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On the other side is a cone that is one number hotter than the firing cone, It is called the
GUARD CONE. If it bends at all, you know that the kiln has fired beyond the
preselected point.
The plaque of three cones should be placed on a shelf close to the level of the KILN-
SITTER tube. However, because a shelf supported by stilts is not completely stable,
the height of the shelf should be one inch above or one inch below the tube. This will
prevent a possible jamming of the normal KILN-SITTER shut-off function should the
shelf expand or tilt in the direction of the tube.
After test firing, during normal operations, you may wish to place a plaque on EACH
shelf level, since temperatures vary at different levels within a kiln. When setting your
kiln shelves, follow the kiln manufacturer's instructions. The spacing between shelves
will depend upon the objects you wish to fire. This spacing, as well as the size and
weight of your ware, has an affect on heat distribution.
After firing is completed, you will see some differences in the appearance of the test
plaques. If for example your firing was made with two or more shelves, the lower shelf
will usually show less bending of the cones than the plaque located on a shelf near the
top of the kiln. This range of heat treatment normally will be within the range
recommended for your materials.
The shelf locations, and amount of material placed on each shelf, and the switching
sequence, will have some affect upon the heat distribution in your kiln. But as long as
each plaque of cones show cone values within the range recommended for your
material, you can be sure it is receiving proper heat treatment.
Now fire the kiln in the manner recommended by the kiln manufacturer. Use the proper
switch sequence and follow venting procedures for necessary air circulation.
If witness cones, after the first test fire, appear similar to those illustrated in Figure 14,
you will know that the KILN-SITTER is in proper adjustment. But make a second test
firing exactly as you did before. This will serve as a double check and indicate the
consistency of firing performance.
If the witness FIRING cone is UNBENT, then test fire a second time using a hotter cone
on the KILN-SITTER (one number higher.)
If a second test fire, as recommended above, does not cause proper maturing of the
witness cones, as illustrated in Figure 14, then it is recommended that you recheck all
adjustments, as described in that section and repeat the two test fires.
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