Friday, 11 January 2013

Process of Enameling in Jewelry Making

Porcelain mortar and pestle with lump enamelProcess of Enameling in Jewelry Making is a unique and historical way of using color to enhance your work. Enamels are a mixture of silica, lead oxides, salts of soda, potassium and boric acids, which fuse to a copper, steel, silver, or gold surface when they are fired in a kiln.

Enameling is time-consuming. Each stage of the making of the piece has to be related to the enameling process, and the correct preparation of a piece that is to be enameled is essential if the results are not to be disappointing.
 

Type of enamels for Jewelry Making


Enamels are usually supplied in lump or powder form; they are occasionally found wet mixed. All enamels should be stored in airtight jars. Lump enamels have a longer shelf life than the powdered form, but powdered enamels take less preparation before they are applied to the metal. Enamels supplied in wet mixed form are painted directly onto the metal; they can also be screen printed onto larger areas.

There are three types of enamel in jewelry making: transparent, opaque, and opalescent. Transparent enamels depend on the texture or brilliance of the background metal, which is clearly visible, for their own reflective brilliance. Opaque enamels hide the underlying metal, but they have a brilliance of their own.

Hold the pestle firmly and use a rotating movement to grind the enamel. Push down as you work and continue until the enamel is really fine. Opalescent enamels have a slightly milky appearance, and some of the background metal is reflected through them. Opalescent enamels have to be fired at very precise temperatures if they are to look their best.

A material known as flux enamel, which can be in either lump or powder form, is frequently used as a first coat or undercoat on standard silver and copper. A transparent flux coat helps the subsequent enamel to retain its color and brightness in further firings. Fluxes can also be used as an "over-flux" that is, as the last, clear transparent coat on top of either a transparent or an opaque enamel to give additional depth to a piece or to "hold" a particular color that might darken if a further coat of color were added.

Painting enamels in jewelry making are very finely ground and mixed to a smooth paste with a medium such as lavender oil. They can be painted directly on a metal surface and then covered with a clear flux for firing or, more often, they are painted onto a background of opaque enamels, with the colors being built up slowly over many firings. The final result is similar to miniature oil or watercolor painting.

Preparing enamels for Jewelry Making


Before use, enamels must be finely ground, and the water used to wash the grounds must be completely clear before the enamel is transferred to the palette. Any remaining cloudiness will result in cloudy enamel. Distilled water should be used for the final rinse.

Placing wet enamels in Jewelry Making


Powdered or ground enamels
Because the metal onto which you will be laying the enamels has been thoroughly cleaned, you must take care that it does not become dirty again. Hold the edge between your thumb and index finger, and use a small spatula or the quill end of a feather to scrape a small amount of enamel out of the palette into or on the metal. Spread it out as smoothly as possible so that no metal is visible and the enamel forms an even, fine layer. Gently tap the edge of the piece with the handle of the spatula to help the enamel spread and settle.

If you want to lay a second color close up against another, dry the first color by holding the corner of a piece of absorbent tissue to it to draw off the water. When you lay the second color, you may have to let a little water transfer to the first color, but this will help in the laying. When you have applied a thin coat, the piece must be allowed to dry completely before it is fired. Place it on a wire mesh support on top of the kiln to dry.

If you are placing colors without a flux base, it is better to fire the different colors at the same time to avoid the firestain that might occur on the exposed silver if only one color were fired at a time.

Firing enamels in Jewelry Making


Leave it to cool, then fill the areas with one color. Because this piece has a base coat of flux, it is easier to fire one color first, then apply a second color and give the piece a second firing. Clean up the edges of the first color with a moist paintbrush before applying the second color. Most enamels are fired at temperatures between 1380-17400. Hard enamels are fired at the top of this range, while soft enamels are fired at 1380-15000. The time taken depends on the size of the piece and the thickness of the metal used.

