hey guys i have a noobie question. i have a styrofoam piece that i need to vaccumform. now i know it would just melt but is there something i can coat the styrofoam with so it could withstand the heat of the plastic?
I've never vac formed before, but from what I understood the problem with foam pieces is the vacuum causing the master to be crushed. If your piece is something like craft styrofoam then I think your piece will likely cave in under vacuum pressure.
You can brush on 5 or 6 coats of joint compound (the dry powder stuff used for house 'dry wall' fabrication) and that would give you a thick enough skin to get a few vacuumpulls off your styrofoam sculpture. The thin plaster shell will protect your foam, but eventually the heat will deteriorate the foam underneath the shell and you will be in danger of crushing the plaster shell into that void area. Usually I brush on a layer every 3-6 hours. takes a couple days to cover a mold (but then again i live in the humid south, and that might be the main factor in my drying time)
If you need/want to get more vacuumpulls than a few, I would suggest you pull a mold of the sculpture, pour a Hydrostone or Ultracal plug-mold from that, and go from there.