The acid finishes actually are colors produced in acid reactions with brass & copper. In areas not exposed to the elements, the acid finishes should maintain their appearance for years. However, in an exterior location, especially a salt-air environment, the colored fixture will start developing hints of natural green patina, eventually giving way to this coloring at the closest of oceanfront locations. These fixtures were made with a dark bronze finish, but because of their oceanfront location, the natural patina has begun to show. This is a natural process where salt air reacts with the copper in the brass alloy. Fixtures away from ocean locations can maintain their black, dark bronze, or nickel acid finishes for years. Simply supply the finish code at the end of the fixture specification. For example, the MB1-17-FIN-DB and L-013-S-FIN-DB shown here. Again, standard unfinished fixtures require no finish code.