Vinegar. A common ingredient in DIY eco-friendly cleaners, the acetic acid in white vinegar can help wear away the contamination on your coins. Soak your coins in a glass or other non-corrosive container for at least 30 minutes, up to overnight, and then wipe with a clean cloth or scrub gently with an old toothbrush.
Ultrasonic Cleaners
These coins are cleaned by using distilled water with a small amount of detergent in a special vibrating container. Acid based cleaners will eat away at a coin's surface diminishing its value.
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.
Vinegar and Salt
Mix vinegar with salt. Place pennies in the solution and let them sit for a while, and then use a clean, soft toothbrush to clean any dirty areas. Rinse the coins, and then polish them with baking soda paste.
Within about 30 seconds, the pennies in this bowl will start to shine. 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.
Soap and Water - This is generally the only way to clean silvered and silver-plated coins, without damaging the silver. Ammonium - Windex works fine. This will clean the coin without damaging the silver.
Put down the scrubber. It's never bath time for coins. No matter how dirty, worn or tarnished they are, the filth is part of their charm (aka value). Over time, coins go through a natural process called 'toning'.
In a plastic container like those for storing your leftover foods or a small child sized bucket, add 1 cup of white vinegar and soak 4-5 coins in it. The longer you leave them to soak, the better the effect of the vinegar will be. For coins that are more than 50% corroded, it's advisable to soak them overnight.
Cleaning an old coin would remove the patina or toning that helps make it even more unique and visually appealing. Removing this effect can significantly reduce the value of the item. The other main reason you shouldn't clean old coins is that you can easily damage them.
Add a small amount of water to a tablespoon of baking soda to form a paste. Apply the paste to each coin using an old toothbrush and scrub gently. Rinse the coins to reveal the now-shiny surfaces.
The abrasive product can leave scratches or hairlines on the coin, as well as destroy the luster of the coin; in many cases a coin that has lost its luster will rarely be worth more than half its original uncleaned value. 3. When a coin is cleaned, it takes on an unnatural color.
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.
How to easily clean your coins with CLR You can use a plastic cup for the container that you clean the coins in. Add 1/4 cup of CLR and 1/4 cup of water to the cup. Let the coin soak in the cup for about 30 minutes.
WD-40 is a lot less messy than olive oil but more expensive and not for use on the semi-industrial scale which some coin-cleaners seem to do. I would do 2-3 coins and leave them in the oil for a day or two at most (not being the patient type). It did help some on hard encrustations but not enormously.
The combination of vinegar (a weak solution of acetic acid), and table salt (sodium chloride) helps to dissolve the copper oxide, and also forms the blue copper(II) ion, which is soluble in water. The penny becomes shiny again!
Coins become dirty due to oxygen in the air reacting with the copper metal. This forms a dark layer known as copper oxide. Over time, the oxide layer increases and makes the coins darker. Vinegar is an acid which can dissolve the unwanted oxide layer, leaving a shiny surface.