703117, 703118 PMC Kilns.indd

Rio Grande PMC® Kilns #703-117 & #703-118
Instruction Handbook
Table of Contents
Safety Precautions
Setting Up the Kiln
Basic Operation
Important Guidelines
Controller Programming
General Firing Instructions
Ramp-Hold Mode
Alarm Feature
Error Messages
Display Messages
Combining PMC® with Other Materials
Lost-Wax Burnout
Firing Mistakes
Kiln Maintenance
Bead Door & Mandrel Holder (model #703-118) 24
When your Rio PMC® kiln is delivered, note any external
evidence of loss or damage on the freight way bill or express
receipt and have it signed by the carrier’s agent. Failure to
adequately describe such external evidence of loss or
damage may result in the carrier’s refusal to honor your
damage claim. The form required to file such a claim will
be supplied by the carrier.
Important information about your kiln is recorded on its
electrical data plate. Please include this information when
ordering parts or calling Rio Grande with questions about
your kiln.
Concealed loss or damage means loss or damage which
does not become apparent until the merchandise has been
unpacked and inspected. Please examine your kiln carefully as you unpack it. If there is any visible damage, do not
attempt to operate it.
Should either external or concealed damage occur, make a
written request for inspection by the carrier’s agent within
15 days of the delivery date. File a claim with the carrier for
any damage that is caused by the carrier.
Save your shipping carton; it is carefully designed to
provide maximum protection during shipping. Repack
the kiln in the carton to take it to seminars or on vacation,
or to send it for repairs.
Please Note:
Tremendous stresses are generated within the kiln. The
ceramic fiber firing chamber actually expands and contracts
with each firing, so do not be concerned if small cracks
appear in the fiber as this is normal. These are surface cracks
that close tightly when the heated fiber expands. You may
find a small pin-hole in the center of the firing chamber. It
is from the manufacturing process and will not affect the
kiln’s performance.
Also note that paint around the door will eventually discolor
from heat. Again, this will not affect the kiln’s performance.
During firing, you will hear an intermittent, distinct clicking.
This is the sound of the relay(s) sending power to the heating elements. Do not be concerned with this sound.
Safety PrecautionS
Read Your Handbook
Read each page of this handbook carefully before operating
your kiln. The warranty does not cover damage caused by
failure to follow instructions.
Safety Rules
An electric kiln is extremely safe to operate provided you
follow these basic safety rules:
• DANGeRoUS VoLTAGe! Do not touch the heating
elements with anything.
• Disconnect the power when the kiln is not in use.
• Install your kiln at least 12" away from walls and any
potentially combustible surfaces.
• Fire only in a well-ventilated, covered and protected area.
• Never fire tempered glass inside the kiln; this type of glass
could explode.
• Never fire toxic materials, such as styrofoam (used
as a core for hollow beads), inside the kiln.
• Keep any combustible materials away from the kiln
at all times.
• Wear properly rated safety glasses when looking into the
firing chamber of a hot kiln or when cutting glass.
• Do not leave the kiln unattended while firing, especially
near the expected shut-off time.
• Do not touch the hot kiln case; keep unsupervised
children away.
• Keep the cord-set away from the hot kiln case.
• Do not open the lid or door until the kiln has cooled
and all switches are off.
• Keep food away from your work area.
• Disconnect the kiln before servicing.
The warranty on your Rio PMC® kiln does not cover damage
from over-firing, regardless of the circumstances. It is the
operator’s responsibility to make sure the kiln turns off at
the proper time.
The Ceramic Fiber
Avoid touching the firing chamber surface with sharp
or pointed objects that can damage the fiber surface.
Food or Drink Containers
Some decorative materials may be unsafe or toxic on
surfaces that will be in contact with food or drink.
When you make food or drink containers, select a glaze
or glass that has been formulated, tested and labeled as
approved for surfaces that will be in contact with food or
drink. Follow the glaze or glass manufacturer’s instructions
exactly, without any variations.
Setting uP the Kiln
area such as a garage, basement, utility or hobby room.
Please Note: Some people keep their kiln outside on a
covered patio. This is acceptable so long as the kiln is not
subjected to excessive humidity and has good ventilation.
2. Remove gasoline, paint and all other flammable materials
from the kiln room.
3. Provide a minimum of 12" of clearance between the kiln
and the nearest wall; keep the kiln away from curtains
or other combustible materials.
4. Never allow the temperature of your firing room to
exceed 100°–110°F. Measure the temperature about
three feet from the kiln. If necessary, use fans to reduce
room temperature.
5. Position the kiln on a level, fire-proof surface such as
an 18" x 18" sheet of metal or a large ceramic kiln shelf.
6. Keep unsupervised children away.
7. Keep the power supply cord away from the kiln case.
Important: Provide your kiln with a circuit that no other
appliance uses while the kiln is firing. To check the circuit,
turn off the circuit breaker (or unscrew the fuse) for the
circuit that your kiln will use. Check to see if any other
appliances shut off too. If that circuit powers appliances
that must remain on while the kiln is firing, choose a
different circuit.
Please Note: With 120volt kilns, avoid using
an extension cord if
possible. If you must
use one, never use one
smaller than 12-gauge
or longer than 20 feet.
Important: Never plug
the kiln or extension
cord into a ceiling
Voltage fluctuation can
vary firing time from as
little as half the average time to more than twice the average
time. If the voltage is too low, the kiln may never reach full
The receptacle for the kiln must have a separate safety
grounding wire. This protects you from serious electrical
shock. Changing the cord plug configuration in any way
will void your warranty.
Place the kiln on a fire-proof surface.
There is little danger of a serious burn from accidental
contact if you exercise the same caution you would use
with an electric iron.
You may want to take your kiln to seminars. The best way
to transport the kiln is to use the original packing materials.
If you no longer have the packing materials, transport
the kiln on its back (with the door facing up). Place a thin
sheet of foam cushioning between the door and the firing
chamber to prevent rubbing. Avoid subjecting the kiln to
excessive vibration during travel.
baSic oPeration
1. Place your kiln in a well-ventilated, covered and protected
Ceramic Fiber Shelf
The soft ceramic fiber
shelf, provided with the kiln,
cradles PMC® pieces. Four
ceramic feet raise the shelf
off the kiln floor. This shelf is
not suitable for enameling or
firing glass or ceramics. Do
not coat the fiber shelf with
glass separator or kiln wash.
Ceramic Fireclay Shelf
& Posts
A ceramic fireclay shelf,
available in your Rio Grande
Tools & Equipment catalog,
protects the firing chamber bottom and provides a
smooth firing surface. Use a
ceramic shelf to fire ceramics, glass and enamels. Firing
glass, enamel or ceramic glaze directly on the firing chamber
bottom will ruin the bottom. Shelves can be stacked using
Insulating Firebrick Piece
Insulating firebricks are
porous, light-weight and
can be shaped to support
delicate clay designs. Shape
the firebrick with a knife or
separator and kiln wash is that the separator is ground more
finely to leave a smooth back on glass pieces laid on the
As powders, glass separator and kiln wash have an unlimited
shelf life. Warning: Do not inhale the powder when mixing.
Caution: If glass separator or kiln wash contact a heating
element, that element will burn out during the next firing.
Never apply glass separator or kiln wash to the ceramic
fiber firing chamber.
Haik Brush
The haik brush is used to apply glass
separator to the kiln shelf in a smooth,
thin layer. The smoother the glass
separator, the smoother the underside of the glass will be.
Alumina Hydrate
Delicate PMC® shapes may need extra support during firing
to prevent warping. Place these shapes in a thin layer of
alumina hydrate inside a small clay/silica melting crucible.
Warning: Do not inhale alumina hydrate.
A stilt is a point
embedded in a ceramic base. The point
enameling and
glazed ceramics
from the shelf.
The wire mesh is referred to as an
enameling rack. An enameling fork lifts
the rack out of the kiln. A stilt separates
the piece from the rack.
Ceramic Bowl
You can purchase a clay/silica melting crucible from
Rio Grande (#704-120) that will last through many firings.
Use it to hold alumina hydrate.
enameling Rack
Please Note: Ceramic shelves and bowls and insulating
firebricks may slow the firing. They absorb more heat than
the ceramic fiber shelf and cool more slowly.
Enameling is the art of firing glass onto metal. The metal
shapes are arranged on a high temperature wire rack. The
enameled pieces and wire rack are loaded into a hot kiln,
fired for just a few minutes, and removed red-hot. To load
and unload the racks safely, use an enameling fork.
Glass Separator & Kiln Wash
Fiber Repair Filler
Glass separator and kiln wash are mixtures of finely ground
minerals that will not melt and
fuse together at high temperatures. They prevent glass and
ceramic glaze from sticking to
fireclay shelves.
Filler is a permanent, high-temperature refractory cement
used to repair holes or cracks in the ceramic fiber firing
The difference between glass
Safety Glasses
Wear safety glasses when cutting
or chipping glass and when looking
into a hot kiln. See your Rio Grande
Tools & Equipment catalog for safety
glasses. Caution: Always wear firing
glasses when viewing the oven’s
iMPortant guidelineS
To remove hot items
from the kiln, turn off
the kiln. Wearing thick
work gloves, carefully
slide an enameling fork
under the shelf. Lift out
the shelf and place the
hot shelf on a large
ceramic kiln shelf in front of the kiln.
