Table of Contents
©1982 -1994 by Warner Instruments Grand Haven, Michigan 49417 USA
®KilnTronics is a registered trademark of the American Art Clay Company
Third Edition
September 22, 1994
™FireRight is a tradename of Warner Instruments.
This document formerly provided as Handbook Number 451004
Our products are guaranteed to be free of defects in materials and workmanship for a period of
Please return your WARRANTY REGISTRATION CARD immediately upon receiving your
Your rights under this warranty consist solely of requiring us to repair or, in our sole discretion,
The foregoing constitutes the sole and exclusive remedy of the purchaser, and the exclusive
Warner Instruments assumes no risk or liability for results of the use of its products. The giving
Installation is easy. In most cases, everything is fully assembled and
ready to use. The power line cable and kiln's power cable will have to be hard-wired
to the power contactor inside of your new power controller. Otherwise, everything
is pre-wired, so you can't go wrong.
In the beginning, 07 control systems were shipped either with a "field kit"
box mounted on the side of the kiln, which contained a power contactor and fuse ...
or with the contactor built right in as an integral part of the kiln's switch box.
Due to the limited space inside the switch box on most kilns, and the possibility
of rather high ambient temperatures, the "integral" set up is no longer
recommended. Field kit boxes (called "power controllers" herein) may
still be mounted on the outside jacket of the kiln, near its bottom, if desired ...
but a better way is now recommended. We're now suggesting the power controller be
mounted on the wall, just above the 50-amp electrical receptacle which you've
provided for the kiln (or just below its breaker box, if your kiln draws more
than 50-amps or must otherwise be direct-wired).
This set up assures that the components of the control system will not be subjected
to temperatures higher than room temperature, and also permits you to use the control
system with any standard kiln (no modification or alteration of the kiln is required).
The following instructions apply to these "factory pre-wired" systems. If
you have purchased a controller only and intend to connect it to your own power
controls, refer to the wiring diagrams in the appendix for further hook-up details.
MOUNTING THE POWER CONTROLLER
MOUNTING THE TEMPERATURE SENSOR
CHOOSING A LOCATION FOR THE SOAK/SHUT-OFF CONTROLLER
HOOKING THINGS UP
Never connect the sensor cable to the controller if the
POWER CONTROLLERS AND KILN SWITCH BOXES CONTAIN VOLTAGES WHICH
NEVER OPERATE THIS EQUIPMENT WITH THE COVERS REMOVED.
Refer to the front panel of your Soak/Shut-OFF Controller as you
read through the following explanation of what each front panel feature is and
does. Don't be afraid to push the buttons and turn the knob. You won't break
anything.
ON/OFF SWITCH
This switch turns the controller on and off, and thereby serves as an on/off
switch for the kiln. Push this switch in to turn the control system on; push
it again to release it, turning the system off.
Important Point No 1: It's important for you to know that the
controller has a built-in safety feature which assures that it will always
start up in the "latched off" condition. This feature is activated
whenever power is first applied to the controller ... which may be when you
turn it on, or when power is restored following momentary power failures (caused
by lightening strikes, or backing into the power pole at the end of the driveway).
It assures an orderly, operator-directed start-up. It also assures that the
equipment will not automatically restart itself, re-firing a previously completed,
or partially fired, load.
Important Point No 2: It's also important for you to know that the
controller never shuts itself off; it latches its output off, but otherwise remains
fully operational. There will be more on this below, but for now just remember
that the control system is really turned off only when you physically turn it off
with this switch.
THE TEMP ADJ CONTROL
In a conventional firing, you might increase the kiln's temperature to some
maximum value, then shut the kiln off and allow it to cool at its own rate. The
"maximum value" will hereinafter be referred to as the Limit Setting
when using this controller.
To set the limit temperature, simply move the TEMP
ADJUST knob until its pointer rests exactly at the
desired temperature setting.
Important Point No 5: The TEMP ADJUST knob is always enabled,
so once you set it, be careful not to accidentally bump it, thereby inadvertently
changing its setting. Make it a practice to verify the limit setting as a last
step, whenever you do anything else at the control panel.
If, for whatever reason, your kiln is unable to attain
temperatures as high as your limit setting (e.g., low-fire
kiln, low voltage at the kiln, defective heaters or switches,
etc.) the controller will not be able to shut it off at the
limit, and an over-firing may result.
You should not leave your kiln unattended beyond the planned firing time. If you plan
to do so, you should equip your control system with either an optional shut-off timer,
or a program time clock, to provide a back-up safety device which will assure that
the kiln is shut off within a reasonable period of time in the event that something
goes wrong.
