Elmer's Glass Kiln - Manual (Page 12)

Enameling
on Metal
Preparing the Copper
Enamels come in transparent or opaque. They can be
purchased directly from Thompson Enamel, P.O. Box 310,
Newport, Kentucky 41072. Their Lead Free Enamels come
ready to use. No enamel washing is required for these enam-
els.
Start with one of the many pre-shaped copper forms avail-
able, or shape and trim the copper to your own design.
1 Heat the copper on an enameling rack to about
1400°F/760°C to burn off oil or grease. Heat the
copper to just until smoke from oil or grease stops
coming off the metal and its color has changed to a
purple-red-pale green iridescence that moves
across the copper. This indicates that the grease
has vaporized. Do not fire the copper any longer than
this point. Otherwise excess fire scale will form,
making the next cleaning step difficult.
2 After the copper cools, brush any loose scale from
the copper. Use a brush or paper towel, being sure
that you do not put any grease or oil onto the copper,
such as fingerprints. Clean the copper with a 3M
Scotch-Brite® pad. This pad does such a good job
that in most cases no further cleaning will be re-
quired. Additional copper cleaning products are
available in the Thompson Enamel Catalog, includ-
ing Sparex No. 2.
It is best to clean the copper just before you decorate it. If
you wait too long to decorate after cleaning, the copper could
get dirty again.
Decorating the Copper
Counter Enameling
Most enameled pieces should be counter enameled on
the back side. This gives the piece a much more finished
look, it eliminates a great deal of fire-scale cleaning, and it
controls the chipping and cracking that can result from the
different rates of expansion and contraction in copper and
enamel after the enamel has been fired.
Counter or backing enamel, a mixture that gives a mot-
tled effect, can be used for counter enameling. Or you can
use regular enamel. Counter enamel is applied by the sifting
method described below.
When firing counter enamel, underfire it so that the fire
scale on the front of the piece isn’t too difficult to remove.
You can purchase a masking preparation from your supplier
to help prevent fire scale. You must place the piece on a stilt
when firing the other (front) side of the piece. The stilt pre-
vents the back of the counter enameled piece from sticking
to the enameling rack.
Applying Enamels
Apply enamel over a clean sheet of paper so you can pour
the excess back into the bottle for reuse. Transparent enam-
els should be applied in several thin coats. Transparent
enamels can be mixed with fairly good results. If opaque
enamels are mixed, however, a grainy effect results. The two
basic methods of applying enamels are sifting and spatula.
Sifting Enamel
Spray or brush Thompson holding agent onto the copper.
Then sift a 1/32” layer of enamel onto the copper. Use a #60
mesh sifter. If the coat is too thin, you can easily add another
coat after firing. But a coat that is too thick will bubble and
crack. The enamel must dry completely before firing.
Spatula or Inlaid Method
You can use this method to decorate a small area with
many different colors. Using a diluted solution of Thompson
holding agent, dampen the enamels just to the saturation
point, and maintain this moisture while working with the
enamels. Apply the enamels onto the copper with a small
spatula, and spread them out with a spreader to a coat of
about 1/32” thick. Lines of contact can be formed by the
spatula blade. Then spray the enamels with the holding
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