Viewing post #623337 by Horntoad

Xeramtheum said:This is an awesome idea but you want to use pennies made in 1981 and older. Those pennies are 95% copper. Pennies made after 1981 are only 2.5% copper and 95.5% zinc.

Even though they are only 2.5% copper, it is a pure copper plating around a zinc core. So any slug crawling across a modern penny is still coming in contact with pure copper and it will have the same affect as an older copper coin.