[HELP] What causes these tiny black nodules in a pit in a handpour?

Discussion in 'Silver' started by SpacePete, Aug 1, 2015.

  1. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    Anyone know what these little black nodules are, and what causes them? They are really tiny and hard to photograph since I don't have a macro lense. They are in a tiny pit on the surface of the silver bar.

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    SpacePete, Aug 1, 2015
    #1
  2. Antalon

    Antalon Active Member Silver Stacker

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    looks like shards of graphite from a el cheapo mold?
     
    Antalon, Aug 1, 2015
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  3. Silver Soul

    Silver Soul Well-Known Member Silver Stacker

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    It looks like unburnt flux.
     
    Silver Soul, Aug 1, 2015
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  4. -j-p-shmorgan

    -j-p-shmorgan New Member

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    Most likely slag from casting. It looks to be glassy (like melted borax that one would use to lubricate a crucible).
    You can always hit the spot with H2SO4 and see what happens.
    It should dissolve the spot and leave the silver alone.
     
    -j-p-shmorgan, Aug 1, 2015
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  5. SpacePete

    SpacePete Well-Known Member Silver Stacker

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    Thanks everyone. It makes this old bar even more interesting. I'll have to try to some better pics.
     
    SpacePete, Aug 1, 2015
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