#1 POTTERY PLASTER - A superior plaster for casting decorative ceramicware, sanitaryware, dinnerware and fine china. Used for making plaster bats, wedging boards, and working molds. This is a relatively soft plaster which may be carved.
HYDRO-STONE - One of the hardest and strongest of all gypsum cements. Used primarily in tooling and high quality art objects. Extremely wear-resistant.
ULTRACAL 30 – Primarily used as a “mass casting material” where the mold is poured from solid gypsum. Most popular gypsum for tooling applications because of its good surface hardness, high compressive strength, and low expansion. Sets gradually.
HYDROCAL, WHITE - Hydrocal is used for making plaster objects, a multi-purpose gypsum cement ideal for both solid and hollow casting. With a normal set of 25 minutes, the setting expansion is somewhat greater than ULTRACAL 30.
For more information regarding plaster and mixing, please see the USG website.