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I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
While this method should work on any penny, it's safe on the more recent ones, while the previous methods are not. The acidity of methods 1-4 will turn your zinc pennies black. After 1982, copper became too expensive to justify using on a coin just not worth anything. Therefore, zinc (a much cheaper metal) started being used.