SOAK/RESET
This switch selects the operating mode of the controller. When pressed in
("SOAK" position), the controller operates just like any common temperature
controller or thermostat, regulating the kiln's heat as necessary to keep the
temperature at the Limit setting. When left in the out ("SHUT-OFF")
position, the controller will shut the kiln off when its temperature reaches the
limit setting, permitting the kiln to cool at its own rate.
Push this switch in to select the SOAK mode; push it again to release it,
which selects the SHUT-OFF mode.
PREFIRING CHECK-OUT PROCEDURE
Now let's check out the whole control system.
Other countries may have similar requirements ... please check with your local
FIRING INSTRUCTIONS
GENERAL INFORMATION
Firing practices and techniques vary widely. There are probably as many
different opinions as there are books on this subject ... and as you read more
and more, you will find that conflicting information is commonplace. But there's
a message in that, right? ... firing might not be so complex or critical as many
writers and teachers suggest, and the limits of error are probably fairly wide. So
rejoice; you can probably master it!
But while we're rejoicing ... let us not loose sight of the fact that firing is
also "an art", and as your experience and skill increase, and as you
attempt to create particular effects or duplicate previous results, you will become
increasingly more concerned with its subtleties. Eventually, you'll forget about
the basics and details, and set up each firing with no more forethought or difficulty
than normally applied to the humming of a favorite tune. Then, when it comes to firing,
you'll also insist on "the Gospel According to You" ... and why not?
... it works for you!
If you're already an expert, you might read the following just for entertainment ...
to see what we say wrong (and to read some things that you forgot about a long time
ago). If you're not an expert, welcome to our non-exclusive club. Let's get to
it!
The stages in a bisque (or "biscuit") firing are generally summarized
as follows:
Points of special interest in the firing process focus around moisture removal
and the processes known as "silica inversions". The rate of temperature
increase through the 0 - 300°F (0 - 150°C) range must be slow enough
to permit steam to escape through the clay without building up bubbles which
will eventually burst and ruin the piece. At about 440°F (225°C), and
through the range 1020 - 1070°F (550 - 575°C), the silica inversions
cause a sudden expansion (if heating) or contraction(if cooling) of the body.
If heated or cooled too rapidly through these inversions, the piece might be
damaged or deformed by stresses which develop if its temperature is not perfectly
uniform throughout its mass ... causing some areas to suddenly expand or contract
before others.
Commercial green-ware and other typically thin pieces will usually tolerate
firing rates up to 270°F (150°C) per hour. Thicker pieces will obviously
require slower firing, as will pieces with thick sections, such as pots with heavy
bases ... perhaps as slow as 100°F (55°C) per hour.
PYROMETRIC CONES
Firing instructions provided with materials, or in texts and
magazine articles, frequently refer to cone numbers rather than temperatures,
because the heat treating process involves both time and temperature.
Pyrometric cones are special formulations which are designed to mature at
different extremes of applied heat, are therefore useful in gauging the
progress of a firing. The 'time vs temperature' relationship is reflected
in the tables furnished in standard cone
charts.
As you can see, a "cone 6" firing can result from a variety of
schedules ...
When firing with the controller, you must establish the Limit setting on the
basis of the terminal firing rate (i.e., the rate of temperature change
at the end of the firing), using the data presented in this table as a guide.
This matter of rate vs limit setting naturally applies to the final few hundred
degrees of the firing, and you must also consider the nature of the load ...
is the rate slow enough to assure a reasonable degree of temperature uniformity
throughout just prior to shut-off? On the other hand, if you're firing to a high
temperature ... say, over 2100°F ... you might well expect that your kiln
will not have enough heating capacity to maintain a 270°F/Hr rate,
so the "final approach" will occur at some slower, kiln dependent,
rate. Experience will help you decide how much to "fudge" on the limit
setting to compensate for this "kiln lag".
OVERTIME OR OVER-TEMPERATURE - OVER-FIRED WARE!
This is a simple, but often overlooked point ... its important that
you remember it. You can see from the Cone Charts that firing is a matter of (1)
temperature and (2) time. Too much, or not enough, of either ... and the results
will be poor; perhaps a complete loss. Keep this in the back of your mind: if
you come up with an over-fired load, it can just as well be the result of too much
time, as too much temperature.
