Coin Conservation

I would try acetone first.

Here is another one with a different type of damage and, I suspect, reqiring, different approaches:






Appreciate advice.

My guess is you're looking at coins which were victimized by Katrina or something similar. Your detail image of the reverse of the SLQ shows a "thickness" to the corrosion which I wouldn't expect to see it it were due to PVC. I have the sinking feeling these coins have been in contaminated salt water, and there's not going to be a whole lot you can do for them.

As regards acetone, if you want to give it a try (it won't hurt anything):

https://goccf.com/t/140721

That'll be a start.

SsuperDdave - thinks your procedures really help. Your before pictures appear to have only a little green. Mine are much heavier with the green. Sone of it even makes a powder. I put them in a roll and then took them out and a powder came out. They were in a baking powder can, buried for 70 years.

Anyone on the other contamination? I will also, post a dime from the find that is gold toned on the obverse and on the reverse - one tiny green spot.

Here's the dime.




Looking for experts!

The SLQ doesn't look like PVC, but the Dime could be. If that's PVC on the Quarter, it's destroyed. The coin I posted was definitely a PVC infestation; with your description of your coins, I doubt PVC was involved - just whatever happened to be in suspension in the soil.

Let's await some members who are more experienced with this type of corrosion. It's the 4th of July weekend; I doubt we'll see many regulars before Monday.

The PVC in album pages are interesting stuff.
I have seen red Unc. bronze coins survive for 20 years or more in this material.
I have also seen red Unc bronze coins turn black under the same conditions.

PVC album pages are made of soft PVC; that is, they have and oily plasticiser in the plastic to make them flexible.
It is this oily substance that slowly gasses out over a period of years and that is what, in most cases, affects the coins.
That being the case, the problems caused by the gassing out of the plasticiser can be, in most cases, alleviated by a good acetone bath.

However, the blackened coins are usually beyond the redemptive qualities of acetone, and will remain black.
In this case, there has been an inorganic toning caused by the presence of a chlorine or oxygen based chemistry that surrounds the coin.
A bath in organic acetone will not affect this sort of toning.

The best approach is to use non PVC album pages for your collection in the first place.
These pages will last much longer, and so will the coins.

If a coin has been buried or has been in a salt water environment, damage is usually result, and other cleaning methods have to be found to improve the presentation of the coin. There are many methods employed to improve the appearance of ancient coins, but in alomost all cases, the best ones are cleaned by professionals before they appear on the market.