Enameling foils, heavier than leaf but thinner than aluminum foil, are often used for special effects in enameling. Gold and silver foil are the most commonly used. Often they are used to add more brilliance to the transparent enamel overcoat or to prevent unfavorable metal/enamel reactions but can also be used for other design purposes.
Piercing: Many enamelists pierce the foil with small pin holes in order to avoid blisters forming under the foil when it's fired. Others don't believe this is necessary with the thinner foils. I think the thicker Ginbari foil from Japan should be pierced. The easiest way to do this is to lay it on a sheet of 220 sandpaper, cover it with a piece of felt and roll a brayer or a rolling pin over it once or twice. Or fold the sandpaper in half, put the foil in between and tap with a rubber mallet. When you peel off the foil, hold it up to a light and you will be able to see light shining through the tiny holes. Gold foil is porous by nature and does not need to be pierced.
Annealing: Annealing heavy silver foil makes it easier to work with especially if you need it to conform to a curved surface. Place it on a clean piece of mica or lava cloth. If you need to anneal more than one piece of foil at a time, sandwich them between pieces of mica or lava cloth. If the pieces of foil touch they might melt together when fired. Anneal at 600°F. to 1400°F. for a few minutes. You know that it is annealed if it drapes easily and doesn't make a harsh rustling sound when you shake it.
Manipulation: There are many ways to use foil. Often enamelists cut the foil to fit a cell in cloisonné but you can also cut it into more elaborate shapes and/or punch shapes out of it using paper punches. It is important to know that anytime you are manipulating foil you need to keep it between pieces of paper. Tracing paper works well because it is thin and you can see through it to see where the foil is placed. However thicker paper such as copy paper is better for punching. You can cut multiples of a shape at one time by layering the paper and foil. If you have difficulty keeping the layers from sliding, use paper clips, mini clips or staples in strategic locations outside of the design area to keep the layers in place. You can also decorate foil by painting or silk screening designs on it with overglaze painting enamels. The heavier Ginbari foil can even be embossed. You can use found materials like lace or leaf skeletons for the embossing plate as long as the depth of the object is no more than 1.5/64th of an inch. Or you can make your own embossing plate by bending 24 ga. round wire in the desired pattern and gluing it to a flat, non-porous platform. Or make the embossing plate by drawing a design on tooling foil, indenting the design lines and filing them with epoxy. Lay the ginbari foil over the raised line side of the embossing form, cover it with a piece of felt and roll over it with a rolling pin or brayer. Attach this to a fired enamel and fire until the enamel gets molten enough to rise up and fill the raised areas.
I save all my ginbari foil scraps to make foil “bits”. Put the ginbari foil in a blender with some water, turn the blender on high for a few seconds, pour the mixture out into a sieve, dry out the foil bits and separate them by size by shaking them through a series of shakers - like salt and pepper shakers. You can then shake them onto an enameled piece freehand or control the design outline by using a stencil. You can also wad up leftover bits of foil and melt them into balls with a torch.
Adhering: However you intend to use your foil you need to attach it to your enameled piece. Possible "adhesives" include Klyr-fire, an enameling oil, certain gold leaf sizes*, hairspray petroleum jelly, alcohol and plain water. Water has not worked for me - tiny pieces of foil tend to "take off" in the kiln and fly about. Klyr-fire or CMC can be used on a vertical surface (and with the foil "bits" described above) but I prefer to use a liquid that does not contain water such as a size or hairspray. For small cut outs I use petroleum jelly. Paint the enamel surface with a thin coat of your choice of "foil holding agent", lift the foil on to your piece with a damp brush or damp cotton swab. If the holding agent dries out and you need to adjust the position of the foil, use a brush to slip a dab of it under a corner of the foil and coax the foil into place with the brush. After drying you can smooth the foil by covering the foil with a piece of wax paper and rolling your finger over the piece.
Firing: Fire at the temperature needed by the enamels underneath, usually 1400°F. - 1500°F. for 2 to 3 minutes. The lower temperature will result in more “crinkly” foil and the higher temperature in smoother looking foil. 23K gold foil and leaf turn darker when fired but this can be remedied by covering them with a transparent enamel and refiring. Enameling over silver and 23K foil will keep them from tarnishing.