Hold the enameled piece at the mouth of the kiln for a moment or two to make sure that the enamel is dry, then place it in the kiln. Remove the piece as soon as it has a slightly "orange peel" appearance. Leave it to cool on a rack.

When the piece is cool, apply a second coat of enamel and fire as before. The enamel should look smooth and glossy after the initial firing.

Apply several thin layers of enamel rather than one or two thick ones. This will allow you to control the color and makes cracking less likely.

Articles to be enamelled should be placed on steel supports or on wire mesh trays, which you should place in and take out of the kiln with a long firing fork. Protect your hand with a protective glove.

Counter enamel in Jewelry Making


As enamels are fired onto the front of a piece of metal, stresses build up in the metal that, unless balanced, will force the metal to curve toward the center of the enamel. This can be prevented by applying a coat of enamel, known as counter enamel, to the back of the piece. The counter enamel is applied either before or after the first coat of enamel is applied to the front.

When it is cool, hold the piece under running water and rub it level with a carborundum stone, which is rubbed horizontally across the piece until the enamel is level. Use wet and dry sandpapers, wrapped around the carborundum stone, still with the piece under running water.
Counter enamel can spoil the appearance of the back of a piece. This can be overcome by setting the enamel piece as you would a stone so that the back is hidden. Alternatively, the metal used for the piece could be thicker than would normally be the case to prevent it from curving - for example, if the depth of the enamel for a piece of champlevé enamel was 1/100 inch, the silver could be 5/100 inch thick.

The kiln in Jewelry Making


Kilns can be either electric or gas-fired, and they range in size from 2 x 4 x 4 inches to 12 x 26 x 26 inches. A gas-fired kiln, which can run on natural or propane gas, is quick to reach the required temperature and, because the heat is reducing rather than reflective, metal is slightly less prone to oxidization. Most gas-fired kilns have a regulator or a pyrometer.

Electric kilns take longer to heat up. They can be fitted with either a regulator on a 1- 10 dial or with a pyrometer, which shows the exact temperature of the kiln.

If your kiln has neither a regulator nor a pyrometer, you will be able to assess the approximate temperature by the color, and when it gets too hot for firing, turn it off for 5 minutes until the temperature has fallen to the correct level.

Applying painting enamels in Jewelry Making


Place a small amount of powdered painting enamel on a glass tile about 4 x 4 inches next to a few drops of lavender oil and use a flat spatula to mix the oil into the powder. Press down the mixture to make a smooth paste.

Any wires that do not sink into the flux can be gently pushed down with the side of a burnisher. Apply the enamel with a fine sable paintbrush. When you are painting onto opaque enamel, rub the surface of the enamel slightly with wet and dry papers to make a matte surface. Build up the colors gradually. You will find that at first they tend to fade into the background, and soft colors - red, for example - should be left until all the hard firings have been completed and the temperature of the kiln can be lowered.

Painting enamels, lustres, and lining enamels must all be absolutely dry before firing. Leave them on top of the kiln until the paint looks whitish, then hold them at the mouth of the kiln so that any remaining oil evaporates.

Place the piece in the kiln and remove it when the painted enamels gloss. These enamels fire quicker than ground enamels. As the picture is built up and more colors are added, the piece will have to be fired several times. Painted enamels are usually covered with a soft over-glaze flux, which not only gives a protective coating but also helps to create a sense of depth.

Preparing the metal for Jewelry Making


Metal that is to be enameled must be scrupulously clean. Any soldering must be completed before enameling starts, and if hard enamels are being used, you might use enameling solder; otherwise, use hard solder. After annealing or soldering, the piece must be cleaned. Bold it under running water and rub it all over with a glass brush until the water stays smoothly all over the surface instead of running into globules. Keep it in distilled water until you are ready to begin enameling, when it can be dried on a paper towel and then licked - yes, licked - to make sure it is perfectly clean and neutral.

Finishing a piece in Jewelry Making


When you have applied the correct amount of enamel and it is level with the cloisons or metal surrounds, the enamel must be smoothed and refired to give a neat, flat surface.

