Brass is an alloy of copper and zinc. In sea water, the zinc is anodic to the copper and it corrodes leaving a porous, spongy mass of copper, hence de-zincification. This should not occur to brasses in which arsenic has been added and whose zinc content is less than 37%. A similar to aluminium bronzes. About 4% a called de-aluminification, can occur to 5% nickel avoid this problem but trouble may still take added to the bronze can place at welds.