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 Vol. XI. Jl 1.^ (,, 1VM4. N,.. 4S 
 
 [Kntereii as secDiul-cIass mattir Dicciiilicr 11, 1912, at the post office at 
 Urbana, Illinois, uiulir tl»c Ait of Aujjust 24, 1912.] 
 
 BULLETIN No. 21 
 
 DKPAR'rMKN'l- OF CI:R.\MIC\S 
 
 R. T. STl'LL, Acting l)iriit..r 
 
 DEFORMATION TEMPERATLRES () 
 SOME PORCELAIN GLAZES 
 
 in' 
 R. T. STULL AND W. L. HOW AT 
 
 A TYPE OF CRYSTALLINE GLAZE 
 AT CONE 3 
 
 c. c. RANI) .ANH H. (;. sriu Rl.rilT 
 
 I'L'HLisnKi) in iHi: rxn irsiia' or Illinois, i rilwa 
 
 1913-19 14
 
 ^^^J1 1JI5 
 
 AiitliDiizcl Ii.|)iint fr..ii. \..li \\l. IDU. Truiisiiclimis Aiiii-rit-uii ( cruiiiic S.Kii-l» 
 
 DEFORMATION TEMPERATURES OF SOME 
 PORCELAIN GLAZES 
 
 H. T. Srn.L AND W . I,, now AT. IKUANA. IM,. 
 
 The Liioiip of gla/.c's studied foiiipi'iscs ten lim-i/ iiit;il series 
 desiuiuitctl hy Icttci-s fi-oin A to .1. cacli sci-ics iM)ii>i->tinir 4»f ten 
 nieiiihci-s. The ^roup of one liiiiidi-t'd niciiihci-s (-{nci's tlic f(»|. 
 lf)\\iiii:- limits i-cpi-csciitcd hy the \'nnv ciinicr «rl;i/cs : 
 
 TABLE I— FORMULA OF CORNER GLAZE3 
 
 GLAZB 
 
 K„0 
 
 CaO 
 
 A'=0. 
 
 SiO. 
 
 A-l 
 
 . :\ 
 . :> 
 
 O.T 
 0.7 
 0.7 
 0.7 
 
 0.40 
 0.40 
 . 85 
 0.85 
 
 2 
 
 A-10 
 
 f) 5 
 
 T-1 
 
 2 
 
 T-10 
 
 6 5 
 
 
 
 TABLE II— BATCH WEIGHTS 
 
 BKAMIY- 
 
 Wl.NE 
 
 FELIibP.\R 
 
 V.sv. No. 
 
 20 BALL 
 CLAY 
 
 .\1,(0H), 
 
 A-l 
 
 A-10 
 
 J-i 
 J-io 
 
 167.4 
 167.4 
 167.4 
 167.4 
 
 70.0 
 70.0 
 70.0 
 70.0 
 
 1 2 . ;» 
 
 12.9 
 12.9 
 70.9 
 
 12.9 
 12.9 
 12.9 
 70.9 
 
 270.0 
 216.0 
 
 ro.2 
 
 Different inenilx'i's in the ;^i"oup wcw made 1)\" molecular 
 l)lendin<i- of the four e.xti-eiiies. Tliese were apidied to Itisipie 
 wall tile, .set in safrgers in a down draft kiln and Iturned to eone 
 !) in 40 hours. 
 
 Cones were also made Ifnm the jrlazes and theii- deforma- 
 tion temperatures determined in a platinum resistance furnaee. 
 the temperatures bein^ measured hy a platinum. |)latinum-rhod- 
 iuiii tliennocouple and a Leeds-Xorthiup direct leadiii'^' [xiteii- 
 tiometer. faeeurate to Il^C).
 
 4 DEFORMATION TEMPERATURES OF GLAZES 
 
 The time-temperature curve followed in all determinations 
 is shown in Fig'iire 1. The temperature was raised to 1200 'C. 
 in 120 minutes. Beyond this the te:nperature rise was 2io de- 
 crees per minute. A number of deformation tests made on du- 
 plicate Seger cones gave the following results: cone 4— 1212' C. 
 cone 6— 1255=C., cone 8— 1290=C. 
 
