CopperThe most commonly used metals for enameling are pure copper and fine
silver. The fine silver is primarily used for jewelry because of its cost,
color and the advantage of not producing a firescale coat like copper
does when it is fired. The copper is the most used metal for enameling
for many reasons: its malleability, its color, availability, and cost.
In addition, it usually maintains its shape in the firing process. The
appropriate gauge (thickness) of the metal depends on what is being made.
Most plates and vessels are usually 18 ga while jewelry can range from
28 ga for a repousse piece to 14 ga for champleve. The smaller the gauge
number, the thicker the metal. If pure copper is to be ordered from a
mill, it is necessary to specify the form, such as sheet, wire, etc.,
the gauge and the end use (enamel on copper). The Thompson Enamel Workbook
specifications are "oxygen free, high conductivity copper, conforming
to ASTM specifications B 170." I do use the 20 ga sheet copper from
a plumbing supply company for pieces up to 4 " x 10 " with about
five firings and I have not had any problems. I have not used it for more
firings because the need has not arisen. Base coated steelI have used steel in flat 12 " squares that came with their undercoat
and base coat already fired. If I overfired them so that they warped,
it sometimes was impossible to flatten them even though they were fired
and weighted many times to try to correct the warping. Copper is more
forgiving if it becomes warped. Steel needs a special undercoat before
the base coat is applied. Purchased with the base coats, the pieces only
need to be degreased with a detergent before enameling. Fine silver I usually dome jewelry that I fabricate of 26 ga or 28 ga fine silver
or oxygen free copper. Doming the thin gauge metal gives it added strength
and keeps the piece of jewelry, especially pins, from being too heavy.
I often leave the 18 ga and 20ga fine silver flat. I do counter enamel
all of my enamels. Many enamelists say that there is less probability
of the enamel cracking if the base coats have the same enamel. Cloisonne wire I like to purchase both fine silver and fine gold cloisonn? wire that
is not annealed because it is easier to make a straight line with the
wire stiff and it is easy to anneal it for intricate lines. To anneal
the wire, loosely and carefully wind it into a three to four inch roll
and fire. To test whether the wire is annealed when you take it out of
the kiln, bend back one end; if it stays bent, it is annealed and if it
does not, it needs additional firing. FoilsThe only foils I have used are the standard 24K gold and fine silver
and also a heavier fine silver foil known as "clutch" silver.
Although many enamelists pierce the foil, I never do, even though I have
used the full 3 " square sheets on enameled pieces. Jean Jenkins
places the foil, after she cuts it, on an anti static sheet. I cut a sheet
of foil between two pieces of tracing paper with various sized sharp scissors.
I have a 10" pair that I use for long diagonal cuts. The foil is
placed on the enameled piece with a water dampened #1 liner brush. Additional
water is added to the piece if the foil needs to be repositioned. The
water is drawn off with a paper towel by pressing down on the towel. If
the foil does not adhere to the enamel surface after the water dries,
then add at 1:2 diluted gum and wait until it dries to fire the piece.
For the first firing of the foil, I often sift about a 1/4 " circle
of soft flux on an area that has no foil. This spot of flux will tell
me when the foil is fused. If you overfire the foil in the first firing,
you will destroy it. After the first firing, I smooth the foil with a
glass brush. The foil can be fired higher after there are two layers of
transparents over it. Cleaning copper by buffing wheel If you use primarily transparent enamels, any marks on the metal surface
will show. A bright surface enhances the brilliance of transparent enamels.
To achieve the surface on copper, I use the buffing wheel. Caution: Although
I have an exhaust system, I wear a nose mask, a face mask, a shower cap
and cotton or leather gloves. To be safe, you need to know how to use
I use a 5 " cotton goblet buff charged with Lea Compound C, a greaseless
compound for copper in a metal tube. Cut off about 2 " of the tube,
remove the wrapping, and place the piece of compound in a small glass
jar with just enough water to cover the compound. The jar needs to be
tall enough for you to stir the compound after it is soft. Left overnight,
the compound absorbs the water and is soft enough to be stirred into a
smooth paste. I apply a thick coat of the compound paste to the goblet
buff mounted on the spindle of the buffing wheel. A stiff, small, metal
spatula works well for spreading the compound on the buff. I usually let
it dry overnight to a hard, crusty state. I soften the cutting action
of the buff by first giving a few swipes with a piece of scrap copper
across the spinning charged buff. You can clean over twelve 6 pieces before
the buff needs to be recharged.
