To be safe, after cleaning with vinegar or lemon juice, it is best to soak the coin in distilled water with a little baking soda added for a week. (Never use vinegar or lemon juice to clean bronze coins.) Silver coins can also be cleaned by placing them in an aluminum can filled with a baking soda and water mix.
Distilled water is recommended as tap water contains chlorine. The coin is dipped into olive oil which according to Hudgeons, works best for common copper or bronze coins.
If you do not have a toothbrush, you can use another stiff brush. However, never use a metal brush because the bristles will scratch your coin. Soak in olive oil. Washing your coins with olive oil is the safest way to clean your coins as you cannot leave the coins in olive oil for too long.
Although all the experts advise against cleaning coins as it could seriously reduce their value, sometimes, at least with Ancient Coins, where there is really heavy encrustation, it is the only way to remove enough to reveal any detail.
Most Cleaning is Destructive: It Can Literally Change the Surface of a Coin. Any cleaning that requires rubbing leaves microscopic scratches. They are not apparent to the naked eye, but a collector will see them. A collector will look for them.
Never use metal polish or acid dip to clean your coins! Using these chemicals will cause abrasions or chemical reactions with the metal, permanently damaging your coin. This damage can never be fixed or undone. Additionally, these chemicals can be caustic and cause injury or even death.
The cleaning of the coin is made by friction of the piece in a cotton flannel with a small amount (a pinch) of calcium carbonate – a neutral product, with a very thin granulation not to scratch the piece (approximately the same granulation as toilet talcum). Calcium carbonate may be used in any metal.
Soak your coins in olive oil (it is slightly acidic), WD40, or distilled water (not tap water or spring water). Few people have the patience to soak them long enough. How long - at least a few days, but weeks is usually better.
Boil 1 1-/4 cups of water, add 2 teaspoons cream of tarter, 2 tablespoons vinegar, and 2 tablespoons salt. Add coins and boil for about 3 minutes or until tarnish is removed. Remove coins from water and dry with a soft cloth. This puts a coppery pink onto pennies.
1. The most important thing NOT to do is clean your coins. Cleaning rare numismatic coins will significantly reduce their value – plain and simple. Although you don't lose much by cleaning a coin which derives value only from its silver content, it's not worth the risk.
The salt and acetic acid in vinegar do the trick. Hot sauce, like Tabasco or taco sauce, also will remove the oxides off pennies. As in ketchup, salt and vinegar are both in hot sauce. Coke and off-brand colas will quickly remove the tarnish.
The vinegar and salt mixture dissolves the outer layer of dirt. Flip the pennies over and wait another 30 seconds. Then remove them, rinse them with water, and dry. Now you have two clean, shiny pennies!
Pour your coins into one bowl and fill with cold water until the money is well covered. In the other bowl, pour about 1 teaspoon of baking soda. Dip the toothbrush into the bowl of baking soda and scrub the coins. The baking soda should remove any dirt and grime and won't scratch the metal.
Copper oxide dissolves in a mixture of weak acid and table salt-and vinegar is an acid. You could also clean your pennies with salt and lemon juice or orange juice, because those juices are acids, too.
Let your coins sit in distilled water for 24 hours. Note: distilled water is not the same as tap water. You can purchase distilled water at your local grocery store. After letting them soak, rub them gently with a soft bristle toothbrush.
Coins that are obviously dirty can be run under water (with a very mild detergent) and left to air dry. A short soak in olive oil may remove unwanted gunge. For cleaning corroded coins the damage is already done, they will forever show pitting into the coin surface. This is as far as anyone should go with cleaning.
Here are some of the key benefits of ultrasonic cleaning: Ultrasonic cleaning is a non-invasive method of cleaning coins that does not involve any physical contact with the surface of the coins. This means that there is no risk of scratching, scuffing, or damaging the surface of the coins during the cleaning process.