Abstract: Method of producing a mold from a ceramic composition which can be washed-out with water after use thereof in a molding process, the method including forming a ceramic composition by mixing from about 30 to about 80 weight percent of at least one hemihydrate including alpha-calcium sulfate hemihydrate or beta-calcium sulfate hemihydrate, from about 5 to about 45 weight percent of fire clay, and from about 5 to about 25 weight percent of at least one silicate-based filler. About 100 parts by weight of the ceramic composition are mixed under stirring into from about 46 to about 54 parts by weight of water to form a slurry. The slurry is poured into a formation mold suitable for forming the desired mold and the slurry contained in the formation mold is allowed to set and form a set body. The set body is then removed from the formation mold and dried to provide the mold.