Secret #2 of crystalline glazes: The chemistry

Wednesday 21st April 2010

Close-up of a insight-live.com/glossary/44">crystalline glaze. These crystals grow because both the glaze chemistry and the firing schedule have been tuned specifically to make that happen. The melt must be very fluid, so they contain lots of flux and very little Al2O3 (since alumina stiffens the melt and inhibits crystal growth). They also contain lots of ZnO and enough SiO2 to form zinc-silicate crystals. Since clays and feldspars contribute alumina, crystalline recipes use very little of either, relying on frits and other low-alumina materials.

This is very much DIY territory. You test, adjust, document and repeat. The best crystalline glaze people often do hundreds of firings to dial in a recipe and firing schedule.

Pages that reference this post in the Digitalfire Reference Library:

Zinc Oxide, Crystalline glazed vase by Rod and Denyse Simair, Secret #1 of crystalline glazes: The firing schedule, Secret #3 of crystalline glazes: They run. A glaze catcher is needed., Crystalline glazes, Crystallization, Glaze Chemistry, Metal Oxides

This post is one of thousands found in the Digitalfire Reference Database. Most are part of a timeline maintained by Tony Hansen. You can search that timeline on the home page of digitalfire.com.