Care Tips for Brass Jewelry : Brass is generally coated with conventional polishes, which is basically a thin film of oil to help prevent tarnishing. Use the same techniques for cleaning all precious metals when cleaning Brass. You can delay the tarnish by proper storage and care. To avoiding exposure to the air, store it in a zip lock bag. Be careful when applying any polish, as the Brass can turn black if you over apply polish or due to its misuse.