Glaze bubbles behaving badly! We see it in a melt fluidity test.

Wednesday 24th June 2015

These melted-down-ten-gram GBMF test balls of glaze demonstrate the different ways in which tiny bubbles disrupt transparent glazes. These bubbles are generated during firing as particles in the body and glaze decompose. This test is a good way to compare bubble sizes and populations, they are a product of melt viscosity and surface tension. The glaze on the top left is the clearest but has the largest bubbles, these are the type that are most likely to leave surface defects (you can see dimples). At the same time its lack of micro-bubbles will make it the most transparent in thinner layers. The one on the bottom right has so many tiny bubbles that it has turned white. Even though it is not flowing as much it will have less surface defects. The one on the top right has both large bubbles and tinier ones but no clouds of micro-bubbles.

Pages that reference this post in the Digitalfire Reference Database:

GBMF Glaze Melt Fluidity - Ball Test, Melt Fluidity, Glaze Bubbles, Clouding in Transparent Glazes

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