RTV (room temperature vulcanizing) platinum-cured silicone – used for heat and pressure sensitive materials such as organics, wax or resin prototypes. It has very low shrinkage, high tensile strength and a very long life span.
Vulcanized Rubbers – natural rubber or silicone – requires heat and pressure to cure and is used on metal masters. It has 3% to 7% shrinkage depending on type, high tensile strength and a very long life span.