Turning delayed crazing into immediate crazing

Wednesday 4th February 2015

This is a cone 04 clay (Plainsman Buffstone) with a transparent glaze (G1916Q which is 65% Frit 3195, 20% Frit 3110, 15% EPK). On coming out of the kiln, the glaze looked fine, crystal clear, no crazing. However when heated to 300F and then immersed into ice water this happens (IWCT test)! At lower temperatures, where bodies are porous, water immediately penetrates the cracks and begins to waterlog the body below. Fixing the problem was easy: Substitute the low expansion Frit 3249 for the Frit 3110.

Pages that reference this post in the Digitalfire Reference Library:

BWIW Boiling Water:Ice Water Glaze Fit Test, IWCT 300F:Ice Water Crazing Test, G1916Q - Low Fire Frit 3195 Glossy Transparent, Crazing

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.