Service manual

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
agent to keep the grains of enamel in place. Allow the enamel
to dry completely before firing.
Firing Enamel
1 Heat the kiln to 1450°F/787°C for most enameling.
Digital kilns: Use a Single Segment. Please see your
digital controller instruction manual.
Rate Temp.
Segment °F/°C °F/°C Hold
1 1799/999 1450/787 01.00
Note: Hold time should be the length of time you
will be firing enameling pieces. In the above exam-
ple, hold time is one hour.
Manual Kilns: Fire the kiln with the switch on High. At
1300°F/700°C, lower the switch setting to Med. When the
temperature reaches 1450°F/787°C, keep adjusting the
switch to maintain that temperature.
2 Lay the copper shape on an enameling rack. If the
part that touches the rack is enameled, place a stilt
under the copper. Some bowls or other shapes have
enameled sides that might run during firing. These
should be fired with a stilt even if the piece has a plain
bottom. Use an enameling fork to place the rack into
the kiln.
Note: Firing should take about three minutes and
requires undivided attention!
3 Look at your piece every 15 seconds by tilting the kiln
by the switch box about 1”.
4 When the copper piece appears a rosy red and the
enamel is smooth, turn off the power to the kiln. Lift
the kiln about 1” and remove the enameling rack
with an enameling fork. Lower the kiln. Turn the
power on if you want to make more enameling pieces.
5 Place the rack on a steel pad or ceramic shelf and let it
cool completely.
6 After counter enameling, you will need to clean the
fire scale off the front of the piece. A 3M Scotch
Brite® pad works well for this. Then clean it with
Thompson Sparex No. 2.
Ceramics
Pyrometric Cones
Pyrometric cones are small pyramids of clay and mineral
oxide that soften and bend when exposed to heat. They indi
-
cate when ceramic ware has fired to maturity.
Pyrometric cones come
in 1 1/8" and 2 ½” lengths.
Use the 2 ½” cones. Cones
mounted on the kiln shelf
must be slanted 8° from
vertical. They will not bend
accurately if they are
slanted to the wrong angle.
Self-supporting large
cones have the correct slant
built into the base. Stan
-
dard cones must be
mounted in a clay or wire
plaque.
The chart on page 12
shows the temperatures of
pyrometric cones.
Digital Kilns: Pro-
gram your controller to the
cone recommended for the
ceramic ware that you are
firing. Use Cone-Fire
mode.
Manual Kilns: For
small ceramic pieces, such
as figurines, fire at a rate of
about 400°F/222°C per
hour. Ceramic jewelry can
be fired even faster. Fire to
the temperature shown in
the 108°F column of the
Temperature Equivalents chart for the cone number you are
firing. (See next page.) Before deciding on the firing speed
of important pieces, test fire samples.
Viewing the Cones
During Firing
Move the kiln top
½” - 1” to see the cone
on the shelf. (Be sure
to wear firing safety
glasses and heat-re
-
sistant gloves.) Turn
the kiln off when the
cone bends to 6
o’clock. (See top
photo above.)
/11
A self-supporting cone fired to matu
-
rity. Do not be concerned if the tip is
slightly higher or lower than shown.
A “puddled” over-fired cone.
An under-fired cone.