Bronze will oxidize when exposed to air, developing a patina coating. A brown, black, red or blue to green coating on bronze is a sign of normal, harmless corrosion. This outer layer protects the inner layers of the bronze object from deteriorating.

Does bronze darken over time?

The important thing to remember is that all bronze darkens as it ages, but by with proper care of the surface of your sculpture, you may be able to slow this oxidation process for a time. -Depending on preference, some people really like the look of an aged bronze, while others prefer a fresh, new patina look.

What causes bronze to darken?

Heat will darken the color as well as reduce mottling. Liver of Sulfur is the classic darkening patina for bronze, brass, and copper. Depending on the surface, the strength of the solution, and the application method, it will produce a golden brown to a burgundy black patina.