Elmer's Glass Kiln Service manual

Elmer's Glass Kiln Service manual
& Service
Thank you for choosing a Paragon Caldera kiln! We have
designed it to give you many years of reliable service.
Setting Up the Kiln . . . . . . . . . . . . . 4
Electrical Installation . . . . . . . . . . . . . . . . . . . . . . 4
Seating the Elements. . . . . . . . . . . . . . . . . . . . . . 4
Where to Locate the Kiln . . . . . . . . . . . . . . . . . . . 4
Please read this manual. It will help you gain the most
enjoyment from your Caldera kiln. It will show you how to
Basic Operation . . . . . . . . . . . . . . . 5
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
avoid damaging the kiln and will answer many questions. If
Important Guidelines . . . . . . . . . . . . . . . . . . . . . . 5
your kiln is digital, your instruction packet will include a
Loading the Kiln. . . . . . . . . . . . . . . . . . . . . . . . . . 6
separate digital controller manual. Please save both
Venting the Kiln . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Glass Fusing & Slumping . . . . . . . 7
How to Cut Glass. . . . . . . . . . . . . . . . . . . . . . . . . 7
Inspect the kiln. When you receive your kiln, check the
Fusing Compatibility of Glass . . . . . . . . . . . . . . . 8
carton for damage (crushed, holes, etc.). Check the kiln for
The Annealing Range . . . . . . . . . . . . . . . . . . . . . 8
Cleaning and Gluing the Glass . . . . . . . . . . . . . . 8
both interior and exterior damage. If the kiln is damaged,
Load Glass Into the Kiln . . . . . . . . . . . . . . . . . . . 8
you can refuse the shipment and have it returned, or accept
Firing the Glass . . . . . . . . . . . . . . . . . . . . . . . . . . 8
the shipment after having the driver note the damage on the Annealing Flame-Worked Glass Beads . . . . . . . 9
Bill of Lading. Then call Paragon at 800-876-4328 or
Enameling on Metal . . . . . . . . . . . 10
972-288-7557 (open Monday to Thursday, 7 a.m. to 5:30
How to Load the Kiln . . . . . . . . . . . . . . . . . . . . . 10
p.m. Central).
Preparation of the Copper . . . . . . . . . . . . . . . . . 10
Check the Bill of Lading to insure that you received the
correct number of packages. Note any shortages on the Bill
of Lading, and have the driver sign the copy.
If there were no signs of visible kiln damage and you discover it after the driver has left, notify the shipper
Needless worries. Tremendous stresses are generated
within the kiln. The insulating firebricks actually expand
and contract with each firing. Do not be concerned if small
cracks appear in the bricks. This is normal. These are surface cracks that close tightly when the heated brick
Decorating the Copper . . . . . . . . . . . . . . . . . . . 10
Firing Enamel. . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Ceramics . . . . . . . . . . . . . . . . . . . . 11
Pyrometric Cones . . . . . . . . . . . . . . . . . . . . . . . 11
Viewing the Cones During Firing. . . . . . . . . . . . 11
Orton Cone Chart . . . . . . . . . . . . . . . . . . . . . . . 12
Firing Overglaze . . . . . . . . . . . . . . . . . . . . . . . . 12
Firing Low Fire Greenware . . . . . . . . . . . . . . . . 12
Firing Low Fire Glaze. . . . . . . . . . . . . . . . . . . . . 13
Firing Porcelain Greenware. . . . . . . . . . . . . . . . 13
Firing Porcelain Glaze . . . . . . . . . . . . . . . . . . . . 13
Firing Stoneware Greenware or Glaze . . . . . . . 13
Glaze Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Silver & Gold Clay . . . . . . . . . . . . . 14
Drying Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Loading the Kiln. . . . . . . . . . . . . . . . . . . . . . . . . 14
Venting the Kiln . . . . . . . . . . . . . . . . . . . . . . . . . 14
Rate, Temperature and Hold . . . . . . . . . . . . . . . 14
Cooling Time . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Combining Silver Clay With Other Materials . . . 15
During firing, you will hear an intermittent, distinct clicking. In a digital kiln, this is the sound of the relay sending
power to the heating elements. In a manual kiln, it is the in- Firing Mistakes . . . . . . . . . . . . . . . 15
Silver Clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
finite control switch cycling on and off. Do not be conGlass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Ceramics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
cerned with this sound.
The Electrical data plate.
