Cleaning silver coins

Let me start by saying this: If you buy uncleaned coins, you will have very, VERY few chances to clean high grade silver coins. You may find the occasional silver coin, but, as I've mentioned before, they are fairly scarce in the lots that you find on eBay or Yahoo.

Remember that silver that is exposed to the sulpher found in the atmosphere will develop a gray to black tarnish because of the oxidation that naturally occurs. This toning is usually desirable in ancient coins, and unless it is very thick and detracts from the appearance of the coin, should be left in place. Toned coins are more attractive (in the opinion of many collectors) than bright, shiny coins.

My Disclaimer: Unless you are an experienced "cleaner", don't attempt clean higher grade silver coins, unless you are willing to take the chance on ruining (thats right....ruining) them.

With that out of the way, lets begin.

I always recommend starting with the most gentle method of cleaning, which is careful brushing with a soft toothbrush. This will remove any loose dirt. This can be followed with soaking in distilled water for a day or two, followed by more brushing. Always proceed s-l-o-w-l-y. Return the coin to the distilled water and soak them for a few more days. Continue this until you have removed as much of the dirt as you can. Silver coins with a light coating of dirt will respond well to this method, and it is the least destructive to the coin.

NOTE: Do not soak bronze and silver coins in the same distilled water. Chemical reactions between the two metals can change the color of the silver.

If there is still hard packed dirt remaining in the details, you will have to decide if it is best to leave it in place, or to move on to the next step.

At this point, I will usually resort to the old standby....toss the coin in olive (or lanolin) oil, and leave it there for a couple of weeks. Take it out, brush it, and return it to the oil. Repeat this until you have removed as much of the dirt as possible. Rinse it well in a mild non-detergent dish soap mixed with distilled water to remove the remaining oil. Dry the coin by placing it on paper towels for several days.

Still not clean enough??

Remember where I talked about using CLR for spot cleaning those icky green areas of bronze coins? Don't use CLR on silver coins. Instead, use the same technique of soaking a toothpick in diluted lemon juice, and then dab it on the encrusted areas. Let it soak in for a few minutes, and then brush it off with distilled water. Repeat this as many times as needed. The mild acid in the lemon juice will help to soften the dirt, and make it easier to remove.

After using lemon juice, you will have to make sure that all of the acid is removed. Do this by soaking the coin for several weeks in distilled water, changing the water every day or two. Dry the coin as suggested above.

If there is still dirt hiding in the small details, you can remove it mechanically. I would STRONGLY recommend using a stereo microscope for this. Place the coin under the microscope. I usually have the scope set on high power (40x). I then use a sharpened bamboo sliver to carefully push the dirt out of the details. You will have to be careful, because silver is a very soft metal, and even a little slip will put a crease in your coin.

You can put the finishing touches on the coin by making a paste of baking soda and water (distilled, of course) and gently rubbing it in the palm of your hand.

Horn silver (silver chloride) may be present on some ancient coins, and is usually distinguished by a yellowish-silvery coating on the coin. It tends to smear when brushed, and usually detracts greatly from the appearance of the coin. It is VERY difficult to remove entirely, and often results in an ugly coin. If you simply must try to remove it, wrap the coin in aluminum foil, and place it in a shallow glass dish with a small amount of malt vinegar. Leave it in place for about a minute, remove it from the foil, and brush it off with distilled water. Repeat as needed. This process will cause the chlorine to be released from the horn silver, and may also leave strange looking deposits of silver on your coin. Use this technique (as all chemical/acid processes) with caution, and only on coins that you are willing to damage beyond all hope......