Abstract: A casting mold which is molded by heating mulled sand including a mixture of refractory molding sand particles, an inorganic water soluble binder and water, wherein the inorganic water soluble binder is made of a combination of a sulfate compound such as magnesium sulfate heptahydrate and a borate compound such as sodium tetraborate decahydrate. The casting mold is formed by baking the mulled sand in such a manner that at least part of the sulfate compound retains water of crystallization therein and the borate compound is once fused and then cured.

Abstract: A casting mold which is molded by heating mulled sand including a mixture of refractory molding sand particles, an inorganic water soluble binder and water, wherein the inorganic water soluble binder is made of a combination of a sulfate compound such as magnesium sulfate heptahydrate and a borate compound such as sodium tetraborate decahydrate. The casting mold is formed by baking the mulled sand in such a manner that at least part of the sulfate compound retains water of crystallization therein and the borate compound is once fused and then cured.

Abstract: In a water-soluble casting mold according to the present invention, after casting sand is obtained by adding a water-soluble binder containing an inorganic sulfate compound such as magnesium sulfate or the like easily solved in water and water to a refractory granular material for casting sand, the casting sand is dried by microwave radiation or the like in such a manner that the inorganic sulfate compound in the binder is kept retaining at least a portion of crystal water and accordingly, since the inorganic sulfate compound exists in hydrate state in the mold, the mold after drying is provided with good water-solubility and a sufficiently high strength as well, thereby it is possible to recover easily and use repeatedly the binder.