particularly in conjunction with pigments which in themselves are not catalytic driers, the results are not satisfactory. For some years some of the enamel leather and print- ing ink manufacturers have adopted the use of fish oil as a medium to replace linseed oil with excellent results, and the enamel leather which is produced, while not so high in gloss as that made entirely of linseed oil, is much more flexible and possesses an unctuousness which pre- vents it from cracking. But fish oil for leather purposes shows a peculiar defect, and a campaign of education will be necessary if ever this material is to be used for the manufacture of shoes or auto tops, for fish oil, par- ticularly when it originally has a high acid number, seems to effloresce and give an undesirable bloom to enamel leather, which, however, can be removed from the sur- face by the ordinary application of either benzine or a mixture of benzine and turpentine. At the same time, enamel leather is very largely used for carriage and automobile tops, and for shoes, and wherever it is used for these purposes these products are continually polished. Menhaden oil is the only oil, with the possible excep- tion of China wood oil, which can be used for making ‘ smoke-stack paints that will withstand the action of excessive heat and light. When treated as described, its intrinsic value is far beyond that of linseed oil, and a smoke-stack paint made in this manner sells for one-third more than a linseed oil paint. It is impossible, however, to treat Menhaden oil for this purpose, except at an excessive cost, because the acrolein developed nauseates the workmen, the loss in evaporation is very large, and the treatment with litharge is such that the oil must 240 CHEMISTRY AND TECHNOLOGY OF PAINTS be thinned before it has an opportunity to compound or semi-solidify. In its raw state, after treatment with animal charcoal and infusorial earth, it is used to ‘some extent with a heavy boiled linseed oil for making water- proof roof paints, for painting canvas, freight cars, ship decks, etc. When mixed with linseed oil up to about 25 per cent it is extremely difficult to determine the amount present by means of its chemical constants or characteristics. The following are the constants of the Menhaden oil which is generally used in the United States for making ~ heat-resisting paints: CONSTANTS OF FISH OIL Specific Gravity a5 acne eee 0.931 paponificationns © a. ee ear ae QO. lodine Value ..7 ues 4c ee 150-165 There is a great demand for baking japans which shall be flexible and at the same time be so thoroughly baked that they adhere to the surface most tenaciously and form an excellent enamel, and for this purpose we know that the reasonable use of fish oil improves baking japans very much indeed. We are also aware that along the seacoast, where paint disintegrates very rapidly on account of the sea air, a fairly liberal use of properly treated fish oil serves a useful purpose. When red lead is mixed 33 lbs. to a gallon of linseed oil it thickens up after a very short time and becomes unfit for use. A properly neutralized fish oil prevents the hardening or setting of the red lead in the package, and a paste of this material can be transported a great distance and will last many months in a fresh and soft condition. FISH OLL 241 In the tests made by the author on fish oils and tin- seed oil without the admixture of driers, it was found that the Menhaden fish oil and the linseed oil dried approxi- mately the same, but the seal oil and whale oil were still sticky after two weeks. This may be an unfair test, for these other oils can be manipulated with the proper driers and they will serve a fairly good purpose, but inasmuch as Menhaden fish oil appears to be satis- factory for this test even without a drier its superiority over the animal oils is apparent. Menhaden oil should, of course, be used with a drier, and for that purpose the best results are obtained by means of a tungate drier. A tungate drier is one in which tung oil or China wood oil is boiled with a lead and manganese oxid, and when the solution is complete this is then mixed with a properly made resinate of lead and manganese. Such a drier becomes soluble in the oil at temperatures over 100° C., and hardens the resulting paint very thoroughly. For fabrics, however, fish oil must be heated to a temperature of over 200° C., and if air is injected at such a temperature the glycerides are expelled and thick oil is produced which, in con- junction with the drier just named, is equally good for printing inks. It is advisable, however, to add at least 25 per cent of either a heavy bodied linseed oil or a raw ‘linseed oil which does not “break”’ before the manipula- tion just referred to is begun. For stacks, boiler fronts, etc., the treatment of fish oil up to 220° C., with litharge makes a heat-resisting medium that is far superior to anything excepting China wood oil, and for both heat-resisting and exposure to the elements fish oil is superior to China wood oil. The following is taken from the U. S. Navy Depart- ment specifications for fish oil for paint purposes: 242 CHEMISTRY AND TECHNOLOGY OF PAINTS Quality 1. To be strictly pure winter-strained, bleached, air-blown Men- haden fish oil, free from adulteration of any kind. Chemical Constants 2. The oil shall show upon examination: Maximum Minimum Specie STAVILY sce eo eee 0:935 6.030 Iodine number (Hanus)....... 165 145 Acid number sav. aene eee TE Physical Characteristics 3. The oil when poured on a glass plate and allowed to drain and dry in a vertical position, guarded from dust and exposure to weather, shall be practically free from tack in less than 75 hours at a temperature of 70° F. When chilled, the oil shall flow at temper- atures as low as 32° F. Among the best fish oils is the sardine oil of the north- west coast of the United States which has an iodine number as high as 175. When this oil is heated in a glass vessel with 10 per cent kerosene or an equally slow drying petroleum distillate a large part of the odor of the oil appears to be carried off. Sardine oil to which 25 per cent of China wood oil varnish has been added has given excellent results as a smokestack paint and the same may be said of the addition of perilla oil to sardine oil, but in each case and for hot stacks 3 per cent of a good liquid drier should be added. The northwest oil is similar in all its characteristics to the Japanese herring oil described in the foilowing chapter. CHAPTER eX VIL MISCELLANEOUS OILS HERRING OIL! WITHIN recent years the subject of fish oils has received considerable attention, first from the leather and soap manufacturers and subsequently from the paint chemist. Hitherto fish oil played the réle of a rather un- important by-product in the course of fertilizer or ‘‘scrap”’ production, for which there seems to have been always a large demand. As the peculiar properties and industrial possibili- ties of fish oils became more thoroughly appreciated in the light of investigations carried out by progressive manufacturers, the fish oil industry received a new lease of life and grew until it rivalled in, importance the fertilizer industry to which it had previously been tributary. Of the numerous varieties of fish oils which have at one time or another appeared upon the market, Men- haden oil alone seems to have established itself on a firm basis in the manufacture of special kinds of heat-resisting paints. Its application, therefore, is no longer an experi- ment; it is an established fact. : Latterly, attention has been more particularly directed toward seal, whale, cod, porpoise, and herring oils, with 1 By A. Lusskin, 8th Int. Congress of Applied Chemistry; written in the research laboratory of Toch Brothers under the direction of the author. 243 244 CHEMISTRY AND TECHNOLOGY OF PAINTS a view to investigating their utilizability in the indus- tries. Of these, seal, cod and porpoise body oils have proved to be in many ways as good as Menhaden oil, but are beyond the reach of the paint manufacturer on account of considerations of price. Whale oil, which is now obtainable in the form of a clear, pale material, comparatively free from objection- able odors, has not as yet been successfully manipulated to give very good drying results. In the treatment of fish oils, several considerations must be constantly kept in mind in order to obtain the best results: 1. The oil must be free from high melting point glycerides or fatty acids; or, to use the technical term, the oil must be “‘winter-pressed.”’ Most fish oils contain a large amount of saturated glycerides of the nature of palmitin which separate from the oils on standing for any length of time at a low temperature. When these have been removed from the oil, the resulting product is found to be much more amenable to successful treatment than it otherwise is. It would seem that these high melt ng point fats tend to retard or to prevent the drying of fish oils, giving films which remain greasy for a very long time. | 2. Very frequently, oils are received which have a high content of free fatty acids. In the case of one sample of herring oil, this was as high as 41.9. Under such circumstances, it is perfectly evident that the drying of the oil would be very largely inhibited. In addition, such an oil, used as a paint vehicle, in conjunction with pigments like red lead, white lead, and zinc oxid will, in a very short space of time, “liver” up and form the lead and zinc soaps of the fatty acids. This was very largely responsible for the poor results obtained with the HERRING OIL 245 fish oils which were first introduced on the market. The free fatty acids are formed when the oil, extracted from the fish by boiling in water, is subjected to the action of the decomposition products from the bodies of the fish for a longer time than is absolutely necessary to break open the oil-containing cells. 3. Finally it must be remembered that driers, which serve very well for vegetable drying oils, will not, in general, function properly, when utilized for fish oils. The tungate driers, and particularly the cobalt tungates, can generally be depended upon in the case of oils which do not yield to the action of the ordinary linseed oil driers, provided however, the two conditions named above have been satisfied. The writer recently had his attention called to several grades of herring oil, which, at first glance, appeared desirable from the paint manufacturer’s standpoint. Accordingly an investigation was started to test its adaptability for paint purposes, and to compare its be- havior with that of Menhaden oil. | Herring oil occurs in the bodies of Clupeus C. and V. (Japanese herring varieties) and Clupeus harengus (European or North Sea herring). The method of extracting the oil from herring is the one universally used in the fish oil industry, viz., ex- .traction in boiling water. 2 Two representative samples of herring oil, furnished by two of the leading oil concerns in the States, were experimented with in conjunction with Menhaden and other fish oils. The following analytical constants were obtained: 246 CHEMISTRY AND TECHNOLOGY OF PAINTS No. Color Odor Sp. Gr. | Acid | Iodine 15°C | Value| Value #1 Herring Oil Very Pale Good 0:0240)| 2254 aie 7e0 #2 Herring Oil Dark Brown Bad 0.0210 P4r, Quai ore Blown Oil #2 Deep Red | Almost | 0.9654| 25.7) 89.94 None Winter-Pressed dL Extremely Fair O.920:.| 30.4, -140.8 #i Crude Whale Oil | Very Pale Good, «| 0.92307] ©20)} 430.5 #1 Filt. Whale Oil | Very Pale Good ©. | 0.020395 223i 7eec #2 Filt. Whale Oil | Pale Amber | Very good | 0.9222 | 14.5 | 142.9 Porpoise Body Oil Very Pale | Very good | 0.9268] 2.8 | 132.3 Menhaden Oils Ext. Bleached Winter Oil Very Pale Fair 0.0272) O7ns et somd Bleached-Refined Pale Amber | Not bad | 0.936345) 57g pom Regular Deep Red Bad 0.9284 | 8.4) 165.7 * The part of the table below the asterisk (with exception of the acid values), is from a paper on Fish Oils delivered by M. Toch before the Amer. Chem. Soc., Dec. 1911, and published in the Journal of Industrial and Engineering Chemistry. Crude herring oil, even though very dark in color, yields a very clear, pale product when treated with Fuller’s earth for a short time at about 250° F., and then for some time longer, at the temperature of boiling water. In addition the odor is considerably improved. In the case of the crude herring oil listed above, the sample was kept for several hours at about 60° F. to permit high-melting fats to separate out. The portion which remained liquid corresponded to a winter-pressed oil. Since the acid and iodine numbers were prac- tically unchanged it seems that the solid fats contained saturated and unsaturated compounds in about the same proportions as the crude oil. CORN OIL 247 Another sample of the oil was heated to 320° F. and blown with air for about 8 hours. The effects produced on the constants are shown above. The oil was very heavy and viscous but had the deep red color which fish oils so readily assume. It must be noted also that the “fish”? odor was very faint. The reduction in acid value would seem to indicate that the oil contained fatty acids which were volatile at the temperature of blowing. Attempts to dry the samples of herring oil did not prove successful, even when very powerful driers were used. This cannot, however, be interpreted to mean that herring oils are, in general, not- capable of drying. Porpoise body oil and Menhaden oil, under similar conditions, dried satisfactorily. The blown herring oil could very well be used for the production of smoke-stack paints and for paints intended to resist the ‘“‘chalking”’ action of salt air. Herring oil is at present used to a certain extent in leather manu- facture together with some of the other fish oils like Menhaden and whale oil. In regard to herring oil, as with many of the other materials which are being intro- duced from time to time, the final word cannot be spoken until many more specimens have been examined and given a fair test. CorN OIL Corn oil is made in very large quantities in the United States, and is of considerable value as a paint material. It is seldom so much cheaper than linseed oil or China wood oil that it is used as an adulterant for these oils; in fact, many manufacturers would probably use it irrespective of the price up to about to per cent in certain classes of mixed paints in order to prevent hardening or settling. A large number of paint manu- 248 CHEMISTRY AND TECHNOLOGY OF PAINTS facturers in the United States who grind heavy paste paints, such as Venetian reds, ochres and white paints containing large amounts of barytes, frequently use from Io to 70 per cent of corn oil, not because it is any cheaper than linseed oil, but for the reason that the resulting mass never becomes hard in the package as it ‘does where pure linseed oil is used. Corn oil has a great analogy to soya bean oil, with the one exception that corn oil is not as pale nor can it be bleached as pale as soya bean oil, and when it is bleached by chemical means it dries very badly. Corn oil is known in England as maize oil. Paint manufacturers in England appear to have very little knowledge of this oil and regard it as a non-drying oil, and yet corn oil is even more than a semi-drying oil, particularly when heated with strong drying oils like China wood oil and cobalt and manganese drier. In the textile arts, such as the manufacture of linoleum and table oilcloth, where flexibility is desired, large quantities of corn oil are from time to time used with excellent results. When an oil like corn oil is used for paint purposes in limited quantities its characteristic of slow drying or tacky drying is eliminated if it is properly ma- nipulated. Corn oil will take up the lead and manganese salts just the same as linseed, but in conjunction with linseed oil. It can be blown and can be thickened by heat, and being very flexible it has a distinct advantage. It has been stated, although the author has not tried this, that for priming new wood half corn oil and half linseed oil with sufficient drier and volatile solvent produce a priming coat to which a second coat of linseed oil paint will adhere perfectly. The physical and chemical constants of corn oil cannot be given exactly for the reason that samples vary. CORN OIL 249 Its specific gravity will run from 0.920 to 0.926; its saponification value will average 190; and its iodine value will average 120, although several samples exam- ined by the author have shown as high an iodine value aS 130. CHAPTER XVIII TURPENTINE TURPENTINE occupies the same relative position among the vehicles of paints and varnishes as white lead does among the pigments. It is impossible to say for how many generations turpentine was the only solvent or diluent known to the paint and varnish industry, and therefore when other solvents were introduced they were looked upon as adulterants. The methods used in the manufacture of turpentine are very well known; the sap of the Georgia pine and two or three other species of pine trees growing in the southern part of the United States is collected and distilled with steam. The distillate is known as turpentine, and that which remains behind in the still is known as rosin (colophony). American turpentine has a very pleasant odor, and from several combus- tion analyses made by the author, the composition of turpentine taken directly from the barrel as shipped from the South corresponds absolutely with the theo- retical formula CiHis. It has absolutely none of the qualities of a paint preservative, but is used only to increase the spreading power and working quality of paint. Entirely too much stress is laid upon the value of turpentine as a paint vehicle, and the sooner the chem- ist and the consumer realize that turpentine is simply an auxiliary, the sooner will better substitutes be used. If the forestry department of this government will not interfere with the destruction of the trees, turpentine will become a chemical curiosity within the lifetime of many of us, unless new trees are planted. 250 TURPENTINE 251 -American differs from Russian turpentine in odor and in specific gravity, although in chemical composition they are alike. The specific gravity of American turpentine is about .865 when fresh, but it will rise as high as .90 when old. It is supposed to boil at 350° F., but that also depends very largely on the condition of the turpentine and whether it has been exposed to the air. Turpentine flashes according to the text-books, and according to the majority of specifications that are written, at 105° F. As a matter of fact, its flash point is 98° F. Turpentine evaporates very slowly, and on account of this slow evaporation it is very highly prized as a varnish diluent, but there are paraffin products that have lately been invented that evaporate just as slowly and leave no resi- due behind. Pure turpentine when poured on a sheet of filter paper should leave absolutely no residue behind, and a drop of water poured on the paper after the tur- pentine has evaporated must be absorbed as readily by the paper as before it was immersed. In this regard the petroleum naphtha solvents are identical. They will be described in the proper chapter. The following organic analyses of French, American, and wood turpentines show that French turpentine and American turpentine are both represented by the for- mula C,oHis, the American turpentine being practically ‘ 100 per cent pure. Wood turpentine, however, may be shown to be 97.7 pure, the 25 per cent of impurities con- sisting of pyridene bases, formalin, and other wood decomposition products. Since these investigations were made in 1905, samples of wood turpentine have been placed on the market which are so nearly identical with the sap turpentine that it is almost impossible to dis- tinguish them, only an experienced consumer being able to tell the difference, the wood turpentine having a pe- 252 CHEMISTRY AND TECHNOLOGY OF PAINTS culiar odor which is lacking in the sap turpentine.- No matter how thoroughly a wood turpentine is purified, there is always a smell of sawdust which clings to it and which can be recognized by a person once familiar with the odor. These pure grades of wood turpentine cannot be said to be adulterants of the sap turpentine. FRENCH TURPENTINE First Analysis Second Analysis Weight of sample............0.2040 grams. 0.1870 grams. GOs obtained sr jeer 0.6558 grams. 0.6009 grams. HO obtained va. sae ©. 2161 grams. 0.1980 grams. | Hence, percentage composition, Carpon kine ot oe ee 87.67 per cent. 87.63 per cent. Hydrogen.) 25 328 eee 11.87 per cent: 11.87 per cent. ‘Potalinoe eos reer 99.54 per cent. 99.50 per cent. AMERICAN TURPENTINE First Analysts Second Analysts Weight of samples... .2 s..20n17 77 erm, 0.1828 grams. CQ. ‘obtainediae am eee 0.5714 grams. 0.5878 grams. HO obtained. we eee ©.1923 grams. 0.1968 grams. Hence, percentage composition, Carbon 4a. See eee 87.70 per cent. 87.69 per cent. Hydrogen sie eee 12 -12*per cent: 12.07 per cent. Total idee oe 99.82 per cent. 99.76 per cent. Woop TURPENTINE First Analysis Second Analysts Weight of samplé......) 20,100 eramns. 0.1656 grams. COs; obtained 365; sence es 0.5939 grams. 0.5202 grams. HO obtained 4: = omen ee ©. 2042 grams. 0.1785 grams. Hence, percentage composition, Carbon. tigen tomer eee ee 85.65 per cent. 85.67 per cent. Hydrogen, 3. a eee 12.10 per cent. 12.08 per cent. Oxygen. a ee 2 eee cents 2.25 per cent. Dotal act, ae seeee 100,00 per cent. 100.00 per cent. TURPENTINE 253 In the Journal of the American Chemical Society ! for 1904 a very exhaustive treatise is given on spirits of turpentine, in which it is demonstrated that the only reliable chemical test for differentiating between’ wood turpentine and the old spirits is the determination of the iodine absorption number. But even this is now growing to be very unreliable, for the reason that so much care and skill is exercised in the manufacture of wood tur- pentine that it is almost impossible to distinguish it from the sap turpentine. A great deal has been written on the optical activity of turpentine when observed through the polariscope. The paint chemist, however, cannot point with any degree of certainty to this test, excepting where a coarse mixture of benzine, rosin oil, etc., is made, and up to the present writing very highly refined tur- pentine and sap turpentines show little or no difference. The admixture of rosin oil, benzine, benzene, kerosene, and adulterants of that kind are, of course, differentiated with more or less ease. Turpentine is by no means used as largely as it was prior to 1906. The reason for this, strange to say, is a moral one and not a physical one. Ten years ago it would have been thought impossible to do without spirits of turpentine in paint or varnish. Today it is used by many people who think they have to use it, and by others ‘who use it in high grade piano and other finishing varnishes, because they believe it gives a physical flow to the varnish which cannot be obtained by the use of anything else. This, however, is disputed by many manufacturers. At any rate, the fact remains that several years ago turpentine rose from a price of about 40 cents per gallon to $1.13, for a number of men in the southern part of the United States attempted to corner the market. Before, how- 1 “ Analysis of Turpentine,” by Jno. M. McCandless, p. 981, 1904. 254 CHEMISTRY AND TECHNOLOGY OF PAINTS ever, the price reached the abnormal figure of $1.13 some of the officials of the United States Navy made exhaust- ive experiments and showed that the turpentine sub- stitutes of the petroleum type were absolutely as good and served the same purpose as spirits of turpentine. Not to go into the details of this, about five years ago the United States Navy substituted some 70,000 gallons of turpentine by turpentine substitute, and the resulting paint gave just as good service and the saving in price was very great. The men who had attempted to corner the market and enrich themselves at the expense of others were finally ruined, and the whole turpentine industry received a staggering blow, from which at this date it has not entirely recovered. The price dropped until it hovered around 4o and 50 cents, but in the meantime the paint industry had learned the lesson, which was of tremendous value, that it could do without turpentine entirely. TURPENTINE ! Distillation of Pure Gum Spirits of Turpentine Will not begin distilling lower than 153° C. t. to 2% distills over by 153° C. 50% 66 66 66 I57- Ge 80% Ts 6c 6c Tos re 85% és ST STOCm es 95% 6c ‘< qs 165.5° oO Sometimes 50% 6“ 6“ 66 159° CX 80% a (Coe TOO Rae 85% ts £6 SC 65 95% should be distilled by 165.5° C. * Data from J. E. Teeple, New York City. TURPENTINE 255 Distillation of Steam Distilled Wood Turpentine Usually begins distilling at about 0535.0, 50% distills over by (eo eh Or eae TOA se, 85% . Bee tones C, 95 % “ce ce ope CG. Sometimes 80% CT: 6 6c 163° CG 85% (79 ce (73 164° C. 90 % cc ¢ ce LOG-RS Cs a9 (79 c¢ O° = a 95% ate - No. tor. Section of the long leaf turpen- This latter would be con- sidered a very good grade. Sometimes only 60% to 70 % will distill by 165.5° C.— Poor grade. tine pine — Photomicrograph X310. Woop TURPENTINE The turpentine in the United States is held in such strong hands that the price is abnormally high, and within the last five years pine, sawdust, shavings, tree stumps, and old logs have been placed in retorts and distilled in the same manner as the sap of the pine tree. A liquid is obtained which is sold under the name of wood tur- pentine and is guaranteed by many to be absolutely the same material as that obtained from the sap of the tree. It must be frankly admitted that there are some wood turpentines on the market at this writing which are so similar to the real article that it is almost impos- sible to differentiate between them. And yet there is always a peculiar distinctive odor to these wood _tur- pentines which does not exist in the pure turpentines. Several organic analyses of this variety of wood tur- pentine by the author have shown that the formula is not CioHi., but that it is a most complex mixture con- taining more than a trace of pyridene bases, formic acid, 256 CHEMISTRY AND TECHNOLOGY OF PAINTS formaldehyde, and other products from the destructive distillation of wood. But wood turpentine is being improved so continually that these impurities are being largely removed. For exterior painting, wood turpen- tine that contains only a trace of these impurities is No. to2. Cross AND LONGITUDINAL SECTIONS OF WHITE PINE— Photomicrograph X180. just as good as the sap turpentine, and for indoor paint- ing it is no better than a number of the petroleum products and costs very much more money. It cannot be said that it has advantages in exterior painting .over the benzine products. One reason why it can be used on exterior work and not on interior work is that the dis- agreeable odor it sometimes gives off becomes obnoxious to those who use it on interior work. The pure grades TURPENTINE 257 of wood turpentine cost within 5 cents per gallon of the price of sap turpentine, and judging from the large number of concerns that have sprung up within the last five years for the manufacture of wood turpentine and then slowly disappeared, it is reasonable to infer that the industry is not profitable. PHYSICAL CONSTANTS OF TURPENTINE, TAKEN FROM BeeCAPICATIONS OF THE U.-S.. NAVY DEPT., 1923, AND THOSE OF THE AMERICAN SOCIETY FOR TESTING MATERIALS, 1924 Maximum Minimum Sreeoabdavity, 15.s/T5 Cl.) ok. 10, 875 0. 862 Refractive Index at 20° C. STEEL SSF Bch ae ee 1.478 1.468 NV ROOCIMPSTEDCTN GING seh reir cea Pk oe en. 1.478 1.465 Residue after polymerization with 28 NHe SO,: Gum spirits — Poitier percelts se . e, as. eS 2 Omsene te a ieeeze emicuvemndex-at 20° Con)... 205s. ee. I.500 Wood turpentine — PD rPMeE OCI CCl Ur ia Leas. ante ot we BCR toes feetracuve Index at 20%.C...; Js 2. 2 1.48 Initial boiling point at 760 mm. pressure. 1.60°C. 150°C. Distilling below 170° at 760 mm. pressure, | Nie BUSLat 10 Oe a gpa geeanh ee aes Bo ONC Ter WE try aaa? go For detailed methods of testing and analysis of turpentine the reader is referred to both of the above specifications. CHAPTER] XLX PINE OIL! ONE of the industries which has developed as a result of the policy of conservation in the United States is the manufacture of useful products from resinous woods. Enormous quantities of the latter, which in previous years were considered of little or no use and were deliber- ately burned in huge burners especially constructed for the purpose, or which were simply allowed to go to waste, are now being economically and profitably manipulated for the recovery of turpentine, pine oil, and rosin, or the production of tar oils, pine pitch, and charcoal. The two commercially important methods in vogue are, first, the steam and solvent or extraction process, and second, the destructive distillation process. H. T. Yaryan? has taken out letters patent on a process for extracting turpentine and rosin from resinous woods, which very well illustrates the extraction method as practised today. Resinous wood, reduced to fine chips by passing through a wood chipper, is charged into an iron vessel through a charging door at the top. The wood rests upon a false bottom over a coil supplied with superheated steam for producing and maintaining the 1 Journal of Society of Chemical Industry, June 15, 1914, No. II, Vol. xxxill, by Maximilian Toch. 2 The following is a list of the Yaryan U. S. Patents: No. 915,400, March 16, 1909 934,257, september 14, 1909 915,401, March 16, 1909 964,728, July 19, I9gI10 915,402, March 16, 1909 ~ 992,325, May 16, 1911 922,369, May 18, 1909 258 PINE OIL 250 proper temperature within the iron chamber. The door at the top and the discharge door at the bottom are closed, and the current of superheated steam is driven into the mass of chips. This is continued until the more volatile turpentine has been vaporized and driven over into the condensers. The wood in the extraction vessel is left charged with a small percentage of heavy turpen- tine, together with pine oil and rosin. Steam is shut off, the excess moisture in the hot wood is removed by connecting the vessel with a vacuum pump, and finally a liquid hydrocarbon (boiling point, 240°-270° F.) is sprayed over the top and allowed to percolate down through the pores of the wood. The resinous materials are thus thoroughly and completely extracted, and passed into a storage tank, from which they are pumped into a still used for separating the component parts of the solu- tion. From the still the hydrocarbon solvent is readily separated from the heavier pine oils by distillation under reduced pressure, on account of the great difference in the boiling point between the pine oils and the hydro- carbon solvent, the former boiling between 350° and 370° F. The pine oils are in turn separated from the rosin by distillation with superheated steam. Other so-called “low temperature” processes deserve mention as possessing features of merit, although sufficient data does not appear to be available to show their true value when operated on a large commercial scale. The Hough process, for example, is to be considered essentially a preliminary treatment in the manufacture of paper pulp from resinous woods. Chipped wood is placed in a retort and subjected to the action of a dilute alkali. The rosins are saponified and the soap separated from the alkaline liquor by cooling and increasing the alkali con- centration to the desired degree. The rosin soap may be 260 CHEMISTRY AND TECHNOLOGY OF PAINTS sold as such, or treated with acids for recovery of the rosin. The turpentine and pine oils are recovered either by preliminary treatment with steam or during the early stages of the cooking process. It will be noted that in the low temperature processes the only products recovered are turpentine, pine oils, and rosins, the first two removed by the action of steam, either saturated or superheated, and the latter by extrac- tion by use of a neutral volatile solvent or a saponifying agent. The so-called “spent wood” may be used either for the manufacture of paper pulp or as a fuel to generate the power necessary to carry out the process. In the destructive distillation process, the wood, in the form of cordwood 4 ft. to 6 ft. in length and 4 in. to 8 in. in diameter, is placed in a horizontal retort and the tem- perature gradually raised until the wood is thoroughly carbonized. The factor of greatest importance in the successful operation of this process is temperature control, as it is essential that the turpentines and pine oils be removed in so far as is possible before the temperature at which the rosins and wood fibre begin to decompose is reached. The total volume of distillate, as well as the percentage volume of each of the several fractions thereof, is largely dependent on the degree of temperature control. Destructive distillation of resinous wood was first carried out in earthen trenches, the combustion being controlled by partially covering the wood with earth. Tar and charcoal were the only products recovered. Then came the beehive oven, operated in much the same crude manner, but recovering the more volatile distillates, in addition to tar and charcoal. This was in turn super- seded by the horizontal retort, externally heated, hot gases being circulated either through an outer shell or through pipes within the retort. Next came the bath PINE OIL 26f process, wherein the cordwood was immersed in a bath of hot pitch or rosin, thereby volatilizing the turpentine and lighter pine oils and dissolving the heavier oils and rosins. After this preliminary treatment the bath was withdrawn and the wood subjected to straight destructive distillation. More recently! a retort has been devised utilizing the basic principle of the laboratory oil bath. The retort is heated by means of a layer of hot petroleum oil which is kept continually circulating between the retorts and an outer cylindrical shell that completely surrounds the re- tort proper. In this way it is claimed that the tempera- ture of distillation can be accurately controlled. The turpentine and pine oil obtained are fractionated and rectified by subsequent steam distillation. In running the retort the temperature of the oil bath is so regulated that the heat inside does not exceed 450° F. before all the turpentine and pine oil have been distilled. The products of destructive distillation by the several processes are in each case of very much the same general nature, namely, turpentine, pine oils, tar oils, pine tar, pitch, and charcoal. In some instances low-grade rosin oils are also produced. “Light wood” does not refer to woody fibre which has a low specific gravity. The name originated from the fact that this particular wood is so rich in oil and resinous material that it is readily used for lighting fires. In the southern portion of the United States little bundles of “light wood” are for sale in strips about % inch in diameter and 1 foot long. When a flame is applied to one of these strips of wood it becomes useful for lighting fires, hence the name “light wood.’ The author has seen “light wood” so rich in resins and oily material that by transmitted light a thin section looked like translucent 1 T. W. Pritchard, Journal of Society of Chemical Industry, 1912, 31, 418. 262 CHEMISTRY AND TECHNOLOGY OF PAINTS ruby glass. It is this particular wood which is most used for the distillation of wood turpentine, pine oil, and rosin. The product from that type of pine tree from which turpentine is obtained has always been regarded as pro- ducing two materials when the sap has been collected and distilled. The one material is turpentine, and the other rosin. About ten years ago, when destructive and steam distillation of pine wood became a practical industry, a third substance was recovered. ‘This material, intermediate be- tween turpentine and rosin, is now known as “pine oil.” As far as the author knows, no one has yet determined the chemical constitution of this intermediate product of the pine tree, which has been designated as ‘‘pine oil.” Two years ago the writer started this investigation, which is practically finished. There is as yet no standard of purity for pine oil, but that it has a definite chemical composition is now fairly well established. The only original investigation of the chemical composition of pine oil was carried out by Dr. J. E. Teeple! on long leat pine oil. Dr. Teeple says: ‘‘The commercial long leaf oil, as it comes on the market, is either clear and water white, containing 3 or 4 per cent of dissolved water, or it may have a very faint yellow color and be free from dissolved water. The specific gravity ranges from 0.935 to 0.947, depending on freedom from lower boiling terpenes. A good commercial product will begin distilling at about 206° to 210°, and 75 per cent of it will distill between the limits 211°-218° and 50 per cent of it between 213°-217°. A sample having a density of 0.945 at 15.5° showed a specific rotation of about [a] =* — 11°, and an index of 1 Journal of American Chemical Society, 1908, 30, 412; Journal of Society of Chemical Industry, 1908, 346. PINE OIL 263 refraction of Np 1.4830. In fractional distillation of the oil the specific gravity of the various distillates rises regularly with increasing temperature, becoming steady at about 0.947 at 217°. “Tf the oil consists essentially of terpineol, C,H,30, it should be easy to convert it into terpin hydrate, CyoH2oO2 + H.O, by the method of Tiemann and Schmidt. The conversion was found to proceed easily when the oil was treated with 5 per cent sulphuric acid, either with or without admixture with benzine. If agitated contin- uously, the reaction is complete within 3 or 4 days. If, on the other hand, the mixture is allowed to stand quietly, the formation of terpin hydrate extends over several months and produces most beautiful large crystals, which, without recrystallizing, melt at 117°-118°. When recrystallized from ethyl acetate they melt at 118°. The yield is about 60 per cent of the theoretical. This forms such a simple, cheap, and convenient method of making terpin hydrate that it will doubtless supersede the usual manufacture from turpentine, alcohol, and nitric acid, and instead of terpin hydrate serving as raw material for the manufacture of terpineol, as heretofore, the reverse will be the case.”’ The term “pine oil,” as now understood, is the heavy oil obtained from the fractionation of crude steam dis- tilled wood turpentine. When the sap of the pine tree is subjected to distillation in a current of steam the volatile liquid — turpentine — consists almost entirely of the hydrocarbon, pinene (CioHis). When, however, the trunk, stumps, and roots of the same tree have been allowed to remain on the ground for a number of years and are then steam distilled, there are obtained, in addition to the turpentine and rosin, certain heavier oils formed E Ber, 720; 171. 264 CHEMISTRY AND TECHNOLOGY OF PAINTS by hydrolysis and oxidation as a result of exposure to the atmosphere. To the heavier oils thus formed and yielded up in the process of steam distillation the term “pine oil”’ is properly applied. Pure pine oil has a very pleasant aromatic odor, similar at times to the oil of caraway seed or the oil of juniper seed. When pine oil is impure it is very difficult to use it for interior work on account of its pernicious odor of empyreumatic compounds. It has been used to a con- siderable extent for making paints which should dry without a gloss, and as a “‘flatting’’ material it has been very successful. It has the excellent cuality of flowing out well under the brush and of not showing brush marks, the latter because it evaporates so very slowly. It is a very powerful solvent, and many of the acid resins which have a tendency to separate when they are in- sufficiently heated with drying oils will remain together when pine oil is added. Pine oil can be used to a con- siderable extent as a diluent in nitrocellulose solutions, and as a cooling agent for the reduction of varnishes it also has excellent qualities. The author takes this opportunity of stating that on previous occasions his recommendations concerning new and useful materials for the paint and varnish industry have been misunderstood in some instances, and it is to be hoped that these re- marks will not be misinterpreted. Pine oil is a new and useful material, but it is by no means a substitute for linseed oil or turpentine or any of the other materials now on the market. It has properties peculiar to itself, and when intelligently used is of considerable value. Practically all the pine oil obtainable contains a small percentage of water in solution, to which it clings rather tenaciously, and it is by no means a simple matter to dehydrate this material. A rather complex apparatus for PINE OIL 265 dehydrating the material is necessary with temperature control, but the test which the author has devised for the determination of water is quite simple. If 5 c.c. of pine oil are mixed 9 with 1 c.c. of a neu- a tral mineral oil, like , benzine, kerosene, or benzol, and a_per- fectly. clear solution is obtained on shak- ing, no water is pres- ~ 4° ent; but ib there 1s +0 any water presentin a the pineoilthewater appears as a colloid, and a milky solution is obtained which does not’ separate after long standing. The fact that pine oil will take up a considerable quantity of water and still remain clear makes it useful for emulsion paints such as are very much in vogue at the present time for the interior of build- ings, and it has been suggested that the addition of water up to 5 per cent for such a purpose is beneficial on new walls. The United States Bureau of Chemistry! has developed a method for the determination of moisture by the use of calcium carbide; this is being investigated by the author but on account of its being a gas-volu- metric method it is not quite feasible for general use in technical laboratories. A number of commercial samples of pine oil were de- hydrated and analyzed. The tables following indicate the results obtained: — 1 U.S. Dept. Agriculture, Bureau of Chemistry, Circular 97. FRACTIONATION OF Pine O/L PER CENT. Oo ro) My S S < = » x fC) Lo ie: ¢ SS 200 210 220 DEGREES. -G. 880 S90 200/910) 9208 7950 240 No. 103. CHEMISTRY AND TECHNOLOGY OF PAINTS 266 ; : *sjro surd oy} Ul sotpindult 0} Ajqeqoid enp O[OI UL yor|q ysowye ‘Yep AIBA SeM anprsed ay} § pue F jo asvo a4} UT *3J9I SPM UISOI ated 07 gouvivodde ur Ieplus ‘onpisar pavy “][eUs & uoryeiodeas Jay (4) *(19}$9} ONGeI[seL) dno usdQ (2) +06 8°88 aes o'9V OS ote 1°36 gli ver Lz-o ayy 1978 €ge6'o 6 o'r6 o'F6 1°88 o'1g 0°39 v-ov 1°S6 ogt Levi ¢L°o IO][OD MVIIS oS£6"0 8 $°96 $96 $°28 Sol 6°8S S-6¢ * 9°g6 SLI gOc1 L1'0 aq 1978 z7Qe0'0 L S:S0 $-S6 0g 9°69 9°9$ gge L°z6 gol zeV1 olo IOJOI MVIIS cs¢6'o 9 2 rd ah ie eS Seg L-Sg grr 6O-eL1 6r'0 joquiv a[eq 16z6°0 $s Peat oe 2 3 c6 ogt S105 6S°o IOJOI MIS off6'0 v S°L6 S°L6 ook g°gS 6°9v bot ¢-L6 SvI beSzr IS°o ayy Jaye geeo'o € 1°26 26 gos gv Qe £07 £96 S4I V-gir 6z°0 ayy JoywM oynb JON Lzv6o-o Zz 1°96 1-96 z° LQ aos g cr g lz +°¢6 oLI S°-cv1 gg'0 MOT[OA ATUL YT €zvo-o I “siy ze “sry Vz “SIU Q “sy, 9 “sy V “sy Z ‘sty6 “J yutod anyea onyjea oy geo L er eee Joye (p) yseTq autpoy poy IoOjOD ye 13 “ds adits Jaye sso] ued Jog ssoy JUID Jog a “q 9$9 — eanjzeroduisy WOOT TV (q) yVeq wWrsys EOF SLSaL NOILVUOdVAY STIQ ANIC 10 SAaSATIVNY — ‘I aTav J, PINE OIL 267 TABLE IJ. — FRACTIONAL DISTILLATION OF COMMERCIAL PINE OIL Fraction Total Sp, er. Temperature in % distillate I 55 C. VTS Oe a las ae a re 2 2 0.882 eee T CA are ee ee. hs 5 afin Scape 5 7 0.920 Dae SOG ee he bec ap ewe eee II 18 0.933 eA AOE EM 8 cas wih Fn seh, bow Soe 10 28 0.939 Peer eye eS ay. 2 Aiea oe ee 25 53 0.941 ee ARR Raye, okie ses Nae os a5 88 0.942 ODE Dy oe 6 04 0.942 2 whe 9S a a ‘3 95 ae Ee i yy be acess oS 4 99 TABLE III. — ULTIMATE ANALYSIS OF PINE OIL Sample Number. C. H. O. Ceo Re SNS yee oe en 78.1 TT 35 10.4 B)o Ao te by cles ee AS a 77.0 11.4 10.7 eM a Pe oR a dic ste Bes 0 US as 77.0 TI51 11.9 MN Bs eh eyo eee PRY ER os 81.8 10.6 7.6 REE a on saree, die grey Re 80.9 10.6 8.5 le Sta SO a eee co nee aera 79.0 II.4 9.6 PSS RCO eI eg re ee 78.4 £572 10.4 oS Ewcigc gh 21h Sa eee eine are 79.6 rr-5 8.9 Oi es eo a 78.3 Liar 10.6 RA RT tA, Soe een ks Ya Pes 79.0 1i.2 9.8 Terpineol (theoretical)............... 77.85 ii 10.38 Preece LUIpentINe. 65. 2. a Fane de 87.7 11.9 American. turpentine... 6. ...5... 2.65. 87.7 42.1 Wicod tumpentine:. 0) 2 iF ia Coen 85.7 12.5 304 Pine vou, tirst-Funnings. 2... ee 84.3 11.8 3-9 Distillate pine oil, 174 — 195° C....... 82.6 11.4 6.0 CHAPTER XxX BENZINE THE petroleum products are used very largely in the manufacture of all kinds of mixed paints, the principal one used being that known as “benzine.”’ It belongs to the series of organic compounds having the general for- mula CnHo.+ 2. Although it is frequently added to paint in its pure form as a diluent it is just as frequently added in the form of a liquid drier which is a solution of the original thickened drier in benzine. Within the past ten years benzine has been so made that its odor is not very apparent, and there is much discussion as to whether benzine is a detriment to paint or hot. It is hardly necessary to touch upon the moral side of this question. If a man should order a paint made according to a given specification and free from benzine, or to contain only turpentine as a diluent, the addition of benzine would be a palpable fraud. It is, however, unnecessary to discuss this point. The prin- cipal questions for discussion are, first, ““Is a moderate amount of benzine harmful to paint?” Second, “How much benzine is permissible in paint?” Answering the second question first, as to how much benzine is permissible in paint, that depends entirely upon the paint. A thick, viscous, ropy paint which is so difficult to apply that it will not flow evenly is un- doubtedly improved by the addition of benzine. It would be just as much improved by the addition of turpentine; perhaps it would be improved most by the addition of 268 BENZINE 269 kerosene, especially in the case of very quick drying paints, since kerosene evaporates more slowly than either benzine or turpentine. In the case of such dilution theory fails and only practice can dictate how much diluent can be added. In the case of a dipping paint where the even spreading of a linseed oil paint is desirable, and the sudden evaporation of the solvent helps to produce a uniform coat, benzine cannot be replaced by any other solvent. | The argument that is held forth by many, that ben- zine is of no value in a structural iron paint for the reason that its rapidity of evaporation lowers the dew point, as then moisture is deposited as it evaporates, is a most fallacious argument, although in theory it is cor- rect. Turpentine will do exactly the same thing and so will any other solvent, depending entirely upon the hygroscopic condition of the atmosphere. If painting be done in an atmosphere where the humidity is high and the temperature near the dew point, it is always found that it makes very little difference what solvents are used, the condensation being apparent in any case. The metallic structure itself lowers the dew point so that the painting is being conducted on a film of invisible water, to the detriment of the paint and to the detriment of the metal. On the other hand a series of experi- ments made on this subject showed that where the dew point and the humidity are high, condensation easily occurs even though the percentage of moisture in the atmosphere is relatively small. (See ‘‘Causes of Rust in the Subway,” Journal of the Society of Chemical Indus- try, 1905, No. 10, Vol. 24.) A great advantage is to be obtained by the moderate use of benzine, for in brushing on a quick-drying paint containing benzine the evapora- tion carries with it much of the moisture in the paint. 270 CHEMISTRY AND TECHNOLOGY OF PAINTS The low price of benzine in America offers a great temptation for its unlimited use. In France and Ger- many, where the petroleum products are more expensive than they are in America, and more particularly in France, benzine is not regarded so much as an adulterant. However, the physical effects of benzine have been so thoroughly overcome since turpentine has reached such an abnormal price, that a number of most excellent brands have been placed on the market as substitutes, all of which are equal in physical characteristics to pure spirits of turpentine. The objection, of course, to kerosene as a diluent in paint is that it may carry a small percentage of paraffin oil that has a tendency to produce a “bloom” on paint and particularly on varnish. Quite a large number of petroleum products have been placed on the market which are so closely analogous to turpentine that were it not for the odor, or lack of odor, it would be very difficult to differentiate them. As an instance it may be cited that turpentine is a better solvent for some of the mixing varnishes and fossil and semi-fossil resin driers than benzine, but the newer petroleum or paraffin compounds, some of which have had marked success, are absolutely identical in solvent power, speed of evaporation, and viscosity, to turpentine, and while the polymerization acid test would clearly show that they are not turpentine, they can by no means be said to be inferior in working quality or solvent power to turpentine. The method by which these benzines are made consists in passing certain paraffin oils over red-hot coke in con- junction with wood turpentine. The product which is ~ obtained has little or no odor. /Thick or viscous paints, particularly the varnish and enamel paints, are so much improved by the addition of these materials that even an inexperienced painter will notice the free-flowing quali- BENZINE 271 ties of the material to which these diluents have been added. The petroleum products used in the manufacture of paint are principally 62° benzine, which means benzine having a specific gravity of 62° Baumé. Some of the other naphthas ranging from 71° to 88° are used, but these. are so light and bring so much higher prices than the 62° that they are not used as much as the 62° naph- tha.. The newer grades, however, which approach tur- pentine in physical characteristics, must be counted on as an important factor in paint on account of the extremely high price of turpentine, and the fact that it is strongly held in a few hands. On account of the decreasing amount of this product, substitutes must be recognized. After all, any solvent, whether it be benzine, turpentine, naphtha, benzol or acetone, is nothing but a solvent and evaporates completely, leaving the other vehicles to pro- tect the paint. Of course, too much solvent is a detri- ment to paint, no matter what kind it may be. SS a ae ee BENZINE ! Engler Distillation of Commercial 88° Naphtha Sicr, (Westphal) | ake. as. TeheOae (Gok wanna ee 0.651 IN Mao Wayne waubie Soar t ef 1.36095 : Temperature % Wt. SpeGrers..0..C. Na 50° 47.7 0.609 I. 3605 Oo atOr aS. 29.2 0.65 1.3756 Poel OO 6.8 0.70 I. 3930 Residue 1.4 1.4001 Engler Distillation of Commercial 62° Naphtha BDasUil- eG estohal lite wee ae oe TOU eet ae eee 0.732 NG Core oe etek Sika Oe hands 1.4106 1 Richardson & Mackenzie, Amer. J. of Sc. XXIX, May, 1g10. 272 CHEMISTRY AND TECHNOLOGY OF PAINTS Temperature % Wt. Sp: Grozo7200Gs Ni@s. oO 50 See Se SO stom st 1.2. oy) fe ene I. 3830 75° to 100° 20.0 0.7029 1. 3956 100 to 125° ees) 0.7286 1.4061 125° to 150° 24.6 0.7462 1.4168 Residue Oi: 2 5k Catan | ere ae 1.4282 WHITE SPIRIT In England and some parts of the continent of Europe, turpentine substitute is known under the name of “‘ White Spirit.” This name is, however, totally unknown in the United States, and while white spirit is a good turpentine substitute, it is not the same material as that sold in the United States. It has a very much more pungent odor and flashes at a lower degree. The United States Navy specifications demand a turpentine substitute with a flash at approximately 105° F. and white spirit used in Great Britain flashes at 75° F. White spirit is usually freed from grease or residual oil and distills over completely at from TOh tO 2O™ ae Much improvement has been made in the production of white spirit since the war, for some of the solvents which are sold in the British market of the type of white spirit are almost odorless. CHAPTER XXI TURPENTINE SUBSTITUTES ! WHEN coal is distilled in the dry form volatile hydro- carbon gases are liberated, which when condensed form a liquid which has great value in the arts, and is generally called crude benzol. Its composition really is about 60 per cent of benzol, the balance being toluol, xylol and solvent naphtha. The latter three are homologues of benzol. It is estimated that over forty million gallons of these solvents have been wasted in the United States in smoke and vapor in the manufacture of coke, but at this writing great efforts are being made to collect the vapors economically and to put in additional ovens for the manufacture of these by-products, so that it is very likeiy that both benzol and toluol will soon be sold again at normal prices. At this writing both benzol and toluol have risen from 25 and 30 cents per gallon to $1.25 and $7.00 per gallon respectively, owing to the great European war and to the small amount of benzol and toluol manu- factured in the United States. These materials have been sought for very eagerly for the manufacture of both ‘ carbolic and picric acids and trinitrotoluol. BENZOL This material was for many years known under the name of benzene, and here it must be noted that the benzene which is equivalent to benzol is always spelled 1 In the chapter on “Turpentine” the author has related how turpentine substitutes came into their own on account of the excessive price of turpentine. 273 274 CHEMISTRY AND TECHNOLOGY OF PAINTS benzene, and the light naphtha obtained from paraffin crude oil is spelled benzine. Benzol is the first volatile liquid which is recovered when coal tar is distilled. Benzol when pure is color- less. has a pleasant odor, a specific gravity of 0.879 and a boiling point of ro1° F. It flashes practically at air temperature. It crystallizes into a solid at the freezing point of water and has a peculiar analogy to water inasmuch as it melts again at about 37° F. It is insoluble in water but is soluble in alcohol, ether and petroleum naphtha. Its formula is CsHs; it attacks, though it does not dissolve, all forms of linoxyn, which it wrinkles and removes from the base. It is for this reason that it is so valuable as a paint remover. Benzol has remarkable solvent properties for many things which contain water, such as a number of the soaps, and is therefore invaluable to the paint manu- facturer when used in small quantities, for it prevents the livering or saponification of many of the paints which have alkaline tendencies, and which would become unfit for use if it were not for the small quantity of benzol added. The addition of benzol to mixed paints to be used for priming purposes has been found to be very advan- tageous, on account of the fact that a firmer bond is formed between a priming coat and the wood, so that when benzol is found in a mixed paint recommended for priming purposes it must be looked upon as a valuable ingredient. The addition of a very small percentage of benzol to mixed paints does no harm, but if a paint made with benzol and intended as a priming coat be used as a finishing coat it is quite likely to attack the ground coats and produce a shriveled effect. TURPENTINE SUBSTITUTES 275 The theoretical chemist will sometimes make a mistake when he finds benzol in a black mixed paint by reporting the presence of coal tar, from the false reasoning that if benzol is present coal tar must be present, because benzol is a constituent of coal tar. A chemist must, therefore, be very careful in drawing such a conclusion, for the presence of either coal or pine tar in a paint can be determined by other methods. TOLUOL Formula, CsH;:CHs3 Toluol is very closely related to benzol, has practically the same specific gravity but a trifle lower—.869 to .87 — a freezing point of 30° F., and a boiling point of 230°. It does not flash at air temperature, and therefore is of considerable value where high flash paints are wanted. In the manufacture of turpentine substitutes out of paraffin or petroleum naphthas the addition of toluol is of great value, particularly where refractory gums are to be dissolved. As for instance, cold petroleum naph- tha added to a manila varnish will practically throw it out or precipitate it out, whereas the addition of toluol prevents this, depending upon the amount of toluol that the solvent contains. It has been recommended, and from experiments made it appears to be a fact, that toluol added to a paint in a quantity not over to per cent is of great value in the painting of cypress wood, but it is doubtful whether it is any better than pine oil, which can be used more liberally and which has even more penetrative effects and a higher flash point than toluol. 276 CHEMISTRY AND TECHNOLOGY OF PAINTS XYLOL Formula, CsH4u(CHs)o Xylol really consists of three isomers having boiling points of 278° and 287° respectively. It cannot be very well separated by distillation. Xylol has all the char- acteristics of toluol but is not used to any great extent in the paint industry on account of its high price. SOLVENT NAPHTHA This is a mixture of different hydrocarbon compounds which have not yet been very well worked out; but sol- vent naphtha has a very disagreeable odor, which no one has been able to remove up to the present time, and therefore its use in the paint industry is very limited. When someone will discover a method for deodorizing solvent naphtha it probably will replace many of our solvents, as it is really a better solvent than anything we know of at present, and even dissolves such materials as gutta percha, balatta and many forms of rubber. Its specific gravity is the same as that of xylol and toluol, but it boils at a much higher temperature, depending upon its composition, from 300° F. to 360°. CHAPTER XXII CoBALT DRIERS! THE cobalt compounds which are generally offered on the market today may be divided into two classes. In the first are cobaltous oxid, acetate, sulphate, chloride, nitrate, hydroxid, and basic carbonate. In the second class are various grades and qualities of resinates (some- times called sylvinates), both fused and _ precipitated, oleates or linoleates, oleo-resinates, tungates and resino- tungates, besides some other liquid preparations com- posed in whole or part of the foregoing. From the varnish manufacturer’s standpoint the substances in the first division are crude materials which are utilized in the production of the compounds in the second class, and also in the preparation of some var- nishes, liquid driers, drying oils, and the so-called paint oils. The materials enumerated under the second class are the result of a varnish maker’s labor, and when properly made and used in mixtures to which they are adapted give very good results. The inorganic salts of cobalt do not directly come under the scope of this paper, and thus will not be directly considered except inasmuch as their use as crude material affects the driers into whose composition they enter: It is only within the past three years that the cobalt driers have been offered to the American paint and varnish 1 By V. P. Krauss, 8th Int. Congress of Applied Chem. From the laboratory of Toch Brothers, under the direction of the author. 277 278 CHEMISTRY AND TECHNOLOGY OF PAINTS manufacturers. Up to the present time their use is not general, first, because of the very high price, and second, because their use is not thoroughly understood. Many experimenters have had unsatisfactory results and there- fore refused to further consider the introduction of the new material. Furthermore, not all of the cobalt driers, whether liquid, paste, or solid, now offered for sale, are properly made and truly adapted to the pur- poses for which they are recommended. This situation, in addition to unsatisfactory results obtained by some of those experimenting, would naturally have a retarding effect on the introduction of a new type of material. The salts of cobalt which are at our disposal in com- mercial quantities are all of the cobaltous or divalent type. It has been found that although they can be readily used in the manufacture of driers and worked like the various compounds of manganese, lead, zinc, calcium, aluminium, etc., the organic compounds formed, which are the basis and active principles of the so-called driers, are not efficient while in the cobaltous state. The cobaltic combinations, however, are very active driers, and it is for the formation of trivalent cobalt compounds that we strive in the making of driers. This transformation can be effected in several ways. By blow- ing cold, heated, or ozonized air through the hot cobal- tous drier stock, or by the introduction of liquid or solid oxidizing agents. The use of cold or even heated air is a very long and tedious operation if carried out to the extent to which it is necessary in order to get the maxi- mum strength in the drier, and greatly adds to the cost of an already expensive material. The use of the liquid or solid oxidizers can be carried out successfully and in a comparatively short time, although even when great care is exercised the batch of material is in danger of catching fire. COBALT DRIERS 270 Since driers are used in a number of industries in which drying oils form part of the material produced, and since the operating methods of the various manu- facturers are widely divergent, the siccatives or driers adapted to each will in many instances show widely different characteristics, not merely in form but also in composition. Since the paint manufacturer and also the practical painter who mixes his own paints from paste colors and raw or treated oil are the principal consumers of what are generally known as driers, the materials adapted for their use may be first considered. The driers will, in practically all instances, be in the liquid state either very fluid, of heavy consistency or of a semi-paste nature. In composition, they will mostly consist of resinates, tungates, oleates, or linoleates, or combinations of the three. For the drying of linseed oil, when the proper driers are selected, little or nothing can be asked in ad- dition to those known at present. When the general lead, manganese and other prevalent metallic driers are well chosen raw linseed oil can without any difficulty be made to dry by the addition of from 5 to 10 per cent or even less, the time of drying under average weather conditions being from to to 24 hours. By the use of cobalt driers, the same drying effect can be obtained when only from 1 to 3 per cent of a liquid drier is used. The author is not yet prepared to say positively what the ultimate effect of cobalt driers is upon paint films, but from the experiments made it is deduced that cobalt has not the harmful progressive oxidizing action that some of the usual manganese-lead compounds have. It has also been noticed that although a cobalt drier may be fairly dark in color, it will not have as darkening an effect as one of the usual driers of like color would have upon a white paint. The cobalt driers 2890 CHEMISTRY AND TECHNOLOGY OF PAINTS likewise show the same phenomena as some of the others when used in excessive amount; that is, that although the paint film will set up well in the usual time the drying action apparently reverses and the film remains tacky. The terms applied to liquid driers are often uncer- tain and apt to be misleading. There are no general standards for strength or consistency, and, it must be admitted, many of the materials found on the market contain more volatile thinners than is conducive to obtaining a maximum drying effect with a minimum quantity of drier. The value of the cobalt specialties depends not on their power to dry linseed oil, but on their ability to make the lower priced semi-drying oils act like it. Soya, fish, and even corn and cottonseed oil are adaptable for use in paint, and when correctly treated, increase its durability. In the making of waterproof fabrics, insulating coat- ings, etc., both liquid and solid driers are used. In the linoleum, oilcloth, patent leather, artificial leather and similar industries, the semi-liquid, paste, and solid driers are in demand since for these products the manufactur- ers cook the oils and varnishes in their own factories. The paste and solid driers must essentially be con- sidered under the caption of crude materials because they must be churned or cooked in the oils or varnishes in which they are used. The methods of making both the solid and liquid driers are in general similar in the first stage of the process, and thus may be described under the same headings. Resinate of Cobalt; Precipitated and Fused. — This is correctly made by saponifying rosin or colophony with COBALT DRIERS 281 caustic soda or sodium carbonate, care being taken to avoid an excess of the reagent, and then precipitating with a solution of some salt of cobalt. The chloride or sulphate serve best for this purpose. The precipitated resinate, or as it is sometimes called, rosinate or sylvin- ate, must then be thoroughly washed, and then pressed and dried. ‘This will yield a pinkish, fairly fluffy powder when ground, which will readily dissolve in oil at a low temperature. The fused variety is made by melting the dried resinate in a kettle and then pouring into cooling pans. The operation is performed more rapidly by taking the cakes from the presses and driving off the water and fusing in one operation. Cobalt Oleates or Linoleates.