What a kiln schedule actually is

A kiln schedule is simply a set of instructions you give your kiln: how quickly it should heat up, how long it should hold at a given temperature, and how fast it should cool. On a small electric kiln with a digital controller, that means a handful of segments typed into a keypad — a target temperature, a ramp rate in degrees per hour, and a soak time. Nothing more mystical than that.

Where beginners come unstuck is assuming the peak temperature is the only thing that matters. It isn't. Clay and glaze respond to heatwork — the combined effect of the temperature reached and the time spent getting there and sitting there. Reach 1240°C in four hours and your glaze may look very different from the same glaze taken to 1240°C over eight. This is why two potters using the same clay, the same glaze and a similar kiln can end up with completely different results.

The two numbers that do most of the work: ramp and soak

Ramp is the rate of climb, usually written as degrees Celsius per hour. Soak (sometimes called dwell) is the hold at the top temperature before the kiln switches off.

As a rough guide for a small electric kiln:

• A slow ramp — 60 to 100°C per hour — belongs in the early stages, especially below 600°C.
• A moderate ramp — 120 to 150°C per hour — is fine through the middle of the firing.
• A gentle final ramp — 80 to 100°C per hour — gives glazes time to melt smoothly.
• A soak of 10 to 20 minutes at the top temperature evens out hot and cold spots in the chamber.

Cooling matters just as much. Most small electric kilns are best left to cool naturally with the lid and bungs closed. Opening up early is the fastest route to dunting — the crack that appears as your pot contracts faster than it can cope with.

A reliable bisque schedule for a small electric kiln

Bisque firing turns raw, fragile greenware into durable, absorbent pottery ready for glazing. The golden rule is slow at the start.

• Ramp 60–100°C per hour to 120°C. If your work is thick, or you fire in a cold or damp workshop, hold here for 30 minutes. This is the water-smoking stage.
• Ramp 100–150°C per hour to 600°C. Residual moisture and organic matter burn away here.
• Ramp 150°C per hour to 1000°C — or 1000–1060°C for earthenware bodies. Always check the recommendation for your specific clay.
• Soak for 10–15 minutes, then switch off and let the kiln cool completely.

Don't be tempted to skip that early slow section. Trapped moisture turns to steam, and steam needs somewhere to go. A pot taken up too fast will make that decision for you, usually with an audible bang.

A reliable glaze schedule for a small electric kiln

Glaze firing takes your bisqued pot to maturity. Here's a straightforward stoneware schedule for a body that matures around 1240–1260°C.

• Ramp 100°C per hour to 600°C.
• Ramp 150°C per hour to 1100°C.
• Ramp 80–100°C per hour to your top temperature — say 1240°C or 1250°C.
• Soak for 15–20 minutes.

That final slow ramp plus soak is what makes glazes look settled rather than scabby. It gives the melt time to flow, heal pinholes and smooth itself out. If your glazes are coming out dry or underfired, extend the soak before you reach for a higher top temperature — a longer hold at the same peak often does the job more kindly, and with less risk to the clay body.

Common beginner mistakes and the simple fixes

• Firing too fast below 600°C. Slow it down. Patience here saves pots.
• Packing the kiln too tightly. Leave a finger's width between pieces so heat can circulate.
• Mixing clay bodies in one firing. Different clays mature at different temperatures. Keep them separate, or accept the risk.
• Opening the lid to "check". Wait until the kiln reads below 100°C. Warm pots and cold air don't mix.
• Trusting one thermocouple absolutely. Your controller reads the air near the probe, not every corner of the chamber. Cones placed around the kiln tell the real story.

Keep a firing log, and change one thing at a time

Every kiln has its own personality — a hot front corner, a cool bottom shelf, a tendency to overshoot on the way up. The only way to learn yours is to write things down.

For each firing, note the date, clay body, glazes used, how the kiln was loaded, the schedule you programmed, and what the cones told you. Add a line about the results once you've unpacked. After half a dozen firings you'll spot patterns you'd never remember otherwise.

Then change just one variable per firing. Raise the soak by ten minutes. Slow the final ramp. Move a piece from the bottom shelf to the middle. Small, deliberate adjustments build real understanding far quicker than chasing someone else's perfect schedule. Your kiln, your clay, your workshop — the schedule that works is the one you've tuned yourself.