Enamelling and watchmaking

There is an inextricable link between the enamel and the metal. The latter is indispensable to the former, not only in determining its composition but also as a base. This alliance found its expression in Antiquity, during the Byzantine Empire, and then in the Middle Ages, in the embellishment of a vast array of finery, clothing, liturgical and domestic items. Closely associated therefore with jewellery and goldware, enamelling naturally took hold in the new art of metalwork which, combined with mechanics, emerged in the Renaissance: Portable horology.

The applications of enamelling to horology are a subject worthy of considerable study, as illustrated above all by watch cases and dials and, to a lesser extent, by clock cases and dials or accessories such as keys and breloquiers.

Between 1600 and 1900, enamel played a dominant role, comparable only to that of engraving, in watch ornamentation. Neglected as a form of decoration of bracelet watches in the 20th century, it is currently experiencing a revival which goes to show how admiration for it has never dimmed.

In its original state, enamel is a colourless and transparent product, not unlike crystal. It is produced from a mixture (frit) of several substances: lead oxide, silica sand, potassium or sodium carbonate, lime or magnesium. They are melted at a temperature of 1400 degrees by a process known as sintering. Reduced to a fine powder, the frit is mixed with various metal oxides which determine its colours, and is then re-melted. It is then drawn from the crucible using a scoop and poured onto the metal plates where it vitrifies in the shape of slabs. Washed intermittently with water, the pieces of enamel are ground by the enameller in an agate mortar with a pestle made from the same substance. The enamel powder is mixed with water and then laid using a brush, goose feather or spatula onto a metal base, generally made of gold or gold-plated copper.

From the 19th century onwards, specialist firms would deliver enamel in lump, rod or powder form. The firms Dufaux and Millenet of Geneva were renowned for this speciality. Nowadays, manufacturing workshops are fast disappearing.

Catherine Cardinal: Splendours of enamel