← All defects
Defect · Glaze firing
Glaze running
Also called: glaze drips, glaze shelf damage
Glaze flows off the piece onto the kiln shelf or forms thick drips on the bottom edge.
- Appears at
- Glaze firing
- Severity
- Affects function
- How common
- Common
Causes
Most likely
- ·Glaze applied too thickly, especially near the foot
- ·Glaze overfired past its maturation point
- ·Glaze recipe has too much flux for its firing cone
Prevention
- ·Keep the bottom ~1/4" of the piece free of glaze
- ·Use kiln wash on shelves
- ·Fire at the glaze's rated cone, not higher
Can it be fixed?
- ·Grind drips off the foot with a diamond pad once cool
Materials involved
Glaze materials whose chemistry sits behind this defect — each links to its reference page.
Related defects
Questions
- Why does glaze running happen?
- Most often: Glaze applied too thickly, especially near the foot. Other causes: Glaze overfired past its maturation point. Glaze recipe has too much flux for its firing cone..
- Can glaze running be fixed?
- Sometimes. Grind drips off the foot with a diamond pad once cool.
- How do I prevent glaze running?
- Keep the bottom ~1/4" of the piece free of glaze. Use kiln wash on shelves. Fire at the glaze's rated cone, not higher.
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.
Not sure which defect you're looking at?
Claybench can read a photo of the pot against this same reference and rank the likely causes for your clay, glaze and firing.