Brass castings are made by heating copper and zinc in pots in a furnace, and pouring the alloy into a mold. The principal differences between molds for brass and molds for iron are that brasswork molds are made from finer and cleaner sands; that in brass molding a greater allowance must be made for contraction; and that different facings, parting sands, and finishings are used. Very nearly the same blackening mixtures are used in brass molding as in iron molding, and the methods of drying and venting are practically the same in both classes of work. The method of cleaning brass castings is the same as that of cleaning iron castings.