DEVELOPMENT OF A COLORED BELLEEK BODY HAROLD THORNTON GOSS THESIS FOR THE DEGREE OF BACHELOR OF SCIENCE IN CERAMIC ENGINEERING COLLEGE OF ENGINEERING UNIVERSITY OF ILLINOIS 1922 !Z 5, }^ 2 ^ Caa < H ns CL UNIVERSITY OF ILLINOIS Tune... .3. THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Harold Thornton Coss "THT BRVRLOPMRNT OP A COLORBO BRLLRRK BODY" ENTITLED IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF £.a.aMl.or ...Qf .. Sc? i.ence Digitized by the Internet Archive in 2015 https://archive.org/details/developmentofcolOOcoss TABLE OF CONTENTS Page I . INTRODUCTION 1 II. GENERAL FIELD TO BE COVERED 2 III. EXPERIMENTAL PROCEEDURE FOR BODE 7 Materials Used 7 Development of the Fritt 8 Development of the Body 11 Burning 15 Properties of the Burned Ware 16 Selection of the Best Body 18 IV. EXPERIMENTAL PROCEEDURE FOR COLOR 19 Casting Properties 21 Burning 22 Properties of the Burned Ware 22 Deformations 24 V. SUMMARY OF RESULTS 24 VI. GENERAL CONCLUSIONS 24 VII. ACKNOWLEDGEMENT 25 . . . . . THE DEVELOPMENT OP A COLORED BELLEEK BODY". I. INTRODUCTION. A belleek body i3 one of the mysteries of modern Ceramics. Although the general properties of the burned body are known, and the beauty and value of the delicate creamy ware made from it are fully appreciated , there i3 no authoritative data nor literature available on the subject. We know it was first developed by Mr. Armstrong and Mr^McBirney in 1863 in the little town of Belleek, County Parmanagh, Ire land, and that a factory was started there. Prom this factory came the first belleek ware.(l) A Mr. Bromley was engaged from Stoke-on-Trent , and he succeeded in putting the pottery on a commercial basis. In 1883 Mr. Bromley came to America and eventually assisted Mr. J.H. Brewer in hi3 development of bell- eek at Trenton ,N. J. Prom the old Ott and Brewer pottery has grown the Lennox , Incorporated .which is the only firm in the world at present making belleek which rivals the original. Mr.McBirney die d in 1884 and his partner shortly after. (2) The quality of the ware quickly degenerated , and although the original factory is still in existence , and makes parian v/are.the product i3 not to be compared with the early belleek. The secrets of the methods and materials are confined to the Lennox , Incorporated , alone. The original secrets died with the belleek founders. Prom occasional discussions in the Transactions of the American Ceramic Society by Professor Binns and Professor Purdy, we have our only technical literature on the subject. (1' '*Ce r amic Art in Great Britain" .L. -Jewitt. Pp. 601-609: (j?)" 19 th Century English Ceramic Art" .Blacker .Pp. 476-481. 2 From these discussions /are find that belleek, first of all, must have a high degree of translucency j that it must permit of cast- ing and jigger ing into thin wares* that it must have lo- drying and burning shrinkage , and that the burned body must be "free from color". (3) Further than this, the belleek must be ground very fine in a ball mill, a point highly essential to the work- ing of the clay and the clarity o r the body; the body must be low in flint and high in feldspar, md it must be vitrified either in bisque or gloss. It is glazed with a fritted lead boracic acid glaze at Cones 1 to 3, which is four or more cones lower than the biscuit firing. The glaze and biscuit should be cooled quickly, for when cooled slowly there is a tendency for the body to blister and turn blue, and for the glaze to pinhole. (4) The above information has been included simply to show how scanty the knowledge 0 * belleek is. From this, it is very evident that prior to developing a color in belleek, it is of prime importance to develop a satisfactory belleek. To this end, a field was laid out and fully investigated. II. THE GENERAL FIELD TO BE COVERED. By a very roundabout way, a formula came into the writers hands, this formula purporting to be the accurate formula of belleek. Its authoritativeness i3 quest ionable , but Professor Binns corroborated the field it represents as being representative o p true belleek. Accordingly , with this formula as a base, a field was laid out, both for fritt and for body. (3) Transactions American Ceramic Society. Vcl . 