Vince Pitelka on sat 19 mar 05
Mike -
I am perplexed as to why those glazed pieces would crack, especially in a
slow cool-down, unless cooling was quick at the end. If there were
stresses in the piece because of drying proceedures or whatever, that could
have increased the liklihood of them letting go in the latter stages of
cooling. But Soldate should not do that. The only other possible reason I
can think of is a violent disagreement between the interior glaze and the
claybody. Is there any chance that the interior glaze pooled in the bottom
of the vase? If so, that could be the cause. I have seen pieces crack in
the fashion you describe just because of a thick interior glaze that shrinks
less than the claybody. One other possibility - if you glazed the inside
with a shino, the soda ash can cause the clay to over-vitrify, which will
increase the chance of cracking due to glaze-clay disagreement.
Hope this helps.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
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