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Example of a glaze (G1916J) shivering on the rim of a mug. But the situation is not as it might appear. This is a low quartz cone 03 vitreous red body having a lower-than-typical thermal expansion. The white slip (or engobe) has a moderate amount of quartz and is thus put under some compression by the body. But the compression is not enough to shiver off (e.g. at the rim) when by itself. However the covering glaze has an even lower expansion exerting added compression on the slip. This causes a failure at the slip-body interface.
Glossary |
Quartz Inversion
In ceramics, this refers to the sudden volume change in crystalline quartz particles experience as they pass up and down a temperature window centering on 573C. |
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Glossary |
Glaze fit
In ceramics, glaze fit refers to the thermal expansion compatibility between glaze and clay body. When the fit is not good the glaze forms a crack pattern or flakes off on contours. |
Glossary |
Glaze shivering
Shivering is a ceramic glaze defect that results in tiny flakes of glaze peeling off edges of ceramic ware. It happens because the thermal expansion of the body is too much higher than the glaze. |
Glossary |
Engobe
Engobes are high-clay slurries that are applied to leather hard or dry ceramics. They fire opaque and are used for functional or decorative purposes. They are formulated to match the firing shrinkage and thermal expansion of the body. |
Troubles |
Glaze Shivering
Ask the right questions to analyse the real cause of glaze shivering. Do not just treat the symptoms, the real cause is thermal expansion mismatch with the body. |
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