Silicone Rubber - Tin Cure
Also called condensation-cure silicone, these are high-tear silicone rubbers that are known as the "work horse" of the industry because of their performance and economy. Tin cured silicone molds are used for casting wax, gypsum, polymer modified gypsum, etc. but are best known for standing up to production casting of urethane, epoxy and polyester resins. They are also good for casting low temperature melt metal alloys.