Bloating. These teapots have been refired to cone 6. This is just a standard porcelain body (feldspar, kaolin, silica, ball clay) that vitrifies fully at about cone 7. The second firing is obviously vitrifying to an equivalent of more than that.
Glossary |
Vitrification
The term vitrified refers to the fired state of a piece of porcelain or stoneware. Vitrified ware has been fired high enough to make it very strong, hard and dense. |
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Glossary |
Refiring Ceramics
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Troubles |
Body Bloating
Bloating in clay bodies occurs when the firing goes high enough to seal the surface and prevent the passage of gases releasing inside. |