Enamelling On Copper
Copper has been the most inexpensive and satisfactory metal for use in enameling. The thickness of copper is measured in gauge sizes. The most commonly available gauges for enamel projects are 16, 18 and 20 gauge. (The smaller the gauge number, the thicker the metal)
Enamelling on Copper
The origins and development of technical enamelling
The transition from artistic to technical enamelling happened gradually and it was favoured by the progress in the metallurgy field brought by the First Industrial Revolution. In 1761 it was possible to enamel the internal part of a cast-iron container for the first time in history. At that time, the only method to deposit enamel on large cast-iron pieces consisted in heating to redness the metallic substrate and apply the powder enamel onto the hot surface, making it soft and adhering to the substrate. After this step, the piece was reheated in the furnace to make the enamel melt and create a smooth glassy surface. This method, also if somewhat simple, is still used for the enamelling of large cast-iron pieces, such as bath tubes.
The real turning point for technical enamelling came around the 1850 when Austrian and German chemists successfully managed to enamel the internal part of sheet steel containers. It was in these years, to be precise in 1851, that the first manual on enamelling was published, written by Moritz Vogelsang. From the beginning of the 20th century, the use of enamelled objects spread rapidly in America, gaining more and more market through the years. From the last years of World War, I onward the industry of enamel boomed and attracted expert chemists, engineers and ceramists, who played a key role in transforming the old art of enamelling in a real science.
Enamelling techniques over the centuries
Over the centuries many different enamelling techniques have been developed. In the next paragraphs, we will describe in detail the most important techniques, such as the cloisonné, the champlevé, and the émail paint.
The cloisonné technique
The cloisonné technique is the most ancient enamelling deposition method. The word "cloisonné" derives from the French word "cloison" (originated from the Latin word "clausus" the vitrification of the enamel. The possibility to use metallic strips as expansion joints allowed to create beautiful objects, guaranteeing good adhesion between the enamel and the metallic surface. The first important cloisonné archaeological findings can be attributed to the Assyrian Empire and are constituted by polychrome bracelets found in the Nimrud tombs. On this regard, it is important to underline that Assyria, around 650 BC, controlled territories in which enamelling had already existed (Cyprus, Egypt): both these clues make the hypothesis of the use of porcelain enamel by the Assyrians very realistic. From that moment onwards the cloisonné enamelling technique spread in all the ancient world, mainly following two roads: the first towards the east, along the Silk Road, the latter towards the western Mediterranean Sea. The responsible of the spread towards the east were the Scythians, an Iranian warrior people, who brought the art of enamelling to Iran, Siberia and the Caucasian area, between the 600 BC and the 300 BC.
The champlevé technique
The champlevé technique is very different from the cloisonné method, as it consists in applying the enamel powder in carvings made on the substrate and then proceed to the firing of the powder to obtain a smooth surface. This technique has been used by the Celts since the 1st century BC to decorate small bronze objects such as brooches and buttons. During the following centuries, a "Gallo-Roman" technique (champlevé on bronze) was developed and the Romans played an important role in the diffusion of bronze enamelling. The champlevé decoration process flourished again only in the last decades of the 11th century when the champlevé enamelling on copper was born in the French town of Conques.
From the Renaissance onwards
The decline of the champlevé enamelling started at the end of the XIV century, but only after 100 years it rose up again in Limoges under a different form, called "enamel paint". Enamelled objects had no more a religious character but were mainly committed by rich families as luxurious decorations objects. The technique of enamel paint consisted of using enamel as if it was painted on the substrate, used as a canvas. When we refer to enamel paint is necessary to point out that two different techniques were developed, the first called "grisaille", only using black and white enamel, the other, more general, using coloured and also translucent enamels.