Mold Max 40 Silicone Mold Making Rubber - Trial Unit Medium Hardness Shore 40A Tin Silicone Rubber Will reproduce the finest detail Good for making molds used for casting resin, plaster and wax. Can be thickened with Thi-Vex thickener for brush-on application and effects. An infinite number of color effects can be achieved by adding Silc Pig silicone pigments or Cast Magic effects powders.