Loading ...
Sorry, an error occurred while loading the content.
 

Re: Pre or post mint?

Expand Messages
  • dermestid
    A few more points. Examination of a coin under a microscope is sometimes helpful in detecting plating jobs. Microscopic gaps sometimes can be seen and these
    Message 1 of 6 , May 8, 2002
      A few more points.

      Examination of a coin under a microscope is sometimes helpful in
      detecting plating jobs. Microscopic gaps sometimes can be seen and
      these reveal the underlying metal.

      Some people claim to be able to detect a plated coin by sight alone.
      Heavy electroplating is readily detected by virtue of the mushy-
      looking design elements. However, thin deposits might not be so
      easily detected. There are other ways to plate coins as well. "Wash
      plating" is hard to detect. Here coins are immersed in a solution
      saturated with metal ions itching to attach themselves to the nearest
      compatible surface.

      I have seen numerous plating jobs that are so convincing that I have
      been unable to distinguish them from the real thing.

      Apart from the "scratch test" applied to the edge of a coin, one can
      sometimes also use a specific gravity test or a test of electrical
      conductivity to distinguish real from bogus coins.

      As I mentioned before, weight is an unreliable indicator. I have a
      1965 Columbia 2 centavos with two layers of plating -- nickel and
      over that, brass (I think). Yet, the coin weighs LESS than all the
      normal coins I used for comparison. The coin managed to perplex
      several well-known collectors. I resolved the problem with
      the "scratch test".
    • jscraton
      ... the ... able ... Well, I got permission from the owner to test the rim of the coin. He said go for it . Here are the results:
      Message 2 of 6 , May 10, 2002
        > Shallow scratches sometimes don't penetrate thick plating. Since
        the
        > coin is already worn and scratched, I would scrape the edge of the
        > coin against a very fine-grained sharpening stone. Give it a good
        > hard scrape. Then examine the edge under a 10X lens. You'll be
        able
        > to tell if there's copper under the silver-colored surface.
        > Natrually, I would not recommend this procedure for an uncirculated
        > coin.


        Well, I got permission from the owner to test the rim of the coin. He
        said "go for it". Here are the results:
        http://home.pacifier.com/~craton/plated.JPG
        Jason
      • dermestid
        That s certainly definitive. You went through the zinc plating that was applied outside the mint, then through the copper plating, and down to the zinc core.
        Message 3 of 6 , May 10, 2002
          That's certainly definitive. You went through the zinc plating that
          was applied outside the mint, then through the copper plating, and
          down to the zinc core.

          Sometimes invasive methods are the simplest and most direct way to
          solve a mystery. You have proven my point that plated coins are not
          necessarily heavier than a normal coin.

          >
          > Well, I got permission from the owner to test the rim of the coin.
          He
          > said "go for it". Here are the results:
          > http://home.pacifier.com/~craton/plated.JPG
          > Jason
        • dermestid
          Jason s case of a zinc-plated cent reminds me of another coin in my collection. I bought a beautifully struck, uncirculated, apparently unplated zinc cent with
          Message 4 of 6 , May 20, 2002
            Jason's case of a zinc-plated cent reminds me of
            another coin in my collection. I bought a beautifully struck,
            uncirculated, apparently unplated zinc cent with a dark gray
            coloration. At first I thought it was a normal cent that was zinc
            plated outside the mint because it was slightly overweight (2.52
            grams) and the surface was marked with a few microscopic bubbles
            or "blebs".

            I didn't pay much for the coin, so I scraped the edge against a fine-
            grained sharpening stone. Believe me, I gave it a good, hard
            scrape. Lo and behold, no copper lay beneath the surface. It turned
            out to be legit. I can only assume that the planchet itself was
            slightly overweight, and the scattered bubbles were created by some
            step in processing. The copper plating could not have been
            chemically stripped off outside the mint. If this had been the case,
            the surface would show some roughness and the design features would
            be a little mushy.

            It just goes to show you how tricky some of these errors can be.




            --- In errorcoininformationexchange@y..., "dermestid" <mdia1@a...>
            wrote:
            > That's certainly definitive. You went through the zinc plating
            that
            > was applied outside the mint, then through the copper plating, and
            > down to the zinc core.
            >
            > Sometimes invasive methods are the simplest and most direct way to
            > solve a mystery. You have proven my point that plated coins are
            not
            > necessarily heavier than a normal coin.
            >
            > >
            > > Well, I got permission from the owner to test the rim of the
            coin.
            > He
            > > said "go for it". Here are the results:
            > > http://home.pacifier.com/~craton/plated.JPG
            > > Jason
          Your message has been successfully submitted and would be delivered to recipients shortly.