It is a constant struggle to convince new collectors that zinc pennies are not as durable as copper. They think “shiny” means good.
Here’s vivid proof of the problem with zinc pennies. Zinc pennies (in the U.S., they were produced from 1982 to date) are zinc with a thin coating of copper. That thin coating can flake off and often has the appearance of waves. It is unstable and unsightly.
The pennies below were pressed on “shiny new pennies.” You can see that a longer roll stretches that thin copper coating beyond its capacity.