Take the coins out and sprinkle some baking soda over them; then use a soft-bristled toothbrush to brush them clean. Rinse them out thoroughly with hot water; using tongs or gloves to hold them to avoid burning your fingers. Place them on a soft, cotton towel and leave to air dry.
Before cleaning old coins, consider that appraisers and coin experts suggest not cleaning collectible coins yourself because the coins may lose their value. Using chemical cleaners or scrubbing the coins can leave behind scratches and marks, easily seen by a skilled coin appraiser.
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.
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!
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.
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.
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.
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.
Even touching the coins introduces oil and dirt to the coin's surface. Since oil and dirt cannot be removed without cleaning, a small touch can cut a coin's value in half or even more because, again, numismatists would rather have an oxidized but untouched coin than a shiny but damaged one.
Generally, it is better to leave your antique metal currency alone than it is to try and erase all the grime and grit off of those coins. Cleaning or polishing rare coins devalues them. So, if you're planning on selling them, get an appraisal before attempting to clean your coins.
Collectible or valuable coins should not be cleaned as cleaning almost always reduces their value and rarely improves their grading. Though it may seem that a bright, shiny coin would be more appealing to coin collectors, the truth is most prefer coins to possess their natural color.
Make sure your coins have been cleared of all dirt, debris and other objects prior to visiting the kiosk to ensure a successful transaction. Items like food, screws, dirty or sticky coins and other objects will jam the machine.
Wet the affected coin with clean tap or distilled water, roll in baking soda, then gently scrub with a soft toothbrush. Rinse the baking soda and debris off with more clean water, and repeat the steps if necessary.
Brasso is a metal cleaner that some people will already have on hand for other home applications and it is definitely the quickest and easiest method to clean pennies.
However coins will often have on them built up dirt and grease. This may get into the nooks and crannies of the coin. To remove this type of build up you can use a weak detergent solution with a soft cloth (Clux Wipe or similar will do the trick) to take this material off.
Use Hand Sanitizer
This buildup causes the metal to tarnish and can increase the amount of wear and corrosion on the face of the coin. The more the face of the coin is handled, the more subdued the features will become. Hand sanitizer will remove the bulk of those troublesome oils.
Due to its mild abrasiveness, it removes stuck-on particles and will polish most hard substances, including coins. You can clean most coins using baking soda and water alone; however, you should note that cleaning old coins may decrease their value.
Although nail polish remover does contain acetone, it also contains perfumes and is diluted to the point that it will not work on your coins. The additives will damage the coin's surface.
The oil-base makes WD-40 reasonably effective at removing it without a lot of work. There is of course some sacrifice when this stuff is removed but fortunately the metal underneath is in pretty good condition and the coin, in hand, is much more presentable.