13 , p. 86 . (4) Transactions American Ceramic Society. Vol.2 ,p.l85. . • - . M | , . 3 The formula: Br itt Batch Thite glass sand 55 It). Feldspar 34 lh. Potassium carbonate 1C lb. Britt 20 lh. Calcined feldspar 64 lh. China clay 60 lh. Golding No.l 40 National 20 The ceramic formula for this hody is Britt K g O 2 .64 Al 2°3 Si 0 2 21.3 Body X p 0 .4 09 Al^O 3 Si 0 p 3.935 The field laid out and investigated is indicated on the two triaxial diagrams following. Po+assi u m Carbonate Feldspar 4 Cj ft' *o «/> <-0 ft Sc Field of Ffitt 5 6 Batch weights of fritt, from Triaxial Diagram Fritt body no. Sand Potassium carbonate Feldspar A 60 15 25 B So 10 30 C 60 5 35 D 50 15 35 50 10 5 F 50 5 45 G 40 15 - 45 H 40 10 5 0 I 40 5 55 Batch weights of body, from Triaxial Diagram Body no. Feldspar Fritt H. and G.A1 N.Ca. Fla. 1 40 25 23 6 6 2 30 25 30 7 .5 7 .5 3 30 15 23 6 6 4 40 15 30 7 .5 ? .5 5 30 15 36 9 . 16 9 . 16 6 60 5 23 6 6 7 5 0 5 30 7 .5 7 .5 a 40 5 36.6 9.16 9 . 16 9 30 5 43.4 10.8 1C .8 When the "body with the best pr operties and the appearance most typical of belleek wa s determined, a large batch of it was made up, and to this coloring stain s were added. Two colo rs were desired , pale pink and pale green . 7 III. FXPFRTMFNTAL PROCFFBURF FOR THF BOW. Materials Used Feldspar was the most important ingredient. Abingdon feldspar was used because it was the onhr kind available. In order to make it easier to grind.it was calcined in:,open saggers at Cone two. Before calcining.it was a creamy yellow color, and after calcining a very light pink. The silica was introduced as white glass sand from Ottowa Illinois. This was very finely ground, and in a purer state than flint. According to Professor Binns it is easier to mix than flint when used on a commercial scale. The potassium carbonate used wa3 of U.S.P. quality. It is readily obtainable in a pure state, and is cheaper than equivalent amounts of other potassium salts. Hammil and Gillespie A 1 clay was U3ed instead of Golding No . 1 .because the latter is not qn the market, and the former clay gives a good white color, with a clear translucency . A combination of equal parts of Florida and North Carolina kaolins also gives a good white color, and the plasticity is much better than when either is used alone. The combination was sub- stituted for the National clay, now unavailable. ( 5 ) (5) Transactions American Ceramic Society. Vol. 18, p. 621. 8 Development of the Bkitt. Before experimenting , it was not known what effect var- iations in the fritt composition would have on the hody. Aside from this, the ease of grinding, and the solubility were other points to be considered. The ease of grinding obviously affects the properties of the body with regard to its commercial prep- aration. The solubility affects the properties of the casting slip. Determination of the Sintering Temperature. The fritt extremes A,C,G,and I were investigated for the temperature desir- able for fritting. (it should be noted that no distinction is made between the terms fritting and sintering in the discussion. In the term fritt is included the fritted or sintered mixture of materials whose batch weights are given in the table on page 6. ) Accordingly, the potassium carbonate was dissolved in hot water, one gram of potassium carbonate to two and one half cubic cent- imeters of distilled water. The sand and feldspar were thoroughly mixed by sieving and then rolling intimately on oil-cloth , after which the salt solution was added, and the mixture stirred. After drying, the mixture was introduce:' into fire .clay' fritt crucibles which had been prepared in the following manner. The inside of the crucible was dampened and a powdered calcined flint coating was applied. Then, a cone shaped piece of paper was inserted, and the fritt batch dumped into the cone, after which the paper was withdrawn. This effectively prevented sticking of the fritt to the crucible or flint, and hence the crucible could be used re- peatedly, a3 the fritt shrank from the flint lining, and could be easily removed by inverting the crucible. 