Whether it's a family heirloom, a rare coin, or handmade -- or store bought -- jewelry, you can give your copper items that special look by applying just the right amount of tarnish (also known as patina). Tarnishing can actually increase the value of old coins, more than would polishing them to a like-new shine [source: Metal Detecting World].
Here are several ways to tarnish copper.
Drip acetic acid or vinegar wherever you want the tarnish to appear [source: Metal Detecting World].
- Mix one part yellow sulfur powder and at least five parts Vaseline into a paste. Store the paste in a glass container.
- Coat the copper item with a thin film of the paste and leave it until it attains the desired tarnish.
- Wash off the paste off with gasoline [source: Metal Detecting World].
- Immerse the copper item in a solution of 10 percent ammonium sulfate for 12 hours.
- Remove the item and allow it to air dry.
- Repeat the procedure until the desired tarnish is attained [source: Metal Detecting World].