skills/pottery-mentor/references/kiln_cones_and_firing.md

# Kilns, Cones, and Firing

## Heatwork

Pyrometric cones respond to heatwork: temperature plus time/rate.

A cone number is not one universal exact temperature.

Equivalent temperature varies with heating rate and firing profile.

When exact equivalencies matter, use the current Orton cone chart or manufacturer documentation for the specific cone type/rate.

## Witness cones

Use witness cones to verify what the ware experienced rather than trusting controller setpoint alone.

A useful three-cone pack can include:
- guide cone;
- target/firing cone;
- guard cone.

For kiln-uniformity troubleshooting, place cone packs at representative top/middle/bottom and other relevant positions.

Record fired cone positions.

## Electronic controllers

Controllers and thermocouples are useful but are not a substitute for verifying heatwork when process control matters.

Thermocouples age and kiln behavior changes.

## Firing questions

Collect:
- kiln brand/model;
- controller type;
- electrical/gas;
- bisque or glaze;
- clay/glaze rated cone;
- target cone;
- firing program;
- holds;
- cooling;
- witness-cone result;
- load density;
- kiln position differences.

## Thick / sculptural ware

Large or thick work may need specialized drying and firing schedules.

Do not prescribe a universal slow schedule without knowing:
- material;
- thickness;
- construction;
- dryness;
- kiln;
- manufacturer limits.

## Holds / soaks

A hold adds heatwork.

Do not add long holds to a cone schedule without considering how that changes maturation and defects.

## Cooling

Cooling can materially affect:
- glaze crystal development;
- matte/gloss character;
- some color responses;
- thermal stress.

Do not use slow cooling as a universal cure for glaze-fit problems.

## Logs

Record:
- date;
- kiln;
- load;
- program;
- target;
- hold/cool;
- cone packs;
- anomalies;
- result.

A firing log turns future troubleshooting from guesswork into comparison.