—The basis of this class is generally lnseed oil, although walnut, perilla, soya, and some other oils may be used. The oil is thoroughly saponified with caustic soda, and, like the resinate, pre- cipitated with a salt of cobalt. The material is then carefully washed and pressed. It may be melted to form a dark viscous heavy fluid. Several samples of cobalt linoleate examined consisted of bodied linseed in which small amounts of inorganic cobalt salts had been dissolved. Another was of the same order with the addition of volatile solvents. True linoleate of cobalt, when fused with varnish gums and dissolved in volatile oils, yields an excellent drier. Oleo-resinates. — This type of drier is made by melting together the precipitated resinate and linoleate, some- times with the further addition of fused fossil gum- resins. Tungate of Cobalt. — Like the linoleates, the tungate of cobalt is made by saponifying pure China wood oil 282 CHEMISTRY AND “LECHNOLOGY OF srATN gS (tung oil) with caustic soda, care being taken to avoid excess of caustic, and then precipitating with a salt of cobalt. The tungate is then washed thoroughly, pressed and generally dried and fused. Great care is necessary in the preparation of a tungate since it oxidizes very rapidly, and the oxidized material is useless. Like the linoleate of cobalt, the tungate may be fused with the resinate to form what may be called a resino- tungate. In general the foregoing substances are incorporated in oils by means of heat, the combining temperature be- ing between 300° and 500° F. The amount necessary will vary from about $ per cent to 5 percent. In order to make liquid driers, the paste or solid driers can be melted alone or in combination with gum-resins, bodied linseed oil, or both, and then thinned to liquid consistency with volatile oils. Among other cobalt salts, some of the chemical manu- facturers offer the acetate, with directions for its use as a drier. All agree that between two and four tenths of 1 per cent are necessary to dry linseed oil. The oil should be at a temperature between 300° and 4oo° F., and be carefully stirred until all the salt is dissolved. Soya and China wood oil may be similarly manipulated. It is still a little too soon to make a positive state- ment as to how oils thus treated with the acetate with- stand wear and exposure. Cobalt oxide, like the acetate, can be directly added to oil during boiling. It, however, dissolves slowly and necessitates heating to high temperature; the resulting product is also very dark, and mostly consists only of bodied oil. Rosin also will directly combine with cobalt compounds on heating together in a suitable kettle or container. The product possesses a number of objec- COBALT DRIERS 283 tionable features. It still is mostly unchanged rosin, has become much darker and lost considerably in weight due to volatilization. The effect on oils of quite a number of cobalt compounds was tried, but none equal in efficiency to those described in the foregoing was found. One of the best methods for the manufacture of cobalt drier is to keep it im statu nascendi until it is ready for manipulation. This is best brought about by using ap- proximately the following formula. (1) 25 lb. caustic soda, 76° Bé (2) 20 gal. hot water (3) 20 gal. China wood oil (4) 5.5 lb. cobaltous nitrate or sulphate, concentrated solution. The caustic soda is dissolved in a varnish kettle in 20 gallons of hot water, and allowed to boil, then the China wood oil is stirred in slowly, and this forms a soap. To this must be added to gallons of hot water in order to make it perfectly fluid. In another kettle the cobalt nitrate and hot water are dissolved, and slowly poured into the China wood oil soap mixture and allowed to boil, adding water until 4o gallons of water have been slowly added. The cobalt soap is then a bluish crumbly mass which precipitates out and is strained and thrown into another varnish kettle, half full of boiling water. This ‘dissolves out all the sodium salts which are contained in the mass as a by-product and leaves the China wood oil cobalt soap. If this is filtered through two thicknesses of cheesecloth a cheese-like mass is obtained which should be rolled up into balls about the size of a fist, approximately r pound, and placed in a barrel half full of water. When ready for use, three of these balls may be added to 100 gallons of linseed oil or China wood oil as a drier, and if added in small pieces no excessive foaming will take place, 284 CHEMISTRY AND TECHNOLOGY OF PAINTS At temperatures over 200° C. this soap is taken up by the oil, and forms an excellent drier. In enamel paints of the long oil variety, particularly those that contain large quantities of zinc, 14 pounds of this soap to 100 gallons of oil will dry perilla oil or linseed oil at room temperature over night, but it has been found that this drier becomes less and less effective the older it becomes in the presence of zinc. It is therefore of advan- tage to keep it in its nascent condition in order that the best results may be obtained. For textile and special paint work more rapid drying is desired. The same formula can be used for making both lead and manganese soaps. It has been found where 50 per cent of cobalt drier is used and 25 per cent of lead and manganese added to the oil or varnish, excellent results are obtained. CHAPTER: XXIII COMBINING MEDIUMS AND WATER COMBINING MEDIUMS In certain classes of mixed paints, particularly house paints which are made of corroded lead, sublimed lead, barium sulphate, etc., there is a likelihood or tendency of the pigment to settle. This is more marked in the case of corroded lead than in any of the other pigments. To prevent this, In a measure, water is added, and up to a certain percentage (1 per cent) both the manufacturer and the consumer have accepted the fact that water is not injurious when added for the purpose of combining the paint; but beyond this percentage its effect is likely to be injurious. Sometimes for the sake of an argument, but more often for the sake of making a paint which contains no more water than the natural moisture of its constituents, a manufacturer feels the necessity of adding a combining medium other than water to prevent the paint from settling hard in the package. Among these are gutta- percha solutions, solutions of balata, para-rubber, gum chicle, etc. The rubber solutions mentioned serve their purpose very well without injuring the paint, and the percentage used is so small that it may be considered negligible. This, however, is not true of many of the mixing varnishes which are made by varnish manufactur- ers who have no experience in the manufacture of paint. They sell rosin yarnishes neutralized with lime, lead, or 285 286 CHEMISTRY AND TECHNOLOGY OF PAINTS manganese, and while they assist very well in combining the lead with the oil, the wearing quality of the paint is proportionately reduced. Within the last few years a new combining medium has appeared on the market which in itself is an improve- ment on all paints. It is made by melting a mixture of a resin (free from rosin or colophony) and heavy linseed oil, and reducing with China wood oil and naphtha. Where a manufacturer uses a combining medium of this character the paint becomes more viscous as it grows older, and when it dries it produces a satin-like gloss and shows fewer brush marks than a paint containing water. WATER IN THE COMPOSITION OF MIXED PAINTS The question of how much water shall be added to mixed paints, or how much water mixed paints shall contain, either added or incidental, is not fully decided upon, as there is a difference of opinion as to its value, and likewise a difference of opinion as to the amount necessary for certain purposes. There are some paints in which as high as 2 per cent of water is necessary, and in other paints less than 1 per cent is purposely added. That water is of great benefit in certain paints cannot be disputed, one large railway corporation permitting the addition of 1 per cent of water to its mixed and paste paints. A chemist in making an examination of a mixed paint must necessarily be careful in giving an opinion as to the amount of water in the paint, and great judgment must be used in a report. For instance, a paint, made accord- ing to a certain specification, containing a large mixture of Venetian red and yellow ochre, might contain very nearly 2 per cent of moisture, which was a part of the COMBINING MEDIUMS AND WATER 287 composition of the pigment. Then again, linseed oil fre- quently contains more than a trace of water, which the manufacturer cannot extract nor can he afford the time necessary to allow the water to settle out of the oil. A mixed paint should not contain over 1 per cent of water, for it is unnecessary to add more than this amount to any paint. The proper benefits derived from the addition of water to a pure linseed oil paint are suspension of the pigment and improvement in its working quality. Take the case of artists’ tube colors which lie on the dealers’ shelves for years and which are prone to get hard and likely to separate so completely that the color will be found on one side of the tube and the oil be entirely free on the other. Water is an absolute necessity in this case and is an improvement for both seller and user. The colors made with the correct addition of water are known fe ee and artists: prefer a color which “piles” properly. There are many ways of adding water to a paint. In some instances the required amount of water, together with the oil and the drier, are placed in a churn or mixer and the paste paint stirred in. Where materials like calcium sulphate, calcium carbonate, ochre, Venetian red, slicate of magnesia, silicate of alumina, white lead, etc., are used, there is no necessity for adding any combining material which will form a soap with the linseed oil, there being sufficient action between these materials and the water. It is an additional advantage that there is less likely to be complete saponification in a mixed paint to which no ‘‘emulsifier’”’ has been added. The following materials are used for emulsifying paints: 288 CHEMISTRY AND TECHNOLOGY OF PAINTS Saturated solutions of hypochlorite of lime. Five per cent solution of carbonate of soda. One-quarter of one per cent solution caustic soda. One per cent solution of carbonate of potash. Emulsion mixtures of half water and half pine oil. Solutions of hypochlorite of lime containing twenty per cent wood alcohol. Ten per cent solution of borax. Five per cent solution zinc sulphate. Seven per cent solution lead acetate. Five per cent solution manganese sulphate. Solutions of ordinary laundry soap or rosin soap in half alcohol and half water. Weak solutions of casein dissolved in ammonia water. Ordinary lime water emulsified with linseed oil. There is no license whatever for the addition of much water to paint. Some authorities state that as high as 15 per cent is permissible, but the author does not by any means subscribe to that, as 14 gallons of water in 100 gallons of paint are far in excess of any desirable amount. Three-quarters of 1 per cent or at most 1 per cent would probably be a maximum, and as an explanation of this it must be understood that materials like ochre, clay, silicate of magnesia, white lead, calcium sulphate and many of the pigments which contain moisture or water of crystallization may carry a small amount of water into paint. Yet there may be cases where water is permissible up to 5 per cent, but only for interior purposes. Flat wall paints which have a tendency to settle hard can be emulsified so as to prevent them from settling, and in a case of this kind where the wear of the paint is not taken into. consideration there may be some excuse or license for the addition of water. COMBINING MEDIUMS AND WATER 289 To detect water in paint, particularly in light-colored paints, is a comparatively simple matter. The method devised by the author is almost quantitative for some purposes. The first method ever published by the author consisted in placing a strip of gelatin in a mixed paint. When a measured or weighed amount of mixed paint was taken and the strip of gelatin allowed to remain immersed for twenty-four hours a fairly correct quantita- tive determination was obtained. Another method de- scribed some years ago involved the use of anhydrous sulphate of copper, a bluish white powder, which on the addition of water returns to the natural dark blue color of crystallized copper sulphate. The author has, however, devised the scheme of using a glass plate and mixing a paint with a dyestuff such as “Erythrosine B.”’ When about § gram of the dye and 5 grams of mixed paint are rubbed together with a palette knife on a sheet of glass, a paint con- taining no water will produce a distinct pearl-gray color; if there is water in the paint the mixture changes almost immediately to a brilliant cerise red, and if there is much water in the paint (over 2 per cent) the color changes into a crimson, so that the reaction is clearly marked. The test must not be allowed to stand more than four minutes, since even paints which contain no added water but which naturally contain traces of moisture will begin to change into a rosy color, in which the presence cannot be reported. In red, black or dark colored paints Ery- throsine B is just as indicative of water in paint, par- ticularly when the mixture is viewed by transmitted light. Even in the case of black paint the erythrosine emulsion paint will produce a beautiful purple color. 290 CHEMISTRY AND TECHNOLOGY OF PAINTS Emulsifiers have been used for hundreds of years, and it is well known that prior to the artistic work of the brothers Van Eyck, in the fourteenth and fifteenth cen- turies, mediums of egg and water to which oil was fre- quently added, were regularly used. Eliminating any discussion as to whether paint should contain water or not, if it be added it is best to use it with a harmless emulsifying agent such as pine oil. The addition of all of the metallic salts like silicate of soda, lead acetate, caustic soda, and the zinc salts is not to be recommended, because the resulting paint does not by any means give as satisfactory results as paint that contains no water. The use of oxidizing materials like hypochlorite of lime is never to be recommended, for, in case emulsion pamts containing oxidizing materials are used on steel, violent rusting will ensue. If water is to be used in some of the interior flat whites it has a distinctive value in the prevention of settling and the obliteration of brush marks, and for that pine oil is the best material. The only ma- chine necessary for the purpose is a rapid agitator, one that makes more than 50 revolutions per minute. A favorite formula is as follows: 100 lb. asbestine, whiting or clay 10 gal. water 5 gal. pine oil. The resulting semi-paste is used in the proportion of 2 gallons to 100 gallons of paint, thus making about 1 per cent water in the finished paint. In the textile industry, the favorite material used for emulsifying is casein which has been digested in ammonia water. One pound of casein, free from borax or phosphate of soda, is mixed with one gallon of 20° ammonia water, COMBINING MEDIUMS AND WATER 291 and allowed to stand over night. The next morning this will assume the condition of a glue solution. Fifty pounds of whiting, two gallons of oil and 1o gallons of water are mixed with this casein solution and heated until nearly all the ammonia is driven off. This is then rapidly agi- tated for one hour, and the mass is set aside and used as is necessary as an emulsifying agent. Ammonium tannate, clay, water and linseed oil is a harmless emulsifying formula and the ammonium oleates and ammonium stearates are also to be recommended, but where their use is beyond 5 per cent they are more than likely to produce flat effects. However, sometimes this is found desirable. CHAPTER XXIV FINE GRINDING THERE is a great difference of opinion on the question of how paints should be ground, and a careful canvas on this subject reveals the fact that most paint manu- -facturers believe that all paints’ should be very finely ground. This is a great error, for there are many con- ditions where a paint should be slightly coarse in order to give proper results, for if paints do not have a slight amount of coarseness, or ‘“‘tooth”’ as it is called, one coat will not hold successfully on the other, and it is for the very reason of producing a mechanical bond that fillers are used which have a distinct grain. Without making any general rule on the subject, all priming coats should have sufficient tooth to enable the succeeding coat to hold. Those familiar with the subject are aware of the fact that a gloss coat on a gloss coat very frequently peels, and the same is sometimes true of a gloss coat on a’ priming coat which is too finely ground. This does not apply to a finishing coat, because the finer a finishing coat the longer it lasts and the cleaner it remains, for a coarse finishing coat will hold dust and dirt which even a heavy rainstorm will not always dislodge, while a smooth, finely ground finishing coat acts like a glaze and remains clean until it perishes. It may therefore be taken as a general statement that priming coats should be slightly coarse and finishing coats should always be fine. 2092 FINE GRINDING 2093 If you take the case of the finishing of a very fine object like a piano or an automobile, rubbing varnishes are used on the undercoat, and these varnishes are scarified with pumice stone for two reasons: first, so as to smooth the coat thoroughly because the succeeding coat when applied will then itself produce a smooth and glossy effect, and secondly, so that the next coat which is applied can bind itself mechanically to the undercoat. If, therefore, rubbing is a practice where varnished objects are to be finished, it must be taken as a rule that where paints are applied and rubbing is not practiced a slight grain is of great benefit, so that the question of fine grinding does not apply to every case. CHAPTER XXV THE INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES ! Ir may properly be said that direct sunlight has a very destructive action on paint and varnish films, and the author had noted as far back as 15 years ago that many of the paint materials that were perfectly water- proof in places where sunlight never reached became permeable to water and disintegrated very rapidly when exposed to direct sunlight. As an example of this, it might be cited that pure asphaltum, when applied in a good continuous coat on cast iron pipes in a cellar, will last from three to four years, yet the same asphaltum when applied on the roof of a building will show al- most complete decomposition within 20 days. In order, therefore, to determine the cause, the first experiments with a series of bitumens were made as follows: Sheets of clean steel and wood were painted with a variety of bitumen compounds and exposed to direct sunlight under various colored glasses, finally reduced to the three colors, violet, green, and red; for obvious reasons these three served all purposes. It was found at the end of four weeks that the bitumens exposed under the blue rays showed marked signs of decomposition, those under the green showed some signs, and those under the red none whatever. The same experiments were tried again by cementing the glass to the painted surface, when little or no decomposition followed in any case. A large ! Reprinted from the Journal of the Society of Chemical Industry, April 15, 1908. No. 7, Vol. XX VII, Maximilian Toch. 204 INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 295 variety of experiments was then tried by mixing the bitumens with various pigments, and a preservative action was obtained in direct ratio to the pigment used, so much so that a sample of paint made to contain 80 per cent of bitumen, 15 per cent of linseed oil, and 5 per cent of finely divided carbon, showed only slight deterio- ration at the end of six months; this was easily accounted for by the fact that the finely divided carbon prevented the absorption of many actinic rays. While these experiments were very conclusive, it was necessary to determine the cause, and to this end a large variety of experiments was conducted, all of which were productive of excellent results. All asphaltums are bitumens, but all bitumens are not asphaltums, and it is necessary to look into the com- position of the asphaltums which decompose in the sun- light and of those resins which do not. The difference between a resin and an asphaltic bitumen may generally be stated as follows:— Asphaltums and bitumens are composed principally of carbon and hydrogen, whereas the resins are semi-fossilized, and composed of carbon, hydrogen, and oxygen. Asphaltums, whether they be natural or artificial, consist largely of hydrocarbons of the series of CaHon-2, CoHen—1, CoHon-s, etc., and according to Clifford Richardson! and others, these hydrocarbons are probably polymethylenes. From a large number of combustion determinations made with bitumens, it may be safely stated that many of the bitumens are probably polymethylenes of various series, as above. There are, of course, substances in bitumens such as sulphur and nitrogen, which probably exert very little influence on the material from an actinic point of view. Assuming, 1 See “The Modern Asphalt Pavement” and “Origin of Asphalt,” by Clifford Richardson. 206 CHEMISTRY AND TECHNOLOGY OF PAINTS therefore, that the hydrocarbons are of the character described, we -should have under the combined action of the oxygen of the air and the actinic rays of the light, sometimes, in conjunction with moisture, a favorable condition where oxygen would combine with hydrogen, and carbon be set free. Therefore, if this reaction takes place, all bitumens in a short time ought to become car- bonized and deposit relatively pure carbon on their sur- faces, and this is exactly what takes place, the action of the sunlight probably resulting in a combination of the _ hydrogen with oxygen, and a deposit of what appears to be carbon takes place. If this, then, is the first lucid explanation of the decomposition of bitumens in sunlight, it is the explanation of the cause of the valuelessness of pure bitumens as protective paints for exterior purposes. Even the addition of a small amount of bitumen to a large percentage of otherwise good paint will result in the decomposition of this paint when exposed to the direct action of moisture and light. We have no such action when materials are used which are glycerides of fatty acids, such as fish oil, Chinese wood oil, and linseed oil. Indeed, any one of these three oils are light-proof in a very large degree, and fish oil and Chinese wood oil are both heat-proof and light-proof. Linseed oil, however, unless prepared with fossil resins, is not water-proof, but fish oil is more water-proof, and Chinese wood oil most water-proof of all. At the same time, pure Chinese wood oil is less light-proof, next comes fish oil, while linseed oil is most light-proof, and there would appear to be an established ratio that a paint or varnish containing the least amount of oxygen is the least light-proof and the most water-proof, and the paint containing the largest amount of oxygen is most proof against light, and least water-proof. INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 297 In conclusion, and as evidence of the correctness of these statements, if a sheet of metal or wood be painted with asphaltum or bitumen-paint and exposed to sunlight and air, the coating will be rapidly decomposed, and after a lapse of 20 days probably carbon will be set free. At least, this is a deduction from the nature of the bitumens. Minute scrapings from the surface of exposed bitumens show that the principal constituent is carbon, and, whereas the original material contains much less, the exposed bitumen shows over 95 per cent of carbon, the remainder being principally hydrogen, with a small difference, which is evidently oxygen.’ This shows that the general reaction tends to produce carbon. The painting of concrete to preserve it against the action of moisture and frost is destined to become as large an industry as the painting of wood, and those who have tried asphaltum paints for this purpose have already found to their sorrow that disintegration takes place in a very short time, even though the material be perfectly proof against the alkaline action of the lime in the con- crete, and as linseed oil paint is rapidly destroyed by concrete itself, owing to the interaction of the lime and the linseed oil, we have to look for other materials with which we can coat concrete in order to preserve not only its appearance, but the very structure itself. - Regarding the action of sunlight on pigments, it is well known that lithopone is rapidly acted upon by light, and direct sunlight turns it a dark gray, but frequently overnight the color leaves it and it is brillant white again in the morning. English vermilion (mercuric sulphide) is also acted upon by sunlight, and forms first a brown compound and then a black compound of mer- cury. This has been regarded as mercurous sulphide or as a sub-sulphide of mercury, but on this question the 2098 CHEMISTRY AND TECHNOLOGY OF PAINTS writer has doubts. Some of the oxids of iron, par- ticularly the bright red ferric oxids, are affected by light, and a compound results which from bright red turns to brown, probably a change tending towards the formation of ferrous oxid. We know that a large number of the organic dyestuffs tend to bleach in the sunhght, but sunlight alone is never very active regarding the decomposition of colors when air is excluded, for even mercury vermillion is regarded as permanent when it is covered by a coat of varnish. This is largely true of the organic lakes and finer colors used for coach painting. Linseed oil itself is bleached by sunlight, but this is a chemical change produced by the actinic rays in which the green chloro- phyll is changed to pale yellow. The fading, darkening and discoloration of paints is a phenomenon not clouded in mystery as it formerly was. A pure bright ferric oxid, of the Indian red type, when applied either in the form of a shingle stain or in the form of a paint made with linseed oil, darkens considerably on exposure to sunlight. ‘This influence is more evident when linseed oil is used as a vehicle, but not marked when the China wood oil varnish is used. It is, therefore, reasonable to infer that the ferric oxid changes into a higher oxide and the higher oxids are not bright red, but brown. Red lead which should be an absolutely permanent | color to light, turns a grayish white on exposure, which is primarily due to the action of sulphuric and sulphurous acids in the air. It is really not a fading reaction but the formation of a microscopically encrusted salt on the surface, which masks the original color. Chrome greens of the reduced variety which are mix- tures of chrome yellow and prussian blue based upon fillers and reinforcing materials such as barytes, whiting, INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 299 calcium sulphate, etc., are never permanent when exposed, and invariably bleach. There are many instances where the color changes into an ochery olive color and whether this is a Brownian movement of the filler, or an action of sulphuric acid, has not yet been definitely determined. It may possibly be both, for it is a well known fact in portrait painting that a white underground eventually works its way partially to the surface, or near the surface, and no other explanation can be had of this excepting that it is a Brownian movement. Para and toluidine reds when reduced with whiting and barytes sometimes change within a year to a straw color, which is not due to any actual fading of the dye itself. The peculiar part of these changes is, and this applies also to the green pigments, that when the so-called faded suriace is rubbed or wiped with a rag dipped in linseed oil, the color comes back to its pristine brilliancy. On the other hand, when these reduced pigments, such as chrome green, para red and toluidine red, are coated with a China wood oil waterproof varnish shortly after they are thoroughly dry, the apparent fading or bleaching does not take place. It is, therefore, reasonable to infer that this type of fading is only a masking of the color, due most probably to both chemical influence and the Brownian movement of the filler. The decomposition of lake colors in sunlight is a differ- ent type of reaction and due entirely to the action of the rays of light from green to violet, and the direct actio1 of ultra-violet light. Carmine, for instance, even under glass will fade out completely in three months. The alizarin lakes in concentrated form will not be affected at all, but many of the other aniline dyes, such as the basic and the azo types, fade partially in three months and are therefore useless for the painting of automobiles, 300 CHEMISTRY AND TECHNOLOGY OF PAINTS railroad signals and sign work. Once the lake colors fade, it is not possible to bring them back to their original condition. It is possible to test colors for permanency to light by means of ultra-violet light in less than an hour. The iron arc and the carbon arc are also very effective, even though they be enclosed in glass, but it is always wise in making these tests to moisten the color with water as the reaction takes place much quicker in water than it does in a dry atmosphere. CHAPTER -XXVI PAINT VEHICLES AS PROTECTIVE.AGENTS AGAINST CORROSION ! A CAREFUL search of the literature of the past twenty years has failed to reveal anything like a systematic investigation of the relative value of different vehicles used in the manufacture of paints for structural steel and the prevention of corrosion. There are a few isolated cases in which boiled linseed oil,? Kauri linseed oil var- nish* and spar varnish as protective coatings on structural steel were studied. For many years past much has been written and many investigations have been made on the protective quality of the pigments, but no one has appar- ently made any study of the vehicles. It is quite obvious that without a vehicle a pigment is useless, and the author knows of no instance where a pig- ment could be used alone, with perhaps the single exception of Portland cement, if that may be classed as a pigment; even then, Portland cement would be useless unless water were used asa vehicle. The example need hardly be called to your attention of taking a dry pigment and using water as a vehicle to show you that when the water evaporated it| would leave the pigment, and the pigment in turn would leave the metal; and yet, to the best of the author’s 1 Journal of Society of Chemical Industry, June 15, 1915. No. 11, Vol. XXXIV, by Maximilian Toch. ooG Von Kreybig, Farben Ziz.,°17, 1766-8; “J..N- Friend, Carnegie Scholarship Report, Iron and Steel Inst., May, 1913, pp. 1-0. 3 Address of Prof. A. H. Sabin before American Society of Civil Engineers, Nov. 4, 1896, reported in Engineering News, July 28, 1808. 301 302 CHEMISTRY AND TECHNOLOGY OF PAINTS knowledge, nobody has paid any attention to the very im- portant réle that is played by the vehicle itself. There is an old proverb which says, ‘One hand is useless, for one hand washes the other,” and it seems that the same is true with reference to vehicle and pigment, for one is of little value without the other, and if any value is to be attached to either of them the vehicle has by far the advantage, because there are some vehicles which protect — for a considerable length of time. With this end in view exposure tests were made in 1913, in which fifty-two steel plates (in duplicate) were carefully: freed from grease by washing with benzol, dried, sanded, and rubbed clean with pumice, and then coated with all the paint vehicles or protective vehicles to the extent of fifty-two in number, many of which, of course, are seldom, if ever, used alone, and some of which are failures a short time after they are put on. _ However, the author wanted to do this thing thoroughly, and for this purpose selected the same quality of steel, known as cutlery steel, which has been used by him for many years for his exposure tests. It is a steel which rusts very rapidly. Those plates must be eliminated which have shown no rusting in the year and five months that they have been exposed. These were coated with the paraffin or machin- ery oil compounds, and it would be poor advice to any engineer to coat steel with paraffin compounds, for the method of cleaning before the application of any good paint would have to be very carefully followed out, since no protective paint would hold on steel that re- tained the least trace of a paraffin coat. Then the paraffin, or non-drying oils, all collect a great deal of dirt, which showed that this would have to be entirely removed before any paint could be applied. PROTECTIVE AGENTS AGAINST CORROSION 303 Plate No. 41 showed excellent results, and a material of this kind would not be so very expensive where en- gineers demand that steel be coated with a clear liquid in the shop so that the steel may be inspected in the field. This was composed of half spar varnish and half stand oil. Stand oil is practically a polymerized linseed oil. Linseed oil when heated to 550° F., with a drier like Japanner’s Prussian brown or borate of manganese will produce a very thick viscous liquid, which is largely used as a patent leather finish. This can be reduced with 50 per cent of thinner and still have the fluid- ity or viscosity of raw linseed oil, and is, therefore, inexpensive. | Plate No. 50 was coated with a material containing to per cent of paraffin oil, which might be classed as an adulterated linseed oil, and while it showed up very well, it could not be recommended because on an exposed structure like a bridge a coat of good protective paint would not adhere very thoroughly. Plate No. 52 has taught a valuable lesson with regard to the use of raw China wood oil which is heated to a suf- ficient degree of heat to take 10 per cent of a tungate drier, and then thinned with 15 per cent of benzine. This made a material which is hardly more expensive than good, boiled linseed oil, and left a most excellent surface for repainting. In fact, this has proved itself the equal of plates No. 22 and No. 23, with the addition of a better surface for repainting. Plate No. 46 was coated with kettle-boiled linseed oil, and is very good, but this material might be regarded by some engineers as too expensive for application, as it took all day to make this oil. A carefully selected linseed oil was chosen to start with, to which was added 5 per cent of litharge and no other drier. This oil dried 304 CHEMISTRY AND TECHNOLOGY OF PAINTS | very badly, but when it did dry produced a good flexible film which lasted. This must not be confounded with the average boiled linseed oil of commerce. The various coatings used in these exposure tests have been divided according to their protective value into five classes: t and 1 b— Those vehicles which have little or no value for the prevention of rusting. | (a) The raw and refined drying and semi-drying vegetable oils. (Plates Nos. 1, 7, 8, 13, 35, 30) 47) 400) (b) The same oils to which to per cent of drier had been added. ‘(Plates Nos. 2, 3, 4; 0,50) to.muaemuee 14, 34.) (c) The more or less volatile paint thinners. (Plates NoS.i17:718,-10, 207325) (d) Solutions of celluloid and pyroxylin. (Plates Nos. 24, 25.) (ec) The liquid (at room temp.) paraffin oils. (Plates Nos. 21, 30.) 