Rubbing Alcohol To Clean Thumbprints?

The alcohol I have is 91%, but I guess even the remaining 9% water would be bad.

I've used rubbing alcohol as a substitute for acetone to remove PVC residue. It can leave spots. It can also effect luster and spark corrosion If a coin is soaked too long.

I think anything alcohol removes would also be similarly by acetone.
Neither of which should remove real toning, which are oxides/sulphides of metal.

Thanks Carl.
I went ahead and used it anyway. I picked up the bottle of 91% alcohol at my local CVS, actually. I used a lint free cloth and dabbed lightly at it and it came right off. Under 10x magnification I can see no scratch marks in that area. I guess for gentle spot cleaning for obvious dirt it works pretty well. I checked it again just now and see no evidence of water spots or anything like that.

You can get it at any hardware store. Make sure it's 100% acetone, though. Nail polish remover has some other chemicals thrown in there that might destroy the surface of the coin. I don't guess you guys have Home Depot over in the UK?

Acetone is an organic solvent(VOC) and will not react with metal as long as it is pure. It will remove things like PVC residue, finger grease, dirt, etc. It will not remove luster or toning. It is best to dunk the coin in the acetone so all sides are covered. You can let it soak for an hour or so if it is especially gunky, otherwise a minute or two is fine. Once you remove it from the soak, dunk it in a batch of clean acetone to remove anything dissolved in the soak. I personally see no need to rinse with distilled water since acetone will completely flash off and leave no residue.

Acetone will only remove recent fingerprints. Skin oils are acidic in nature and the prints will eventually be etched into the surface of the coin- acetone will not remove these prints. Another thing to note is that it is possible for the coin to have a different patina underneath what you may be removing, especially if you have heavy buildup around devices. It has to be a personal decision on what to do in an instance like this and ask the question- "do you have a really good shot at improving the coin?" If you answer no or are not sure, it is best to just leave it alone.

Disclaimer:Take precautions when using VOCs(volatile organic chemicals) on coins- do an evaporation test in clear glass for purity(if no residue left behind, it is pure enough to use), use in a well ventilated area(vapors can be intoxicating and not in a good way), do not use anywhere near an ignition source(either flame or electrical), and minimize skin contact with VOCs((minimal contact is acceptable, just don't bathe in the stuff)

Remember when purchasing Acetone from a hardware or paint store. I will usually come in a can. These cans are mass produced and are coated on the inside with substances that will normally not mix with the solutions inside. However, as in any mass produced manufacturing process, things can and do go wrong. If the inside of the can's protective material is not made just right, not coated properly, or it the container itself didn't seal correctly, the solution inside could be contaminated. Prior to using Acetone or similar products do as biochemist6 has noted. Note also, use only clean glass containers and glass utinsils when working with Acetone. Do not place in plastic or metallic containers when attempting to do anything with coins. Use in a well ventilated area. Do not smoke or light matches or lighters in the area.
Also, remember that if going out to purchase such materials for cleaning a coin. The cost of driving somewhere, the cost of the product, you time, possibly purchasing glass utinsils. If the coins in question are just normal, everyday coins, sort of a waste of money. However, on the brighter side you can then post a subject on how I spent my afternoon.