Orton cone temperature chart
This chart lists the Orton self-supporting cone temperature equivalents from cone 022 up to cone 10, in both Fahrenheit and Celsius. Because a cone measures heat-work, the same cone bends at a lower temperature when you fire slower and a higher one when you fire faster, so two heating-rate columns are shown.
Orton calibrates its cones to a heating rate of 108 F (60 C) per hour over the final 180 F of the firing. At that rate cone 06 bends at 1828 F, cone 04 at 1945 F, cone 6 at 2232 F, and cone 10 at 2345 F.
Source: Edward Orton Jr. Ceramic Foundation pyrometric cone temperature chart (ortonceramic.com).Cone temperatures, F and C
Self-supporting, regular cones. The first pair is the standard 108 F (60 C) per hour rate; the second pair is the faster 270 F (150 C) per hour rate. Use the column closest to your final ramp.
| Cone | Band | 108 F/hr | 60 C/hr | 270 F/hr | 150 C/hr |
|---|---|---|---|---|---|
| Cone 022 | Low fire | 1087 F | 586 C | 1094 F | 590 C |
| Cone 021 | Low fire | 1112 F | 600 C | 1143 F | 617 C |
| Cone 020 | Low fire | 1159 F | 626 C | 1180 F | 638 C |
| Cone 019 | Low fire | 1252 F | 678 C | 1283 F | 695 C |
| Cone 018 | Low fire | 1319 F | 715 C | 1353 F | 734 C |
| Cone 017 | Low fire | 1360 F | 738 C | 1405 F | 763 C |
| Cone 016 | Low fire | 1422 F | 772 C | 1465 F | 796 C |
| Cone 015 | Low fire | 1456 F | 791 C | 1504 F | 818 C |
| Cone 014 | Low fire | 1485 F | 807 C | 1540 F | 838 C |
| Cone 013 | Low fire | 1539 F | 837 C | 1582 F | 861 C |
| Cone 012 | Low fire | 1582 F | 861 C | 1620 F | 882 C |
| Cone 011 | Low fire | 1607 F | 875 C | 1641 F | 894 C |
| Cone 010 | Low fire | 1657 F | 903 C | 1679 F | 915 C |
| Cone 09 | Low fire | 1688 F | 920 C | 1706 F | 930 C |
| Cone 08 | Low fire | 1728 F | 942 C | 1753 F | 956 C |
| Cone 07 | Low fire | 1789 F | 976 C | 1809 F | 987 C |
| Cone 06 | Low fire | 1828 F | 998 C | 1855 F | 1013 C |
| Cone 05 | Low fire | 1888 F | 1031 C | 1911 F | 1044 C |
| Cone 04 | Low fire | 1945 F | 1063 C | 1971 F | 1077 C |
| Cone 03 | Low fire | 1987 F | 1086 C | 2019 F | 1104 C |
| Cone 02 | Low fire | 2016 F | 1102 C | 2052 F | 1122 C |
| Cone 01 | Low fire | 2046 F | 1119 C | 2080 F | 1138 C |
| Cone 1 | Mid fire | 2079 F | 1137 C | 2109 F | 1154 C |
| Cone 2 | Mid fire | 2088 F | 1142 C | 2127 F | 1164 C |
| Cone 3 | Mid fire | 2106 F | 1152 C | 2138 F | 1170 C |
| Cone 4 | Mid fire | 2124 F | 1162 C | 2161 F | 1183 C |
| Cone 5 | Mid fire | 2167 F | 1186 C | 2205 F | 1207 C |
| Cone 6 | Mid fire | 2232 F | 1222 C | 2269 F | 1243 C |
| Cone 7 | Mid fire | 2262 F | 1239 C | 2295 F | 1257 C |
| Cone 8 | High fire | 2280 F | 1249 C | 2320 F | 1271 C |
| Cone 9 | High fire | 2300 F | 1260 C | 2336 F | 1280 C |
| Cone 10 | High fire | 2345 F | 1285 C | 2381 F | 1305 C |
How to read it for a firing
Decide which cone your clay or glaze matures at (the bag or jar lists it), then look up its temperature in the column nearest your final ramp rate. That temperature is the peak your schedule should aim for. The schedule builder does this automatically: pick the cone and speed, and it reads the right column and lays out the ramps and holds to get there.
Sources
- Edward Orton Jr. Ceramic Foundation, Temperature Equivalent Chart for Orton Pyrometric Cones (self-supporting). ortonceramic.com.
- L&L Kilns, Orton cone chart reprint. hotkilns.com.
Frequently asked questions
Why does a cone have two temperatures?
A pyrometric cone bends from heat-work, the combination of time and temperature, not from temperature alone. Orton publishes the bending temperature at several heating rates. We show the standard 108 F (60 C) per hour rate and the faster 270 F (150 C) per hour rate. Fire slower and the cone bends cooler; faster and it bends hotter.
Which heating rate should I use to read the chart?
Use the column closest to the final ramp rate of your firing. Most studio cone-fire programs finish near 80 to 120 F per hour, so the 108 column is the right read for slow and medium firings. A fast program nearer 200 to 270 F per hour reads closer to the 270 column.
What are low, mid, and high fire?
Low fire is roughly cone 06 to 04 (earthenware and many commercial glazes). Mid fire is around cone 5 to 6 (most studio stoneware and porcelain). High fire is cone 8 to 10 and up (traditional stoneware and reduction work). The hotter you fire, the denser and less porous the finished clay.