Conservation problems common to art and antiquities made of metal usually result from interactions between the metal and its recent or past environment. Some metal objects or artifacts may have been exposed to adverse burial conditions, but even in more protected environments, metal objects may be damaged by humidity and air pollution. Since metals are reactive with their environments, the best conservation practice is to maintain safe, controlled storage and exhibition conditions. In the event that an object's environment cannot be controlled - for example, when a bronze sculpture must be displayed outside - it can be protected by a suitable surface coating. Metal objects may also suffer mechanical damage, such as cracks, dents, or breaks, that require repair. This essay describes the main causes and processes of corrosion of metals used to make decorative and fine art objects - silver, bronze, and brass - and the methods available to a conservator for preventing and treating damage to such artifacts.