PolyFoam R-8 is a two-part, rigid polyurethane casting foam. This self-skinning foam has a free-rise density of 8 lb/ft³, but should be cast at a density of 8 to 20 lb/ft³ to achieve good surface detail and mold fill. Generally, PolyFoam products should be cast in TinSil® or PlatSil® silicone molds. Barrier coats (e.g., a fast-drying primer paint) can be applied to silicone molds before casting foam in order to produce pre-primed parts right out of the mold. These foams can also be poured into Poly 74 & 75-Series polyurethane rubber molds that have been coated with PolyCoat Sealer & Release Agent.