The material used to manufacture sand molds is called molding material. The material used to manufacture sand molds for chemical pump castings is commonly referred to as molding sand, and the molding material used to manufacture sand cores is called core sand. Usually, molding sand is made by mixing raw sand (mountain sand or river sand), clay, and water in a certain proportion, with a viscosity of about 9% and water of about 6%. The rest is raw sand, and sometimes small amounts of additives such as coal powder, vegetable oil, wood chips are added to improve the performance of molding sand and core sand.

The quality of molding sand and core sand directly affects the quality of castings. Poor quality of molding sand can cause defects such as porosity, sand holes, sand sticking, and sand inclusion in castings