To clean coins is not recommended, but if you really feel you must be cleaning your coins, follow the steps described below to minimize the risk of damaging them. Never use metal polish to clean your coins!
About the only time I can think of when you would normally want to clean coins would be if you wanted to help a youngster begin a coin collection from circulating coins. Circulating coins can be filthy and carry germs, and this is theonly instance in which an amateur should clean coins.
Never clean old coins you have found or inherited!
Time Required: About 10 - 15 minutes to clean a batch of 30 coins
Wash your hands with soap.
Washing up will remove the oils and tiny grit from your fingers.
Lay down a soft towel.
Place a soft cloth or towel, folded over a couple of times, on your working surface to catch coins you might drop, and to provide a space for them to dry.
Set up your soapy bath.
Fill a small plastic container with warm tap water. Do not use glass, china, or metal, as these hard surfaces can scratch your coins! Disposable food storage containers are perfect for this. Just don't store your coins in them permanently. Add a small amout of mild dish-washing detergent to the container filled with warm water. Don't overdo it - all you need is a really tiny squirt.
Prepare your final rinse bath.
Fill a second plastic container with distilled water, for the final rinse. Although distilled water is by far the best, you can substitute hot running tap water.
Clean the coin.
Pick up the first coin, and immerse it in the soapy water. Gently rub both sides of the coin between your fingers, paying attention to any stickiness or gunk. Rub gunk near the edges away from the center of the coin, not into it. Always work in an outward pattern. Dirt and gunk near the edges should simply be made to go over the side with your thumb, not all the way across the coin. Don't put all of your coins in the water at once! Do them one at a time, to avoid their coming in contact with each other and causing scratch marks on the surfaces.
Rinse the coin.
Rinse the coin under running water, gently rubbing until all soap residue is gone. Always remember, gentleness is the key! Don't rub hard, and if you feel any grit, even light grit, don't rub it into the coin because it will scratch the coin very easily. Instead, sort of agitate the coin by moving it quickly in the water to dislodge the grit, touch it gently only if needed to free it up.
Every motion you make with your fingers should be focused on not causing scratches to the coin's surface.
Do the finishing rinse.
Swish the coin around in the distilled water, to remove the chlorine residue and other contaminants that are found in tap water. Hold it by the edges and agitate gently. At this point, you should no longer touch the coin on its faces. Touch it only by the edges when using your bare fingers.
If you must use tap water for the final rinse, then run the coin under fairly hot water.
Allow the coin to dry.
If you use a distilled water rinse, you can set the coin on the towel to air dry. The coin should dry spot-free, because distilled water is free of dissolved minerals and other impurities.
If you had to do the final rinse in hot tap water, then gently pat the coin dry to help prevent spotting. Never rub a coin dry! Always pat it dry gently with a soft cloth or tissue.
Repeat until finished.
Now wash the rest of your coins, one at a time, following Steps 5 through 8 carefully. If you run across a coin that needs to soak for awhile to get clean, put it in the tub of water off to the side, so you don't accidentally ding it with another coin you are working on.
Store your coins.
Make sure your coins are absolutely dry before putting them away. Damp coins can suffer damage over time. Remember to always handle coins only by the edges. The only coins I ever touch the faces on are the ones I am about to spend! :)
Never try to remove the natural oxidation from coins, such as the tarnish on silver. This is called "toning" and the coin is worth more with it intact. Removing it will damage the coin's surface and greatly reduce its value. In other words, no dipping, polishing, or chemical solutions should ever be used on coins.
What You Need:
Two small plastic containers
Mild dish detergent
A soft towel
Access to running tap water