9 The fritts were fired in a fritt furnace which was huilt up of compartments , each similar to a gas pot furnace. The fuel was gas and air. By careful attent ion , the atmosphere was kept oxidiz- ing. Although at first trouble was experienced in fusing the out- side of the fritt and only barely sintering the center core, by slower heating up , conditions were adjusted to secure uniformity. At Cone 010, none of the fritts wase sintered. They appear- ed 3 imply dried out. At Cone 05 .sintering had barely started, but the mass was always of a dirty gray color , indicating incomplete combustion of the carbon, or incomplete oxidation. At Cone 03, sintering had well begun. At Cone 00, G and I were half sintered and hal" fused. At Cone 1,A and C were half sintered and half fused. At Cone 5 , all were fused. At Cone 10, a milky white .homogeneous fritt was obtained. This was very hard to break up, and hard to grind. Cone 1 was the best temperature for treating mixtures G and I as this gave sinters which ground easily, yet were clean and white. Cone 3 was best for mixtures A and C for the same reason. These cones represented about the only conditions at which sat- isfactory results could be obtained. Accordingly , the fritts were fritted as follows :- Mixtures A,B,C Cone 1 D,E,F Cone 01 G,K,I Cone 02 In no case were they cooled by immersion in water, as this would ■■ . 10 have washed out any soluble portions. Determination of the Solubilities. (6) For determining the solubilities , the specimens were ground , thoroughly mixed, and sieved between five and ten mesh. That which remained in the ten mesh was of such a size that the surface exposed was practically f constant. The quantity used was five grams. This was put in a mason jar with three hundred and fifty cubic centimeters of dis- tilled water. The jars were placed in a shaking machine making twenty one R.P.M. They were agito.ted for twenty four hours, No all owan c e was made for the influence of room temperature. After a few hours, the water showed a very slight turbidity , evidently due to the colloidal silicic acid which had been shaken out. After twenty four hours, the supernatant liquid was carefully decanted off and filtered through hardened filter paper. From the clear f iltrate , fifty cubic 'centimeters was removed , evaporated to drynes s , and weighed. ■ Res ults Fr itt Cone Color Condition Slaking Test olubility A 1 Thite Semi-fused Slightly turbid 4.2 % B 1 Wh i t e Semi-fused Cloudy 7 .0 C Jm White Sintered Milky white 7.0 D 01 Gray Semi -fused Slightly turbid 9 .8 E 01 Cream Semi-fused Fairly clear 4 .9 F 01 White Sintered Cloudy 11.4 G 02 Gray Semi-fused Slightly turbid 7 . 0 H 02 Cream Semi-fused Slightly turbid 3 .5 I OP. Wh i t e S intered Milky white 12.2 (6) Journal American Ceramic Society^ y 0 i. 3-1^20. P 15 3. 11 From the above table it can be seen that the refractor- iness increases with increase in potassium carbonate content. From the work done.it cannot be said just how much the condit- ion of fusion or the amount of potassium carbonate alone, affect the solubility, ’'here temperature conditions were the same, and the potassium carbonate wa-, present in smallest amount, the material had only sintered, was most refractory , and had the highest solubility. Probably if the fritt with high potassium carbonate content had only been sintered, its solubility would have been higher. The fritts were used in the condition des- cribed above. Development of the Body. The body was prepared especially for casting. As grind- ing was by far the most important feature in connection with the preparation , care was taken that the grinding was standardized and sufficient. Four ball mills having one and one half kilo- grams capacity each, with 3/4 inch flint pebbles to a depth of two and one fourth inches, were taken. All bodies having the same fritt composition were weighed out according to their numbers and positions on the triaxial diagrams. The extremes of each bod- y of similar fritt composition were added to + he ball