 Deformation-temperature readings were made on two or 
 more cones of each glaze. The variation was rarely over 5 = C., 
 and in the majority of tests, duplicate cones gave the same tem- 
 perature readings. 
 
 TABLE III — DEFORMATION TEMPERATURES COVERING THE LIMITS 
 
 
 
 0.3 KcO 
 0.7 CaO 
 
 ' 0.40 to 0.85 .\1:0.. : 2.0 to 6.5 SiOr: 
 1 
 
 
 
 
 1 1 1 1 1 i 1 1 1 1 
 
 1 2l3 4|5l6 7|8|9jl0, 
 
 MOLSCCLES 
 AlA 
 
 T 
 
 
 . 1277 1246 
 
 1232 1235 1247 1252 1248 1260 1267 1265 
 :228 1230 1240 1235 1245 1247 1250 1252 
 
 0.85 
 
 i 
 
 
 . 1275 1240 
 
 0.80 
 
 H 
 
 
 . 1272 1245 
 
 1232 1230 1230 1232 1235 1235 1245 1245 
 
 0.75 
 
 G 
 
 
 . 1272 1240 
 
 1228 1228 1232 1232 1233 1237 1235 1247 
 
 0.70 
 
 F 
 
 
 . 1267 1238 
 
 1225 1225 1225 12251228 1235 1235 1245 
 
 0.65 
 
 E 
 
 
 . 1232 1225 
 
 1225 1222 1220 1225 1228 1235 1245 1245 
 
 0.60 
 
 D 
 
 
 . 1230 1225 
 
 1225 1227 1230 1230 1240 1245 1248 1252 
 
 0.55 
 
 C 
 
 
 . 1232 1228 1228 1228 1228 1230 1240 1248 1252 1255 
 
 0.50 
 
 B 
 
 
 . 1235 1230 1228 1233 1235 1245 1254 1252 1257 1270 
 
 0.45 
 
 A 
 
 
 . 1232 1232 1240 1245 1245 1255 1255 1268 1272 1277 
 
 1 i 
 
 0.40 
 
 M 
 
 LECCLES 
 Si0„ 
 
 III I'll 
 2.0 2.5| 3.0 3.5l 4.o: 4.5| 5.0' 5.5| 6.0 6.o' 
 
 ! ! : ' ' ' ' 
 
 
 The average temper:iture readings for two or more cones of 
 each glaze of the group are given in Table III. The results of 
 the burn and the iso-deformation lines are represented graphi- 
 cally in Figure 2, the deformation-temperature being indicated 
 in degrees centigrade on each line. 
 
 The RO is constant for all glazes. The molecular variations 
 of SiOj are plotted along the abscissa and the molecular varia- 
 tions of Al.,0.. on the ordinate.
 
 DKFOKMATlUN TK.Ml'KKATl Kl S OF OLAZtS 
 
 ^ 3ifaLWt/3cJIV^J.
 
 6 DEP'OKMATION TEMPERATl'RES OE GLAZES 
 
 In the lower right corner are the devitrified ghizes between 
 the limits : 
 
 RO, 0.4 ALO,, 5.0 SiO, 
 RO, O.4ALO3, 6.3 SiO, 
 RO. O.6ALO3, 6.5 SiO, 
 
 In the h)Aver portion of the devitrified area the glazes were 
 crazed. In the center of the field are the bright glazes which 
 were considered matured. Bright glazes which were crazed are 
 found in the lower left corner within the limits : 
 
 RO, 0.4AL,O3. 2.5 SiO, 
 RO, O.4AUO3, 2.0SiOo 
 RO, 0.5 AlA, 2.0 SiO, 
 At the left of the field a small group of matured mats are 
 found between limits : 
 
 RO, 0.55 AL.O^, 2.0 SiO, 
 RO, 0.70 ALO3, 2.0 SiO, 
 RO, 0.65 ALO.,, 2.5 SiO, 
 
 In the upper i)art of the field the glazes wei'e uiuler fired. 
 
