The mixing of dental stone is best accomplished in a large plastic zipper bag, adding 6 oz. of water to every pound of casting material. Simply add measured amount of water to the dry Cast-PRO Dental Stone, squeeze the bag to mix components, and pour into the impression form. Allow 25 to 30 minutes to set. Individual casting material bags are provided in 2 lb., 3 lb., and 4 lb. sizes. Available in Buff or Blue color. Compression: 8,500psi. Expansion: .12%.