how to choose a good casting compound? An unbreakable, washable and flexible material that is non-toxic would be best.

Plaster-of-paris would be ok as a cast material, but a softer material (like the washable material that expensive prosthetics are made of) would be better.

paleon7 years ago
SFHandyman. I think you misunderstood the question. You are describing a flexible material (silicone) usually used for molds rather than casts.  For casting, a good, inexpensive material is gypsum cement, which is plaster based but much harder than Plaster of Paris. It is manufactured by U.S. Gypsum in a many varieties such as Hydrocal and Hydrostone.  Search on "gypsum cement" for distributors and retailers.  You can also cast with cement/concrete for outdoor use, resin, or mixtures of resin and gypsum or lime to create faux marble.  This assumes you already have a flexible mold from which to make a cast.  And SFHandyman's suggestion is a good. high-end material for mold making (RTV silicones are mixed in two liguid parts, a base and a catalyst). As far as toxicity goes, the catalysts for both platinum and tin cured silicones are toxic, but once the silicone cures, they are largely inert and safe.  Other common materials for making flexible molds include liquid latex (brushed on in layers) and urethane rubber (mixed in two parts like silicone).  Glen
SFHandyman8 years ago
Silicone is the best casting material. Heat resistant, flexible, won't stick. There are casting materials created specifically to be like human skin in Latex and in Silicone, maybe also vinyl. Silicones can be made with various hardness as can Latex (rubber). Look at the Shore rating for hardness. Platinum cure silicones are mostly non-toxic. If you want guaranteed non-toxic, look for food grade silicone. Dolls are mostly made out of hot melt vinyl. It's easier to keep clean. I expect many prosthetics are made from hot melt vinyl cast in silicone, but there may be newer materials.

Douglas and Sturgess has a ton of information. Look on the site to find the skin like materials. Read through the Ask Zardoz faq. There are questions related to the info you want. Douglas and Sturgess would know the material used in prosthetics.

Douglas and Sturgess supplies casting materials to artists, and special effects industries, plus regular folks like me. You can order from them over the web.