You can also apply the Lea Compound C directly to a buff on a spinning
spindle at 1725 rpm by holding the open end of the compound tube again
the buff. This thin coating on the buff will dry within five minutes and
then you can buff the piece. Charged this way, the buff will need to be
recharged with the compound after a few pieces.
I buff the front of the piece first and the back second. By buffing the
front first, the finger marks on the back will be removed when you hold
the piece by the edge to but the back of the piece. If it is difficult
to hold the piece by its edge, I wear clean white cotton gloves to buff
the second side.
The Lea Compound C is stored with the cut end standing tightly inside
a small, metal, frozen juice can with a wet paper towel in the bottom
to prevent the compound from drying out. Cleaning copper in an acid bathThe first rule for using acids is ADD ACID TO WATER, NOT WATER TO ACID.
The most commonly used acids for removing firescale from copper, sterling,
and gold alloys are commercial grade nitric acid and Sparex 2, an acid
type cleaning compound in granular form. Acid diluted in water is called
a "pickle." Jewelers often say, "pickle it." The solution
can be used in a hard rubber photography tray, a Pyrex container, or an
electric slow cooker. The pickle works best when warm, but it should not
be allowed to boil. Although Sparex 2 is considered a "safe"
acid, both the nitric acid solution and the Sparex 2 will cat holes in
fabric. The weaker the solution, the slower the biting action. The recommended
solution for the Sparex 2 is 10 ounces by weight in warm water to make
a quart of solution. I have only used the Sparex 2 in the electric slow
cooker after soldering silver or gold jewelry. I do not clean the copper
with acid, but other enamelists explain how they use it and dispose of
the acid. The other rule when using an acid bath is use wooden or copper
tongs. Tongs made of iron will contaminate If a deep container is used
for the acid bath, wear special, long, heavy rubber gloves when you reach
into the tank. Cleaning copper by handEach enamelist has a preferred product for cleaning copper. Among the
ones I have used are a liquid dish detergent, a rag soaked in vinegar
and dipped in salt, and a scouring powder with a scouring pad. I prefer
Penny Brite. I have used it for over twenty years. It is a copper cleaner
with the right ph. I place a number of small pieces, or one 12 "
plate, on the wooden board across the top of a set tub. This board for
cutting vegetables at the sink, is sold in kitchen supply stores. I rub
one side of all the pieces with a scouring pad and Penny Brite, then turn
them over, clean the other side, and rinse them well. The piece is grease
free if the water sheets off (does not bead). Sometimes I wear rubber
gloves. I place each piece in the dish strainer, dry them with a cotton
towel, and if I am not coating the backs with liquid black enamel at the
time, I wrap each piece in paper. If I am ready to brush on the crackle,
I place each piece, back side up, on a bottle on the nearby table.
If the water, gum, or crackle pulls apart (coagulates) while you brush
it on, you can clean the spot with a little enamel, crackle, or saliva
to remove the grease from that small area.
Cleaning fine silverI clean fine silver in the kiln. I first put a number of fine silver,
jewelry size pieces, on trivets into a 1500 F kiln to remove any grease
or discoloration. I peek into the kiln to check whether they arc clean.
Fine silver is silvery white when clean. When the pieces are cool, I rub
one piece at a time with 000 steel wool. A piece is placed on a small
sheet of typing paper, and one corner of the paper is turned over a small
part of the piece to keep the oil from my finger off the metal. My finger
keeps the piece from moving. I rub in one direction over the face of the
piece, usually from top to bottom. The clean pieces are placed face side
down on a clean sheet of paper about 2 " apart for a base coat of
very thin crackle. I use the fine silver for cloisonn? pins and pendants.