 The ditf'erence between max and iiin deformation tempera- 
 tures is 57° C, the softest one deforming at 1220^0. having the 
 formula, RO, 0.6 ALO,,, 4.0 SiO,. The member at the upper left 
 corner (RO, 0.85 ALO.,, 2.0 SiO.) and the one at the lower right 
 corner (RO, 0.4 ALO,,, 6.5 SiO,) deformed at the max tempera- 
 ture 1277° C. 
 
 Each horizontal series may be considered as being com- 
 posed of the components, glaze a.nd SiO.. The broken line 
 CD passes through the deformation-euteetic of each of the ten 
 glaze — SiOo series. In a vertical direction, consider each series 
 made up of glaze and ALO3, the dotted line EF represents the 
 deformation-euteetic axis of the ten glaze— ALO., series. 
 
 These two axes (CD and EP) cross at the point of lowest 
 deformation temperature (group eutectic). Its deformation 
 temperature is ten degrees higher than the indicated tempera- 
 ture of Seger cone 4. The glazes whose formulae correspond to 
 cones 4, 5 and 6 deformed at 1228" C, 1240° C and 1245° C re- 
 spectively.
 
 DEl-'ORMATIOX THMPERATIRKS OK (ihA'AKS 
 
 Tlie line AB is the hip-h ^'loss axis plotted aceording to the 
 appcai-aiiee of the srlnzed trials. The }rh)ss axis follows roughly 
 parallel to the g:laze-SiO.. deforniation-etiteetie axis up to the 
 iiroup eiitectic. Beyond this point it deflects and follows along 
 
 Me>i.ecaL£s 
 
 CO/^£ A'//Vf BUffN 
 
 CaAfSTANT\ 
 
 f .3/^0 
 
 ./C0O 
 
 psy/r/?/F/£P 
 c/PAzeo 
 
 psyiTffiFieo 
 
 the glaze- ALO3 deformation-eutectic axis. The group deforma- 
 tion-euteetic lies near the center of the field of best glazes, and 
 the quality of the glazes decreases in all direction away from 
 this eutoctic point. The general formulae of the best glazes as 
 shown bv the ti-ials are:
 
 DEEOfiMATIOX TE:\IPERATURES OF GLAZES 
 
 E.O-0.60 ALO3 4.0 SiO, Deformation temp. = 1220 = C. 
 
 RO-O.55ALO3 3.5 SiO, Deformation temp. = 1227°C. 
 
 IIO-0.55 ALO3 4.0 SiO, Deformation temp. == 1230^C. 
 
 EO-O.6OAI0O, 3.5 SiO, Deformation temp. = 1222°C. 
 
 T/?AN3. ^M. Cf/?. 30C. yot. X^/ 
 
 3 TOLL & HOl^/AT 
 
 3e> 4Z 
 
 MOL£CCi.£S 3,0, 
 
 
 30t//VO 
 C/?AZeD 
 
 The ditferenee between tlie deformation-ten] peratures of 
 tlie.se glazes and the temperature to which they were fired (cone 
 9) is 80^ C to 90" C, or a difference of 4 to 4V, cones. For the 
 purpose of comparison the iso-deformation temperature lines are 
 plotted on the field of porcelain glazes burned at cone 11 and
 
 DEFORMATION TK.MI'KHATl KKS OF OLAZKS 9 
 
 l»i-cvi(iusly ri'portfd.' I-Muuk' ^1. Tin' liiirli irluss ;ixi.s C^'l' lies tn 
 the riurht of the glaze-SiO. (Miti-ctic axis ami crossos the yrlaze- 
 ALO;, euteetif axis eiose to \hv ciitcftif luciiiltfi- of th*- jrroijp. 
 The best glazes in this «rroup are foinid in close pi-dximity t<» the 
 group euteeti*'. the saiue as in tlie cone :• Imni. Not only does 
 the group eutwtie lie near the eenter of the are;i of hest glazes, 
 but it is also located at a safe distance away fi-oni devitrili«'ation, 
 cra/inu, matiiess and innnatuiity. 
 
 t rraniic I.almratnrifs, 
 
 rniversitv of Illiiiuis. 
 
