What happens when you store vinegar in copper?

The hidden chemistry of copper and acid

Copper cookware has a timeless aesthetic and exceptional thermal conductivity, but it requires careful handling. When acidic foods or residues—such as vinegar, lemon juice, ketchup, or even baking soda—come into direct contact with copper surfaces, a chemical reaction occurs.

This interaction strips away the metal's natural tarnish, leaving behind bright, shiny spots where the acid has effectively cleaned the metal down to its bare composition. While these bright patches might look harmless, leaving acidic substances sitting in copper pots can cause the metal to leach into your food.

Key takeaway: Always wash and dry copper items promptly after use, and never use them for storing acidic ingredients or leftovers.