How to remove dark patina/corrosion/??? From Buffalo nickels?

I have a couple better date Buffalo nickels that are just about as far gone brown as any I’ve seen. Is there anything I can do to bring them back to somewhat of a presentable state? I have tried acetone to no avail.
Thanks!

 

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That coin is toast from environmental damage.

 

Both coins look circulated. Not sure what can be done without them having an over done cleaning look.

 

Yeah, the vinegar method leaves them dry and pitted…it’s. Shame about the 13S because it is only lightly circulated…probably low XF but the corrosion is a killer

 

Real shame about that 13-S T2. I would leave these coins alone. I can't see any attempt to "improve" them making them any better, but maybe someone here knows more than I do.

 

You can make them shine but that just detracts from and hurts the coin. Best to leave them be.

 

They are what they are. Maybe hitting the 13-s with verdicare would be beneficial because there appears to be a little bit of verdigris forming on the obverse, and most obviously between the E and S of 'States' on the reverse. That would be more about preventing further decay, rather than repair.

 

Distilled water soak first, give them a few days, and follow with a wet Qtip roll following the metal movement,
Post a few Pics and let us know how they turned out.

 

Looks like there are some unpleasant surface defects under the oxidation. You may want to try immersion in diluted ammonia, not vinegar (base not acid). I don't think you have a lot to lose in that direction....You can experiment with ordinary Jeff nickels just to see (try to get the unscented or dyed ammonia).

 

Vinegar is harsh, and should never be done to a Buffalo, You are removing numismatic value every time you do it.

 

Ammonia is no different.

 

Actually it is
See your chemistry book
I also said DILUTE

I also said to get a feel for it’s use on ordinary nickels as composition of alloy obviously similar.

I might also recommend Weimar White “Coin Chemistry” book (I believe that’s the name)

 

This is an example of how a copper-nickel coin corrodes. There is not much you can do to restore it.

 

Now that is true - what is gone is gone. Interesting read if you are nerdy enough (might be me on occasion) but study up on reduction reactions in chemistry - the opposite of oxidation.

 

I think johnmilton is correct. Nickel oxide has 2 major forms of oxide. One follows the normally expected chemical oxidation and is Ni(II)Oxide and is green NiO. This is not copper verdigris and is normal oxidation in open atmosphere. If the Nickel atoms are exposed to reduced oxidation ( low oxygen availability ) a chemical oddity develops which is Ni(III)Oxide and is black Ni2O3 which is not common as it requires specific conditions over a period of time with low oxidation. I would just leave it as it is , unless you are a chemist familiar with stoichiometry techniques and have the lab equipment. Jim

 

Aside from loosing value, a quick dip might do it, but if you really like the coin, pay for one of the TPG to conserve it (read as "clean it"). It would be a good test of their abilities.

 

You might try an ultrasonic cleaner with a water/Dawn solution. And, in extremis, you might blast them using ground walnut shells. That last will probably get me flamed. But, you know, they are pretty far gone with corrosion and the 17-S has significant impact damage. If you just want them to look better in your own eyes and are not concerned about what somebody else thinks, then you can do things that might be otherwise be frowned upon.

 

There are many easily obtainable oxidizing agents, but not many common reducing agents. I always wanted to mess around using sodium sulfite solution which can be oxidized to sodium sulfate and reducing the "other guy".

 

I believe that catalysts will perform that function and that electrolytic principles involved but have forgotten that bit of chemistry from over FORTY years ago. That is what the aluminum foil with baking soda +/- vinegar does.
I used to experiment with a 9v battery and this produced some very good results on coin surfaces but early on had some issues and then other life issues distracted...

 

These are some great ideas about restoring a corroded coin, but you can’t replace the metal that has been damaged. You can only find better ways to remove it. You are still left with damaged surfaces.