2— Those vehicles which showed some degree of protection, though not very much at best. (a) Wood-oil varnishes containing a certain percentage of rosin. (Plates Nos. 26, 20.) (b) Copal-wood-oil varnishes. (Plates Nos. 27, 28.) (c) Varnishes made from linseed oil which had been thickened and oxidized by blowing with air, oxygen or ozonizediair.. (Plates (Noss32a 7) This compared with the results obtained below with cooked-oil varnishes proves conclusively that the film yielded by a blown oil is not nearly as waterproof and resistant to severe weather conditions as that formed by a boiled or polymerized oil. 3 — Varnishes or varnish mixtures which protected the steel very nicely as long as weather conditions were PROTECTIVE AGENTS AGAINST CORROSION 305 not severe and temperature changes not very rapid and pronounced. (Plates Nos. 39, 40, 42, 43, 44, 45, 49.) 4— The semi-solid and solid paraffin oils. These show a very high degree of protection from rusting. Pa teseNOS. £5. 31.) 5 — Those varnishes and vehicles which afford a high degree. of protection against .corrosion. To be set down in this class a material must be extremely water- proof; it must dry with a film which is very elastic and yet tough in order to be able to withstand “‘ weathering.”’ A film which cannot remain intact against condensed moisture, snow and ice and despite comparatively wide and sometimes rapid changes in temperature (as between day and night even in rather warm climates), will of necessity afford very little protection for the steel to which it is applied. As the table on pages 307-308 shows, this class comprises: (a) Spar varnish. (Plate No. 16.) (b) Varnishes made from linseed oil, or China wood oil, which have been thickened by a heat process. (Plates Nos. 22, 23, 52.) (c) Open kettle-boiled oil. (Plate No. 46.) In Plate No. 50 we find a rather anomalous case. It seems that raw linseed oil which has been dried with a small percentage of a liquid paraffin oil proved to be an excellent coating for rust prevention. The addition of any paraffin or non-drying oil, even in such a small quantity as is shown in Plate No. 50, is dangerous in case repainting becomes necessary. Al- though the matter is not settled in the author’s mind as to whether linseed oil and paraffin oil dissolve in each other, his idea at present is that, although they apparently make a clear solution, separation takes place. Several experi- ments were conducted, and it was found that a film of lin- 306 CHEMISTRY AND FECHNOLOGY OF PAINTS seed oil which contains paraffin oil in some quantities when apparently dry shows minute globules of paraffin oil in wet condition when the film is heated over 100°C. A film of linseed oil containing to per cent of paraffin oil after it is six months old can be extracted with naphtha and shows uncombined paraffin oil. These experiments prove conclusively that it is dangerous to mix a paraffin oil with linseed oil for any purpose, excepting where it is not necessary, or not the intention, to repaint subsequently. Note: All the photographs submitted (see pages 309- 310) were taken during December, 1914. oon, PROTECTIVE. 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ENGINEERS have commented publicly on the electro- lytic corrosion of structural steel, particularly those parts known as grillage beams, supporting columns and base posts, which are either in the ground or surrounded by concrete and partly above the ground, with a view of determining beyond question at which of the poles corro- sion occurs, and whether one pole is more active than the other. The author performed an experiment by taking two sheets of high grade watch spring steel, which is ex- tremely susceptible to corrosion, and connecting them with the ordinary bluestone telegraphic cell. Voltmeter and ammeter were placed in the circuit and the two pieces of steel buried up to 5 in. in sand. Careful observation was made every day to see that the current was uniform, and the sand was first moistened with salt water and then contin- ually moistened with distilled water so that the same strength of salt solution was maintained. This experi- ment was conducted for too days, and assuming that the current travels from plus to minus, or from anode to cathode, the anode being connected with the copper and the cathode being connected with the zinc, corrosion was noticed almost immediately at the anode, and the plates showed violent corrosion at the anode and practically no corrosion at the cathode. These plates indicated some 1 By Maximilian Toch. Reprinted from Proceedings of American Society for Testing Materials, Volume VI, 1906. 311 a2 CHEMISTRY AND TECHNOLOGY OF PAINTS slight corrosion on the cathode, which, however, was principally chemical corrosion. The strength of the current was .o5 of a volt and the distance between the plates, varying in the damp sand, was 15 inches, and the amperage varied from .o2 to .o5. The current was measured by a “Pignolet,” direct reading, continuous current volt-ammeter, and the amount of current which produced this corrosion was exceptionally small. Another experiment was tried exactly in the same manner, for a shorter period of time, but instead of using two plates, three plates were used, the third one being designated as the “free”? plate, in which chemical corro- sion had full sway. At the end of six days these plates were removed; the anode showed marked corrosion, the cathode plate showing practically no corrosion at all, and the ‘“‘free’ plate showed a fair average between the cathode and the anode, and it can be deduced that the difference between the cathode and the anode corrosion is equal to the “free” corrosion. In other words, there is many times more corrosion on the anode than there is on the “free” plate, and no corrosion on the cathode plate. The rust first produced was the green ferrous oxid, Fe(OH),, which, being a very unstable product, was quickly converted in the air into Fe,O;, N(H,0). The current was .1 of a volt and .1 of an ampere which produced this result. The salt solution was four times as strong as that produced in the first experiment. A third experiment was, however, of the greatest im- portance, owing to the fact that the author attempted to imitate the conditions exactly as they existed in buildings. The same kind of steel was taken and bedded in various mixtures of concrete, starting from neat PEeCLROLY TIC CORKOSION OF STRUCTURAL STEEL -°313 cement and going up to 1:3:5. There is a well-known law in physical chemistry that reactions which take place with an increase of pressure are retarded by an increase of pressure, and the question has come up as to whether it is possible for steel to corrode when surrounded by concrete, many engineers holding that the alkaline na- ture of the cement will prevent the corrosion, and others holding that in conjunction with this condition the pres- sure exerted by the concrete prevents chemical decom- position. The author is glad to be able to throw some light on this subject, and the following experiment was carried out: In the first place cement was taken of known com- position, agreeing practically with the definition as quoted in the Journal of the American Chemical Society, July, 1903, when the question of the permanent protection of iron and steel by means of cement was thoroughly gone into. The cement for these experiments was what might be termed the tri-calcic silicate and calcium aluminate. This is in contradistinction to the general classes of Portland cements containing dicalcium ferrite as a part of their composition and free calcium sulphate in excess. A cement of the calcium aluminate class, free from iron and free from calcium sulphate, is a well-known protector of steel and iron against corrosion, and this class of cement was used in these experiments. The pieces of steel were connected up with six elementary cells of sufficiently high voltage and amperage, and it was impossible to get a direct reading from the volt-ammeter, the instrument being too sensitive. The seven parts of cement containing the steel strips were then put into the circuit and wet every few hours with solutions of 5 per cent sodium chloride and 1 per cent nitric acid, and water, in order to increase their conductivity and produce corro- 314 CHEMISTRY AND TECHNOLOGY OF PAINTS sion as rapidly as possible. The average strength of the current was .o5 volts and .o5 amperes throughout the entire experiment. Corrosion was immediately noticed at the anode pole, and the pat of neat cement, which should have protected the steel most perfectly against all kinds of corro- sion, showed a hair line split colored with rust at the end of the third day, which demonstrated that the chemical reaction of rusting had taken place at the anode; that the molecular increase had likewise taken place, and the pres- sure caused by the molecular increase had split the block. The steel in each alternate pat was painted half the length which was embedded in the cement with an insulating paint of known composition having a voltage resistance of 625 volts per millimeter. The results obtained after these various briquettes were broken open demonstrated that electrolytic corrosion takes place most violently at the anode unless the steel be coated with an insulating medium. Cement, concrete, or even neat cement, is therefore no protection against electrolytic corrosion, unless the steel be insulated as heretofore mentioned, and there was absolutely no corrosion where coated with insulating material. It must be noted that the cathode in all these experiments was perfectly free from any signs of oxidation. The result of this entire series of experiments is to prove conclusively that electrolytic corrosion of struc- tural steel embedded in concrete or sand takes place only at the anode and there with great violence; and further- more, that the cathode is protected by the electrical cur- rent. The popular impression that cement is a protector against all kinds of corrosion is fallacious. The anode does not only rust very violently, but a molecular in- crease of volume may take place which will split the con- crete shell. ELECTROLYTIC CORROSION OF STRUCTURAL STEEL aus Another conclusion arrived at is that the electrolytic rusting of grillage beams of buildings need not be feared if the structural steel be protected by a good insulating material, but the insulating medium should form a bond with concrete. CORROSION OF STEEL IN CONCRETE ! When steel corrodes its volume increases in relation to its molecular weight, and this is as 112 is to 214. This, of course, varies with the nature of the corrosion, and I am taking yellow rust as a standard. The increase in its vol- ume produces pressure, and if there is sufficient pressure to counteract the increase, there can be no corrosion, on the well known chemical theory that reactions which produce pressure are retarded by pressure. Tradition has taught us that concrete prevents corrosion of steel, and progress is retarded on account of tradition in many instances. If a steel bar is imbedded in concrete sufficiently deep and kept back from the exterior face sufficiently far so that the weight of the concrete is greater than the pressure pro- _ duced by corrosion, there will be no corrosion, but if the bar is near the surface so that water and air can reach the steel and react, you not only have corrosion, but the pres- sure produced by it splits off the surface of the concrete. The general statement, that concrete prevents corrosion is not correct, in fact, concrete may accelerate cor- rosion if the amount of lime liberated is below a given 1 Extract from a lecture delivered before the Concrete Institute, Chicago, February 25, 1925. 316 CHEMISTRY AND TECHNOLOGY OF PAINTS strength.! Take the case of a steel drum in which ammonia is shipped. Just as long as the ammonia is of sufficient strength no corrosion takes place on the inside of the drum because the alkali inhibits it, but empty the drum and fill it with water, or reduce the ammonia below a given strength, and you produce corrosion even though the liquid is strongly alkaline... If you take Portland cement, and mix it with two parts of sand, and then imbed a piece of bright, clean steel in it, one quarter of an inch below the surface, you can submerge this experiment in all kinds of corrosive liquids, and no corrosion of the steel takes place for two reasons, first, because a 1-2 mixture sufficiently trowelled is imper- meable, and secondly, because the amount of alkali gene- rated by a rich mixture of that kind is sufficiently great to prevent corrosion; but if you take a steel bar imbedded in a I-25-5 mixture you will have corrosion, or you will pre- vent corrosion depending upon the distance that the steel is from the surface. Every engineer, of course, understands that there are two elements that produce rust; one is air (oxygen), and the other is water, but pure air that contains no water is non- corrosive, and distilled water or boiled water that contains no air is non-corrosive. A piece of steel exposed to the air of New Mexico or Arizona remains bright for many months because the air does not contain sufficient moisture to pro- duce rust. I believe engineers will agree with me, that the proper place for reinforcing rods or bars to obtain the greatest compressive strength should be near the surface. Unless the surface be waterproofed, or the bars treated so that they will not corrode, the same effect will be produced as is shown in photographs 1, 2 and 3. If cement wash, as an exterior finish, is an added Bree ' Gorrosion of Iron & Steel; dilute Alkaline Solutions; J. Newton Friend; See also — Heyn & Bauer; Cribb & Arnauld. BLECTROLYTIC CORROSION OF STRUCTURAL STEEL sy tion on a concrete building, how much more of an added protection would an acid resin paint be with a waterproof coating; but the only trouble with a cement wash is, that it may or may not set, and if it does not, you will simply have a coating of dust. It costs very little to paint steel reinforcing rods, but an alkali-proof paint which adheres to concrete should be used; but where an engineer has any objection to the use of a pro- prietary material, he can get good results by making a mixture of one part of Portland cement, and one part of very fine sand, mixed to a creamy consistency with lime water. This will assure sufficient alkali to inhibit corrosion. There are in addition to the yellow rust, two other types of rust. The black and the brown, both of which are mag- netic (yellow rust is not magnetic), and frequently these peculiar brown and black scales dispersed with some of the yellow rust, will form layers, often 1/2’’ thick, and event- ually scale and drop off. There are many examples of this, particularly in subterraneous buildings and this reaction has been noted even in concrete where the concrete was par- ticularly lean and porous. Where there is a surface flow against concrete, the cem- entitious lime is leached out in time. The solvent action of sea water is much greater than that of pure water, as is evidenced by the experiment that 1-7/1o pounds of lime are soluble in 1000 pounds of pure water, and that 2-8/10 pounds of lime are soluble in tooo pounds of salt water. Many abstruse and complex theories have been advanced on the erosion of concrete in sea water, but it is most likely that this simple explanation of solubilities covers the case. A method for the prevention of corrosion of steel and concrete is to apply a proper coating on the exterior of concrete and prevent the access of air and water. Such a coating must, of course, be light-proof and should not be 318 CHEMISTRY AND TECHNOLOGY OF PAINTS neutral, but may be composed of a paint containing a resinous acid, which will combine with the free lime. Another method has been proposed which while fairly good, is always empirical, that is, the spraying of the sur- face before painting with either zinc sulphate or zinc chlor- ide. The action of zinc chloride seems to have the advantage of being slower, because it is a more deliquescent salt, but the objection to both of these compounds is that one never knows how much to use because the amount to be used is dependent upon the amount of free lime present and any excess is likely to destroy the paint film applied afterwards. Straight linseed oil paints are never good on raw concrete, and when a zinc salt is used in proper proportions, it will give effective service, particularly if spar vanish is added to the linseed oil paint. Perhaps the least harmful of any of the coatings for the preparation of concrete walls or sur- faces is a mixture of fluosilicate of zinc and sodium, or magnesium, and the most simple test of determining whether a wall will take paint without the decomposition of the oil, is to apply a test strip of diluted prussian blue, and if the blue turns brown in spots or entirely, it shows that the wall is still alkaline, but if the blue remains in its original con- dition, it shows the wall is neutral, and ready for paint. CHAPTER XXVIII PAINTERS’ HYGIENE ALL paints should be regarded as poisonous, and even though it may be understood as a general rule that materials like ultramarine blue are non-toxic or that silica has no effect upon the system, it is unwise for the paint manufacturer to permit his men either to breathe these in dry dust form or to allow his workmen to eat their meals before washing themselves thoroughly. We are all very familiar with the fact that white lead pro- duces lead poisoning, but in any well-regulated factory there is no excuse for this, and the amount of lead poisoning produced in factories like the large lead manu- factories in the United States is reduced to a minimum because the workmen are looked after most thoroughly. Workmen who are employed in a dusty atmosphere should always wear respirators, and workmen who work with lead products should not be permitted to grow mous- taches, as the dust of many of the poisonous pigments settles in the moustache and is then absorbed through the nose. White lead under the finger nails is absorbed into the system, and a careful watch of these things will prevent any disease among the men; but all in all there is more sensationalism and hysteria on this subject than is warranted by the results, for in paint factories where sufficient care is taken there is practically no illness among the men. 319 320 CHEMISTRY AND TECHNOLOGY OF PAINTS Paint vapors are all toxic, and any painter who is ignorant enough to apply any paint material in a closed room does not deserve to be a painter. Even materials like pure spirits of turpentine, which are known to have medicinal qualities, when breathed in large quantities are supposed to produce headache and vertigo, and the fumes of benzol, benzine and alcohol give the same results; therefore all people who apply paint should do so in well- ventilated rooms. Large vats which are varnished on the interior like brewers’ vats, or water tanks which are painted on the inside, are generally ventilated by the engineers in charge by having fresh air pumped in con- tinually to the men from the top and by simply pumping out the vapors from below, as practically all of the materials used in the manufacture of paint give off vapors which are heavier than air. Paint vapors are also inflammable, and any fire resulting from careless smoking or throwing lighted matches near paint is likely to produce disastrous results, but much information has been disseminated on this subject, particularly through the railroads, who now demand caution labels printed on each package before it is shipped with the result that many lawsuits which were instituted formerly against the manufacturer are not permitted today. The same is true with regard to the vapors arising from paint. It has been a practice among certain questionable lawyers to institute suits against paint manufacturers for illness, headaches, nausea, vertigo and such other physical ills as have resulted from the fumes of paint, and few of these lawsuits have ever been tried, because the paint manufacturer in former times has been inclined to settle a suit of this kind rather than go to court, but these cases are not as frequent as they formerly were on account of the wide- PAINTERS’ HYGIENE cre! spread knowledge of the subject. Fumes arising from paint are not dangerous in the open air, but if a painter is careless in a closed room it is certainly his fault, and a man who knows so little about paint should not be per- mitted to use it. CHAPTER XXIX THE GROWTH OF FUNGI ON PAINT FUNGI must not be confounded with bacteria. Bac- teria are invisible micro-organisms, and whether they thrive on paints has never yet been established. Their existence in oil or paint media has never been proved. No. 106. GREEN FUNGUS X500. Experiments made by the author in which various bacteria were grown in gclatin or agar agar have demonstrated that when turpentine, benzine, linseed oil, varnish or paints of any character, excepting those containing water, were added, they rapidly per- ished. Fungi, however, are totally different organisms. A fungus is derived from a spore which floats in the air and which practically is a microscopic seed. When this falls on fertile ground it sprouts and becomes a white downy mass, which is known as the hypha. This downy mass later on assumes a color, which may be either gray, green, yellow or black, and is known under the popular title of mildew, which is in reality a fungus or micro-organic growth of the vegetable type. What may be poisonous to a human being is evi- dently non-poisonous or neutral to a fungus, for fungi 322 THE GROWTH OF FUNGI ON PAINT. 323 can grow and do grow on practically all of the barium precipitates, which are known to be highly poisonous. A fungus needs both warmth and moisture for its propagation, and so we will frequently find that on the south side of a house at the seashore, where moisture will collect and the temperature will be fairly uniform, fungi wll sprout on a painted surface and frequently destroy the paint. This is more noticeable in the tropics than it No. 108. ASPERGILLUS NIGER — Photomicrograph xXt1o00, old fungus found on paint. No. 107. BLACK FUNGUS X125. is in the North, and more noticeable in the European countries than it is in America, for the humidity in the United States is way below normal for more than half of the year whereas the humidity is fairly constant in Europe and in the tropics. Some of these fungi are very disagreeable, particularly the black types, which will grow on the interior of houses, and which always propa- gate better in a cellar than they doin a garret, for light has a tendency to kill them. The fungi that are found on paint may be classified into the following varieties: 324 CHEMISTRY AND TECHNOLOGY OF PAINTS t. Penicilium Crustaceum types, of which there are many varieties, but all of which are greenish or olive grayish. 2. Aspergillus Niger, which is distinctly black and very tenacious. 3. Rhizopus Nigricans, which is brown and black, and which appears gener- ally in the Fall of the year. 4. Aspergillus Flavus, which is yellow and orange, and which grows freely on a putrid soil or near de- caying vegetable matter. It must be generally understood that the use fungicides is not always to be recommended, for ASPERGILLUS FLAvVUS— No. Ifo. Photomicrograph X600, yellow fungus frequently found in brew- eries and dairies, thriving on paint. No. 109. ASPERGILLUS NIGER — Photo- micrograph xt1o0o, black fungus fre- quently found on paint in cellars. of in breweries, malt houses, rooms which have swim- ming pools, and_ cellars which have been used for storage, these fungi grow at times, and it seems as if there is nothing which kills them. The best way to get rid ofsthem isero wash the surface copiously with soap and water and then spray a mixture of car- bolic acid and formaldehyde and afterward bichloride of mercury, but a man apply- ing a material of this kind must use a mask and a respirator. THE GROWTH OF FUNGI ON PAINT 325 Many a complaint has reached a paint manufacturer that his paint has turned black in spots under the eaves of a roof or in a ground- floor room, and the manu- facturer on account of ignorance has supplied fresh paint free of charge, or the painter has done the work over again, when Beearmatter of fact. the fault was due entirely to fungus growth. It is well, therefore, for the paint chemist to familiarize him- No. 111. Craposporrum Hersarum — self with at least these Photomicrograph x6co, a pale fungus few fungi, as they are the ”" Oe principal types which flourish on paint. For the prevention of fungus on paint, all the zinc salts and all the zinc pigments are excellent. A one per cent solution of bichloride of mercury can also be recom- mended where its poisonous effect has no influence. Copper salts, particularly the cupric salts, are all fungus preventives and fungicides, and in a damp dark cellar where white- wash, kalsomine, or linseed oil paint, or paint of any description is used, a spray of lime copper solution usually prevents the formation of fungus. Carbolic acid, in fact, all the phenols and all the cresols are much weaker in their fungicide property than copper, mercury and zinc salts. Bordeaux Solution is an excellent primer on cellar walls. CHAPTER XXX PHYSICAL EXAMINATION AND TESTING OF PIGMENTS Many methods have been described for the routine testing of dry colors by comparison with standards and the methods given here are the best and most approved for practical use, taking into consideration simplicity, speed, uniformity and accuracy of results. STANDARDS A set of all the pigments used should be kept in tightly © covered four-ounce bottles of the “‘shellac”’ type, preferably of amber glass, and arranged in order on shelves con- veniently near the slab and balance. If larger quantities are found advisable, they should be stored away elsewhere in cans. The standards, selected according to the requirements of the consumer, should not be made excessively difficult to match without considering the general conditions of their sources of supply and availability, as ideal colors are impossible to obtain at all times. New standards must be adopted from time to time as conditions change. REQUIREMENTS OF PIGMENTS The principal requirements of a paint pigment are purity of tone, tinctorial power (strength), smoothness and uniformity of texture, permanence to light, age and other extraneous conditions, opacity, and compatibility with the vehicles and other pigments with which it is to 326 PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 3 27 be mixed. Other characteristics are often desirable in dry colors for use in other industries, for example, opacity is desirable in a paint color, but transparency is often wanted in such uses as printing inks, stains and crayons. SHADE AND STRENGTH RUB-OUTS Shade. — A weighed amount of the standard is placed on a level slab of heavy plate glass or white marble and sufficient pale linseed oil is added to produce a stiff paste when rubbed with a flexible steel spatula or palette knife. The oil is added by means of a dropper or dropping bottle and the number of drops carefully noted. Care is taken to gather the pigment neatly, occupying a small area of the slab and rubbing not more than is necessary to pro- duce a uniform paste. The paste is then rubbed with a glass muller using a uniform slight pressure and a_ back-and-forth, slightly circular motion, the idea being to grind over the entire amount of paste with each complete rub. After 25 rubs the paste is gathered in a pile and given 25 more rubs. The procedure is then repeated using the sample to be tested, the same amount of oil is added regardless of the consistency of the resulting paste and the two rub-outs are spread on a strip of glass side by side, their edges just touching each other. . Pure white glass of uniform thick- ness 1s used, generally microscope slides or cleaned photo- graphic plates, and the comparison is viewed by daylight, artificial light including the so-called daylight lamps being usually unsatisfactory. For the routine testing of many pigments mulling is unnecessary and a thorough rubbing with the spatula will suffice, but a large number of them, notably red lakes and chrome greens, show a marked difference when rubbed unequally. When a pigment is 228 CHEMISTRY AND TECHNOLOGY OF PAINTS to be used in water, varnish or other medium it is often rubbed out in it instead of linseed oil. Strength. —o.1t gm. of the color is rubbed out with 2 gm. of French process zinc oxid, a standard can of which is kept on hand for the purpose. A measured amount of oil is used as described above. For prussian blues, ultra- marine and the blacks, the zinc is added in the proportion of 50 to 1 and for whites and pale yellows a standard prussian blue is used in the same proportion. The above figures are merely given as a guide and are usually varied according to the user’s preference or the strength of his standards. The reduction, however, should be enough to disclose all the tone qualities and allow slight differences in strength to be magnified enough to make them easily perceptible without reducing the standard to such a pale tint that weaker colors will show up too pale to get an idea of relative strengths. Strength rub-outs are always mulled carefully and if there is any streaking they are given additional mulling until the mixture is homogeneous and the color fully developed. TEXTURE, UNIFORMITY AND PURITY The simplest method of getting comparisons with standards for these properties and the one to which most of the published accounts seem to give the least attention, is microscopic examination. A microscopic view of the sample and the standard simply rubbed on halves of the same slide with a little water or alcohol will disclose more than many of the intricate methods sometimes used. With a little experience the appearance of the inert fillers such as asbestine, barytes, silica, etc. may be made familiar and the presence of their crystals in colors immediately PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 329 - recognized. For the examination of the inerts themselves the microscope is invaluable. In the case of the earth colors and some of the coarser artificial mineral colors a sufficient difference of texture will be apparent by the degree of grittiness under the palette knife. CHAPTER XXXII ANALYSIS OF PAINT MATERIALS ANALYSIS OF WHITE LEAD Gravimetric Methods — Estimation as PbSO, Lead. — Dissolve 1 g. in dilute acetic acid, filter, wash and weigh the insoluble residue. ‘To the filtrate add to c.c. of dilute sulphuric acid (1:1) and evaporate on the steam bath. Allow to cool, dilute cautiously to 100 C.c., add to c.c. of alcohol and stir well. Filter on a Gooch or alundum crucible, wash with water containing 1 per cent of sulphuric acid and to per cent of alcohol, and finally with alcohol alone. Dry at 110° C. Lead sulphate is appreciably soluble in concentrated sulphuric acid and slightly soluble in water. It is practi- cally insoluble, however, in 1 per cent sulphuric acid and in alcohol. It is very soluble in hot, concentrated am- monium acetate solution. Estimation as PbCrQO, Treat 1 g. in a beaker with hot water and just suf- ficient acetic acid to dissolve the white lead, using no more than 5 c.c. of acetic acid in excess. Filter off from the insoluble residue. Dilute to too c.c., heat to boiling and add an excess of a neutral, saturated solution of potassium dichromate solution. Allow to cool. Filter on a Gooch or alundum crucible, wash and dry at 130° C. Volumetric Methods — Estimation as Molybdate Dissolve 0.5 g. of white lead in 5 c.c. of concentrated hydrochloric acid by boiling. Add 25 c.c. of cold water 330 ANALYSIS OF PAINT MATERIALS 331 and proceed as indicated below, under “Standardization of Ammonium Molybdate.” Lead is precipitated as PbMoO, by a standard solu- tion of ammonium molybdate from hot solutions slightly acid with acetic acid. The solutions required are: (a) Ammonium molybdate — Dissolve 4.25 g. in 1 litre of water (b) Tannic acid solution — Dissolve o.1 g. in 20 c.c. of water Standardization of Ammonium Molybdate. — Weigh off about o.2 g. pure lead foil in a small Erlenmeyer flask and dissolve in 6 c.c. of nitric acid (1:2). Evaporate the solution just to dryness. Treat the residue with 30 c.c. of water and 5 c.c. of concentrated sulphuric acid and shake well. The precipitated lead sulphate is allowed to settle, filtered and washed with dilute sulphuric acid (1:10). Filter and precipitate are placed in an Erlen- meyer flask and boiled with to c.c. of concentrated hydrochloric acid until completely disintegrated. Then add 15 c.c. more of concentrated hydrochloric acid, 25 c.c. of cold water and neutralize with ammonia until slightly alkaline to litmus paper. Reacidify with acetic acid. Dilute to 200 c.c. with hot water and heat to boiling. Titrate, using the tannic acid solution as outside indicator, until a brown or yellow coloration is obtained with the latter. Precautions. — Titration must be carried out hot, at about 90° C. If the solution should cool down in the course of titration, reheat it. Here, as in the case of the titration of zinc with potassium ferrocyanide, the scheme of dividing the solution into two unequal parts may be used. To determine the excess of ammonium molybdate necessary to affect the indicator, place in an Erlenmeyer flask 25 c.c. of hydrochloric acid, neutralize until slightly alkaline to litmus, then reacidify with acetic acid. Dilute 332 CHEMISTRY -AND TECHNOLOGY OF PAINES. to 200 c.c., heat to boiling, and add ammonium molybdate drop by drop until the outside indicator is affected. Antimony and bismuth do not affect the results obtained by this method. Barium and strontium give very low results, while calcium yields but slightly low results. The alkaline earth sulphates tend to retard the solution of the lead. This difficulty can be overcome by thoroughly washing the lead sulphate and then boiling it with sufficient ammonium acetate. Carbon Dioxid and Combined Water. —t1 g. of white lead is weighed off in a porcelain boat. The latter is then placed in a combustion tube and heated in a current of dry air free from carbon dioxid. The water is col- lected in calcium chloride tubes, and the carbon dioxid in potash bulbs or soda lime tubes. Carbon dioxid may be determined by evolution by treating white lead with dilute nitric acid. Use a reflux condenser in connection with the evolution flask and dry the carbon dioxid by passing through calcium chloride before absorbing in the potash bulbs or soda lime tubes. Basic’ LEAD SULPHATE Lead and Zinc (gravimetric). — Digest 1 g. for ten min- utes in the cold with 20 c.c. of 10 per cent sulphuric acid. Filter, keeping most of the residue in the beaker, and wash twice by decantation with 1 per cent sulphuric acid. The filtrate from the sulphuric acid teatment is re- served for the determination of zinc which is carried out by any of the methods outlined under “Zinc Oxid.” Preferably precipitate as phosphate. Calculate the zinc to ZnO. Dissolve the residue in the beaker with hot concen- trated slightly acid ammonium acetate solution pouring the solution through the filter. Wash the latter with ammo- ANALYSIS OF PAINT MATERIALS 333 nium acetate and then with hot water. Dilute to 200 c.c., add an excess of a neutral saturated solution of potassium dichromate and bring to boiling. Allow to cool, and filter on a Gooch or alundum crucible. Dry at 130° and weigh as PbCrQk. Lead (volumetric). — Treat 0.5 g. sample with 30 c.c. of water and 5 c.c. of concentrated sulphuric acid, and proceed as outlined under ‘Estimation as Molybdate.” Sulphates.! — Dissolve 0.5 g. by boiling in a mixture of 25 c.c. water, Io c.c. aqua ammonia and enough con- centrated hydrochloric acid to give a slight excess. Dilute to 200 c.c. and add a piece of pure thick aluminium foil large enough to nearly cover the bottom of the beaker. This should be kept at the bottom by means of a glass rod. Boil gently until the lead is precipitated. When the lead no longer adheres to the aluminium, the precipi- tation may be considered complete. Filter and wash with hot water. A little sulphur-free bromine water is added to the filtrate, the latter is boiled, and sulphates determined by precipitation with barium chloride in the ordinary way. If desired the sulphates may be determined as indicated under Analysis of ‘Zinc Lead.” Sulphur Dioxid. — Digest about 2 g. in the cold with 5 per cent sulphuric acid, and titrate with = iodine solu- tion, using starch as indicator. ANALYSIS OF ZINC LEAD Lead. —1 g. of the material is heated on the steam bath with 20 c.c. of hydrochloric acid (1:1) and 5 g. of ammonium chloride. The solution is diluted to 250 c.c. with hot water and boiled. This treatment should suffice to dissolve a pure zinc lead. ! Holley, “Analysis of Paint and Varnish Products,” 1912, p. 104. 