This produces a dark patina on nickel, brass, copper, and other metals (though not aluminum or stainless steel). The color may range from brown to black to reddish-purple tones, depending on the exact alloy. On an object that will be handled, the patina can be sealed with a spray such as Dull-Cote, or with a paste wax. Contains a corrosive acid; gloves and eye protection are a good idea. Best used on a clean, degreased surface. If Blacken-It does not appear to work, the metal object may have a clear coat that can be removed with lacquer thinner.