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The Enameling Process Sequence

The Enameling Process

Enameling is glass fused to metal at high heat. Vitreous enamels are finely ground glass, like fine sand (or even more finely pulverized and mixed with an oil or adhesive). They may be opaque or transparent; their colors come from the use of various oxides. Enamels are similar to ceramic glazes, except that, whereas glazes are in a raw state when applied to ceramics and go through chemical changes in the firing process that smelt them into glass, enamels have already been smelted. The firing process simply melts them and fuses them to the metal.

For two-dimensional work on copper, I begin with a large sheet of 99.9% pure copper, measure, and cut it using a foot-powered metal shear. Pure copper is necessary for the enamel to bond well in the firing process. The metal (copper, precious metals, or steel) must be thoroughly cleaned. Enamels are applied to the base metal using a variety of techniques. These may include dusting the enamel through a sifter; stencil; use of adhesives - gums  or oil - to bind the powdered glass for sgraffito, painting, freehand drawing or lettering; silkscreen; and other techniques. The piece is fired at about 1450 degrees F for several minutes and removed from the hot kiln. After it cools, more enamels are applied; the process of enameling, firing, and more enameling is repeated many times, producing multiple layers of images. An individual enameled copper tile - and each tile of a mural comprised of many tiles - will have been fired six to ten or more times.

Metals may be worked - etched, chased, formed, etc. - before any enamel is applied. The color of the metal shows through transparent enamels: transparent ambers are vibrant over copper, transparent blues and greens over silver; transparent reds over gold. To utilize these qualities on large-scale pieces, thin foils of silver or gold may be applied as parts of a design on copper or steel.

Porcelain enamel, formulated with very fine porcelain clay, results in a highly durable, colorful opaque surface: enameled steel is still commonly used as a coating for stoves and in industrial uses, as well as in murals.

Enameling is characterized by brilliant, non-fading colors, tremendous durability, variety of color effects depending on angle of light, and tremendous versatility - from jewelry (many people are familiar with cloisonne, which is a type of enameling), to bowls and wall pieces, to large-scale interior or exterior murals. The medium of enameling goes back two thousand years and forms part of the artistic heritage on six continents.

Stage One

Nameplate, Bare Copper

The copper tile is fired to clean the surface of any oils so the enamels will adhere. When cool, the tile is placed in a dilute acid solution to remove any firescale (oxide) that may have formed.

Acid Bath

To prevent warping when the metal and glass are heated, then cooled, the copper must be coated with enamel on both sides.  I apply an adhesive solution to the back of the tile.

A coat of enamel -in the form of glass pulverized to the consistency of fine sand - is dusted onto the back of the tile and sticks to the adhesive.  I turn the tile over and dust the clear enamel onto the front.

Firing temperatures range between 1350 and 1500 degrees Fahrenheit.

When the kiln reaches the right temperature, I place the tile, on a firing stand, inside. The piece will fire for just a few minutes.

Firing stand with tile in hot kiln.

Nameplate After First Firing

The copper tile with the first fired coat of clear enamel.

 

Stage Two

To create a subtle visual texture, I sift  translucent amber enamels through stencils.

More texture: more gold tones of enamel are sifted through a different stencil. The stencils I used for this piece are ones that I made for a previous mural project.

Nameplate After Second Firing

Variation in the background tone and texture begin to show with the fired stenciled enamels beginning to catch and reflect light.

Stage Three

I apply oil as an adhesive to the top and bottom borders of the tile. (Because the piece is already coated with glass, the oil doesn’t interfere with adhesion.) Oil is useful for applying designs since it doesn’t dry quickly like water-based glues.

Dusting opaque blue enamel onto the border.

Applying light opaque blue enamel.

Drying the oil over a hot plate.

Pouring off excess enamel.

Nameplate After Third Firing

The opaque light and dark blues define the border.  The background texture created by the stencils in the previous stage becomes more pronounced with successive firings.

Stage Four

I apply silver paillons -small pieces of fine silver foil - to adhesive on the border.

Transparent blue enamels mixed with water-based adhesive are carefully placed on the paillons. Ideally, the coat of enamel is one grain deep. This wet-inlay technique allows for precise placement of enamels in small spaces. (A quick firing  before applying the transparent enamels ensures that the paillons are fused to the enamel underneath.)

The brilliance of the silver reflects light through the transparent enamels when fired. The “relief” effect on the stenciled amber-toned background is even more apparent.

Stage Five

Another opaque blue enamel, mixed with a rice starch solution, is poured over the tile.

The tile is tilted around so the enamel solution flows over the entire surface, forming an even coating.

The tile is dried on the hot plate, then allowed to cool.

I trace my lettering design, through carbon paper, onto the dried, unfired enamel surface. I designed and drew the lettering; it is based on historic manuscript styles with some modifications for legibility.

The sgraffito process involves scratching through the unfired enamel to reveal the fired surface and colors underneath. The rice starch solution, when dry, holds the enamel tightly, is easy to draw on, and allows for precise cutting using the sgraffito technique.

Having scratched through all the traced lettering (as well as the borders that had been covered by the poured solution), I apply one more coat of transparent blue over the borders. I mask off the lettered area so no transparent enamels fall on it.

The finished nameplate cooling on broken kiln shelf fragments by my studio window after the final firing.

The nameplate combines color subtleties developed in early firings, opaque/transparent enamel qualities, and clearly-defined lettering.

For additional information about the enameling process, please visit the website for The Enamelist Society, Inc. (www.enamelistsociety.org), a volunteer arts organization founded in 1987 for the purpose of promoting the art of enameling.

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