mills. For example, the whole series of nine bodies was made up with the fritt A, then the whole series with the fritt B,etc. Bodies 1 and 2 were prepared in quantities of 9^5 grams each , a:^d bodies 6 and 9 of 12GC grams each. For bodies 1 and 2, 6 15 grams of distilled water were added, which made the specific gravity of the resulting slip equal to 1.6 . For bodies 6 and 9, 790 grams of water was added, which also made the slip spec- 12 ific gravity equal to 1.6. The correct specific gravity was chosen as 1.6, for on investigating , less water made the slip so heavy that it lumped in the mould, and more made it so thin that it cast slowly, and tended to crack in drying. The hall mills were put on the mill racks and run for 7 2 hours at 74 R.P.M. .making a total Of 319,680 Revolutions , per charge- This consumed a considerable amount of time. However, the resulting slip ran through a 150 mesh sieve like ' r ater,and was so fine no grit could he found with the tongue. After each extreme was ob- tained, the dry weight per fifty grams of slip was determined , and the extremes were wet blended to secure the intermediate bodies, numbers 3, 4, 5 , n and 8. The bodies were then cast into trial pieces- in plaster moulds. The moulds were provided with a rectangular depression two centimeters deep, ten by five centimeters at the bottom, and with sides inclined outward at an angle of(lO) ten degrees from the vertical. A portion of each extreme was made up into cones. Properties of the Casting Slips. Bodies with fritt A 5 , 6 , 7, 8 , 9 settled quickly and collected in the bottom of the receptacles on standing. 5,8,9, were the worst in this regard. The casting conduct was good. Drying was rapid. 5,6,^, showed a tend- ency to crack at the corners. B This class was much better. It did not te^d to f flocculate or settle.it dried rapidly, did not crack at all in drying, and was extremely tough when plastic. 13 Bodies with fritt C These cast very well and were fairly strong in the dry state. There was some tendency to f flocculation , especially with the high spar bodies. I> This group gave trouble in casting. It cracked badly, no matter what consistency the slip was made. 1,3, 4, 5 were especially bad. 5, 8, 9, or the high clay bodies, were fairly good. All showed a tendency to settle, the same as did A. E This group cast excellently. Number 4 was perfect in casting and drying conduct. With the exception of number 3 ,all dried safely , without cracking. The slip showed no tendency to fflocculate. E This series behaved the same as C. G This class was impossible to cast. Number 6 , par- ticularly , settled in granular form, making a uniform casting slip with it impossible without other electrolyte. All bodie3 cracked during drying, number 5 being the only one not to break . H All this group showed good casting and drying properties . The general behaviour was the same as for series B and E. I This group behaved similarly to C and E. There was tendency to crack in drying. All of the bodies except t-ose of high clay content , se ' tied in a jellylike mass very quickly. In addition to the above , it is significant that all the bodies of high potassium carbonate content formed a brown 14 scum on the surface of the piece when drying. When thoroughly dried the surface became slick, and could be peeled off. This slick scum was probably a form of potassium silicate. (7) After six or seven casts per mould with the bodies in series A,D,or G (the high potassium carbonate bodies), a scum formed on the surface of the moulds , which, rendered the latter use- less for further work. Those with medium potassium carbonate in the fritt were the best in casting and drying conduct. Dry ing Shrinkages . Note- "he original length pe r piece was ten centime ters. Fritt 1 2 3 Body 4 5 6 7 8 9 A 9 .7 9.8 9.8 9.8 9 .7 9 .8 9 .9 B 9 .7 9 .8 9.7 9 .7 9 .6 9 .6 9 .6 C 9.7 9 .6 9 .5 9 .7 9 .6 9 .6 9 .7 9 .7 D 9 .8 9 .7 9.7 9.8 S .8 9.7 E 9 .8 9 .5 9.5 9.8 9.6 9.7 3 .6 9 .6 F 9 .6 9 .6 9 .5 9 .7 9 .5 9 .6 9 .6 9.4 9 .5 G H 9.7 9 .6 9 .6 9 .5 9 .5 9 .7 9 .5 9 .4 9 .6 I 9 .8 9 .8 9 .6 9.7 9.5 9 .6 9.7 9 .6 9 .5 Those not given indicate pieces which would not dry safely. Shrinkage on the average amounted to 3 % .with 5 and 6 % in the case of high clay, and 2 % in the case of high fritt content . The color of the slip was a cream color, except the high feldspar bod y . which was pink. After drying , all were white. (7) Journal American Chemical Society ,1917. Vol. 39. Pp, 1173-1229. 