A muscle mixture should be designed so that it has the following qualities: at high temperature and in the balanced conditions, the solidification of the metal should be proportional to the metal strength. A muscle that maintains its strength for a long time, at a high temperature, causes a warm break or crack in the casting piece. During freezing, if the metal is disintegrated and crushed, the muscle must retain its strength until the metal forms a solid crust around it, and then quickly loses its strength when the metal contraction begins, and thus, avoiding metal cracking, makes a smooth surface against molten metal, so that the metal cannot penetrate the muscle, possesses sufficient hardness, and proper resistance to the flow of molten metal, otherwise, it may crack, break, etc. The muscle mixture should also be resistant to heat from the melting temperature, and be not affected by the mold or the atmosphere created by the molten metal.

Another application has been in the iron, steel and cast iron industry since s. Blends of sand and sodium silicate are used to make molds and steel wires in casting by compressed carbon dioxide gas in a compact form with an initial preparation. The initial hardening of the sand-sodium silicate blend in the presence of carbon dioxide causes a chemical reaction between carbon dioxide and sodium silicate.