Tom Beyer on thu 10 apr 97
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A friend at my guild has a mysterious problem that I was hoping I could get =
some
help on. She throws very thin porcelain bowls and usually dips them in a =
single
glaze. In the last kiln load she had 4 different bowls come out with =
blisters
right in the center of the bottom of the bowl. These bowls each had a =
different
glaze on them (ranging from mat to shiney) and were in different parts of =
the
kiln. The firing was cone 6 oxidation.
The glaze covering looked fairly uniform and didn't seem too thick. In =
addition
we couldn't see any difference between the bowls that blistered and those =
that
didn't.
Oh, and one other thing. Usually she glazes the underside-inside of the =
foot
but on this set of bowls she left it bare (for both those that blistered =
and
those that didn't).
Does anybody have any idea what could be going wrong? Is glaze blistering =
worse
with thinner clay? Is the fact that the clay was glazed on one side only a
factor? Any and all ideas would be appreciated=21
TIA,
Tom, in MI where a week from Jan. seems to have inserted itself into April.
tbeyer=40mediastation.com
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