Wednesday, 9 March 2011

Science: Cleaning Sterling Silver in the Home

If you have a favourite piece of jewellery made from sterling silver, here is a clever, cheap and easy trick to restore shine. We tried it on some recently acquired vintage sterling silver charms with lots of tiny details to clean up.

Some people see the tarnishing as all part of the history of the charm, and we do agree - to an extent - if we were selling our beads and charms through a retail shop where customers can handle the goods for themselves, then we would leave well alone, but for sale over the internet where a really good picture of the item is essential, then we feel there is more to be gained from cleaning (plus it makes it easier to read any hallmark or maker's mark). The silver will darken again naturally without any assistance! We would be very wary of cleaning charms with inset crystals or cabochons (the heat and the water may dissolve any glue used), and would also avoid this method for cleaning charms with Stanhopes (ultra-tiny photographic images). Enamelled silver charms should be robust enough for the process described - enamel being made of glass - but if anyone knows otherwise, please let us know!

Head to your kitchen and tear off a length of aluminium foil. Use this to line the base and sides of a glass or plastic container small / large enough to contain your piece of jewellery. Sprinkle a small amount of bicarbonate of soda (aka baking soda, sodium bicarbonate, but NOT baking powder - the latter is something else) into the bottom of this container - to cover the area that the jewellery item will take up. Put the item that you want to clean on top of the bicarbonate of soda. If you are cleaning multiple items ensure that they are not touching. Cover the item with more bicarbonate of soda (you will only need a spoonful).

Add a small amount of hot water, pouring directly over the item. You should hear a sizzling as the tarnish transfers via the liquid to the aluminium foil. Don't inhale the fumes given off whilst you are watching. We carried out our cleaning underneath an  extractor hood, so that fumes were drawn off. Working outdoors is another alternative.

Essentially what you are doing is transferring the tarnish to the aluminum, using the chemical process known as electrolysis - the same process used for silver plating base metals etc. As with any cleaning method for cleaning up sterling silver be sure to use it sparingly. Each time you clean you lose a tiny amount of the surface of the item, overtime this will create a worn look (and with silver-plated items this will mean the plating wears way to expose the base metal underneath). Only clean when really necessary, and accept that silver items will never keep that super bright look for long - but they do take a long time to become really dark.  

After a few minutes remove the item from its powdery bath and rinse clean with water. Dry and polish on a soft cloth. If tarnish remains then repeat the above instructions whilst being wary of over doing it!

The results are subtle rather than taking the charms back to look brand-new. See the change to the cup and saucer charm.

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