Oxidising is a process jewellers use to give their silver a rich black colour. It completely changes the character of a pieces from light and bright to dark and brooding.
Oxidisation is achieved using sulphur based solutions. The silver reacts with oxygen and sulphur to create a layer of dark silver sulphide over the surface of the piece. This process will occur naturally over time to all silver, it will react with oxygen and sulphur in the atmosphere and tarnish to a dark colour. In oxidising our work we are essentially super tarnishing it. In fact the process is often used to make new jewellery look older.
Whatever method you use for for oxidising, whether you seal it or not, it isn't a hugely durable finish. Silver is a soft metal and when pieces are worn, especially rings and bangles, the surface abrades away and will take the oxidised finish with it. Fortunately it's pretty easy to re-oxidise silver jewellery. Just make sure the surface is thoroughly clean and follow the steps below.
Using a commercial oxidising solution.
Our favourite commercial oxidising solution is Platinol. There are lots of others available and, as ever, we recommend trying a few and seeing what works best for you.
There are two ways of applying the Platinol. Using a fine brush or cotton bud to achieve a precise application in small areas or immersing the piece in a diluted Platinol solution to oxidise the whole surface.
Which ever method you are using, wear gloves and eye protection and work in a well ventilated area. Platinol is not people friendly so follow all the safety guidelines on the bottle.
Before you oxidise you work make sure the surface is as clean as possible. Ideally pickle for 5 -10 mins first or wipe down with isopropyl alcohol. Once clean, don't touch it with your bare hands as oils from your fingers can stop the oxidising process.
To oxidise a precise area: Clean the piece thoroughly and hold in a pair of plastic tweezers. Take a fine brush or a cotton bud and apply a small amount of the neat solution to the area you want to oxidise. We prefer a cotton bud as the Platinol can sometimes cause the glue in a brush to degrade and the bristles fall out. Work quickly so you don't build up too thick a layer or oxidisation. If it's too think it will flake off again. The oxidisation should happen almost instantly so rinse quickly in large amounts of fresh water.
To oxidise an entire piece: Fill a small, heatproof container with freshly boiled water (using all the care attention required to not scald yourself or others). Add a few drops of Platinol and immerse the piece in the solution. The oxidisation process will be a little slower than using the neat solution but by using heat from the boiled water we can speed up the reaction, move the piece around and in and out of the solution using your plastic tweezers. Once it has reached the desired colour rinse in plenty of fresh clean water.
Some jewellers 'neutralise' the piece in a solution of bicarbonate of soda and water. The Platinol is not acidic so this isn't strictly necessary but won't do any harm. The important thing is to rinse as thoroughly as you can.
Using a natural oxidising material.
There is enough sulphur released from a boiled egg to achieve oxidisation on your silver jewellery. It's a more natural, environmentally conscious and safer way of oxidising but it is slower and slightly less exacting.
This method is more suited to oxidising an entire piece as it's difficult to achieve a precise application but it's relatively easy to abrade the surface back to a polished finish once its been oxidised. Because the amount of sulphur is less than in a commercial solution it takes longer to achieve a strong colour and more care should be taken to make sure the metal is properly clean and prepared. See above for details.
Boil your egg for about 10 minutes - you want it really well cooked.
As soon as you remove it from the pan, place it in a small Tupperware container or food bag and crush it finely, shell and all. Work quickly, the initial heat will help the process get started.
Add your silver, trying not to have too much of it directly against the egg or the container. You want the sulphur in the air around the piece to react with the surface. Put on the lid or seal the bag and leave in a warm place for 2 - 5 hours. Don't be too tempted to peak as you'll release sulphur and reduce the chance of an even finish.
Once oxidised rinse with plenty of fresh water and a soft brush to make sure there's no egg left on the piece.
Sealing and finishing
Once you have achieved a nice oxidised colour you can leave the surface as it is or rub it back on the high points to reveal texture or enhance the shape. If you polish an oxidised surface to vigorously you can remove the oxidisation so be gently. A burnisher can work well to bring up a shine in small areas.
Some jewellers use a lacquer or a wax ( we like renaissance wax) to prolong the life of their oxidised finish. While this can help it last longer it also makes re-oxidising more difficult as all the wax must be removed before the piece can be re-finished. We prefer to give the wearer some good care instructions (no polishing, don't wear to swim, clean, exercise or shower) and a realistic expectation of how long it should last (depends on how well they follow the instructions). We also recommend makes offer a free re-oxidisation service and allow customers to return pieces to be refinished as required. The softness of silver means any applied finish with weather as the the piece is worn.
A selection of oxidised pieces made by Alys Power.