Original glaze with Gerstley Borate vs. improved version with frit

Tuesday 12th September 2017

These pieces are fired at the same temperature. The glaze on the left is a popular recipe found online, Worthington Clear (our insight-live.com/glossary/302">code number G2931). The Gerstley Borate in it is "farting" as the glaze is melting (the calculated LOI of the glaze as a whole is 15% mainly from that one material). Unless applied very thinly tons of micro-bubbles appear (this example is fired to cone 03). And strange, it is crazing badly also despite the low calculated thermal expansion. Using my account at insight-live.com I was able to source the B2O3 and MgO from a frit (actually two frits) to create the G2931K recipe. Although the thermal expansion calculates higher it is strangely fitting better (albeit not firing as white). As you can see, the new fritted glaze is very glassy and clear (thick or thin).

Pages that reference this post in the Digitalfire Reference Library:

Gerstley Borate, Frit made this Gerstley Borate glaze much better , Gerstley Borate is passing on to a better place. With a 300% price hike., This is how bad Gerstley Borate glazes can blister, Remove Gerstley Borate and Improve a Popular Cone 6 Clear Glaze, Getting Frustrated With a 55% Gerstley Borate Glaze, Use Insight-live to substitute materials in a recipe, LOI, Glaze Gelling

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.