The heating elements of your kiln are embedded into the
ceramic fiber firing chamber. The firing chamber surface
is hardened to a depth of 1/4". This makes the fiber more
durable. It is important that you do not touch the firing
chamber with sharp objects. These can penetrate the fiber
surface and contact the heating element, creating a severe
shock hazard.
• Type of pieces
Do not be concerned if your kiln makes a clicking sound
during firing. Your kiln contains a relay which sends power
to the element. The relay clicks as it cycles on and off to
maintain the correct temperature.
• Firing results
As you gain experience, you will find a wealth of useful
information in your firing logs.
A low-temperature hold (e.g.: 200°F–300°F) is more
difficult to maintain than a higher temperature hold
(1400°F–1700°F). At low temperatures, turning on the
heating element affects firing temperature to a greater
degree than at high temperatures.
The small rod protruding into the firing chamber is the
temperature sensor or thermocouple. The digital controller
senses temperature by reading a voltage from the thermocouple. Be sure the rod extends into the firing chamber
before firing the kiln. Please Note: If this rod is bumped
out of the firing chamber, the kiln will assume that the
firing chamber is cold. This will result in over-firing. The
controller does not contain an alarm to detect this kind
of failure. Always check placement before firing.
• A 1/8"-diameter thermocouple should extend into the
firing chamber 1/2"–5/8".
• A 1/4"-diameter thermocouple should extend into the
firing chamber 1" or more.
• Keep shelves, posts and objects being fired 1"–11/2"
away from the thermocouple.
Clean the kiln before firing glass, enamels or ceramic
glaze (cleaning is not necessary when firing PMC®). Use
a soft brush nozzle on a vacuum cleaner to remove dust
from inside the kiln.
Record the following information in a firing log book:
• Date
• Firing temperature, speed and hold time;
or Ramp/Hold program
• Starting time
• Total firing time
When holding at a low temperature, heat the kiln slowly
to avoid overshooting the hold temperature before the
element turns off.
Contact with silica or silica-bearing compounds (such as
kiln wash, glass separator, alumina hydrate, glass, enameling
powder or ceramic glaze), will ruin the heating element.
This type of damage is not covered by warranty. Never fire
glazed ceramic ware, glass or enameling directly on the
firing chamber bottom. Use a ceramic shelf on short posts
to protect the bottom from glaze drips, glass and enameling
Please Note: If a contaminant such as dripping glass or glaze
becomes embedded in the firing chamber, unplug the kiln.
Gently scrape off the contaminant with a knife, being careful
not to damage the heating element. Vacuum the kiln.
Firing PMC® leaves traces of silver in the pores of the firing
chamber. Sometimes there is enough silver residue in
the kiln to affect colors of glass. For instance, green might
turn yellow. Before firing an important glass piece in a kiln
used for silver clay, perform color tests. Fire small samples
of each glass color on a base sheet of clear glass. Place
the glass on a fireclay shelf (not the soft fiber shelf ).
Place Items on a Protective Shelf
Always protect the firing chamber by firing your pieces
on a shelf or in a bowl. Do not place the pieces directly
on the bottom of the firing chamber. See types of shelves
and containers on page 4.
Apply Glass Separator or Kiln Wash
Glass and ceramics are fired on a fireclay kiln shelf and
not directly on the kiln bottom. You can also slump glass
over a mold, such as a bowl. The kiln shelf and sagging
mold must be coated with glass separator to keep glass
or ceramic glaze from
sticking to them.
A coat of glass separator
or kiln wash will usually
last through several
firings. The lower the
fusing temperature,
the more firings you
Apply a new coat of separator when
can get from one
the old coat begins to flake.
application of separator.
When the shelf coating begins to crack or chip, apply a fresh
Before re-coating a shelf, remove as much of the old coating
as possible with a grit cloth so that you start with a smooth
surface. The abrasive mesh of the cloth allows residue to
pass through. Re-coat the shelf using the directions below.
Please Note: Both glass separator and kiln wash are referred
to as “separator.”
Important: Do not apply glass separator or kiln wash to
the ceramic fiber firing chamber or to the bottom of the
shelf! Contact with glass separator or kiln wash can ruin the
embedded heating element.
Please Note: Do not coat the soft ceramic fiber shelf with
separator. When firing glass with or without PMC®, above
1110°F, fire the piece on a hard fireclay shelf coated with
1. Follow the directions on the bag to mix the separator
with water.
2. Use a haik brush or a soft paint brush to apply the
separator to the shelf. The haik brush is recommended
because it lays down a more even coating.
3. Each time you dip your brush into the separator mixture,
swirl the brush around the bottom of the container to
re-mix the separator.
4. Use two or three thin coats, changing the direction of
your brush strokes 90° with each coat.
5. Dry the shelf before firing. To speed drying, place the
shelf on three or four 1/2" posts inside the kiln. Heat at full
rate to 300°F/148°C and hold for five minutes. Then turn
off the kiln and leave the shelf inside.
6. After the separator has dried and your shelf is cool, you
can smooth the separator further by rubbing your hand
lightly over the shelf. The smoother the separator, the
smoother the underside of your glass will be.
Use Ceramic Fireclay Posts
• Place three or four 1/2" posts under the hard ceramic
fireclay shelf to help air circulate, preventing heat built-up
under the shelf.
• You can fire two
or more ceramic
fireclay shelves
in the Rio PMC®
kiln. Separate the
shelves with taller
posts. The length
of the posts and
the number of
shelves you can fire depends on the size of the kiln.
Some types of pieces, such as glass and ceramics, contain
impurities that burn off during firing. These impurities must
be released from the kiln; otherwise, they can affect the
quality of the piece.
PMC® needs no venting unless you are firing it with
a material that burns out for a hollow shape, or are
combining it with another material such as glass.
Open the vent hole by removing the ceramic plug in
the top of the kiln.
Please Note: When the kiln is first turned on, the numbers on the display will show the software package that is
installed in your kiln—this is a normal operation.
Temperature Display
No Display Dot:
Temperature display, °F.
Time Display
Right Display Dot:
Temperature display, °C.
Center Display
Dot: Separates
hours & minutes.
For your convenience, five programs
for firing PMC®, PMC+® and PMC3® are
pre-set into the Rio PMC® controller:
Program 1: PMC+® Fast
Ramp — Full
Temperature — 1650°F
Hold — 10 minutes
Program 2: PMC+® Slow
Ramp — 1500°F
Temperature — 1470°F
Hold — 30 minutes
Start/Stop Key
Up Arrow Key
1) on/off: Starts
and stops a firing.
2) enter Data:
Press after each
programming step.
1) Increases values
during programming.
2) Select Mode: from
IdLE press start. Press up
arrow key to select PMC
or Ramp/Hold mode.
3) Skip Segment: During
Ramp/Hold firing, skips to
the next segment. After
pressing up arrow key,
SStP will appear. To skip,
press up arrow key again.
Down Arrow Key
1) Decreases values
during programming.
2) Review: From IdLE
or during firing, press
down arrow key.
The program will
appear one step
at a time.
3) Delay: From
Start press down
arrow key.
Rio PMC® kiln control panel descriptions
Program 3: PMC3® Slow
Ramp — 1500°F
Temperature — 1110°F
Hold — 45 minutes
Program 4: original PMC®
Ramp — Full
Temperature — 1650°F
Hold — 2 hours
Program 5: PMC® 22KY Gold
Ramp — Full
Temperature — 1290°F
Hold — 11/2 hours
You can customize programs to fire
materials other than PMC®, such as glass
and enamel. Enter custom programs using
any of the four user-defined settings.
If your controller shows a small dot in the lower right corner of the display,
the temperature shown is °C. If there is no dot, the temperature shown is °F.
To change the temperature display:
1. Unplug kiln or disconnect power.
2. Remove the four screws from the controller on the front of the kiln,
and carefully remove it, leaving the wires attached to the controller.
3. At the back of the controller, on
the circuit board, you will see a set
of connector pins labeled “C/F”. When
a jumper connects the two pins, the
display will read in °F. When the jumper
is removed, the display will read in °C.
Remove or insert the jumper as
desired (jumpers are available from
any computer supply store.
4. Re-install the controller, being careful
not to jar components on the back of the controller against the kiln case.
IdLE must appear before you can fire
the kiln.
• If CPLt, STOP or other messages
appear instead of IdLE when you turn
the kiln on, press the start/stop key.
IdLE will appear.
• If you press the start/stop key
during a firing, STOP will appear.
To get back to IdLE, press the start/
stop key again.
• If the display shows an error message
such as FAIL instead of IdLE, see
page 12.
• CPLt (firing complete) appears
at the end of a firing. To make IdLE
appear, press the start/stop key.
The up arrow and down arrow keys change number
settings during programming. Ordinarily, you would press
the up arrow key to raise a number and the down arrow
key to lower it. But sometimes it’s faster to press the
opposite key because the numbers scroll below 0000 to
the maximum setting and vice versa.
