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Understanding Pottery Kiln Temperatures
Getting your firing temperatures right is the single biggest factor in whether your pottery survives the kiln — and whether your glazes look the way you intended. This guide explains bisque and glaze firing temperatures for UK potters, how pyrometric cones work, a full Orton cone chart, a typical firing schedule, and how to avoid the most common firing faults. Whether you are choosing your first pottery kiln or fine-tuning an existing one, understanding heatwork is the key to consistent results.
What ‘Firing’ Really Means: Heatwork, Not Just Temperature
Firing is the controlled heating of clay until it changes permanently into a hard, durable ceramic. The crucial idea every potter needs is heatwork — the combined effect of how hot the kiln gets and how long it stays there. Two firings can reach the same peak temperature yet produce very different results, because one was held longer than the other. This is why potters measure firings in cones rather than degrees alone.
The Two Key Firings: Bisque and Glaze
Bisque Firing
The bisque (or ‘biscuit’) firing is the first firing. It converts fragile dried clay into hard, porous ceramic that is strong enough to handle and absorbent enough to take glaze. Most potters bisque fire to around 1,000°C (Orton cone 06–04). The early stages must be slow: free water leaves below 100°C, and chemically combined water leaves between roughly 300°C and 600°C. Rushing this stage is the most common cause of pots exploding in the kiln.
Glaze Firing
The glaze firing melts the glaze onto the bisque ware and brings the clay to maturity. The right temperature depends entirely on your clay body: earthenware around 1,100–1,150°C, stoneware around 1,220–1,280°C, and porcelain around 1,260–1,300°C. Always match the firing to the range printed on your clay and glaze — firing stoneware glaze on an earthenware body, or vice versa, is a frequent and avoidable mistake. New to glazing? See our beginner’s guide to glazing pottery.
Pottery Firing Temperatures at a Glance
| Clay / stage | Typical temperature | Orton cone |
|---|---|---|
| Bisque (most clay bodies) | ~1,000°C | 06–04 |
| Earthenware glaze | 1,100–1,150°C | 03–1 |
| Stoneware glaze | 1,220–1,280°C | 6–10 |
| Porcelain glaze | 1,260–1,300°C | 8–10 |
| Raku | ~1,000°C | 06–06a |
Understanding Pyrometric Cones
A pyrometric cone is a small pyramid made from carefully blended ceramic materials that bends at a known amount of heatwork. Potters stand cones on a kiln shelf (or use them in a kiln-sitter) so they can see exactly how far the firing has progressed. A digital controller reads temperature from a thermocouple, but a cone reacts to temperature and time together — so cones remain the most reliable way to confirm a firing. As a rule of thumb, the higher the cone number in the high-fire range, the more heatwork; in the low-fire ‘0’ series it is the reverse — 022 is the coolest and 01 the hottest.
The chart below lists Orton cones against the temperature at which they deform, at two common ramp rates. Note how the same cone bends at a slightly higher temperature when the kiln climbs faster — further proof that time matters as much as temperature.
| Orton cone | At 60°C/hour | At 150°C/hour |
|---|---|---|
| 019 | 676°C | 693°C |
| 018 | 712°C | 732°C |
| 017 | 736°C | 761°C |
| 016 | 769°C | 794°C |
| 015 | 788°C | 816°C |
| 014 | 807°C | 836°C |
| 013 | 837°C | 859°C |
| 012 | 858°C | 880°C |
| 011 | 873°C | 892°C |
| 010 | 898°C | 913°C |
| 09 | 917°C | 928°C |
| 08 | 942°C | 954°C |
| 07 | 973°C | 985°C |
| 06 | 995°C | 1011°C |
| 05 | 1030°C | 1046°C |
| 04 | 1060°C | 1070°C |
| 03 | 1086°C | 1101°C |
| 02 | 1101°C | 1120°C |
| 01 | 1117°C | 1137°C |
| 1 | 1136°C | 1154°C |
| 2 | 1142°C | 1162°C |
| 3 | 1152°C | 1168°C |
| 4 | 1160°C | 1181°C |
| 5 | 1184°C | 1205°C |
| 6 | 1220°C | 1241°C |
| 7 | 1237°C | 1255°C |
| 8 | 1247°C | 1269°C |
| 9 | 1257°C | 1278°C |
| 10 | 1282°C | 1303°C |
| 11 | 1293°C | 1312°C |
| 12 | 1304°C | 1324°C |
A Typical Firing Schedule
A firing is a sequence of ramps (controlled rates of temperature rise), optional soaks (holds at a set temperature) and a controlled cool. A typical bisque might climb gently at 60–100°C per hour to about 600°C, then faster to the target of around 1,000°C, with a short soak to even out the heat. A stoneware glaze firing often ramps faster to peak, soaks for 10–20 minutes, then cools in a controlled way to help glazes develop. A programmable controller makes all of this repeatable — which is why we recommend one for anyone firing regularly.
