I have a few gold coins I've collected over a bit, and some of them exhibit what looks like fingerprints or material on the coin. I've soaked them in acetone, thinking it was fingerprints or something, but with no success. I'm new to this, so I'm not sure what to attempt next. Help?
Well, there's certainly a fingerprint pattern on the K-Rand in the first picture, though I'm not sure what the contaminant on the surface is. This next is gonna sound strange, but have you heard of cyanoacrylate fuming? It's often called "Superglue fuming" and is used as a forensic method for detecting latent fingerprints. Those prints almost look like that. Mind you, I'm not suggesting they are residue of cyanoacrylate fuming - merely that they look like that. I know next to nothing of the process. Frankly, I'm surprised that acetone did not remove the prints. Would acetone remove cyanoacrylate glue? Is my whole discussion of cyanoacrylate a red herring? Maybe. Anyway, there must surely be some kind of solvent that could remove that, but I don't know what to recommend. Are you keeping these as bullion?
Yes, it definitely would. In another life, I used acetone to remove cyanoacrylate glue from fingernails.
Acetone will only remove fingerprints from coins when the fingerprints are fresh. Once the prints have been there on the coin for a week or so acetone won't take them off because the acid in human body oils physically etches the metal of the coin making the prints permanent. Well, semi-permanent anyway. I say that because using a coin dip, (which contains an even stronger acid), will remove them. So if ya wanna get the prints off your coins you're have to dip them. But I strongly suggest that you have someone else who knows what they are doing dip them for you.