• To program a 99.59-hour Hold when the display shows
“00.00,” press the down arrow key once.
• To program a Full rate when the display shows “0000,”
press the down arrow key once.
• To program a temperature of 200°F when the display
shows “1800°F,” press the up arrow key.
Program review allows you to confirm that the program in
the controller is correct. It is a good habit to use program
review before every firing.
• Program Review During Firing: Press the down arrow
key. The rate, temperature, hold, etc. will display one after
the other; firing will continue.
• Program Review and Repeat Firing From IdLE: Press
the down arrow key. After rate, temperature, hold, etc.,
Strt will appear. Press the start/stop key. -On- will appear
and the kiln will begin firing the program just reviewed.
Hold maintains a steady temperature for the length of time
you specify. In the pre-set PMC® programs, Hold has already
been determined for you. In Ramp-Hold, you can use Hold
in both heating up and cooling down segments.
When Hold is set to 99.59 hours, the controller will remain
at that temperature indefinitely, until you press the start/
stop key. To enter a 99.59-hour Hold, press the Down Arrow
key once from “00.00” during programming in Ramp-Hold
(see page 9). Please Note: During firing, the Hold
temperature alternates with the remaining Hold time.
Delay is a count-down timer. The kiln begins firing when
the timer runs out of time. Use Delay to control firing
Caution: For safety, do not leave the kiln unattended during
a delay or a firing. You must be present to ensure that the
kiln turns off at the proper time.
1. After you have programmed the controller and it is
ready to begin firing, Strt will appear.
2. Press the down arrow key once. dELA will appear,
alternating with 00.00.
3. Use the arrow keys to enter the delay time (e.g.: 1 hour,
10 minutes = 01.10), then press the start key. dELA will
appear, alternating with time remaining before firing
After a power failure, the controller will continue firing
provided that:
• the temperature dropped no more than 104°F/40°C
while the power was down.
• the kiln temperature is above 212°F/100°C when
the power is restored.
PF 1 — Power failed during a cooling segment, and the kiln
cooled past the target temperature while the power was
PF 2 — Power failed during firing and the kiln temperature
was below 212°F/100°C when the power came back on.
PF 3 — Power failed during firing and the temperature
dropped more than 104°F/40°C by the time the power
came back on.
Unplug the kiln or disconnect the power when the kiln is
not in use, especially during thunderstorms and in areas
with frequent power surges. If the kiln is partially through
a firing when a storm begins, it is probably safe to continue
the firing. Do not leave the kiln unattended.
After a temporary power failure, or when the kiln has shut off
too soon, it may be necessary to turn the kiln back on. After
you press the start/stop key, the controller will begin firing
from the current temperature to the target temperature. In
Ramp/Hold, the firing will begin from the first segment that
encompasses the current temperature. Please Note: If the
kiln is already hotter than the programmed target temperature when you begin firing, CPLt will flash.
The controller needs three pieces of information to fire:
• Rate or Ramp
• Temperature
• Hold time (if any) at that temperature
This information has already been programmed into the
controller for PMC®, gold and silver. The PMC programs are
shown in the display window during program selection as
Programs 1, 2, 3, 4 and 5. The chart on page 7 shows the
firing rate, temperature and hold time for each PMC
program. The display prompt column shows the program
number to select for each type of PMC.
general firing
1. From IdLE, press the start/stop key
2. Use the up arrow key (not the down arrow key) to
select PMC® program 1, 2, 3, 4, 5 or PrOG (Ramp-Hold
mode programming: see next section). Then press the
start/stop key.
3. Strt will appear. Press the start/stop key to begin firing.
-On- will appear and the kiln will begin firing.
To stop a firing before completion, press the start/stop key.
StOP will appear, alternating with the kiln temperature.
Diagram 1: A single segment with a rate of 375°.
When the kiln fires to completion, the controller will beep
for 30 seconds. The display will show the following:
• Firing time
• Present temperature
• CPLt
To return to IdLE, press the start/stop key.
raMP-hold Mode
A segment is the most basic part of a firing in Ramp-Hold
mode. A segment includes a target temperature and a
firing rate (or ramp) to reach that temperature. The firing
rate is figured in degrees of temperature per hour. Shown in
Diagram 1 is a segment with a target temperature of 750°.
Diagram 2: Rate is degrees per hour.
Since, according to the chart, the temperature will take two
hours to reach 750°, the rate is 750 ÷ 2 = 375° per hour.
Diagram 2 (at right) illustrates three different rates. A rate
of 1000°/hr will reach 1000° in one hour. A rate of 500°/hr
will reach 1000° in two hours. A rate of 333°/hr will reach
1000° in three hours.
A segment (a target temperature and a rate of heating to
reach that temperature) can include a hold as shown in
Diagram 3. Hold means maintaining the target temperature
for a length of time. Firing to a temperature at a single rate
would need only one segment. Reasons to add segments
• To have more than one heating rate
• To add a hold somewhere below the shut-off
temperature (see Segment 1 in diagram below)
• To control the cooling rate
Diagram 3: A single segment with a one-hour hold.
Diagram 4 shows a 3-segment firing. The first two
segments are used to bring the temperature up to
a target temperature. The last segment represents
a controlled cooling.
Diagram 4: A 3-segment firing with controlling cooling.
Each segment must include a rate, which is degrees of
temperature change per hour.
The kiln will fire at full power when the rate is 1799°F/999°C.
Full power displays as FULL.
Please Note: To enter full power from 0000, press the down
arrow key once.
While the kiln is firing in Ramp-Hold, you can change
the target temperature for any segment during its firing
sequence. If the segment is in hold, it will come out of hold
and fire to the new temperature at the original rate. Please
Note: You cannot adjust the firing rate during firing. If you
wish to change the target temperature of a segment not
currently firing, simply wait until that segment begins and
then make your change. To edit the target temperature:
1. Press the Up Arrow repeatedly until CHGt appears.
2. Press START. The target temperature for the current
segment will appear in the display.
3. Use the arrow keys to change the target temperature.
4. Press START. The normal kiln temperature will appear.
You can avoid temperature over-shoot by slowing the rate
as shown below.
You can also avoid a temperature over-shoot by adding
a segment with a slower rate, to begin approximately 40°–
Example of Editing Target Temperature:
You program the kiln to fuse glass at a temperature of
1450°F. At 1445°F, you check on its progress and realize that
the glass will need at least another 50° to fuse fully. You can
change the target temperature to 1560°F without having to
turn off the kiln to reprogram it.
While the kiln is firing in Ramp-Hold, you can add five-minute increments of hold time to any segment during
its firing sequence (even if the segment has no hold time
programmed to begin with). This feature is designed for
ceramists who use witness cones and for glass artists
who inspect the glass near the end of firing.
1. Press the Up Arrow repeatedly until HLdt appears.
2. Press START. The hold time for the current segment will
appear in the display.
3. Press the Up Arrow once for each five-minute increment
of time you wish to add.
4. Press START. The normal kiln temperature will appear.
Heating a kiln at a fast rate (diagram at top right) may cause
the temperature to over-shoot the target temperature, especially in small kilns at lower temperatures. To avoid this, add
an extra segment in Ramp-Hold to slow the firing near the
target temperature.
60° below the target temperature.
While the kiln is firing in Ramp-Hold, you can skip from the
current segment to the following segment in a sequence.
1. During a Ramp-Hold firing, press the Up Arrow. SStP
will appear.
2. Press START. The current segment ramp or hold number
will appear. (If you change your mind and don’t want to
skip after all, simply don’t press START after SStP appears.
The firing will continue in the same segment and the
temperature will appear after one minute.)
3. Press START again.
Please Note: The skip-segment feature does nothing during
the final segment. To end the final segment, press STOP.
Example of Skipping A Segment:
You have programmed a target temperature of 1425°F for
fusing glass, followed by a segment for controlled cooling. When you check on its progress, you see that the glass
edges have rounded nicely at 1315°. Use the skip-segment
feature to end the firing segment and start the controlled
cooling segment.
Use the Ramp-Hold mode to program a slow cooling. Slow
cooling enhances the quality of some ceramic glazes; it
also encourages crystal development, deeper gloss and
sometimes startling color shifts. Iron red glazes seem to
respond well to slow cooling.
For controlled cooling, program a segment to a lower
target temperature than that of the preceding segment.
The controller, of course, cannot speed cooling beyond the
kiln’s natural cooling rate.
Glass artists sometimes flash-cool glass after it has fused.
They open the door slightly for a few minutes to allow
heat to escape. To flash-cool the glass, you will need to
add a segment with a rate of FULL. Otherwise, after the
flash-cool, the controller will raise the temperature again.
1° = slowest rate.
1799°F/999°C = full power.
Then press the start/stop key.
°F 1 (or °C 1) and segment 1 target temperature from the
last firing will appear. Use the up and down arrow keys
to change the temperature. Press the start/stop key.
HLd 1 and segment 1 hold time from the last firing will
appear (e.g.: 1 hour 10 minutes = 01.10). Use the up and
down arrow keys to change the hold time. Then press
the start/stop key.
