Because silver is a soft, expensive metal, silver jewelry is forged from an alloy containing silver and copper or silver, copper and zinc. The one drawback to the inclusion of copper is its reddish hue. To correct this problem, silver jewelry is plated with a thin layer of pure silver. Normal wear and polishing will gradually rub the silver layer away, revealing the reddish color of the copper alloy. If you have a silver ring that is turning copper, you can restore its silver appearance using a simple chemical solution.
Don safety equipment. At a minimum, you should be wearing rubber gloves and safety goggles.
Prepare a sodium hydroxide solution by combining 24 grams of sodium hydroxide with 100 milliiters water in the beaker. Stir carefully using the glass stirring rod. The solution will become warm.
Bring the solution to a boil using the hot plate. Turn the hot plate off.
Add 5 grams of zinc power to the warm sodium hydroxide solution. The zinc will generate foam as it dissolves into the solution.
Clean your silver ring with steel wool. The ring should be free of dirt and moisture.
Carefully place the ring into the warm solution. Use the glass stirring rod to push the ring around the bottom of the beaker until it is covered in the zinc powder.
Wait three minutes and remove the ring from the beaker using the glass stirring rod. The ring will appear shiny silver in appearance.
After restoring the ring, rinse the ring in a sink under cold water to remove any remaining trace of zinc or sodium hydroxide. Always work in a well-ventilated area.
Zinc powder is highly flammable. Avoid using an open flame, like a stove top or a Bunsen burner. Sodium hydroxide solution is highly corrosive. Always use care when handling.
- Robert Krebs; "The History and Use of Our Earth's Chemical Elements: A Reference Guide"; 2006.
- Practical Chemistry; Turning Copper Coins Into 'Silver' and 'Gold'