Important information about
your kiln is recorded on its
electrical data plate. Please include this information when
ordering parts or calling your
dealer or the factory about your kiln.
© 2002, by Paragon Industries, Inc. IM-211/6-02
Kiln Maintenance . . . . . . . . . . . . . 16
Trouble-Shooter. . . . . . . . . . . . . . . . . . . . . . . . . 16
Replacing the Thermocouple . . . . . . . . . . . . . . 17
Replacing a Relay or Transformer. . . . . . . . . . . 17
Replacing a Switch or Pyrometer . . . . . . . . . . . 18
Replacing the Temperature Controller . . . . . . . 18
Reseating a Bulging Element . . . . . . . . . . . . . . 18
Replacing An Element . . . . . . . . . . . . . . . . . . . . 19
Paragon Kiln Limited Warranty . . 20
Important Safety Rules
The warranty on your Paragon kiln does
not cover damage from overfiring,
regardless of the circumstances. It is the
operator’s responsibility to make sure
the kiln turns off at the proper time.
Read the Manual!
Read each page of this manual in detail
before operating your kiln. Warranty
does not cover damage caused by
failure to follow instructions.
Food or Drink Surfaces
Some decorative materials may be
unsafe and toxic when used for surfaces
that will be in contact with food or drink.
Whe n y ou m ake fo o d o r 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
g l az e o r gl ass m an u factu r er’s
instructions exactly, without any
Mastering Cone 6 Glazes, by John Hesselberth and Ron
Roy, covers food safe stoneware glazes in great detail. We
recommend this book to every potter.
An electric kiln is extremely safe to operate provided you
follow these basic safety rules:
G Unplug
kiln when not in use.
G Do not touch hot sides.
G Keep unsupervised children away.
G Before connecting power, place the kiln on
the firebrick blocks furnished with the kiln.
G Place kiln, with its firebrick blocks, on a
non-combustible surface.
G Do not install
closer than 12”
from any wall or
G The
kiln top and bottom must be in place
before firing the kiln.
G Fire only in a well ventilated, covered and
protected area.
G Keep cordset away from hot sides of kiln.
heating elements with anything.
G Disconnect kiln before servicing.
G Do not leave kiln unattended while firing.
G Wear safety glasses when cutting glass.
G Wear firing safety glasses when looking into
a hot kiln.
G Keep food away from your work area.
G Never fire tempered glass inside a kiln. It
could explode.
G Avoid firing toxic materials inside the kiln,
such as styrofoam (used as a core for silver
clay hollow beads).
Setting Up the Kiln
Electrical Installation
You must plug your kiln into a circuit that no other appliance uses while the kiln is firing. Turn off the circuit breaker
or unscrew the fuse for the circuit that your kiln will be
plugged into. Check to see if other appliances shut off too. If
that circuit powers appliances that
must remain on while the kiln is firing, plug your kiln into a different
Note: 120 volt kilns: avoid extension cords if possible. If you
must use one, never use one
smaller than 12 gauge and longer than 20 feet. Never plug it
into a ceiling outlet!
Voltage fluctuation can vary firing time from as little as
half to more than twice the average time. If the voltage is too
low, the kiln may never reach full temperature.
The receptacle must have a separate safety grounding
wire. This protects you from serious electrical shock.
Changing the cord plug will void your warranty!
The Kiln Stand
F ind a f ireproof surface for
your Caldera. We
re c omme nd a
l arge c e ra mic
shelf. You will
find four insulati ng f irebric ks
packed with your
Caldera. Place
these under the
Caution: The blocks MUST be under the kiln during firing. They help dissipate heat from under the
Seating the Elements
Shipping may dislodge the elements of your kiln. Please
perform the kitchen knife test to make sure the elements are
seated in their grooves.
Kitchen Knife Test
Caution: Always unplug kiln before touching an element with anything.
Note: Touch only a cold element—never a hot
one—with a plastic object such as a comb. Plastic
will melt on and ruin a hot element.
Press the elements
into their grooves by running a blunt kitchen
knife, plastic comb or
similar blunt object
completely around each
groove. Do this before
the first firing, because it
may not be evident to the
eye whether the coil is in
its groove. If the element
doesn’t lie flat in the bottom of its groove, you
needn’t be concerned as
long as the element fits
all the way back into each
corner and doesn’t bulge
outside the groove.
