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Posted 04/16/2008 8:26 pm
First, hi Rick, have not seen you recently and good to hear from you.
Now, out of curiousity, I took a 1909 (worn to almost smooth) a bad 1947, 1963 and 1981, plus a 1989 to represent the modern zinc filled coin and ran a test. I took a fine metal file and took each coin on edge and applied them with a fair amount of pressure and drew them slowly across the file. The file bit into the pre-1982 coins and with enough pressure almost want to dig in and stop. On the 1989, the copper layer was remove immediately and as soon as the file hit the zinc it wanted to skate. I would compare it to the difference in pulling file across wood vs glass. I understand your hardness research, but the file test makes the zinc seem harder. Any thoughts anyone?
Jim
Now, out of curiousity, I took a 1909 (worn to almost smooth) a bad 1947, 1963 and 1981, plus a 1989 to represent the modern zinc filled coin and ran a test. I took a fine metal file and took each coin on edge and applied them with a fair amount of pressure and drew them slowly across the file. The file bit into the pre-1982 coins and with enough pressure almost want to dig in and stop. On the 1989, the copper layer was remove immediately and as soon as the file hit the zinc it wanted to skate. I would compare it to the difference in pulling file across wood vs glass. I understand your hardness research, but the file test makes the zinc seem harder. Any thoughts anyone?
Jim
