Understanding Cleaning

Acetone is a non-oily quick drying solvent that works well on silver and gold coins. It does not leave a residue on coins, remove any metal and generally does not affect the ability to get a coin slabbed. Olive oil works best on copper coins. It is not very acidic and can, if the coin is left submerged long enough, remove verdigris and green oxidation safely from copper. I'm not sure how easily this is detected. I think it depends on the severity of the problem. I hope this helps and that others will offer more information. Mike

Both acetone and olive oil are really "conserving" rather than "cleaning" agents, in the sense that they remove things that are either physically obstructing the coin or things that, if left on the coin, will cause damage over time. Still, cleaning is cleaning, and best avoided unless a coin really, really needs it.

Acetone, being an organic solvent, is good at getting rid of "organic goo" - typically things like stickytape residue, coin album residue, paint, varnish and fingerprint oil. It will not remove oxidation, tarnish or toning. (incidentally, acetone should also be good at removing olive oil after you've finished treating it). Acetone works quick (you shouldn't need to soak a coin for more than an hour) but is both volatile (evaporates quickly) and flammable, so treat it as slightly more dangerous than gasoline.

Olive oil is a tried-and-true method for cleaning up a copper coin that's "gone bad". It's a favourite technique of detectorists and archaeologists. It's good for removing physical dirt (i.e. soil), particularly the hard concretions that can form after a century or more buried in the ground, and verdigris, the nasty powdery green stuff that can turn a copper coin into dust if left untreated.

It's very much a long-term treatment; the coins should soak for weeks or months, with regular changes of the oil. Distilled water is another alternative to olive oil, but thst takes even longer to work. If your coin doesn't have dirt or verdigris, there's not terribly much that olive oil will do for you.

Neither olive oil nor acetone are supposed to affect the natural toning or appearance of the coin.

In days gone by, collectors would "preserve" their copper coins, either with a nice thick coating of oil or a good coat of varnish. Coins so treated have for the most part maintained their condition, though they do tend to look "unnatural" compared with a raw copper coin.

I don't but that is a good idea CPChicago. I just purchased some olive oil and distilled water yesterday to try and clean some of my world coins as a test. I'll try and remember to keep an accurate records...though no promises.

I will try to do the same Madmartigan, but that would also require figuring out how to take nice, clear pictures of coins, which I have struggled with so far.

Thank you Sap for the information. I used the Acetone and it cleaned my coins nicely. I have a clearer view of the coins.

Still learning!

Now - I have beautiful pics of all of these coins and they are too big to down load. I may just have to buy a coin camera.

Olive oil is slightly acidic and promotes pitting/reveals hairlines. This may adversely affect silver coinage.
Silver=Acetone, Methanol, or Acetonitrile
Copper=Olive oil preferred by some b/c it leaves behind the aforementioned protective layer/film and Cu is more resistant to it's effects.

Which one would be good to remove the black residue the is always along the date, IGWT, Liberty, and the mint marks on copper? I just know that a couple coins I have are doubled but the black stuff is hiding it. I have been using witch hazel to clean them but it is not getting rid of the grim.

Never use Olive Oils on any coins. For one thing not all Olive Oils are the same. Like any product that is manufactured by different organizations, their methods of productions are different therefore the end results can vary dramatically. If you were succesful in removing anything with Olive Oil you now have a cleaned coin and it can be easily detected by any grading service. The removal of many contaminates on coins removed some of the metal of the coin and this is also detected. Then naturally there is the slimy leftover from the oil which now has to be removed with something like Acetone and then rinsed with distilled water. Now here is the problem with Acetone. Purity. If you purchase Acetone from the normal paint section of a store, you have no idea how long it has been there. Being a great solvent it may have alrady started to disolve some of the inner lining material from the can. The way to check for this is to put some on a clean glass dish and allow it to evaporate. If there is any residue at all, discard this Actone as contaminated. Many people have tried the Olive Oil treatments and have many different resolts due to different items in the so called purified or Virgin Olive Oils. Ever wonder about the different containers of Olive Oils? Some in cans, glass jars, plastic bottles, etc. And how long was that oil in that container? Be carefull using anything that people recommend on your coins. They are your coins and if things go badly, they are still your coins and not replaceable by the people that said to try this or that.
The thing to remember is not all subtances are the same even though they may have the same names. Sort of like not all vacuum cleaners are the same although they are all vacuum cleaners.