Continue entering values for the segments needed. When
ra _ appears for the first segment you don’t need, select
0000. Then press the start/stop key to enter. This will
enter zero for any remaining segments.
Strt will appear. Press the start/stop key to begin firing.
-On- will appear and the kiln will begin firing.
To stop a firing before completion, press the start/stop key.
StOP will appear, alternating with kiln temperature.
Please Note: The actual firing rate may be less than the rate
you programmed, depending on the kiln model, available
voltage and the density of the load you are firing.
When the kiln fires to completion, it will beep for 30
seconds. The display will show the following:
• Firing time
• Present temperature
• CPLt
To return to IdLE, press the start/stop key.
the alarM feature
Caution: During fast cooling, do not open the lid or door
all the way. Do not flash-cool the kiln with a fan.
The above firing would be programmed as follows:
Please Note: If you don’t need all eight segments available
in Ramp-Hold, enter zero for each of the unused segments
(see step 6, below).
1. From IdLE , press the start/stop key.
2. Using the up arrow key (not the down arrow key),
bypass PrO1, PrO2, PrO3, PrO4 and PrO5. Select ProG
then press the start/stop key.
3. rA 1 will appear. Enter firing rate (temperature change
per hour) for segment 1.
You can set an alarm to sound when the kiln reaches the set
temperature during any PMC® or Ramp-Hold program. Use
the alarm, for example, to alert you to check the fusing or
slumping of glass.
Only one alarm temperature can be set at any one time;
however, after the alarm beeps, you can re-set the alarm
for another temperature. Re-set the alarm as many times
as you need during a firing program. Entering an alarm
temperature automatically overwrites the previous alarm
Please Note: The alarm temperature you set during a firing
must be higher than the current display temperature. The
alarm is designed for rising temperatures, not for cooling
1. During the firing mode, press the Up Arrow repeatedly
until ALAr appears.
2. Press START. The current alarm temperature will appear.
3. Use the arrow keys to set the alarm temperature.
4. Press START. The normal kiln temperature will appear.
To silence the alarm, press any key. An alarm temperature of
32°F/0°C will turn off the alarm.
power came back on.
error MeSSageS
tC (thermocouple failure) — The thermocouple failed
during the IdLE display. See the “Paper clip Test” under FaIL,
BAdP (bad programming) — The kiln will not fire because
1) the Ramp-Hold program entered has a rate of 0000 in
segment one, or 2) the target temperature in segment
one of Ramp-Hold is lower than the current temperature.
tCL (thermocouple lag) — The heating rate is slower than
9°F/5°C per hour and the kiln temperature is more than
100°F/56°C away from the programmed temperature. To
return to the IdLE display, press any key. Causes include:
• On kilns with a portable controller, the thermocouple
may have fallen out of the firing chamber.
• A bare spot on the thermocouple lead wires has
touched a grounded object inside the kiln switch
box causing the thermocouple to short out.
• tCL will flash if you program a cooling segment
temperature that is below room temperature.
etH — The temperature of the electronic circuit board is
above 158°F/70°C. This could damage the controller, so the
firing has been stopped. To correct and/or prevent this, keep
the firing room cooler. Increase ventilation.
FaIL (thermocouple failure) — The thermocouple
(temperature sensor) failed during firing. Possible causes
• Defective thermocouple or disconnected/loose wires
• Defective controller
• Electrical noise
Thermocouple Paper Clip Test
Check the thermocouple wire
connections (see page 5). If connections
are tight, perform this test:
1. Unplug the kiln or disconnect
the power. Remove the controller
(“Selecting,” step #2, page 7). Remove the two thermocouple wires from the back of the controller.
2. Clip off the U-shaped end of the paper clip. Insert it
(or another piece of thin wire) into the thermocouple
3. Plug in the kiln. If the controller displays room
temperature, replace the thermocouple. If it shows FaIL,
replace the controller.
Fe-5 — This signal appears when the controller senses an
inability to communicate, either within the controller or with
the oven. This can be caused by power fluctutations. Press
the keypad to reset the controller.
FtL (fired too long) — This message appears when both
of the following conditions occur:
• The temperature rise is less than 27°F/15°C per hour.
• The firing is four hours longer than programmed.
See “Controller display turns on. No heat in kiln,” page 13.
PF 1 (power failure 1) — The power failed during a cooling
segment, and the kiln cooled past the target temperature
while the power was off. The kiln will not resume firing. To
return to the IdLE display, press any key.
PF 2 (power failure 2) — The power failed during firing
and the kiln temperature was below 212°F/100°C when
the power came back on. The kiln will not resume firing. To
return to the IdLE display, press any key.
PF 3 (power failure 3) — Power failed during firing and the
temperature dropped more than 104°F/40°C by the time the
Check for worn or burned-out elements, defective relays,
low voltage and a defective thermocouple.
tCr (thermocouple reversed) — Thermocouple lead wires
are reversed. Check that the thermocouple lead wires are
connected to the correct terminals (see kiln wiring diagram).
diSPlay MeSSageS
Abrt — Firing was stopped.
ALAr — Ready for you to enter an alarm temperature. When
the kiln reaches that temperature, the alarm will sound.
CHGt — Ready for you to edit the target temperature of the
current Ramp-Hold segment during firing.
CPLt/COnE— Fired to completion.
dELA — Delay is a count-down timer that starts the kiln
when the time runs out.
°F or °C (with numerals) — The controller is ready for you
to enter the target temperature (the temperature that
the kiln will fire to). Each segment in Ramp-Hold has a
target temperature.
FULL — Full power firing rate. At this setting, the kiln will fire
at its fastest rate. To select full power, program a rate of
1799°F/999°C at the ra _ prompt in Ramp-Hold. A fast
way to do this is to press the down arrow key once from
0000. FULL will appear.
HLd 1 (with numerals) — Hold time of a segment. Shown
in hours and minutes. (example: 2 hrs., 15 mins. = 02.15).
HLdt — Add hold time. During a firing, you can extend the
hold time of a segment without having to first stop the
firing to reprogram the controller.
IdLE — The controller is ready for you to enter a program
or to begin a repeat firing.
-On- — Firing has begun. A moment after -On- appears,
you will hear the relay(s) clicking.
Pr (with numeral O1–O5) — Pre-programmed PMC® firing
sequences. Scroll through these prompts with the up
arrow key. Press the start/stop key to select the desired
PMC program.
ProG — Program. Select this option to manually program a
Ramp-Hold firing.
rA 1, rA 2, etc. — Rate. Appears in Ramp-Hold programming
for each segment. The 1, 2, etc., are segment numbers.
Enter the rate of temperature change for that segment.
Rate is figured in degrees of temperature change per
hour. Examples:
• A temperature rise of 100° in two hours = 50° rate.
• A temperature drop of 200° in one hour = 200° rate.
SStP — Skip step. This message appears when you press
the up arrow key during a Ramp-Hold firing. If you
press the up arrow key again, the firing will skip to
the next segment.
StOP — The firing was stopped by pressing the
start/stop key.
Strt — The “Ready to Start” message appears after programming a firing. Press the start/stop key to begin firing.
Controller calibration (press the Up Arrow) and delay
(press the Down Arrow) functions are accessed from
the START message.
TCOS — Calibrate the controller to fire hotter or cooler.
• Is the kiln connected to the power?
• Has the circuit breaker tripped or is a fuse blown?
• Is power reaching the wall receptacle? Test with a
voltmeter or a test light if you are not sure.
• Has the kiln switch box 1/2-amp
fuse blown?
The kiln’s 1/2-amp fuse is
located in the kiln switch box.
Remove it by pressing the fuse
holder and turning counterclockwise half a turn. Check
the fuse by placing the probes
of an ohmmeter on the ends
of the fuse. If the ohmmeter reads less than one ohm
(digital meter) or reads 0 ohms (analog meter), the fuse
is working. If the reading is OPEN (digital meter) or
infinity/no needle movement (analog meter), the fuse
is defective. Replacement fuse: AGC 1/2 A 250V AC.
• Is the controller receiving power? Test the power
input connections on the back of the controller with
a voltmeter.
Controller Power Input Test #1
1. Unplug the kiln. Remove the four screws holding the
controller faceplate to the switch box. Lift the faceplate
out of box and let the board
hang on the box with the back
of the board facing you.
2. Plug the kiln back in.
Touch voltmeter probes
(in AC mode) to both input
connections (the white and
orange wires).
Caution: Do not let the back of the board touch a
grounded object. Make sure the voltmeter is in the AC
mode when placing the probes on input connections.
• Controller Power Input Test Result: No voltage
Unplug kiln. Check the switch box for disconnected wires
between the cord, transformer and controller. If the wiring
is sound, replace the transformer.
• Controller Power Input Test Result: 20–24 volts AC
Correct current is reaching the board from the transformer. Since the board is not lighting up, it is probably
defective. Return the controller for repair or replacement.
