While learning to clean old coins, you should experiment with different techniques to find a method that works best.
As you begin to clean ancient coins, experiment to find methods that work best for you. It will probably take a while to get the process right. The first coins that you clean should be coins that you don't mind ruining. This is part of the learning process.
When cleaning an ancient coin, patience is the key. Work as gently as you can. You goal is to remove dirt and encrustation without damaging the surface of the coin, or the coin's patina (a thin, greenish film of corrosion that can build up on oxidized areas of a coin).
There are a variety of tools that you can use to clean a coin. They range from liquid soaks, to tools that you can make at home, to manufactures brushes of various sizes, to brass tools. When it comes to protecting your coin during cleaning, plastic and wooden tools are best. When a metal tool must be used, use brass, because it is a soft metal. Something to remember about metal tools: never use a metal that is harder than your coin. For example, never apply a steel tool directly to the surface of a coin.
Dental tools, toothpicks, tooth brushes, and straight pins make good tools for cleaning coins. A trip to a hobby store can score you a set of brass tools. Strips of brass can be found at metal supply and hardware stores. You can shave and file these into points and edges that can bed used to get into those tight areas between designs and inscriptions.
When you are ready to work, set up a clean and spacious work area with good lighting. Have on hand a supply of water for rinsing. Before cleaning a coin, submerge it in liquid to soften the encrustation on it's surface. In some cases, you may find that soaking alone cleans a coin. Wiping it with a soft rag after you remove it from the soak may be all that you need to restore some of the coin's original beauty. Distilled water, lemon juice, calgon water softener, vinegar, baking soda, and olive oil are surprisingly useful. These methods can remove dirt slowly, and you may have to soak a coin anywhere from a few hours, to a few weeks. To remove olive oil residue from a coin, soak it in Tri-Sodium Phosphate, TSP can be found at paint shops, and home repair stores. Other metal degreasers can be used, but remember to test new substances out on your least valuable coins before applying them to your most valuable coins.
After you have soaked and rinsed your coin in fresh water, gently work with your brushes and small detail tools to clear remaining dirt and encrustation from the surface. If some spots are not lifting, repeat your soaking techniques. If these problem areas still persist, do not try to force them off with a tool. It is better to leave a coin as it is, than to damage it by force.
After you have cleaned your coins, you may want to apply a coin sealer, or a wax polish to preserve the job that you've done. Check the usage labels on these products to make sure that they are compatible with your coins. Look for these supplies in numismatic supply stores, internet stores, or mail order catalogs.
You can find more information here:
http://www.tradingideas4you.com/fun-entertainment/hobbies/hobbies.html
