INTRO TO ENAMEL:
Enamel is, simply put, a mixture of powdered glass and metallic oxides that has been melted and fused to a metal surface. The glass used by enamellists is crushed to a powder somewhat finer than granulated sugar but coarser than flour. This powder is applied to a metal surface (gold, silver, and copper, steel among others) by one of several methods described below. The item is heated to between 1000˚F and 16000˚F either in a preheated kiln or with a handheld torch. After a few minutes (ranging from one-and-a-half to ten minutes) the item is removed and allowed to cool to room temperature. Subsequent layers of enamel, normally of different colours, are applied. Upwards of ten to twenty firings are often required to bring about the desired results.

Enamel glass has a slightly different chemical composition than ordinary glass. The most common glass used by enamellists is a fusion of silica, soda, lime and a small amount of borax. The addition of borax allows the glass to fuse at a lower temperature, making it easier to work with.

Enamel can range from transparent to translucent or opaque. Colours are produced by adding metallic oxides into the powdered glass before firing. CLARITY, BRILLIANCE and DEPTH are qualities to look for in judging enamels.

Different types of enamels and different colours can be combined in overlapping layers to produce any number of other colours and effects. For example, a translucent yellow layered over a blue opaque would produce a green with much more depth than just using a green enamel.

VARIOUS ENAMELLING TECHNIQUES:
In addition to the basic methods there are a number of different enameling techniques employed by artists.

Cloisonné:
Thin metal wires, or cloisons, are fastened to the metal base, like fences, creating individual areas or pens for each colour. The pens are filled with layer upon layer of enamel until they are full. The piece is then polished so it will have a smooth even surface. The metal cloisons show between the areas of colour in the finished piece.

Plique-à-jour:
This method is essentially cloisonné without the metal backing. It is transparent, allowing the light of day to pass through. To achieve this effect the metal base is pierced by cutting holes into it. These holes are then inlaid with enamel. A variation of this technique involves soldering cloisons together to create a web of empty cells, which are then inlaid with enamel.

Champlevé:
In this method, rather than building metal walls onto the base (as in cloisonné~), the base itself is chiseled, etched or engraved to produce the individual pens. The effect is similar to that of cloisonné, but with champlevé larger areas of metal can be left between areas of coloured enamel. The final piece has a smooth even surface with areas of metal showing between the areas of colour.

Basse Taille:
A type of enamelling in which the artist first carves the subject in low relief, usually in silver, and then covers this with a transparent enamel which, after fusing, is level with the uncarved part. The contours and dimensions of the design show through the transparent enamel.

Limoges:
In the Limoges technique finely ground enamels are painted with a brush on to a previously fired enamel surface. This painterly approach to the medium was perfected in Limoges, France, during the fifteenth century.

Scrafitto:
A layer of fired enamel is covered with a layer of contrasting enamel. The design is scratched through the top layer revealing the base coat. A second firing sets the design.

Enamels may be further enhanced by the addition of precious and semi-precious stones such as rubies and opals. Paillons may also be used. These are small pieces of die-stamped gold or silver foil cut out in various shapes such as flowers, stats, circles, etc. Paillons are fired into the enamel surface or transparent enamels are fired on top of the foil.

Suggested further reading:

Matthews, Glenice Lesley, Enamels, Enamelling, Enamellists, Radner, Pa: Chilton Book Co., c1984
Ball, Fred, Experimental Techniques in Enamelling, New York: Van Nostrand Reinhold, c1982
Liban, Felicia, Cloisonné Enamelling and Jewellery Making, Radner, Pa: Chilton Book Co.