Enamel

I

Introduction

Enamel, vitreous paste fused by heat to metal objects such as jewellery and small boxes, or to ceramics, or glass. It is chemically identical to glass, consisting of a mixture of silica (from quartz or sand), soda or potash, and lead. These ingredients are usually made opaque by the addition of other metallic oxides. This article deals with enamel on metal as an art form. For a discussion of enamel on glass or ceramics, see Glass; Porcelain.

II

Technique

In the making of enamel, the ingredients are first formed into lumps or cakes, which are then ground to a fine powder. The powder, dry or mixed with water or oil, is applied by hand to the surface to be covered. The enamelled object is then fired in a furnace until the enamel fuses with the surface. A constant temperature, usually 1000° C (1832° F), is necessary to ensure evenness in the enamel. Five main types of enamelling have developed: champlevé, cloisonné, basse-taille, plique-à-jour, and encrusted, several of which may be used on one piece. Enamel can also be painted.

A

Champlevé

Champlevé (French, “raised field”), enamelling is done by scratching or etching a metal surface, usually copper, leaving hollows or troughs with raised lines between them. The hollows are filled with pulverized enamel that is then fired. The hard-finished enamel is subsequently filed down until the glossy surface and the metal surface can be polished simultaneously, with crocus powder and jeweller's rouge.

B

Cloisonné

In the cloisonné (French, “partitioned”) process, very small partitions, or cloisons, consisting of thin metal strips are built up on the surface of the metal. They may describe a pattern and are fixed to the surface by solder or the enamel itself. The partitions are filled with pulverized enamel, and the subsequent procedure is the same as for champlevé. The cloisonné technique is usually applied to silver, although gold or copper may also be used as bases.