Kiln Firing Temperatures Explained: What Every Potter Needs to Know
One of the first things that trips up new potters is the cone system. You go to buy clay and it says "cone 6." You look at a glaze and it says "cone 04." You look at a kiln and it lists a maximum temperature of 2300°F. How do these all connect?
Here's a clear explanation of how kiln firing temperatures work — and what it means when you're choosing your kiln and materials.
What Is a "Cone"?
Pyrometric cones are small pyramid-shaped ceramic pieces designed to melt and bend at specific temperature-time combinations. When a cone bends to its prescribed angle, it tells you the kiln has reached the right "heat work" — a combination of both temperature and time at temperature that determines how completely your clay and glazes have matured.
The Orton Cone system is the U.S. standard. Cones are numbered from 022 (the lowest) up through 01, then from 1 up to 10 (and beyond). Confusingly, the lower the two-digit number with a zero (022, 06, 04), the cooler the temperature. Once you pass cone 01 and get to cone 1, the numbers increase with temperature.
Low Fire, Mid Fire, High Fire
Low fire (cone 022–cone 1, approximately 1100°F–2100°F): Used for earthenware and terra cotta. Glazes are bright and often have a glossy finish. Most commercial tile, red clay pots, and majolica are low fire. Any basic 120V kiln can reach these temperatures easily.
Mid fire (cone 2–cone 6, approximately 2150°F–2232°F): The sweet spot for most studio potters. Cone 6 stoneware is durable, food-safe when properly glazed, and gives rich color results. Most electric kilns are rated to at least cone 6, and many reach cone 8.
High fire (cone 8–cone 10+, approximately 2300°F–2350°F+): Traditional stoneware and porcelain territory. Cone 10 is considered the classic high-fire range, producing very dense, durable ceramics. Achieving cone 10 requires a more powerful kiln — the Evenheat High Fire 2327 and Olympic MAS2327HE are built for this range.
Quick Reference Cone Temperature Chart
How to Match Your Kiln to Your Work
Always check both your clay body and your glazes. They need to be compatible — a cone 6 glaze on a cone 10 clay that was only fired to cone 6 is going to result in underfired clay. And a cone 10 glaze applied to earthenware and fired to cone 6 won't melt properly.
When buying a kiln, look at the maximum rated temperature, and give yourself margin. If you plan to fire to cone 6 regularly, don't buy a kiln that barely reaches cone 6 — buy one rated to cone 8 or 10 so you're not running the elements at their limit every firing.
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