New information on the source of milk spots and hazing

Discussion in 'Silver Coins' started by SpacePete, Sep 11, 2015.

  1. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    Fairly recent article posted by Texas Precious Metals:

    Would this be applicable to Perth Mint coins? I have a kilo kook with what looks like a liquid lubricant pattern around the rim.
     
  2. Silverpv

    Silverpv New Member

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    fricking lubricants... no wonder there are milkspots.... too much lube! :p

    Is the answer really, less lube? or cleaning up the lube after striking? lol...
     
  3. C.H.

    C.H. Member Silver Stacker

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    I believe it's true and easily explains the problem:

    They (Mints) know about it, but if they remove the lube their speed and subsequently volumes would suffer.
    I think they will try to wash the planchets/coins better, but this also slows down the process resulting in lower volumes or is impossible to do entirely.
    That's why older tech coins were/is fine, but all the new tech coins from PM are suffering from the same RCM plague.
    US Mint probably still uses the old tech.

    And I heard: "There is no such thing as too much lube" when dealing with women. :) Apparently not the case with coins. :(
     
  4. mmissinglink

    mmissinglink Active Member

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    Hello Bron, what say you?



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  5. dccpa

    dccpa Active Member

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    I knew it had to be a simple problem to fix. The mints that don't fix this problem don't care about their customers.
     
  6. barsenault

    barsenault Well-Known Member

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    Yeah Bron and Perth Mint team, don't go silent on us? Do you or do you not give a rats arse about your customers?
     
  7. mmissinglink

    mmissinglink Active Member

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    The equally or more important question though is:

    Can a technology be devised over the next few years in which milk spots, due to this alleged lubricant contamination, are able to be removed permanently from mirror proof coins in a way that no visible marks are left? If milk spots can be removed from mirror proof coin surfaces without leaving marks then I think it goes without say that it would be easier to remove milk spots from BU coin surfaces without leaving marks.

    If such a technology would be devised, it would be worth a fortune as there are many collectors who own many cherished coins (both raw and slabbed) that have milk spotted and I'm sure many of these collectors would pay to have some of their cherished coins restored to their pristine (pre-milk spotted) condition.



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  8. barsenault

    barsenault Well-Known Member

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    Hey missing, I've read that the milk spot is like an adhesive, where it is baked into the metal. If that could be removed without damaging the coin or medal, that would be amazing! Yes and the inventor would be sailing the deep blue seas on a yacht. :))
     
  9. bron suchecki

    bron suchecki Active Member Silver Stacker

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    A bit harsh, this was posted on a Saturday. I have forwarded it to our factory manager for comment. I would be surprised if something so obvious was not on the list of probably causes by our guys.
     
  10. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    Some more on this particular theory:

     
  11. hiho

    hiho Active Member Silver Stacker

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    I still think it's a dissimilar metal issue
     
  12. bron suchecki

    bron suchecki Active Member Silver Stacker

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    Our operations manager said it is a possible answer for haze/cloudy surface in that the washing solutions have not been rinsed off properly. He does not believe this an issue for us.

    The causes we are focusing on are housekeeping ie debris landing on the surface, and inclusions in the blank, which we are obviously trying to minimize. He says inclusions can trap small quantities of cleaning solutions, which could result in white spots, and also sometimes the inclusions contain crucible materials (from the melting of the silver), which could cause white spots as well as damage the coining die.
     
  13. barsenault

    barsenault Well-Known Member

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    ^^ Thanks for listening to your customers. Thanks for valuing our feedback. It really is key to the long-term success of folks like me and many others making investments into your products. Thanks again.
     
  14. mmissinglink

    mmissinglink Active Member

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    Hi Bron,

    I echo the appreciation others have made of you to vigilantly keep on top of this very serious problem of milk spotting.

    What collectors like me want is:

    1) The definitive reason as to why these milk spots are developing (and I understand the folks at the mint are currently working on trying to get to knowing this answer)

    2) Whether it's possible that a method can be devised in which the milk spots can be removed from proof coins that are already in the hands of collectors in a way that no visible damage is caused to the coin by the removal of the milk spots

    3) What specific steps the Perth Mint will take (once the definitive reason for milk spotting is understood) to ensure that the collector coins they produce will have no (or infinitesimally small) likelihood of developing milk spots due to the Perth Mint production process.

    Thank you.




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  15. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    I wonder if a single cause can be identified, or if it is multiple things?


    From the Chinese mint investigation:

     
  16. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    There's some interesting comments and speculation in the thread I linked to above.

    On removal of spots:
     
  17. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    The Perth Mint electron microscope images in an earlier thread would indicate the spots can't be removed without leaving indentations on the the surface of the coin where the silver has been consumed.

    That is echoed in this comment:
     
  18. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    For causes, note one of the points from the poster on the other forum:

    So maybe the problem with pollutants has always been there, but the change in the minting process makes spotting more likely to occur now.

    Mechanical polish vs. chemical treatment.
     
  19. Miloman

    Miloman Active Member Silver Stacker

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    Looked at the evidence. I'd say it is definately the "wash" solution. I'd put money on it!
     
  20. mmissinglink

    mmissinglink Active Member

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    Great data collecting SilverPete! You've earned your star for the month!



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