Common Firing Problems and How to Avoid Them
Pots exploding: almost always trapped moisture or air, or too fast an early ramp — dry ware thoroughly and candle (hold low) at the start. Underfiring: glazes look dry or rough and clay stays porous — the kiln didn’t reach the cone; check your thermocouple and schedule. Overfiring: glazes run, clay bloats or slumps — the firing went past the cone. Dunting: cracks from cooling too quickly — let the kiln cool slowly and don’t open it hot. Using cones alongside your controller is the simplest way to catch these before they ruin a kiln load.
Choosing a Kiln for the Temperatures You Need
Different work needs different kilns. Beginners often start with a small pottery kiln such as the CU2 Home Pottery Kiln, stepping up to the CU4 Home Pottery Kiln for larger pieces. If you only have a standard domestic socket, our 13amp pottery kilns reach full stoneware temperatures on a normal plug. For studios, top-loading and front-loading kilns offer more capacity, and our large 100L+ kilns — such as the Falcon 250L Front-Load Pottery Kiln — cover high-temperature, high-volume firing. All of our electric pottery kilns are built to hold the cone you need, firing after firing.
KilnCare
Built in Stoke-on-Trent, KilnCare kilns are a UK-made, controller-equipped choice trusted for reliable, repeatable firings.
Kilns and Furnaces
Kilns and Furnaces has decades of pedigree building durable, precise pottery kilns for hobbyists and professionals alike.
Master the relationship between temperature, time and cones, and firing stops being a gamble and becomes the most rewarding part of pottery. If you need help matching a kiln to the temperatures you fire to, the team at Kiln Crafts is always happy to advise.
Frequently Asked Questions
What temperature is a bisque firing?
Most potters bisque fire to around 1,000°C (Orton cone 06–04). This drives off the chemically combined water and hardens the clay into ‘biscuit’ ware, while leaving it porous enough to absorb glaze evenly. Some studios bisque a little cooler (cone 08, ~950°C) for very porous ware, or hotter (cone 04, ~1,060°C) for a denser bisque.
What temperature is a glaze firing?
It depends on the clay body. Earthenware is glaze fired at roughly 1,100–1,150°C (cone 03–1), stoneware at 1,220–1,280°C (cone 6–10, most commonly around 1,250°C) and porcelain at 1,260–1,300°C (cone 8–10). Always fire to the range stated on your clay and glaze.
What is a pyrometric cone?
A pyrometric cone is a small pyramid of ceramic material formulated to soften and bend at a specific amount of heatwork — the combined effect of temperature and time. Because a cone reacts to both, it tells you the true firing your ware received, which a thermocouple reading temperature alone cannot.
Why does heatwork matter more than temperature?
Clay and glaze mature through a combination of how hot the kiln gets and how long it is held there. The same maturity can be reached at a lower temperature held longer, or a higher temperature reached quickly. Cones measure that combined effect, which is why two firings to the same peak temperature can give different results.
How long does a pottery firing take?
A bisque firing typically runs 8–12 hours, and a stoneware glaze firing around 10–14 hours. You then need to let the kiln cool — usually several hours, and ideally until it is below 100°C — before opening, to avoid thermal shock cracking your work.
Do I need a kiln with a controller?
A programmable controller lets you set ramp rates, holds (soaks) and controlled cooling automatically, giving far more consistent results than firing by eye. Most modern kilns Kiln Crafts supplies include a digital controller as standard.