David Woof on mon 24 jul 06
Annapoorna, an interesting experiment, take several pyrometers and fire
with all in same area of kiln and then in various locations. Pyrometers
are not to be trusted, and same pyrometer will vary in "accuracy" between
fireings. Another variable that pyrometers can't anticipate is varying
kiln load density and thickness of pieces as a pyrometer measures only the
tempreture of kiln atmosphere.( Which is why that ascending/decending
erratic reading drives novice wood firers frantic.) Clay requires time
to absorb heat and transform to mature ceramic. the pyrometer reading is not
representing the heat work being accomplished in the clay and glazes.
It is educational to review charts that compare temp., fireing times and
rate of rise, with cone responses. do your own charting each fireing with
cones, pyrometer, and clock.
Place the cones in several visible locations in kiln. add one cone higher
than your target temp, and several ramp up witness cones like 4,6,8,9 if 10
is your target. these will allow you to note the rate of rise and help you
anticipate visual checking intervals when you are nearing your target time.
You may have to compromise a shut down time because of maturity variations
within the load which will be accurately represented by the cones. Using
Glazes with at least a two cone range will insure good results as you learn
the kiln and equipment.
Creative stacking of a difficult kiln to get even fireings could be another
subject for discussion (again, it's been awhile).
Best,
David
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David Woof Studio
Clarkdale, Arizona
Ph. 928-821-3747 Fax. 866-881-3461
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peering over the edge, reverently taking an irreverent look at everything.
annapoorna sitaram on tue 25 jul 06
hello
thank you David Woof for your suggestion.
i generally fire very slowly and when i reach the desired temp i hold for a
while .
annapoorna sitaram
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