Into the Fire
By Falcher Fusager
Enamels great appeal is its rich, shimmering color. But achieving that beauty requires the artist to use sufficient enamel to obtain the desired depth of color, without falling prey to fundamental laws of physics. Many articles have been published describing traditional answers to this technical challenge, especially about the champleve technique, where enamel is applied directly to the cast or shaped piece. But few have explored the newer forms, including cloisonné and its variations, which offer alternative approaches to more familiar styles. In this article, we will examine a cloisonné technique I developed.
To understand the challenges facing the enamel artist, we must begin by defining the five common techniques of enameling. These are:
Champleve, in which enamel is applied directly to the cast or stamped piece of jewelry, usually in a single layer.
Basse Taille, in which the surface under the enamel is engraved with complex patterns that create a shimmering effect through the enamel. Earlier this century, jewelers often used large complicated machines to make the elaborate patterns we often see in antique pieces, but the technique can also be done by hand. It is often combined with champleve and cloisonné.
Grisaille, in which the enamel is powdered and mixed with a very light oil, which is then used like paint to draw a design onto the metal.
Cloisonné, in which design lines are formed with wire fused to a base and the enamel is applied as a fine grain mixed with distilled water or a light organic glue called klyrfire.
Plique-A-Jour (light of day), is a technique similar to cloisonné in that flat pieces of wire are bent into shapes. In a finished piece of plique-a-jour there is no base metal on which the wires rest. This gives a stained-glass effect of seeing through the enamel.
In traditional cloisonné, as in champleve, enameling is done directly on the jewelry itself. This limits the number of enamel layers you can use, because at some point the tension between the metal and the enamel causes the enamel to crack and even fall off in places.
The tension is caused by different rates of contraction in cooling glass and metal. Enamel adheres naturally to gold or silver (and other metals as well, although not all). However, in order to melt the enamel, the piece must be heated to 1450F and then cooled. During cooling, the enamel hardens quickly, but the metal keeps contracting. This continued contraction causes the metal to pull on the hardened glass, creating tension. The enamel may crack immediately, or the tension may be left in the piece, to be released later by even a minor bump or fast change in temperature. The problem is even more pronounced if the metal is of different thicknesses in different areas.
If the layer of enamel is thin enough, it will also be flexible enough to follow the metal's contraction with only a small amount of tension, which is what makes enamel viable in jewelry. But as we can see, only a very thin layer of enamel can be used. Small amounts of "counter" enamels - enamels applied to the back of the piece that counters the metal's contraction - can be used here and there to permit thicker enamel layers, but not every location on a jewelry piece will permit the use of this technique.
So what can we do if we want our enamels to be rich and saturated in color? The solution is to create a separate piece of enamelwork, which is then set into the jewelry like a gemstone. This piece of enamel is prepared on its own metal disk of uniform thickness, with a nice thick layer of counter enamel to balance out the material during its contraction.
This is the modern American multi-layered cloisonné enamel technique. The technique builds on the work of such well-known enamel artists as the late Margaret Seeler and has been further refined in the American arts community in the last 25 years.
The method described in this article is a variation on this technique. There is, of course, more than one way to create almost anything, and this type of enamel design is no exception. But this, at least, is how such pieces are made at Magick Fusager Demski Design.
Step by Step
The first step is to select a base for the enamel design. Our choice of metal is usually fine silver, for three reasons:
1. Enamel adheres well to it;
2. It's a bright, neutral color that lets the enamels shine by themselves (gold adds color); and
3. It does not oxidize, although it does release a small amount of oxygen during firing (more about that later).
We normally select a piece of 20 gauge silver because it offers the best stability to weight ratio. For earrings, we use 22 gauge, since these are usually smaller pieces and need to be as light as possible.
Selection done, we start by creating a slight dome in the metal. This dome further enhances stability during the multiple firings required by our technique. Counter enamel is sprinkled on dry to the backside in a thickness of 1 /2 mm to 1 mm and then fired.
Next, we engrave the top surface in the basse taille technique. Any suitable pattern can be used, from continuous lines across the piece to just add reflections, to intricate designs as a decorative element. Alternatively, patterns can be applied beforehand through stamping, rollerprinting, etc.
We now cover the surface with a thin layer of clear (non-colored) enamel, called flux. This serves two purposes: It adheres the design wires to the disk, and it seals off the silver and prevents oxygen released by the fine silver during firing from reaching the colored enamels.
On to the wires that will outline the design. The best choice here is pure gold. Fine silver can be used, as can a gold-silver alloy, but these metals will release oxygen during firing, which can affect the color.
Whatever metal you choose, you will likely start with round wires, which must be rolled flat, like ribbons. These wires should have a width of .002 inch to .006 inch, and a height of .035 inch to .06 inch, depending on your design. (Thin wire will work better for small details.)
We cut and bend the wires into the shapes we need for the design by hand, with the help of tiny scissors and fine tweezers. The wire shapes are then carefully applied to the clear-enameled surface of the disk, where they are held in place with a light organic glue such as klyrfire.
The piece is now placed in the kiln again, where the glue evaporates and the wires sink into the thin layer of clear enamel. Figure 1 shows what we've done so far: Notice how the design wires stick up, creating the cloisons (small enclosed areas) for the colored enamels.
