Cleaning coins is a tricky business. Collectors look at the patina on coins as part of the history of the coin, especially on gold coins, where the better the patina the higher is the value. The only time valuable coins are cleaned is when they are recovered from the ocean. Less valuable coins are cleaned to make them more attractive and shiny when used in crafts or jewelry. The acetic acid in vinegar mixed with the sodium chloride in salt gently removes crusted dirt from copper, brass and dark silver coins, jewelry, other collectibles.
Check the value of your coins in the PCGS coin price guide. If you have a valuable coin do not clean it. The patina that has developed on the coin actually adds to the price.
Place 1 tsp. of salt in the container. Add 1/4 cup of vinegar and stir until well mixed.
Place your brass, copper or dark silver coins in the vinegar/salt mix, laying them in a single layer.
Leave your coins in the vinegar/salt mix for five minutes. Remove the coins promptly.
Dip your coins in a container of denatured alcohol to rinse off the vinegar/salt mixture.
Rinse your coins thoroughly with warm distilled water. You can dip and swish the coins in the distilled water or use a squirt bottle to spray them off. You must remove all traces of vinegar and denatured alcohol.
Gently pat your coins dry with a soft, lint-free cloth.
If your coins are still dirty, repeat Steps 3 through 7.
Replace the vinegar/salt mix, denatured alcohol and distilled water when they become discolored or dirty.
It is tempting to leave coins in the vinegar/salt mix longer than five minutes, but you cannot really tell if the coins are clean until you rinse them and then pat dry.
If you sell a coin that you have cleaned, disclose to the buyer that the coin has been cleaned.
Never use vinegar to clean gold coins.
Never clean valuable coins, the patina adds to the value.
Never scrub coins as this can remove the metal coating.