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mugs & thermal shock

updated mon 30 jun 97


Malone & Dean McRaine on sat 21 jun 97

Aloha ClayArteests:
My wife is an avid tea drinker so I have had first hand, long term testing
of my mugs daily for over 10 years. I've never done the freezer-to-boiling
test (yet). I use Dave's porcelain (Laguna) now and previously White Rose
porcelain from Clay Art in Tacoma. The only cracks I've gotten are rim
cracks going down the side of the mug with certain glazes that appear after
months or years. This suggests to me a glaze fit problem, glaze too big for
mug, compounded by heat expansion from hot water, i.e. the hot water causes
the glaze to expand enough to pull the clay at the rim apart. Any one had
this type of problem or have any ideas about it?