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Well that's one way to get "cameo"

mt_mslamt_msla Posts: 815 ✭✭✭✭

Weird black toning on the Lincoln cent. All coins are still in the proof OGP.


Insert witicism here. [ xxx ]

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    rickoricko Posts: 98,724 ✭✭✭✭✭

    That is weird tarnish... did you say they are proofs?? Sure do not look like it.... well, could be just the picture angle etc.. Cheers, RickO

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    mt_mslamt_msla Posts: 815 ✭✭✭✭

    Insert witicism here. [ xxx ]

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    ModCrewmanModCrewman Posts: 4,027 ✭✭✭✭✭

    Not really very attractive IMHO; but that's not saying I wouldn't have bought it too just for the novelty of it.

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    JBKJBK Posts: 14,788 ✭✭✭✭✭
    edited November 3, 2017 9:59AM

    I am a little confused by the close-ups but the full shot shows that the cent is loose in the plastic and may have been resting against the dime (are there any tears to the outside air?).

    If the cent spent some years touching the dime then I wonder if that caused the excessive tarnish. There is some kind of chemical or electrolytic or metallurgical process whereby certain metals can be protected and others sacrificed by being in contact with each other. For example, I recall two silver bowls in the Titanic debris field and one was resting on the ocean floor and was as crusty as you might expect, but one was sitting on a piece of the steel hull and was as clean and shiny as the day it sank. It had something to do with the iron pulling away all the reactive processes from the silver. (Sort of like the idea behind Intercept Shield, but that is a chemical thing).

    It is all voodoo to me, but there might be a scientific explanation. (Or not).

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    PRECIOUSMENTALPRECIOUSMENTAL Posts: 961 ✭✭✭✭

    It does appear that the cellophane was compromised, you can see that in the pics.
    I have a bunch of 1964 proof sets, the only coins that toned were the nickels, sort of a purple-bluish hue.

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    JBKJBK Posts: 14,788 ✭✭✭✭✭

    @PRECIOUSMENTAL said:

    I have a bunch of 1964 proof sets, the only coins that toned were the nickels, sort of a purple-bluish hue.

    I have a 1961 proof set with a nickel like that. I love it. I haven't seen it in a while - I need to check it out.

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    jmlanzafjmlanzaf Posts: 32,003 ✭✭✭✭✭

    @JBK said:
    I am a little confused by the close-ups but the full shot shows that the cent is loose in the plastic and may have been resting against the dime (are there any tears to the outside air?).

    If the cent spent some years touching the dime then I wonder if that caused the excessive tarnish. There is some kind of chemical or electrolytic or metallurgical process whereby certain metals can be protected and others sacrificed by being in contact with each other. For example, I recall two silver bowls in the Titanic debris field and one was resting on the ocean floor and was as crusty as you might expect, but one was sitting on a piece of the steel hull and was as clean and shiny as the day it sank. It had something to do with the iron pulling away all the reactive processes from the silver. (Sort of like the idea behind Intercept Shield, but that is a chemical thing).

    It is all voodoo to me, but there might be a scientific explanation. (Or not).

    "Sacrificial anode". It's also the way they time the death of your hot water heater. There's a magnesium rod in there. The magnesium "rusts" (oxidizes) which prevents the iron from oxidizing UNTIL the magnesium is gone. If they put in a short rod, you have a 7 year heater, medium rod gets you a 10 year heater, longer rod gets you a 20 year heater.

    Silver is much harder to oxidize than copper. So, if you have silver in contact with copper, the copper would preferentially oxidize. However, the silver doesn't actually make the copper oxidize. There has to be an oxidant present.

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