Service manual

Firing Low Fire Glaze
Low fire glazed ware must not touch each other, the floor,
or a shelf in your kiln during firing. If this happens they will
permanently bond together by melted glaze and be ruined.
Clean the firing chamber before each glaze firing. Wipe
surfaces with a clean, damp cloth or vacuum with the soft
brush nozzle attachment of a vacuum cleaner.
Use stilts to support low-fire glazed ware during firing.
The shelf tops and kiln floor MUST be kiln washed with all
purpose, high fire kiln wash for protection from glaze drops.
Glazed pieces must be thoroughly dry before firing and
should not be fired with greenware unless both mature at the
same cone. Check to make sure that first, no two pieces of
glazed ware are touching each other, the kiln walls, the floor
or the shelf; and second, that the underside of the kiln shelf
is clean before you place it over glazed pieces. Any dust fall
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ing on your ware will cause pinholes.
You can prevent glazed pieces from sticking to the shelf
or kiln bottom by “dry footing.” To “dry foot” a piece, re
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move all glaze from the portion of the piece that will rest on
the shelf. Using a wet sponge or a piece of grit cloth, clean off
the glaze from the bottom of the ware and slightly above the
base so that it will not run down and touch the base. Dry foot-
ing should not be used for low-fire glazed pieces that will be
placed in water while used or cleaned.
During the first hour of firing, vent the kiln by placing a
½” post under the top. Wait until the kiln has cooled to room
temperature before opening the kiln.
Remove the stilts from the ware after firing by breaking
the thin film of glaze holding them. Handle with caution; the
glaze is sharp where the points touch. Remove the sharp stilt
edges by rubbing with a stilt stone or electric grinder.
Firing Porcelain Greenware
Loading porcelain greenware is similar to loading glazed
ware, since both will stick to anything during firing.
Greenware must be completely dry before firing, including
the joints on pieces that are attached. If a piece is broken be
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fore firing, mend the break but do not attempt to fire it until
the mend is also bone dry. Damp greenware or damp
mended areas will form bumps on the fired ware.
Stilts CANNOT be used to support porcelain greenware.
They would embed into the porcelain. To protect porcelain
from sticking to the shelves or kiln floor, apply a coat of high
fire kiln wash to the shelf tops and brick bottom. Then place
your ware directly on the kiln washed surfaces.
Note: Never use ceramic kiln wash in a kiln that will
ever be fired to porcelain temperatures, as the ce
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ramic kiln wash will harden at high temperatures
and be impossible to remove.
Pieces of ware that are to be used together must be fired
together, such as a box and its lid. Dry all purpose, high fire
kiln wash can be used to separate these pieces during firing.
Wet kiln wash would be too difficult to remove. Pieces likely
to warp in firing should be supported by rolls of porcelain
clay shaped to fit the objects at points of strain. Apply dry sil
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ica or high fire kiln wash to the points of contact to prevent
sticking. Before firing, the support rolls must also be dry.
Since a kiln is slightly hotter near its sidewalls, the side of
the ware next to the walls will tend to shrink more than the
opposite side. This can be used to your advantage with por
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celain figurines that tend to warp during firing. Turn the in
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clined side of the figure away from the elements so the heat
can help hold the piece straight.
Make sure cones on the shelf are clearly visible. At porce
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lain temperatures, they are difficult to see. Vent the kiln dur
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ing the first hour of firing by placing a ½” post under the top.
Wait until kiln cools to room temperature before opening it.
Firing Porcelain Glaze
Porcelain pieces that have been fired together in the
greenware firing cannot be fired together in the glaze firing.
Both pieces must be “dry footed.” Since shrinkage has al
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ready occurred in the greenware firing, the pieces will still fit
even when fired separately in the porcelain glaze firing. Stilts
must not be used to support porcelain. Porcelain softens dur-
ing firing, and stilts would embed into porcelain. Make sure
your shelves and kiln bottom have a good coat of kiln wash
before firing porcelain.
If a piece of ware had to be supported in the porcelain
bisque fire, it will stand alone in the glaze fire. The lower
temperature will prevent sagging.
Vent the kiln during the first hour of firing by placing a ½”
post under the top. Wait until kiln cools to room temperature
before opening the kiln.
Firing Stoneware
Greenware or Glaze
Stoneware is made from vitrifiable clays with a firing
range of cones 2 - 10. It has a wide range of colors and tex
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tures and is popular with the potter because of its excellent
throwing qualities. Usually the greenware is fired below ma
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turity, and on the second firing, the clay and glaze mature to
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gether to form an integrated body-glaze surface.
Like porcelain greenware, stoneware is placed directly
upon the kiln-washed shelves in the greenware firing.
Glazed stoneware must not touch any other ware and
must be dry footed before you place it on a kiln-washed shelf
or kiln bottom. Never stilt stoneware during either firing.
Glaze Testing
Make batches of uniform clay shapes, such as circles or
triangles. Each shape should have a smooth section and tex
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tured section. Glaze the test shapes. Prop them up vertically
inside a dish and fire them. Keep detailed records in a glaze
notebook. Save the test samples. They will be valuable later.
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