PURPOSE: To prevent the temp. drop of molten brass, to eliminate the reaction between a covering flux and the alloy component and the entrainment of the flux by the molten brass and to obtain the ingot having a low content of nonmetallic inclusions by using zinc oxide as the main component of the flux.

CONSTITUTION: A flux consisting essentially of zinc oxide is used as the covering flux for a brass-base alloy. The zinc oxide is the oxide of the zinc as the main component of brass, chemically stable as compared with the oxide of the Cu as another component and hardly wetted by the molten alloy. Accordingly, such a flux is not melted on the melt surface when introduced into the melt unlike a glass-base covering flux, the flux does not react with the alloy component unlike charcoal, and the nonmetallic inclusions are not increased in the ingot.