I have had this coin for a while now, when I got it the listing pictures didn't show the fingerprints on the reverse. The obverse is perfect. The hazy areas really look like fingerprints, I tried gently rubbing with cotton swab and they won't come off, is it too late to remove them without damage?
Rubbing a proof coin with anything to remove fingerprints is the worst thing you can do. Waiting too long to try to remove fingerprints is not good, either, because the prints will eventually etch into the surface of the coin. However, you have no way of knowing how long the prints were on the coin before you purchased it. Maybe you should have returned it as soon as you got it. ~ Chris
Yeah... Sadly they are likely etched into the surface like Chris said. I put together an Ike dollar set almost thirty years ago and was not the careful numismatist that I am now. I have big ugly fingerprints solidly etched into the proof dollars. I washed in acetone with absolutely no change. I looked closely through a strong loupe and they were indeed etched into the surfaces.
Possibly a better choice I use is ammonia 1:1 with water and tamp with Q-tip then rinse with mild soap and water thoroughly. Acetone will only work on recently deposited skin oils or fingerprints and not the subsequent metal oxidation.
The only way it can be removed is with a dip. Yes it will affect your surface, but dilute the dip 1:10 or 1:20 with water and watch it very carefully . When the print is diminished 'passablely" to you stop and rinse well and then use acetone to remove any microscopic water. Contrary to many thoughts, this is not caused by the oils on the skin, but the sweat pores of the skin which causes the chemical reactions. This reaction will probably be visible no matter what is done, so do not do anything if you can't accept that. Better then to sell and buy another. IMO, Jim
I'm not sure if that is correct as the explanation has been that the oils are acted on by bacteria and generate organic acids that etch the coin. A dip is applying acid to acid to essentially burn off the oxide by oxidizing it further. The ammonia will neutralize the oxidation reaction and should be tried IMO prior to going to a stronger acid. Skin moisture will dry out & interestingly is slightly "basic" (greater than pH 7.0).
The palmar side of the hand ( including the area of the fingerprint) and the soles of the foot are the only areas of the human body besides the lips some external sex organ areas , that do not have oil glands. They do have sweat glands on the ridges of the epidermic ( fingerprints) and toe prints. Some feel it is adaptation to 'tool' using. I did mention diluting the dip by a factor of 90% or 95% water which makes for a slow controllable reaction I think. IMO, Jim
Actually there ARE sebaceous glands on fingers, and fats/fatty acids are in the residual of a fingerprint (as well as salts and amino acids and of course water). If you'd said hair follicles, that would have been correct as there are none normally.
Perhaps you are confusing the names. Sebaceous glands are sebum ( oil) producing glands and are attached to the follicle of hairs Sudoriferous glands are sweat glands and produce the salty acidic solution. They are on the ridges of fingerprints, not the sebaceous glands.
Actually I am not, and did alright in medical school. There are indeed sebaceous glands irregularly spaced in the finger tips. So, no, I am not confused (and rather disappointed by your choice of words in this regard); they are NOT necessarily associated with hair follicles. Nomenclature varies as far as the term "sudoriferous". Bottom line, there are fatty secretions as well as the other components listed in the residua of fingerprints - and this was my point as it is the former that are acted on by bacteria that then produce acidic byproducts that oxidize coin surfaces.
He's correct, dip is the only way you can get them off. But simply buying another coin to replace that one is the best idea.
