Sentry Sentry 2.0 Betriebsanleitung PDF herunterladen (Seite 12)

High Fire Cones 1 -10

This is the firing range for porcelain and stoneware.

These bodies fire nearly to vitrification and can shrink up to

16%. Water, carbon and sulfur burn out during the early

stages and must be vented. The amount of oxygen in the

kiln affects the colorof the firedclay. Thehigh fire schedule

below slows down during the last 210°F/100°C to produce

better density in the ware.

Typical porcelain clays are formulated from kaolin, feld

spars, silica and ball clays. Weight loss is 10 - 12% and

shrinkage is as high as 20%. If over-fired, porcelain may

warp or blister. The Cone-fire Hold option usually en

hances porcelain.

High Fire Cones 1 - 10 Standard Schedule

Segment Rate Per Hour Time in Segment

1 324°F/180°C 2 hours, 30 minutes

2 153°F/85°C 35 minutes

3 162°F/90°C 4 hours, 35 minutes

4 108°F/60°C 2 hours

Firing time is 9 hours, 30 minutes to 11 hours, depending on the cone and

speed.

Cone-Fire Features

Speed (SPd)

The Cone-Fire schedules shown on pages 11 - 12 are

standard. When you select Medium speed in a Cone-Fire

program, the kiln uses these standard firing schedules.

When you select Fast (1), the standard schedule fires 20%

faster. On Slow (3), it fires 20% slower.

You can also alter the firing speed even more under

Speed (SPd) in Options. You can increase or decrease the

firing time of a standard schedule by up to 40%. For in

stance, if you are on a tight deadline, you can

reducea7 hour fastcone firing to5 ½hours.

Pre-Heat (PRHT)

Moist greenware can explode during fir

ing. This happens when the moisture in the

clay turns to steam rapidly and cannot escape

fast enough. The Sentry Pre-Heat feature

dries the ware at low temperature before the

moisture can turn to steam.

Pre-Heat is sometimes 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.

Note: During Pre-Heat, vent the lid or use the op

tional Orton Vent Master. Otherwise the firebricks will

absorb moisture, leading to rust behind the steel case.

Moisture in the firebricks can also slow the firing to a

crawl.

CAUTION: Venting the lid during Pre-Heat is so im

portantthatsome ceramists usethe extended vent posi

tion or even leave the lid open. If you do this, you must

benearyour kiln at the endof Pre-Heat to lower thelid.

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

specify. Pre-Heat works in Cone-Fire only. After Pre-Heat

is finished, the kiln will automatically begin firing to the

cone you have selected.

Note: Above an altitude of 6,000 feet, water boils at a

lower temperature. This may cause moisture in the

ware to turn to steam even during Pre-Heat.

Mirror Test

This test will help you de

termine how much

Pre-Heat to use.

Occasionally during

Pre-Heat, hold a mirror

near the top peephole. (Be

careful to avoid burns.) The

mirror must be at room tem-

perature, not hot, so hold it

near the peephole for only

several seconds.

If the mirror fogs, mois-

ture is stillescaping fromthe

ware. When the mirror no longer fogs, you can exit

Pre-Heat and begin the firing.

To interrupt Pre-Heat and begin firing to the cone in

Cone-Fire, press (Skip Segment). , alternating with

, will appear.Press . Segment1 of the firingwill

now begin. (See Cone-Fire firing schedules,

pages 11 - 12.)

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 mois

ture. (AOP Fan users: see the Fan option,

page 21.)

How to Use Pre-Heat When Kiln is Above

200°F/93°C at Beginning of Firing

If you begin firing with Pre-Heat in a kiln

that is already hotter than Pre-Heat tempera

ture, the kiln will skip Pre-Heat and begin fir

ing to the cone. There are two ways to use

Pre-Heat in this situation:

Wait until the kiln cools below 200°F before starting the

firing. This is the preferred method.

Load the kiln and start the firing, but include enough

time in Delay for the kiln to cool below 200°F before

Pre-Heat begins.

12 Cone-Fire / Ramp-Hold

Vent the kiln until moisture no lon-

ger fogs a mirror.

If Cone-Fire Fast

speed is too slow,

use the SPd

Option to in

crease firing

speed. (page 19)

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 39 40

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