Kiln Firing Temperatures: A Complete Guide for Potters

Quick answer: Kiln firing temperatures are measured in cones, ranging from cone 022 (about 1087°F) to cone 14 (about 2552°F). Bisque firing typically happens at cone 04–06 (1828–1945°F), while glaze firing depends on your clay body—low-fire at cone 06–04, mid-range at cone 5–6 (2167–2232°F), and high-fire at cone 9–10 (2300–2381°F).

Get the temperature wrong, and the work fails. Underfire, and your piece stays porous and weak. Overfire, and it slumps, bloats, or sticks to the shelf. Every clay body has a window. Hit it, and you get strength, color, and a finish that lasts.

This guide breaks down the temperatures that matter—from raw clay to finished glaze. You’ll learn how cones work, which firing range fits your clay, and how to move through bisque and glaze firings with confidence.

Let’s start with the language of heat.

How are kiln temperatures measured?

Potters don’t fire by temperature alone. They fire by cones.

A pyrometric cone is a small, slender pyramid made from ceramic material. It bends and melts at a specific combination of heat and time—called heat work. When the cone tip touches the shelf, your target is reached. This matters because two kilns can hit the same temperature yet do different amounts of work on the clay.

Cones run on a numbered scale. The system can confuse beginners, so here’s the logic:

• Cones with a zero prefix (022 to 01) are low temperatures. The higher the number, the cooler the firing.
• Cones without a zero (1 to 14) are high temperatures. The higher the number, the hotter the firing.

So cone 022 is the coolest. Cone 14 is the hottest. Cone 06 is cooler than cone 6—a difference of roughly 400°F. Mixing those two up ruins a kiln load.

Most studios use a pyrometer to track temperature in real time. But the cone makes the final call.

What are the firing ranges for different clay types?

Clay is not one material. It’s a family, and each member has its own limit. Fire past that limit and the clay deforms. Stop short, and it never matures.

Three ranges cover most studio work.

Low-fire clay (cone 06–04)

Earthenware falls here, firing between roughly 1828°F and 1945°F. It stays slightly porous even when mature, which is why low-fire pottery often needs glaze to hold water. The payoff is color. Low-fire glazes deliver bright reds, oranges, and yellows that burn out at higher temperatures.

Choose low-fire if vivid color matters more than durability—think decorative tiles, terra cotta, and hand-painted earthenware.

Mid-range clay (cone 5–6)

Stoneware fired at cone 5–6 reaches 2167°F to 2232°F. This range has become the studio standard for a reason. It produces strong, vitrified, food-safe ware without the fuel cost of high firing. Glaze options are wide. Durability is high.

Choose mid-range if you make functional pottery—mugs, bowls, dinnerware—and want strength without extreme heat.

High-fire clay (cone 9–10)

Porcelain and high-fire stoneware mature at 2300°F to 2381°F. The clay vitrifies fully, becoming dense and nearly nonporous. Glazes melt into deep, subtle surfaces prized for their richness. The trade-off is demand on your kiln and shelves.

Choose high-fire if you want maximum strength and the translucency porcelain can offer—and you have a kiln rated for the heat.

Always check the clay supplier’s listed cone range. It’s printed for a reason.

What is bisque firing and what temperature is it?

Bisque firing is the first firing. It turns fragile greenware into hard, porous ceramic.

Most potters bisque fire at cone 04–06, between 1828°F and 1945°F. The goal isn’t to mature the clay—it’s to drive off chemical water and organic material while leaving the piece porous enough to absorb glaze.

Slow is the rule here. Greenware holds water inside its walls. Heat it too fast and that water turns to steam, cracking or exploding the piece. A candling phase—holding the kiln near 200°F for an hour or two—lets moisture escape safely.

Once bisqued, the work becomes far easier to handle. It accepts glaze evenly. And it survives the bumps of a busy studio.

Why bisque fire at all?

You could glaze raw greenware in a single firing. Some potters do. But bisque firing gives you a sturdy, absorbent surface that grips glaze and resists breakage during decoration. For most makers, the extra firing pays for itself in fewer losses.

What temperature is glaze firing?

Glaze firing melts the glaze into a glass-like coat and brings the clay to maturity. The temperature depends entirely on your clay and glaze.

