What Does 'Cone 6' Mean?

You’ll hear it everywhere in ceramics:
"Is this Cone 6 clay?"
"I glaze fire to Cone 6."
"Careful, this only goes to Cone 10!"

But what exactly is a cone — and why should you care?

The Quick Version:

Cone 6 refers to a specific level of heatwork in a kiln — a combination of temperature and time — not just a number on a thermometer.

So What’s a “Cone”?

A pyrometric cone is a little triangle of ceramic material that melts at a precise point. Potters place these cones inside the kiln to physically measure when the right amount of heatwork has occurred.

Think of it like baking a cake: it’s not just about how hot the oven gets — it’s about how long it’s hot. Cones track both.

What Does Cone 6 Actually Mean?

• Cone 6 is typically around 1220–1240°C (2228–2264°F) in an electric kiln.

• It's the standard mid-fire temperature used in many studios, including ours.

• It’s high enough to vitrify stoneware clays and melt most glazes beautifully.

Why Cones, Not Just Thermometers?

Kiln thermocouples only tell you air temperature. But clay and glaze respond to total heat absorbed, which depends on:

• How fast you heat up

• How long you hold temperature

• Where your pot sits in the kiln

Cones give a more accurate, physical read of whether your pot is “done.”

Cone 6 vs Cone 10 vs Cone 04?

Here’s the basic scale:

Cone°C (approx)RangeNotes04~1060°CLow-fireBisque, earthenware glazes6~1230°CMid-fireStoneware, most studio glazes10~1300°CHigh-firePorcelain, gas reduction firing

Why It Matters to You:

• Use clay and glazes rated for the same cone.

• Don’t mix Cone 6 glaze on Cone 04 clay — it could melt or crack.

• Cone mismatches are a common cause of studio mishaps!