Andie Carpenter on sun 1 apr 01
Help!
I have 50 porcelain cups made for a show next week, and am doing the
final glazing.
The outside is a colored crackle, which I have used many times on this
clay, but never in combination with the clear I'm using on the inside. I
never use it on the inside of anything, and have never had any problems
with it affecting the various interior glazes I've tried with it, or any
problem with overlapping it with other colors. It is a batch I have used
before, not newly mixed, so I have tested this batch of this glaze with
other interior glazes, with no problem.
The inside is a glossy clear, which I have used a million times on this
and other clays, and have never had any problem at all with it. It is a
bought clear, very stable, fires perfectly every time, and this is not a
new jug of it.
The glazes do not touch. There is none of the crackle glaze on the
inside of the cups, or even on the rims.
However, when I did six test cups (to make sure I liked the way it
worked on this shape - I had sketched it, but wanted to make sure), I
suddenly had a problem. The interior bottom of every single one crazed
(I may be using this term wrong - I'm getting a crackle effect that is
only visible once you put coffee or wine or colored liquid in them - I
test coffee in one of every batch of cups. The crackle I'm getting does
not wash off, but leaves thin, spidery brown lines on the inside).
Please tell me why!! It's not a new clay, glaze or firing schedule. The
only thing that I may have done is that I buy the clear as a wet
pre-mix, and I thinned it slightly with water so I could brush a clean
line where the two glazes meet. I have, however, done this in the past
with this glaze, and never had any problem. It seems this particular
outside glaze is affecting the inside glaze, though there is a thin ring
on the outside where they barely meet.
Can anyone help me solve this ASAP? I'm desperate - I have time for two
glaze firings before this show, and if I don't figure out the problem
soon, so I can test one in the first glaze firing, I'll be short an
awful lot of pieces for this show. Please help!
Andie
andie@princessco.com OR andie@andie.net
www.andie.net
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