334 CHEMISTRY AND TECHNOLOGY OF PAINTS The insoluble residue, if any, is filtered, weighed, and examined for impurities. Neutralize the filtrate with ammonia, reacidify slightly with hydrochloric acid, and precipitate the lead with hydrogen sulphide. Allow the precipitate to settle, filter off the liquid, and wash the precipitate several times by decantation with hydrogen sulphide water. The precipitate is finally dissolved in hot, dilute nitric acid, treated with an excess of sulphuric acid, and evaporated to SO; fumes. Allow to cool, dilute cautiously with too c.c. of cold water, filter off the precipitated lead sulphate on a Gooch crucible, wash several times with dilute sulphuric acid, and finally once with alcohol. Dry at 130° C., and weigh as PbSQ,. Zinc. — The filtrate from the lead sulphide precipitate is boiled to expel hydrogen sulphide, treated while hot with a few drops of HNOs:, then rendered slightly am- *moniacal, and any precipitate which is formed is filtered off. The filtrate is then slightly acidified with acetic acid, heated to boiling and a stream of sulphuretted hydrogen passed in to precipitate the zinc. The latter is filtered and washed with water containing a small amount of acetic acid saturated with hydrogen sulphide, using a Gooch or alundum crucible for filtering. In filtering zinc sulphide, keep the crucible full of liquid or wash water until the precipitate is completely washed. Only then may the precipitate be allowed to drain free from wash water. The zinc sulphide is then dissolved in dilute hydro- chloric acid, the sulphuretted hydrogen expelled by boiling, and the zinc determined either volumetrically by the ferro-cyanide method or gravimetrically by precipitation with a slight excess of sodium carbonate, and ignition to oxid. ANALYSIS OF PAINT MATERIALS 335 Calcium and Magnesium. — The filtrate from the zinc sulphide is evaporated to a small bulk and the calcium determined by precipitating hot from a slightly ammoni- acal solution with ammonium oxalate. Magnesium is determined as usual. Soluble Salis. —'To determine the presence of zinc sul- phate, 1 g. is digested with too c.c. of water, filtered, and the sulphate determined in the filtrate as usual, with barium chloride. Total Sulphates.— Dissolve 25 g. of sodium car- bonate in a beaker with 25 c.c. of water, add o.5 g. of the sample, boil gently for about ten minutes and allow to stand for several hours. Dilute with hot water, filter and wash until the filtrate is about 200 c.c. Render the filtrate slightly acid with hydrochloric, boil to expel carbon dioxid and precipitate the sulphate with a slight excess of barium chloride solution. Filter, wash and weigh as BaSO,. Calculate the lat- fersto-PbsO.. ZINC OxIbD Insoluble. — Dissolve 1 g. in hot dilute acetic acid. Filter, wash and weigh any insoluble residue. If the latter is very small in quantity, it should be deter- mined by dissolving a proportionately larger quantity of zinc oxid. Zinc. — Neutralize the filtrate with ammonia, then make faintly acid with acetic acid, dilute to 300 c.c., and precipitate with sulphuretted hydrogen. The solution should be kept hot during the precipitation, and should smell strongly of hydrogen sulphide at the end. Allow the precipitate to settle, decant through an alundum or Gooch crucible, keeping the crucible full of liquid during the filtration, wash the precipitate in the beaker with a 336 CHEMISTRY AND TECHNOLOGY OF PAINTS hot 2 per cent acetic acid solution saturated with hydro- gen sulphide, finally transferring the zinc sulphide to the crucible and allowing the last wash water to drain com- pletely. The zinc sulphide is dissolved in dilute hydre- chloric acid and boiled to expel HS (test with lead acetate paper held in the escaping vapors from the beaker or flask to show the presence of hydrogen sulphide). Gravimetric Methods for Zinc. — (a) Precipitation as Phosphate The solution is rendered very faintly acid by almost completely neutralizing with ammonia, diluted to 150 c.c. and heated on the steam bath. Add to the solution on the steam bath about ten times as much di-ammo- nium phosphate! as zinc present. Heat for 15 minutes longer. The crystalline zinc ammonium phosphate is filtered through a Gooch or alundum crucible, washed with hot 1 per cent ammonium phosphate solution until free from chlorides, then with cold water and finally with so per cent alcohol. Dry at 120° C. for one hour and weigh as ZnNH.POk. (b) Precipitation as Carbonate The zinc chloride sclution is carefully neutralized in the cold with sodium carbonate solution until a precipi- tate begins to form. The solution is then heated to boiling, and precipitation completed by adding a slight excess of sodium carbonate (use phenolphthalein as indi- cator). Ammonium salts must not be present. Filter on a Gooch crucible, wash, ignite and weigh as ZnO. Volumetric Method. — Zinc is precipitated from hot somewhat acid solutions by the addition of potassium ferro-cyanide according to the following reaction: | 1 Dissolve in cold water and add dilute ammonia until faintly pink with phenolphthalein. ANALYSIS OF PAINT MATERIALS Go iON) ~I 3ZnCl, + 2KyFeCgNg = Zn3KyFe.(CN)» + 6KCI The end point is indicated by a solution of uranium ni- trate as outside indicator. A brown coloration is produced when a drop of the solution containing the excess of potassium ferrocyanide is ‘added to a drop of uranium nitrate solution on a spotting tile. Solutions Potassium Ferrocyanide.— Dissolve 21.6 g. of crystallized salt, KiFeC;N.«-3H.O in cold water and dilute to one liter. One c.c. of this solution is equivalent to about 0.005 g. zinc. Mrmiumeru trate, 6.98, eyo 25. 5% solution Ammonium chloride ..... 0.5... 10.0. per liter Standardization of Ferrocyanide. — Weigh out two or three portions of 0.2 to 0.25 g. of pure ignited zinc oxid. Dissolve in 1o c.c. of hydrochloric acid (1:2), add sodium carbonate solution or ammonia until a slight permanent precipitate is formed, redissolve the latter with one or two drops of hydrochloric acid, add 6 c.c. of concen- trated hydrochloric acid and to g. of ammonium chloride. Dilute to 180 c.c., heat to 70° C. and titrate with ferro- cyanide solution until the end point is reached. To - determine the end point rapidly divide the zinc solution into two unequal parts. Titrate the smaller part run- ning in the ferrocyanide solution 1 c.c. at a time. When an excess has been added pour in the rest of the zinc so- lution, run.in 1 c.c. less than the quantity of potassium ferrocyanide previously added, and finish the titration drop by drop. A blank must be deducted because of the excess of potassium ferrocyanide required to develop the brown coloration with uranium solution. To determine the allowance, add 6 c.c. of concentrated hydrochloric acid and 10 g. of ammonium chloride to 200 338 CHEMISTRY AND TECHNOLOGY OF PAINTS c.c. of water in a beaker, heat to 7o° C., and add the ferrocyanide solution until the brown coloration is ob- tained with the outside indicator. The correction should be less than 0.5 c.c. Deduct this amount from all future titrations. Determination of Zinc.—'To determine zinc in the solution obtained by dissolving ZnS in hydrochloric acid and expelling hydrogen sulphide, neutralize with ammonia or sodium carbonate, reacidify slightly with dilute hydro- chloric acid, and proceed as outlined under “ Standardiza- tion of Ferrocyanide.’’ The presence of a small amount of lead does not interfere with the accuracy of the above method. Soluble Impurities. — Most zinc oxids are contami- nated with small quantities of cadmium and traces of iron, copper and lead. The cadmium! is best determined by dissolving a relatively large amount, 25 to 50 g., of zinc oxid in dilute sulphuric acid, filtering, diluting to 4oo c.c. and precipitating as sulphide in the presence of an excess of about 5 c.c. of concentrated sulphuric acid in too c.c. of solution. Filter, wash, redissolve in sulphuric acid and reprecipitate as sulphide. Dissolve into a crucible with as small an amount of sulphuric acid as possible. Evaporate cautiously and ignite to CdSQk,. LITHOPONE Metuop I Zinc Oxid. — Digest 1 g. with 100 ‘Gey Oherpeneaemn acetic acid at room temperature for one half hour. Filter, wash and weigh the insoluble. The loss in weight represents the zinc oxid present. 1 For electrolytic method of determining Cadmium, see E. F. Smith’s “ Electro-Analysis.” ANALYSIS OF PAINT MATERIALS 339 Insoluble and Total. Zinc. — Treat 1 g. in a 200 c.c. beaker with 10 c.c. of concentrated hydrochloric acid, mix, and add in small portions 1 g. of potassium chlorate (this should be carried out under a hood); evaporate on the steam bath to $ the volume. Dilute with hot water, add 5 c.c. of dilute sulphuric acid (1:10), boil, filter, and weigh the insoluble. The latter is barium sulphate. The zinc is determined in the filtrate by the methods outlined under “Zinc Oxid.”’ Metuop II Soluble Salis. — Treat 2 g. of lithopone with 100 c.c. of hot water. Digest for a few minutes and filter on a Gooch crucible (test the filtrate for Ba, Zn and SQ,). Wash with hot water and finally once with alcohol. Dry the crucible in the air oven at 1too° C. and deter- mine loss in weight. The latter is equal to the per- centage of moisture present plus the water soluble salts. Zinc Oxid. — Digest for $ hour, without warming, a 1 g. sample with too c.c. of 1 per cent acetic acid. Filter, wash, and determine the zinc in the filtrate gravimetrically or volumetrically, as outlined under “Zinc Oxid.” Cal- culate to ZnO. Zinc Sulphide. — Transfer the filter paper and residue to a beaker, treat with dilute hydrochloric acid (1:4) and boil to drive off H.S. Filter, wash with hot water, and determine the zinc in the filtrate by the usual methods. Report as Zns. Barium Sulphate. — The residue is dried, ignited, treated with a few drops of concentrated sulphuric acid in the crucible, again ignited and weighed as BaSOQu. Test the latter for clay or silica. Should any be present, treat the residue with hydrofluoric and sulphuric acids 340 CHEMISTRY AND TECHNOLOGY OF PAINTS in a platinum crucible and evaporate to dryness. The loss in weight represents silica. ANALYSIS OF ‘TITANIUM WHITE? DETERMINATION OF BARIUM SULPHATE Weigh 4 gram sample into 250 c.c. Pyrex glass beaker; add 20 c.c. concentrated sulphuric acid and 7 or 8 grams sodium sulphate. Mix well and heat on hot plate until fumes of sulphuric anhydride are evolved and then heat directly over flame to boiling for five minutes or until solution is complete. Traces of silica, if any, remain as an insoluble residue. Cool, take up with too c.c. of water, boil and filter off barium sulphate and silica, washing with 5 per cent sulphuric acid to free residue from titanium. DETERMINATION OF TITANIUM The volumetric method used for determination of titanium is essentially that described by P. W. & E. B. Shimer; Proceedings of Eighth International Congress of Applied Chemistry; the method hereafter described differ- ing principally in the form of reductor and also in a few details of operation. REAGENTS Standard Ferric Ammonium Sulphate Solution. Dissolve 30 grams of ferric ammonium sulphate in 300 c.c. water acidified with to c.c. of sulphuric acid; add potassium permanganate drop by drop as long as the ‘ Courtesy Titanium Pigments Corp., 1923. ANALYSIS OF PAINT MATERIALS 341 pink color disappears, to oxidize any ferrous to ferric iron; finally dilute the solution to one liter. Standardize this solution in terms of iron. The iron value multiplied by 1.4329 gives the value in titanic oxide (TiO.); and iron value multiplied by .86046 gives the value of the solution in terms of metallic titanium. INDICATOR Saturated solution of potassium thiocyanate. REDUCTOR As a reductor a 500 c.c. dispensing burette is used. The internal dimensions of the burette are 13 inches by 22 inches. The reductor is charged with 1200 grams of 20 mesh amalgamated zinc, making a column about 12 inches high and having an interstice volume of about 135 c.c. This form of reductor is convenient, and when used as hereafter described is adapted to maintaining hot solutions, which is essential for complete reduction of the titanium. The reductor is connected to a liter flask for receiving the reduced titanium solution through a three-hole rubber stopper, which carries also an inlet tube for carbon dioxide supply, and outlet tube for connecting with the suction pump. The reductor is prepared for use by first passing through it a little hot dilute sulphuric acid followed by hot water, finally leaving sufficient hot water in the reductor to fill to the upper level of the zinc. The hot filtrate from the barium sulphate determination is now introduced; about 100 c.c. of water being drawn from the reductor into the original beaker to bring the 342 CHEMISTRY AND TECHNOLOGY OF PAINTS solution to about the upper level of the zinc. The water thus removed will not contain any titanium if the operation has been conducted as described, but it serves as a safe- guard and is also convenient to acidify this water with to c.c. sulphuric acid and reserve it on the hot plate to be used as an acid wash after the reduction of the sample solution. The titanium solution is allowed to remain in the re- ductor for to minutes. 7 While the solution is being reduced, the receiving flask is connected to the reductor and the air completely dis- placed by carbon dioxide, conveniently drawn from a cylinder of the liquefied gas. When the reduction is complete the receiving flask is connected with the suction pump, and while still con- tinuing the flow of carbon dioxide the reduced solution is drawn out, followed by the reserved acid wash and then three or four 100 c.c. washes with hot water. The dis- placement of the sample solution and washing of the zinc is so regulated by means of the stopcock that the reductor is always filled with solution or water to the upper level of the zinc. 3 When the washing is complete, gradually release the suction to prevent air being drawn back into the receiving flask. Disconnect the flask, add 5 c.c. of potassium thio- cyanate solution as indicator and titrate immediately with standard ferric ammonium sulphate solution, adding the solution rapidly until a brownish color is produced, which will remain for at least one minute. The method is also well adapted for determining titanium in other titanium products; suitable means being employed for bringing the titanium into sulphuric acid solution. | ANALYSIS OF PAINT MATERIALS 343 Constants for Titanium White: Titanium Dioxid (TiO.) — 25 per cent, Barium Sulphate (BaSO,) 75 per cent, specific gravity, 4.3. RED LEAD AND ORANGE MINERAL Lead Peroxid (Method I). — Dissolve 0.5 g. in a beaker with 30 c.c. of 2N nitric acid, heat to boiling to complete solution. Add 25 c.c. N/5 oxalic acid, accurately meas- ured from a pipette or burette, boil and titrate hot with KMnQ,. A blank containing the same quantities of nitric acid and oxalic acid is also titrated against the permanganate. The difference between the two titrations represents the -amount of PbO, reduced by oxalic acid. Pb30, + 4HNO;3 = 2Pb (NO3)2 + H.O + H3PbO3 PbO. + HeC.0O4 = PbO + H2O+ 2CO. Lead Peroxid (Method IT).— Mix together in a small beaker 1.2 g. of potassium iodide, 15 g. sodium acetate and 5 c.c. of 50 per cent acetic acid. Weigh off 0.5 g. of red lead in a 150 c.c. Erlenmeyer flask and add the above mixture to it. Stir until the lead is completely dis- solved. Dilute to 25 c.c., and titrate with N/r1o sodium thiosulphate, using starch as indicator. A little red lead, especially when it is not very fine in texture, at first resists solution in the potassium iodide mixture, but dissolves, on mixing, toward the end of the titration. Proceed with the titration as soon as the lead is in solution, so as to avoid loss of iodine by volatilization. The reaction involved in the above method is PbO» + AHI = PbI, + 2H.O + I, The lead peroxid is reduced in the presence of an excess of sodium acetate when treated with potassium iodide in acetic acid solution. 344 CHEMISTRY AND TECHNOLOGY OF PAINTS ANALYSIS OF IRON OxIDS Moisture. — Heat. 2 g. in*the air oven atmos Gaon two hours. Loss on Ignition. — Ignite 1 g. in a porcelain crucible to a red heat. The loss in weight consists of hygros- copic moisture, water of combination, sometimes organic matter, and carbon dioxid due to the presence of car- bonates. | * Insoluble. — Digest 1 g. of the oxid with 20 c.c. of hydrochloric acid (1:1) on the hot plate for 15 minutes. Filter, wash and weigh the insoluble residue. The latter may be examined to determine the presence of barytes, clay or silica. Iron Oxid.— Weigh off from 0.3 to 1.0 g., depend- ing upon the amount of iron oxid present, treat with 20 c.c. of hydrochloric acid (1:1) on the hot plate until the residue is white, and while hot reduce with a strongly acid stannous chloride solution until the iron solution is colorless, using only one or two drops in excess. Wash down the sides of the beaker and the cover glass with a little water, add all at once ro c.c. of a saturated solution of mercury bichloride, stir, and wash the whole into a large beaker containing 400 c.c. of cold distilled water to which has been added to c.c. of preventive solution. Titrate with N/1o potassium permanganate to a faint pink. In the case of magnetic oxids and certain purple oxids, solution is facilitated by the addition of 1 to 3 c.c. of a 25 per cent stannous chloride solution. Should the residue after digestion on the hot plate still show greenish or black, filter, wash, and determine the iron in the soluble portion as outlined below. ANALYSIS OF PAINT. MATERIALS 345 To determine iron in the insoluble portion, fuse in a porcelain crucible with five times its weight of potassium bisulphate for about } hour. Cool, dissolve in water and filter. Determine iron in the filtrate after reduction as outlined below. Stannous Chloride Solution. — Dissolve 50 g. of stan- nous chloride in too c.c. of hydrochloric acid and dilute to 1000 c.c. To preserve the solution, always keep a few pieces of metallic tin at the bottom of the bottle. PREVENTIVE SOLUTION: Crystallized Manganese Sulphate....... 67g NTIS Os CCNA ak ee 500 C.C Syrupy Phosphoric Acid (Sp. Gr. 1.7). ..138 c.c. Cencentiated sulphuric Acid)... .....130 C.c. Dissolve in the order named and dilute to 1 liter. ANALYSIS OF UMBERS AND SIENNAS To 0.5 to 1.0 g., depending upon the amount of iron oxid present, in a casserole, add 20 c.c. of hydrochloric acid (1:1) and 0.35 g. potassium chloride (or 0.25 g. ammonium chloride), and evaporate to dryness on the steam bath. Heat for 1o minutes longer to expel hydro- chloric acid. Dissolve the soluble salts in about 25 c.c. of hot water, filter and wash the insoluble residue. The latter is dried, ignited and weighed, and reported as insoluble or silicious matter. (When necessary analyze this separately as indicated under “Analysis of Silica, Asbestine or Clay’’.) To the filtrate, heated almost to boiling, there is added 3.0 g. of sodium acetate for every 0.3 g. of iron in solution, and 4oo c.c. of boiling water. Heat to incipient boiling. By this means the iron is quantita- tively precipitated as a basic acetate, while manganese 346 CHEMISTRY AND TECHNOLOGY OF PAINTS and other divalent metals of the group stay in solution. The precipitate is allowed to settle, the solution decanted off and filtered; the precipitate is washed several times with hot water, dissolved in a small amount of hot dilute hydrochloric acid, and either precipitated with ammonia or determined volumetrically as under “Analysis of Iron Oxids.” The filtrate is evaporated to about half its volume, treated with an excess of bromine water, and then boiled until the precipitated manganese dioxid be- comes floccular. The precipitate is then filtered off, washed, and ignited to Mn;Q,. Calcium and magnesium are determined in the fil- trate in the usual way. When appreciable quantities of these two elements are present, it is best to separate the manganese by precipitation as sulphide. To determine manganese as sulphide, heat the neutral solution to boiling, add an excess of ammonia and am- monium sulphide, and continue the boiling until the man- ganese sulphide. becomes a dirty green. Decant through a Gooch crucible, using gentle suction, keeping the cru- cible filled all the time. Wash the precipitate twice by — decantation with 5 per cent ammonium nitrate solution con- taining a little ammonium sulphide, add to the crucible and filter, allowing the crucible to drain. The filtrate is acidified with dilute acetic acid boiled to expel hydro- gen sulphide, and the calcium and magnesium deter- mined as usual. The precipitated manganese sulphide is dissolved in a little hot dilute hydrochloric acid, evaporated to expel hydrogen sulphide, and precipitated as carbonate or phosphate. In the first case the man- ganese is ignited and weighed as Mn;Qk. Colorimetric Determination of Manganese.! — Dissolve ' Treadwell, Volume II, pages 127, 128. Marshall, Chem. News, 83, 76 (1904). Walters, Chem. News 84/239 (1904). ANALYSIS. OF PAINT MATERIALS 347 0.5 g. of umber or sienna in about ro c.c. of hydrochloric acid (1:1) in a casserole, add an excess of nitric acid and evaporate to dryness to drive off the hydrochloric acid. Cool, add 20 c.c. of cold nitric acid (specific gravity 1.2) filter and wash with the least quantity of cold water into a i100 c.c. graduated flask. Make up to the mark. Remove to c.c. by means of a pipette to a graduated test tube, add io c.c. of silver nitrate! solution, and 2.5 c.c. of ammonium persulphate? solution, mix, and place the tubes in water at 80 to 9o° C. until bubbles of gas arise, and remain at the top for a few seconds. Cool the test tubes and compare against standard tubes made with known amounts of manganese. MERCURY VERMILION This pigment is very expensive and therefore quite often adulterated. The possible adulterants are organic lakes, orange lead chromes, red lead, and iron oxids, as well as barytes, silica or clay. Its high specific gravity (8.2) and its insolubility in alkalies, and in any one acid, distinguish it from all other pigments of like color. A pure vermilion can be volatilized completely on heating, leaving no residue. On account of the ex- tremely toxic properties of mercury vapors, such volatili- zation should be carried out in a hood having a good draft. Barytes, Silica or Clay. — Dissolve 2 g. in aqua regia, or hydrochloric acid with a little potassium chlorate, and after evaporating to dryness take up with boiling water and a little hydrochloric acid. Filter and weigh the residue. 1 7.38 g-AgnOs in 1000 c.c. of water, 2 20% solution. 348 CHEMISTRY AND TECHNOLOGY OF PAINTS Lead. — Evaporate the filtrate from the above with an excess of dilute sulphuric acid to SO; fumes, and deter- mine lead as PbSO,. (Calcium must be absent.) Free mercury, free sulphur and iron may be identified by dissolving the mercury vermilion in potassium mono- ‘sulphide (1:1), in which it dissolves readily. The solu- tion is colorless after the iron sulphide has settled out. Free mercury settles to the bottom of the dish as a gray sediment. Free sulphur is recognized by the yellow coloration of the solution. It may also be detected in the usual way by digesting with potassium hydroxid or extraction with carbon disulphide (if present in crystalline form). The quantitative determination is carried out by extracting with soda solution and oxidation to sulphate. For separating foreign adulterations such as barytes, clay, litharge, chrome red, brick dust, etc., potassium sul- phide may be used to advantage. After filtering, wash with dilute KOH solution and not with water, otherwise the Brunner’s salt decomposes with separation of black HgS. The coal tar colors are identified by extraction with alcohol; carmines by the drop test with ammonia on filter paper. For detecting arsenic sulphide, boil with caustic soda, acidify with hydrochloric acid and introduce H.S gas into the solution. ANALYSIS OF CHROME YELLOWS AND ORANGES Organic Matter. —'Test with alcohol to determine pres- ence of organic coloring matter. Insoluble. — Boil 1 g. for about 5 minutes with 20 c.c. of concentrated hydrochloric acid, adding 1 or 2 c.c. of alcohol drop by drop. Dilute with about roo c.c. of boiling water. Boil a few minutes longer. Filter, wash ANALYSIS OF PAINT MATERIALS 349 with boiling water, and weigh the insoluble. Test the latter for barium sulphate, clay or silica. Lead. — Neutralize the filtrate with ammonia until a slight permanent precipitate appears. Reacidify shghtly, using an excess of not more than 1.5 ¢c.c. of concentrated hydrochloric acid in too c.c. of solution. Dilute to 200 c.c. Precipitate the lead with hydrogen sulphide. Fil- ter, wash with H.S water, dissolve the PbS in hot dilute nitric acid, boil to expel H.S, add to c.c. of dilute H.SO, (1:1), evaporate to fumes of SO; and determine lead gravimetrically or volumetrically as outlined under “White Lead.” Chromium. — Evaporate the alcoholic filtrate from the PbSO, almost to dryness and mix with the filtrate from PbS. The chromium is determined by precipitating hot with a slight excess of ammonia. Filter, wash, ignite and weigh as Cr.Qs. Zinc. — The filtrate from chromium hydroxid is ana- lyzed for zinc by precipitating with hydrogen sulphide. Bee inc Oxid:” CHROME GREENS Preliminary Test. — Determine the presence of organic coloring matter by extraction with alcohol. Insoluble. —In a small evaporating dish heat 1 g. sample at as low a temperature as possible until the blue color is completely discharged. ‘Transfer to a beaker, and boil with 20 c.c. of concentrated hydrochloric acid and a little alcohol to dissolve the soluble portion. Dilute with hot water, boil, filter, wash, and weigh the insoluble por- tion. Examine the latter for silica, clay or barytes. Lead. — Determine in the filtrate after neutralizing with ammonia and reacidifying slightly with hydro- chloric acid as under “‘Chrome Yellows.”’ 350 CHEMISTRY-AND TECHNOLOGY: OF PAINGS Chromium, Iron and Aluminium.— Boil the filtrate from the lead sulphide to expel hydrogen sulphide, add a few drops of nitric acid and about 2 g. of ammonium chloride. Heat to boiling, and precipitate iron, aluminium, and chromium as hydroxids with ammonia in slight excess. Filter and wash the precipitates. Dissolve the mixed hydroxids in a small amount of hot dilute hydrochloric acid and dilute to r50c.c. Heat to boiling and treat with an excess of sodium hydroxid, and bromine water. Filter and wash. Redissolve the ferric hydroxid in dilute hydrochloric acid, and determine iron by the usual methods. The filtrate is acidified faintly with hydrochloric acid and aluminium hydroxid precipitated with a slight excess of ammonia. The filtrate from aluminium hydroxid is carefully acidified with acetic acid, and the chromium precipitated by the addition of barium acetate to the hot solution. Allow to stand for some time, and filter through a Gooch or alundum crucible (using gentle suction). Wash with alcohol, and dry in hot closet. Finally ignite at a dull red heat by suspending the crucible inside a larger por- celain crucible by means of an asbestos ring. If desired the chromium present as alkali chromate may be reduced to chromic salt by evaporating with hydrochloric acid and alcohol. The chromium may then be precipitated by ammonia and weighed after ignition as Cr.O3. Calcium and Magnesium. — Determine as usual in the filtrate from iron, aluminium and chromium hydroxids. Sulphates. — Treat 1 g. as mentioned in the second paragraph of this section. Determine sulphates as under “Zinc Lead.” d Nitrogen. — Determine by the Kjeldahl-Gunning method. ANALYSIS OF PAINT MATERIALS 351 PRUSSIAN BLUE Hygroscopic Moisture. — Determine on a 1 g. sample by heating for 2 hours at 1o5° C. Water of Composition. — Determine by difference after the other constituents have been obtained. Ferrocyanic Acid.1— Treat 0.5 g. with to c.c. of nor- mal potassium hydroxid solution in a flask. Boil for 5 Mmimuress diuute with so c.c.