Mold Max 25 Silicone Mold Making Rubber - Trial Unit Medium Hardness Shore 25A Tin Silicone Rubber Mix ratio is 100A:5B by weight 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.