Your copper cookware requires special care to continue to look its best.
After use, rinse copper cookware as soon as possible under warm, running water and use a mild soap such as dishwashing liquid to remove surface dirt.
Resist the urge to submerge: Less is more with this precious metal.
Wear gloves to protect the metal from fingerprints. Cotton is best, but rubber works as long as you wash a new pair first. (Any sulfur that remains on the gloves could cause it to tarnish.)
Always test a small area of your copper piece first to make sure the polishing compound is compatible with your piece before tackling the entirety.
Finally, dry copper cookware with a clean, lint-free rag such as an old T-shirt or well-worn towel.
Here's how to restore the lovely finish of your copper cookware once it's clean:
Moisten salt with vinegar or lemon juice to make a paste for a bright finish, or a paste or rotten-stone (decomposed limestone that is used in powder form as a polishing material) and olive oil for a dull finish. You can also simply sprinkle salt on the dull areas and then scrub with a vinegar-soaked rag.
The job is made even easier if you run hot water over the bottom of the copper pan first. The heat helps the salt and vinegar do their job.
One final tip: Don't use your copper utensils or pans with copper interiors to store acidic foods such as fruits, salad dressings, tomatoes, or anything containing vinegar. Toxic compounds can form if acidic food is cooked, stored, or served in copper pots or pans.