Sterling, or 925 silver, is an alloy made up of 92.5 per cent silver and 7.5 per cent copper. Pure silver is an inert metal that cannot tarnish. However, pure silver is not suitable for jewellery or flatware manufacture because it is too soft in its pure state. The addition of copper makes the alloy stronger and more wear resistant. Alloying also makes the metal prone to oxidation or tarnishing. Oxidation occurs when copper/silver alloy is exposed to oxygen and certain chemicals and elements, such as sulphur and certain acids. Various methods of removing tarnish from sterling silver flatware and jewellery have been developed over the years.
Remove a light yellowish patina from sterling silver by washing with warm water and dishwashing detergent. Rinse with clean water and dry with a soft cloth—never with a paper towel or tissue. Buff with a silver polishing cloth.
Clean off a medium coat of black tarnish by first washing as described in Step 1. Scrub with a soft baby toothbrush dipped into a paste made of baking soda and water. Rinse under running water, dry with a soft towel and buff with a silver polishing cloth.
Eliminate heavy tarnish from silver by inducing a galvanic action between aluminium and copper oxide. Cover the bottom of a heatproof glass dish with a layer of aluminium foil, shiny side up. Place the silver jewellery and flatware on the foil. Separate the pieces.
Add a heaped tablespoon of baking soda per litre of boiling water and stir well. Prepare enough to cover the silver. Pour the solution over the silver and leave for 15 minutes. The galvanic action will draw the tarnish from the silver and deposit it onto the aluminium foil in an action similar to electroplating. Rinse and clean the silver as described in Step 1.
Store your sterling silver jewellery in Ziploc bags. Flatten the bags to remove as much air as possible before sealing.
Don’t wear silver when cooking or baking with eggs. Chlorine, sulphur from eggs and perfume will accelerate silver tarnishing. Don’t wear silver jewellery while swimming in a chlorinated pool, and wait a few minutes after applying make-up and perfume before donning your silver pieces.