Some other options to use in place of vinegar include orange or lemon juice. Like vinegar, citrus juice is acidic and wears off copper oxide on coins.
Keep in mind that adding more salt to the solution makes it stronger. Mix in extra salt if you wish, but keep a close eye on the coins to avoid damaging them.
For a more gradual treatment, leave the coins out of the bowl. Instead, dip a soft-bristled toothbrush into the vinegar solution and scrub the coins with it.
Hold the coins under a little bit of running water to ensure all of the cleaning solution rinses off. Don’t leave them in a bowl of water, since the vinegar solution and copper oxide will end up in the bowl and on other coins.
Soak the coins in more salt and vinegar if they still look dirty. It may take a few treatments, so work gradually and wash the coins off each time to avoid damaging them. Vinegar solutions are effective for removing dark spots on coins, but they also tend to make coins look a little dull. Shine the coins to make them look better.
Hot sauce and brown colas are some other household substances that work well on copper coins. [6] X Research source If you don’t have ketchup or another acid, try using a metal polish from a general store. It works similarly to ketchup.
If you don’t have a brush available, leave the coins submerged in the ketchup for at least 5 minutes. Check back on them every few minutes, especially if you use a highly acidic substance like cola, to avoid damaging them.
Newer coins, such as relatively shiny pennies, tend to dull a little when washed in acid.
Clearing away the dirt now makes the coin look clearer once you add the oil to it.
Use sparing amounts of oil to avoid damaging coins. Remember, you can always try cleaning a coin again, but you can’t reverse mistakes.
Repeat the treatment with more oil as needed. For a stronger treatment, let the coins soak in oil for about a day, then scrub them with a soft toothbrush.
Add more baking soda and water as needed for larger batches of coins. As a general rule, make the paste at a ratio of 3 parts baking soda to 1 part water.
The baking soda isn’t acidic like vinegar and citrus juice solutions, so leaving the paste in place for a while is safe.
If the coins still look a little dull, try treating them with more paste. Very old or dirty coins require the extra effort.
