The difference in fired character between kaolin and ball clay is not what you might expect

Wednesday 27th July 2016

These test bars are fired at cone 10R. The top one is EP Kaolin, the bottom one is Old Hickory M23 Ball Clay (these materials are typical of their respective types). It is interesting that although the kaolin has a much larger ultimate particle size it is shrinking alot more (23% vs. 14%). This is counterintuitive to what should be happening. And another thing: the kaolin has a porosity of 0.5% and the ball clay is 1.5%. This is also counterintuitive. The kaolin should be more refractory since it contains less fluxing oxide impurities. In fact, both should theoretically be a lot more refractory than they actually are.

Pages that reference this post in the Digitalfire Reference Database:

Kaolin, Ball Clay

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