Vitreous enamel
In a discussion of
art technology,
enamel (or
vitreous enamel, or
porcelain enamel in American English) is the colorful result of fusion of powdered
glass to a
substrate through the process of firing, usually between 750 and 850 degrees Celsius. The powder melts and flows to harden as a smooth, durable vitreous coating on
metal, glass or
ceramic. It is often applied in a paste form and may be transparent or opaque when fired. Vitreous enamel can be applied to most metals.
Also, an "enamel" is a decorative object, usually very small, having an enamel coating, such as a piece of champlevé or cloisonné.
Vitreous enamel has many excellent properties: it is smooth, hard, chemically resistant, durable, can take on long-lasting, brilliant colors, and cannot burn. Disadvantages are its tendency to crack or shatter when the substrate is stressed or bent.
The durability of enamel has given it many functional applications, including: early
20th century advertising signs, interior walls of
ovens, speckleware
cooking pots, exterior walls of high quality
kitchen appliances,
cast iron bathtubs,
storage silos on
farms and process equipment such as chemical reactors and tanks for the chemical and pharmaceutical process industries.
Enamelling is an old and widely-adopted technology. The
ancient Egyptians applied enamels to pottery and stone objects. Other practitioners include the
ancient Greeks,
Celts,
Russians, and the
Chinese.
The bright, jewel-like colors have also made enamel a favored choice for designers of jewelry and bibelots, such as ancient beads, the fantastic eggs of
Peter Carl Fabergé, enameled copper boxes of
Battersea enamellers, and artists such as
George Stubbs and other painters of
portrait miniatures. Enameling was a favorite technique of the
Art Nouveau jewellers.
According to some sources, the word
enamel comes from the High German word
smelzan (to
smelt) via the Old French
esmail.
Some techniques of enameling:
*
Basse-taille, from the French word meaning "low-cut". The surface of the metal is decorated with a low relief design which can be seen through translucent and transparent enamels.
*
Champlevé, French for "raised field", where the surface is carved out to form pits in which enamel is fired, leaving the original metal exposed.
*
Cloisonné, French for "cell", where thin wires are applied to form raised barriers, which contain different areas of enamel applied above the original metal form.
*Grisaille, French term meaning "greying", where dark, often blue or black background is applied, then
limoges or opalescent (translucent) enamel is applied on top, building up designs in a monochrome gradient, paler as the thickness of the layer of light color increases.
*
Limoges, named after the town in France where it was invented, is the technique of "painting" with an especial enamel called "blanc de limoges" over a dark enamelled surface to form a detailed picture, often human figure. It is a form of Grisaille.
*Plique-à-jour, French for "braid letting in daylight" where the enamel is applied in cells, similar to champlevé, but with no backing, so light can shine through the transparent or translucent enamel. It has a stained-glass like appearance.
*Ronde bosse, French for "round bump". A 3D type of enameling where a sculptural form is completely or partly enameled.
*Stenciling, where a stencil is placed over the work and the powdered enamel is sifted over the top. The stencil is removed before firing, the enamel staying in a pattern, slightly raised.
*Sgrafitto, where an unfired layer of enamel is applied over a previously fired layer of enamel of a contrasting color, and then partly removed with a tool to create the design.
*Counter enameling, not strictly a technique, but a necessary step in many techniques, is to apply enamel to the back of a piece as well - sandwiching the metal - to create less tension on the glass so it does not crack.
Color in enamel is obtained by the addition of various minerals, often metal oxides
cobalt,
praseodymium,
iron, or
neodymium. The last creates delicate shades ranging from pure violet through wine-red and warm gray. Enamel can be either transparent, opaque or opalescent (translucent), which is a variety that gains a milky opacity the longer it is fired. Different enamel colours cannot be mixed to make a new colour, in the manner of paint. This produces tiny specks of both colours; although the eye can be tricked by grinding colors together to an extremely fine, flour-like, powder.
Some paints are called "
enamel paints". This is a commonly used, yet fanciful term, implying that an ordinary latex or oil-based
paint has the same properties as true, fired enamel.
Bicycle frames and similar steel objects are traditionally stove enamelled in countries such as the UK. The paint is baked on but the temperatures are much lower than for true vitreous enamel - approximately 200 degrees Celsius. The process should not be confused with
powder coating as the enamel paint is sprayed on "wet".
*
Cloisonné*
Nineveh*
Rostov the Great*
Silicon*
Mechanical and Physical Properties of Vitreous Enamel*
Institute of Vitreous Enamellers (UK)*
Deutscher Emailverband (German Enamel Association (DE))*
Glass on Metal Magazine Online (US)*
CIDAE Center of Information and Diffusion of the Art of Enamelling (ES)*
Society of Dutch Enamellers (NL)*
The Enamelist Society (US)