-of hot water, filter, and wash the ferric hydroxid. The filtrate containing a solution of potassium fer- rocyanide is slightly acidified with sulphuric acid, 2 to 3 g. of ammonium persulphate are added, and the liquid boiled from 20 to 30 minutes. Any blue color which persists is removed by the addition of hydrochloric acid and a little more persulphate. The iron is precipitated with ammonia by the usual method gravimetrically or volumetrically. Calculate as FeC,Ne. Cyanogen. —If desired, the total nitrogen in Prussian blue may be determined by the Kjeldahl-Gunning method as outlined in Bulletin 107, Bureau of Chemistry, U. S. Dept. of Agriculture. To determine the amount of Prussian blue, multiply the total iron content by 3.03 or nitrogen content by 4.4. The results thus obtained are fairly approximate. They are not exact since the composition of Prussian blue is variable. The pure Prussian blue should contain about 20 per cent of nitrogen and 30 per cent of iron, and less than 7 per cent of moisture. The sulphuric acid used in determining the nitrogen by the Kjeldahl-Gunning method should not be blackened due to the presence of organic adulterants. Lwiset eal O04, «40.1020; 352 CHEMISTRY AND TECHNOLOGY OF PAINTS fron. — To determine the total iron in Prussian blue, ignite 1 g. gently until the blue color is completely dis- charged. Dissolve the residue in to c.c. of hydrochloric acid (1:1), filter, make up to roo c.c. in a graduated flask. Determine Fe,O; in 50 c.c. in this solution (calculate to metallic iron). In the other 50 c.c. of the filtrate determine Fe,O; + Al,O; by the usual methods. Calculate Al,O; by difference. Report as metallic aluminium. Calcium.— Determine as usual in the filtrate from Fe,O; + Al.Os. Alkali Metals. — Determine by the usual methods. ANALYSIS OF ULTRAMARINE I The ultramarine is finely powdered and dried at 100°. 2 to 10 g. are weighed off, digested with water, filtered, - the filtrate diluted to 500 c.c., and 100 c.c. taken for each of the following determinations. (a) Na2S.0;— determine with iodine solution and starch. Calculate to Na.S,O; + Ag. ; (b) NasSO,— determine by precipitating with barium chloride in acid solution. (c) NaCl — determine by precipitating with AgNO; (NaCl is rarely present in ultramarine). to to 20 grams of ultramarine are washed two or three times by decantation (to obtain a clear filtrate, alcohol is added). Evaporate almost to dryness with a dilute solu- tion of sodium sulphite! on the water bath. Wash until a test of the ultramarine moistened with water and fil- tered gives no trace of turbidity with barium chloride. ' In order to remove free S, for CS, extracts only 40 to 60% of the same. ANALYSIS OF PAINT MATERIALS 353 (he ultramarine dried at 130 to 140° is again powdered and placed hot into a glass stoppered flask. II Estimation of silicic acid, silica, clay and total sulphur. 1 g. of the dried substance is weighed into a porcelain dish, stirred up with water and treated with 1 to 2 c.c. of bromine. If it is partially dissolved (as shown by the yellow coloration of the liquid) 15 to 20 c.c. of nitric acid are added and the whole evaporated to dryness on the water bath. Take up with water, add 20 c.c. of hydrochloric acid and evaporate again (to remove nitric acid which would increase the BaSO, precipitate, and to render silicic acid insoluble). Treat with hydrochloric acid, digest warm for a few hours, dilute with water and filter. On the filter are left silicic acid and sand. To determine total sulphur, the filtrate is heated to boiling and precipitated with barium chloride. ISH Estimation of alumina and of soda. t g. of ultramarine, washed and dried as in number I, is carefully mixed with water and treated with an ex- cess of hydrochloric acid. After standing for a while it is heated until the solution settles clear. It is then fil- tered, leaving sulphur, sand and silicic acid undissolved. The residue is weighed after ignition. The filtrate is evaporated to dryness, the residue moistened with water and hydrocloric acid and again dried. Take up with hydrochloric acid, dilute with water after standing for some time and filter. On the filter is left silicic acid, which, added to the residue obtained in the first filtra- tion, gives the content of total silicic acid and sand. The filtrate is evaporated to dryness to remove excess hydro- 354 CHEMISTRY AND TECHNOLOGY OF PAINTS chloric acid. The residue is dissolved in water, precipi- tated with ammonia and the whole thoroughly dried in the water bath. (This facilitates complete washing of the alumina.) Take up the residue with hot water, add a few drops of ammonia, heat and filter. Alumina on the filter is determined and weighed. For determining soda, the filtrate is treated with sul- phuric acid and a little fuming nitric acid and evaporated to dryness. The residue is strongly ignited and the Na.SO, calculated to Na. | 3 BLACK PIGMENTS (Carbon Black, Lampblack, Vine Black, Bone Black) Moisture. — Determine on a 2 g. sample by heating for two hours at 105° C. Volatile. — Heat for to minutes over a Bunsen flame - in a well-covered porcelain crucible. Ash. — Determine on a 1 g. sample, ignite over a Bunsen burner with free access of air. When the ash is large in quantity, cool, moisten with a solution of ammo- nium carbonate and ignite again gently. Soluble and Insoluble Ash.— Treat the ash obtained by the above procedure with 5 to to c.c. of dilute hydro- chloric acid, heat, filter, wash and weigh the insoluble portion. Calculate the percentage of acid-soluble ash from the total ash and the acid-insoluble ash. Certain blacks are sometimes adulterated with Prus- sian blue. To detect the latter, boil with dilute caustic soda, filter, acidify the filtrate with dilute hydrochloric acid, and add a mixture of ferric chloride and ferrous sulphate. The formation of a blue precipitate indicates the presence of Prussian blue. ANALYSIS OF PAINT MATERIALS 355 GRAPHITE Heat 1 g. of the finely powdered graphite to a dull red heat and calculate the loss in weight as water. The dried substance is intimately mixed with 3 g. of a mixture of equivalent parts of K,CO; and Na,CO; and placed in a crucible. 1 g. of KOH or NaOH is sprinkled over the surface of this mixture and the whole heated slowly to redness. ‘The mass fuses, swells and forms a crust on top, which must be broken with a stout platinum wire. After fusing for one half hour, the melt is cooled, heated with water for ~ hour almost to boiling, filtered, washed well and the liquids set aside. The insoluble is dried, placed in a dish, the filter ash added and about 3 g. of HCl (specific gravity 1.18) poured in. After several minutes a slight gelatinization sets in due to the decom- position of the small residue of alkali silicate. The addi- tion of a little more hydrochloric acid brings the silicic acid into solution. After digestion for one hour, dilute with water, filter and wash out. The residue on the fil- ter is pure carbon, which, after drying and gentle ignition, is welghed. The acid filtrate is united with the alkaline one obtained above, more HCl added until weakly acid, evaporated to dryness, and silicic acid, alumina and iron oxid determined as usual. BLANC FIXE Water Soluble Salts. — Owing to the variety of methods employed in the technical production of blanc fixe, a preliminary qualitative examination of the material is always essential before proceeding with the quantitative analysis. Digest about 5 g. with 150 c.c. of hot water and filter. Examine the filtrate to detect the presence of 356 CHEMISTRY AND TECHNOLOGY OF PAINTS water so'uble salts. Determine the amount of water soluble salts, by difference, on a 1 g. sample. Acid Soluble.— Digest 1 g. of blanc fixe with hot water, wash by decantation and filter, keeping as much of the residue as possible in the beaker. Discard the filtrate and treat the residue in the beaker with about 25 c.c. of hot dilute HCl (1:3); filter through the filter paper used above, wash and ignite. Add 1 drop of nitric and 2 drops of sulphuric acid, evaporate, ignite again and weigh. Cal- culate % acid soluble from loss in weight, % water soluble and % moisture. | | BaSO,.— Proceed as outlined below under barytes (fusion in platinum with Na.CO;) to determine barium sulphate and silica (Page 359). Iron. — Determine colorimetrically. Silica. —'To determine qualitatively ' whether a sample of blanc fixe is free from silica or clay, heat about 0.5 g. with ro to 15 c.c. of concentrated sulphuric acid. A pure blanc fixe or barytes dissolves completely. Silicious matter remains undissolved. Determine the amount of silicious matter on a 1. g. sample by evaporating with a few c.c. of hydrofluoric acid and several drops of sulphuric acid. ANALYSIS OF WHITING Carbon Dioxid. — Determined as outlined under “ White Lead.” Calcium. — Determined by the usual methods. GYPSUM OR CALCIUM SULPHATE Calcium and Sulphates. — Determine by the usual methods. Moisture. — Dry 2 g. in a vacuum dessicator over sulphuric acid to constant weight. 1 Method developed in the laboratory of Toch Brothers. ANALYSIS OF PAINT MATERIALS 357 Combined H,O and Moisture. — Heat 1 g. in a covered porcelain crucible on an asbestos plate for 15 minutes, then heat the bottom of the crucible to dull redness for Io minutes over a Bunsen burner, remove the cover and heat for 30 minutes at a slightly lower temperature. Cool and weigh rapidly. SILICA, ASBESTINE, CLAY BARYTES Hygroscopic Moisture. — Determine on a 2 g. sample by heating for 1 hour at 1os° C. Loss on Ignition. — Determine on a 1 g. sample. This is largely water of composition, unless carbonates are present. Complete Analysis. — Mix 0.5 g. in a platinum crucible intimately with about 5 g. of anhydrous sodium car- bonate. Add a thin layer of the latter on top, cover the crucible and heat gently over a Tirrill or Tech burner for a short time. Raise the temperature gradually to the full heat of the burner. Finally heat for a short time over the blast lamp. Allow to cool, then heat the lower part of the crucible to dull redness, and cool again. Add a little water, heat carefully to boiling and the melt will readily separate trom the crucible. Place the melt in an evaporating dish; wash the crucible with a little hot water, and add to the dish. If barytes, or blanc fixe is present, the melt is digested with hot water until completely disintegrated, the barium carbonate is fil- tered off and washed, and the barium determined as outlined under barium carbonate. The filtrate is then treated in a large covered beaker with concentrated hydrochloric acid. After a certain amount of acid has been added, the silicic acid separates out as a gelatinous mass, which has to be broken up in order to obtain inti- mate admixture with the acid. After an excess of acid 358 CHEMISTRY AND TECHNOLOGY: OF “PAINTS has been added, the solution is heated to boiling, trans- ferred to a porcelain or platinum dish and evaporated to dryness. It is essential that dehydration of the silica be carried out twice! at the temperature of the steam bath and that the insoluble silica be filtered off before evaporating the second time. Filter, wash, combine the insoluble residues from the two dehydrations, ignite in a platinum crucible and weigh. Drive off SiO. with a few c.c. of HF and several drops of H.SO,. Ignite and reweigh.- The loss in weight is silica. Iron and Aluminium Oxids.— Treat the filtrate from the silicic acid with a few drops of concentrated nitric acid and to to 20 c.c. of a cold saturated solution of ammonium chloride. Heat to boiling and _ precipitate with a slight excess of ammonia. Allow the precipitate to settle, filter off the clear liquid and wash twice by decantation. with hot water. Redissolve the ferric and aluminium hydroxids by running hot dilute hydrochloric acid through the filter paper into the beaker containing the major portion of the precipitate. Reprecipitate with ammonia, as before, filter, wash and ignite wet in the platinum crucible containing the residue obtained after S10. was volatilized with HF and H,SO, Weigh as Fe,O; + Al.Os. For the determination of iron in the mixed oxids, see Treadwell and Hall, Vol. II, p. roo. Calcium. — Evaporate the filtrates from the ferric and aluminium hydroxids to a small volume. Heat to boil- ing and precipitate with a boiling solution of ammonium oxalate. Allow to stand for several hours. Filter and wash. Puncture the filter paper with a glass rod, wash the precipitate into a beaker with a stream of water from the ' Hillebrand, “Analysis of Silicate and Carbonate Rocks.” ANALYSIS OF PAINT MATERIALS 359 wash bottle, and pass 20 c.c. of hot dilute sulphuric acid (1:1) over and through the filter paper. Heat to go° C. and titrate with N/1o KMnOQ,. Magnesium. — Evaporate the filtrate from the calclum oxalate to dryness, and ignite in a porcelain dish. Moisten the residue with a little concentrated hydrochloric acid and dissolve in hot water. Filter and determine mag- nesium in the filtrate. Heat to boiling and treat with an excess of sodium or ammonium phosphate. Add an amount of ro per cent ammonia equal to § of the volume of solution. Allow to cool and set aside for a few hours. Filter through an alundum crucible, wash with 2.5 per cent ammonia, dry, ignite slowly at first and finally strongly until the precipitate is white. Weigh as Mg.P.O,. Alkalies. —See J. Lawrence Smith (Bulletin 422, U. S. Geologic Survey). BARYTES Make a preliminary test for lead compounds. In the absence of the latter weigh off 1 g. sample and mix with 5 g. anhydrous sodium carbonate in a platinum crucible. Fuse over the blast lamp for a half hour, occa- sionally imparting a rotary motion to the crucible to insure thorough reaction. Allow to cool, then heat the lower part of the crucible to dull redness, and cool again. Add a little water, bring carefully to boil, and the melt will readily separate from the crucible. Place in an evaporating dish, add too c.c. of water, and digest on the steam bath until completely disintegrated. Filter and wash the insoluble residue (BaCO;) until free from soluble salts. Dissolve the BaCO; with 25 c.c. of hydro- chloric acid (1:3), catching the filtrate and passing it through the filter to insure complete soluticn of the barium carbonate. Boil to expel carbon dioxid, neu- 360 CHEMISTRY AND TECHNOLOGY OF PAINTS tralize the filtrate with ammonia, reacidify with a few drops of hydrochloric acid, heat to boiling, and precipi- tate with dilute sulphuric acid. Filter and wash on a Gooch crucible, dry at 130° C. and report as BaSQu. In the presence of lead, first extract the barytes with hot concentrated ammonium acetate solution before proceeding with the sodium carbonate fusion, since the presence of metallic lead in the fusion will ruin the platinum crucible. Iron. — Determine colorimetrically. Clay and Silica. — Acidify the filtrate from the barium carbonate with hydrochloric acid, evaporate to dryness on the steam bath, heat for 20 minutes longer on the steam bath, and extract with hot water and a little hydrochloric acid. Filter, wash and weigh the insoluble SiO.. Determine alumina in the filtrate from SiO, as usual. See also determination of silica in blanc fixe (p. 356). In reporting the presence of silica and alumina, it must be remembered that the reagents used in the above determination, sodium carbonate and ammonia, almost always contain appreciable quantities of silica and alu- mina. Especially is this true of aqua ammonia, except when kept in bottles lined with ceresin or paraffin wax. ANALYSIS OF BARIUM CARBONATE Water Soluble Salts. — Determine by difference in a 1 g. sample, treat with hot water, filter, wash, and weigh the insoluble. Insoluble. — Dissolve about to g. in dilute hydro- cnloric acid. Heat to boiling, filter, wash and weigh the insoluble residue. The latter is generally silicious, but should be examined to determine the presence of barium. ANALYSIS OF PAINT MATERIALS 261 Barium. — Dissolve o.5 g. in dilute hydrochloric acid, neutralize with ammonia, then reacidify faintly with hydrochloric acid. Dilute to too c.c., heat to boiling, and precipitate with hot dilute sulphuric acid. Filter on a Gooch crucible, wash, and dry at 130° C. Calculate BaSO, to BaCO;. For the separation of barium, cal- cium, and strontium from each other, see Treadwell and ane Chem:,; Vol. 11, p. 70. Carbon Dioxid.— Determine by evolution as outlined under ‘White Lead.” Tyvon.— Treat 2 g. in a beaker with 15 c.c. of water and sufficient nitric acid to dissolve the barium carbonate. Boil for several minutes to expel carbon dioxid and to convert all the iron to the ferric state. Filter and wash the residue. Cool the filtrate, neutralize with ammonia and acidify faintly with nitric acid. Wash the contents of the beaker into a 100 c.c. Nessler cylinder, add 15 c.c. of dilute ammonium thio- cyanate (1:20) and dilute to the mark. The depth of the blood red color developed is a measure of the amount of iron present. Compare with a blank made as follows: Prepare a standard solution of ferric ammonium sul- phate by dissolving 0.7022 g. of ferrous ammonium sul- phate in water. Acidify with sulphuric acid, heat to boiling and oxidize the iron by the addition of a solu- tion of potassium permanganate. Only the faintest excess of permanganate should be added. The faint pink tinge due to the latter soon disappears. The solution is cooled and diluted to 1 liter. One c.c. of this solution is equivalent to o.ooo1 g. of iron. Into a too c.c. Nessler cylinder add about the same amount of nitric acid as was used to dissolve the barium 1 Modified Thompson & Schaeffer method. J. Ind. Eng. Chem. 1912, 659. 362 CHEMISTRY AND TECHNOLOGY OF PAINTS carbonate, and 15 c.c. of ammonium thiocyanate solution. Dilute to too c.c. and add the standard ferric ammonium sulphate solution, drop by drop, until the color exactly matches that developed in the sample being tested. One c.c. of the solution is equivalent to o.o1 per cent iron when a 1. g. sample is used. Not more than 2 or 3 c.c. of the standard should be required to equal the color; otherwise, the color becomes too deep for comparison. Sulphur.— For colorimetric determination see Tread- well & Hall, Vol. II, pages 354-7. Chlorine. — Determine in the water soluble portion (acidified with nitric acid) by precipitating hot in the presence of a slight excess of silver nitrate, filter on a Gooch or alundum crucible, wash, and weigh the insoluble AgCl after drying at 130° C. ANALYSIS OF MIXED WHITE PAINTS I... By: useof Aceng Ae Treat 1 g. of the mixed white pigment with 22 c.c. of water and to c.c. of glacial acetic acid. Boil, filter, and wash with water. The filtrate is heated to boiling, and precipitated with hydrogen sulphide. Filter off the lead and zinc sulphides, dissolve in hot dilute nitric acid, and determine lead and zinc as usual. Calculate the lead to white lead, and zinc to oxid. The filtrate from lead and zinc sulphides is tested for Ba, Ca, and Mg. Determine and calculate to carbonates. To the residue from the acetic acid treatment add 10 c.c. of water, ro c.c. of strong hydrochloric acid, and s g. ammonium chloride. Heat on steam bath for 5 minutes, dilute with boiling water to 400 c.c., boil, filter, wash, ignite and weigh the insoluble. Examine for silica, clay, barytes or asbestine. ANALYSIS OF PAINT MATERIALS 363 Precipitate the lead in the filtrate with hydrogen sul- phide, filter and wash. Dissolve in hot dilute nitric acid, and determine as usual. Report as PbSO,. The fil- trate is boiled to expel hydrogen sulphide, a few drops of nitric acid, ammonium chloride, and ammonia in excess are added to precipitate iron and aluminium. Calcium is determined in the filtrate as usual. Report as CaSQ,. II. By G. W. Thompson, (Jour. Soc. Chem. Ind. 15, 432) “The qualitative examination for the elements pres- ent may be determined as follows: Effervescence with concentrated hydrochloric acid indicates carbonic acid, sulphuretted hydrogen if zinc sulphide is present, or sul- phurous acid if lead sulphite is present. These latter two may be recognized by their odors. Boil a portion of the paint with acid ammonium acetate and test a portion of the filtrate for sulphuric acid with barium chloride. Test another portion of the same _ solution with sulphuric acid in excess for lead and test filtrate for zinc by making alkaline with ammonia, and adding ammonium sulphide. Test another portion of the am- monium acetate solution for lime by making alkaline with ammonia, adding ammonium sulphide, filtering and adding ammonium oxalate to filtrate. The portion insoluble in ammonium acetate, in the absence of sul- phite of zinc and sulphate of lead may be barytes, China clay, or silica. The qualitative examination of this residue is best combined with quantitative examination given further on.”’ “The oxids and elements, the presence of which is usually possible in a white paint, are: carbonic acid, water (combined), sulphuric acid, sulphurous acid, sulphur (combined as sulphide), silica, barium oxid, calcium oxid, zinc oxid, and zinc combined as sulphide, lead oxid, aluminium oxid.” 364 CHEMISTRY AND TECHNOLOGY OF PAINTS “In the absence of sulphuric acid, the lead soluble in acetic acid may be directly calculated to white lead.” “Sulphuric acid may exist in two conditions, in one it is soluble in ammonium acetate, and in the other, as in barytes, it is insoluble in ammonium acetate. That soluble in ammonium acetate may be determined by precipitating with barium chloride in that solution. Sulphuric acid in barytes is best calculated from the barium present, and determined as described later on. Sulphurous acid may be determined by oxidation to sul- phuric acid, or its determination may be based on the insolubility of lead sulphite in ammonium acetate. For instance, one portion of the sample is oxidized with nitric acid and the total lead determined. Another portion is treated directly with ammonium acetate, and the lead soluble in that menstruum determined. The difference between the two determinations is the lead present as sulphite, from which we may calculate the sulphurous acid present. Sulphur as sulphide is always present as zinc sulphide, which is never used in the presence of lead compounds. It may be determined by oxidation with bromine water and precipitation with barium chloride, or by determining the zinc insoluble in ammonium acetate. Silica may be determined by treating the matter insoluble in ammonium acetate with hydrofluoric acid and sulphuric acid. The loss on ignition is silica, or it may be determined by fusing the residue in the regular way. Barium oxid is determined by precipitation with sulphuric acid from hydrochloric acid solution of that part of fused residue insoluble in water.” Raprp METHODS FOR WHITE PIGMENTS ‘Sample 1 is a mixture of barytes, white lead, and zinc oxid. ANALYSIS OF PAINT MATERIALS 365 “Two I-gram portions are weighed out. One is dissolved in acetic acid and filtered, the insoluble matter ignited and weighed as barytes, the lead in the soluble portion precipitated with dichromate of potash, weighed in Gooch crucible as chromate, and calculated to white lead. “The other portion is dissolved in dilute nitric acid, sulphuric acid added in excess, evaporation carried to fumes, water added, the zinc sulphate solution filtered from, barytes and lead sulphate and precipitated directly as carbonate, filtered, ignited, and weighed as oxid. “Sample 2 is a mixture of barytes and so-called sub- limed white lead. “Weigh out three 1-gram portions. In one determine zinc oxid as in Case 1. ‘Treat a second portion with boiling acetic acid, filter, determine lead in filtrate and calculate to’ lead oxid. Treat third portion by boiling with acid ammonium acetate, filter, ignite, and weigh residue as barytes, determine total lead in filtrate, deduct from it the lead as oxid, and calculate the remainder to sulphate. Sublimed lead contains no hydrate of lead, and its relative whiteness is probably due to the oxid of lead being combined with the sulphate as basic sulphate. Its analysis should be reported in terms of sulphate of lead, oxid of lead, and oxid of zinc. “Sample 3 is a mixture of barytes, sublimed lead, and white lead. “Determine barytes, zinc oxid, lead soluble in acetic acid and in ammonium acetate, as in Case 2; also deter- mine carbonic acid, which calculate to white lead, deduct lead in white lead from the lead soluble in acetic acid, and calculate the remainder to lead oxid. “Sample 4 is a mixture of barytes, white lead, and carbonate of lime. 366 CHEMISTRY AND TECHNOLOGY OF PAINTS “Determine barytes and lead soluble in acetic acid (white lead) as in Case 1. In filtrate from lead chromate precipitate lime as oxalate, weigh as sulphate, and cal- culate to carbonate. Chromic acid does not interfere with the precipitation of lime as oxalate from acetic acid solution. ‘Sample 5 is a mixture of barytes, white lead, zinc oxid, and carbonate of lime. ‘Determine barytes and white lead as in Case 1. Dissolve another portion in acetic acid, filter and pass sulphuretted hydrogen through the boiling solution, filter, and precipitate lime in filtrate as oxalate; dissolve mixed sulphides of lead and zinc in dilute nitric acid, evaporate to fumes with sulphuric acid, separate, and determine zinc oxid as in Case 1. ‘Sample 6 is a mixture of barytes, white lead, sub- limed lead, and carbonate of lime. ‘Determine barytes, lead soluble in acetic acid and in ammonium acetate, as in Case 2, lime and zinc oxid, as in Case 5, and carbonic acid. Calculate lime to car- bonate of lime, deduct carbonic acid in it from total carbonic acid, calculate the remainder of it to white lead, deduct lead in white lead from lead soluble in acetic acid, and calculate the remainder to oxid of lead. “Sample 7 contains sulphate of lime. ‘“Analyses of paints containing sulphate of lime present peculiar difficulties from its proneness to give up sulphuric acid to lead oxid if white lead is present. Sulphate of lime and white lead boiled in water are more or less mutually decomposed with the formation of sul- phate of lead and carbonate of hme. A method for the determination of sulphate of lime is by prolonged washing with water with slight suction in a weighed Gooch crucible. This is exceedingly tedious, but thoroughly ANALYSIS OF PAINT MATERIALS 367 accurate. A reservoir containing water may be placed above the crucible, and the water allowed to drop slowly into it. This may take one or two days to bring the sample to constant weight, during which time several liters of water will have passed through the crucible. Another method for separating the sulphate of lime is by treatment in a weighed Gooch crucible with a mixture of nine parts of 95 per cent alcohol and one part of glacial acetic acid. Acetates of lead, zinc, and lime being soluble in this mixture, the residue contains all the sul- phate of lime and any sulphate of lead and barytes which Iiay-be present. Determine the lead and lime as in sample 4, and calculate to sulphates. Sulphate of lime should be fully hydrated in paints. To determine this, obtain loss on ignition; deduct carbonic acid and water in other constituents; the remainder should agree fairly well with the calculated water in the hydrated sulphate of lime, if it is fully hydrated. If, after washing a small portion of the sample with water, the residue shows no sulphuric acid soluble in ammonium acetate, the sulphate of lime may be obtained by determining the sulphuric acid soluble in ammonium acetate and calculating to sulphate of lime. The difficulty is in determining the sul- phate of lime in the presence, or possible presence, of sulphate of lead. To illustrate the analysis of sample of white paint containing sulphate of lime and the difficulty attending thereon, we would mention a sample containing sublimed lead, white lead, carbonate of lime, and sulphate of lime. In such a sample we would determine the lead, lime, sulphuric acid, carbonic acid, loss on ignition, the portion soluble in water, and the lime or sulphuric acid in that portion, calculating to sulphate of lime. Deduct the lime in the sulphate of lime from the total lime, and calculate the remainder to carbonate of lime; 368 CHEMISTRY AND TECHNOLOGY OF PAINTS | deduct the carbonic acid in the carbonate of lime from the total carbonic acid, and calculate the remainder to white lead; deduct the sulphuric acid in the sulphate of lime from the total sulphuric acid, and calculate the remainder to sulphate of lead. The lead unaccounted for as sulphate or white lead is present as oxid of lead. Deduct the carbonic acid and water in the carbonate of lime and white lead from the loss on ignition, the re- mainder being the water of hydration of the sulphate of lime. “Sample 8 contains as insoluble matter, barytes, China clay and silica. “After igniting and weighing the insoluble matter, carbonate of soda is added to it, and the mixture fused. The fused mass is treated with water, and the insoluble portion filtered off and washed. This insoluble portion is dissolved in dilute hydrochloric acid, and the barium present precipitated with sulphuric acid in excess. The barium sulphate is filtered out, ignited, weighed, and if this weight does not differ materially —say by 2 per cent, from the weight of the total insoluble matter, the total insoluble matter is reported as barytes. If the difference is greater than this, add the filtrate from the barium sulphate precipitate to the water-soluble portion of fusion. Evaporate and determine the silica and the alumina in the regular way. Calculate the alumina to China clay on the arbitrary formula 2Si0,. Al,O;. 2H.O, and deduct the silica in it from the total silica, reporting the latter in a free state. It is to be borne in mind that China clay gives a loss of about 13 per cent on ignition, which must be allowed for. China clay is but slightly used in white paints as compared with barytes and silica.”’ ‘““Sample g contains sulphide of zinc. ANALYSIS OF PAINT MATERIALS 3C€9 “Samples of this character are usually mixtures in varying proportions of barium sulphate, sulphide of zinc, and oxid of zinc. Determine barytes as matter insolu- ble in nitric acid, the total zinc as in Case 1, and the zinc soluble in acetic acid, which is oxid of zinc. Calculate the zinc insoluble in acetic acid to sulphide.” ‘Sample to contains sulphite of lead. “This is of rare occurrence. Sulphite of lead is in- soluble in ammonium acetate, and may be filtered out and weighed as such. It is apt on exposure to the air in the moist state to become oxidized to sulphate of lead. ‘There are certain positions which the chemist must take in reporting analyses of white paints: “First. White lead is not uniformly of the composition usually given as theoretical 2PbCO; Pb(OH)., but in reporting we must accept this as the basis of calculating results, unless it is demonstrated that the composition of the white lead is very abnormal. “Second. In reporting oxid of lead present this should not be done except in the presence of sulphate of lead, and if white lead is present, then only where the oxid is more than 1 per cent; otherwise calculate all the lead soluble in acetic acid to white lead. “Third. China clay is to be calculated to the arbi- trary formula given. “In outlining the above methods we have in mind many samples that we have analyzed, and the combinations we have chosen are those we have actually found present.”’ ANALYSIS OF PAINTS Separation of Pigment from Vehicle.—The can of paint is weighed off and if free from water, heated on the steam bath for 15 to 30 minutes. Owing to the marked decrease in the specific gravity and the viscosity of the paint 370 CHEMISTRY AND TECHNOLOGY OF PAINTS vehicle at the higher temperature, the pigment generally settles to the bottom very quickly. In the case of paints which show the presence of water, it is best to allow the pigment to settle out in the cold in order to avoid any saponifying action which the pigment might exert on the vehicles) [nesciear liquid is then drawn off as far as possible and set aside for analysis. The can is carefully wiped and weighed again. About 25 g. of the residue in the can are weighed into a tall weighing tube. A mixture of benzol and alcohol 1:1 is added and the contents carefully stirred up with a glass rod. Another tube containing a similar weighed quantity of the same material is balanced to within o.1 of a gram against the first tube, after adding the solvent and stirring. 3 The two are then placed in the opposite receivers of a centrifuge and whirled at a moderate or high speed, (depending upon the facility with which the pigment set- tles out) for about five or ten minutes. The clear liquid is then drawn off, the tubes balanced, and after the addition of fresh solvent, stirred and again centrifuged. This is continued until no more of the vehicle can be extracted. The tubes are then placed in an air oven first at 80° C. and then at 100° C. until dry. From the weights of the tubes before and after extraction, the weight of paint extracted, and the weights of the can with and without the supernatant liquid, the percentage of vehicle and pigment can be calculated. There is generally left with the extracted pigment a small percentage of unextracted matter (probably soaps resulting from the interaction of pigment and vehicle, or linoxyn), for which allowance must be made. wNALY SES’ OF “PAINT MATERIALS ie The extracted pigment is analyzed as outlined in the chapter on “Methods of Analysis of Pigments.” Determination of Volatile Matter.'