Control
the heatwork
Pyrometric cones are used all over the world to monitor the firing temperature of ceramics - both in industrial kilns and small hobby kilns where a constant temperature is important for the quality of the fired final product. Orton pyrometric cones measure heat work, firing time and temperature. They are also an excellent indicator of the wear of the kiln spirals - they will let you know that subtle changes are taking place in the kiln, allowing you to take corrective action before they affect your products.
The practical application of the cones is aimed at verifying the thermal uniformity and repeatability of the firing at a specific curve. The final degree of cone deflection depends on the rate of temperature rise during the last 100°C (180°F) of the firing and the resulting end temperature. The degree of cone deflection after firing allows you to verify if your kiln delivers the expected amount of heat each time a specific firing curve is used, and that the heating is evenly distributed throughout the kiln (it is worth placing the cones in several different places in the kiln during one firing).
Select
APPROPRIATE ORTON CONES
The target temperature and the heating rate of the kiln during the final 100°C should be taken into account when selecting the appropriate pyrometric cone for monitoring your ceramic firings.
| Orton cone number | 15°C/h | 60°C/h | 150°C/h |
| 012 | 843 | 861 | 882 |
| 011 | 857 | 875 | 894 |
| 010 | 891 | 903 | 915 |
| 09 | 907 | 920 | 930 |
| 08 | 922 | 942 | 956 |
| 07 | 962 | 976 | 987 |
| 06 | 981 | 998 | 1013 |
| 05 | 1021 | 1031 | 1044 |
| 04 | 1046 | 1063 | 1077 |
| 03 | 1071 | 1086 | 1104 |
| 02 | 1078 | 1102 | 1122 |
| 01 | 1093 | 1119 | 1138 |
| 1 | 1109 | 1137 | 1154 |
| 2 | 1112 | 1142 | 1164 |
| 3 | 1115 | 1152 | 1170 |
| 4 | 1141 | 1162 | 1183 |
| 5 | 1159 | 1186 | 1207 |
| 5,5 | 1167 | 1203 | 1225 |
| 6 | 1185 | 1222 | 1243 |
| 7 | 1201 | 1239 | 1257 |
| 8 | 1211 | 1249 | 1271 |
| 9 | 1224 | 1260 | 1280 |
| 10 | 1251 | 1285 | 1305 |
For example, if you fire your works to a temperature of 1240°C, and you fire the last 100°C at 120°C/h, then Self-Supporting Cone 6 will be the target cone for you.
After defining the cone number needed to monitor your firing curve, select one cone number above and one below the target cone. The firing of three cones at the same time will allow you to accurately determine what conditions prevail in your kiln - whether it reaches the target temperature or, for example, it heats up more than indicated by the controller. After firing, measure the deformation of the target cone with the measuring template provided by Orton.
Measure
THE BEND
If the final position of the pyrometric cone after firing is between 25 and 75 degrees, this means that the temperature in your kiln at the given firing curve corresponds to the parameters of the pyrometric cone. If the cone did not bend at all, it means that the kiln did not reach the temperature assigned to the cone, and if it bent at a greater angle, it means that the temperature in the kiln was higher than indicated or the holding time was too long.
Related products