• Controller Power Input Test Result: Less than 20 volts
Did you recently replace the transformer? It may be the
wrong voltage. The voltage is below 20, which is not
enough to power the controller. To find out the cause
of low voltage, continue below:
Controller Power Input Test #2
The back of the board is still
facing you and the kiln is
plugged in. Remove the input
plug (the white, orange and
blue wires) from the back of
the controller. Touch a voltmeter
probe to the white wire and the
other probe to the orange wire.
• Input Test #2 Result: Less than 20 volts AC
There are two possible reasons: 1) Low voltage at the wall
receptacle; 2) a defective transformer. If wall receptacle
voltage is correct, replace the transformer.
• Input Test #2 Result: 20–24 volts AC
The transformer is sending correct voltage to the
controller. Yet when the input plug was connected to the
controller, the voltage was less than 20. This means the
controller is draining the voltage and is defective. Return
the controller for repair or replacement.
• Is the relay making its normal clicking sound?
If yes, test the elements with an ohmmeter.
Element Resistance Test
1. Unplug the kiln/disconnect the power. Open the kiln
switch box. Make sure the wires connecting the relay to
the elements are secure. If the connections are sound,
continue to step 2.
2. Touch the ohmmeter leads to the two element
connectors of each element. A no-needle-movement
reading on an analog meter (or OPEN on a digital meter),
is done
indicates a broken element.
If the elements check out, replace the relay (see page 23
to replace relay).
If no:
We know the controller is receiving voltage because the
display is lit. But the voltage from the transformer may be
too low to power the relays. Perform the “Controller Power
Input Test #1” (page 13). If your controller passes the input
test, perform the “Controller Power Output Test” below.
Controller Power Output Test
1. Unplug the kiln/disconnect the power. Remove the four
screws holding the controller faceplate to the switch box.
Lift faceplate out of box and let the controller hang on the
outside of the box with the back of the board facing you.
Then plug the kiln back in. Program the controller to fire
to 1000°F at FULL rate in Ramp-Hold mode. Press the
start/stop key.
2. Put the voltmeter in DC mode (it must be in DC mode
when testing output voltage). Touch probes to the red
wire and black wire connections. Measure the voltage
when the relay clicks on.
• Output Test Result: No voltage at red and black wires
If the fuse blows, replace the transformer. If the fuse does
not blow, the problem is a board or relay. Go to step 2.
2. Connect the input plug (orange, blue and white wires)
to the board again. Leave off the output wire plug (red,
green and black wires). Program the controller to fire to
1000°F at FULL rate in Ramp-Hold mode. Press the
start/stop key. If the fuse blows, replace or service the
board. If the fuse does not blow, the problem is caused
by a short in the coil of a relay. Go to step 3.
3. Unplug the kiln/disconnect the power. Reconnect the
output wire plug. Reinstall the board in the switch box.
Replace the relay (see page 23).
Ramp-Hold Shorthand Instructions
Re-read the safety guidelines on page 2. After you press
Keys to Press
select ProG
The controller is sending correct power to the relay.
Unplug the kiln/disconnect the power. Remove the kiln
witch box. Look for disconnected wires between the
controller, relay and elements. Check the wiring diagram
to be sure wires are connected to the correct terminals.
Be sure connections are tight. If the wiring is sound,
replace the relay. To replace relay, see page 23.
• What size fuse are you using? Correct fuse:
AGC 1/2 A 250V AC.
• If the fuse is the correct size, perform the following test:
Kiln Switch Box 1/2-Amp Fuse
Power Test
1. Unplug the kiln/disconnect
the power. Remove the four
screws holding the controller
board faceplate to the switch
box. Lift the faceplate out of
box and let the board hang
on the out side of the box with the back of the board
facing you. Then plug the kiln back in. Disconnect both wire
plugs from the back of the controller. Apply power to kiln.
rA 1
enter segment 1 rate
500 (sample rate)
°F 1 or °C 1
The controller is not sending power to the relay. Return
the controller for repair or replacement.
• Output Test Result: 10–14 volts at red and black wires
enter temperature
you want to fire at
1900 (sample temp.)
enter hold time
00.00 (or hold time)
First segment not needed: enter a rate of 0000.
the keys in the left column, the message in the center will
appear. For more detailed instructions, see pages 9–11.
PMC® Shorthand Instructions
Keys to Press
PrO1 - ProG
select 1–3
PrO1 = PMC+ Fast
PrO2 = PMC+ Slow
PrO3 = PMC3 Slow
PrO4 = PMC Original
PrO5 = PMC Gold
-On- (the kiln is
now firing)
Re-read the safety guidelines on page 2. After you press
the keys in the left column, the message in the center will
appear. For more detailed instructions, see page 9.
PreciouS Metal clay®
If the piece needs only shallow support (1/4" depth or less),
pour the alumina hydrate onto a ceramic fireclay shelf.
Support the fireclay shelf on three or four feet to aid heat
flow under the shelf.
If the PMC® shape needs deeper support, pour the alumina
hydrate into an unglazed ceramic bisque bowl.
With PMC®, it is possible to shape intricate, free-form
silver or gold jewelry in minutes—even as a beginner.
• NEVER use a glazed bowl to hold the alumina hydrate.
If the glaze runs, it can embed into the firing chamber.
PMC looks and feels like modeling clay. It is formed
with simple tools such as a toothpick, small knife and razor
blade. Its surface is pliable and accepts impressions from
objects such as leaves, coins and coarse fabrics. After PMC is
formed, it is fired in a kiln. The recommended temperatures
and hold times are included with PMC.
Caution: Avoid inhaling alumina hydrate dust.
PMC is made of micron-size silver (or gold) particles held
in an organic binder. During firing, the binder burns away.
The silver particles then fuse together forming pure silver.
Since the binder disappears, there is a certain amount of
shrinkage during firing. Shrinkage varies depending on
the type of PMC you use.
PMC® by itself needs no venting. Load the kiln, close the
door and leave it closed until the PMC is ready to remove.
Small, thin PMC® pieces can be placed into the kiln and fired
while still moist. Thicker pieces need time to dry or they may
warp during firing.
To be on the safe side, give PMC plenty of time to dry. As
you gain experience, you will know just how much drying
time each type of piece
needs. You can speed drying with
a hair dryer.
PMC® pieces that have
a flat side can be placed
inside the kiln directly
onto a shelf.
• PMC pieces can be close together, but
they must not touch.
• The soft ceramic fiber shelf can be placed directly
onto the firing chamber bottom. Four ceramic feet
are included to raise the shelf off the kiln floor.
• Do not coat the ceramic fiber shelf with kiln wash or
glass separator.
• You can also place PMC on a piece of ceramic fiber
Rounded, hollow or other delicate shapes may need
support to prevent collapsing. You can lay these pieces
onto a mound of alumina hydrate.
Caution: Alumina hydrate can destroy the heating element
on contact. If it spills into the firing chamber, remove with a
vacuum cleaner.
The kiln needs venting if you fire ceramics or glass with the
clay silver, or if you make hollow objects that contain a core
of organic materials.
Cork clay is a good core material. Do not use wax or
styrofoam as a core; they emit harmful fumes. When using
cores, vent the kiln by removing the plug from the top.
Each type of silver clay fires to a specific temperature and
hold time. This information is available from your silver clay
supplier (see page 7 for PMC® information).
Please Note: Do not fire longer than the recommended
hold, or the silver will begin to over-fire.
Besides selecting a temperature and hold time on the digital
controller, you will also need a firing rate. Select a full power
rate if you are firing PMC alone. If you fire glass or ceramics with the PMC, select a rate best suited for the glass or
Do not place PMC into a kiln that is already hot unless
the clay is completely dry. The kiln should be no hotter than
500°F/260°C when loading the PMC.
Once the kiln begins firing,
leave the door closed. Do not
open the door until it is time to
remove the clay. Visual inspection of the clay is unnecessary.
If you are firing glass with PMC,
you may need to check
Always wear safety glasses
the fusing progress of the
when looking at hot glass.
glass by opening the door
1/2" and looking inside (always wear safety glasses). Look for
just a second or two. As you
gain experience, you will be
able to program the correct temperature for your PMC
and glass combination,
eliminating the need to visually check the glass.
• Reservoir glass cutter uses a reservoir of oil to lubricate
the cutter wheel.
• Running pliers cut large pieces of glass.
• Breaking pliers cut small strips.
After the clay silver has fired to completion, you can open
the door an inch to speed cooling. If you are firing stones,
glass or other materials with PMC®, it is safer to allow the
kiln to cool slowly with the door closed. Remove the piece
when the kiln reaches room temperature. PMC pieces that
contain no other materials can be removed from the kiln at
1100°F/593°C. Use tongs to remove them and drop them into
Caution: Turn the kiln off before inserting tongs into the
firing chamber. Wear protective gloves.
coMbining PMc®
With other MaterialS
There are two ways to fire PMC® with other materials such
as glass:
• Fire PMC first by itself. After you have cleaned and
polished the PMC, fire it a second time with the
other material.
• Fire PMC and other materials, such as a stone, together
in a single firing.
Enameling powder is easier to fire with PMC in a second
firing (see page 18). Glass is often fired with PMC in a single
firing. Many types of glass will melt to the point of over-fire
at PMC temperatures. Before combining glass and PMC
in a single firing, test a small sample of the glass. To do this,
fire the glass during a PMC firing, keeping the glass separate
from the PMC (this way you won’t ruin the PMC piece).
