Castin Craft Clear Casting Resin is a polyester resin for casting paper weights, trophies, chess sets and conversation pieces. Its also great for embedding coins, dried flowers, biological specimens, and minerals in clear plastic. You can even add transparent dye or opaque pigment to achieve custom results. Castin Craft Clear Casting Resin Catalyst is sold separately. The catalyst MUST be combined with the casting resin for any hardening to take effect. The following is a guide to the recommended ratios for use of casting catalyst with clear casting resin Formula for one layer casting if layer is 18 in. thick use 15 drops per ounce of resin. If layer is 14 in. thick use eight drops per ounce. If layer is 12 in. thick use six drops per ounce. If layer is 34 in. thick use five drops per ounce. If layer is 1 to 1 12 in. thick use four drops p