The negative space of the wooden mold is pushed into the molding material, which is typically a large container of sand. This is not your typical sand you find on the beach, but is mixed with other products to have wet, packing characteristics. The molding or foundry sand is ideal for pouring liquid metal into, as the tiny silica particles will refract the temperature of the liquid. When using a wood pattern to make a cast piece, the interior core pattern shaped like the product needing to be cast is placed between the two outer molds, and sand is poured in. In this process, the molds are pushed together to squeeze the pattern that has been placed in the sand. Once patterns or molds are removed from the molded sand, liquid metal is poured into the impression left by the pattern in the sand. The molding material can then be reused each time to create new metal castings.