Science: Oxidising with Eggs in the Home

We had read that it is possible to oxidise the surface of sterling silver, silver plate and copper using just the magical sulfuric properties of a humble hard-boiled egg. This intrigued us, and it was clearly going to be a safe, chemical free way to give an aged look to metal.    

For testing purposes we made a pair of silver-plated metal bead and fire-polished crystal glass earrings with silver-plated head pins, jump rings and fish hook fittings.  Something simple, light and bright in the hope that the oxidising effect would be very obvious.

Requirements:

• A hard-boiled egg fresh and hot from the pan (or two if you are oxidising a lot of pieces or a large piece)
• A shallow plastic box with a lid, large enough for pieces of egg and the metal objects to sit in it without the egg getting on the jewellery. Alternatively you can suspend the jewellery items above the egg - i.e. hang earrings on a wire.

Step One:

Clean your metal to remove any surface oils that may be lingering there. Oil will prevent the sulfur gas reaching and working with the metal.  Any copper that you want to age will need to be unlacquered. The oxidised finish on copper will be a dark brown colouring, if you want an instant blue-green patina you have to achieve this by other means.

Step Two:

It is essential that the egg used is hot. The oxidisation process can be speeded up if the metal to be oxidised is also warm - but this is not essential. Either heat your metal in scalding tap water, or use a little of the water used to boil the egg. If your piece won't be happy in a hot bath, then leave this step out.

Step Three:

Put your metal items into the centre of the box, or suspend from thread / wire.

Step Four:

Take your piping hot egg and using a tea towel or similar to prevent egg burn cut the egg into four. Cut right through the shell, no messing.  Pop the quarters into the box and slam on the lid.

Step Five:

If you have placed your item on the floor of the box, you may want to turn your piece over after 15 mins to ensure the reverse gets the same exposure. The amount of time that you leave the oxidisation process to go on for depends on the effect that you want to achieve. After 30 minutes you should be able to see a discernible difference. If you want a darker colouring you can reheat the egg in a microwave and give it another go.

If the egg does get on your metal, it will do no harm, just clean it off.

Results:

On the left are the silver earrings pre-treatment, and on the right post-treatment. We left the earrings for several hours - due to other activities and this was just an experiment - but you might prefer to keep an eye on the process so that you can halt it when the effect you want has been achieved. If you want a darker effect repeat the treatment.  We found that some of the silver-plated parts oxidised to a greater extent than others - i.e. the fish hook earwires became darker than the metal beads. You might want to test your components first before committing yourself to oxidising a large piece of jewellery with lots of elements, in case you find the uneven distribution of oxidation to be a problem.

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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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