Clean copper with salt, white vinegar, water and dishwashing liquid in a pot large enough to hold the item. Polish copper with another mild acid, salt, flour paste or tomato paste.
To clean copper, fill a large pot with water and add a tablespoon of salt and a cup of vinegar. Add the copper item, bring the water to a boil and let the copper item boil for a few hours. Then, turn off the heat and allow the pot and its contents to cool. Wash the copper item with dishwashing detergent, rinse it ,and dry it with a soft, lint-free cloth. One caveat to this method is the pot the copper is boiled in should not contain zinc.
To polish copper, wash the piece with warm water and allow it to dry. Then, rub the cleaning solution into the places that are tarnished with a soft cloth. The cleaning solution can be vinegar, salt or flour paste if the tarnish is mild or one part lemon juice and one part salt if the tarnish is severe. Tomato paste is also a good cleaner. Work the solution into the tarnished area, and then rinse with clear water. Dry with another cloth, and then buff until the copper shines. The application of beeswax gives an lasting luster to copper.