Copper will never rust for the same reason as bronze — it contains too little iron. Though it will not rust, copper can form a green film, or patina, on its surface over time. However, this patina will not flake the way rust does. Instead, it creates an even, thick coating on top of the copper itself.

Does copper tarnish or rust?

Copper, Bronze and Brass

These three metals contain little or no iron, and so do not rust, but they can react with oxygen. Copper oxidizes over time to form a green patina, which actually protects the metal from further corrosion.

Does copper corrode iron?

Copper does not rust, however, it does corrode. Copper is naturally brown and turns a shade of bright green as it corrodes. While some consider copper's reaction to be tarnish rather than oxidation, the metal still undergoes a similar “rusting” process.