Place the glass pieces on a ceramic fireclay shelf. You must
coat the shelf with glass separator, or the glass sample will
embed into the shelf.
If the glass sample withstands the firing, you can fire that
type of glass with PMC in a single firing. Note, however, that
different types of glass fire to different temperatures.
Every time you fire a different type of glass, be sure to test.
You will probably fire primarily stained glass, but you can also
fire standard float (window) glass. Some types of float glass
devitrify (form a dull, frosty surface) when fired. Caution:
Never fire tempered glass; it could explode if
heated inside a kiln.
Basic Glass Tools
• Grozing pliers shape the glass by chipping away the
edges. They are often used when the score line doesn’t
break cleanly. Note that rough edges will become smooth
when fired to fusing temperature.
Cutting Glass
IMPORTANT! Always wear
safety glasses when cutting
or chipping glass.
1. Lay the glass on a clean
surface. Mark the cut with
a grease pencil or felt-tip pen. A small mark on each end
of the glass will do. Lay a wood straight-edge over the
glass and line it up with the marks you made.
2. Hold the straight-edge
and score the glass with
the glass cutter. Press just
hard enough so that the
scoring sound is steady
and unbroken.
3. Place the straight-edge
under the glass so that
an edge is lined up with the score line you made. Press
down on the glass.
It will break cleanly.
Fusing Compatibility of Glass
When the temperature of glass changes, it expands
and contracts. The rate at which this occurs is called
the “coefficient of thermal expansion.” If you fuse two glass
pieces together and one changes size faster or slower than
the other, the fused piece may crack—even several months
after fusing.
When different glasses have similar enough coefficients
of expansion to fuse successfully, they are called “fusing
compatible.” Buy glass labeled “fusing compatible,” or fuse
glass that has been cut from the same sheet, which
guarantees compatibility.
Fusing Compatibility Test
1. To test glass for compatibility, fuse small 1/2"-square
sample pieces of different glasses onto a larger base piece
of clear transparent. The base should extend beyond the
small sample pieces by half an inch on each side. One of
the sample pieces should be cut from the base piece.
2. Heat the glass to a temperature that completely rounds
the edges of the small sample pieces.
3. After the glass cools, place a polarizing filter under the
glass and another filter over the glass. Look at the glass
with light shining through it (hold it over a lamp). Turn
one of the filters until the filters are at their darkest.
Loading the Kiln
Ensure that air circulates between the shelf and
the bottom of the kiln by placing three or four 1/2" posts in
the kiln. Lay the shelf over the posts.
Results of the Test
Firing the Glass
A halo around the edges of the small glass samples usually
means the glass is not compatible. If you don’t see a halo,
the glass is fusing compatible.
1. Vent the kiln by removing
the vent plug from the top
of the kiln. Venting allows
the gases released to
escape. When the kiln
reaches 500°–800°F/260°–
426°C, replace
the plug.
The sample square cut from the base transparent glass tests
for annealing. A halo around that piece means the glass was
not annealed properly. Perform the test again, this time
cooling more slowly through the annealing range.
The Annealing Range
Each type of glass has a temperature range that it must
pass through slowly as it cools. This is called the “annealing
range.” This slow cooling gives hot glass time to release the
stress of cooling. If you cool the glass too fast through the
annealing range, it will break.
Always wear firing safety glasses
when looking at hot glass.
2. The first time you fire a particular brand or type
of glass, program the
controller for a higher temperature than the
estimated fusing
temperature. Watch the glass by opening the door 1/2"
for several seconds at a time. Shut the kiln off when the
glass fuses the way you want. Make a note of the shut-off
temperature. For future firings, program the kiln for that
temperature and rate.
The larger and thicker the glass, the slower it must pass
through its annealing range. You cannot over-anneal, so
err on the side of caution if you aren’t sure how long to
anneal. Small projects such
as earrings rarely need
annealing time as they cool.
Please Note: With every firing, be sure you are near the kiln
before the expected shut-off time.
Cleaning and Gluing the
3. After you shut the kiln off, vent the kiln by opening the
door 1" for five minutes. Then close the door.
Grease, dirt and fingerprints
etch permanently into glass
during firing. Clean glass
with glass cleaner (the type
without silicones), rubbing alcohol or even plain water just
before assembling the pieces on the kiln shelf.
Use white glue (such as
Elmer’s) diluted 1:1 with
water to hold the glass
pieces together after you
place them on the kiln shelf.
Use the glue sparingly. Glue
is especially important when fusing wire into the glass. The
glue prevents the glass or wire from moving out of place
before they fuse. The glue disappears during firing.
Avoid using glue on the coated side of dichroic glass.
If you lay dichroic glass carefully onto the piece, glue is
unnecessary, so avoid it altogether if you do not know
which side of the dichroic
glass is coated.
Please Note: Some glass artists flash-cool the glass after
it fuses. To do this, vent the kiln until the temperature
drops to 1000°F. Then close the door again. This speeds
4. The annealing range for
most glass is between
950°F/510°C and
700°F/371°C. Cool slowly
through this annealing
range. Leaving the door
closed will slow the cooling enough for most projects. If you need even
slower cooling, program a separate segment for cooling.
Please Note: For safest cooling, leave the piece inside
the kiln until the kiln cools to room temperature.
If you remove the piece too soon, the sudden
temperature change
can crack the piece.
To remove small pieces, such as glass jewelry, before they
have cooled completely, remove the entire shelf.
Leave the pieces on the shelf until they reach room
temperature. The heat in the shelf will help prevent them
from cooling too quickly.
Caution: Before removing a shelf, turn off power to the kiln.
Preparing the Copper
Enamels come in transparent or opaque varieties. Start with
one of the many pre-shaped copper forms available, or
shape and trim copper to your own design.
1. Heat the copper on an enameling rack to about
1400°F/760°C to burn off any oil or
grease. Heat the
copper just until smoke from oil or
grease stops coming off the metal and
its color has changed to a purple/ red/
pale green iridescence that extends
across the
copper. This indicates that the grease has vaporized. Do
not fire the copper any longer than this point, or excess
firescale will form, making the cleaning step difficult.
2. After the copper cools, brush any loose scale from the
copper. Use a brush or paper towel, being sure that you
do not put any grease or oil, such as
fingerprints, onto the copper. Clean the copper with a
3M ScotchBrite® pad. This pad does such a good job
that in most cases, no further cleaning will be required.
Additional copper cleaning products like
Rio Pickle™ are available in the Tools & Equipment catalog.
It is best to clean the copper just before you decorate it.
If you wait too long to decorate after cleaning, the copper
will become dirty again.
Decorating the Copper
Counter- or backing-enamel, a mixture that gives a mottled effect, can
be used for counter-enameling, or
you can use regular enamel.
Most enameled pieces should be
counter-enameled on the back side.
This gives the piece a much more
finished look, eliminates a great deal of fire-scale cleaning,
and controls the chipping and cracking that can result from
the different rates of expansion and contraction in copper
and enamel after the enamel has been fired.
When firing counter-enamel,
under-fire it so that the firescale
on the front of the piece isn’t too difficult to remove. You can
purchase a masking preparation from your supplier to help
prevent fire scale. You must place the piece on a stilt when
the front side of the piece. The stilt prevents the back
of the counter-enameled piece from sticking to the
enameling rack.
Applying enamels
Apply enamel over a clean sheet of paper so you can pour
the excess back into the bottle for re-use. Transparent
enamels should be applied in several thin coats. Transparent
enamels can be mixed with fairly good results. Mixing
opaque enamels results in a grainy effect. The two basic
methods of applying enamels are sifting and spatula.
Sifting enamel
Spray or brush Thompson holding agent onto the copper.
Then sift a 1/32" layer of enamel onto the copper. Use a #60
mesh sifter. If the coat is too thin, you can easily add another
coat after firing, but a coat that is too thick will bubble and
crack. The enamel must dry completely before firing.
Spatula or Inlaid Method
You can use this method to decorate a small area with many
different colors. Using a diluted solution of Thompson holding agent, dampen the enamels just to the saturation point,
and maintain this moisture while working with the enamels.
Apply the enamels onto the copper with a small spatula,
and spread them out to a thickness of about 1/32" thick with
a spreader. Lines of contact can be formed by the
spatula blade. Then spray the enamels with the holding
agent to keep the grains of
enamel in place. Allow the
enamel to dry completely
before firing.
Firing Enamel
1. Heat the kiln to
1450°F/787°C for most enameling. Use a single segment.
2. Lay the copper form
on an enameling rack.
If the part that touches the rack is enameled, place a
stilt under the copper. Some bowls or other shapes have
enameled sides that might run during firing. These should
be fired with a stilt even if the piece has a plain bottom.
Use an enameling fork or, if the rack
is small, a 6" putty knife, to place the rack into the kiln
on top of 1/2" ceramic posts.
Please Note: Firing the piece at enameling temperature
should take about three minutes and requires your
undivided attention!
