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Defect · Glaze firing
Blistering
Also called: boiling
Large glossy bubbles or craters in the glaze surface, often concentrated in one area.
- Appears at
- Glaze firing
- Severity
- Cosmetic
- How common
- uncommon
Causes
Most likely
- ·Overfiring -- glaze reached a boiling temperature
- ·High sulfur or carbon content in the clay body off-gassing under glaze
Prevention
- ·Fire within the glaze's rated cone range
- ·Extend bisque schedule to burn out volatiles
Can it be fixed?
- ·Sand or grind blisters if shallow; refire with a corrected schedule otherwise
Materials involved
Glaze materials whose chemistry sits behind this defect — each links to its reference page.
Related defects
Questions
- Why does blistering happen?
- Most often: Overfiring -- glaze reached a boiling temperature. Other causes: High sulfur or carbon content in the clay body off-gassing under glaze..
- Can blistering be fixed?
- Sometimes. Sand or grind blisters if shallow; refire with a corrected schedule otherwise.
- How do I prevent blistering?
- Fire within the glaze's rated cone range. Extend bisque schedule to burn out volatiles.
Sources. Compiled from Claybench's defect reference — the descriptions, causes and remedies that appear consistently across standard ceramics references and studio practice; no single source. It is the same reference the photo diagnosis tool reasons over. Where the Wikibooks Ceramicware Defects Handbook covers a defect it is linked above.
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