Glaze Thermal Expansion (COE) Calculator
Glaze
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Glaze Thermal Expansion (COE) Calculator
Calculate the coefficient of thermal expansion (COE) of a glaze from its oxide composition.
Reviewed by ClayCalc Editorial · Updated
Enter oxide mole fractions from your glaze UMF analysis. Leave unused oxides blank.
Results
Enter your measurements above and click Calculate.
Appen Coefficients & Glaze Fit
This calculator uses Appen oxide coefficients (×10⁻⁷/°C) to estimate Coefficient of Thermal Expansion (COE). The COE is the weighted sum of each oxide's contribution normalized to total mole fractions.
Glaze fit depends on the difference between glaze and clay body COE. The glaze should contract slightly less than the body on cooling — putting it in mild compression — which produces a harder, more durable surface and prevents crazing.
| Result | Cause | Fix |
|---|---|---|
| Crazing | Glaze COE > Clay COE | Lower glaze COE (add Al₂O₃, reduce Na₂O) |
| Shivering | Glaze COE << Clay COE | Raise glaze COE (add Na₂O or K₂O feldspar) |
Method & review note
About this calculation
Performs recipe and slurry arithmetic. A calculated percentage or expansion estimate cannot establish glaze durability, fit, toxicity, or food-contact suitability.
Reference: Digitalfire — Ceramic Glaze. See the editorial methodology for testing, precision and corrections.
Input handling: Values are sent to the ClayCalc server for this request and are not written to the application database.