Suppose that you're firing to a fairly high temperature ... near the limit of
your kiln's capability. Its getting late, and everything's gone fine up to this
point, so you trustingly retire thinking that the kiln will shut off in an hour
or so anyway. But then the maintenance people at the power plant shut down one
of the generators for a quick oil change during the 'off peak' hours. Your line
voltage just dropped 5% ... and so did your kiln's heating capacity.
Eventually the sun comes up. After breakfast you go down to unload the kiln ...
ouch! Its still a bit too warm. That's odd, looks like it switched off ok. Humm ...
Oh well, let's open it up anyway ...
You'll probably never find out why this happened ... and for a long time your
confidence in the control system will be shaken. It happened, of course, because
the volt-loss during the night was just enough to make your kiln "stall
out" just below the Limit setting. So it just sat there and cooked all
night long, until the power come back up; then it finally shut off. Even though
the temperature never got higher than the Limit setting, the ware was fired far
too long at that high temperature, and melted down.
There are other ways that this can happen and, as you've probably guessed, it
does happen. This is one of the hazards firing with electric kilns. The main point is this:
IF YOU CAN'T BE ON HAND TO ASSURE THAT THE KILN SHUTS-OFF ON SCHEDULE, ADD A
SHUT-OFF TIMER OR PROGRAM TIME CLOCK TO YOUR CONTROL SYSTEM AS A BACK-UP DEVICE
That's the main point. But remember also that if a load has fired properly according
to your schedule, but appears to be a little overfired, shorten the firing schedule
next time. This can be accomplished simply by reducing the Limit setting somewhat.
The reverse would apply to an underfiring, of course, maybe you rushed it too much.
BASIC (BISCUIT) FIRINGS - Step by Step
CRYSTALLINE GLAZE
Appendix
CONE CHARTS
WIRING DIAGRAMS
DN470327: for 110-120vac Systems, original relay output configuration (28Kb)
one (1) year from the date of purchase.
control system. We must otherwise use our factory shipping date as the effective date of purchase,
unless you are able to provide some other proof of purchase upon application for warranty service.
to replace, free of charge, F.O.B. our factory, any defective product received in good condition at
the factory within one (1) year from the date of purchase, and determined by us to be defective as
claimed. Any defect appearing more than one (1) year from the date of purchase will be deemed to
be due to ordinary wear and tear. Our products are identified by serial numbers, and cannot qualify
for warranty service if their serial number has been altered or obliterated, or is missing entirely.
liability of Warner Instruments, AND IS IN LIEU OF ANY AND ALL OTHER WARRANTIES;
EXPRESS, IMPLIED OR STATUTORY AS TO MERCHANTABILITY, FITNESS FOR PURPOSE
SOLD, DESCRIPTION, QUALITY, PRODUCTIVENESS, OR ANY OTHER MATTER.
of, or failure to give, any advice or recommendations, shall not constitute any warranty by, or
impose any liability upon Warner Instruments. IN NO EVENT SHALL WARNER INSTRUMENTS
BE LIABLE FOR SPECIAL OR CONSEQUENTIAL DAMAGES, OR FOR DELAY IN
PERFORMANCE OF THIS WARRANTY.
and your wall receptacle must match. Standard replacement cords and wall
receptacles are normally available from your local kiln dealer, if required.
thermocouple element is not securely fastened to the kiln.
If the sensor should happen to fall out of the kiln, an
over-firing could easily result!
RE HIGH ENOUGH TO PRODUCE LETHAL ELECTRICAL SHOCKS.
REFER SERVICING TO QUALIFIED PERSONNEL.
EXPLANATION OF THE CONTROLS
WARNING
.
prior to shipping controls for service. You should complete forms B13 and E15,
which identify the equipment as your property and certify that the required
service is not available in Canada. Our return shipment to you will otherwise
be delayed in Canadian customs, and you might be reassessed duty on the value of
equipment in question.
postal or customs authorities prior to shipping your property out of your country.
to 2232°F (1222°C) in 8.27 hours,
to 2291°F (1255°C) in 4.24 hours,
... etc.
During the Firing ..
DN470328: for 208-240vac Systems, original relay output configuration (29Kb)
DN470326: for 110-120vac Systems, dc pulse output (modified controls) (30Kb)
DN470325: for 208-240vac Systems, dc pulse output (modified controls) (31Kb)
1320 Fulton Street Box 604
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Phone:(616) 842-7658
FAX:(616) 482-1471
e-mail: info@fireright.com
© 1977 -1998 Warner Instruments
Page Last Revised on March 29, 1998
