Matching a glaze to your clay body
Why a glaze that's gorgeous on one clay crawls or crazes on another — and how to find recipes that actually fit yours.
A glaze isn't good or bad in the abstract — it's good or bad on a particular clay body, at a particular cone, in a particular kiln. The same recipe can be flawless on one stoneware and craze badly on another.
Fit is about expansion
Crazing (fine cracks) means the glaze shrinks more than the clay on cooling — its thermal expansion is too high. Shivering (flaking) is the opposite. Matching glaze and body expansion is the core of 'fit,' and it's why a recipe needs to be evaluated against your clay, not in isolation.
Match the cone first
Before anything else, the glaze's maturing range has to match your clay body's. A cone 10 glaze on a cone 6 body will be underfired and unsafe. This is the fastest filter and the one most often skipped when grabbing a recipe online.
Test tiles are non-negotiable
- ·Test every new glaze on your actual clay body before committing a batch.
- ·Fire the test in the kiln and schedule you'll really use.
- ·Check for crazing immediately and again after a day — some appears late.
Let Claybench do the math.
Plans that respect drying, firing, and your kiln — free to start.