Water and Soap
Decorative copper pieces are often covered in a thin coat of lacquer, thus preventing them from oxidizing. These lacquered pieces can be cleaned by dusting or washing them in a bath of soapy, lukewarm water. These lacquered decorative pieces should never be polished. Some eating and cooking utensils are lacquered as well, but the lacquer needs to be removed from these items before using them. Boiling these utensils in a few gallons of water and washing soda can make it possible to simply peel the lacquer right off.
Salt, Vinegar and Flour
Copper items that are only slightly dirty or tarnished can be cleaned with a paste made with equal parts of salt, vinegar and flour. Mix up the paste in a bowl and then apply to a clean cloth. Coat the copper object in the paste, and then rinse and buff.
Extremely stubborn stains and buildup can be removed from copper by using lemon juice. The acidic nature of lemon juice makes it perfect for cleaning some types of metal, including copper. Again, use a clean cloth to apply the lemon juice to the surface of the copper object. Actual lemon halves dipped in salt can also be used to clean copper. Lemon oil can help keep indoor brass items bright as well.
Paste wax maintains a shine on outdoor copper items. Floor waxes and car waxes both work for this purpose. After thoroughly cleaning an outdoor copper item, cover it with a thin coat of paste wax. Beyond keeping the item bright, this also helps protect it from the elements.