May 2026: We are continuing a major code rewrite. Please contact us if you find issues. Thank you.
It was spray applied on the dried bowl (no bisque fire) an was too thick (not to mention under fired). But the main problem was a glaze recipe having too high a clay content. If a glaze has more than about 25% clay, consider a mix of the raw clay and calcined. For example, you can buy calcined kaolin to mix with raw kaolin. Or you can calcine the clay in bowls in your kiln by firing it to about 1200F.
| Glossary |
Calcination
Calcining is simply firing a ceramic material to create a powder of new physical properties. Often it is done to kill the plasticity or burn away the hydrates, carbonates, sulfates of a clay or refractory material. |
| Materials |
Calcined Kaolin
This is kaolin powder that has been fired in a furnace to remove the 12% crystal water and render it non-plastic. |
| Troubles |
Crawling
Ask yourself the right questions to figure out the real cause of a glaze crawling issue. Deal with the problem, not the symptoms. |
![]() PayPal | No tracking, No ads, No paywall, No transient content! Just organized, concise information constantly updated and improved. Was this helpful? Consider supporting me. |
Buy me a coffee and we can talk