Let's discuss fingerprints

laurentyvan · October 11, 2004 1:00AM

The bane of the coin collector... fingerprints.

I've got several nice but relatively inexpensive silver and/or proof coins with slight evidence of fingerprints. I've read here that a recent (?) fingerprint can be removed with acetone-Is this true? Do any of you have fingerprint removal secrets you'd like to share? I use acetone or
MS70 for haze removal now-has it worked for you on fingerprints?

Also, an update on removing green gunk from coppers: olive oil is what I want to try-what else is suggested?

ajaan · October 11, 2004 1:07AM

Fingerprints? You mean like these?

On some coins they show originality. Obviously this coin was never cleaned or dipped. On an expensive coin I don't think it is worth the chance of removing them. You may ruin the coin. On cheaper coins I don't know.

AuldFartte · October 11, 2004 1:08AM

I use Xylol (generic = xylene) to remove the green gunk from coppers. Works well using a SOFT camel hair artist's brush in a mild circular motion when the coin is totally wet. Sometimes it takes several "baths" to get it all off. It will not remove corrosion, though. Acetone has not worked as well for me.

Recent fingerprints might come off the same way, but I have never had luck with them. I can't find the thread from the liteside about removal of fingerprints by "dipping", but I wouldn't do that to copper either. It will work on silver sometimes. The product I've seen is called "e-Z-est Coin Cleaner".

MacCrimmon · October 11, 2004 1:39AM

What Auld Fartte said.

Speaking of FPs.....I went ahead and bought (normally, I won't even mess with buying any coin with distractions) the most beautiful 1933 5 rappen Swiss specimen about 6 months ago because the mirrors were the blackest, deepest imaginable. Nice Cameo too.......except it had a light FP on the obv. behind the head!!!!

I hoped it was a recent oily patch and could be removed, but alas, there is the faintest evidence of the "unkind" touch....... Without the FP, this would have been a SP68 or the holy grail of SP69, but sadly it's only an SP66 according to the pros at Newport Beach.

DeutscherGeist · May 16, 2013 7:26AM

Just like the original poster, I have some silver coins, both proof and mint state that have some fingerprints on them. Acetone dipping is safe for coins, I understand, and it does a good job of taking off PVC, but not fingerprints (unless its very recent, then I am sure it will do the job).

An acid dip will take off fingerprints, but that will lower the value of the coin too. So, that is not even worthwhile to try. Acid dip is forbidden. No exceptions.

I was wondering if one used a sonic cleaner that jeweler's use. The solution poured in could be 100% acetone. Any luck with this technique? I will buy a sonic cleaner if I know it will help me. Basically, I the sonic cleaner uses sound waves to loosen stuff on the coin. It will not dent or scratch the coin since nothing is really touching it.

What I am learning here on the boards is that it is best to stay away from coins that have fingerprints. We do not know if it was recent or not. Better not bother with it. The silver coins in question are not too many and they aren't worth a fortune, but I still like to have a pristine collection as much as possible. If worse comes to worse, I guess one can keep the coins as they complete a certain set, but with the knowledge that the value is just not as high. Like most things in life, we learn to live with flaws, but it does not mean we do not have a fabulous collection in its own right.

pruebas · May 16, 2013 7:49AM

I doubt an ultrasonic cleaner will remove fingerprints. Once they have been on the coin for a while, they are etched into the metal, and nothing short of acid (as you mention, but I have never tried) will remove them. If acetone doesn't do the job, then it's too late.

Sometimes you cannot help buying a coin with fingerprints. I have a few very rare (R7-R8) pieces with fingerprints. One is even in a PCGS PF65 old green tag slab. Where would I ever find another?

coinkat · May 16, 2013 8:28AM

fingerprints do not mean the world is coming to an end- they can be a pain, but in some instances they are overblown

DeutscherGeist · May 16, 2013 10:17AM

Pruebas,

Old or rare coins, I understand, but newer coins of the past few years is what I am referring to. Its annoying to have fingerprints on silver Philharmonics for example. That coin has only begun in 2008.

Gazza · May 18, 2013 3:19AM

By the time a finger print becomes visible the damage is done.

Sapyx · May 18, 2013 7:17PM

Yep. If you touch a coin with your bare hands (or you see one of your coins being touched by someone else) in such a way that you know a fingerprint will develop if you do nothing, you can wash the fingerprint oils off with acetone and no print will develop. But once it's been left there long enough for you to see a dark-coloured fingerprint, then it's too late.

Fingerprints on coins are caused by the salts and sulfur-containing oils in the sweat on your fingers. This reacts chemically with the metal of the coin's surface by much the same chemical reactions that cause "normal" toning and tarnish. Such chemical reaction byproducts are not removed by organic solvents like acetone, nor are they affected by ultrasonic cleaning.

LochNESS · May 21, 2013 3:14PM

Sometimes, when viewing my rare coins that have FPs, part of me wants to find their owner and serve them a beating

As with scratches and dings and plain-Jane-wear, you learn to look past them.

This is my favorite FP'ed coin, mintage 700:

daOnlyBG · May 22, 2013 1:30AM

So, here's the deal with fingerprints: each time your fingers touch a coin, the oils from your fingers react with the coin's surface. Once they start that reaction, it's very difficult- if not impossible- to reverse that process. With silver, you can dip it in acetone just a minute after you touch the surface, and you'll probably get rid of the oil in time so that no fingerprints affect the coin. How long the time frame is between the moment you touch the coin's surface and when you dip it in acetone, I don't know. If you see a silver coin with fingerprints on it, you can still dip it in acetone, and you should for a couple reasons: (1) it takes the oil off, and the oil's effects on the coin would be visually minimized- that is, it would be difficult to see the affected area, even though it's still there, and (2) it keeps the toning due to fingerprints from spreading. That's probably the most important reason to give an acetone bath.

I have less experience with copper, but I do know a thing or two about copper and fingerprints...similarly with silver coins, the oil from your fingertips will start a chemical reaction with the surface of the copper coin, only with copper coins, the reaction time is much shorter. That's why it's so important to handle these coins around the rims. If you see a copper coin with finger prints on it, chances are it's too late to get rid of those fingerprints- but it's never too late to keep the oils from spreading. However, I wouldn't dip copper in acetone- there's a pretty weird "green effect" that develops on them. You can ask someone for a recommendation on a good solvent to dip copper in (as opposed to abrasives, i.e., acid).

Let's discuss fingerprints

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