Cleaning Copper Coins - Tutorial, page 1
Simplified and Quick Method for Cleaning Copper, Bronze, & Brass Coins & Enhancing Their Appearance
This simplified method applies to the dug copper, bronze and brass coins that are not worn out and not of a high value - they are neither key-dated nor extremely rare. (Highly valued coins should not be touched at all!)
This method is useful when you just want to make your coin finds look presentable, i.e. their coin designs are enhanced and well visible, and do it quick so you can take their pictures to be posted in your favorite metal detecting forum or blog on the same day you dug up the coins.
If your goal is just to enhance the coin's features, you do not have to weigh the exact amounts of participating chemical reagents, or to follow the exact procedures of artificial coin patination as the professionals do. Nevertheless, the simplicity of this method does not imply the lack of your control over the process. Please make sure you know what you are doing and follow these steps:
1) Soak Coins Before Cleaning
Soaking of the newly dug coins is done in warm soapy water. Liquid soap or detergent help loose and lift the dirt off the coin's surface without doing anything to the coin itself.
2) Scrub Copper Coins with a Toothbrush and Toothpaste
Rinse the coins with water after soaking and then wet-brush them with a toothbrush and toothpaste, so each coin would not have anything but a layer of oxidized coin metal - the patina, on its surface. Make sure the toothbrush does not leave scratch traces on the coin's surface in case loose stone particles are still present on the coin.
You may also rub wet copper coins with the fingers, using fine household salt (NaCl), sprinkled on most easily from a salt shaker. The nature of salt's action is much more mechanical than chemical because salt can penetrate especially into the corners of the elevated coin features or into their depressions.