 ' liitliifiiccs of variaMe Sibca and Aluiniiiu on I'orcclain (;la/.rs of Constant RO, 
 Triiii.t. Amer. Cer. Soc, Vol. xiv, pp. 62-70.
 
 A TYPE OF CRYSTALLINE GLAZE AT CONE 3 
 
 C. C. RAND AND H. G. SCHURECHT, URBANA, ILL. 
 
 The glazes under consideration are of a type designed to 
 mature about «one 3 to 4. The ALO. is maintained constant 
 throughout at .05 equivalent and is introduced as Pikes No. 20 
 English liall clay. In general the group resembles Worcester's^ 
 best raw clay glaze. ITis formula was 
 
 0.331/3 Na,0 ) 03A1O ( 1-60 SiO, 
 
 0.662/3 ZnO ( - -^'^ ^-' 1 0.20 B,03 
 
 He concludes, however, that .05 ALO., generally seems the most 
 favorable and that many German formuhp call for this amount. 
 A group of 36 glazes was made with a view to determine the 
 effect of varying ZnO against XaJ) along the ordinate, and rutile 
 against flint along the al)scissa. 
 
 
 /=/o./ 
 
 
 .OSCaO 
 
 £ 
 D 
 C 
 S 
 
 
 ^SZ^O> jo3^0j \o.S770^ 
 
 The arrangement of the grou}) with the formulae of the four 
 cornei-s are shown in Fig. 1, the vertical series being designated 
 by numbere. the horizontal series by lettei"S. 
 
 Two frits of the following compositions were used : 
 
 No. 1 
 0.25 Na,0 \ 
 
 0.70 ZnO 1 0.30 B.Og ' 1.4 8iO, 
 0.05 CoO 
 
 - Vol. X Trans. Amcr. Cer. Soc, p. loO. Function of .\Iumina in Ciistallino Glaze.
 
 C'KVSTAI.l.INi: < LAZi: AT ( UNK '^ 11 
 
 No. 2 
 
 0.45 ZiiO Ui.:iO IV.o, ; 1.4 SiO, 
 O.Of) ('<)() I 
 
 Tlu'Sf \V(M'(' cju'li iiitiiii.Mlcly iiiixril ••iiitl ^nuiii.l in s!ii;ill luill 
 iiiill.s. i"\i,s('(l. (|ii<Mi('hc(l ill wMlcr. tli'ii-.l .iikI irntniKl to pass 80 
 iiicsh sieve. 
 
 Tile four corner L-'ia/es were Lrrouml wet until they pa.s.se(l 
 ll'ii iiiesli sieve, and the I'eniainiii'^- <:la/.es Mended from tlieui in 
 nioleeulai- pr<iportions. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 ^ 
 
 ■\ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 V 
 
 
 ^ — , 
 
 
 
 
 
 
 
 
 
 
 
 
 ■^ 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 -- 
 
 
 
 ^ 
 
 
 
 
 l... 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 — 
 
 ^ M 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 N 600 
 \ 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 r-^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1? 300 
 
 
 
 — 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 i 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 L 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 
 / 
 
 ' — : 
 
 - 
 
 
 »• -i 
 
 " 
 
 
 ^ i 
 
 s 
 
 7//7 
 
 ' 7 
 
 »//7 
 
 J ? 
 
 ■3 
 
 ? 7 
 
 t"' > 
 
 ^ l 
 
 *" /< 
 
 * ' 
 
 7 M 
 
 ' 
 
 ' • 
 
 The jilazos were applied to t\vo sets of l)iscuit tile by dip- 
 ping;, and burned to eone :{ in T) hour.s in a round, down-draft, 
 open-fired oil kiln. The fires were i)ut out when the finishing 
 temperature wa.s reached and the kiln allowed to e<M>l with the 
 damper elostnl. 
 
