Fredrick Paget on fri 1 dec 00
Hi, USG pottery plaster #1 is what I use. It is better than the cheapest
"plaster of paris". It is smoother and does not set up as fast. I get it
from my local ceramic supply stores, Leslie in Berkely CA or Clay people in
Richmond CA. I use it at the recommended 70 pound density. That is 100
pounds of #1 plaster to 70 pounds of water or 1 kilo of plaster to 700 ml.
of water.
You can make a nice hump mold by centering a tub of plaster in its liquid
stage on your wheel and spinning it at constant speed till it sets up.
Spinning a liquid in a tub produces a parabolic surface and the faster it
spins, the deeper the curvature is. If the speed is fast enough for the
edge of the parabola to climb over the edge it will spill plaster all over
the place! Try this with a tub of water until you are confident you won't
spill it over the edges.
After the parabola hardens you now have a mold in which you can pour your
humps. Use mold soap for release agent. A spritz of rubbing alcohol will
pop the bubbles or alternatively you can sweep the surface with the flame
of a propane torch.
Fred Paget
>From Fred Paget, Marin County, California, USA
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