Enamelling Enamelling is the process of fusing powdered coloured glass onto a metal surface. This is done by putting both the metal and the powdered glass under high heat, this melts the powdered glass and causes it to fuse with the metal creating a hard, durable coating . There are many different techniques. There are four different types of enamel: Transparent – these allow the underneath pattern or metal to show through. Opaque – these conceal whatever is underneath them. Translucent – this conceals whatever is underneath but allows some light to come through. Opalescent – these are semi opaque. All of them come in many different colours.
Firing The process of firing a piece of jewellery that is being enamelled is quite a delicate process. Pieces of jewellery are fired in a kiln or furnace . The piece is placed on either a wire mesh or trivets. Firing temperatures range between 1300°F and 1600°F, however most common firing temperatures are between 1450°F and 1500°F. Enamellists know how the read the colour of the temperature: Dark red is roughly 1300°F, Cherry red is between 1400°F-1500°F, Light orange/red is between 1550°F- 1600°F, orange yellow is over 1600°F. A piece of jewellery goes into the furnace for only roughly a minute or so, obviously bigger pieces may take a little bit longer to fire properly. There are various stages of firing.
Cloisonné French for ‘cloison’ or ‘cell’. In this technique metal wires generally silver are bent into different shapes to create a design . These thin wires are used to create raised barriers and thus filled with powdered enamel and then fired in the furnace . One of the most well known cloisonné eras was the Byzantine Empire (6th century AD). This was the setting for gold cloisonné pieces with religious themes. Cloisonné enamelled plaque – Byzantine Empire
BasseTaille French for ‘low cut’ This technique is when the metal background has a pattern created on it before enamelling. The patterns can be created using many different types of methods such as etching, roll pressing, creating hammer marks , or engraving. Transparent or translucent enamels are used over the pattern in order to show the pattern through the enamel.
Champlevé French for ‘raised field ‘ This technique is done by first etching or engraving the background and then inlaying the enamel in the depressions of the metal while still leaving some of the metal exposed. This technique is most often used as an economical alternative to cloisonné. It is therefore most often used on larger pieces.
Plique-a-Jour French for ‘membrane through which passes the light of day’ or ‘against the light’ The technique resembles a miniature stain glass window. This technique is much more delicate than other enamelling techniques as it has an open back in which the light flows through. This technique is done two ways: Surface tension enamelled – this has two different types of metal construction, first is pierced and second is filigree or skeletal framework. Etched enameled – this technique is done the same as cloisonné however once the piece has been finished the backing which is generally copper is then etched away.
En RondeBosse French for ‘in rounded relief’ Encrusted enamel This technique is done by covering 3D objects or high relief surfaces with enamel. There are technical difficulties using this technique such as roughing the surface enough in order to allow the enamel to hold on a curved surface properly.
Limoges This is the technique of ‘painting’ the enamel onto a surface. Different enamels are painted next to each other without the use of any seperations such as in cloisonne or in champleve. The object is covered in a layer of white opaque enamel, then fired. After this the piece is then gradually covered in coloured enamels which would require different firings.
References http://arts.jrank.org/pages/9611/Enamel.html The Art of Fine Enameling by Karen L. Cohen