PVC residue on a NGC slabbed new style owl

Discussion in 'Ancient Coins' started by robinjojo, Jul 22, 2021.

  1. robinjojo

    robinjojo Well-Known Member

    I knew that there were some PVC residue deposits on the obverse of this coin when I bought it. The reverse was PVC deposit free.

    Athens New Style Owl, Detail NGC Slab, 124-3BC PVC Residue 7-20-21.jpg

    I was somewhat surprised that such obvious deposits got by NGC. So, I cracked open the slab and gave the coin an acetone bath (100% concentration).

    Now, the deposits appear to be gone. The bath was about 10 minutes long, followed by a rinse with distilled water.

    ATTICA, Athens, Circa 124/3 BC AR tetradrachm
    (28mm, 16.85 gm)
    New style coinage
    MIKIΩN, EYPYKΛEI and ΣΩKPATHΣ, magistrates.
    Helmeted head of Athena right / owl standing right on overturned amphora, head facing; To right, the Dioscuri standing slightly left; Letter E on amphora, ME below; All within a wreath.

    Thompson 483
    Good VF with a generally well centered strike.

    D-Camera Athens AR tetradrachm Circa 124-3 BC Thompson 483 16.85g exNGC 7-22-21.jpg

    I think this coin would not have been slabbed by NGC, had they known about the PVC deposits.

    Has anyone had similar experiences?
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  3. Insider

    Insider Talent on loan from...

    robinjojo, posted: "I knew that there were some PVC residue deposits on the obverse of this coin when I bought it. The reverse was PVC deposit free.

    I think this coin would not have been slabbed by NGC, had they known about the PVC deposits."


    :yawn: If you think NGC graders did not see the green deposits on your coin...:hilarious::hilarious::hilarious::hilarious:.

    TPGS slab coins with green PVC on them all the time!!!! Thankfully, you did what's best for your coin.

    I would have called you and asked permission to remove the PVC at no cost before grading. As I understand it, NGC often sends a form recommending conservation when the coin is returned.
    robinjojo likes this.
  4. robinjojo

    robinjojo Well-Known Member

    Actually, the coin came to me in this condition, and already slabbed.

    I think the acetone bath was effective. The deposits were not major in nature (I've seen much worse), and the surface seems not to have been damaged, fortunately.
    red_spork likes this.
  5. dltsrq

    dltsrq Grumpy Old Man

    I don't think the PVC deposits "got by" NGC. Rather, they would likely have contributed to the "surfaces" rating or if the coin came from a bulk submission, considered as part of the "net grade". NGC Ancients: Grading
    ominus1, Ryro and Insider like this.
  6. Insider

    Insider Talent on loan from...

    Thanks for the link. IMO, every coin collector should read it. However, I didn't read anything in the link about a soft green residue that is removed quickly by common chemicals contributing to a net grade.
  7. robinjojo

    robinjojo Well-Known Member

    The label that came in the slab gives it a 5 for strike and a 3 for surfaces, with the notation "scratches". There are some extremely small scratches on the owl's breast, along with some circulation marks, but nothing major at all. The reverse is oxidized somewhat, so perhaps that contributed to the surface condition number. I don't think the PVC deposits were taken into account.
    Insider likes this.
  8. Insider

    Insider Talent on loan from...

    Color me anal butt I still wish they would have removed the green for the submitter.

    I do it all the time when it is fast & easy but I'm not as busy as those guys. I've only gotten in trouble conserving a coin once. In the 1970's a collector sent in a red Proof 1936 cent he bought at auction described as having "beautiful sea-blue-green toning." It sure was - dripping with LIQUID PVC :facepalm: in the wet plastic flip. I removed the liquid. When he got the coin back he had a fit! :rage: and accusing us of switching his coin! We bought it back from the confused :bucktooth: collector to settle the matter and then we sold it to a dealer for a profit.
    robinjojo likes this.
  9. dltsrq

    dltsrq Grumpy Old Man

    I don't believe NGC Ancients offers conservation. NGC has a separate division for that, with additional fees of course. Numismatic Conservation Services (NCS)
    robinjojo likes this.
  10. robinjojo

    robinjojo Well-Known Member

    Sounds like a job for Lloyd Bridges!

  11. Insider

    Insider Talent on loan from...

    Interesting. I guess a submission form from the ancient division would answer that.
    Anyway, there is conservation and CONSERVATION. The OP did a beautiful job of conservation. I believe many of us could do the same thing in much less time. This type of conservation took me less than a minute using a microscope so as not to damage the coin.



    No comments about the colors or white balance please. :yawn:

    "CONSERVATION" is entirely different. ;)

    Attached Files:

    robinjojo likes this.
  12. robinjojo

    robinjojo Well-Known Member

    Nice job!

    I kept my coin in the acetone bath probably longer than necessary, but since the acetone is benign as far as silver is concerned, I just kept the owl in the bath longer, to be on the safe side. A thorough rise with distilled water finished the process.
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