Donna J.S. Causland on mon 20 mar 06
Lots of questions on moulds lately.
One piece mould for slipcasting bowls:
Yes, watch for thickness forming, dump, let dry to leather hard,
trim, wipe with sponge. Voila. I do get some thicker drips in the
bowl but remove them with a loop tool, then sponge over.
To make one piece moulds:
I start with a hand formed clay bowl, but way thicker, and fill the
void with scrap. (so the air bubble doesn't pop it off the base and
float up when you pour in the plaster. Now, there's a mess!)
I use mould boards joined with clamps and greased with vasiline to
custom size the outer box. There are lots of books with pics of this.
Also, sureform the sharp edges to help avoid plaster contamination.
This makes nice looking moulds. Craftsmanship in everything.
Mixing plaster:
Weigh your plaster and water. Read Donald Frith.
It's 7 pounds water, then gradually add 10 pounds plaster.
That's the ratio, so you can do the math for different size batches.
Air release:
Thank you Stephanie. Spray air nozzle close, all around edge.
I don't use a notch in the edge. It's amazing, it works.
My input here is that I use my airbrush on a C02 tank. Cheap and
lasts
a long time.
OK, that's all I know about that.
Ya'll have a nice day.
Donna
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