Brass tarnish is not damage

Brass reacts with air. The copper in the alloy oxidises and forms a dark film across the surface. That film is stable, and it slows further reaction — the metal underneath is untouched.

So tarnish is a choice, not a problem. A piece kept bright needs polishing every few weeks. A piece left alone darkens over a year or two into a deep brown that many people prefer, and then stops changing.

If you want it bright: half a lemon and a spoon of salt, rubbed on and rinsed off immediately, works as well as commercial polish. Dry it completely afterwards — water left standing is what causes real damage, the green corrosion that pits the surface.

One exception. Anything you eat or drink from should be polished, not left to patina. Keep it dry between uses.