Glaze melt fluidity comparison: Same chemistries, different recipes

Friday 28th October 2016

At low temperatures, potters want transparents with good clarity to support brilliant colors. Especially on terra cotta bodies. A insight-live.com/glossary/112">melt flow test like this enables a comparison one cannot do on using glazed test tiles.

These are two low temperature glazes I use at cone 03, G2931F and G2931K. They have the same chemistry. But F gets its boron from Ulexite, a material with a high LOI (notice how the escaping gases have disrupted the downward flow). The frit-sourced boron version on the right flows cleanly and contains almost no obvious bubbles.

So obviously, one would use the K, right? Not exactly. I used the K version successfully on many pieces. In a thin layer, the ulexite seems to act as its own fining agent, like Gerstley Borate, and the bubbles do merge clear well enough.

Pages that reference this post in the Digitalfire Reference Library:

GLFL Glaze Melt Flow - Runway Test, Two glazes of the same chemistry: But supplied by different sets of materials, LOI, Frit, Glaze Bubbles

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.