Firing Charts:
It is a valuable practice to keep a written record of each firing, noting the settings (even the
degree of deformation of witness cones and their locations). This firing chart allows you to repeat
good results and successful firings and avoid repeating less than satisfactory firing results; see
firing chart on page 12-1.
After Firing:
After every firing, check the limit timer; there should be approximately 10 to 15 minutes left at
time of Kiln Sitter
® shut off. You should correct the timer on the next firing if there is more than
30 minutes left on the timer so that the timer works as an effective backup on the firing. Should
the Kiln Sitter
® fail and you forget, this could be a very important safety factor in saving the kiln
and your work from destruction.
Also check the Kiln Sitter. Observe the pilot lights (they should be off) and the position of the
Kiln Sitter weight: make sure it has fallen and has actually turned the kiln off. Correct any
maladjustment problems early before damage is done to the kiln and ware. Always turn the
thumbwheel to “▲” and the limit timer to “off” after each firing even if the Kiln Sitter appears to
have functioned correctly. The Kiln Sitter is used for added safety and for controlled firing; it is
not fail proof and cannot be guaranteed to turn off every time.
FIRING FOR BEST RESULTS
The following suggestions are general good practices to be observed for the most satisfactory results.
● Slow heating and cooling rates add quality and minimize crazing, cracking and breakage problems. Let
the kiln cool at least over night then crack the lid and let pieces cool until they may be handled with bare
hands. If this suggestion is not observed, you will put permanent stress in your pieces making them
weaker and more subject to breaking and crazing.
● Watch firings closely to protect from overfiring. Firing too hot will damage fine detail and fade colors.
● Keep the inside of your kiln free from dust and chips, which cause imperfections in pieces. A vacuum
cleaner is useful in this regard.
● Always fire only bone dry ware.
● A cone plaque containing three cones (guide cone, firing cone, and guard cone- See temperature
indication) is often useful ad a monitoring and warning device. Always place witness cones uniformly at
an 8 degree angle from vertical.
Recognizing Firing Faults
BLOTCHY BISQUE is likely to be caused by stacking too compactly, not allowing for sufficient air
circulation during firing which results in uneven firing. Try loading more loosely and re-firing.
WARPED BISQUE may be due to one of the following causes:
Overfiring.
Placing ware too close to the elements.
Stressing a delicate area by improper support.
Removing ware incorrectly from the mold.
FAILURE OF GLAZE OR UNDERGLAZE TO ADHERE TO THE WARE (crawling glaze) can be
attributed to one of the following causes:
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