Pinholes and blisters are the two defects most often confused with each other, and telling them apart is the first step to fixing either one. Both leave a disrupted glaze surface, but they come from different problems and call for different fixes.
Pinholes are tiny holes, about the size of a pinhead, that go all the way down through the glaze to the clay body. Blisters are larger craters, up to about an eighth of an inch, that look like popped bubbles. A useful test: if thickening the glaze reduces the count but reveals dome-shaped healed craters, you were actually looking at blisters, not pinholes.
| Fix | Why it works |
|---|---|
| Bisque hotter than you glaze fire | Burns off organics before the glaze seals the surface |
| Add a 15–30 min soak at peak | Gives the glaze time to heal over escaping gas |
| Slow the final cool | Lets bubbles settle out instead of freezing in place |
| Back off peak temp (blisters) | Blisters usually mean the glaze was pushed too hot |
| Apply an even, moderate coat | Very thick glaze traps gas; very thin exposes the body |
For most hobby potters, the fix that solves the most pinholes is a proper bisque plus a short hold at peak temperature during the glaze firing. That soak is the difference between a glaze that heals over and one that freezes mid-outgas. A programmable controller makes adding a hold trivial, which is one more reason a manual kiln-sitter setup can hold you back on tricky glazes.
A controller that can add soaks and controlled cooling solves a surprising number of surface defects. Call or text me, Spencer, at (801) 839-5882 and I'll help you match a kiln and controller to the work you're firing.
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