Remember when loading to place a large (witness) cone behind each of the peepholes for each
firing so that you can monitor the progress of that firing. For an accurate reading, cones should be
placed 2” to 3” behind peepholes to avoid a cooling draft. Also check the operation of the Kiln
Sitter
® (see Kiln Sitter® operation). See Figure 3-5. For more information on cones and their use,
see the section on temperature indication.
There are variations in loading techniques depending upon the type of ware being fired. The
following are recommendations for loading different kinds of ware.
Loading Bisque
Low fire ceramic greenware pieces will not adhere to each other when fired; therefore they may
touch one another. They may be stacked and set directly on shelves without sticking. In some
cases they may be nested or placed on top of one another, if the weight is evenly distributed on
the pieces below. Do not, however, place a heavy piece upon a small piece or the weight may
cause the lower piece to warp or crack. Tile and large flat pieces should be fired flat on a shelf so
they do not warp. Slow firing is required in such cases because the shelf mass effects the
temperature uniformity across the flat piece. Strain on any delicate portion of a piece could result
in distortion. Fire bisque items with their lids in place to assure a good fit. Remember that
although low fire greenware pieces may be touching, there must still be enough room for
sufficient air circulation around pieces for even firing results.
Loading for glaze firing
Glaze is finely ground glass suspended in a liquid. Two glazed pieces, if allowed to touch each
other will adhere to one another when the glazes melt and re-solidify. Glaze will also adhere to
the kiln or kiln shelf. Therefore stilts are used when firing most glazed pieces. Stilts are small
ceramic or pointed metal supports; a wide variety is available (see the kiln accessories section,
page 2-1). In some cases a piece may be dry footed (the base left unglazed). Be sure that the glaze
is not applied too heavily, or it may “run” and stick to the shelf or the bottom of the kiln.
Remember to prepare the kiln with kiln wash, as described earlier, especially when firing glaze to
prevent any glaze from permanently adhering to the kiln bottom or shelves.
Glazed pieces should not be placed closer than ½” to one another since glaze bubbles before it
smoothes to its final surface. Bubbles and fumes from this process will contaminate adjacent
pieces if spacing is not at least ½.” We do not recommend that glazed pieces and bisque be fired
in the same load, since they are normally fired at different temperatures and since this could cause
discoloration. Bisque is normally fired one cone hotter than the same piece when glazed fired.
Do not stack or nest glazed pieces. Do not fire glazed pieces requiring lids with the lids in place
as they will stick together permanently.
Loading Overglaze, China Paint, Lusters, and Gold
Loading for overglaze pieces is the same as for your glazed ware, except that lusters should be
spaced at least 1” apart to avoid cross contamination.
Loading stoneware and porcelain
It is necessary to fire stoneware and porcelain at a much higher temperature than that used for low
fire ware or glaze. At this heat the ware becomes much softer than ceramic bisque. For this reason
it may stick to other pieces and so should not be stacked or nested. It will also tend to distort in
shape unless the maximum temperature is accurately controlled and the piece is properly
supported. Hollow greenware pillars made of the same material as the ware are often used for
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