When old coins get tarnished and collect dirt, your first instinct may be to clean them so they will retain their original shine. However, if particular coins are at all valuable, you may end up devaluing them by cleaning them. It’s always a good idea to have your coins checked by a professional before attempting to clean them. You should be safe to clean pennies and Jefferson nickels, as they are not likely to be very valuable.
Clean Ordinary Coins
Start cleaning your coins by running them under water. Don’t scrub the coins, as that can scratch the surface. If at all possible, use distilled water instead of tap water.
Brush on a small amount of baking soda while the coin is still wet. Gently brush it on using an old toothbrush, being careful not to scratch the coin. Baking soda can bring back a coin’s shine.
Try soaking a coin in household vinegar for a few minutes if the above methods didn't work. If that doesn’t help, gently brush on some vinegar with a toothbrush. Rinse the coin with distilled water and let it air-dry on a soft cloth.
Clean Copper Coins (Pennies)
Clean pennies by applying ketchup. Pour a small amount of ketchup into a container and place the penny on top of the ketchup. Allow the penny to soak in ketchup for about five minutes. You also can rub the coin with your fingers.
Rinse the coin with distilled water and allow it to dry on a soft towel.
Apply vinegar and salt instead of using ketchup if you prefer, as it has the same effect. Mix a small solution of vinegar and salt in a container and let the coin soak in it for a few minutes. Rub the coin with a soft cloth. Rinse the coin and let it air-dry.