Gold & Silver Leaf: Both gold leaf and silver leaf are very thin and difficult to manipulate. Patent Leaf is lightly attached to a paper sheet and is easier to use providing you use a sticky enough adhesive on your piece to dislodge the leaf from its backing. Leaf is best used in a whole sheet or cut into simple shapes between sheets of paper. Don't try to touch it with your hands or it will stick to you! One way to attach leaf to a pre-enameled base is to paint the base with the appropriate adhesive and to lay the piece onto the leaf (rather than vice versa). If you need to handle the leaf, dust your fingers with baby powder first or use bamboo tweezers. Gold leaf will often pull apart when fired producing an interesting crackle effect. The silver leaf sometimes will almost disappear upon firing leaving a ghost like pattern. Overlap silver leaf if you would like a stronger effect. Palladium leaf can turn pretty shades of turquoise and purple when fired but it should not be covered with enamel or it will loose its patina. Leaf is so thin it does not need annealing or piercing.
* Charbonnel gold leaf size available from Rio Grande Jewelry Supply works very well with both foil and leaf including “patent leaf”. Note: not all leaf size “works” correctly when fired.
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Samples are a time consuming but necessary part of enameling. Without them we are left guessing about enamel colors and firing characteristics. A small piece of flat metal is all that is needed to make samples of opaque colors. More sophisticated samples are helpful for transparents and opalescents. First decide in which ways you are most likely to use these colors. Perhaps you would apply them directly on the metal or over flux or over white or some other base color. Perhaps you like to use gold or silver foil. Transparents and opalescents fired directly over copper often need to be fired quite hot to rid them of the reddish oxide that forms. Enamels over silver and gold can be fired cooler. Therefore I like to make separate sample tiles for each metal.
Outlined below is one way to make a 2-compartment sample on copper, silver or gold:
A-1) Coat the lower half of a metal tile with an appropriate flux. Fire as hot as necessary to melt and clear the flux. Flux on copper will take temperatures around 1500°F. to clear. Flux on silver or gold will only require temperatures around 1350-1400°F. Pickle to remove the fire scale if necessary.
A-2) Counter enamel and fire. Pickle if necessary to remove fire scale. It’s a good idea to mark the number of the test enamel on the fired counter enamel with something that will hold up to the next firing(s) i.e. painting enamel or ceramic marker luster.
A-3) Cover the entire front of the tile with the transparent or opalescent enamel either wet packed or sifted, with the fines removed or not as you choose. Fire hot enough to clear the enamel. Abrade fire scale off the edges if necessary.
A-4) If you choose you can grind the sample and flash fire it again. Keep a record of the firing temperatures and any special characteristics of the enamel e.g. acid sensitivity.
Outlined below is one way to make a 2-compartment sample on silver or gold foil:
B-1) Undercoat the entire front of a copper tile with flux or white enamel. Fire. Pickle.
B-2) Counter enamel. Fire. Print the number of the enamel on the back.
B-3) Cut out a piece of gold or silver foil to fit the tile. Adhere it to the undercoat. (I like using “gold size” for this but some people use Klyr-fire or even straight water). Dry and fire.
B-4) Follow steps A-1, A-3 and A-4 above.
The "fines" are the tiniest enamel particles. I call the grains smaller than 200 mesh "fines". Fines may cause your transparents to be cloudier and your opaques to have a mottled appearance and may even lead to pitting in the enamel. You should be the judge of whether you remove the fines or not. Fire a test of the enamel just as it comes from the jar. If you are happy with the result you need not remove the fines.
If you decide to remove the fines there are two ways to go about it. You can wash them out or sieve them out.
Washing: Put the enamel in a jar with a lid if there is quite a bit or in the bowl of a spoon if there is only a little. Add water and shake the jar or swirl the enamel in the spoon. Let the larger grains settle for a second or two and carefully pour off the cloudy water. I pour the cloudy water out through a coffee filter rather than down the drain. Continue washing until the water is clear. Only wash the amount of enamel that you think you will need that day. Enamels start to deteriorate once they are wet so don't let them stay damp for longer periods of time. If your enamel does start to deteriorate grinding it in a mortar and pestle will make it better but will not restore it completely.
Sieving: Use a sieve to "grade sift" your enamel. I use a 200 mesh sieve with caps on the top and the bottom. Keeping the enamel covered while you are shaking the sieve will help keep the enamel powder out of your body. Wear a mask and use ventilation to draw the enamel away from you if it is available. Use the enamel that stays in the sieve. The enamel grains that fall through the sieve are the "fines".
