PVC damage on silver coins

Discussion in 'Ancient Coins' started by ambr0zie, Feb 28, 2021.

  1. ambr0zie

    ambr0zie Dacian Taraboste

    Hello ladies and gentlemen,
    I have 2 coins, from different auctions, but most likely from the same source (I have seen many coins with the same issue in the same auctions)
    upload_2021-3-1_0-44-27.png
    I got this coin because I liked the reverse, but as you can see, on the obverse the damage is quite extensive.
    The previous coin I got has the same problem (and also Julia Maesa, apparently she hates PVC). I soaked the old one in acetone - but not pure acetone as I don't have it, I need to buy some soon - but the effect was unnoticeable. I dipped it with a Q-tip and either I'm paranoid or some portions started to shine, unnaturally, so I just left it alone.

    Without the damage, this coin, and the other one, would have been quite attractive coins ...

    Do you think I should try something on this one or not? I am not bothered by the green spots and not very bothered about the damage itself, my only concern is if the coin will continue degrading.
     
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  3. robinjojo

    robinjojo Supporter! Supporter

    You should buy some pure acetone. The diluted acetone is not very effective, as you noted. The 100% acetone makes a world of difference.

    Now you mentioned that soaking the coin had no effect on the obverse. Judging from the photos the obverse might have deposits of oxides and not PVC deposits. Acetone has no effect on oxides.

    I just opened the image in Photoshop and enlarged it. It really does look like oxide buildup.

    So, I would suggest that you try soaking the coin in 100% acetone. The acetone will not affect the metal. If the deposit persists, try soaking the coin in distilled water for several hours or overnight, and see if any of the deposit can be dislodged with a toothpick.

    You might be able to remove some, but not all of the deposits. At this point I would leave the coin alone and let it tone. Once the bright areas start to darken naturally, over time, the coin will look better.

    The reason I suggest not to go further is that complete removal of the deposit might reveal a rough or corroded surface, or it might reveal a smooth surface - that's something of a gamble - you never know what lays beneath.
     
  4. ambr0zie

    ambr0zie Dacian Taraboste

    Thank you. I will buy some pure acetone as I know it doesn't affect coins.
    I am not sure if it's oxide - I soaked the previous coin, not this one (currently waiting for the coin in the thread to arrive)
    upload_2021-3-1_1-26-23.png
    They are very similar in condition (minimal circulation wear, but...) - I am 100% sure they belonged to the same person and I saw at lest 30 similarly damaged coins in 2 auctions.

    As you can see, in both examples, the damage affected the surface. Coin 1 obverse legend IVLIA MAESA A[vg] - VG gone.
    Coin 2 legend IVLIA MAES[A A]VG - AA gone.
    I checked the coin from this message, the letters are simplu "polished"
    I am not bothered too much - the problems reflected in the price, my only problem is making sure the damage doesn't evolve.
     
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  5. robinjojo

    robinjojo Supporter! Supporter

    My experience is that silver is much more stable than, say, bronze. Unless the silver has a high copper content, there shouldn't be any progressive corrosion, unlike bronze, where bronze disease can develop, especially in humid conditions over a period of exposure.

    The silver will darken over time, and that's a good thing, especially for an ancient coin.
     
  6. Only a Poor Old Man

    Only a Poor Old Man Well-Known Member

    Quick question regarding pvc damage. Does it only happen when coins are in direct contact with PVC material (in a pvc envelope) or does it also happen in the case where the coins are in archival safe envelopes, but happen to be stored inside a PVC box or case?
     
  7. Victor_Clark

    Victor_Clark standing on the shoulders of giants Dealer

    That doesn't look like PVC damage; which is why the acetone did not work. PVC residue on a coin feels a little greasy (which is why acetone removes it easily) and will also stain the flip. Below is a PVC flip with the insert showing stains.

    flip.JPG
     
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  8. hotwheelsearl

    hotwheelsearl Well-Known Member

    You can always try sodium hydroxide. It will remove the luster, but also remove any type of encrustations. Horn silver comes off with sodium thiosulfate.

    Use both at your own risk
     
  9. Marsyas Mike

    Marsyas Mike Well-Known Member

    Interesting problem - my PVC experience with silver is similar to the comment by @Victor_Clark - a greasy residue and green gunk on the flip. It comes off the coin with a thumb rub. I throw the flip away.

    I've had silver world crowns in PVC flips for 30 years or so and sometimes nothing happens at all, but occasionally, the green stuff appears. Mostly nothing happens, even after decades.

    It makes no sense to me - my coins are all stored in similar atmospheric conditions. I have never seen any actual surface damage happen to a silver coin as shown in the OP. That a collection has similar damage makes me wonder, though.
     
  10. ambr0zie

    ambr0zie Dacian Taraboste

    I have decided to leave the coins as they were. My experience with cleaning has been a disaster in general. I don't have the knowledge and the patience for a proper cleaning.
    And yes, there were 2 or 3 auctions (monthly) when about 20-30 coins with the same issues appeared and also similar condition, very nice details but parts with corrosion. All the coins where 3rd century denarii so I strongly suspect they were from the same collection.
     
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