The separate colors can now be placed in the cloisons. If any color strays into the neighboring cloison, lift it away with the tip of a moistened paintbrush. It is easier to remove it now than later on.
When ills cool, hold the piece under running water and rub a fine carborundum stone to and fro over it until the enamel is level. Grades 280-400 of wet and dry sandpaper can be used under running water to give a finer finish. Dry the piece and check that the enamel is smooth. Any low areas can be filled with the appropriate color and the piece refired. If the refilled areas need smoothing down, this is done now so that the enamel is completely level for the final "flash firing," which should be done at a slightly higher temperature and more quickly than previous firings.

Enamels can also be left matte, which means that they do not need the final flash-firing after rubbing down with fine wet and dry sandpapers.

Test piece for Jewelry Making


Always fire a test piece first. Use a piece of properly prepared silver, and try firing your selected colors at different temperatures. Watch to see how and when each one fires and, from the results, work out the order of firing the piece. It is a good idea to keep the results of each of your samples as a reference. Fire colors direct onto silver and on top of a clear flux, and onto silver and gold foil to assess whether you need to use flux on your piece.

Enameling techniques  in Jewelry Making


There are approximately seven different types of enameling technique, including painting.

En bosse ronde 


Apply enamel directly to the surface of the metal, which can be flat, domed, or repoussed.

Champlevé


This French word means "level field," which is exactly what the enamel becomes when it has been applied in layers until it is level with the surrounding metal.

After the layers have been applied and individually fired, the final layer should be fractionally higher than the edge of the piece. Rub it with a carborundum stone under running water before giving a final flash firing.
Depressions in the metal are made by etching, photoetching, engraving, or chiseling, or by soldering a pierced sheet about 1/64 inch thick onto a solid sheet of the same metal that is at least twice as thick. Thin layers of enamel are placed in the depressions until they are just above the surface of the metal. The enamel is then stoned to the level of the metal before flash firing.

Cloisonné


The word cloison is French for "cell," and in this technique cells are made by bending flattened cloisonné wire to make a pattern, either to fit depressions, as in champlevé, or to be placed directly on the metal as in en bosse ronde.

The wires can be soldered to the metal, but you must be careful not to let any solder show through transparent enamel. It is more usual to fire a layer of flux first, place the bent cloisonné wires on the flux, holding them in position with a little Klyrfyre Glue, and then fire them in place. The wire should be as fine as possible because thick cloisonné wire can look heavy and unattractive.

The cloisons are filled with enamel, as in champlevé, but take care not to rub down the cloisonné wire enamel too soon. Little pieces of wire may get embedded in the enamel, and they will be difficult to remove.

Plique a jour 


In this technique, the enamel has no metal backing. A pattern is usually pierced out or it can be made by soldering cloisonné wires into the desired pattern. The wet enamel is placed in the holes and is held there by capillary action. The holes should be no larger than 1/2 inch square, and you should avoid sharp corners because the enamel will not adhere well. The pattern is either supported on steel supports or laid flat on a piece of mica.

Basse taille


Leave the piece on the top of the kiln to dry. Before you put it in the kiln, make sure that no foreign bodies have landed on the enamels. Carefully lift out any specks with the tip of the paintbrush. The French words mean "deep cut" and refer to surface decoration of the metal before transparent enamels are applied. The decoration is usually engraved, and different tones of color are achieved by altering the depths of the lines of the engraving. Transparent colors can be applied and merged according to the pattern beneath.

Grisaille


This technique uses only black and white. The base coat is usually black, onto which white is built up in several layers. The white enamels gradually blend into the black, creating various tones of dark and light gray and white.

Gold and silver foils 


Foil can be applied under transparent and opalescent enamel to give a brilliantly reflective background. The gold foil brings out the true colors of the enamels, and in addition to the reflection, silver foil can be useful if you are having trouble with firestain on silver.

Writer - JINKS McGRATH
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