Now we're ready for the enamel. We use precious enamel, which is also called vitreous or high-fire enamel. This enamel is referred to as "precious" because it lasts "forever," just like a gemstone.
All enamel is a form of glass. Enamel manufacturers keep their exact formulas secret, but the general formula is SO2 (quartz) + Na2O, PbO, CaO. .A note of CAUTION here: Different sources has different opinions about exactly what causes burn-out in enamels. A good source for more technical information is Thomson enamel. Some claim it is caused mostly by Hydrogen. Others claim it is the oxygen as I will describe here. But know this is simply a theory given to me by a scientist along the way, and it made sense to me. It is different metal oxides that create the different colors. In solid form, enamel is stable: It's glass and the oxygen in the air can't get to it. But powdered or melted at high heat it is a different matter. Powdered enamel deteriorates over time (via oxygenation), the extent of which more or less depends on the color (i.e., what metal oxide it contains). For example, the gold oxide used in reds and oranges is particularly vulnerable to oxygenation. At the enamel's melting point, the situation gets even hairier. Many enamels burn out fast due to the accelerated oxygenation.
This sensitivity to oxygen is why it is so important that the metals in the disk and wires do not add more oxygen to the mix. Vacuum kilns are used in the dental industry, but are impractical for jewelry because of their small size, high cost, and complex operation. But ordinary kilns can be used, as long as proper care is taken. Pure metals and good insulation from the base is the key to brilliant colors when you work with multilayered enameling, which has to sustain 10 to 20 (or more!) firings.
Now we are ready to enamel. To attain true brilliance, it is important to use small grains. We use 80 mesh, named from the screen used to sift the size. This size grain looks like fine beach sand. These enamels are normally packed with distilled water (a process called wetpacking) to hold them in their place. (Wetpacking is a lot like building a sandcastle: the water keeps the grains in place while you pack them.)
Special care must be taken to pack the grains tightly because enamel melts surface first, trapping any air left between the grains during build-up. Besides creating problems during the final polishing, trapped air bubbles lower the brilliance of the enamel. The key to success is thin layers and tight packing.
Pieces can be tightly packed by lightly tapping the side of the piece with a tool, as is traditionally taught, but better results can be obtained by holding the vibrating edge of an engraver to the side of the disk. After vibrating the piece with the engraver, we soak up any excess water with a paper towel. The piece is dried on top of the kiln for approximately 20 minutes, then placed in the kiln to melt. Be sure the piece is thoroughly dried before you put it into the kiln, since any amount of water left inside can "explode" into steam and wreck havoc with carefully packed enamel.
This process is repeated for each layer of enamel. The number of layers possible depends on how thin each layer of enamel is and how tall the wires that form the cloisons are. We usually use five to 10 layers of enamel in our pieces.
The layering of the enamels gives this technique one of its real strengths - the opportunity to use shading, which can greatly accentuate the color as well as create a great feeling of depth. Shading is created by packing grains of various shades of the same color next to each other. In this fashion, you can start with clear enamel on one end and finish with a very dark enamel in the other, creating what we call a high dynamic range. In subsequent layers, the different hues are shifted slightly to overlap the colors below. (Figure 2.) When done right, this will eventually result in rich, saturated colors and smooth shadings - usually after five to 10 layers. When the enamel reaches the top of the wires, it's reading for finishing.
Final Polish & Cutting
The final polish and cutting of the enamel disk is called "stoning" in enamel lingo. It is essentially identical to stone cutting: Briefly, you follow normal stone cutting procedures, starting with a #80-100 belt on the expandable rubber drum and ending up with a nice used #600. At this point, you have a choice. You can go on and polish the piece with cerium oxide and create a wonderfully smooth surface - assuming you successfully packed the piece tightly enough to avoid air bubbles, which during polishing will become pits in the surface. Or you can finish the piece through a "flash fire" method, in which you put the piece back into the kiln at a high temperature and let just the surface remelt. This finish is less smooth than the polished finish, but the "glassy" surface is more durable and enhances the brilliance of the enamel.
We normally prefer the flash fire method because no matter how thin the layers and how well-packed the enamel, some air bubbles - and therefore pits - will be present in the polished surface, even if invisible to the naked eye. Those pits will inevitably collect dirt and "stuff" over the years, which is impossible to fully clean out and can ruin the colors if a refiring is needed later for a repair. If a piece is intended for real use (i.e. generations of wear) we recommend the flash fire finish.
And that's it. Your gem, the precious enamel, is ready for setting. Of course, this is just a rough outline of the entire process. It would be impossible to include every potential variation: enamel is an art of subtlety. Learning its entire potential demands dedication. If you are not ready to devote yourself to it, pay others to do your enamel work. Or just do it for fun! Indeed, enamelling's rewards are as rich as its colors.
What is enamel?
Enamel is a form of glass. The players are:
S1O2 = Silica, also called quartz.
K2O = Potassium Oxide.
Na2O = Sodium Oxide. (Makes glass softer.)
CaO = Calcium Oxide. (Makes glass harder.)
PbO = Lead
Glass = S1O2 + Na2O, K2O, CaO
When you replace K2O (potassium oxide) with PbO (lead), you get enamel: S1O2 + Na2O, PbO, CaO. Lead lowers the melting point and raises the refractive index.
Finally, metal oxides are added to give the enamel color. For example, cobalt oxide creates blue enamel.