Abstract: In a method for producing a mold for metal casting capable of being easily disintegrated by water which comprises the steps of kneading alumina sand with hydrous sodium aluminate as a binder, forming the kneaded mixture into the desired mold shape and then passing carbon dioxide gas through the mold to decompose sodium aluminate and harden it; the improvement wherein the kneading of alumina sand with the binder before mold formation is carried out in an atmosphere of carbon dioxide gas to decompose 50 to 80% of the sodium aluminate in advance.

Abstract: A process for producing a self-curable and water-soluble mold, which comprises admixing a suitable amount of water with a mixture consisting of (A) 100 parts by weight of refractory sand particles composed of alumina, (B) 1 to 5 parts by weight of at least one alkali metal phosphate selected from the group consisting of potassium phosphate and sodium phosphate, and (C) 0.2 to 3 parts by weight of an aluminum powder; shaping the resulting mixture into a mold of the desired form; and then allowing the mold to cure spontaneously.