Our scientists celebrated Presidents’ Day by looking at pennies under a magnifying glass. Clearly, some of the pennies were shiny and some of them dull. Could they bring back the shine of the dull pennies?

The pennies were placed in three solutions — vinegar, detergent, and ketchup — to try to bring back the original shine of the copper. The acidity from the tomatoes and vinegar in the ketchup breaks down the copper oxidation that makes the pennies dull and dark. The ketchup brought back the shine!