Does anyone know how our canadian pennies fair in the pressed penny machines? I had read that if using american pennies that it was best to try to use pennies that were produced prior to 1981 as they contained copper (and not zinc), and hence seemed to come out looking better or clearer than the zinc ones. Does something similar hold true for our pennies? Any tips would be much appreciated as we have never done this and it looks like it could be something fun.