Slaving over a hot kiln
Aug 29, 2011
Well it didn't feel like slaving but there was certainly a lot of hovering anxiously by a kiln heated to 800C in the enamelling workshop at the London Jewellery School.
Enamelling, it seems, is not an exact science. Because the firing is quick, the kiln temperature can fluctuate as you repeated open and close it which can vary the time it takes for each layer of enamel to cook. Other variables can be the thickness of your layer, moisture in wet enamelling and even the colour you choose. As a result you stand by the kiln taking nervous quick peeks and repeatedly seeking tutor reassurance until it looks right. So it is warm work.
The enamel comes in powder form (as pictured below) and the first lesson is handling it in dry form.
Thankfully we started with counter-enamelling - enamelling the back to add strength and support to your piece.
The first step is to clean your metal blank - we mainly worked in copper, the cheaper option. Professionals use dilute hydrochloric acid but on this occasion we scrubbed the blanks with a wire brush and wahing up liquid followed by the crucial stage of spitting the metal. Saliva is excellent for removing an greasy residue.
To dry enamel you place your blank on the work mat. Then you put a small amount, a spoonful perhaps, of your chosen enamel powder into a small sieve and then gently distribute the powder over the metal by tapping the sieve. You want an even coverage over the whole of the metal including the edges.
This sounds simple but the tricky bit comes when you then try to move the piece to put it in the kiln. You use a pallet knife to lift your piece on to a firing stilt (the spiky devices pictured beside the kiln below) and then put it all into the kiln using a long fork. All without spilling the powder - not that easy as our tutor proved when helping me involved dropping it.
Working on the back of the piece first allowed us to be slightly less nervous and learn about when enamel is properly fired.
The enamel we used for the backing was also less intimidating. The backing powder is made up from left over powder from dry enamelling all mixed up, creating a mottled grey effect that I actually think is very attractive.
For our first project we concentrated on dry powder using opaque enamels and stencil techniques.
Because of my tendency towards always choosing blues and purples, I decided to go for sunflower yellow.
This proved quite alarming when firing the first of the two layers. The enamel turns a strange mustard brown, but as we learnt the colour changes are normal and as the piece cools you, usually, end up with the colour you expect.
Once the second layer of base colour had cooled we moved on to sprinkling a second colour over a stencil of template.
This adds the challenge of removing your stencil cleanly and not smudging the pattern as you place the piece in the kiln. Not sure I was completely successful with this but I like the effect I achieved.
On my second dry powder piece I experimented with "sgrafitto". With this technique you use a sharp tool to scrape patterns in a third contrast layer over your base layer.
With practice you could produce interesting designs. On this occasion I stuck to some simple straight lines.
We then moved on to wet enamelling. With this you grind your colours with water and then paint them on your base using a quill - or piece of drinking straw - or brush.
There is a certain magic about wet enameling. Not only can you blend colours on the piece but when you have completed a wet layer, you tap the edge and say abracadabra. Well not quite. The tapping with a pallet knife handle for example, evens out the wet layer. Then you put a sheet of kitchen paper over your index finger and gently touch the edge of your piece - amazingly this dries the enamel.
At the kiln you move your piece in and out a couple of times to remove more moisture before firing.
With this one I also had a go at adding silver wire and sinking it into the enamel. This involves working on a piece straight out of the kiln - I can certify it is very hot.
Finally we enamelled a silver piece. Silver is a better base for transparent enamels - like the turquoise below - because the colours remain truer.
The day really gave a taster of what can be done with enamel - again I find myself wondering where I could put a kiln....