15 Burning The cones made from the "body extremes were set in cone pats with standard cones and fired from cones five to ten. At cone five, vitrification was well Begun, and at cone twelve, none of the trials had melted , indicat ing a wide safe temperature range. The pieces were set in powdered calcined flint in "biscuit saggers. The saggers were wadded and placed in one of the coal fired test kilns. The kiln was fired to cone six in thirty hours. The cone reached in the top courses of saggers was cone six. In the hottm courses, cone five was reached. The fire boxes were then opened wide and full draft was turned on, in order to facilitate cooling. The Properties of the Burned Ware. After cooling, the saggers were unloaded and the flint was brushed from the pieces. The bodies showed the following proper- ties. Bodies A,D,and G were white, not translucent , and not thor- oughly vitrified. They had not deformed to that extent reached by some of the other bodies. The classes thus represented by their fritt compositions were generally unsatisfactory in their casting and drying conduct , also . ■The bodies with F and I fritt composition were somewhat similar to A,D,and G. The bodies which cast well, were thoroughly vitrified , and held their shape, were B3 ,B 7 , Cl , C4 , and CS. The very best appearance was made by E4,but this showed high total shrinkage. The bodies with E and H fritts had excellent properties generally , but showed high shrinkage and deformation. 16 The colors varied as follows, Bodies with fritt A were white with a creamy tint , especial- ly number 1, varying to a grayish white at numbers 5 and 9. Number 6 was perfectly white. Bodies with fritt B were white, except bodies 1 , 3 , 6, and 7 , which were white with a delicate creamy tint. Bodies with fritt C were white. Numbers 5, 8, and 9 showed the creamy tint. Bodies with fritt "D were all perfectly white. Bodies with fritt E all showed the faint creamy tint. The tint was especially pronounced in numbers 1,3, and 6 . Bodies with fritt E varied from a grayish to a creamy white while 5, 8, and 9 were perfectly white. Bodies with fritt G were all perfectly white. Bodies with fritt H were identical with E. Bodies with fritt I were identical with E. The translucency was not measured accurately , as the pieces were of relatively , but not exactly, the same thickness. Those showing the very best translucency were bodies E4 , E5 , e 6 , and E7 ; B3 and E7; Cl , C4 , and C6. Tne remainder were translucent when thor- oughly vitrified , but not as much so as the above. It can thus be seen that the bodies with high spar or medium high spar and high fritt content were most translucent .while the high clay bodies were the reverse. The triaxial diagram on the next page shows this more clearly. The deformation was not measured exactly. Most of the piec- es which were translucent and thoroughly vitrified .however , showed a tendency to draw up slightly at the ends. This was no doubt due partially to the method of setting. tr.u Clou n 18 Burning Shrinkages Hote- •The following data gives centimeters of length. The oricr- inal length per piece was ten centimeters. Britt Body 1 2 3 ') 4 5 6 7 8 9 A 8 -5 8.4 8.4 8.4 8.5 8.6 B 8.3 8.5 8.4 8.3 8.3 8.5 C 8.3 8.3 8.2 8.3 8.2 8.3 8.3 8.5 D 8.4 8.6 8.6 E 8.1 8.1 8.0 8.2 8.2 8.2 8.0 8.3 F 8.1 8.1 7.9 8.2 8.2 8.0 8.2 8.2 8.5 H TV 8.0 8 . 