Hold; Pre-Heating The Ware - Paragon DTC 1000 Operation & Maintenance Instructions Manual

Medium (2)
Use Medium for larger slip-cast pieces or more tightly
loaded kilns.
Cone-Fire Medium Firing Schedule
Segment in
"Present Actual
Status" Segment Rate of Firing Per Hour
4 — Pre-Heat (if any)
5 1 110° F. per hour until 250° F.
6 2 400° F. per hour until the last 250° F.
7 3 120° F. per hour during the last 250° F.
Slow (3)
Use Slow for hand-thrown or heavily-cast pieces, stone-
ware and porcelain.
Cone-Fire Slow Firing Profile
Segment in
"Present Actual
Status" Segment Rate of Firing Per Hour
2 — Pre-Heat (if any)
3 1 80°F per hour to 250°F
4 2 250°F per hour until temperature
reaches 950°F
5 3 110°F per hour until temperature
reaches 1100°F
6 4 225°F per hour until the last 200°F
7 5 90°F per hour during the last
200°F of firing
8 6 150°F per hour, cooling down to
1000°F

Hold

Cone-Fire "Hold" heat-soaks the ware at the end of the fir-
ing. Without Hold time, the kiln shuts off after it reaches the
cone temperature. With Hold time, the kiln maintains the cone
temperature for the period you specify. Hold time helps even
out the temperature throughout the kiln. It also helps the heat
to penetrate completely into the clay. Rapid firing is like cook-
ing: the turkey will be done on the outside but not on the in-
side. Hold helps glaze absorb china paint. It helps to heal glaze
defects 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 add enough hold time to
bend the next hotter cone. Hold time needed will vary. As a rule
of thumb, one hour of hold = one cone of heat work.
Example: to fire to cone 05
and add 30 minutes of hold time.
, program Cone-Fire for 05
1
2
Watch the pyrometric shelf cones through the peephole.
Press STOP when the correct shelf cone bends, noting 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. You can hold for up to 99 hours and 99 minutes.
You will learn by experimenting with ceramics. Hold is one
more tool to experiment with.

Pre-Heating the Ware

Moist greenware can explode during firing. This happens
when the moisture in the clay turns to steam rapidly and can-
not easily escape. The DTC 1000 "Pre-Heat" feature dries the
ware at low temperature before the moisture can turn to
steam.
Pre-Heat is necessary when firing thick greenware, such as
stoneware. It may also be necessary in humid weather, which
inhibits drying. If possible, however, avoid using Pre-Heat to
dry greenware. If the greenware feels damp or cool when you
touch it to your cheek, dry it longer before firing. Use a
dehumidifier in humid weather. Drying greenware in the kiln
tends to rust the kiln.
TIP:
During Pre-Heat, vent the lid. Otherwise the fire-
bricks will absorb moisture, leading to rust behind the
stainless steel case. Moisture in the firebrick will also
slow the kiln to a crawl when firing begins.
Venting the lid during Pre-Heat is so important that some
ceramists use the extended vent position or even leave the
lid open. If you do this, you must be near your kiln at the
end of Pre-Heat to lower the lid.
Pre-Heat raises the temperature 60°F/33°C per hour to
200°F/93°C. Then it holds at 200°F/93°C for the time you spec-
ify. Pre-Heat works in Cone-Fire only. After Pre-Heat is fin-
ished, the kiln will automatically begin firing to the cone you
have selected. Pre-Heat zeroes out after each firing.
CAUTION:
At high altitude, water boils at a lower
temperature. This may cause the ware to dry too rapidly
even during Pre-Heat.
After entering cone number, speed, etc., in the Cone-Fire
program, activate Pre-Heat as follows. Then begin firing.
1 Press
ENTER .
2 Press
0 repeatedly until
3 Press ENTER .
Hld
.
00.00
4 Enter Pre-Heat hold time in hours and minutes (i.e. 1
hour, 30 minutes = 01.30).
5 Press ENTER .
CPL
appears.
PrHt
will appear, alternating with
will appear, then .
IdLE
7