Smooth-On Mold Star rubbers are easy to use platinum silicones which are mixed 1A:1B by volume (no weighing scale necessary). Mold Star silicones feature relatively low viscosities and vacuum degassing is not required for most applications. Mold Star silicones cure to soft, strong rubbers which are tear resistant and exhibit very low long term shrinkage. Molds made with Mold Star will last a long time in your mold library and are good for casting wax, gypsum, resins, concrete and other materials. Cured Mold Star rubber is heat resistant up to 450°F (232°C) and is suitable for casting low-temperature melt metal alloys. Note: THI-VEX is NOT compatible with Mold Star rubbers.MIX RATIO: 1:1 by volume; POT LIFE: 50 mins; DEMOLD TIME: 4 hrs; SHORE A: 15; COLOR: Green. Adult Supervision Required. Keep Out of the Reach of Children.