How can I made multiple plaster molds from one clay model?

Hello everyone,

I want to use a clay model and have it cast into a two part plaster of paris molds, so I can use it for papier mache.
My problem is, I want to have several identical molds of the original copy. I can't figure out how I can do this though, as I would have to pick to clay/plastercine out of the original mold. Has anyone got any ideas to get around this? I was thinking maybe I could make the first plaster mold, make a rubber copy of the model inside and then from there, make the other molds. Could this work?
Any help or advice would be brill,



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yours (author) 6 years ago
Thanks, will give it a go!
yours (author) 6 years ago
Thanks for your comments :)

Aeray -

So it's possible to use a plaster negative to make a plaster positive? I guess it is all about the releasing agent then.

Also I'm in the UK and googled the mold soap to see if they do it here but it seems I can only get this from America. Could anything else work if casting plasters?

Thanks again
aeray yours6 years ago
Vaseline (petroleum jelly) will work, as will Murphy's Oil Soap or "green soap" (which is medical soap often used by tattoo artists). Put the soaps on in 2-3 thin layers and let it dry before casting. For the Vaseline, just put on a thin even layer.
aeray aeray6 years ago
And re-treat your mold occasionally.
aeray6 years ago
1) Make the initial model from clay.
2) Cast the two part plaster mold.
3) Dig out all of the clay from the mold.
4) Treat the mold with mold soap (look at the very bottom of the page).
5) Cast a plaster "original" using the mold.
6) Use the plaster "original" (and the mold soap) to cast additional molds.

Sounds like a good plan