Can you remove tarnish from copper?

Mix 1/2-cup distilled white vinegar (or lemon juice, which is more acidic) with 1 Tbsp. salt and enough flour to form a thin paste. Apply the paste to the copper surface and scrub away the tarnish with a cloth or scrubbing sponge. Rinse under running water and buff with a dry cloth to polish.

Can you reverse oxidation on copper?

If you have stubborn copper oxidation due to exposure to air and water, cover the surface of the copper with salt and begin to rub it vigorously with a soft rag. Keep rubbing until the bluish-green discoloration has disappeared.