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.

Abstract: A process for producing molds, models and tools from hard gypsum and/or cement including applying at least one base layer composed of a binder to a model from which a mold is to be made and which has been provided with an unmolding agent, and pressing onto this base layer a glass fiber reinforced molding composition composed of 95 to 0 weight % .alpha.-calcium sulfate hemihydrate, 0 to 95 weight % cement, 0.5 to 8 weight % glass fibers and 0.5 to 4 weight % suspension agent, with reference to the dry weight, as well as water in a wet-on-wet process and unmolding the resulting laminate after it has set.