To start off, I know you should never clean coins, escpecially any with any value over the face. I am new to coin collecting, so here are a couple of scenarios where I'm wondering what the opinion of light cleaning is. I have 100's of the following, averaging XF condition. 1. Mercury and roosevelt silver Dimes (non key dates, XF) 2. Washington silver quarters (non key dates, XF/AU) 3. Standing Liberty quarters and washington quarters (found in the lake, terribly corroded). The dimes and washington quarters are just dirty. I don't mean toning, or naturally occuring corrosion. I mean, they are just dirty from some foreign substances, gum/glue residue, and who knows what. Is there any reason I shouldnt clean these with a non abrasive soap cleaner and water to try remove the dirt buildup? If I do that, will someone in 50 years look at these coins and say "oh man, these were cleaned!"? Is there any hope for the liberty quarters? They have probably been in the fresh water lake for over 50 years. They are almost all black. The only thing I can tell is that they are liberty quarters, otherwise no writing is legible. Cant see the dates. Any suggestions? I guess the main question is: What is really the definition of 'cleaning' when it comes to coins? Does cleaning really only reference the use of chemicals or machinery? Or does breathing on it/or using water and wiping it with a cloth also considered cleaning? Thanks for any insight.
my definition of cleaning is using something abrasive on the coin that takes off orig. medal. and using chemicals in an attempt to enhance appearence/decive. putting coins in distiled water to try to get some dirt off is perfectly acceptable to me -Russ
Conservation (market acceptable) - Using techniques to enhance appearance without damaging the surface. Cleaning (unacceptable) - Using techniques that permanently damage the surface; therefore, significantly reducing the numismatic value. Once you cross the line from conservation to cleaning there is no turning back. Always following the solvent polarity ladder when attempting conservation: 1) deionized water 2) acetone 3) xylene This range covers from polar to non-polar and should remove most surface debris. Sometimes reversing the process (i.e. starting with xylene) proves successful too. For an amateur, going beyond soaking in these solvents is "dangerous" and will likely result in a cleaning.
I buy bags of silver coins from time to time. Nothing in them worth more than spot (no numismatic value). I usually dump them in a plastic dishpan with warm water and some soft soap or other liquid soap. hand washed and rinsed, they are dried on a cotton bath towel. Once dry, they then get sorted by decaded and rolled up in clear plastic coin rolls.
There is a reason one should never use soap/detergent to clean coins. It's because it is all but impossible to rinse all the soap off the coins. There is always a residue from the soap left on the coins and over time it will have a detrimental effect on the coins. And you can call cleaning conservation if you like, but that too can lead to problems. For not all forms of conservation are harmless to the coin. It is far better, at least in my opinion, to use the terms harsh cleaning and cleaning. That at least clearly differentiates one from the other. Cleaning never harms or alters the surface of the coin. Harsh cleaning always harms or alters the surface of the coin. And even using chemical dips can be harsh cleaning. Dip a coin 1 too many times or for too long of a period and the coin is irreparably harmed. Even using the solvents that Thad recommends, if not done correctly, the coin be harmed by using them.
Sure, coin dips are deemed acceptable, as are the solvents that Thad mentioned. But they must be used properly or as I said, even they will not be acceptable. Soaking in distilled water is also acceptable. But that's pretty much it. There are some proprietary chemicals that are also acceptable if properly used, like Thad's Verdigone. And the stuff that NCS uses (but nobody knows what those chemicals are). And there are methods used by professional conservators to clean coins recovered from the sea or the ground. But even those are detectable in most cases and thus the coin is forever labeled as harshly cleaned. There are literally thousands of different ways that people use to attempt to clean coins. But if they involve rubbing or wiping or even touching the surface of the coin then they are not deemed acceptable for they will leave traces that can be seen by an experienced eye. And don't think that just because you can't see them that they aren't there - they are.
