Silicone Mold Rubbers
Polytek® manufactures a full range of two-part, room-temperature curing silicone rubbers that offer great flexibility, tear strength, chemical resistance, and release properties. Silicone molds can be used to cast a variety of materials, including polyurethane, polyester and epoxy resins, polyurethane foam, plaster, wax, concrete, low melting metals, and more.
Silicone mold rubbers are more expensive than polyurethane rubbers, but well worth the expense when the user does not want to use release agent when casting resins and foams.
Polytek® manufactures two different types of silicone rubbers: platinum-cured (PlatSil®) silicones and tin-cured (TinSil®) silicones. Read about their differences below in the section titled A Comparison: PlatSil® vs. TinSil® Silicone Mold Rubbers.
Select a product line below to view individual product options:
- TinSil® silicones are condensation-cure systems that shrink slightly on cure (~1%) compared to addition-cure PlatSil® silicones, which do not shrink on cure.
- Cured TinSil® silicones have shorter library life (2 to 5 years total) compared to PlatSil® silicones.
- TinSil® silicones are slightly less expensive than PlatSil® silicones.
- Liquid PlatSil® silicones are more sensitive to certain materials (e.g., sulfur, tin compounds, Bondo) and suffer from cure inhibition (uncured surface material) more often than TinSil® silicones.
- Cured TinSil® molds can inhibit some casting materials, including PlatSil® silicones, Poly-Optic® Clear Casting Resin and many polyurethane rubbers.
- There are skin-safe platinum-cured silicones available in the PlatSil® product line: PlatSil® Gels.
PlatSil® rubbers are platinum-cured (also known as addition-cure), room temperature-curing silicones that are used to make flexible, high-strength molds and parts. PlatSil® molds are often selected over other mold materials (e.g., polyurethane rubbers) because of their excellent release properties. They also exhibit long library life and low shrinkage on cure compared to other mold material options.
TinSil® rubbers are tin-cured (also known as condensation cure), room-temperature curing silicones. Molds made from these rubbers exhibit high tear strength, good release properties, and resistance to high temperatures.