An example of how much Gerstley Borate LOI can affect a glaze

Tuesday 20th February 2018

Fired at cone 6. The samples on the bottom tiles are from ten-gram balls that have melted down (in our GBMF test). These glazes have the same chemistry, but the one of the left sources its B2O3 from Gerstley insight-live.com/glossary/129">Borate (which has a high LOI). The one on the right gets it from a frit. Because the fritted version has less gases of decomposition to expel, the glass is much smoother. Curiously, the fritted version is flowing less and the red color has been lost. Why? This could be because the Al2O3, which stabilizes glazes against excessive fluidity, is being dissolved into the melt better and thus is more available for glass building.

Pages that reference this post in the Digitalfire Reference Library:

Gerstley Borate, This is how bad Gerstley Borate glazes can blister, LOI, Limit Recipe

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.