Have you ever taken a piece of silver jewellery out of your jewellery box only to discover that it is dull or has developed a black coating? The reason this happens is because silver undergoes a chemical reaction with the air.
Sulphur-containing substances in the air combine with the silver to form silver sulphide - which is black, so when a thin coating of silver sulphide forms on the surface of the silver it darkens it.
There are 2 ways to remove the coating of silver sulphide. One is to physically remove the silver sulphide from the surface, the other is to reverse the chemical reaction and turn the silver sulphide back into silver.
In the first method abrasive polishes are used and some of the silver is also lost in the process. In the second method the silver remains in place.
To reverse the chemical reaction, you don't need any fancy or expensive chemicals or equipment. In fact, the process can be carried out quite simply, using a few household items.
To reverse the chemical reaction without removing any silver, you will need:
- A tarnished piece of silver
- A heatproof dish large enough to emmerse the silver in (ideally a pyrex or similar dish)
- Aluminium foil to cover the bottom of the dish
- A kettle or pan
- Enough water to cover the silver in the dish
- Heatproof gloves (oven mits)
- Baking soda (bicarbonate of soda) - approx 1 teaspoon per 500ml water
First line the bottom of the heatproof dish with some aluminium foil. Then set the tarnished silver object on top of the foil, making sure the silver touches the aluminium.
Sprinkle the item with baking soda.
Boil the water in a kettle or pan.
Pour the boiling water into the dish, completely covering the silver. Beware - the baking soda will fizz when the boiling water is poured on it so it would be advisable to set the dish into a sink or bath first! Also, please ensure that the dish you use is deep enough to allow for the water so that is doesn't spill.
Almost immediately the tarnish should start to disappear. If the silver is only lightly tarnished, all of the tarnish will disappear within 5 - 10 minutes. If the silver is badly tarnished you may need to repear the process.
You can use the heatproof gloves to gently shake the dish to ensure that all of the baking soda dissolves in the water and that it gets to every part of the silver item's surface.
This method works because aluminium has a higher affinity with sulphur so it helps to reverse the chemical process that caused the tarnishing.
There may be a slight salty residue on the item after the process is complete. This can be removed by rinsing the item in cold water and gently drying with a soft cloth or piece of kitchen towel.
For more information and pictures visit www.natalinasjewellery.co.uk.