Why is the clay blistering on this figurine?

Tuesday 19th May 2015

This is an admirable first effort by a budding artist. They used a built-in cone 6 program on an insight-live.com/glossary/23">electronic controller equipped electric kiln. But it is overfired. How do we know that? To the right are fired test bars of this clay, they go from cone 4 (top) to cone 8 (bottom). The data sheet of this clay warns not to fire over cone 6. Why? Notice the cone 7 bar has turned to a solid grey and started blistering and the cone 8 one is blistering much more. That cone 8 bar is the same color as the figurine (although the colors do not match on the photo). The solution: Calibrate the kiln sitter by using a self-supporting cone.

Pages that reference this post in the Digitalfire Reference Library:

Manually programming a Bartlett V6-CF hobby kiln controller, Kiln Controller, Bloating, Over Firing of Ceramic Glazes and Bodies

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.