Simply place one coin in a glass or tub and pour coke over the top, enough so that it is fully submerged in the liquid. Leave the coin to soak for. If you want to go ahead and clean corrosion off of your old coins, baking soda likely is the safest route to follow. Wet the affected coin with clean. Vinegar (or Lemon Juice) and Salt This method is the best way to clean your pennies, and it will produce a very bright orangey-copper color on.