PVC and/or Vertigris How do I proceed?

I removed the coin from the acetone and scanned it. The results aren't as dramatic as the first bath it took. Still, I'm going to replace it in fresh acetone and give it more time.

The green film on the reverse seems to be getting thinner, except between the top of the left wreath and the shield. That is pretty much filled in. It is very tempting to pick it out with a rose thorn but I shall resist.

Running diagonally from 11 o'clock to 5, there are 7 spots on the obverse that look like they are more than a film. I'm hoping these will dissipate with more soaking in acetone.

Bruce

 

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That verdigris is not going anywhere with acetone (or any other organic solvent).

Soak the coin in distilled water to solubilize the verdigris acids. If you want to continue down the safe conservation path, you should move to xylene next. Acetone has done all it can at this point IMO. Xylene will not remove the verdigris either, but if there's any acetone insoluble organics left on the surface, it will remove those.

 

If you don't mind paying the money I would guess NCS will easily remove that, but otherwise I am sure Thad's advice is sound (those chemist people might know a few things).

 

I'll wager that coin ain't going to get better unless you completely strip it and recolor it. Even then, the spots have likely already affected the surface and they will likely be visible even after the stripping/recoloring. If I were the OP I would simply sell the coin and find one that doesn't have these problems. It's not like a circulated 1869 is a rare coin.

 

p.s. threads like this are precisely why (cough, some, cough) people need to be careful condoning improving copper when the vast majority of situations it is not warranted or beneficial in the long run. I wonder if the OP would have even purchased the coin had he not been led to believe improvement is possible by what he read here.

 

PVC residue is actually the plasticizer used in the PVC to give it flexibility. As the PVC degrades the plasticizer is released along with hydrochloric acid. The plasticizer is soluble in organic solvents which is why acetone does a good job dissolving it. However, the hydrochloric acid not only eats into the coin surface, it has the potential to form verdigris, i.e. cupric chloride in this case.

This is beside the point, I can tell from the pictures that garden variety verdigris is present. This coin has been exposed to moisture and air for an extended period and what we're seeing at minimum is copper chloride, copper carbonate and copper hydroxide.

 

So you " know you can remove the contaminants safely" ? As in vertigris or pvc? Or you want to turn the coin into the beauty within?

 

It seems that the acetone step would remove pvc if thats what it is and the case settled there right? Vertigris wont come off with acetone. Yet what if you actually damage the coin? By removing vertigris if its that and exposing pits or lifting out detail in patina? Patina as in the brown surface layer isnt a bad thing right? No red gems are even listed in pcgs pop. For '69s so why not settle for a 45+ grade brown and avoid getting a details/cleaned grade and drop its value lesser than where its at now?