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Rough Life of a Coin - Part two
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<p>[QUOTE="John Burgess, post: 6502852, member: 105098"]The edge suggest it was soaked in an acid strong enough to eat copper but too weak for the nickel. As far as all the cracking it's also post mint damage I'm sure, but I'm not sure of the cause.... I'm thinking an experiment with sulfur embrittlement.</p><p><br /></p><p>Combining the two observations, i'd have to guess a dip in sulfuric acid H2SO4 it would be a slow reaction but adding H2O2 hydrogen peroxide to it as an oxidizer would dissolve an entire nickel in about 30 seconds and generate a lot of heat in the process. A quarter is a copper core, the clad layers on each side are 75% copper 25% nickel.</p><p><br /></p><p>I'd think by soaking in the sulfuric acid it would eat the copper faster than the nickel and the sulfur in the formula would cause brittleness to the nickel that's been weakened by the copper being extracted at the faster rate. IF they added the hydrogen peroxide to speed the process it would just be a quick dip and a high temp violent reaction which I think could cause splitting.</p><p><br /></p><p>I'm sure it's PMD. I THINK that's how it was done based on the pictures. I haven't seen something quite like this before, but I've seen the edge before and know it was an acid to do that. I've also seen sulfur embrittlement in nickel in the plating process when the nickel is contaminated. It just cracks and flakes off.[/QUOTE]</p><p><br /></p>
[QUOTE="John Burgess, post: 6502852, member: 105098"]The edge suggest it was soaked in an acid strong enough to eat copper but too weak for the nickel. As far as all the cracking it's also post mint damage I'm sure, but I'm not sure of the cause.... I'm thinking an experiment with sulfur embrittlement. Combining the two observations, i'd have to guess a dip in sulfuric acid H2SO4 it would be a slow reaction but adding H2O2 hydrogen peroxide to it as an oxidizer would dissolve an entire nickel in about 30 seconds and generate a lot of heat in the process. A quarter is a copper core, the clad layers on each side are 75% copper 25% nickel. I'd think by soaking in the sulfuric acid it would eat the copper faster than the nickel and the sulfur in the formula would cause brittleness to the nickel that's been weakened by the copper being extracted at the faster rate. IF they added the hydrogen peroxide to speed the process it would just be a quick dip and a high temp violent reaction which I think could cause splitting. I'm sure it's PMD. I THINK that's how it was done based on the pictures. I haven't seen something quite like this before, but I've seen the edge before and know it was an acid to do that. I've also seen sulfur embrittlement in nickel in the plating process when the nickel is contaminated. It just cracks and flakes off.[/QUOTE]
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Rough Life of a Coin - Part two
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