Cone Temperature Charts
|Cone number||Orton Cones
Final temp in degrees F at ramp rate of 27 degrees F/hr
Final temp in degrees F at ramp rate of 108 degrees F/hr
Final temp in degrees F at ramp rate of 270 degrees F/hr
|Type of work done at these temps|
|10||2284||2345||2381||High Fire Ceramics|
|7||2194||2262||2295||Mid Fire Ceramics (Cone 5-6 most common)|
|1||2028||2079||2109||Low Fire Ceramics (06-04 most common)|
|017||1301||1360||1405||Overglaze / China Painting|
In standard firing, cones of the correct number are placed around the kiln and are watched. When the cones fall the kiln is turned off. This works the same for gas and electric kilns.
Electric kilns with electronic controllers (such as the Skutt KilnMaster series) have a thermocouple which continuously measures the temperature, records it over time, and shuts off the kiln when the appropriate heat absorption has been met. So if the ramping temperature is fast, the kiln will go to a higher temperature before it turns off than if the ramping temperature is slow (thus allowing the clay to absorb more heat along the way.) The final temperature is most affected by the rate of temperature increase over the last 300 to 400 degrees of firing.
Note: Think of the 0 in a cone number as meaning "minus". So 06 is much cooler than 6 because it is like a "minus 6".
Typcically it takes 15-25 minutes for a cone to bend once it starts. This depends on the cone number. The cone bends slowly at first but once it reaches the half way point it bends quickly. When the cone tip reaches a point level with the base, it is considered properly fired.
If a cone is soaked at a temperature near its equivalent temperature, it will continue to mature, form glass and bend. The time for the cone to bend depends on several factors and as a general rule, a 1 to 2 hour soak is sufficient to deform the next higher cone number. A soak of 4 to 6 hours will be required to deform two higher (hotter) cones.