I know you should always hold a coin by it's edge. But...why do sometimes fingerprints show up on a coin, and sometimes they don't? Let's consider this. I have a quarter from 1853, It probably circulated about 30-40 years. In that time frame, it was touched, by human hands, hundreds of times. Now 159 years later, it sits on my desk. There is not one finger print on it. So, considering it's be handled that long, why hasn't it a print on it? I know proof coins, and freshly minted, red coins, will print. So....are older coins, well circulated, safe to handle without holding the edge?
You know you are not going to pay attention to anyone's answers, so why do you keep asking questions?
I'm not a chemist but, I would think, that metal that old would have so much wear and contamination that it would all blend together. It's one big fingerprint. The same way you do not see prints on brown cents. Sound like a good reason to me.
Newer coins, cleaned coins, dipped coins, proofs, have fragile surfaces , usually with little patina from copper oxides and copper sulfides, or silver if that is the metal of the coin. Older coins have had time to build a patina, and if circulated to even wear any earlry prints off. Also washing the hands many times a day loosen the pore "plugs" and allows more sweat and oil to escape, whereas in long gone days, handwashing was less frequent, so maybe that is also a part of the problem.
