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Enameling Copper Balls
by Edmund Massow
from Volume 19, Number 4, October 2000
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Anneal the copper ball to
remove grease which may be present. Anneal until the copper
color changes to a light gold (at about 300 degrees
Celsius). Remove and let cool. Pickle the copper ball
in a 10% H2SO4
solution or in a solution of 50 grams Alum in a 0.5 liter
water. The solutions may be heated to 50 - 60 degrees
Celsius. The Alum solution works very well. It is not
so sensitive to iron traces and is safer than sulphuric
acid! I prefer it in my workshops.
Kay Whitcomb recommends not to enamel
the inside of 7/8" heavy wall balls. If I make my own
balls, the wall thickness is thinner and sometimes the diameter is
larger. For this reason I also enamel the inside (self
evident before polishing the outside of the balls!)
If you want to do so, make a thin
slurry of one of the "Thompson" liquid enamels.
Fill a syringe (I think your doctor will give you one) with this
slurry and fill the inside of the ball. It is a good idea to
warm up the ball a bit, because the slurry will stick better to
the inside wall. Let the surplus run out. Dry the
enamel* (one fire can be saved by going directly
here) and fire the ball. The inside need not be
completely enameled. It suffices that the greater part of
the inside is coated.
When cool, put the ball into the
pickling solution until all copper oxide is dissolved. Wash
the ball in hot water to remove any solution traces.
In the meantime, prepare a pair of
'cross-tweezers' to hold the ball when dipping it in liquid
enamel. If you don't have such 'cross-tweezers', you can
make a similar tool of stainless steel wire (see Figure 1).
Use a wire of about 1 mm dia. or a bit stronger and a length of
about 20 inches. Wrap the middle of the wire around a
5/8" dia. round wooden dowel or other round tool to make a
loop. Twist to form a section about 1-1/2" long.
Continue as shown, running both ends through the loop and forming
the jaws ending with pointed prongs about 3/8" long to go
into the ball. Flatten the loop to provide stability to the
jaws.
If you want to get really transparent colors, you should polish
the metal surface of the ball now. It is a bit difficult,
but you can do it. Do not use greasy polishing cream.
Polish only with non-greasy polish, glass brush, or a similar
material. If you have the facilities, polish with water and
cerium oxide with a hard felt wheel. Wear cotton gloves
during polishing.
I use Thompson's BC-303L (medium
fusing clear transparent) for the base coat. Mix well and
pour enough into a container to cover the ball when
submerged. (To check the correct consistency of water to
liquid enamel, insert a dry finger into the liquid enamel and then
remove. The enamel will drain first and then three drops of
liquid enamel should drop off your finger, no more no less.)
*Place the ball into the special tweezers so the
points are in both holes. Warm the ball to a temperature of
120 - 140 degrees F (50 - 60 degrees C). Dip the ball into
the enamel, submerging it completely. Remove it, allow the
surplus to drip off, rotate or turn your wrist to obtain an even
coat. Hold near the open kiln door to dry. It may be
necessary to continue rotating or turning until the enamel
'sets'. A thin coat of flux can be sifted on to hasten the
'setting up'.
After drying, insert a stainless steel
wire through both holes of the ball, put it on a trivet and fire
(see Fig. 2). It is better to underfire slightly than to
overfire.
If the enameled ball's surface isn't
completely covered, put the ball again in your pickling solution (sulphuric
acid or alum solution) until the scale is removed. Clean the
ball, taking care that the inside of the ball is free of any acid
or solution, because otherwise you'll get unpleasant fumes during
firing. Recoat as above and fire again. You can repeat
these steps until you get a faultless enamel surface.
For cloisonne, use round wire of about
0.5 mm. It is better to use short lengths than long
ones. Wires can be shaped with the appropriate size hole in
a dapping block. To hold the ball in position, I turn a
screw, which is about 1-2 mm thicker than the hole, in one of the
holes. The other end of the screw I clamp in a 'third
hand'. The ball is well fastened and you can turn it in any
direction. If you want to glue wires to steep surfaces
(vessels, tubes, etc.) or as shown here on the ball's surface, it
is advisable to roughen up the enamel surface with an alundum
stone or diamond file. The glue and wires will not slip so
easily on this rough surface.
Some people glue and fire the wires on a ball in multiple
steps. I glue all of them in one step. Use a stronger
glue than usual, such as Thompson's Blu-Stic. Some enamelers
have worked successfully with contact glue such as the German
brand name 'Pattex' or with cyanoacrylate glue, which in German is
called 'Sekunderkleber', which means 'sticks in seconds'. I
don't like to use this type of glue because of the possible
noxious fumes that may be present during firing.
After gluing the wires and before
firing to fasten the wires, sift a very thin 80 mesh clear
transparent enamel over the surface, otherwise the wires might
fall off during firing. After a short firing and pickling in
alum solution or 10% H2SO4
to remove the scale from the wires if you use copper wires, you
now can fill the cells with well washed transparent enamels.
Put a drop of Klyr-Fire or another organic glue into the enamel
and make the mix considerably thicker than usual. Start to
fill the enamel on top of the ball.
If you have filled the cells on top of the ball, dry the enamel
with a paper towel. Turn the ball and start to fill the next
part of the cells. Do not fill the cells adjacent to those
filled before, but on the opposite side and work toward the
previously filled cells. Only at the end connect the second
enamel layer with the first. This mode of operation prevents
the first layer getting too wet and slipping. Fill the cells
in this manner until the whole ball is covered with enamel.
Dry thoroughly and fire. You probably must fill the cells a
second or third time. Do it in the same manner as before.
After the last firing you can grind and
polish the enameled surface for a smooth low gloss finish.
For a glossy finish, give it a short refire.
You can make beautiful balls (or
beads) by press forming as
described in our article in Glass on Metal, August 2000.
Enamel inside out as described above.
Using Silver or Gold Foil
If the surface of the ball has a perfect
enamel ground coat, glue little scraps of silver or gold foil to
the whole surface. To make the foil scraps, fold a piece of
transparent paper and lay the foil inside of the folded
paper. I prefer a fairly strong transparent paper which is
still transparent enough to see the foil.
Make parallel cuts opposite of the
'folding' and then crosswise cuts. You get many little
rectangular scraps. Glue the foil scraps with a diluted
organic glue (Klyr Fire or similar material) to the surface.
As glue, I prefer normal wall paper glue (1 spoon glue to 0.2
liters of distilled water). It works very well.
The scraps must overlap so that you get a closed silver or gold
cover. I make at first a lot of little foil scraps as
described before, coat one quarter of the surface with glue, pick
up the scraps with a wet glue-free water color brush and transfer
the scraps to the surface and stroke it with the brush
lightly. I make it step by step until the whole surface is
covered with foil. Let it dry very well. To press the
foil tight to the enameled surface, I roll the ball between my
hands. Wear cotton gloves and be sure that the glue is
really dry. Fire. After that you can make your
cloisonne in the usual manner with silver or gold wire.
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