Aging and tarnishing
As copper-based alloys, muntz metal and naval brass tend to tarnish with age. Tarnishing occurs as a result of exposure to air causing the metal to oxidize. In some cases, these metals are selected due to the appearance they take on as they age. However, other customers opt to lacquer their brass or bronze products to avoid tarnishing.
Cleaning muntz metal / naval brass
If a tarnished appearance is not desired, or if dirt and grime have marred the surface of muntz metal or naval brass, these metals can be restored and cleaned using a solution of 50% lacquer thinners and 50% water. When cleaning muntz metal or naval brass, clean only with the direction of the grain, rather than against the grain. Use a lint-free cloth to clean the surface, then rinse the metal, and finally wipe dry with another clean, lint-free cloth.