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Temperature Equivalents for Orton Standard Pyrometric Cones

Cone #	Large cones rate of ascention		self sup cones rate of ascension		small cones rate of ascension
Cone #	150C	270F	150C	270F	150C	270F
022	-	-	590	1094	625	1157
021	611	1132	617	1143	646	1195
020	634	1173	638	1180	664	1227
019	685	1265	686	1267	712	1314
018	725	1337	727	1341	755	1391
017	752	1386	755	1391	785	1445
016	784	1443	785	1445	825*	1517*
015	807	1485	809	1488	843*	1549*
014	831	1528	833	1531	880	1616
013	859	1578	861	1582	892	1638
012	864	1587	866	1591	900	1652
011	884	1623	886	1627	918	1684
010	894*	1641*	896	1645	919*	1686*
09	923*	1693*	925	1697	955*	1751*
08	955*	1751*	957	1756	983*	1801*
07	984*	1803*	986	1807	1008*	1846*
06	999*	1830*	1001	1834	1023*	1873*
05	1046*	1915*	1048	1918	1062*	1944*
04	1060*	1940*	1062	1944	1098*	2008*
03	1101*	2014*	1103	2017	1131*	2068*
02	1120*	2048*	1122	2052	1148*	2098*
01	1137*	2079*	1139	2082	1178*	2152*
1	1154*	2109*	1156	2113	1179*	2154*
2	1162*	2124*	1164	2127	1179*	2154*
3	1168*	2134*	1170	2138	1196*	2185*
4	1168*	2167*	1187	2169	1209*	2208*
5	1196*	2185*	1204	2199	1221*	2230*
6	1222*	2232*	1222	2232	1255*	2291*
7	1240*	2264*	1245	2273	1264*	2307*
8	1263*	2305*	1268	2314	1300*	2372*
9	1280*	2336*	1280	2336	1317*	2403*
10	1305*	2381*	1305	2381	1330*	2426*
11	1315*	2399*	1315	2399	1336*	2437*
12	1326*	2419*	1326	2419	1355*	2471*
13	1346*	2455*	1348	2458	1349	2460
14	1366*	2491*	1384	2523	1398	2548
15	1431*	2608*	1428	2602	1430	2606
16	1473*	2683*	1475	2687	1491	2716
17	1485*	2705*	1487	2709	1512	2754
18	1506*	2743*	1508	2746	1522	2772

*Temperature equivalents as determined by the National Bureau of Standards by H.P. Beerman (see Journal of the American Ceramic Society, Volume 39, 1956). Large cones at 2 inch mounting height, Small & PCE cones at 15/16 inch.

1. The temperature equivalents in this table apply only to Orton Standard Pyrometric cones, heated at the rate indicated in air atmosphere.

2. The rates shown were maintained during the last several hundred degrees of temperature rise.

3. Temperature equivalents are not necessarily those at which cones will deform under firing conditions different from those of calibration determinations.

4. For reproducible results, care should be taken to insure that the cones are set in a plaque with the bending face at the correct angle of 8 degrees from the vertical with the cone tips as a uniform height above the plaque. Self supporting Cones are made with the correct mounting height and angle.

For more information on pyrometic cones visit www.ortonceramic.com

Orton pyrometric cones have been the standard of the ceramic industry since 1896. They are elongated pyramid shapes made of clay and various fluxes. Each cone number will melt (bed) at a known temperature, when heated at the rate per hour as indicated on the temperature equivalent chart. Cone numbers can be confusing for the beginner. For example: cone 06 is a lower temperature then Cone 6. Generally cone 022 through 017 are used for china Paints, Lusters, Metallics, and Decals, Cone 07 though 01 for Bisque and Low Fire Glazes, and Cone1 through 10 for Porcelain and Stoneware. Refer to chart for proper selection.

Large Cones
These 2” high comes are for use inside the kiln firing chamber. Usually three cones are used, one for the intended firing temperature, one lower and one higher. Example: for a Cone 06 firing use Cone 07 as the guide cone (lower), Cone 06 as the firing cone and Cone 05 (higher) as the guard cone. Cones should be set in a cone plaque or holder, then places inside the kiln in a location where they can be viewed through the peephole of the kiln. When the guide cone starts to bend it serves as a warning that the firing process is approaching completion. When the tip of the firing cone touches the plaque, the kiln is to be turned off. If the guard cone bends the ware has been over fired.

Small Cones and Bars
Small (junior) Cones measure 1 1/8 inches high and Bars are 1 inch long. Both are used in Dawson Kiln-Sitter although small cones can also be used in cone plaques. When the selected Cone or Bar melts, it activated a trigger which turns the kiln off. The use of a kiln-sitter does not illuminate the use of large cones as they should be used as “witness” cones to determine temperature variation throughout the kiln and the accuracy of the kiln-sitter.

Self Supporting Cones
A unique cone that does not require a holder.

Cone Plaques
The use of plaques and holders assures that cones are positioned at the correct angle to obtain the most accurate indication of proper firing. Plaques for large cones are available in two and four holes scored bars. They may be fired up to Cone 34 and are not reusable. Small (junior) cone plaques have four holes and fire up to Cone 16.

Temperature Equivalents for Orton Standard Pyrometric Cones

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