Lisa Harrington on fri 16 aug 02
So I made this torso sculpture out of solid (except for the armature)
stoneware clay (cone 6) with the intention of making a mold for bronze
casting. To make the mold, I had to coat the wet clay with shellac to
prevent the sulfer content of the clay from lousing up the mold rubber.
After I removed the rubber mold, the clay piece was still intact. Some
of the shellac stuck to the rubber, but some also stuck to the clay. So
my question is: Is there any reason why I can't hollow this thing out
and pop it in the kiln? Would the remaining shellac be a problem, or
would it just burn off?
Also, If I don't intend to glaze the finished piece, should I fire to
maturity, or just bisque?
Thank you again!
Lisa
Snail Scott on fri 16 aug 02
At 11:07 AM 8/16/02 -0400, you wrote:
>So I made this torso sculpture out of solid (except for the armature)
>stoneware clay (cone 6) with the intention of making a mold for bronze
>casting. To make the mold, I had to coat the wet clay with shellac to
>prevent the sulfer content of the clay from lousing up the mold rubber.
Your waterbased stoneware clay has that much sulfur
in it? Are you sure? Many types of plasticine
(oil-based) clay contain enough sulfur to mess up
mold rubber, (it's added to improve its handling
characteristics,) but I never heard of a 'regular'
clay having anything but trace amounts. Weird!
>After I removed the rubber mold, the clay piece was still intact. Some
>of the shellac stuck to the rubber...
That shouldn't have happened. Did you use a mold
release over the shellac?
>So
>my question is: Is there any reason why I can't hollow this thing out
>and pop it in the kiln? Would the remaining shellac be a problem, or
>would it just burn off?
No problem, go right ahead. It'll burn off.
>Also, If I don't intend to glaze the finished piece, should I fire to
>maturity, or just bisque?
Fire to maturity whenever possible. The piece will
be stronger, and most bare clays are more attractive
when fired to vitrification. I've occasionally fired
pieces only to bisque, when the final surface was a
non-fired one, but I've always regretted it when it
came time to ship the damn things.
-Snail
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