Crazing kills ware strength: These two commercial brushing glazes prove it.

Tuesday 9th October 2018

These are Amaco bottled glazes, a transparent and a decorative on a insight-live.com/glossary/71">porcelain at cone 6. The glaze fit is poor, severely weakening the piece. I tapped this lightly with a spoon about 2 cm below the rim. It sounded like I was hitting a wet sack of rocks! And the handle fell off! Another few taps and the piece broke like auto-glass. This type of functional ware is entirely unacceptable. The IWCT test, which anyone can do, can help assess the risk.

If you buy commercial bottled brushing glazes then there is nothing you can do to adjust the recipe. When they fit a clay body (without crazing) it is just by accident (since the clay body and glaze manufacturer do not cooperate to ensure fit). Unfortunately, it is common for them to craze.

Pages that reference this post in the Digitalfire Reference Library:

Making your own glazes, Glaze 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.