Sterling silver can be cleaned in a number of ways. The oxidation that coats the outside of sterling silver is called a patina. It can be removed using borax, aluminum foil and water. The water should be very warm or boiling. Boil the water before pouring it on the aluminum foil if the silver's surface has a heavy patina.
Toxicity
It is important to wear rubber gloves when working with borax. It is a toxic chemical that should not be ingested. The toxicity level is low, but precautions should be taken to avoid exposure. Keep borax away from children and pets.
Placement
Line a glass container that is larger than the sterling silver items to be cleaned with aluminum foil. Plastic and metal containers do not provide the best chemical reaction, but they will still work. The sterling silver is placed so each item has one surface directly on the aluminum foil. This is necessary so the chemical reaction between the aluminum foil and the sterling silver will occur.
Process
Line a glass container with aluminum foil and place the sterling silver in one layer with no pieces touching. Combine 1 teaspoon to 1/4 cup of borax into enough boiling water to cover the sterling silver item or items. Let the water cool, then pour into the sink. Wipe the sterling silver off with a clean, soft cotton cloth.