By the Home Kiln Hub UK – The Definitive Guide to Ceramic Kilns for British Potters Team · Updated May 2026 · Independent, reader-supported

Pottery Kiln Temperature Guide UK – Cone Chart, Clay Bodies & Glaze Ranges

Getting kiln temperature right is one of the most critical decisions in ceramics. Fire too cool and your clay won't mature properly—glazes stay raw, pots remain porous. Fire too hot and glazes melt into blobs, clay warps, and you risk kiln damage. This guide cuts through the confusion and shows you exactly what temperature ranges work for different clay bodies and glazes.

Understanding the Cone System

Cones are the standard reference in ceramic firing across the UK and beyond. They're small ceramic pyramids that bend at specific temperatures, giving you a reliable visual indicator of heat-work inside your kiln—not just the dial reading.

The cone system accounts for two things: temperature and time. A kiln at 1200°C for 5 minutes fires completely differently to 1200°C held for 2 hours. Cones track the cumulative effect. This is why they're more dependable than thermocouples alone.

The most commonly used systems in the UK are:

• Orton cones (the standard): numbered 022 to 15, from around 600°C to 1350°C
• Seger cones: older system, still referenced in some European kilns, slightly different temperature points

For home potters, you'll typically work with cones 6 to 10 (stoneware) or cones 04 to 6 (earthenware and mid-fire work).

Clay Body Temperature Ranges

Your clay body has a maximum firing temperature it can handle before it begins to over-fire—glazes turn glassy, colours shift, and the pot becomes brittle instead of durable.

Earthenware: Fires in the low range—cone 04 to 02 (1040–1120°C). Earthenware is porous when fired correctly; that's normal. It's lighter, warmer to handle, and absorbs water easily, making it ideal for decorative pieces and plant pots. Over-firing earthenware makes it dense and changes colour dramatically.

Stoneware: The workhorse of British pottery. Fires between cone 6 and 10 (1220–1300°C). Stoneware matures fully at these temperatures, becoming non-porous and durable enough for tableware and functional work. Most home kiln setups are calibrated around cone 6–8.

Porcelain: Requires higher temperatures, typically cone 8 to 13 (1260–1350°C). Porcelain is unforgiving—it's harder to throw, more prone to warping, and the narrow window between perfect and over-fired is real. Many UK potters find the investment in time outweighs the commercial value, though it's stunning when done well.

Professional potters often work at the top end of their clay's range to maximise strength and reduce water absorption. A cone 6 stoneware pushed to full maturity is nearly as durable as cone 10.

Glaze Firing Temperatures

Glazes are formulated for specific cone ranges. A glaze listed as "cone 6" will melt and mature properly at cone 6—usually sitting somewhere between cone 5 and 7 in practice. Fire it at cone 10 and it runs off the pot or vitrifies into a glass-like blob.

Many glaze recipes specify a range—for example, "cone 6–8"—which means the glaze works acceptably across that window, though the colour and texture may shift slightly at the extremes.

Common UK cone ranges:

• Cone 04–02 (low-fire): bright colours, glossy surfaces, faster firing. Popular for decorative earthenware. Many commercial glazes are formulated here.
• Cone 6 (mid-fire): the sweet spot for many home and small studio potters. Good glaze range available, relatively fast firing, lower kiln wear.
• Cone 8–10 (high-fire): deeper, more sophisticated colours, harder and more durable finishes. Classic stoneware glazes live here—the matte blacks, celadons, and ash glazes that feel premium.

Misfiring happens when you fire a cone 6 glaze in a cone 10 kiln. The glaze melts excessively, pooling at the base and potentially bonding the pot to the shelf. Similarly, firing cone 10 stoneware at cone 6 leaves the clay underfired and porous.

Bisque vs Glaze Firing

Bisque (the first firing) is usually fast and fairly forgiving, typically cone 04 to 06 (1040–1080°C). Speed doesn't matter; you're driving off all remaining moisture and achieving enough hardness that glazes don't dust off during handling.

Glaze firing is slower and more controlled. A slow rise through 1000–1100°C allows moisture in the glaze to escape without blistering. Soaking at the top temperature—holding the kiln steady for 15–30 minutes—ensures even glaze melt and colour development.

Temperature Measurement in Practice

A digital controller and thermocouple read kiln chamber temperature, which is helpful for consistency and speed. However, the shelf where your pots sit may experience a different temperature—especially in uneven kilns. Placing cones inside the kiln (not touching shelves) remains the most reliable way to know whether your work has actually reached the intended heat-work.

Many UK potters keep written firing records: date, cone placement, visual observations at temperature, and how the finished work looked. After two or three firings, you'll spot patterns in your kiln's hot and cool spots.

Common Firing Problems

Underfiring: Glazes remain chalky or unmelted; clay stays porous. Usually caused by opening the kiln too soon to check progress or kiln thermostats drifting downward over time.

Overfiring: Glazes run, colours darken (sometimes beautifully, sometimes not), clay warps. Happens when cones are misplaced or kiln thermostats have drifted upward.

Uneven firing: One shelf matures while another underfires. Check kiln shelves are level and unobstructed inside. Many potters place cones at different heights to diagnose this.

Fire with intent. Know your kiln's personality, use cones every time, and keep notes. The difference between a mediocre result and exceptional work often comes down to understanding these temperature windows properly.