Note:
If you are using a vent fan, such as the Orton
Vent Master, leave the fan on during Pre-Heat.
The fan will help to remove moisture. (Kilns
equipped with the AOP Fan: see the Fan option,
page 21.)
How to Use Pre-Heat When Kiln is Already Above
200°F/93°C at Beginning of Firing
If you begin firing with Pre-Heat in a kiln that is already
hotter than the Pre-Heat temperature, the kiln will skip
Pre-Heat and begin firing to the cone. There are two ways
to use Pre-Heat in this situation:
I
Wait until the kiln cools below 200°F / 93°C before start-
ing the firing. This is the preferred method.
I
Load the kiln and start the firing, but include enough
time in Delay for the kiln to cool below 200°F / 93°C be-
fore Pre-Heat begins.
Temperature Hold [HOLD]
Cone-Fire Hold heat-soaks the ware at the cone temper-
ature. Without Hold, the kiln shuts off after it reaches the
cone temperature. Hold maintains the cone temperature
for the period you specify. Hold helps even out the temper-
ature throughout the kiln. It also helps the heat to penetrate
completely into the clay. (Rapid firing is like cooking: the
turkey will be done on the outside but not always on the in-
side.) Hold helps glaze absorb china paint for saturated
colors. It may heal glaze defects such as bubbles. A little
hold time can yield dramatic results.
Pointer:
Too much hold time can overfire your
ware and burn out colors. Be sure to experiment
with hold before firing a full load of ware with hold.
One way to add Hold time without over-firing is to fire to
one cone cooler than needed. Then add enough hold time
to bend the next hotter cone. As a rule of thumb, roughly 20
minutes of hold = one cone of heat work.
Example: to fire to cone 05, program Cone-Fire for 06
and add about 20 minutes of hold time.
Watch the pyrometric witness cones through a peephole.
Press
STOP
when the correct witness cone bends, noting
how much Hold time was needed. Program that much Hold
time the next time you fire the same type of ware. (During
Hold, the temperature will alternate with time left in Hold.
Subtract that amount from the total Hold time entered.)
When Hold is set to 99.59 hours or higher, the Sentry will
remain at that temperature indefinitely, until you press
STOP
.
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 Slow Cooling with
the Options key. See page 21.
I
The Sentry’s Slow Cooling begins after the cone firing
and ends at 1500°F / 815°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
5
for Present Status. Check the Slow
Cooling rate. The firing time can extend for many
hours if the cooling rate is too slow.
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
[IDLE]
, press
START
. The kiln will begin firing, taking up
where it left off.
Note:
Look at the witness cones through a peep-
hole to 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 underfire. See
the TC option, page 21, to check the thermocouple type.
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. That is done through the Fan option.
But before
[FAN]
will appear in the Options 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]
.)
1
From
[IDLE]
, press
OPTIONS
repeatedly until
[FAN]
appears.
2
Press
ENTER
. Use the
1
and
2
keys to select one of
these settings:
I
[ON]
The vent is on during Pre-Heat, the cone firing,
and Slow Cooling. It turns off at 212°F/100°C.
I
[OPT]
The vent is on during Pre-Heat and the cone fir-
ing. It is off during Slow Cooling.
I
[OFF]
The vent is off all the time.
3
After selecting one of the above, press
ENTER
.
Press
STOP
to return to
[IDLE]
.
Keep the kiln lid or door closed when the kiln is not in use.
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