Brass is one of the most rewarding materials to restore but also one of the easiest to get wrong. Knowing when and how to polish it comes down to understanding both the history of the piece and its purpose. Brass tarnishes naturally as it's exposed to air and moisture. Humidity, oils, pollutants, and even nearby finishes can speed this up. Left untreated, tarnish deepens, though full corrosion takes much longer. In many cases, polishing is purely cosmetic and perfectly fine, especially if the pi