Jeweller, metalsmith, enameller
Cloisonné, meaning "to partition" in French, is one of the oldest enamel techniques. The style flourished in the Byzantine Empire, throughout the Middle ages, and is favoured by many Japanese and Chinese enamel ware producers.
The most common form of the technique involves the bending of fine wires which are then fused into a base layer of enamel. The design is built up by placing the various enamel colours into the cells that are formed by the wires.
The most significant development of the cloisonné technique is Plique a jour, which has now, in effect, become another complete method. It is similar to cloisonné in that the designs are created by wire forms (or can be pierced from sheet). The only difference is that the wires have no metal backing, enabling light to shine through transparent enamel creating a stained glass window effect.
Cloisonné wires can be fashioned from copper, silver, or gold. Traditionally wires are rectangular, although round wires can be used (as demonstrated). It is also possible to forge, file and shape irregular sections of wire to fuse into the enamel for more freeform /expressive drawn effects. The wires for all methods are very fine. Rectangular wires are generally 0.2mm or 0.3mm thick and around 1.5mm deep. The round wires used in the demonstration are 0.3mm diameter. Different diameters of wire will give different thicknesses of line and different enamel depths.
The cloisonné wires should be annealed and cleaned before shaping and placing onto the enamel surface. I use 18k gold* round wire as it requires little cleaning once annealed. I prefer to use round wire as it is easy to shape and stays in place more readily, not requiring balancing the way rectangular wires do. In this exercise the enamel depth I require is quite shallow - rectangular wires allow for greater thicknesses of enamel and can be used for other effects.
(* only higher karat gold, or gold alloys of an enamelling quality should be used. Ordinary low karat golds do not enamel well due primarily to the large amounts of base metal, mainly zinc, they contain.)
Firstly as with any enamelling technique, the metal has to be cleaned. For the cloisonné demonstration, copper has been used. It's easy to clean. The main objective is that it be grease free, particularly if you are using transparent colours. The annealed metal should be wet-sanded / pumiced back to remove the oxide layer, using water with a few drops of dishwashing detergent to aid in wetting of the surface and removal of grease and other soils.
A word on acid pickling at this point. Pickling serves only to remove the copper oxides - firescale - which are formed when the metal is heated above about 650° C and does not remove grease or other soils. After cleaning the copper should look bright, and as mentioned, the main thing is that it should be grease free. If you are using transparent colours more care is needed as they will reveal irregularities in the metal surface - with opaque colours, however, you do not need to be as rigorous.
For the cloisonné sample sheet copper of 0.7mm thickness was used. When using thinner metal a layer of enamel called "counter enamel" should be applied to the back of the piece. The counter enamel I've used here is a general mixture of enamels. It acts to strengthen the piece and prevents warping of the metal. In the case of bowls or pieces that are to have both sides of the article showing, a counter enamel of a complementary colour can be used to enhance the overall effect of the piece.
Counter enamel is sieved evenly over the piece which is then transferred to a mesh and fired in the kiln. Once the counter enamel has been applied and fired all firescale must be removed and the piece should be thoroughly cleaned again before applying the flux layer to the front.
Counter enamel
Firing # 1
Firing # 2
A layer of flux is applied and fired onto the front of the piece. The wires are then shaped to the required design and placed onto the fired flux layer. Working from the illustration, the wires are cut into short sections and butted up to each other to form the design.
Basic tools are used for this - flat and / or round nose pliers to shape the wires, a scalpel to cut them and a fine paint brush to put them in place. A variety of solutions can be used to hold the wires in position until they are fired. Traditionally gum tragacanth is used although Klyr Fire ( an American product ), or enamel painting medium can also be used - anything, in short, that will hold the wire in place but burn away completely in the kiln without disrupting the wires.
It is quite possible to apply the wires without any type of gum - if they hold without it you don't have to bother. I tend to use enamel painting medium as that is what I have, and it seems to work OK.
Once all the wires are in place the piece is fired in the kiln in order to fuse the wires into the flux layer.
Forming
wire-work
Finished
wire-work
The filling of the cells at this point is the same as for the champlevé method.
The enamel is ground with a pestle and mortar into a wet paste of even particles, washed thoroughly in distilled water to clean away any impurities, suspended in water and stored in covered pots.
Enamel is applied into the cloisonné cells with a quill (or a brush if preferred) tapped gently to remove air bubbles, dried with a tissue to remove moisture, and fired in the kiln. Again, three to four thin layers are applied to the piece and fired to completely fill the cells.
First layer
applied & fired
In this demonstration a foil edge as been added to give a finish to the piece.
Fine gold foil can be cut to shape and fused onto the enamel to give a variety of effects. To apply the foil, place it on the enamel in the second-last firing to fuse it onto the surface.
Use a fine brush to stroke the foil down and position it where it is needed. For the final firing the foil must be covered with a layer of flux to seal it into the surface. When applying foil, small sections can just be placed on the enamel and fired without too many problems. However if you are using larger sections of foil, it will need to be perforated so that air and moisture trapped underneath can escape. This can be done by placing the foil over a sheet of fine emery / finishing paper and patting it gently with a soft, fine brass bristled brush.
The holes will not be immediately visible but if you hold the foil up to a light carefully you should see lots of tiny perforations. A small amount of water only on the brush ( just dampened ) is best for keeping sections in place. Gum solutions will oxidise (burn) at red heat and produce gases which might remain trapped under the foil and create pits or craters. If the foil is applied in sections, extra enamel can be added where it is needed to fill the cloisonné sections.
Karat gold foil tends to oxidise when fired but when the flux layer is added the mainly copper oxides are dissolved and the foil appears bright once more. Foils can be used not just in cloisonné, but in champlevé, painted enamel and a variety of non-traditional techniques as well.
Foil applied
Again, as with the champlevé technique, once the fired enamel has reached the top of the wires it is stoned back with carborundum stone ( or diagrit papers ) to ensure that the piece is flat and the enamel surface is even and flush with the embedded wires.
The carborundum stone is used with water to grind back the surface of the enamel, revealing the wire outlines. The piece is then rinsed with water using a glass brush in order to remove any carborundum particles and is fired again to re-glaze the enamel.
The enamel is traditionally fired to a shiny surface, although it may be given a variety of finishes. It can be under-fired to give a granulated effect or be treated with acid etchants to give a matt finish.
Finished sample
Main stages
Finished group
eNAMEL thanks Ruth for the use of her images
