Thread: molding with plaster

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Has anyone ever made a decent mold of a complex object with plaster of paris? I am going out to Michaels in a little while to see if they carry any cheap mold making materials, but I have a couple cartons of plaster I got from Wal-Mart a year or so ago the I need to use up. I have a plastic skull that has the mold lines still on it and I was thinking of trying to use them to make a 3-piece plaster mold of the skull. Does anyone have any advice? I have heard of using the silicone caulking from Wal-mart also, but earlier experiments with it didn't work out so well for me lol. If anyone knows other cheap materials (I only have $15 to spend lol) I could use to make a mold, that would help immensely. I am needing to make some hands and skulls; possibly a face later on if all goes well. Thanks

You don't want to make a mold of a plastic skull in Plaster of Paris. Why?
a) When molding a hard object, use a flexible mold. soft object=hard mold
b) plaster of paris is very weak. It is very likely that the mold would break. There are strong plasters around, however, such as UltraCal-30 and Hydrocal
c) If you want to make a hard skull in the end (either out of 2-part foam or plaster), you need a soft mold to cast it from (same principle as #1)

I think you should keep trying with the silicone, or try latex