 The results were not satisfactory, as only a few crystalliuQ 
 patches appeai-ed. These patches increased noticeably a.s the con- 
 tent of ZnO increased. Ilii-h ZnO also appeared to irive a deeper 
 blue as w(.id<l l>e expected. V. '■'> sli<iwei| the most crystallization.
 
 12 
 
 CRYSTALLINE GLAZE AT COXE 3 
 
 I 
 5 
 
 I 
 
 
 X 
 
 ^ 
 
 ^ 
 
 > 
 
 ^ 
 
 ^i 
 
 ^^4^1^ C^ ^
 
 CRVSTAI.I.lXi; (iLAZK AT CONK .'i 13 
 
 The fiiilmv to ol)taiii Lr«M)d results \va.s uttiihiited to too rapid 
 (HM^ling, t-oo thin co^itiutr of the irlaze. and i)erhai)s slight uiidor 
 t)iii'iiiii<r. 
 
 Next two sets of trials were dipjjeil, eai'e heiiiir t^lkeu to ob- 
 tain a thiek eoatiiiir of the fjlaze. and burned in the same kiln t« 
 eone 4. folIowiiiL;' the heatiuir mid eooliuLr curve shown in Fi<;ure 
 2. The pyrometer showed a teiiii)ern1ui'c of 1170 (', when oone 
 4 went down. 
 
 Fi'oni a ei-ystalli/.ation standpoint, the i-esults. Ki^'. 3, were 
 hi'^ddy satisfaetory. Kvery jilaze showed a lai-i^*- number of crys- 
 tals and in many eases was a solid mass of crystals of varyin«( 
 sizes. The vai'iation of ZiiO and Xa^.O seems to have little, if any, 
 effect upon either crystallization or color. 
 
 Increase in TiOo has a marked effect upon both. As TiO„ 
 increase<i the crystals became smaller, and more nnin« imus, most 
 of the hiofh rutile glazes consi.sting of a mass of small interlocking 
 crystals. At 0.0 TiO. and at 0.1 TiO., a good blue color is shown, 
 but fixnn 0.1 TiO^ up, the blue is partially and in some cjus(« al- 
 most totally absent. Bronze patches are (piite pronnnent. due 
 possibly to iron impurities in the rutile. 
 
 The two sets of trials are very ncai'l\' ideiitieaj. (JIaze K '.i, 
 with the foi-mula 
 
 0.30 Na.O 
 0.65 ZnO 
 0.05 OoO 
 
 0.05 Al.,(), J 1.8 SiO, 
 0.80 H.,0.. I 0.2 TiO., 
 
 aiiviin appears to contain the most crystals and for this reason 
 was selected as the glaze to use in making di-aw trials with a view 
 to noting different stages of crystallization. 
 
 The glazes were dipped and burned in the same manner as 
 before, a number of ti'ials of K 3 being jjlaced where Ihey could 
 l)e drawn. . One was drawn at the finishing point, and one evei-y 
 20 as the cooling progressed. The thii-d trial drawn showed 
 crystals around the edges. The amount of crystallization in- 
 creased steadily for four trials. The; lU'.xt ti'ial at 1030"C showed 
 a very great iiu'rease, the glaze consisting <d" a mass of crystals. 
 It is posible that this is du<' to the crystallization of an eutectic.
 
 14 
 
 CRYSTALLINE GLAZE AT CONE 3 
 
 That is, the oompound forming the crystals shown fimt continued 
 crystallizing out until the melt reached the composition of the 
 eutectie mixture, when the whole mass crystallized. (Fig. 4.) 
 
 TffA/vs. Am. C£/^. Soc. l^o/L . X)// /^/o.^. /^AA/c & Sc^u/f^c^r 
 
 //70''C 
 
 /OYCC 
 
 /05O°C 
 
 /OJO°C 
 
 /o/o °0 
 
 One set of trials was i)hu>ed on edge in this last burn. They 
 failed to show as much crystallization as those lying down, as the 
 glaze had run otf to a great extent. However, good results were 
 obtained on two small vases to which the glaze had been applied 
 in a very thick coat, though here also, much of the glaze had been 
 lost.