- File around the edge of a post-1982 penny until you see white zinc.
- Don protective gear, and drop the penny into a small bowl of undiluted hardware-store muriatic acid.
- Wait 15 to 60 minutes until the bubbles stop.
- With the faucet running, pour the acid into the sink through a strainer to catch the penny. (Never pour water into acid-it can boil instantly and splatter acid in your face. Always pour the acid into water.)
- Run water through the strainer for several minutes to rinse the penny half-shells and flush out the acid.