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recycling plaster of paris used in glass casting Answered

Actually it is a question again on same topic but the way the plaster has been used here may change the way it can be recycled. I use plaster of paris to make moulds for glass casting.I want to know if the plaster from these moulds can be recycled since they already have been heated for 24 hours in 800 degrees temperatures. Are the properties lost once heated that high?



10 years ago

although it is technically possible to return the plaster to pre-hydrated state by "calcining" it at 1800F, I've never had any success in trying this. My guess is that true calcining takes so much time and a controlled atmosphere that it's not practical for the small batch kiln person. Anyone who says just add water again hasn't tried it.

no really... If you powderise the plaster of paris you can use it again. putting it in a kiln for a long time will take all of the moisture out and make it brittle.

Plaster setting up is a chemical reaction with the water. Once you have driven off the chemically bound water, you can grind it up and re-use it, but trying to get it fine enough to restore the original properties might not be worth the effort and cost.