FMC® 205 is a polysulfide rubber mold compound that cures overnight with negligible shrinkage to a lasting durable rubber that will perform in production. The mix ratio is 100 parts of Part A to 12 parts of Part B by weight. FMC® 205 cures to a Shore hardness of 12 A.FMC® 205 is ideal for those applications that require capturing intricate detail from a variety of model surfaces. Unlike polyurethanes, FMC® 205 is not sensitive to moisture and can be poured directly over wet plaster or water/sulfur based clays. Common applications include molds of sculpture (lost wax process), casting various gypsum products and waxes.