1 8.0 7.9 8.2 8.1 8.0 8.2 8.3 G I 8.1 8.1 8.2 8.2 8.1 8.3 8.3 8.5 The bodies with high clay and high potassium carbonate content in the fritt showed the least shrinkage. The high fritt content bodies showed the most shrinkage. The average burning shrinkage was eleven percent .making the total shrinkage fourteen percent . Selection of the Best Body. The body number B 7 was selected as being the most suitable body to represent the field because it most closely re- embled true belleek in appearance. It had excellent casting and drying conduct, very high translucency , low deformation , and good vitrification. In addition.it had the lowest total shrinkage cor- responding to the above properties , and was composed of a low amount of fritt, which would make it economical , to prepare on a commercial scale. I 19 IV. EXPERIMENTAL PROCEEDURE EOR THE COLOR. Realizing that pale pink and pale green are two of the most attractive colors when incorporated in a body, as for example, in jaspar .they were chosen as the color to he obtained in the belleek body. The body number B 7 was made up in quantity .and ground as before into slip at 1.6 specific gravity. To this body, the coloring was added in proportions of three percent and ten percent of the body weight. Pale pink is a difficult color to obtain at any time. ( 8) However, a reference was found which gave the following formula as one which would give a light pink in a parian body at Cone eleven. This stain was not fritted before incorporation in the body. Stain A formula 1 90 Fe 0 2 3 Al 2°3 Cr 0 9 2 3 Another formula for a light pink (9) was Stain B formula Sn0 o 149 SiOg Cr 2 0 3 CaO 60 .76 112 This calcined at Cone five in a fritt crucible in a gas pot furn- ace, and gave a pinkish purple color. This stain was given by Mr. Purdy as an underglaze pink, but it was thought probable that it would give the same color in the body. (8) Transactions American Ceramic Society. Vol. 15 »P . 14 1 . (9) Transactions American Ceramic Society. Vol.H,P-838 ■ 20 Pale green is not so difficult to obtain a3 pale pink, and more formulas are available. The following two formulas were selected as the "best. Stain C (1C) is given as a victoria green underglaze stain for U3e at from cones three to five. Accordingly , the stain was calcined at cone four in a method similar to that U3ed for stain B. Stain C formula Cr 2°3 18.6 Niter 24 .7 Flint ro o o Fluorspar 11.0 Whiting 22.0 CaS0 4 11.0 This gave a bright victoria green calcine. Stain D (4) is given as an underglaze color pale green for use on a body at cone six. The stain was prepared and calcined at cone five in a fritt crucible the same as Stain B. ) formula CaO 26 .0 Cr 2°3 11.4 Sn°g 149 Sl0 2 60 This stain gave a good pale green color after the calcination. ( 10) Transactions American Ceramic Society. Vol . 14 , P.430 . (11) Transactions American Ceramic Society. Vol. 11 , P.238. 21 The calcined stains were all ground in small color mill 3 to an .impalpable fineness. Then they were added to the body in portions of three and ten percent. The body with the stain added was mixed, readjusted with water to 1.6 specific gravity, and run on the ball mills for twenty four hours more, which mixed the color and body thoroughly , as well as additionally ground the color. The colored bodies were then cast in newly made plaster moulds of the same shape and size a3 was used previously for the body. Casting Properties. The colored body A cast excellently , dried without cracking, smoothly and uniformly , and did not harm the mould in the least. The body B al30 cast well, and dried without diff iculty ,but there was some firring on the mold with the high color content. The body C.with three percent color, cast excellently , but with ten percent color it tended to crack. However this proved wholly unsat isf actory for it not only firred the mold, but gave a greenish yellow stain to the mold for a depth of three fourths of an inch. In addition the color was unstable and rose to the top edges of the piece. This might have been obviated if the color stain had been well washed prior to its introduction in the body. The body D cast well with the low color content,but with the high color content it showed a tendency to crack, and the whole piece generally broke before it could be removed from the mould. Hone of the pieces deformed during drying. Cone trials and deformation bars were made from each body. The deformation bars were eight centimeters long, with triangular cross section seven tenths centimeters high. . 