Refiring a terra cotta mug that had already bubbled only made blistering worse

Plus the glaze ran even more. The main problem was that the original firing was taken too high, about cone 02 (seven hour schedule). This body nears zero porosity there and is beginning to decompose. That generates gases. The second firing was taken to cone 03 in four hours. But the glaze just percolated more. However freshly glazed bisque ware in that same firing came out perfect. Lessons were learned. Fire faster. Keep it cone 03 or lower. Do not put the glaze on too thick. Use self-supporting cones to verify the electronic controller, they are much more accurate than regular cones.

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Glossary	Refiring Ceramics Refiring pottery and porcelain comes with many issues that can ruin ware, knowing about these will help you do it successfully.
Glossary	Terra Cotta A type of red firing pottery. Terra cotta clay is available almost everywhere, it is fired at low temperatures. But quality is deceptively difficult to achieve.
Troubles	Glaze Blisters Questions and suggestions to help you reason out the real cause of ceramic glaze blistering and bubbling problems and work out a solution

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