Styrofoam head mold
I want to make a plaster mold of one of those styrofoam heads they sell at craft stores. What should I put on the head before doing this?
I prefer epoxy
Any type of release that does not contain solvents (which may damage the foam) should work. This could be a wax or something like Vaseline, which is what I would use.
If you want a smooth or rigid surface on the foam you could coat it with epoxy as Justin suggested, then use any release you like prior to molding.