05-31-2007, 09:23 AM
Back when I started making masks I used a product called smoothcast 305 from smooth-on. SC305 is a 2 part polyurethane resin that fully cures in about 30 minutes. It cures white and I’d say is ivory in appearance. You can cast urethane resin is Latex, silicone and urethane rubber molds. I would recommend using silicone as a mold material. Silicone requires no release agent and you can cast just about anything in a silicone mold, even some metals.For silicone, if you've never worked with the stuff it can be a pain to use, I would use Rebound 25, also from smooth-on. Rebound 25 is a platinum based silicone that’s brushable without having to add in any thickeners, for full head pieces and pieces with a lot of undercuts this is a really good rubber to use. The molds I use for my fiberglass masks are made from this stuff, I’ve made 5 molds using this RB25 and never had any problems with air bubbles or surface imperfections. A lot of pros would say to use GI1000 silicone rubber, if you’re molding a complex piece you might want to look into GI1000 as it’s probably the best mold rubber you can buy.One thing I should mention about polyurethane resin. Polyurethane resins are very sensitive to atmospheric moister. What ever the manufacture recommends for working conditions should be followed to the letter. I stopped using urethane resin because here in NY the weather can get really wacky, I’ve had great success using urethanes in the warm dry months of the year, when fall/winter came rolling around the stuff just wouldn't set up properly.Hope this helps.Jeff-