—Weigh off into a round bottomed flask, 50 to 75 g. of the ready mixed paint. Connect with a condenser by means of a steam trap. Pass live steam through until no more of the volatile oil comes over. Allow the distillate to separate from the water and analyze separately. Shut off the steam and drive air through the apparatus. At the same time, heat the contents of the flask to 130° C. The residue is analyzed for non-volatile oils. Acetone, if present, will be: found in the aqueous as well as oily layers of the distillate. Analysis of Non-volatile Portion Extracted from the Ready Mixed Paint, as Previously Ouilined.—As a rule, very little information can be obtained, in the present state of our knowledge of this subject, from the analysis of a varnish or the non-volatile portions of a paint vehicle. Most of the constants or characteristics of the various ingredients which go to make up the varnish are so altered in the process of cooking that it is often extremely difficult, if not impossible, to distinguish them in the final material. Rosin can generally be determined qualitatively and quite often, quantitatively, but even here it is some- times impossible to detect it in admixture with other varnish resins. DETERMINATION OF ROSIN (Twitchell Method) ” Fatty or aliphatic acids are converted into ethyl esters when acted upon by hydrochloric acid gas in their 1 Amer. Soc. Testing Mat. Report of Comm. on Preservative Coatings for Structural Materials, 1903-1913. *}- Soc..Chem., Ind: 1891,10,,804- 3712 CHEMISTRY AND TECHNOLOGY OF PAINTS alcoholic solution; rosin acids undergo little or no change, abietic acid separating from the solution. Weigh off 2 to 3 g. of the mixed fatty or rosin acids in a flask, dissolve in 10 volumes of absolute alcohol and pass a current of dry, hydrochloric acid gas through the solution, the flask being kept cool by immersion in cold water. After about 45 minutes the reaction is complete, when unabsorbed HCl gas escapes. The flask is allowed to stand for one hour to permit complete esterification and separation of the ethyl esters and rosin acids. Dilute the contents of the flask with five times its volume of water and boil until the aqueous solution has become clear. Gravimetric Method.— Mix the contents of the flask with a little petroleum ether (b.p. below 80°) and trans- fer to a separatory funnel. The flask is washed out with the same solvent. The petroleum ether layer should be about 50 c.c. in volume. } After shaking, the acid solution is removed, the petroleum ether layer washed once with water, then treated in the same funnel with 45 c.c. N/5 KOH and 5 c.c. of alcohol. The liquids in the funnel then separate into: 1° a petroleum ether solution floating on top, and 2° an aqueous solution containing rosin soap. The soap solution is run off, the rosin esters liberated by decomposition with dilute hydrochloric acid, dissolved in ether, and separated by evaporating the solvent on the steam bath. : Volumetric Method.—The acidified mixture is poured into a separatory funnel and the flask washed a few times with ether. The mixture is thoroughly agitated, then allowed to separate, the acid layer run out, and the remaining ethereal solution containing the mixed ethyl esters and rosin acids washed with water until free from ANALYSIS OF PAINT MATERIALS Bie hydrochloric acid. 50 c.c of alcohol is then added and the solution titrated with standard alkali, using phenolphthalein as indicator. ‘The rosin acids react immediately, forming rosin soaps; the ethyl esters remain unaffected. The number of c.c. of N alkali is multiplied by 0.346, giving the amount of rosin acids in the sample. The gravimetric method is the more accurate one, due to the difference in combining weights of the rosin acids in different samples of rosin. The results obtained by the Twitchell method are only approximately accurate. In the case of a mixture of rosin acids, fatty and un- saponifiable, saponify with alcoholic KOH and drive off the alcohol (after dilution with water) by continued boiling. Disregarding the undissolved unsaponifiable, the aqueous soap solution is transferred to a separatory funnel and shaken out with petroleum ether; this removes the unsaponifiable. On treating with mineral acids, the soap solution yields a mixture of rosin and fatty acids which are separated by the Twitchell process. In the volumetric method, the unsaponifiable need not be separated as above. 2 g. of the mixed acids and unsaponifiable are weighed off accurately, titrated with N alkali and the number of c.c. (a) noted. Another 2 g. are treated with HCl gas and titrated with N alkah, using (b) c.c.; taking 346 as the combining weight for rosin and 275 for the fatty acids (palmitic, stearic and oleic), the weight of the rosin acids is b X 0.346; the weight of fatty acids is (a — b) X 0.275, and the weight of the un- saponifiable equals roo — {b Xo0.346 + (a— b) X 0.275}. Separation of Rosin Acids from Faity.— After the esterification process, we get a mixture of free acid and esters, and after titration (e.g. in the volumetric process) we get a mixture of rosin soap and ethyl esters of fatty acids. If the alcohol is distilled off and the remaining 374 CHEMISTRY AND TECHNOLOGY OF PAINTS mixture treated with water, the soap is dissolved, leaving the esters floating on top of the soap solution. The two layers are separated and the soap solution, after washing with ether to remove traces of esters, yields rosin acids on acidulating. The ethyl esters are saponi- fied by caustic alkali and the fatty acids separated. DETERMINATION OF ROSIN (Wolff & Scholze Method) * Quick Titrimetric Determination.—2 to 5 g. of the rosin — fatty — acid mixture, according to the quantity weighed off, are dissolved in to to 20 c.c. of absolute methyl or ethyl alcohol, treated with 5 to to c.c. of a solution of one part of sulphuric acid in four parts alcohol (methyl or ethyl) and boiled for two minutes with reflux condenser. The reaction liquid is then treated with 5 to 10 volumes of 7 to ro per cent sodium chloride solution and the fatty acid esters together with the rosin acids extracted with ether or a mixture of ether and a little petroleum ether. The aqueous solution is drawn off and agitated once or twice with ether. The ethereal solutions are united, washed twice with dilute sodium chloride solution (or when the washed water is not neutral, to neutrality), and after the addition of alcohol, titrated with N/2 KOH. Assuming an average of 160 as the acid value of the rosin acids and a correction for unsaponifiable fatty acids of 1.5, and further taking “m”’ as the amount of the weighed fatty —acid—rosin mixture and “a” as the number of c.c. of KOH used for neutralization, we obtain as the rosin acid content in per cent, the following: Bt fee 70 hae 1 Chem. Ztg. 38 (1914), 369, 382. ANALYSIS OF PAINT MATERIALS 375 The amount of rosin is approximately obtained by multiplying this value by 1.07. Gravimetric.—2 to 5 g. of the fatty acid mixture are treated as in the first method. After neutraliza- fen 8to..2. cic. more of alcoholic-KOH are added and the ethereal solution repeatedly washed with water. The wash water and soap solution are concentrated to a small volume, transferred to a separatory funnel, acidi- fied, and after the addition of the same amount of sodium chloride solution, extracted two to three times. The ethereal solution is dried with fused sodium sulphate and the ether distilled off in-a small flask. The residue on cooling is dissolved in 10 c.c. of absolute ethyl alcohol, and 5 c.c. of a mixture of 1 part sulphuric acid with o.4 parts alcohol are added. The mixture is ,allowed to stand: for 15 to 2 hours at room temperature. It is then treated with 7 to ro volumes of to per cent sodium chloride solution, extracted with ether two to three times, and the united ether extracts (after twice washing with dilute sodium chloride and drying with fused sodium sulphate) distilled off. The percentage of the thus isolated rosin acids may be multiplied by 1.07 in order to yield approximately the rosin content. ROSIN AND RosIN OILS Liebermann-Storch Reaction.— Dissolve the washed and dried mixed acids (obtained by saponification of the material to be analyzed and liberating the acids with dilute hydrochloric or sulphuric acid) in acetic anhydride on the water bath, cool and add a few drops of sulphuric acid (specific gravity 1.53). This acid is made by mixing 34.7 c.c. of concentrated sulphuric acid with 35.7 c.c. of water, yielding 62.53 376 CHEMISTRY AND TECHNOLOGY OF PAINS per cent sulphuric acid. The presence of rosin or rosin oil is detected by a very fine reddish violet coloration produced on the addition of the acid. Detection.— Rosin oil may be detected by the Lie- bermann-Storch reaction already mentioned, or by the following: ! Stannic bromide is prepared by adding bromine drop- wise to granulated tin in a dry flask immersed in cold water until an excess is present. Then a little more bromine is added and the whole diluted with three to four volumes of carbon disulphide. The reagent thus obtained is stable. To carry out the test, a few drops of the rosin oil are placed in a dry test tube and dissolved in 1 c.c. of car- bon disulphide. Add the stannic bromide reagent grad- ually. If rosin oil is present, the liquid assumes an intense, brilliant, violet coloration. It may be necessary to dilute with more carbon disul- phide in order to bring out this color. On standing, a violet sediment is formed in the tube from which, after removing the liquid and warming the residue with carbon disulphide, the purple coloration is again obtained free from impurities. In the presence of much mineral oil, mix the sample with the solution of stannic bromide in carbon disulphide, and then add, drop by drop, a solution of bromine and carbon disulphide. This yields the coloration unmasked by any due to the mineral oil. Rosin OIL Rosin Spirit.— This is the lighter and more volatile portion obtained in the dry distillation of rosin. It is separated from the aqueous acetic acid layer, purified with 1 Allen, “ Commercial Organic Analysis.” ANALYSIS OF PAINT MATERIALS a7 sulphuric acid and caustic soda, and then re-distilled. It is insoluble in water or alcohol, but soluble, in all pro- portions, in ether, petroleum-ether and turpentine. The specific gravity varies from 0.856 to 0.883. Composition. — The hydro-carbons,! of which this is principally composed, include pentane and pentene and their homologues, toluene and its homologues, tetra and hexahydrotoluene and their homologues, terpenes, etc. The characteristic constituent of rosin spirit is hep- tine, C;Hi», (methyl-propyl-allene). The compound boils atetos to moA~ CG. and has a specific gravity. of 0.8031 at 20° C. It is soluble in alcohol and ether, absorbs oxygen very readily, but does not affect ammoniacal cuprous chloride or silver nitrate. Rosin Oil.—This is the heavier and less volatile por- tion obtained after the rosin spirit has been collected. It generally has a strong fluorescence although the lat- ter can be more or less destroyed by hydrogen peroxid, the addition of nitro-benzol, nitro- or dinitrotoluene, dinitronaphthalene, or by heating with sulphur. The specific gravity of the crude rosin oil varies from 0.96 to 1.1 while the refined generally has a specific gravity of 0.97 to 0.99. DETERMINATION OF WATER Qualitative. — Water in an oil, paint, dryer or varnish may be detected by adding a few c.c. of dry mineral oil to an equal quantity of the sample in a test tube and shaking vigorously with a few grains of a strong dye like erythrosine, rhodamine or methylene blue. Coloration proves the presence of water. Solvents like alcohol, acetone or amyl acetate which dissolve these dyes must of course be absent. 1 Renard, Amer. Chem. Phys. 1884 (6) 1, 323. 278 CHEMISTRY AND TECHNOLOGY OF PAINTS The presence of an appreciable quantity of water in an oi is indicated by the crackling produced when some of it is heated in a test tube beyond 212° F. Quantitative. —(1) In the case of non-volatile oils, about 5g. are accurately weighed into a small evaporating dish or watch-glass and dried in the air oven at 1oo-110° C. for two hours. The loss in weight (except where volatile fatty acids are present) is reported as moisture. | For accurate determinations, however, the above method is open to serious objection. In the case of soya bean oil, for example, owing to its comparatively high content of volatile acids and glycerides, the results obtained may be somewhat high; whereas in the case of linseed oil the loss due to moisture may be more than counter-balanced by the gain in weight due to oxidation. With drying oils, the following method! is therefore recommended: (2) A small Erlenmeyer flask fitted with a cork through which pass two tubes, a long tube reaching down to the bottom of the flask and a short one ending just below the cork, is carefully dried and weighed. 5 g. of oil are then introduced, the flask placed upon a steam bath, and dry carbon dioxid, hydrogen or coal-gas passed through the oil for 1 or 2 hours by connecting the short tube to an air pump or aspirator. The flask is then carefully dried and weighed. (3) For the determination of water in oils like pine oil, which always contain an appreciable quantity of water, as well as in ready mixed paints, the method? outlined on the next page is very useful: 1 Determination of moisture in oils in a current of air—Son- nenschein-Zeit. anal. Chem. 25, 373. J. soc. Chenmiindiean. ae 508. 2° Michel, ;ChemyZitegsigis se. ANALYSIS OF PAINT MATERIALS 379 The substance containing water is distilled in an inert, water- insoluble medium, lighter than water and having a higher boiling point. For this purpose a mixture of toluene and xylene (1:2) is found most suitable. On condensing the water separates quanti- tatively from the toluene-xylene mixture. 150 c.c. of a dry mixture of 3 pure toluene (b. p. 110° to 112° C.) and % commercial, pure xylene are placed in a 300 c.c. Jena flask, and the substance to be examined added. It is well to add a small spiral of aluminium to produce uniform ebullition. The distillate is col- lected in a separatory funnel about 10 cm. in diameter, and provided with a glass cock having a bore of at least 5 mm. A to c.c. tube, graduated in 0.1 or 0.05 c.c., in which the water is collected is at- tached. The distillate, which is milky in appearance on account of suspended water, is best separated by centrifuging. The amount of water is then read off on the graduated tube. The toluene-xylene may be dried over calcium chloride and used again. (4) Determination of water by means of calcium carbide (see U. S. Circular No. 97, of the Bureau of Chemistry). ANALYSIS OF OILS Spec Gravity.— This is determined at 15.5° C. (60° F.). For most technical purposes the hydrometer is universally used. Where, however, a greater degree of accuracy is desired or where the amount of oil available is rather small, the Westphal or Mohr’s balance, the specific gravity bottle, Sprengel’s picnometer or finally the analytical balance may be used. In the latter case the specific gravity is determined by means of a plummet suspended from one of the balance beams and immersed in the oil maintained at 15.5°C. The latter is contained in a beaker or short cylinder placed -upon a bridge so as not to interfere with the balance pans. If the plummet weighs in air a grams, in water w grams, and in the oil at 15.5° C. 0 grams, 380 CHEMISTRY AND TECHNOLOGY OF PAINTS a—w = loss in weight of plummet when immersed in water = weight of vol. of water equal to vol. of plummet a—o = wt. of vol. of oil equal to vol. of plummet a— 0 Wop Pee of oil For the determination of the specific gravity of viscous oils Lewkowitsch mentions the use of Bruhl’s picnometer. Eichhorn’s araeopicnometer is used in the case of very small quantities of oil. In the latter case also the specific gravity of the oil may be obtained by preparing a mixture of alcohol and water so that a drop of the oil remains in suspension wherever it is placed in the mixture. ‘The sp. gr. of the alcohol-water mixture is then determined by means of a hydrometer. It is advisable to determine the specific gravity at 15.5. C. Where, however, this is not feasible a correc- tion! must be made. This has been found by Allen to be approximately the same for most vegetable and hydro- carbon oils, and is equal to 0.00064 for 1° C. or 0.00035 fore ks ; Saponification Value.— This expresses the number of mgms. of potassium hydroxid necessary to completely saponify the glycerides and fatty acids in 1 g. of oil. Weigh off in a 200 c.c. Erlenmeyer flask about 2 g. of oil, add 25 c.c. (from a pipette) of N/2 alcoholic potash, and heat on the steam bath for 4 to 1 hour with reflux condenser. ‘The contents of the flask should boil gently, and should be agitated occasionally. When saponification is complete, cool, add 5 drops of 1 per cent phenolphthalein solution, and titrate the excess of alkali with N/2 hydro- chloric acid solution. A blank titration is made with 1 Allen, Comm. Org. Anal. 1910, Vol. 2, pp. 49-51. ANALYSIS OF PAINT MATERIALS 381 25 c.c. N/2 alcoholic potash which has been heated as outlined above. The difference between the two titra- tions shows the number of c.c. of N/2 HCl equivalent to the KOH required to saponify the oil. The alcoholic potash must be prepared from pure grain alcohol (95 per cent) and chemically pure caustic potash. Dissolve 40 g. of the stick potash in about 25 c.c. of water and dilute with alcohol to 1 liter. After standing for one day the solution may be filtered from the precipi- tated potassium carbonate (which the stick potash always contains) and set aside in a uniformly cool place. The saponification value of an oil is valuable as a cri- terion of its freedom from adulteration with mineral oils. It does not, however, assist in detecting adulteration with other vegetable oils, since most of the naturally occurring vegetable oils have saponification values which vary be- tween rather narrow limits. (See table, page 388.) Acid Value.—This expresses the number of mgms. of potassium hydroxid necessary to neutralize the free fatty acids in 1 g. of oil. Weigh off 5 to 15 g. of oil in an Erlenmeyer flask, add 50 c.c. of alcohol, amyl alcohol, or ether-alcohol mixture (1:1), add 2 to 3 drops of phenolphthalein and titrate against N/10 or N/5 caustic potash or soda. Of the above solvents amyl alcohol and ether-alcohol dis- solve most oils and resins almost completely. They are especially valuable in the case of viscous oils. Where alcohol alone is used it is generally best to heat it with the oil for a short time on the steam bath before titrating in order to completely extract the free fatty acids. ‘Titrate cold. In the case of resins, and especially fossil resins, the method must be modified somewhat. Dissolve about 1 g. of the sample in 50 c.¢. of a mixture of absolute alcohol 382 CHEMISTRY AND TECHNOLOGY OF PAINTS and benzol (1:1) or a similar mixture of alcohol and ether by boiling, with reflux condenser, on the steam bath. Titrate against N/2 or N/s5 alcoholic alkali. It has been found in this laboratory that aqueous alkali yields acid values much higher than those obtained with alcoholic alkali. Oils which have been thickened by blowing generally have a lower acid value. On the other hand we have found that boiled bodied oils show a fair content of free fatty acids. Same Oil Boiled Varnish Oil and Bodied Sp. gr. 0.933 0.973 Acid. Val. Ret 14.8 Sapon. Val. 194.2 194.2 Iodine Val. 193.2 Ones Iodine Value.— This figure represents the percentage of iodine chloride (expressed in terms of iodine) absorbed by the unsaturated glycerides and acids in 1 g. of oil. Hiibl Method.— About 0.15 g. of drying oil, 0.25 g. of semi-drying oil or 1 g. of non-drying oil is weighed off in a capsule, placed in a 500. to 1,000 c.c. glass-stoppered bottle, and dissolved in ro c.c. of chloroform or carbon tetrachloride. 25 c.c. of mercury iodochloride prepared as shown below are added from a pipette. Empty the ‘pipette each time in exactly the same way, draining until one or two drops have fallen. Moisten the glass stop- per with potassium iodide solution, and set the bottle aside in the dark. If after two hours the color of the solution in the bottle is not a deep brownish red, add another 25 c.c. of mercury solution. When the reaction is complete the solution should contain an excess of iodine at least equal to the amount absorbed. For semi-drying oils allow 8 hours for complete absorption ANALYSIS G# PAINT MATERIALS 383 of the iodine; for drying oils allow 18 hours. 15 c.c. of 10 per cent potassium iodide solution (or more in case a red ppt. of mercuric iodide is formed) are added, and the contents of the flask diluted to about 500 c.c., at the same time washing in any volatilized iodine trapped by the potassium iodide solution on the stopper. The excess 10dine in the aqueous and chloroformic layers is titrated against N/1o sodium thiosulphate with frequent agitation until the color of both layers is but faintly yellow. A few c.c. of freshly prepared starch solution are then added, and the titration continued until the blue color is discharged. A blank containing exactly the same quantities of solvent and mercury iodochloride solution must be set aside along with the oil, and then titrated after the addition of the same quantity of potas- sium iodide and water. The difference between the number of c.c. of sodium thiosulphate required to neutralize the free iodine in the blank and the excess iodine with the oil represents the amount of iodine absorbed by the oil; from the latter the iodine value can be calculated. To prepare the mercury iodochloride solution (1) 25 g. of pure resublimed iodine are dissolved in 500 c.c. of pure alcohol; (2) 30 g. of mercuric chloride are dis- solved in the same quantity of alcohol in another bottle. On mixing the above two solutions and ailowing to stand for 12 to 24 hours a solution of mercury todochloride is formed containing 1 molecule of iodine (I,) to one mole- cule of HgCl.. The mixed solution cannot be used for _making iodine value determinations when it is older than 24 hours. However, the two solutions in themselves will keep indefinitely. It is therefore best to prepare only as much iodochloride solution as is required. The sodium thiosulphate solution is made by dis- 384 CHEMISTRY AND TECHNOLOGY OF PAINTS solving 25 g. of the crystals in 1,000 c.c. of ‘water. It may be standardized by either of the following methods: (a) Against Potassium Permanganate Dissolve 1 or 2 g. of pure,potassium iodide in a 400 c.c. flask, using a small amount of water; add 5 c.c. of hydrochloric acid (1:1) and then 20 or 25) cle, of sau accurately standardized N//10 potassium permanganate solution; the liberated iodine is titrated with the sodium thiosulphate solution after diluting to 200 cc. The reaction involved is indicated below: 2K MnO,+ 10oKI1+ 16HCl = 12K Cl + 2MnCl, + §H,0— Tor, (b) Against Potassium Dichromaie K,Cr.0;-+ 6KI-+14HCl = 8KCl+ 2CrCh,+ 7H,0 + 61 Weigh off accurately 3.8633 g. of pure potassium dichromate and dissolve in exactly 1,000 c.c. of water. This quantity of dichromate solution is equivalent to exactly 10 g. of iodine liberated according to the above equation. In a 600 c.c. Erlenmeyer flask place to c.c. of ro per cent potassium iodide solution and 5 c.c. of hydrochloric acid (1:1), and add exactly 20 c.c. of ,the dichromate solution from a burette. Dilute to 300-400 c.c. and titrate against sodium thiosulphate after adding starch solution. The end point is indicated by a change in the color of the solution from deep blue to pale green. The starch solution is best prepared, as needed, by shaking up about 0.5 g. starch with 50 c.c. of water, heating, and boiling for 1 or 2 minutes. The solution should be cooled before being used. The dichromate solution keeps indefinitely and may be used for stand- ardizing the thiosulphate solution, the strength of which varies slightly with age. ANALYSIS OF PAINT MATERIALS 385 Wys Method.— Dissolve 13 g. of iodine in glacial acetic acid, and determine accurately the amount of lodine present, using 25 c.c. for the determination. Then pass dry chlorine gas into the solution until the color changes suddenly from deep reddish brown to pale yellow, due to the complete transformation of the iodine into iodine chloride. The iodine equivalent of this solution must be exactly twice that of the original iodine solution. If a titration shows more than double the iodine equiva- lent, there is an excess of chlorine and enough iodine should be added to combine with it. If the analysis shows less than double the amount of iodine there is still an excess of iodine and more chlorine should be added. The iodine value determination is carried out exactly as in the case of the Hiibl method; the time of absorp- tion, however, is very much less, being 4 hour for non- drying oils, t hour for semi-drying oils, and 2 to 6 hours for drying oils and marine animal oils. According to Allen, absorption in the case of oils of low iodine value is complete in 4 minutes, while those of higher value require not more than 10 minutes, provided too much oil is not taken. In this laboratory we have made it a practice to allow about 1 hour for semi-drying and drying oils. The values obtained by the Wijs method are as accurate as those obtained by the Hiibl method, and agree very closely with the latter. BROMIDE TEST It has been found! that on treating the ethereal solutions of certain oils with a slight excess of bromine, an insoluble precipitate is obtained. 1 Hehner & Mitchell, Analyst, 1898, 23, 313. 8 ie 386 CHEMISTRY AND TECHNOLOGY OF PAINTS Method. — Dissolve 1 or 2 g. of oil in 4o c.c. of ether, add a few c.c. of glacial acetic acid (the precipi- tate formed with bromine is more granular when the acid is used), stopper the flask, and cool to 5° C. Add bromine, drop by drop, from a very fine pipette until the brown coloration persists. The temperature must not be allowed to rise. Allow to stand for 3 hours at 5° C., filter (preferably by suction), and wash four times with ice-cold ether. The residue is dried in the water oven and weighed. The insoluble bromides obtained from linseed oil melt at 140 to 145° C. and contain about 56 per cent bromine. Those obtained from marine animal oils decompose be- fore melting. This property, therefore, furnishes a good method of detecting small amounts of the latter in linseed oil. The bromide test is useful in the examination of boiled and bodied oils. Lewkowitsch' has found that the process of boiling linseed oil decreases the yield of insoluble bromides. On the other hand, an oil which has been bodied by blowing at a low temperature will give as high a yield of bromides.as the oil from which it is prepared. Lewkowitsch recommends that the mixed fatty acids, carefully prepared in an atmosphere of carbon dioxid or hydrogen, be used in making the bromide test. The precipitate then obtained is much easier to filter than when the oil is used. According to Eibner and Muggenthaler,? the bromide test is carried out as follows: 2 g. of the mixed fatty acids are dissolved in 20 c.c. of dry ether, and cooled to minus 10° C.; 0.5 c.c. 1 Farben(Ztg., 1012aac: 2 Muggenthaler, Inaug. Dissert., r912, Augsburg. ANALYSIS OF PAINT MATERIALS 387 of bromine are added, drop by drop, from a very fine pipette, allowing about 20 minutes for the addition of this amount of bromine. Another 0.5 c.c. of bromine are then added in to minutes’ time. The temperature must not go beyond — 5° C. The flask is corked and set aside for 2 hours at — 10° C. The solution is then filtered through a weighed asbestos filter, and washed 5 times with dry ice cold ether, using 5 c.c. each time. The precipitate is then dried for 2 hours at 80 to 85° and cooled in a dessicator. HEXABROMIDES BY THE ABOVE METHOD Fatty Acids from Per Cent An a la Fi se gs cao A os 64.12 Seineee il baltic) eee. cw oe. 57.96 Pipceen Ole DUtCR) vow is has eh Brig, Persea Oil a Plata) 2. Sy, on wn 51.66 ree IL Vall ohn ss steak S050 CLINT: BRED REY RIEL es ea oo aa nil Soya Bean Giles ye heed ido ce. Lalu ers Peep emee dle: or Ih ce 60 = I0r4 2 ounces oO 54 ce (7 ce “cc (79 “ee fe) = 116 2 ‘ ce me, 3 (79 ce “cc . ce 43 ce . 6c S 7352 (a4 (a9 7 ce “c 3? ce ° = F521 I 21 eh (9 we eae (a9 ce : (79 (79 Io 6c“ 1000 a = 1 liter = 34 fluid ounces nearly, or 2} pints. THE CONVERSION OF FRENCH (METRIC) INTO ENGLISH WEIGHT The following table, which contains no error greater than one-tenth of a grain, will suffice for most practical purposes: Igram = 15% grains. 2-prains = > 405 73" 3 a3 ay 464 ce y eae et WE coe Oe eee ele) > or «tdram_ 1# grain. RE crs Pe ee ee EY ey led BE ett fo ogo Serer She te: eerie See (CDG eee y Seon we sah Pee pee ele re “2 a ae “ Bo SE ree a 9 Bie aes arene ce “99 drams 732 : Oe csi ae RRB esate eh ae Me Ye tse ey TO. 2." p wee LAS eae re eee ae es! TE. 2s Seh60 £ an eae (S - By RS ays aeee 12-2 3. ols. TBS ars Se eres ee eee te 13 Sk pe AO0F tae ee eee ea C4 \ a ae 14 42st see" Area 8 gle eee 3 15 Scar Be oO anes Sere ¢ (250 \oes Lee 16 ‘< = 247 HO AY Se Aes « 4 ““ 7 6c Ty: < Site Ace PG ae teu ie ohana eee Weg e 8 T°): OE: Wee NS ak eae ete A ea ee ca memes 1 os ““ % 3085 ia eae “< 5 é< i “ 3 ce a 4 3 ig ee a «6 7 iz 43 | ce 40 me: JOLY eit) aah ae eh 10 17$ 56. Be Ae 77 ene biel 12) Sees he 60° = 26 S. fike APiyaee eit a Le eee " 70: Mit OSOE hae s ae renee 160) eee fe er LY MM RR A | 20") eae eae go. “= 1389 Tepito ee east tacy 9 . T0048)! 4 PL 4a Aer ee ae ae ps ES aks ae 1000 = 1 kilogram = 32 02,, 1 dr., 12¢ gr. ANALYSIS OF PAINT MATERIALS 395 Metric SYSTEM OF WEIGHTS AND MEASURES Measures of Length Denominations and Values Equivalents in Use MVliy GIS MECOR eels aches Ale es ole wees 10,000 meters. 6.2137 miles. Relomener de ita Slums ches I,000 meters. .62137 mile, or 3,280 ft. ro ins. PIECLOMELEEA tes 6 ste P's, Swiss + roo meters. 328. feet and 1 inch. WDekanmevenase ays ton aeke «oles Io meters. BORN inches. WATE: has Ne at an eer pO I meter. 200871 inches. ID ECINOECI Wier eels faces es ishe aig hia ce 1-roth of a meter. 3-937 inches. Centiinetenat 2s. asa. 23% ee 1-rooth of a meter. .3937 Inch. MUlliiMeberttuioe a> so. Wes aos toes 1-rocoth of a meter. .0394 inch. Measures of Surface Denominations and Values Equivalents in Use [Seeing 135.3 Seon, 8 Ue cae eee eee 10,000 square meters. 2.471 acres. Ge Ba ere Go Ba Oe ee 100 square meters. 119.6 square yards. CSS ORE 3 OO Oe I square meter. 1,550. square inches. Measures of Volume Denominations and Values Equivalents in Use N ee Cubic M M i ames Livers ubic Measures Dry Measure Wine Measure Kiloliter or stere.}| 1,000 t cubic meter. 1.308 cubic yards. 264.17 gallons. Hectoliter...... 100 | 1-roth cubic meter. 2 bu. and 3.35 pecks.} 26.417 gallons. Dekaliter....... Io ro cubic decimeters. g.08 quarts. 2.6417 gallons. 1 ihe) ees eee I t cubic decimeter. .908 quart. | 1.0567 quarts. Deciliter.......| 1-10 | 1-roth cubic decimeter. 6.1023 cubic inches. .845 gill. Centiltter......;| 1-100 10 cubic centimeters. .6102 cubic inch. .338 fluid oz- Milliliter....... I-1000 1 cubic centimeter. .o61 cubic inch. 27 9 fled 3 Weights Denominations and Values Equivalents in Use ee Number of Weight of Volume of Water Avoirdupois : Grams at its Maximum Density Weight Millier or Monneaw.... oa8. he8- 0 1,000,000 I cubic meter. 2204.6 pounds. MUTE SL hee ee a PSR yen’ sie 6 100,000 r hectoliter. 220.46 pounds. jc Ggase' He biol =: Sone ene ao 10,000 ro liters. 22.046 pounds. Bevloeramivar mail ascii 0. sho ee 1,000 r liter. 2.2046 pounds. PLECEORMAI Gees er niers Si eGue ental I0O I deciliter. ; 3.5274 ounces. WGA rane ea a leyals, panies so cote Io Io cubic centimeters. -3527 ounce. Oeil pen acme ere avs Cheon Nae ae it 1 cubic centimeter. I5.432 grains. Weisner Selene oa I-10 r-roth of a cubic centimeter. I. 5432 grains. (CEN EIS CE col Giiee, Naren hae lara I-100 to cubic millimeters. .1543 grain. A indll bad anaes oe Meee ieee gee eae ae I-1000 1 cubic millimeter. .O154 grain. For measuring surfaces, the square dekameter is used under the term of ARE; the hectare, or 100 ares, is equal to about 24 acres. The unit of capacity is the cubic decimeter or LITER, and the series of measures is formed in the same way as in the case of the table of lengths. The cubic meter is the unit of measure for solid bodies, and is termed STERE. The unit of weight is the GRAM, which is the weight of one cubic centimeter of pure water weighed in a vacuum at the temperature of 4 deg. Cent. or 39.2 deg. Fahr., which is about its temperature of maximum density. In practice, the term oe centimeter, abbreviated c.c., is generally used instead of milliliter, and cubic meter instead of lloliter. 306 CHEMISTRY AND TECHNOLOGY OF PAINTS SPECIFIC GRAVITY OF VARIOUS MATERIALS AceUCAC epcew Sone ae 1.0607 3 A CELOHE Were iste oe te .788-.790 Acetylene 0004. tek .Q2 ACEC ACIGits sam aier 1.0621 4 Agaté= a ve nee. eee oe 2.5-2. a Alabaster ttc. see 2.3-2.8 Aluminium, Oxides 35200. 3:75-3:00 ir Sulphate..... 2d r “ 18H2O 1.62 Ahim,-Potassium, ose Las aS SS SOGH an er een ee 1.65 ‘¢ Ammon. Chrome. .1.719 ‘‘ Potass. Chrome. . .1.81278 (0. °) A mDeELa) apie a tase 1,0=1.1 Ammonia*(eae)ee. 0. & O71 fe (liq.) .6234 (0.°) Ammonium Carbonate NH,HCOs. . 1.586 we Chloride... . 1.520 (17. 2 si Nitrate;..c. 2 1.725 (15. | Sulphate. . ..1.7687 %& ns “ “acid 1. 787 Amy]l ‘Acetate..... +2 38792'(20. ) Alcohol wees ee .8144—.8330 ‘““- Valerianate.._.icuw) oT2no.,) Anilin@eg. os eater 1.0276 (12.°) Anthracene = y.. Geo. ee 1.147 Anthracites.4 2. 2, shoe 1.4-1.7 Antimony Oxid) /Urixeesesc2 shay Tetra . .4.07 f jen eeDiasges: “8 runes 4.120 (0.°) “ec Arsenic Disulphide. . 