A friend of mine inherited a huge cache of plaster molds from an aunt who was much into casting all kinds of doo-dahs in them, then firing them and glazing them. He also inherited an automatic electric kiln (the one I use occasionally) along with them. He is not into ceramics at all, and has zero knowledge of the craft, but is very interested and wants to learn at least enough to allow him to use these molds.
He asked me for advice (talk about the blind leading the blind) and I told him I thought he just poured casting slip into the molds, slosh them around for awhile, pour it out, let it dry and open. He'd never even heard of casting slip. I offered to try and help him out, hence this post... There are a few questions I cannot answer:
- Is there any particular kind of casting slip he should get? The molds are things like vases, still lifes, basically the kinds of articles people refer to as "gifts."
- Should some kind of mold release agent be used?
- How long should the slip be left in the mold? Should it be rotated? Topped off? Should the hole be sealed with some kind of tape?
- To what cone should the casting be fired? Is this bisque fired forst, then glaze fired, or is it all done at once?
I appreciate any advice. Many thanks...
Fred