A mug cracks before your eyes because of glaze compression
Thursday 23rd August 2018
A highly vitreous, thin walled mug is glazed inside-only. The glaze has a thermal expansion that is too low and it is under compression, pressing outward. A tap with a spoon is enough to trigger a sudden crack. It opens under the pressure. Had it been glazed on the outside also it would likely survive, but this test still indicates that it would be better to raise the expansion a little.
Pages that reference this post in the Digitalfire Reference Database:
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.