• Low-fire glaze: cone 06–04 (1828–1945°F)
• Mid-range glaze: cone 5–6 (2167–2232°F)
• High-fire glaze: cone 9–10 (2300–2381°F)

The rule is simple: match your glaze to your clay’s range. A cone 6 glaze on a cone 6 clay matures together. Put a low-fire glaze on high-fire clay and the glaze boils and burns away long before the clay is done.

Glaze firing usually runs hotter than bisque, so the kiln does more heat work. Many potters program a slow cool to encourage certain crystalline and matte effects. Cooling speed shapes the final surface as much as peak temperature does.

Choosing between low, mid, and high glaze firing

Pick your range based on the outcome you want:

• Want bold, saturated color? Low-fire gives you the brightest palette.
• Want durable, food-safe ware with broad glaze choice? Mid-range is the practical winner.
• Want depth, translucency, and maximum strength? High-fire delivers, if your equipment can handle it.

Decide the range before you buy clay. Everything downstream depends on it.

What advanced firing techniques should potters know?

Once you’ve mastered bisque and glaze firing, the work opens up. Several techniques push temperature and atmosphere in deliberate ways.

Reduction firing starves the kiln of oxygen during firing. Gas kilns do this well. The oxygen-hungry flame pulls oxygen from the clay and glaze, producing effects like celadon greens and copper reds that oxidation can’t match.

Oxidation firing keeps oxygen plentiful. This is how electric kilns fire by default. The results are clean, predictable, and bright—ideal for consistent production.

Raku firing pulls red-hot ware from the kiln at around cone 06 and places it into combustible material. The thermal shock and smoke create crackle glazes and metallic flashes. It’s fast, dramatic, and hard on the nerves.

Soaking holds the kiln at peak temperature for a set time. This evens out heat work across the load and helps glazes smooth and settle.

A few rules hold across all of them:

• Vent your kiln for safety and even results.
• Load shelves with space for heat to move.
• Log every firing—cone, schedule, results—so you can repeat success.

Tips for firing pottery successfully

Consistent firing comes down to habits, not luck.

• Always use witness cones. Place them where you can see them. They confirm what the pyrometer only estimates.
• Match clay and glaze to the same cone. This single check prevents most failures.
• Candle your greenware. A slow start prevents steam blowouts.
• Don’t crowd the kiln. Heat needs room to circulate evenly, top to bottom.
• Keep a firing log. Record every load. Your notes become your most reliable reference.

Master the cones, respect the clay’s range, and fire with patience. Strong, beautiful work follows.

Ready to fire? Start with a test load. Run witness cones, take notes, and build your own temperature reference from results you can trust.

Frequently asked questions

What happens if you fire clay at the wrong temperature?

Underfiring leaves clay weak and porous—it may leak, chip, or fail in use. Overfiring causes slumping, bloating, warping, or glaze running onto the shelf. Both ruin the piece. Always fire to your clay’s stated cone range.

Can you bisque fire and glaze fire at the same temperature?

Usually no. Bisque firing is intentionally cooler (cone 04–06) to keep the clay porous for glazing. Glaze firing is often hotter to mature the clay and melt the glaze. The exception is some low-fire work, where both firings sit close in range.

How long does a kiln firing take?

A typical bisque firing runs 8 to 12 hours, plus cooling time. A glaze firing takes a similar span, depending on the target cone and your kiln. Cooling can take just as long—never open a hot kiln, as thermal shock cracks ware.

What’s the difference between cone 6 and cone 06?

Cone 06 is a low-fire temperature, around 1828°F. Cone 6 is a mid-range temperature, around 2232°F—roughly 400°F hotter. The zero prefix marks the cooler scale. Confusing the two is a common and costly mistake.

Do you need a pyrometer if you use cones?

A pyrometer tracks temperature in real time and helps you control the firing schedule. Cones measure actual heat work and make the final call on whether your target is reached. Most serious potters use both together.

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Kiln Firing Temperatures: A Complete Guide for Potters
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Learn kiln firing temperatures by cone, from bisque to glaze. Get firing ranges for low, mid, and high-fire clay—plus tips for consistent results.