22 Drying Shrinkages. Body Amt . Stain % Amt. Stain /> .03 . 10 A 9.8 2 9 .7 3 B 9 .6 4 9 .6 4 C 9 .6 4 9 .6 4 D 9.7 3 9.7 3 Burning. The cones were placed in cone pats with standard cones, and were fired to cone twelve. They stood this heat without the least melting, or deformation. The trial pieces of "body A were packed in powdered calcined flint in wadded saggers. The deformation "bars were placed on sharp edges six centimeters apart .also in wadded saggers. The saggers were put in the gas kiln and fired to cone twelve, which "brought cone eleven down inside the saggers. An oxydizing atmosphere prevailed throughout the burn, except for a heating up period at the start. The trial pieces of bodies B,C,and D were placed in cal- cined flint in wadded saggers. The bars were placed on sharp edges 3ix centimeters apart, and also were placed in wadded saggers. The saggers were placed in a coal test kiln and fired to cone five in thirty hours. The cone3 were down inside the saggers. Burned Properties. The test pieces appeared as follows: The body A with three percent stain burned to an attract- ive pale green color. The piece was thoroughly vitrif ied , and burned without cracking or deforming. 23 The "body A with ten percent stain burned to a greener color than the other hut was not as attractive , and did not have as smooth a surface. Some blisters formed on the bottom of the piece. The body B with three percent color burned to a gray color with a pinkish tinge. The pieces were wholly unsatisfactory, although they burned without difficulty. The body B with ten percent color gave the same results. Both C bodies burned to a gray color with a greenish tint. A dirty greenish stain appeared around the top edges of the piece. The surface was poor, and the piece was not wholly vitrified. The body D with three percent stain gave a pale green color similar to that given by the body A. The color was a little more grayish, but very attractive. The piece was vitrified , and no trouble was had with cracking or blistering. Body D with ten percent color was impossible to cast. The body without the color burned with the same excellent properties as formerly. Burned Lengths. Body Amt . Stain % Amt . Stain of 7° .03 .10 A 6.2 16 8.35 13 .5 B 8.0 16 8. 15 15 C 8.1 15 8.4 12 D 8.2 15 The total shrinkage wa3 high , amounting to an average nteen and one half percent total. as against fourteen per cent total for the body alone. 24 The Deformations were as follows, The "bodies A were "bent one centimeters in six centimeters. The bodies B did not deform. The bodies C deformed one tenth of a centimeter in six . The bodies D deformed two tenths of a centimeter in six. y. SUMMARY OF RESULTS. The pink coloration was not developed at all. The green coloration was well developed in bodies A and D. Rone of thie colored bodies was translucent. The body D showed the be3t all around properties , such as good color, small deformat ion , and little shrinkage ,with a low cone. The body A when burned to cone five developed the best green color, but was not as thoroughly vitrified as the others. VI. GENERAL CONCLUSIONS. In the development of a belleek body, the points raised in the introduction , in regard to the properties of belleek, were all satisfied in the body B 7. Although a pale pink body was not developed , the pale green was satisfactory when color alone is considered. The pale green was almost a gray green in appearance. However, as far as investigated, introduction of even a small amount of color destroys the trans- lucency altogather. If further invest igation were to be done, the D body should be burned to cone eight instead of cone five .which might impart some translucency to it. The writer does not see how a pink color can be obtained, unless a good pink fritt can be produced which will retain the same color when added to the body. 25 VII. ACKMO^EDG'SMWT. The writer wishes to acknowledge his appreciation for the advice and assistance given by Professor Binns and Professor Parmelee during the preparation and performance of the work.