The origins of enamelling on metal are quite old, although the essential technique has not changed much since the beginning. It is a fusion of powdered glass with a metal surface. This can be a precious metal, such as gold or silver, or a base metal, such as copper and bronze. This basic method of creating decorative objects has taken various forms throughout history.

Cloisonne

This is a technique in which thin strips of metal are attached to the metal base to form small cells or compartments (cloisons means partitions in French), which contain the enamel. The cells are filled with a finely powdered glass paste which then are fired in the furnace and fuse to the metal base. When the glass powder melts, the enamel shrinks, and when it cools its surface becomes slightly depressed. Then more powder is added and fired again. This process is repeated until the enamel level is raised enough, and then the final surface is polished.

The earliest cloisonné artefacts were found in Cyprus, dating back to the 13^thcentury BC. The technique was known and widely used by the ancient Greeks, Celts, Romans and later the Byzantines. In the Far East cloisonné was especially popular in China, where it was a somewhat later development, from around the early 15^th century. The most popular and sought after early enamelled objects were created during the reign of the Ming emperor Xuande (1425-1435). In fact, nowadays cloisonné enamel is primarily identified with China, because of the prolific supply of enamel wares produced there, both for the local market and for export to Europe. They produced a very wide range of brass and bronze vessels and figures, decorated with cloisonné enamels. These vary from small wine cups, saucer dishes, bowls, vases and jars, brushes and brush rests, plaques and paper weights, jewellery and religious and decorative human and animal figurines.

Champleve

This technique involves carving the metal surface by cutting and hammering it in order to create fields to be filled with the glass powder. The item is then fired, the glass liquefies and when cooling fuses to the metal.

The earliest champlevé enamels are in fact Celtic dress ornaments and jewellery from the Roman period. The process later was employed by the Mediaeval craftsmen between about 11^th and 14^th century. In the 12^th century champlevé enamel was widely used in Limoges, setting a firm enamelling tradition for the city. The craftsmen used to enhance the enamel effect by applying foil to the background. Gold was used to produce warm hues and silver for cool shades.

Encrusted enamels, enamels in the round or email en ronde bosse. This is a very unusual enamelling technique. It was first used in Ancient Greece and Etruria in jewellery production. In this method enamel is applied to figures that were carved in high relief or to fully sculpted figures. During the Renaissance, High Renaissance and Baroque periods this was one of the major techniques in jewellery making. All types of jewellery, such as brooches, pendants, chains, rings and earrings were lavishly sculpted and cast in gold, enamelled and set with uncut or roughly cut diamonds and precious stones and enhanced with pearls. Such jewellery was not produced by one craftsman, but rather a group of artisans that included goldsmiths, lapidaries (stone cutters) engravers and enamellers. Antwerp and Milan were the two main centres of manufacture, and other important cities were Augsburg, Prague, Paris and Florence.

Basse taille

Enamelling in low relief. This technique is related to champleve enamelling. It was introduced in the later 12^th century and was used since then in Europe. In this process the intaglio design is carved or engraved on the metal surface. It is then covered with translucent enamel, and because of the graduated shading it provides a feeling of sculpted relief. The metal base used in this technique is usually silver or gold.

Plique-a-jour

This is a development of a cloisonné technique that was first used in the 14^thcentury, and then again in the late Victorian period and the Art Deco period of the early 20^th century. This method creates an effect of a miniature stained glass window because it allows the light to shine through the translucent enamel. It is created exactly as the cloisonné enamel but the metal ground is removed after completion, so it leaves a skeleton wireframe filled with translucent coloured glass. In the 19^th century plique-a-jour enamelled spoons, cups, bowls and dishes were made in France, Sweden and Russia. A lot of the Art Nouveau jewellery was created in this way by such makers as Rene Lalique, Henri Vever and Georges Fouquet.

Engine turned surfaces or guilloche enamels

From the mid-eighteenth century a new technique was employed to decorate snuff boxes and other small objects that produced a very attractive enamelled effect. The surface was rippled using a machine engine to create a patterned ground. When covered with glaze this created an attractive shimmering effect. This enamelling technique became very popular around 1900 and the workshops of Carl Faberge created some of the best known pieces using this method.

En plein enamels

This enamelling technique is a decoration on comparatively large surfaces of gold. The enamel floats on the surface of the metal and creates a layer of its own, rather than filling carved and separated compartments. This is one of the most difficult enamelling methods and it was particularly popular in Paris in the mid-18^th century.

Painted enamels

This is a technique of free painting on small or large surfaces using enamels like oil colours. Originally the method became popular in Limoges in the late 15^thcentury. The earliest method employed produced white to grey tones on a very dark background, which was known as a grisaille palette. Originally it was used to create a cameo type figures and portraits on boxes, jars, dishes, cups, goblets and bowls. Black or other dark coloured enamel was applied onto the metal surface and fired. Then the surface was painted over with opaque white enamel which was rubbed off or thinned in places on order to create the shadowy effect. Later on more colours were added and gold leaf was used to enhance the decoration.

In Mediaeval times it was usual for enamelling craft to stay in the family where all members worked on the production. This led to a fierce competition between makers. Therefore, Limoges enamels are primarily known by their family names – the most famous are Penicaud, Nouaillier, Reymond, Limousin, Court, Laudin and Courtry. And from around the 1530’s it became common for them to sign the pieces with signatures or punched marks. Although painted enamels were also produced in Italy and in Spain, until the early 17^th century Limoges remained the dominant centre of this art.

By the end of the 15^th century the technical problems of painting in polychrome enamels were slowly solved. Great improvements in technique were made in the 16^th century and by the 17^th century enamels were already painted in full colour directly onto a metal base. This was the time when the same technique reached China through trade and missionaries, and Chinese craftsmen started producing large quiantities of high quality enamels in Canton. To this day these are known as Canton enamels and they were mainly decorated in famille rosecolour palette.

In the next article we will be looking at English enamels and in particular at the highly collectable enamel boxes.