Blue Ribbon , I know alot "coin guys" who swear by it. Do a search for blue ribbon online. I have seen it on E-bay & stuff too. It works well for the coppers that are drying out in the air. It kinda seals it keeps it from flaking....& it gives a nice patina...not a black stain like olive oil does.
were tt buy http://store.royreynoldscoins.com/blricoco.html
CLEANING COPPER COINS
Copper is among the most chemically active of all coinage metals. When a copper coin is first struck it has a brilliant pale orange surface and turns brown when circulated.
Copper coins tend to look worse after being cleaned and are more easily ruined than gold or silver coins. When absolutely necessary, clean dirty, green crusted, badly corroded copper coins without scrubbing them. Try soaking them in grape oil (or olive oil if grape oil is not available).
Some results can be obtained in one to four days, but don't be afraid to wait several weeks, months, or even a year for desired results. Remember, some of the green patina may be desirable in a copper coin. Although not so much a problem in Colorado, the prudent collector in a humid climate does not collect red copper coins which oxidize badly. Even in Colorado, it is wise to keep a desiccant in proximity to brown copper coins to absorb air moisture. Every six months, check your copper coins and stroke them with a soft camel's hair brush, such as is used on photographic lenses.
Another way to clean copper coins, use a product (available from any good coin supplier) called MS70. Use rubber gloves, this stuff will dry out your skin. It is safe, but if whatever is on the coin is stubborn, the coin can be soaked for days and even weeks in the MS70. You may use a soft toothbrush that will not harm the coins surfaces to remove the dirt in the devices and continue soaking. When you are satisfied with the coin's appearance, neutralize the MS70 from the coin with baking soda and warm running water. Dry the coin thoroughly and then apply a coat of Blue Ribbon coin cleaner and preservative, and let it dry for several days (or as long as it takes). Wipe any excess off with soft cotton balls, and store in safe cardboard 2 x 2's with the clear centers (use the ones that staple shut, not the self stick, that glue dries out and may not be safe). Make sure that the supplier tells you that the 2 x 2's you bought from him are safe. If the coin is somewhat discolored, you can use Dellar's Darkener after the soaking in MS70. Wipe any excess off and let it dry for days, or as long as it takes so that no more can be removed from the coin with a cotton ball. Use this before the Blue Ribbon until the coin is satisfactory to you. The Blue Ribbon is a cleaner also, and may remove some of the darkener, but the end result will be a beautifully clean and conserved coin for your collection.
