For the record, cleaning coins takes a lot of time and patience, but even more importantly it can be very costly, and the results cannot be guaranteed. Why? Because none of us can know the complete life history of a coin, we cannot easily determine the environments it has been exposed to (ie weather, chemicals, intentional change). And therefor we cannot accurately predict the results of cleaning the coin.
Coin collecting is a wonderful and fun experience that everyone should be able to enjoy. Here is how PCCS got its start. One day after sorting through an old bank bag of U.S. Wheatback Pennies, the tips of my fingers were very filthy: with a range of colors from green to black, YUCK! Whatever it was on those coins, was now all over my fingertips. That certainly is not patina, and I soon realized it was decades worth of oil from people's fingers, along with dirt and dust from hands and pockets (or just about anywhere a coin might be found). Something had to be done, so I began researching every technique available for cleaning coins, but always keeping in mind that I did not want to damage the coin but just make it look clean and desirable.
What good would we be if we didn't show you the results of our cleaning experiences...check out these real projects in-progress at PCCS.
Regardless of the opinions of others, an owner must decide for themselves if they would be happier with the coin as-is or with a properly cleaned coin.