This instructional mold making tutorial video shows how to make a silicone block mold for casting resin, wax, foam, and many other materials using Smooth-On Mold Star™ 15 platinum silicone mold rubber.
Mold Star™ 15 is an easy to use Shore 15A platinum silicone that is mixed 1A:1B by volume (no weighing scale necessary). It features a relatively low viscosity and vacuum degassing is not required for most applications. Pot life is an extra-long 65 minutes. Mold Star® 15 cures overnight to a soft, strong rubber that is tear resistant and exhibits very low long term shrinkage.
Mix parts A and B as directed, carefully scraping the sides and bottom of the mixing container.
Allow Mold Star™ 15 to cure, it has a cure time of 4 hours at room temperature (73°F/23°C)