Acetone/Vinegar

Acetone is an organic solvent, incapable of reacting with silver but there's a remote possibility of reaction with copper. It's only good for removing organic stuff like glue.

Vinegar, on the other hand, is an acid. The Buffs sjh241 speaks of are showing dates because the acid has eaten the metal away, and the locally-stronger metal of the date is dissolving more slowly than the field around it. Consider that when you think about using vinegar to clean stuff off of a coin.

I know cleaning coins is taboo but I saw somewhere that acetone was the only way the pro's restored coins. So I tried it on a large 1844 copper penny token that appeared to have black soil or grime ground into the finest details. I won the coin for like $2 on ebay, probably because it looked low grade due to all the grime. So what did I have to lose?

Using swabs and acetone I meticulously worked the crud out from in between the finer lines in the design. I was pleased when the coin that appeared VG/F ended up looking EF to AU.. It did lighten the coin very slightly, originally the crud made it look as dark as an Oreo cookie. After the cleaning it ended up looking a deep dark bronze with some toning and just a hint of luster.

Vinegar or any other acid like lemon juice are NOT recommended for cleaning collectible coins. It is more used for coins that have been dug up after being buried in dirt for years and are encased in hard crud or are corroded beyond recognition. So it is more of a last ditch effort at identifying an otherwise unidentifiable coin. I also metal detect and vinegar, olive oil, lemon juice, peroxide, etc. are commonly used to help identify finds. Just remember if you go this route only treat coins of the same composition in the same solution. The acid removes some of the outer surface and it sticks to other coins. Kind of like washing bright colors with whites.

As I have said before, I dont like using vinegar since it eats away the entire coin. I much prefer using nic a date as you only treat the date area, not the entire coin.

Olive oil is a very mild acid. Its mild enough that it doesn't completely mess up copper, so works for old pennies.

It always kind of amuses me that the same folks that have heart attacks about dipping a coin for a matter of seconds dont have issues with leaving a coin to soak for days in acid (yes, I DO realize the difference in strength). Just sayin. ;)

I've used olive oil on a few old pennies found while CRH that were beyond identification. I used it just to test the technique, and curb my curiosity about what was underneath. I get mixed results with the oil, and I find I have to leave it for a very long time to get results.
The vinegar for me works fine for this experiment. Personally, I'd rather see the date and have the coin with an even tone than nic-a-date which highlights the area around the date and leaves the rest of the coin looking as it was. Reminds me of that look when you wipe a spot in a steamed mirror.
I just took a look at the Buffalo's in the vinegar as I flipped them today and can see if there are mintmarks. I just pulled an S, flipped it, and it's 1914.

sjh241.....are the buffs showing pitting from the vinegar ?

sjh, I see your point, and it does make that spot glare at you. But I still prefer that over the whole coin thing. But then, it just that, a personal preference. Look forward to seeing how they turn out.

Yea, good idea Carl! There are hundreds of such threads here on CC.

Instead of competely ruining a dateless buffalo by soaking it in vinegar for days, go buy yourself some muriatic acid from the hardware store. Apply a small drop to the date area, wait a few minutes and rinse it off. It's quite cheap, simple and 1000x faster.