Orton cone chart
Orton Standard Temperature Equivalent Chart
*(when heated at 150oC/hr)
| Cone No. |
Centigrade |
Fahrenheit |
Visual Color |
| 022 |
600 |
1112 |
Dull Red |
| 021 |
614 |
1137 |
|
| 020 |
635 |
1175 |
|
| 019 |
683 |
1261 |
|
| 018 |
717 |
1322 |
|
| 017 |
747 |
1376 |
|
| 016 |
792 |
1457 |
|
| 015 |
804 |
1479 |
|
| 014 |
838 |
1540 |
|
| 013 |
852 |
1565 |
|
| 012 |
884 |
1623 |
Cherry Red |
| 011 |
894 |
1641 |
|
| 010 |
900 |
1652 |
|
| 09 |
923 |
1693 |
|
| 08 |
955 |
1751 |
Orange |
| 07 |
984 |
1803 |
|
| 06 |
999 |
1830 |
|
| 05 |
1046 |
1914 |
|
| 04 |
1060 |
1940 |
|
| 031/2 |
1080 |
1976 |
|
| 03 |
1101 |
2014 |
|
| 02 |
1120 |
2048 |
|
| 01 |
1137 |
2079 |
|
| 1 |
1154 |
2109 |
Yellow |
| 2 |
1162 |
2124 |
|
| 3 |
1168 |
2134 |
|
| 4 |
1186 |
2167 |
|
| 5 |
1196 |
2185 |
|
| 6 |
1222 |
2232 |
|
| 7 |
1240 |
2264 |
|
| 8 |
1263 |
2305 |
|
| 9 |
1280 |
2336 |
|
| 10 |
1305 |
2381 |
White |
| 11 |
1315 |
2399 |
|
| 12 |
1326 |
2419 |
|
| 13 |
1346 |
2455 |
|
*When heated faster than this, cones will go down at a higher temperature; when heated slower, cones will go down at a lower temperature. This is due to the 'heatwork' on the clay.
What is 'heat work'?
Pyrometric cones register the 'work' done by the heat we add to the kiln while firing. This 'heat work' is what makes the glaze on your pot mature, not the temperature. Thus, pyrometric cones which measure the heat work offer the best means of monitoring a firing. Pyrometric cones are designed to melt and bend at specific firing values which are listed above. The cones must be placed in a spot in the kiln that you can see through a peephole during the firing.
Warning! Do not view cones above earthenware temperature with the naked eye. It could cause cataracts. It is safe to view through welders goggles however sunglasses are not safe as they filter out UV, but not infra-red, which is the damaging wavelength.
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