Copper Patina Guide
Copper Patina Guide | CopperSmith
Show less Cleaning copper can be done in a number of ways, mostly using what you have at home already. Here are some of the most preferred methods. Believe it or not, ketchup is excellent for removing oxidation from copper. This method is probably better for small areas due to the mess. If you have a copper item that you need to clean, cut a lemon in half and squeeze out all of the juice. Mix salt into the juice a little at a time until it forms a paste.
Copper Reactivity: Patination
Exposure to air can cause your copper to oxidize and tarnish with a blue-green patina. Many common cleaners leave this patina untouched. Prep to remove oxidation by verifying the metal item is really copper and checking for the presence of lacquer. Remove oxidation from copper with a paste made of white vinegar, salt, and flour. Prevent oxidation with a thin coat of virgin olive oil or lacquer.
Metals can be listed according to their reactivity. Some, like sodium, are so reactive that they explode on contact with water. Some, like gold, are so unreactive that they appear to be unchanged after being buried for thousands of years.