What caused this colorful rainbow?

Discussion in 'US Coins Forum' started by Insider, Dec 8, 2021.

?

What caused this characteristic?

Poll closed Dec 9, 2021.

  1. Chemical Cleaning

    9 vote(s)
    42.9%

  2. Ink

    0 vote(s)
    0.0%

  3. Album Toning

    2 vote(s)
    9.5%

  4. Lacquer

    8 vote(s)
    38.1%

  5. Photographic artifact

    2 vote(s)
    9.5%
Page 2 of 2
  1. ddddd

    ddddd Member

    That was my thought too. Reading the other replies I’m convinced by the lacquer group.
     
    ddddd, Dec 9, 2021
    #21 + Quote Reply
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  3. -jeffB

    -jeffB Greshams LEO Supporter

    As I understand it, you get interference patterns from a transparent layer because of reflected light from the deeper surface interfering with reflected light from the nearer surface. You can see this even in layers of macroscopic thickness, if they're flat enough (relative to each other).
     
    -jeffB, Dec 9, 2021
    #22 + Quote Reply
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  4. Pickin and Grinin

    Pickin and Grinin Well-Known Member

    This Australian Half Penny has the same tones, I can gaurantee that is doesn't have any oil, or lacquer added to the coin. It is from a seller that is known for cooking his coins.
    upload_2021-12-9_17-49-43.jpeg
    upload_2021-12-9_17-53-5.jpeg
     
    Pickin and Grinin, Dec 9, 2021
    #23 + Quote Reply
  5. -jeffB

    -jeffB Greshams LEO Supporter

    That's a very different look, though, even if it includes the same colors. Interference fringes from a thin clear coat tend to have those fingerprint-like contours showing in the OP's photos.
     
    -jeffB, Dec 9, 2021
    #24 + Quote Reply
  6. Pickin and Grinin

    Pickin and Grinin Well-Known Member

    I hear ya.
    It's not always just a coating on the coin, I don't buy from photos. So I defer, just throwing out some of the same tone evidence, heck this one could have been coated in MS70? In hand the coin doesn't look oily, It looks like many other Half Penny's that I have seen.
     
    Pickin and Grinin, Dec 9, 2021
    #25 + Quote Reply
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  7. Marshall

    Marshall Junior Member

    Just a thought. Sometimes, you find fingerprints on very old coins and natural toning around a fingerprint might cause this effect.
     
    Marshall, Dec 10, 2021
    #26 + Quote Reply
  8. Marshall

    Marshall Junior Member

    I sometimes wonder what the oldest known fingerprint is on. I would not be surprised if it were an ancient coin. I'm pretty sure I've seen them on Old Hibernia or Conder Tokens in relatively good states of preservation. I see no reason older coins would not exhibit similar characteristics.
     
    Marshall, Dec 10, 2021
    #27 + Quote Reply
  9. GDJMSP

    GDJMSP Numismatist Moderator

    If I'm understanding your comment correctly Jeff this is what you're talking about - yes ?

    upload_2021-12-10_9-12-34.png


    Those lines, around the E above and above the letters below, that are close together like contour lines on a topo map. And if you look at at just the E you can see they completely surround the E. You won't ever see lines like that are caused by toning.


    upload_2021-12-10_9-16-52.png


    I like the way you said it, phrased it, it's simple, clear, and easily understood by all I believe.

    But we need to remember that that's not the only identifying characteristic of a coin with lacquer on it, there are others as well. And they don't always cause that colorful look seen on this coin.

    You see several other examples of lacquer on a coin, and what it can also look like at times, here -

    https://www.ngccoin.com/news/article/5789/NCS-coin-conservation-lacquer/

    In the article they talk about the doubling effect that can sometimes be seen around the legends, and that's most easily seen in the before and after pics of the Mercury dime. The other pics show you different looks it can have.

    edit - I would add that what John, messydesk, said is accurate as well when it comes to answering the question I asked - just a different way of saying it.
     
    GDJMSP, Dec 10, 2021
    #28 + Quote Reply
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  10. GDJMSP

    GDJMSP Numismatist Moderator

    And Mike, hope you're not too busy at that show so you can stop in and comment.
     
    GDJMSP, Dec 10, 2021
    #29 + Quote Reply
  11. messydesk

    messydesk Well-Known Member

    Hard to say if the fingerprint on a coin is as old as the coin in most cases. I have seen fingerprints on GSA CC Morgans, though. These were supposedly only handled with gloved hands when they were packaged, so those fingerprints would have dated to when the coins were bagged.

    I imagine that the oldest known fingerprints are on pottery.
     
    messydesk, Dec 10, 2021
    #30 + Quote Reply
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  12. Marshall

    Marshall Junior Member

    https://www.neilbockoven.com/2019/05/06/the-oldest-fingerprint-from-an-early-modern-human/

    Interesting article about oldest fingerprints.
     
    Marshall, Dec 10, 2021
    #31 + Quote Reply
  13. -jeffB

    -jeffB Greshams LEO Supporter

    Exactly. The interference fringes I've seen do exactly that around features that poke into the layer.
    I'll just be over here having a moment...
    [​IMG]
     
    -jeffB, Dec 10, 2021
    #32 + Quote Reply
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