When Hold is set to 99.59 hours, the Sentry Xpress will
remain at that temperature indefinitely, until the
Start/Stop
key is pressed.
Slow Cooling [COOL]
Slow cooling, also called down firing, enhances the qual-
ity of some ceramic glazes and may heal glaze bubbles. Slow
cooling encourages crystal develoment, deeper gloss, and
sometimes startling color shifts. Iron red glazes seem to re-
spond well to slow cooling.
I
The
[COOL]
prompt does not appear in the display dur-
ing programming until you activate the Slow Cooling
Option. See page 17.
I
The Sentry’s Slow Cooling begins after the cone firing
and ends at 800°F / 426°C.
I
When
[COOL]
appears in Cone-Fire programming, en-
ter a cooling rate between 1°F - 180°F / 1°C - 82°C per
hour. A good starting point is a rate of 90°F / 50°C.
I
Enter a rate of 0 to turn Slow Cooling off.
Pointer:
If the kiln seems to take forever to shut
off, press the
Down Arrow
for Present Status.
Check the Slow Cooling rate. The firing time can
extend for many hours if the cooling rate is too
slow. This also adds to element wear.
How to Customize Cone-Fire
You can customize a Cone-Fire program using
Ramp-Hold. (See the next section.) On pages 30-31, tables
show the segments used to program each cone number in
Cone-Fire. For instance, a cone 016 firing at medium speed
[STD]
uses these two segments:
Rate
Temp.
Segment
°F/°C
°F/°C
Hold
1
396 / 220
1314 / 712
00.00
2
108 / 60
1422 / 772
00.00
Suppose your 016 witness cone, at a medium speed fir-
ing, only barely started to bend. To fire 25° hotter, raise the
target temperature of segment 2 by 25°:
1422 + 25 = 1447
This is the program you would enter in Ramp-Hold:
Rate
Temp.
Segment
°F/°C
°F/°C
Hold
1
396 / 220
1314 / 712
00.00
2
108 / 60
1447 / 786
00.00
You could also easily add a slow cooling segment:
Rate
Temp.
Segment
°F/°C
°F/°C
Hold
1
396 / 220
1314 / 712
00.00
2
108 / 60
1447 / 786
00.00
3
100 / 55
1000 / 537
00.00
Question
My kiln is taking too long to fire: 9 ½
hours to cone 6. I want the kiln to fire in 4 hours.
Answer
9 ½ hours is the firing time programmed
into the Cone-Fire mode at fast speed. The easiest
way to go faster is to use Ramp-Hold mode, where
you can program the exact speed you want. Note,
however, that the firing speed is limited to the
kiln’s heating capacity.
For Kilns with the AOP Outlet
The AOP (auxiliary output) is an optional receptacle, or
socket, mounted on the kiln. Plug a kiln vent into the recep-
tacle, and use your controller to turn on the vent automati-
cally. You must select
[VFAN]
(Vent Fan) in the
[AOP1]
option. See page 22.
When the Kiln Shuts Off Too Soon
Ceramic Firings
If the kiln fires to completion before the pyrometric wit-
ness cone bends, you can turn the kiln back on and keep fir-
ing. Program for a hotter cone following the instructions in
the red box, page 10. The kiln will begin firing, taking up
where it left off.
Note:
By seeing the witness cones through a peep-
hole, you will 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 K-Type thermocouple is installed on your kiln, but
S-Type is selected in Options, the kiln will continually
underfire by a wide margin. (The kiln will overfire if S-Type
is installed and K-Type is selected.) See the TC option,
page 18, to check the thermocouple type selected.
Starting a Firing in a Hot Kiln
If you ever need to begin a firing when the kiln is already
hot, begin the program as you normally would. The Sentry
Xpress will automatically begin firing from the first seg-
ment that matches the current kiln temperature.
Keep the kiln lid or door closed when the kiln is not in use.
11
The Orton Vent Master can be turned on or off
throughout the firing through the controller.
