Dental Stone is the best known material for reproducing footwear and tire tread impressions in soil, sand, and snow. The mixing of this product is best accomplished in a large 4 mil. plastic zipper bag, adding 6 oz. of water to every pound of casting material. Simply add the measured amount of water to the dry dental stone, squeeze the bag to mix components, and pour into the impression form. Allow 25 to 30 minutes to set. Oversize shipping applies. Available in Buff or Blue color. Compression: 8,500psi. Expansion: .12%.