Statuary bronze is a term given to a range of copper alloys featuring a rich umber patina. The base material for this patina process can be performed on any copper alloy, including bronze, brass, and raw copper sheet. Copper alloys are transformational, meaning that they will continue to change over time.
Many successful patinas on brass and bronze alloys use heated copper nitrate solutions or pastes made from copper sulfate and copper acetate. The processes should be performed by professionals experienced with working with chemicals and corrosives. Because many of the treatments involve heating the metal fabrication with a torch, large objects or objects with flat, thin planes are difficult to color successfully. Cast forms and smaller fabricated shapes will color adequately if cleaning is performed correctly.