Are these 'milk spots'?

Discussion in 'Coin Chat' started by Atarian, Oct 31, 2012.

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  1. Atarian

    Atarian Well-Known Member

    I gently rubbed one (on the devices) with a Q-tip and it had no effect. I then chickened out and left the coin alone.

    Are these 'milk spots'?

    Thanks.

    IMG_3236.jpg
     
    Atarian, Oct 31, 2012
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  3. Detecto92

    Detecto92 Well-Known Member

    Yup.
     
    Detecto92, Oct 31, 2012
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  4. green18

    green18 Unknown member Sweet on Commemorative Coins Supporter

    Jonah and the whale?
     
    green18, Oct 31, 2012
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  5. Atarian

    Atarian Well-Known Member

    That's the one! I was a bit disappointed when it arrived in this condition...
     
    Atarian, Oct 31, 2012
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  6. Detecto92

    Detecto92 Well-Known Member

    I see milk spots on a lot of new coins, do mint workers have a bad case of the sniffles? Sneezing all over coins.
     
    Detecto92, Oct 31, 2012
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  7. green18

    green18 Unknown member Sweet on Commemorative Coins Supporter

    From whence came it (country)?
     
    green18, Oct 31, 2012
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  8. Atarian

    Atarian Well-Known Member

    Israel.
     
    Atarian, Oct 31, 2012
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  9. green18

    green18 Unknown member Sweet on Commemorative Coins Supporter

    Beautiful piece......
     
    green18, Oct 31, 2012
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  10. lonegunlawyer

    lonegunlawyer Numismatist Esq.

    Yes, beautiful.
     
    lonegunlawyer, Oct 31, 2012
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  11. desertgem

    desertgem Senior Errer Collecktor

    I wonder if milk spots are associated with the "frosting of the dies" techniques that the mint uses to try and give every one frost cameos? Maybe from die contamination? Posing it as a question as I have no info on the chemicals used.
     
    desertgem, Nov 1, 2012
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  12. lonegunlawyer

    lonegunlawyer Numismatist Esq.

    I thought it had to do when they washed the planchets.
     
    lonegunlawyer, Nov 1, 2012
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  13. desertgem

    desertgem Senior Errer Collecktor

    I've heard that also, but most of the "milk spots" are relatively small, and I am wondering if this was the case, how the "wash" stayed on the planchet during the high pressure strike. Oh well,
     
    desertgem, Nov 1, 2012
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  14. easj3699

    easj3699 Well-Known Member

    i rarely ever see a newer philharmonic without with milk spots
     
    easj3699, Nov 1, 2012
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  15. GDJMSP

    GDJMSP Numismatist Moderator

    No one has as of yet discovered what causes milk spots, but there are theories. From what I have read, the mint has no idea what causes them either. And to date, none of their experiments or testing has been able to prevent them.

    Nor has any way ever been discovered to remove them. PCGS once offered a $25,000 reward to the first person that could figure out a way to remove them without harming the coin. To my knowledge that reward offer still stands.

    There are many peculiarities about milk spots. They do not always appear on the coin right away. Sometimes months or even a year after the coin was minted and then even slabbed, the spots mysteriously appear. And they can grow worse with time, or not. They cannot be dipped off and they cannot be rinsed off.

    And many people mistakenly misdiagnose other kinds of spots as being milk spots when they are not milk spots at all.
     
    GDJMSP, Nov 1, 2012
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  16. kydedhed

    kydedhed Member

    kydedhed, Nov 1, 2012
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  17. Derick

    Derick Well-Known Member

    I have been working in metallurgy technology development for the last 12 years and I think there is a possibility that these "milk spots" could be silver chloride occuring as a "white" toning or tarnish if you may on the metallic silver surface. This could be due to exposure, do not know exactly how, to hypersaline high or salt environments. Silver chloride has a very low solubility in water at ambient conditions, but solubility does occur to minor extent above 50 oC. It might be worth putting a coin with milk spots in distilled water above 50 oC and note if the spots dissolve.
     
    Derick, Nov 1, 2012
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  18. BadThad

    BadThad Calibrated for Lincolns

    I don't own any coins with milk spots or I'd put one on our SEM-EDXRF to determine what the composition is. It's been on my coin chemistry "wish list of things to do" for years now.
     
    BadThad, Nov 1, 2012
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  19. Detecto92

    Detecto92 Well-Known Member

    That's a good theory but I've seen them on copper cents too.
     
    Detecto92, Nov 1, 2012
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  20. Derick

    Derick Well-Known Member

    Copper I chloride is also white (CuCl not CuCl2). Can also turn slightly green over time. Very low solubility in water at ambient as well.
     
    Derick, Nov 1, 2012
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  21. Derick

    Derick Well-Known Member

    For 25 000 US you might consider moving it up a notch on that list
     
    Derick, Nov 1, 2012
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