The carbon and silicon percentages are reduced to the amount approximately consistent with those in steel. This is done using pig iron or gray iron casting scrap and reducing the amount of carbon through the addition of relatively pure steel or wrought iron scrap in a well heated cupola furnace. The percentage of carbon is typically between foundry cast iron and wrought iron.
Journal of the Iron and Steel Institute, Vol. LXXIII, p. 511. c 1907.