3. Look at your piece every 15 seconds by briefly opening
the door 1/2". Remove the rack when the copper piece
appears a rosy red and the enamel is smooth. Place
the rack on a steel pad or large ceramic kiln shelf and
let it cool completely.
4. After counter-enameling, clean
the firescale off the front of the
piece. A 3M ScotchBrite® pad
works well for this. Then clean it
with Rio Pickle™.
A self-supporting cone
fired to maturity
(do not be concerned if
the tip is slightly higher
or lower than shown).
Pyrometric Cones
Pyrometric cones are small pyramids
of clay and mineral oxide that soften
and bend when exposed to heat.
They indicate when ceramic has fired
to maturity.
Pyrometric cones come in 11/8"
and 21/2" lengths; use the 21/2" cones.
Cones mounted on the kiln shelf
must be slanted 8° from vertical.
They will not bend accurately if they
slanted to the wrong angle. Selfsupporting large cones have the
correct slant built into their bases.
Standard cones must be mounted
in a clay or wire plaque.
stilt and make sure no piece is
touching any other piece. Ware
must be completely dry before
China paints will crack or peel if
applied heavily. Apply
several light coats instead, firing
after each, until you get the shade
Open the door 1/2" to vent
the kiln if your kiln does
you want. Not all china paint colors
not have vent holes.
reach maximum color saturation
at the same temperature—even
when fired on the same piece—so you must know which
colors you should fire first at higher temperatures to prevent
Temperature equivalents for orton
Self-Supporting Pyrometric Cones
An over-fired cone with
“puddled” appearance.
Self-Supporting Cones
Heated at: 27°F/hr.
An under-fired cone.
The temperature equivalents chart
at right shows the temperatures
of pyrometric cones. Program
your controller for the cone
recommended for the ceramic
ware that you are firing.
light blue
*Rate of temperature increase during last 90–120 minutes of firing.
Tables courtesy of the Edward Orton, Jr. Ceramic Foundation.
Loading and Firing Overglaze
burning out other colors in later firings. For example, reds
mature at
a lower temperature than other colors and are fired after
the other colors have been fired. Reds and yellows should
not be fired side by side.
Colors also mature at a lower
temperature on ceramic pieces than on porcelain or hard
china. Check the literature from your overglaze manufacturer for
information on which cone to
use with each color and type
of ceramic ware.
Overglaze is decoration applied over fired glaze or polished
porcelain bisque. Overglazes include china paints, gold and
luster, which fire from cone 022 to 014. Load overglazed
ware the same way you would load ceramic glaze. Use a
Vent the kiln during the first hour of firing by leaving the
vent hole open during the entire firing. Allow kiln to cool to
temperature before opening the door.
For small ceramic pieces, such
as figurines, program a rate of 400°F/222°C. Fire to the temperature shown in the 108°F column of the temperature
equivalents chart for
the cone number you are firing.
Before selecting a firing speed for important pieces, test-fire
sample clay pieces.
Please Note: Do not fire beyond the maximum temperature.
Doing so will void your warranty.
loSt-Wax burnout
• Segment 3 lowers temperature to 800°F/426°C, the typical
casting temperature for silver. Most types of gold cast at
• Only kilns with vent holes are designed for lost-wax burnout. You can use a kiln without the vent hole
provided that you open the door 1/2" during firing.
Note: Casting temperature depends on the size of the mold.
The temperatures above are only a guide. See your jewelry
supply dealer for temperature recommendations.
• Always use a wax tray.
Burnout Instructions
• If your kiln heating element is embedded in the floor
of the firing chamber, place the metal wax tray on three
or four 1/2" posts inside the kiln to prevent any possibility
of the element shorting out against the tray.
1. Place a metal tray inside the kiln on three or four 1/2"
posts. Place the mold (sprue hole down) on a wire mesh
screen on top of the tray. The tray will catch melting wax
as it drips from the sprue hole.
Please Note: These instructions apply to injection wax
that melts at 200°F, not pattern waxes and plastics that
melt at higher temperatures. If smoke appears during wax
elimination, turn off the kiln. Smoking wax means the kiln
fired hotter than 300°F/148°C.
2. Keep the kiln vent hole(s) open during wax elimination.
This allows fumes to escape from the kiln. Heat the kiln
to 300°F/148°C and hold it at that temperature for at
least one hour.
Lost-wax casting is the process of carving a shape in wax,
then casting that shape in metal. After the wax has been
carved, a mold is made of the wax shape. The mold is a
negative image of the wax. The wax is later melted out
of the mold through hollow channels called sprues.
Lost-wax burnout is the process of preparing a casting mold
for the melted metal that will be poured into it. The steps in
lost-wax burnout:
1. Melt the wax from the mold.
2. Remove wax from the kiln before raising the temperature
higher than 300°F/148°C.
3. Harden the mold at high temperature.
4. Maintain the mold at the casting temperature
recommended for the type of metal that will be poured
into the mold.
Please Note: During this hour, the wax will melt from
the mold and drip into the tray. If the kiln gets hotter
than 300°F/148°C, the wax may smoke and deposit
carbon inside your kiln, causing expensive damage.
3. After one hour at 300°F/148°C, open the kiln. Remove the
mold and wax tray. Pour the wax from the tray and leave
the tray out of the kiln until your next wax elimination.
IMPORTANT! Do not leave the tray in the kiln!
4. Heat the mold to the temperature recommended by the
jewelers’ supply house where you purchased the mold
material. This is usually around 1350°F/732°C.
5. Lower the temperature to the casting temperature of
the metal. Hold at that temperature until you are ready
to begin casting. Remove the mold with tongs. Wear
protective gloves and safety glasses.
Saving a Carbon-Damaged Kiln
Caution: Prevent wax or carbon from contacting the kiln
walls and elements. Carbon build-up inside a kiln ruins the
interior. Carbon conducts electricity and causes elements to
short-circuit. Damage to elements from contact with foreign
materials is not covered by warranty.
If you follow the above directions, your kiln should be safe
from wax damage. In some cases, a small amount of carbon
may form on the walls over a period of time. This is due to
the burning of wax residue that was left in the mold. For this
reason we recommend that you periodically fire the kiln to
1500°F/815°C as follows:
A Sample Program
1. Open the vent cover(s) or leave the door ajar 1/2".
2. Fire the empty kiln to 1500°F/815°C at a rate of
300°F/166°C with a one-hour hold (01.00).
• Segment 1 heats the wax to 300°F/148°C and holds it
for one hour, allowing it to drip from the mold.
• Segment 2 hardens the mold.
firing MiStaKeS
Cracks that appear in fired PMC® may be due to too much
water in the PMC before it was fired. Another cause is
careless handling of a dried, unfired piece. To repair, fill
the crack with silver clay and fire again.
PMC® will not reach full strength if under-fired. You may
be able to save the piece by firing again to the correct
temperature and hold.
100°F/55°C below fusing temperature for 15 minutes. This
gives the shelf time to heat up to match the temperature
of the glass.
Glass Devitrification (Frosty Surface)
Too Much Shrinkage
Probable causes:
When PMC® is over-fired, it shrinks too much and loses
detail. If the kiln is firing hotter than the temperature
programmed, check the position of the thermocouple
(see page 5). Replace the thermocouple if necessary.
• Impurities in glass
Glass Cracking
Probable causes:
Devitrification is a frosty surface on the glass; with some
glass, it is unavoidable. To lessen devitrification, some artists vent the door of the kiln slightly after fusing is completed, then close the door when the temperature reaches
Glass Separator Sticks To Glass
• Heating the kiln too fast
Probable causes:
• Cooling the kiln too fast
• Firing too hot
• Fusing incompatible glass
• Not enough glass separator
on shelf
• Kiln not vented long enough during initial heating
Flaking glass separator can
cause the glass to crack.
This is because the glass
sticks to the shelf.
Most problems in fusing are
caused by rushing the firing. The
glass must change temperature slowly during the
critical temperature range of 100°–500°F/37°–260°C. This
critical range applies to both heating and cooling.
The second critical temperature range is annealing, which is
the cooling range of 950°–700°F/510°–371°C on the average.
Cool the glass slowly during this range so the stress in the
glass will have time to dissipate.
If you become impatient after the glass has fused and you
crack open the door of the kiln for a few seconds to peek
inside, you may hear a “ping,” which is the sound of glass
cracking. Avoid the temptation to open the door. Wait until
the kiln has cooled to room temperature. Some artists schedule their fusing so that it is completed before they go to bed.
That way they will be asleep while the glass cools and won’t
be tempted to open the door.
• Overglaze on the back of the piece
Instead of firing to a full-fuse temperature, try firing
50°F/28°C cooler and holding at that temperature for
several minutes.
Ceramic Overglaze
Breaking in overglaze Firing
Probable cause:
• Poorly fired bisque
A slow bisque fire is always better for ware that is to be china
painted. The greenware should be completely dry before
being placed in the kiln.
Purple Spots in Gold
Probable cause:
• A thin application of gold or too much thinner
If gold is applied accidentally to an area it will show purple
after being fired unless cleaned with a good gold remover.