I use the washing method when I will be wet packing and the sieving method when I will be dry sifting.
If you want to make doubly sure that the fines are removed you can sieve the enamel first and then wash it.
In a future article I will give you some suggestions for using enamel fines.
Cloisonné wire is commericailly available in copper, silver and gold. Traditionally, cloisonné wire is thin, flat wire. However round wire and twisted wire have also been used. If you have trouble bending your wire into the desired shapes, anneal it. Copper and silver wires have a tendency to spring back to their original form after you have shaped them. Annealing will help control this.
To anneal copper wire: wrap it in a coil and anneal it on a piece of mica or a clean (glass free) firing rack in a kiln at a temperature between 700°F. and 1400°F. Remove it and quench it in cold water. Pickle it to remove the fire scale. Pull it between a piece of folded Scotch Brite™ under running water to remove all the pickle residue and fire scale. Dry it off with a towel.
To anneal fine silver wire: wrap it in a coil, tuck in the ends and put it on a piece of mica or a clean firing rack. Heat it in the kiln at a temperature between 575°F. and 1300°F. for a few minutes. Remove and air cool. Fine silver wire does not require pickling.
To anneal gold wire: 24k gold wire is soft and may not need to be annealed.
If you store your annealed wire wrapped around a spool it will be less likely to get tangled or kinked. If you need to straighten out a length of wire, hold it taut, one end in each hand and run it over the edge of a table or grasp each end with a pair of pliers and pull in opposite directions at once. At this point the wire is ready to be bent into the shapes desired.
Note: You may have better luck making straight line figures e.g. squares or right angles with un-annealed wire.
PREPARING METALS FOR ENAMELING
Preparation Of Copper & Tombac*
When buying copper and tombac, ask for types suitable for enameling. Soft, electrolytic copper is used by most enamelists. Transparent colors are more "true" on tombac but there is some concern that large objects are more apt to chip and that tombac can not be fired as many times as copper. However, I have had no trouble with jewelry sized pieces.
Dark transparent colors can be lightened by first applying a layer of flux on these 2 metals. "Warm" colored transparents most often require a flux (colorless transparent enamel) undercoat on copper because they will turn muddy directly on this metal. This undercoat is not usually necessary with tombac.
To prepare these metals for enameling, first anneal them at ≈ 1300° - 1400°F., water quench and flatten or dome the metal. Pickle to remove the firescale. Rinse in running water and make sure that water sheets rather than balls up on the surface. Burnish with a glass brush. The metal is now ready to enamel.
Some enamelists dip the metal into a "bright dip" if they plan to use transparent enamels. USE EXTREME CAUTION! Bright dip is a mixture of 36 Bé Nitric acid and .1- .2% common salt. Pickle the metal in this solution for a short time, just until it begins to turn yellow. Rinse and towel dry. Place the clean metal in the kiln and remove it when it starts to turn iridescent. Let it cool and apply enamel.
*Tombac is also known as gilding metal and copper alloy #210. You may find that it is a little harder to buff this metal.
The Preparation Of Fine Silver
Anneal fine silver at about 1250 - 1300°F., then cool. Brush it well under water with a bristle brush and polish with a glass brush.
NOTE: If the fine silver sheet has been soldered, it should be treated as sterling silver (see below).
The Preparatiion of Sterling Wilver
“Depletion gild” before enameling: Anneal sterling at about 1250 - 1300°F., then cool. Pickle it. Dip it into a soda solution. Rinse it. Then anneal it again while it is wet. Repeat this sequence until no more fire scale results from the annealing. Polish it with a glass brush and water and make sure that water sheets over the surface. Dry it.
Preparation Of 24K Gold
Anneal 24K at about 1075 - 1125°F. Cool. Brush the gold under water with a bristle brush and polish it with a glass brush.
NOTE: If the piece has been soldered it should be treated as a gold alloy (see below).
Preparation of Gold Alloys
“Depletion gild” before enameling: Anneal the alloy at about 1075 - 1125°F. Air cool. Pickle it in a bath of 1 part water : 1 part sulfuric acid : 1 part nitric acid. Dip the object in a soda solution and brush it. Heat it again while still wet and anneal it slightly. Repeat these steps three times for 22 - 20 Karat and 4 - 6 times for 18 - 14 Karat.
NOTE: 14 Karat is difficult to enamel. Burnishing before enameling is sometimes helpful.