Original glaze with Gerstley Borate vs. fixed version with frit

Tuesday 12th September 2017

These pieces are the same body and fired at the same temperature. The original glaze was found on the internet, and is popular. Materials within it are "farting" as the glaze is melting (they have a high LOI and the calculated LOI of the glaze as a whole is 15%). Unless it is applied very thinly this is the fired result (at cone 03): tons of micro-bubbles. And it is crazing. Using my account at insight-live.com I was able to source the B2O3 and MgO from a frit (actually two frits) and reduce the thermal expansion at the same time. As you can see, the product is a dazzling ultra clear (thick or thin) that fits perfect (it survives a 300F-to-ice-water IWCT test).

Pages that reference this post in the Digitalfire Reference Database:

Gerstley Borate, LOI

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.