Broken Lines in Gold
Probable cause:
After each firing, examine the shelf. Recoat if the kiln wash
is chipped. When glass sticks to a bare section of shelf, the
glass cracks.
• Over-firing or too heavy an application
Glass Bubbles
Peeling China Paint
Probable causes:
Probable cause:
• Heating the kiln too fast
• Applying the paint too heavily
• Air trapped between layers of glass
Loss of Color in China Paints
• Grease or dirt between layers of glass
Probable cause:
• Uneven glass volume
• Over-firing or thinning your paint with too much medium
when applying
• Moisture or trapped air between the glass and shelf
Make sure the shelf is completely dry before firing. If you
have applied fresh glass separator, leave the shelf in the kiln
at 300°F/148°C for 20 minutes before placing glass on it.
One way to eliminate bubbles is to hold the temperature at
However, this can be very attractive when gold is crackled
over a dark-color fired glaze.
Faded Colors in overglaze Decals
Probable cause:
• Either under-firing or over-firing
If pinks and reds are drab, re-fire to a hotter cone. When used
with a china paint background, apply and fire the decals
first, then china paint and fire again. Check the recommendations of decal supplier. If decal was under-fired, re-fire to
proper firing cone. If decal was over-fired, the design may be
repainted in china paints and re-fired.
Weakening of Luster Colors
Probable cause:
• Over-firing
White Spots in Lusters or Metals
Probable causes:
• Moisture on the ware before
it was placed in the kiln
• Was fired at the same time
as other overglazes
Please Note: Apply lusters only
on a dry day.
Powdering of Luster Colors
Probable cause:
• Too heavy an application
Kiln Does Not Turn On, Display is Blank
• Make sure the circuit
breaker is in the “on”
• If the circuit breaker is
on, check the kiln fuse. Remove the fuse by
pressing on the fuse
holder and turning
counter-clockwise half
a turn. Check the fuse by
placing the probes of an ohmmeter on the ends of the
fuse. If the ohmmeter reads less than one ohm (digital
meter) or reads
0 ohms (analog meter),
the fuse is bad.
Replacement fuse: AGC
1/2 A 250V AC
Please Note: If you do not
have an ohmmeter, look closely at the fuse. You will see a
thin strand of unbroken wire in a good fuse. The wire usually
appears broken in a bad fuse.
Circuit Breaker Trips
• If the circuit breaker trips after
the kiln has fired for a while,
make sure no other appliances
are operating on the same circuit as the kiln.
• If the circuit breaker trips
immediately after the kiln is
turned on, the kiln may have
a short-circuit. Unplug the kiln. Remove the bottom cover
and look for a loose wire touching the case.
Temperature is Inaccurate
• Make sure the
thermocouple is pushed 1/2"–
3/4" into the firing chamber.
• If the thermocouple is pushed
into the firing chamber, and
the temperature is inaccurate,
replace the thermocouple.
Door Latch Adjustment
Adjust the two screws on the
door latch to change the spring
Please Note: Do not loosen
the screws too far or they may
fall out.
Ceramic Fiber Repair
If glass, ceramic glaze or other
materials drip into the firing
chamber, repair before the next
firing, otherwise the glaze will
re-melt and embed deeper into
the fiber.
1. Unplug the kiln.
2. Cut or scrape the ceramic
to remove contaminant.
Remove as little fiber as
possible. Avoid touching any
heating element.
Replacing the
1. Unplug the kiln.
2. Remove the four screws holding the controller to
the front of the kiln. Carefully
remove the
10.Attach the wires to the back of the
controller. One wire is yellow, the
other red. Make sure the wires connect to the
color-coded terminals.
3. Remove the two
thermocouple wires from the
To prevent over-firing, the
must secure the thermoback of the controller. They
are held in place by button- or
connectors. To remove the wires, lift the levers (or press
the connector buttons) and pull the wires out.
11.Install the controller and back
cover of the kiln.
4. Remove the back cover
of the kiln.
5. The thermocouple is located in the back of the firing
chamber, held in place by a metal band. Remove the thermocouple from the kiln.
6. Bend the new thermocouple between the two porcelain
insulators. After bending, the thermocouple end should
be two insulators long.
7. Push the new thermocouple
into the hole in the firing
chamber. The twisted end
must extend into the firing
chamber by 1/2"–3/4". Make
sure the band holds the
thermocouple; otherwise,
thermocouple can be pushed out, resulting in an over-fire.
8. Thread the thermocouple wires down to the controller
opening at the front of the kiln. Keep the thermocouple
Replacing a Relay or Transformer
1. Unplug the kiln.
2. Place the kiln on its back.
3. Remove the screws holding the sheet metal bottom
to the kiln. Tilt the bottom
forward reach the relay
and transformer.
4. Hold the new part next to the one you are replacing,
aligned in the same direction. Remove and transfer one
wire at a time from the old part to the new one. Make
sure each connection is tight.
5. Replace push-on connectors
and wires damaged by heat from a burned terminal. If
wire connectors do not fit snugly on terminals,
gently squeeze the end of the
terminal with pliers.
6. As you move the sheet metal bottom back into place,
make sure the thermocouple wire attached to the back
of the board is away from the other wires.
7. Install the screws holding the bottom to the kiln.
Replacing the Temperature Controller
1. Unplug kiln.
2. Remove the four corner screws holding the controller
faceplate to the switch box. Carefully lift out faceplate.
3. Disconnect the wires from the back of the board. You
will find two plugs and two single wires.
The relay being replaced; the transformer is the part in the foreground.
wires away from electrical components and other wires.
9. Strip 1/2" of insulation from the ends of the thermocouple
Rio Grande warrants the Rio Kiln and controller to be free from manufacturer’s
defects for a period of one (1) year from the date of purchase. If the product fails
to work due to materials or workmanship at any time during this period, Rio
Grande will, at its option, repair or replace this product as set forth below.
The liability of Rio Grande is limited to replacement and/or repair at its factory
of a kiln that does not remain in good working order under normal operating
conditions. Rio Grande reserves the right to repair at their facility or to send
the oven to the factory for warranty repairs.
4. Connect the wires to the new board. Reinstall faceplate.
Calibrating the Controller
You can calibrate the controller to fire up to 20°F/11°C
higher or lower than the zero factory setting.
Limited warranty service may be obtained by delivering the unit within the
warranty period to RIO GRANDE; 7500 BLUEWATER RD. NW; ALBUQUERQUE,
NEW MEXICO, USA 87121-1962. Provide proof of purchase and a written
description of defect or problem.
Service may also be obtained on units no longer under warranty by returning
the unit, pre-paid, to Rio Grande with a description of the problem, and the
buyer’s name, address and telephone number. The customer will be contacted
with an estimate of the service charges before any work is performed.
Rio Grande PMC® Kiln with
Bead Door & Mandrel Holder
The Rio Grande PMC® kiln with bead door gives beadworkers an easy and efficient way to anneal flame-worked beads
while greatly reducing the cracking and splitting that can
occur when using standard kilns. Because of its small size,
the bead door allows very little cool outside air to enter
into the kiln, helping to maintain the correct temperature
for annealing beads. An attachable rack conveniently holds
bead mandrels inside the kiln.
Installing the Bead Mandrel Holder
When placing the beads inside the kiln, the mandrel holder
supports the bead mandrels.
1. Open the door. You will find two screws on the bottom
edge of the door. Loosen the screws with a 1/4" nut driver.
2. Slide the two slots in the bead mandrel holder under the
two screws in the door. Tighten the screws.
Annealing Flame-Worked Glass Beads
Glass is sensitive to breakage as it cools through the
annealing range (approximately 950°F/510°C–700°F/371°C).
The larger the piece, the slower it must cool to prevent
To safely cool flame-worked glass beads, anneal them
in your kiln using the bead door.
Programming the Kiln
Program the controller in Ramp-Hold (ProG display) for
the following two segments (see page 7 for programming
instructions). If your bead-making session will be longer
than 3 hours, program a longer hold time in segment 1.
Start the kiln. When the temperature reaches 1000°F/537°C,
it will maintain that temperature for three hours.
Annealing the Beads
1. When the kiln reaches 1000°F/537°C, it is ready for
loading with hot beads on the bead mandrels. Allow a
freshly made bead to cool slightly before placing it
into the kiln to prevent the bead from flattening on
one side when it is placed inside the kiln.
2. Open the bead door and insert the mandrels as you
complete the beads. Leave the door ajar with the end
of the bead mandrel extending outside the kiln. Please
Note: The bead door is not intended to close entirely,
there will always be a slight gap along the bottom.
3. When you have finished the batch of beads, perform a
skip segment (see page 7, item 3, under Up Arrow key.
This will end the temperature hold and begin segment 2.
The kiln will cool through the annealing range.
After the kiln shuts off, leave the beads in place. Do not
remove them until the kiln has reached room temperature.
Rate or Ramp
3 hours
7500 Bluewater Road NW • Albuquerque, NM 87121-1962 USA
800.545.6566 • FAX: 800.965.2329 • www.riogrande.com
International: 505.839.3011 • International FAX: 505.839.3016
©2007 The Bell Group, Inc. All Rights reserved. 703-117, 118.qxd 1007jd150
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