2A=3.6 SPR RCNIORIC occur 3.990-4.25 ee FIX eae Ane 3.646 Asbestos; sateen ee t.4 Asphalt. se: ‘San Pen ae {i055 Barium Carbonate. .....4.27-4.37 ‘“‘ Chloride 2H20.. .3.007 7¢ leek CLOXIG 2 uy rae 4.958 ‘(etesulphide, ystae 4.25 : Sulphate; WG, 4.33-4.476 Barleyecat Got ee ae .51—.00 Barytes: ie . ena 4.476 Basalts\.3.44:n- a: Sa Diy—202 Bees Wax (see wax). Beefsuet jad Oe eG meee et ce Rie, ee Wace. S .968 Bellmetal 5 2. cote 8.81 Benzene b. p. 80.5° C.... .8799(20. ae: ) Benzoic Acid kek eae hae 1.201 (21. Blanc: Fixes at ee ae 4.02-4.53 Blue Vitrioly 7. .0weee 2.27 Bones oi... ce, See 1.7-2.0 BorieAcid: 4 4 ce eee 1.46 BuLteryo ten oes eee .865—.868 ButyricAcidina:, eae 9599 admium Sulphide (artif.). . . 3.9-4.8 C ““ (Greenockite) . 4.8-4. 9 Calcium Carbide aan 2523 Carbonate. . 2572-2205 - Chloride : H:0)r. 654 % . 2,26 “ Fluoride. . a a . Hydroxid. . ee <2. O7n “< Oxide ee 3.15—-3-40 - Sulphate. -%. += 2.904 o (Gypsum)...... 2.32 = Sulphide... 23.7 4.2.8 i Tungstates. = 6.062 Camphor. )..555se eee .992 Caoutchouc. 22... .92-.96 Carbolic AC.) sae 1.0597 (33. ) Carbon (Amorphous). . . .1.75—2.10 “¢ - .(Graphite).+.". .2.t0-2-505 “(Diamond eee 3:47-3-5585 “t= Diogid a ; ehee ty Disulphide. . 1.28 “< - Monoxid.32eeses 0.067 ‘“*. "Tetrachloridesy, 1-50 Cast Tron? yaaa wean Cellulose = 3455. aeeniee T.29=FA5 Charcoal (Airfilled). . 0.4 (Aintree eae cee 1.4-1.5 Chlorine? =: 2-222 eee 2.491 Chlorefotm33)5 ee 1.5204 Chrome Alum Cre(SQx)3. KySOxq. 24H2O a aeaces STEN 1.81278 Chromic Oxid;2aan sess Chromium. eae 6.92 Chromium Trioxid..... .2.67—2.82 Citric Acid 3 ake eee 1.542 Clay “7. 0 ae 3. eee Cobalt Chloridesaaae emer 2.04 Cobaltic Oxid (Co203) .. .4.81-5.6 Cocoabutter (m. p. 33. mas. 34. CG). : kau ee .89-.91 Copal, ... Sees eee 1.04-1.14 Copper é«.-: 3s eee 8.91-8.96 Copper Carbonate, Basic. 3.7—4.0 Cork. cs: Se eee 24 Corundum=. 2: 2 ee 4.0 Cottan.(Airdry ) eee 1.47-1.5 Cryolite AlF33NaF. 12.6 Cupric Hydroxidl ae 3.308 “<’ Oxid- (Black cae 3 32-6.43 ‘“< Subpha tess eee 25816 ‘“‘', Sulphate (5H.O),. 2.284 — _ “« _. -Sulphidevwes eee 3.8-4.16 Cuprous Oxid (Red) a. 5-75—0.09 Cymene b. p. 175.°-176.° 0.862 (20.°) Dextrin®. 2. 4) ee 1.0384 Diamond ’y, "22 3.40-3-52 Dolomite. cen: © see 2.9 ANALYSIS OF PAINT MATEIRALS SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued Earth: CAV EINE ess. se 1A Hecht Oe oe Regie int’ ES ee Oe naa ena 1.34 eURAD RV Gt NT ret a oe. os 1.6-140 Vert Si ieee er 1.036 Father (Diethyl)... 2. 0.7183 (17.°) penyl Acetate... 5. .8920-.9028 Ethyl Alcohol}... >... 7937 ty Pee Dee ee, .9784 Eeicalyptol.. > 2. Beane es ee (20. ) MIBENOL Gt oe oy SS. 0630 (18.°) Perro Chloride: a. 2.804 (10.8 ) Pe tA Varexid: s; . .4 s 63.4-3.0 OSI See es 5.12-5.24 Ferrous Carbonate... .. .3.70—3.87 ss sulphates::...... 1.86-1.90 Sulipmide.. f..7.. 4.75—-5.04 MASAI). 5 es 2: 5 LE 01S ie i ae eae 0.920-0.928 Formaldehyde (—20.°).... .8153 Formic Acid ieee ee I.219- 25° cL ee 1.244—0 PUA DICOA CIOL pee oe .cae 1.625 Purina eae 1.1504 -9 Gasoline (b. p. 70°.-90.°). .66-.69 Cres ALOR? a tak 1.88 Glass: WEINGOWs orc ok 2.6 BVEIE EOE Muerte. 5 sos Ac 272 eta ditt Ce ee ee 2.05 ‘UU Bee a Sits rapa Se a 250-5.9 CUD he aan ee a 1.27 DBS ee ie ee oo soil 2 A207 Rot amity. Sens Sk vin. 2 2.51=3.05 Graphite (Natural)...... 2.17—-2.32 (Artificial). .., .2.10-2.25 Sunenrate.. 0. aa: © 3i-1.45 rmbtapereiane oi 6a kw GOL Bec Mie eaonk ees 2639 Hemp (Airadry) 0. o.- res orableride 26 ty .5.253.0 hyveriodic AGid 4 Ss! 4.3737A Hydrobromic Acid...... 1.278A Hydrochloric Acid.......1.195 (8° m Hydrocyanic Acid....... .697 (18.°) Hydrofluoric Acid....... 9879 (15. ) TEV OR OCC a: Pa. de a .06949 Hydrogen-peroxid....... 1.4584 (0.°) Hydrogen-sulphide...... .g—1.1895 Tydroquinone.......... 1.326 Tacta RUbBEr 2. fos. 2 .93 MDW Oiad a erat ete ae 1.35 PBOIS ANC ater: tees Va 4.629 (0.°) 397 A Gee Nat Rb 69 ro r g R 4.948 (17.°) TOCOcOriie proc ciate wy 4.09 Tron USAT Res een ee tee 7.85-7.88 (gray pig).. Osyth 3 ‘(white pig). | .7.58-7.73 BPR CEUSE Jeter es a ac ng 204 Sa e(Wrousht) ke tachi ce, 7.00 fe STS TUn ante (Pak meeoa ieee 4.86-5.18 PES UIOKIC ap. teen mites ca2 LVORV are Me oe a 7 L.02-1.02 Japan Wax (m. p. 53.5°- _ BARS iti ang ees AS 992 FR 10) iar dens, atoagaas eke oe Bactie-Acdis coo. nete ae. 1.2485 Lard (m. p. 41.5-42.C.).. .92-.94 eiware sk setae rie eee ean 2.00-3.00 Lead (milled es 351.42 (wire)... “fs .11.28 “> Acetate. see oe & 2.50 co HAGAT DONATO Mare ne: 6.43 eS be , Basic. . .6.323-6.492 ev OTIC se. oacst 5.8 Mey TOMLAL over e cere aye e G@isscas “* Hydroxid (3PDOHsO) «.., 1... 7.502 Se OCHCLE ree rte hrs," 6.12 phe NICAL tet ck eee 4.5 OOO. .9.2-9.5 ss sf (Pb;O,) . Sapte. 0.000-( TS.) - ceeansulpliater cnc eee 6.23 ee SUpnOCyana ten." 3.32 ae BUNLESLALE Sis o'er 8.235 [en Ae ees es ee me i .86-1.02 Lime (unslacked)........1.3-1.4 abet Eel te | een a oa 2i3=—219 Ligestone ta. hee eer a 1.86-2.84 Einoleume.. 225 EeD5“1:3 Linseed Oil (raw). . 93 —.034 is zs (boiled). . iniaaoic Litharge (natural)... . 2+ + 7.83-7.98 ¢ Lariilicia le eae 9.3-0.4 Lithium: Carbonatesn:.c02-221 iy Chloride: ....., . 1:908-2.074 Malachite: se succwe ae tate. 3.85 Manganese Chloride (MnCh4 HO) Biases. 1.913 Manganese Nitrate...... 1.82 a Oxid (MnO)..5.09—5.18 oe “* (Mn0O;) 5.026 (Mn2O3)4.325-4.82 Sulphate (7$ (a9 (MnSO.7H20). 2.092 Marble: APERIGart Mit cote aa ee 2.8 British “jc ate! a cee on pa 398 CHEMISTRY AND TECHNOLOGY OF PAINTS SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued Marble: Carrara stesa sere at ee 2.72 Egyptian, Green. . ....2.67 Florentine G25... -235 252 French 5.at ee aa ee 2.65 Mail sf ee eae E.6—2.5 Masonry: Ashlar Granite... 5s.62.37- LAUIESTORE) a wie. 227 “\) Milstone,’: ... 2306-2." “ . sandstone... .. «2.61 Rubble (dry) a2 =. 2.27 a (mortar) so5..4 2:42 Meerschaumia: .cu-3 sear .QQ-1.28 Mercuric Chloride. ....”. 5.32-5.46 e Oxid (hota aa II.O-I1.29 Mercuric Sulphide: (Hes black) 1 3.eob aoa 7.55—-7.70 (Hp ted) S. aiee. 8.06-8.12 Mercurous Chloride: (Calomet): 07a woes 6.482-7.18 Methyl Alcohol. ........ .7984 (15.°) Methyl Ethyl Ether..... .7252 (0. ) Mica re. RN aie eee 2.65-3.2 Milk. ows}. eee 1.028-1.035 Milk: Sueararha. secs ae 1.525 (20.°) Molybdic Acid: Ho oO Os 3.124 (15°) Morphine aye ts 79 5. maa 1.317-1.326 Mortar (hardened)..... .1.65 Mutton Suet (m.p.47.° C.) .92 Napthalena: ancy. wee 1.1517, : (reve Naphthol-a.. a: ate 1.224 (4.2 C} ms | SO Re I peer to, 8 B40) Neatsfoot-Oil. 2. So... .914 (39. F.) Niekel (ralled).20. 7. age. 8.67 I CARY Gk sclera e 8.28 Nicotine - iy. eae 1,011 4% Nitraniline:m...2o a0 ean 1.43 rs Saas Ae Ca 1.424 Oats: sii oi ee eras ata Ochiern st a ae ee 3.50 OleiGAcidy. 3 2. ee 8908, (ie. 20" Oolitic scones: et Se 1.89-2.6 Opalinn a isu ak Sone 2.20 Oralit Aid so asap 1.653 (18.°C.) Ozone 7 oie, tt eee eee 1.658 (A.) PalraiticlA cin wn uceinee ene 8465 (7 Gtos) Palm Oil (m. p; 30.°Ci).. > <005 PADSrES hen cee e eee O05 Paraffine: Mop 38ie $2 Cute ae Ore ed Mm. p..$2:-§65C. fon on o6= 08 Pearls).2)) 3. 2°72 Peat) 2. ches T.2-15 Petroleum Ether: b.. p: 40-90; 6 ee ae .65-.66 Phenol." 9% 125 oe eee E.0507133, 00) Phosphorus Shr ae 1.8232 4 (rea). . 21% Phthalic Aci < siacn eee 1.585—-1. 593 “ anhydride... 1.527. C.) Picric. Atidvica ase aes 1.813 Pinene 6) S:ilccues eeeecaraem 8587 (20.° C.) Pitch. 23 eee 1.07-1.10 Plaster of Paris: a. ane 2.96 Platinunis oe).ne eee py eny 3 Porcelain: Berlin ee Me ee eee 2.29 Meissen :<") 2). Aone 2.49 S@VLes:.’.! ays. ease 2.24 China 2,0: te eee 2.38 Portland Cement....:.. 53.25-1-58 Potash. 4.6. Gee 2.10 Potassium. 34 eae eee 875 (13 ) ze Bromide.«.....4.42: 780 ss Carbonate... . 2.29 &§ te Sacra 043 . Chlorate... -/2i344 (17. 3) sm Chloride...) AbteGa se iz Chromate. .. . 2. 721 Os 2 : Cyanide 2 1.52 (16° ts, 4 Dichromate. . . 2.692 (4°) 3 Ferricyanide. .1.8109 an ) - Ferrocyanide . 1.8533 (17°) u Hydroxid..... 2.044 * Todideyc. 7. 30aa3 (24.3°) it Nitrate: 2. ea Permanganate 2.70 ‘ Sulphate... .. . 2.6633 4 Shy Acidag oe # Sukphide K2S.. 2.13 Sulphocyanate 1.906 Tartrate.: 0078 Potatoes: <....."e eee eee 1.10 Pumice.’ nat.)i sn oc on aes “*: (AYtH joensen ee aaa Pyridini...2 ae eee 9855 (15. 7) Pyrogallol-2 2. eee 1.463 (40.-) Realgar Asim /5. 9). 3.4-3:0 Red Leads 23 eu aaa 9.07 Rosin? 2") eee Dee Ruby; i. sete 3.95—4.02 Salt. (table). ae eee 2.15-2.17 Sand (dry)}s5 7 c.aeeeeeeeee 1.4-1.65 ‘* moist). .5 eee 1.9—2.05 Sandstone :s:..)) kee eee 2.2-2.5 ANALYSIS OF PAINT MATERIALS 399 SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued SAUD ONES Oo re 3.95—4.02 DETOEMEMOt a oo! 5 es 2.4-2.7 BICOMMCIVSL a. o.s 2.49 (10.°) ‘“‘ (graphitic) . .2,.0-2.5 Me (amorphous) . aoe 2.00 ES A) a ee 1.56 silver Chioride.......... 5. Se Dee VANIGE. © ix 2. 3.9 SPN SELALE 6 sc5 Fs on 5 4. ee (19.°) PERS Seales Sis x har ia *. 2.05—2.7 eripy (loose. 26.01... E26 Sodium Picea tee sean. 1.4 Bicarbonate... .. 2,10-2,22 Pome OTOMICE s,s kk: 2.95-3.08 “< Carbonate famiiyd.,) 25. .2:43-2.51 ~~ Carbonate pet) oe 46 (17) Pe COMMIEMAG cy eisin wi 3 Pe Wis Gg ee eenrate tc... a71 {16.°) fo Dichrraate:..... 2.52 (16.°) pe BRAID OKI wuss: so. 21-3 Seren NIG At eters. st 2.267 #2 See Nite Pets ok 2k 7 PE XI ee, 225805 Ae Se kes nar 2.805 oe. Phosphate NaeHPO.12H,O 1.5235 (16.°) Potassium Tar- fete eS ay - Sulphate (anhyd. E 671 4 . 10H,O. .1.492 ce = iy Sulphide Nags... 2.471 ) sulpkite 7H.O: + .1- 561 s a eides. TA8 eee Pabirate. 3.5. 1.794 ** Tetraborate foilreso a: F094)" «< Thiosulphate iL) ie oe os, 1.729 (17.°) eee Pungstate... 6. .3.259 (47-5) Spatmculron Ore... 2... 3.7-3-9 Stannous Chloride 2H,O. .2.71 (15.5°) aT elign wey fee. ees: 1,5371.50 Stearic Acid. 2.2... 8428 % Seq rUriee eee os Gans .9245 (65. ) Sa WS, Seo ee 7.0-7.8 strontium i ohiorate.... ...3.152 Strontiam,Nitrate....., .2.24—2.98 SUPATACANG) oc Gel oe i, oy eB pe Sulphur FEO Bren as ety, ¥o>-amorph solts a7 aes (0.°) Pe aplastic. :. ; 1.09 < monoclinic SB... EE-O55 ee TEGIN ECA ee 2.05-2.07 (0°) Sulphur Dioxid rece, © 2.2039 Sulphuric Acid H,SQ,... . 1.8342 48 bie TLCS Oe coats mn lt a 2.6-2.8 Poles sepa eo eee 2.7 Me ALtavicsAcid 3% -4o ttc. 1.666—-1.764 Perpineolisaenas (ano ee. ck x 9357 (20.°) Thymol (3:2:1). . 0941 (0.°) Titanium Oxid TiO... Pn -3.75-4.25 OWenel: seo eh a, OL aC 866 29 TOWING, “A Ake eee .998-1.046 Tungsten Oxid WO,: (OrOWh seas ee oe: 12.11 Tungsten Oxid WO;: BvELLOW Ne et edge cor 7,16 RA ans oe ee E393 CuCl aes ts ee 8 dee ie 1.855-1.893 WN CEGHOUIS ie te tt Simi esa 1.9 Wax, Bees: Yellow m.p. 62.-62.5.°C .96-.965 White m. p..63.—63.5°C. .96-.969 Wax, Japan: (m. p. §3.5° 54-5"). + -992 WV Tie Peete eh oa .7-.8 Wood (see table on page 351). Wool (sheep) air-dry..... E32 AM LCNG On aay 2 kee ee 8932 (c.°) Sees PEN aris eek ae 866 2% RRS a ewe Seen. kr ee 8801 (0.°) Zinc PCCLATE. Oe eG GY Blende ZnS. . .4.03-4.07 ee Carbonate. sa. es shes 4.42-4.45 en CRIOUe reader ae sete ae OE OSI Socio he ee cet 5-78 ‘* oup hate anya, ase 3.6235 (15.°) ig 7H20..... 1.964 CA Reh a) uvin CoM Uncen et 3.98 (All temperatures, unless otherwise noted, are given in Centigrade degrees.) CHEMISTRY AND TECHNOLOGY OF PAINTS SPECIFIC GRAVITY OF THE ELEMENTS 400 Alumni ae ee ne Se Anton yin te ee et 6.62 Arcot: 8 astece 6 coe 1.379 (Air-I) ATSENIC. Whe peor ee cee 57.3 Baran ee te tee 2075 Bisnigtn ys: ea oe eee 9.80 Boron Aaa teen ee ae 2.50 Bromibes. > eee 3.15 (Air-I) Cadniium a) ee 8.64 Caesitlin. ca fate ners 1.88 Calcii 2. utero ote daP7 Garbon. eee eee Gee Ceriimeag aestuarii 6.68 Chiorne. a¥-7) see. 2.49 (Air-I) Chromitim.3 4 et 6.50 Cobaltswieci.s ot be ae 8.60 Columbium (Niobium). 7.20 Coppers chem uctehiere 8.933 Forbiuii ges ese ees ae: Wey Binerined, bee 1.26 (Air-I) Gadolinium. -.7-4)a cee mele 32 Gallina {745-50 aera 5-95 Germaniunis so.ae ee .469 Glucinum (Beryllium).. 1.93 Gold; acnee aS eee 19.32 Hlelitimn Seen poe eee .1363 (Air—-I) Hydrorven: 52 a. ae .0696 (Air—-I) Tridiain Seas tar eee es yee Jodine wees ee 4.943 eiditum . chee ce ee 22.42 Tronts Gye Se oats 7.86 Krypton 26-2 eee © 2.818 (Air-I) Lanthamtina 5: cia Os 46 Téa ds 2 See Wick tae wa) ray Tathtum 5c sees cee 2 59 Magnesiunisverce. aoe arter 4. Manganese. 5a) eee 7.39 IM CRCUIY cheese are E355 Molybdenum. +. ..%.., 8.60 Neodymium wes) en 6.956 Neon i408 os) see .674 (Air-I) Nickel ssgrg, Sinome see 8.90 Nitrogen. ae 96737 Osmium jc.2 2, pee 22.48 Oxygen.) eee 1.10535(Air-I) Palladium... ee. ee II.40 Phosphorus: (Whité)) 73 =aeeeee 1.83 (Red)? 35 see 2.20 Platinum 4a 21.50 Potasstuny. to. 0 eee 87 Praseodymium 6.4754 Radium 4 ee Rhodium:<,.a ae sea 12.10 Rubidium?<) ape Tis Rutheniums 7a eee 12.26 Samarium eee foyer ae Scandium. < yee cee Selenium. 272 ees 4.8 Silicon: (Cryst: 3 2 eee 2.39 (Graphitic). eae 2.00 (Amorph.) 2126 Silver. 2. eee eee 10.50 Sodiuni 3a eee .978 Strontigm 3.2 eee oie4 Sulphur 25 ose 2.07 ‘Tantalum <-> see 10.4 Tellurium: 4 eee 6.25 Tetrbium:<1 73) eee Thalltum: 5), eee 11.85 Thorium: 2 = q9seeeee LT,.00 Thubum,4.. eee Tit. 433420 eee 7:20 Titanium (72. ieee Tungsten: (Wolframium)...... 19.1 ' Uranium see 18.7 Vanadium. ee 50 Xenon. >... see 4.422 (Air—I) Ytterbium .,.2 ee Yttrium... poe 3.80 Zinc: .... 25 29. 7.25 ZifCOniUn <4 6: eee 4.15 PouNbDS OF OIL CONTAINED IN 100 POUNDS OF AVERAGE PASTES MADE FROM THE VARIOUS DRy PIGMENTS! Ashestine 06 iGicnsaa. ie one eee 32 Barytes4 Natjto auto care 9 Black BONG. - a eee aaa 50 Black’ Dropsacgcteus eee 50 Black, Hydro Gas Carbon....... 88 Black, Lampws ok new eee ee 78 Blapcukixexsc atecoser beens 25 Blue, Chinese or Prussian........ 62 Blue, Ultramannes eee eee 28 Brown, Mineral.) 0) see 24 Brown, Vandyke. 3.0 ee eee 58 China Clay.5: 53h 28 Dutch Pink (Quercitron Lake).... 28 Graphite (Plumbago), 90%...... 48 Green, Pure, Light, Chrome: .7. 7; 21 Green, Pure, Dark; Catomenaae 28 ANALYSIS OF PAINT MATERIALS 401 Green, 25% Color, Light Chrome. 18 Sienna, Raw Italian............. 52 meee or Watk Chrome:--20- Silex. oe ec le eee 24 Green Earth (Terra Verte)....... G25) sumbers DurntcAmerican 21 ox. 36 Green; fimerican, Paris... ........ Sa Mer, Rave PA INCTICAIA. fu. 5): 38 Meee eieiish Paris... es. 5: Zong umber, burnt Purkeye tis... sue. 47 fieen, Ultramarine... 2... ss Bienes Leber RA We EUPKEV ic 2 ys.o). lat. 48 Re es Sb gs bes wiles 22 Vermilion, American (Chrome Rec) 18 rinepnineis. 25. 85-50 oe go-25), » Vermilion; English (Mercury)...,. 14 PIOMPOAATICTICAT) or. bw. oes 28 ~ White Lead (Basic Carbonate)..... 10 PPGMGem EFCC): Ss wk ae es 28 White Lead (Basic Sulphate)..... 11 Pearestazolden (Pure). 0. ..4... gore White, Panic (Whiting 22.0. 20 Remerindian. (Pure o$:.%) <.. i..% -4 25-7 VelowsLemon, Chrome, wos... 128 LeU OMU CSE 14 RS ae COverey cllow. Med). Ghrome.!. 2) 05 3s 30 Poe ee CICUAN e545 oe ee ee 23 Yellow, Orange, Chrome......... 20 meaeweon, Oxia \Pures 5.5.25... a5 Yellow, Dk. Orange; Chrome... . 18 USSU ASS ae Ag POigeenyATCOLICHE a. pein tu ok eee Sg tk 12 Digna, RaW AMIetICAnN .....°.... 45 Zinc Oxid (American), ordinary .. 18 Siehna, Burnt [talian....4.. 5... Agee Linc. Oxid (White seals 25.0.0. bao 1 These figures are approximately correct. For instance, lamp black is given as 78 pounds. There are, however, some lampblacks which require as much as 100 pounds, and others which require as low as 70 pounds, but 78 pounds is the exact amount for commercially pure lampblack. This figure means that roo pounds of lampblack will require 78 pounds (about to gallons) of oil to make a stiff paste. SpectrIC GRAVITY OF VARIOUS Woops Air dry Fresh LNG Ts Peete © ee ewer eee a50e 85 B75—100 PACT Ma ner he Sas Ae 425-68 S62=- 17, O1 0) 6) Ree Se ere SCO 04 Se La ASE RU aor on i a ge Ne a .57- .94 -7O-1:.. 04 RE rechiey Sok ka oe ES te eh .80-1 .09 [S05 EO ie tee ee ee .QI-1.16 | 1.20-1.26 (etn Bn aeee a lye has, By ao eg Al Ce are Cherry hose eka .70— .84 | 1.05-1.18 ULC eee ke Teed one nee ee Hod ELV ck oaarce ek ant AS atopy 7O-1.18 Ae ape Ae Rin ig ee Marine Bera Su awn ia Nee Pa howan yo eek ae he B= TE OO ian tanh ee ati iA DIES Bek eee ciara pare, OF ROS-1505 Mountain Ash. tee 69— .89 Seared 2 [Da ora Re ees tens Snr hE 69-1 .03 93-1. 28 Peni o® vets ear OF 75 Q6-I.07 PANES rc: at ee oe ee 35— .60 40-1 .07 Plameaxae eto toek oe .68-— .90 oy et ee Wy, PODIAL A eee chica o- 530-50 jOf=1 7107 fF WILLOW asda tc eine te ot 49- .59 fie eae 402 CHEMISTRY AND TECHNOLOGY OF PAINTS TABLE SHOWING THE COMPARISON OF THE READINGS OF THERMOMETERS Celsius, or Centigrade (C). Réaumur (R). Fahrenheit (F). e er asa F C R F — 30 — 24.0 — 22.0 ae: 18.4 73.4 — 25 — 20.0 — 13.0 24 19.2 7522 — 20 — 16.0 — 4.0 25 20.0 TFL — 15 — 12.0 + 5.0 26 20.8 78.8 — 10 — 8.0 Be © re: 27 21.6 80.6 — 5 — 4.0 23.0 28 22.04 82.4 — 4 — 3.2 24.8 20 23.52 84.2 — 3 — 2.4 20.6 30 24.0 86.0 — 2 — 1.6 28.4 31 24.8 87.8 -— I — 0.8 40°22 32 25.6 89.6 33 26.4 QI.4 Freezing point of water. 34 S22 93.2 35 28.0 95.0 fo) 0.0 32.0 36 28.8 96.8 I 0.8 33.8 ay 29.6 98.6 2 1.6 35.6 38 30.4 100.4 3 Phe’ carer 39 hae’. 102.2 4 ano 20g 40 32.0 104.0 G 4.0 ALLS 4I 328 105.8 6 t 4.8 42.8 42 33.6 107.6 7 5.6 44.6 43 34.4 109.4 8 6.4 46.4 44 2059 iit 9 yea) 48.2 45 36.0 E53 0 10 8.0 50.0 50 40.0 T2220 II 8.8 5r.8 55 44.0 131.0 12 9.6 53.0 60 48.0 140.0 13 10.4 re! 65 52.0 149.0 14 to 2 Bias 70 56.0 158.0 15 12.0 59.0 75 60.0 167.0 16 12.8 60.8 80 64.0 176.0 17 13,0 62.6 85 68.0 185.0 18 14.4 64.4 go 72.0 194.0 19 reg 66.2 05 76.0 203.0 20 16.0 68.0 100 80.0 2120 21 16.8 69.8 22 17.6 wi 0 Boiling point of water. Readings on one scale can be changed into another by the following formule, in which /° indicates degrees of temperature: Réau. to Fahr. Cent. to Fahr. Fahr. to Cent. ZR 4n3e eB SC unsa mae 5( er-3°)-Pc 4 5 9 Réau. to Cent. Cent. to Réau. Fahr. to Réau. Se See Bagge Ce ‘(Pe P-32)-PR 4 5 9 BIBLIOGRAPHY Publications of great value to the paint manufacturer may be obtained from the various government departments. Address the Superintendent of Documents, Government Printing Office, Washington, D. C., for a list of titles of publications of interest to the paint color and varnish industry. The cost of most of these publications is five cents. Specifications, reports, etc., are also published by the Navy Department, Department of Agriculture, etc. PERIODICALS American Paint Journal, St. Louis. American Society for Testing Materials — Transactions. Chemical Abstracts. Chemische Zeitung, Ber.in. Chemical and Metallurgical Engineer, N. Y. Chemical Age, London. Chimie et Industrie, Paris. Drugs, Oils and Paints, Philadelphia. Farben Zeitung, Berlin. Journal of the American Chemical Society. Journal of the Franklin Institute, Philadelphia. Journal of the Chemical Society, London. Journal of the Society of Chemical Industry, London. Journal of Industrial and Engineering Chemistry. Journal of the Ou and Color Chemists Association, London. New Jersey Zinc Co., Bulletins, N. Y. Oil, Paint and Drug Reporter, New York. Oil and Colour Trades Journal, London. Paint Manufacturers Association, Bulletins, Washington. Paint, Ou and Chemical Review, Chicago. Paint and Varnish Society Papers, London, Paint and Varnish Record, New York. Revue de Chimie Industrielle, Paris. 4093 404 BIBLIOGRAPHY PAINT VARNISH AND COLORS ABRAHAM, H. Asphalts and Allied Substances. ANDES, Louris E. Iron Corrosion and Anti-fouling Paints. London, Scott, Greenwood & Son. Bearn, J. G. The Chemistry of Paints, Pigments and Varnishes. New York, D. Van Nostrand Co., 1924. BottLer, Max. Die Lack- und Firnisfabrication. Halle, Wilhelm Knapp, 1908. Cuurcu, A. H. The Chemistry of Paints and Paintings. London, Seeley Co., Ltd. DoERNER, Max. Mahlmaterial. Munich, 1922. Ertner, A. Uber Fette Ole. Munich, 1922. FRIEND, J. Newton. An Introduction to the Chemistry of Paints. London, Scott, Greenwood & Son, tgto. FRIEND, J. Newron. The Chemistry of Linseed Oil. London, Gurney & Jackson, 1917. Faurion, W. Die Chemie der Trockenden Ole, 1911. GARDNER, H. A. Physical and Chemical Testing of Paints, Varnishes and Cotors. Washington, 1925. GARDNER, H. A. Paint Researches and their Practical A pplication. Washington, Judd & Detweiler, 1917. GARDNER, H. A. Paint Technology and Tests. New York, McGraw- Hill =161 HotiEy, C. D. Analysis of Paint and Varnish TIO: New York, J; Wiley, oro: Ho titey, C. D. Analysis of Paint Vehicles, Japans and Varnishes. New York, J. Wiley, 1920. Heaton, Nort & Hurst, C. H. Painters’ Colours, Owls and Varnishes. London, Charles Griffin & Co., 1922. Hurst, G. H. Dictionary of Raw Materials, Used in the Manufacture of Paints. London, Scott, Greenwood & Son, 1917. LewkowlrtscH, J. Oils, Fats and Waxes. New York, Macmillan Co. Moret, Ropert S. Varnishes and their Components. London, Oxford Technical Publications, 1923. PICKARD, GLENN H. Contributions to the American Paint Journal on paint and varnish materials; also to the Paint Man’s Pocket Library. St. Louis, American Paint Journal Co., 1922, ’23, ’24, 25. SaBiIn, A. H. The Industrial and Artistic Technology of Paint and Varnish. New York, J. Wiley, 1917. BIBLIOGRAPHY 40s SABIN, A. H. German and American Varnish M anufacture. New York, John Wiley & Sons. Scott, W. W. Standard Methods of Chemical Analysis, 1917. SEELIGMANN & ZickE. Handbuch der Lack-und Firnisindustrie. Berlin, 1923. SMITH, JAMES C. The Manufacture of Paint. London, Scott, Green- wood & Son, 1924. Tocu, M. How to Paint Permanent Pictures. Materials for Painting Permanent Pictures. TRUELOVE, Rupert H. Oils, Pigments, Paints, V arnishes, etc. London, Sir I. Pitman & Sons, Ltd., 1022. VAN Patten, Natuan. Bibliography of the Corrosion of Metals. Marblehead, 1923. PIGMENT COLORS Berscu, Joser. The M anufacture of Earth Colours. London, Scott, Greenwood & Son, 1921. BerscuH, Joser. The Manufacture of Mineral and Lake Colours. London, Scott, Greenwood & Son, root. GENTELE, J. Lehrbuch der Farbenfabrikation. Benue F. Vieweg & Sohn, 1909. JeNNIsON, Francis H. The Manufacture of Lake Pigments from Artificial Sources. London, Scott, Greenwood & Son, 1924. Lincke & Apam. Die Malerfarben. Esslingen, 1913. Metrrzinskt, S. Handbuch der Farben, Fabrikation, Praxis und Theorie. Vienna, A. Hartleben, 1808. Parry, J. and Coste, J. H. The Chemistry of Pigments. London, _ Scott, Greenwood & Son, 1902. Rrerautt, J. R. Colors for Painting (obsolete, but of Perey Binledelphia. hehe Rose, F. Die Mineralfarben. Leipzig, O. S. Spamer, 1916. Tocu, MaximiiAn. Materials for Permanent Painting (artistic). New York, D. Van Nostrand & Co., tort. ZERR & RUBENCAMP. A Treatise on Colour Manufacture. ZERR, GEORGE. Tests for Coal Tar Colours in Aniline Lakes. DYES, FORSLAKES Society of Dyers and Colourists, Colour Index. 1924. Manchester England. b INDEX i Balata, 285 Barité Er Acetylene black, 106 Barium carbonate, 121 Acid resin in paints, 153 analysis of, 359 Adulteration with inert pigments, 108 chloride, 120 Albalith, 40 peroxide, 120 Alizarin, 143 sulphate, 110 Alkali-proof green, 91-93 sulphide, 41, 119 Aluminum hydrate, 140 Barnacles, 149 Aluminum silicate, 127 Barytes, 110 American tung oil, 218 analysis of, 359 American turpentine, 251 Base, lake, 114 American yellow ochre, 67 Basic lead sulphate. 32 Ammonium oleate, 291 analysis of, 332 Ammonium stearate, 291 . Battleship gray, 118 Ammonium tannate, 291 Bottom salts, 31 Anatase, 48 Becton white, 4o Angular blanc fixe, 121 Benzene, 273 Anti-corrosive paint, 301 Benzine, 268 Anti-fouling paints, 150 Benzol, 273 Anti-rust — see corrosion Benzol black, 106 Antimony oxid, 50 Bibliography, 403 Antimony sulphide, 73 Bismuth, 114 Antimony yellow, 73 Bitumen, 294 Antwerp blue, 87 Black fungus, 324 Arsenic sulphide, 74 Black lead, 99 Arsenic yellow, 74 Black toner, 105 Artificial calcium carbonate, 135 Black pigments, 95 Artificial vermilion, 144 analysis of, 354 Artists’ colors, 287 acetylene, 106 Asbestine, 128 benzol, 106 analysis of, 357 carbon, 98 Asbestos, 128 charcoal, 102 Aspergillus flavus, 324 coal, 104 Aspergillus niger, 324 drop, 104 Asphaltum paints, 155, 204 graphite, 99 Atcheson graphite, too ivory, 104 lamp, 96 mineral, 107 B sugar house, 95 Baking japans — sec enamels vine, 103 fish oil for, 230 Blanc fixe, 114 407 408 Blanc fixe, analysis of, 355 angular, 121 Bleaching of linseed oil, 175 China wood oil, 199 Blown linseed oil, 187 soya bean oil, 232 Blue lead, 60 Blue pigments, 82 Antwerp, 87 bronze, 87 Chinese, 87 cobalt, 85 Guimet’s, 83 milori, 87 Paris, 87 Prussian, 87 analysis of, 351 steel, 88 ultramarine, 82 analysis of, 352 Bottoms, lead, 31 Bronze blue, 87 Brookite, 48 Brown pigments, 75 Brown, Vandyke, 80 Burnt ochre, 78 Burnt sienna, 75 Burnt umber, 77 C Cadmium lithopone, 73 Cadmium orange, 73 Cadmium yellow, 73 Calcium carbonate, 130 INDEX production in America, 218 refining of crude, 199 . Chinese blue, 87 Chinese wood oil — see China wood oil Chirt, 114 Chromate of zinc, 71 Chrome green, 90 Chrome oxide green, or Chrome orange, 70 analysis of, 348 Chrome yellow, 70 analysis of, 348 Clay, 126 analysis of, 357 Coal, 104 Cobalt blue, 85 driers, 277 linoleate, 281 oleo resinate, 281 resinate, 280 salts, Inorganic, 277 soap drier, 281 Cod liver oil, 236 Cod oil, 243 Colophony, 250 Combining mediums, 285 Commercial whiting, 130 Concrete as anti-corrosive, 313 corrosion of steel in, 315 paints for, 152 Copper anti-fouling paints, 151 Copperas, 65 Copper carbonate, 93 Corn oil, 247 Calcium sulphate, 63 Corrosion of steel in concrete, 315 analysis of, 356 Corrosion of structural steel, electro- Carbon black; 98 lytic, 311 Cement as anti-corrosive, 313 Corrosion, protection against, 301 Cement, paints containing, 155 Cream ochre, 68 Cement, paints for, 152 Chalk, 130 Chalking of white lead, 29 Charcoal, 102 Charlton white, 40 China wood oil, 191 deodorization, 222 examination of, 203 heat and quality tests, 211 Creosote in shingle stains, 161 Cresol, 161 D Damar in enamels, 156, 188 Damp-resisting paints, 155 Darkening of pigments, 297 Deodorization of tung oil, 222 Diatoms, 126 Diazotization, 141 Dispersion, 391 Drop black, 104 Drying of linseed oil, 168 Durability of paints, 146 Durex white, 121 Dutch Boy red lead, 55 Dutch process white lead, 26 E Emerald oxid green, 93 FEmulsifier, pine oil as, 290 Emulsifiers, 287 Enamel oil, 184, 186, 187 Enamels, 156 Erythrosine, 289 Examination of China wood oil, 203 Examination of pigments, 326 Exfoliating paints, 150 Extenders, 108 Extra gilder’s whiting, 130 F Fading of pigments, 297 Ferric oxids, 62 analysis of, 344 Ferrite, 72 Ferrox, 72 Fibre, asbestos, 127 Fillers in white lead, 30 Fine grinding, 292 Fish oil, 236 treatment of, 238 Flat paints, 121, 160 Floor paints, 161 Florence zinc, 23, 38 Franklinite, 36 French ochre, 67 French turpentine, 251 French zinc, 38 Fuller’s earth, 126, 127 Fungicides, 325 Fungi on paint, 322 G Galena, 22-60 Golden antimony, 73 INDEX Golden ochre, 68 Graphite, 99 analysis of, 355 Gray, battleship, 118 Gray ochre, 68 Green fungus, 324 Green ochre, 69 Green pigments, go alkali-proof, 91-93 chrome, 90 chrome oxid, ot copper, 93 hydrated chrome oxid, 93 Veronese, 93 Crrcen cal. 23,038 Grinding, 8, 290 Growth of fungi on paint, 322 Gum chicle, 285 Gutta percha, 155, 285 Gypsum, 135 ie! Herring oil, 243 Hydrogen sulphide, action on lead, 30 action on zinc, 36 : Hygiene, painter’s, 319 Hypernic lake, 144 Tlmenite, 48 Imitation vermilion, 144 Indian red, 64 Inert fillers, 108 Inert fillers in white lead, 30 Infusorial earth, 122, 126 Tron oxids, red, 62 analysis of, 344 Iron oxids, yellow, 72 Ivory black, 104 it Japanners’ brown, 169, 186 Japanners’ brown oil, 186 Jersey Lily White, 40 409 4IO K Kaolin, 127 Kieselguhr, 126 King’s yellow, 74 ib; Lake base, 114 Lakes, 140 Lampblack, 96 Lapis lazuli, 82 Lead, black, 99 Lead carbonate, 27 oxids, 52 poisoning, 27, 319 sulphate, 31 white, 25 Leaded zinc, 24 Leather, fish oil for, 239 Light-proof lithopone, 44 Limeproof colors, 144 Linseed oil, 164 bleaching of, 175 boiled, 187 drying of, 168 porosity of, 172 specifications for, 180 Liquid mills, 8 Litharge, 52 Tithol red, 143 Lithopone, 40 analysis of, 338 light-proof, 44, 47» zinc oxid in, 47 Lumbang oil, 223 M Madder lake, 143 Magnesium silicate, 128 Maize oil, 247 Marble dust, 134 Maroon lakes, 145 Mass tone of colors — see shade Measure, tables of, 394 Menhaden oil, 237 Mercury in anti-fouling paints, 151 INDEX Mercury, vermilion, 141 analysis of, 347 Metric — English conversion tables, 394 _ Mills, 6 liquid, 8 paint, 8 pebble, 19 roller, 22 Milori blue, 87 Mineral black, 107 Mineral Point zinc, 23, 88 Mixed paints, 1, 6, 146 analysis of, 362, 360 Mixers, 6 N Navy, U.S. — use‘of blanc fixe, 11 New Jersey zinc, 23, 38 O Ochre, 67 Oil soluble colors, 145 Oils, analysis of, 379 American tung, 218 boiled linseed, 187 China wood, tor cod liver, 236, 243 com, 247 enamel, 184, 186, 187 fish, 236 herring, 243 japanners’ brown, 186 linseed, 164 linseed, boiled, 187 maize, 247 menhaden, 237 perilla, 188 pine, 258 _ porpoise, 236, 243 sardine, 242 seal, 2209243 soya bean, 225 stand, 184, 187 stillingia, 224 tung, 191 whale, 236, 243 winter pressed, 244 INDEX Oleum white, 40 Orange, chrome, 70 analysis of, 348 Orange mineral, 53 analysis of, 343 Orpiment, 74 Orr’s white, 40 Oxids of lead, 52 Ozark white, 34 i Paint, analysis of mixed, 362, 369 anti-corrosive — see corrosion anti-fouling, 150 containing Portland cement, 155 damp-resisting, 155 determination of water_in, 377 enamel, 156 flat wall, 160 floor, 161 ‘for cement and concrete, 152 mills, 8 mixed, 1, 6, 146 mixed, analysis of, 362, 369 poisoning by, 319 shingle, 161 to prevent corrosion, 301 waterproof, 155 Painter’s hygiene, 319 Paper coating, 114 Paranitraniline, 141 Para red, 141 Para rubber, 285 Para toner, 141 Paris blue, 87 Paris white, 130 Paste figures for pigments, 400 Pebble mills, 19 Pencillium Arustaceum, 324 Perilla oil, 188 Permanent white, 114 Peroxide of barium, 120 Pigments, amounts of, required for paste, 409 fading and darkening of, 297 standards, 326 testing and examination, 326 AII Pine oil, 258 Poisoning lead, 27, 319 Poisonous anti-fouling paints, 151 Poisonous paints for fungi, 322 Ponolith, 40 Porosity of linseed oil films, 172 Porpoise oil, 236, 243 Portland cement — see cement Prince’s metallic brown, 79 Production of tung oil in America, 218 Protection against corrosion, 301 Prussian blue, 87 analysis of, 351 Eutty, £32 Quartz, 123 Raw sienna, 70 Raw umber, 77 Realgar, 74 Red, Indian, 64 Red lakes, 144 Red lead, 53 Red oxides, 62 analysis of, 344 Red Seal zinc, 23-38 Red, Venetian, 63 Refining of China wood oil, 199 Refractive index, 389 Refractometer, Abbé, 3389 Refractometry, 389 Reinforcing pigments, 108 Reinforcing reds, corrosion of, 315 Resinate of cobalt, 280 Rhizopus Nigricans, 324 Roller mills, 22 Rosin, 250 determination of, 371 Rosin oil, detection of, 375 Rouge, 66 Rub-outs, 327 Rusting — see corrosion Rutile, 48 S Salt water, influence on paint, 117, 119 Sardine oil, 242 Scarlet lake, 144 A412 Sea coast painting, 32, 240 Seal oil, 236, 243 Sea water, influence on paint, 117-119 Shade of pigments, 327 Shingle paint, 161 ~ Shingle stain, 161 Ship’s bottom paints, 150 Sienna, raw, 70 analysis of, 345 Suex, ores Silicas-1 22 analysis of, 357 Silicate of alumina, 127 Silicate of magnesia, 128 Smokestack paints, 239 Sodium sulphate, 120 Sodium sulphide, 120 Soluble in oil, colors, 145 Solvent naphtha, 276 Soya bean oil, 225 blowing and drying of, 232 physical constants of, 231 Spanish white, 135 Specifications for linseed oil, 180 Specific gravity of elements, 400 Specific gravity of misc. materials, 396 Specific gravity of various woods, 4o1 Spirit, white, 272 Stains, shingle, 161 Stand oil, 184, 187 Steel blue, 88 Steel, corresion of, 301 electrolytic corrosion of, 311 Stillingia oil, 224 Stove polish, 99 Structural steel, electrolytic corrosion of, 311 Sublimed white lead, 31 Substitute turpentine, 273 Sugar house black, 95 Sulphate of barium, 120 Sulphate of calcium, 63 Sulphate of lead, 31 Sulphate of zinc, 39-40 Sulphide of barium, 41, 120 Sulphide of sodium, 120 Sunlight — influence on paints, 294 on pigments, 297 INDEX A Tables: atomic weights, inside front cover dry pigments in oil, amount required for paste, 400 metric-English conversion, 394-395 specific gravity of elements, 400 specific gravity of misc. materials, 396 specific gravity of various woods, 4o1 thermometer conversion, 402 weights and measures, 394-395 Testing of pigmemts, 326 __ Thermometer conversion formulas, 402 Timonox, 50 Titanium white, 48 analysis of, 340 Titanox, 48 Tockolith, 155 Toluidine toners, 142 Toluol, 275 Toners, 140 Tooth, 114, 124 Tungates, 234 Tung oil — sce China wood oil Turpentine, 250 American, 251 French, 251 Russian, 251 substitute, 273 wood, 251, 255 Tuscan red, 144 U Ultramarine, 82 analysis of, 352 Umber, 77 analysis of, 345 V Vandyke brown, 80 Venetian red, 63 Vermilion, artificial, 144 Vermilion, mercury, 141 analysis of, 347 Veronese green, 93 Verte antique, 93 Vine black, 103 Viridian, 93 INDEX W Watch-case rouge, 66 Water in paints, 286 detection of, 289, 377 Waterproof paints, 155 Weights, tables of, 394 Whale oil, 236, 243 White lead, 25 analysis of, 330 bottoms, 31 chalking, 29 crystals in, 29 oil absorbtion, 28 sublimed, 24, 32 White mineral primer, 134 White mixed paints, analysis of, 362 White, Paris, 130 White pigments, comparative merits of, 24 mixtures of, 24 White, Spanish, 130 White spirit, 272 Whiting, 130 Wood turpentine, 251-255 Xylol,-276 yi Yellow, chrome, 70 analysis of, 347 Yellow iron oxide, 72 Yellow ochre, 69 Zinc chromate, 71 Zinc, leaded, 24 analysis of, 333 Zinc oxid, 36 analysis of, 335 Florence. 23, 45 Green Seal, 23, 38 in lithopone, 47 Mineral Point, 23, 38 Red Seal, 23, 38 Zinc sulphate, 39, 40 Zinc, yellow, 71 Zincite, 36 Zinox, 40 413 D. 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