Before the kiln is fired there is no danger of breaking the
elements. After firing, however, the elements must be reseated if they bulge out of the groove. See “Reseating a
Bulging Element,” page 18.
Where to Locate the Kiln
1 Place your kiln in a well ventilated, covered and protected area such as the garage, basement, utility or
hobby room.
Note: Some people keep their kiln outside on a covered patio. This is okay so long as the kiln is not subjected to excessive humidity or rain.
2 Remove gasoline, paint, and other flammable
materials from the kiln room.
3 Provide a minimum of 12 inches clearance between
kiln and the closest wall.
4 Never allow the room temperature of your firing
room to exceed 100 - 110° F. Measure the temperature about 3 feet from the kiln. If necessary, use fans
to lower room temperature.
5 Keep the kiln away from curtains or other combustible materials.
6 Position kiln on a level, fire-proof surface. We recommend an 18” x 18” piece of sheet metal or a large
ceramic kiln shelf.
7 Keep unsupervised children away.
8 Keep the power supply cord away from the kiln case.
There is little danger of serious burn from accidental
contact if you exercise the same caution you would use with
an electric iron.
Basic Operation
Ceramic Shelves & Posts
Shelves and posts
are fireclay that has
been fired to a higher
temperature than will
be encountered in
your kiln. Ware is
placed on the shelves.
She lve s c a n be
stacked using posts.
Enameling Racks
Enameling is the art of firing glass onto metal. The metal
shapes are loaded onto 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 rack safely, use an enameling fork.
The heating element under power is dangerous. Do not
touch the element with anything! Turn the kiln switch off
before inserting the enameling fork into the firing chamber.
Glass Separator & Kiln Wash
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 shelves and
the firebrick bottom.
The main difference between glass separator
and kiln wash is that the
separator is ground more
finely to leave a smooth
back to glass pieces laid
on the shelf.
As powders, glass separator and kiln wash have an unlimited shelf life. Do not breathe the powder when mixing.
Note: CAUTION: If glass separator or kiln wash
contact a heating element, that element will burn
out in the next firing. NEVER apply glass separator
or kiln wash to the walls of the firing chamber or to
the kiln top.
Haik Brush
The haik brush is used to apply
glass separator to the kiln shelf in
a smooth, thin layer. Th e
smoother the glass separator, the
smoother the underside of the
Alumina Hydrate
Delicate silver or gold clay shapes may need extra support
during firing to prevent warping. Place these shapes in a thin
layer of alumina hydrate inside a small ceramic bisque bowl.
Do not breathe alumina hydrate.
Stilts are points embedded in a ceramic base. The points
separate enameling and glazed ceramics from the shelf and
firebrick bottom.
Wear firing safety glasses and protective gloves.
Safety Glasses
Wear clear safety glasses
when cutting or chipping glass.
Wear firing safety glasses when
looking into a hot kiln, such as
when checking the progress of
Important Guidelines
The Clicking Noise
Do not be concerned if your kiln makes a clicking sound
during firing. Digital kilns contain a relay, which sends
power to the element. The relay clicks as it cycles on and off
to maintain the correct temperature. Manual kilns use an infinite control switch that clicks as it cycles on and off.
Manual Kilns: The Infinite Control Switch
The manual kilns use an infinite control switch. A bimetallic timer inside the switch
cycles on and off to regulate
heating. The higher the switch
setting, the longer the element
stays on during each cycle. On
High, the element stays on
continuously. This is why the
clicking noise stops after the
switch is turned to High.
Check Thermocouple
The pilot light serves as the
pointer mark for the infinite control switch knob. The pyrometer
shows temperature.
You will find a rod, called the thermocouple, extending
into the firing chamber. Both manual and digital kilns use a
thermocouple. The digital controller senses temperature by
reading a small voltage from the thermocouple. If the tip of
this rod is pushed out of the firing chamber, the kiln will as-
sume that the firing chamber is
cold. On digital kilns, this will result in an over-fire. When loading
the kiln, check that the rod extends into the firing chamber by
1” or more.
Vacuum the Kiln
Clean the kiln interior before
firing glass, enameling, or ceramic glaze. (Cleaning is not
necessary when firing silver or gold clay.) Use a soft brush
nozzle on a vacuum cleaner. Vacuum the element grooves to
remove debris, which could damage the element.
Removing Hot Ware
To remove hot ware
from the kiln, turn off
the kiln. Tilt the kiln
upward about 1” by lifting the electrical box.
