Operating instructions
Hold (HOLd)
Cone-Fire Hold heat-soaks the ware at thecone temper
-
ature at the end of the firing. Without Hold, the kiln shuts
off after it reaches the cone temperature. Hold maintains
the cone temperature for theperiod you specify.Hold helps
even out the temperature throughout the kiln. It also helps
the heat to penetratecompletely into the clay. (Rapid firing
is like cooking: the turkey
will be done on the outside
but not on the inside.) Hold
helps glaze absorb china
paint. It may heal glaze de
-
fects such as bubbles. A little
hold time can yield dramatic
results.
CAUTION: Too much
hold time can overfire
your ware and burn out
colors.
One way to add Hold
time without over-firing is to fire to one cone cooler than
needed. Then addenough hold time to bend the next hotter
cone. Hold time needed to bend the next cone will vary. As
a rule of thumb, 45 - 60 minutes of hold = one cone of heat
work.
Example: to fire to cone 05, program Cone-Fire for 06
and add 45-60 minutes of hold time.
Watch the pyrometric witness cones through the peep-
hole. Press when the correct witness conebends, not-
ing how much Hold time was needed. Program that much
Hold time the next time you fire the same type of ware
loaded to the same capacity.
Note: During Hold, the display temperature will al
-
ternate with time left in Hold. To figure hold time for
the next firing, subtract time left in Hold from the total
Hold time entered.
When Hold is set to 99.99 hours, the Sentry will remain
at that temperature indefinitely, until you press .
Slow Cooling (COOL)
Slow cooling enhances the quality of some ceramic
glazesand may heal glaze bubbles. Slowcoolingencourages
crystal develoment, deeper gloss, and sometimes startling
color shifts. Iron red glazes seem to respond well to slow
cooling. For these reasons we have added a Slow Cooling
feature to Cone-Fire.
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Slow Cooling begins after the cone firing (and Hold, if
any) and ends at 392°F/200°C.
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When appears in Cone-Fire programming, en
-
ter a cooling rate between 1°F/C to 180°F / 82°C per
hour. A good starting point is a rate of 90°F / 50°C per
hour.
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Enter a rate of 0 to turn Slow Cooling off.
Note: Slow Cooling can extend the firing time by
many hours. For instance, if the cone shutoff tempera
-
ture is 1945°F / 1063°C, and the cooling rate is 100°F /
55°C, the kiln will take 15 ½ hours to reach 392°F /
200°C.
When the Kiln Shuts Off Too Soon
If the kiln shuts off before the pyrometric witness cone
bends, you can turn the kiln back on and keep firing. Simply
program the next hotter cone in Cone-Fire. Then from
, press . The kiln will begin firing, taking up
where it left off.
Note: Look at thewitness conesthrough a peepholeto
know if the kiln shuts off too soon.
If the kiln shuts off within 100°F/55°C of maturity, and
the temperature drops 50°F/28°C or more after the kiln
shuts off, do not depend on the witness cones. Once they
cool 50°F/28°C after they have been heated to within
100°F/55°C of maturity, they will not bend properly. This is
because they form a hard shell.
Wrong Thermocouple Type
If a Type-K thermocouple is installed on your kiln, but
your controller is set for Type-S, the kiln will continually
underfire by a wide margin. See page 22 to check the ther-
mocouple type.
For Kilns with AOP Outlet
The AOP(auxiliary output)is a special-order receptacle
mounted in the kiln switch box. The Sentry controls power
to the AOP receptacle. The AOP is usually used to power a
kiln vent.
The Fan option, which is accessed through the
key, determines when an AOP-powered kiln vent will oper-
ate during Cone-Fire.
Beforethe Fan optionwill appearon theOptions list,(1)
you must enter a Cone-Fire program in active memory and
(2) you must select VFAN in the AOP1 or AOP2 option.
(See page 22 for instructions on selecting VFAN.)
From , press repeatedly until
appears.
Press . Use the and keys to select one of
these settings:
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The vent is on during Pre-Heat, the cone firing,
and Slow Cooling. It turns off at 212°F/100°C.
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The vent is on during Pre-Heat and the cone fir
-
ing. It is off during Slow Cooling.
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The vent is off all the time.
Afterselectingone ofthe above,press . Press
to return to .
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Do not leave the
kiln unattended,
especially near
the expected
shut-off time. Be
there to make
sure the kiln
turns off.