Ca ref ully s lide an
enameling fork under
the shelf or enameling
rack. Place the hot
shelf/rack onto a large
ceramic kiln shelf in front of the kiln. Wear thick work gloves.
Firing Log Book
Record the following information in a firing log book:
Digital: Firing speed and Hold or Ramp/Hold program
Starting time
Total firing time
Type of pieces
Firing results
As you gain experience, you will find a wealth of information in your firing records.
Low Temperature Holds (Digital Kilns)
A low temperature hold (i.e. 200° - 300°F) is more difficult to maintain than higher temperature holds (1400° 1700°F). At low temperatures, turning on the heating element affects firing temperature to a larger degree than at
high temperatures.
When holding at a low temperature, heat the kiln slowly.
Otherwise the temperature may overshoot the hold temperature before the element turns off.
Avoid Contaminating the Heating Element
Contact with silica or silica bearing compounds, such as
kiln wash, glass separator, alumina hydrate, glass, enameling
powder, and ceramic glaze, will ruin the heating element.
Note: If glaze or glass drips onto a firebrick wall, dig
out the glaze with a screwdriver. Otherwise it may
melt into a brick groove during the next firing and
ruin the element.
The Effect of Silver Residue on Glass
Firing silver clay leaves traces of silver in the firebricks.
Sometimes there is enough silver residue in the kiln to affect
glass colors. For instance, green might turn yellow.
Note: 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. See pages 7 - 9.
Loading the Kiln
Place Ware on the Kiln Bottom or
on a Protective Shelf
Ceramics can be
fired directly on the
firebrick bottom or
on a shelf. Fire glass
only on a shelf or
mold, never directly
on the brick bottom.
Types of shelves
and containers:
Fireclay Shelf
Ceramic fireclay shelves, available from Paragon, protect
the firing chamber bottom and provide a smooth surface.
Use a ceramic shelf in your kiln to fire ceramics, glass, and
china painting.
Insulating Firebrick
Insulating firebricks
are porous, light-weight,
and can be shaped to support delicate silver clay designs. Carve the firebrick
with a knife or hacksaw.
Ceramic Bowl
You can purchase an unglazed, small ceramic bisque
bowl from a ceramic supply store. The bowl will last through
many firings. Use it to hold alumina hydrate for silver clay
pieces. You can also shape hot glass by slumping it into the
Applying Glass Separator or Kiln Wash
The kiln shelf, kiln bottom, 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. When
the shelf coating begins to crack
or chip, apply a fresh coat.
When recoating a shelf, remove most of the old coating
with grit cloth (available from
Paragon). This is an abra-
Separator lasts through several glass firings. Apply new
separator when the old coat
begins to flake.
sive-coated mesh that allows residue to pass through. You
could also use coarse sandpaper. Removing the old coating
gives you a smooth surface to start with. Then recoat the
shelf using the following directions. (Both glass separator
and kiln wash will be referred to as “separator.”)
Caution: Keep separator away from the elements.
1 Mix the separator with water following the directions
on the bag. Stir.
2 Use a haik brush or a soft
paint brush to apply the
separator to the shelf.
(The haik brush is easier
to use because it lays
down a more even coating.) Each time you dip
your brush into the separator mixture, swirl the
brush around the bottom
of the container. This is because the separator settles
quickly. Use two or three thin coats changing the direction of the brush stroke 90° with each coat.
3 Dry the shelf before firing. To speed drying, place the
shelf on 3 - ½” posts inside the kiln. Heat at full rate
to 300°F/148°C and hold for 15 - 30 minutes. Then
turn off the kiln and leave the shelf inside.
4 After the separator has dried and your shelf is cool,
you can smoothen the separator further by rubbing
your hand lightly over the shelf. The smoother the
separator, the smoother the back side of the glass.
A coat of glass separator will usually last several firings.
The lower the fusing temperature, the more firings you can
get from one application of separator.
Glass Fusing &
You will probably fire mostly stained glass, but you can
also fire standard float (window) glass. Some types of float
glass devitrify (form a dull, frosty surface) when fused.
Caution: Never fire tempered glass. It could explode if heated inside a kiln.
Basic Glass Tools
Reservoir Glass Cutter uses a reservoir of oil to lubricate the cutter wheel.
Running Pliers are for cutting large pieces of glass.
Breaking Pliers are for cutting small strips.
Grozing Pliers shape the glass by chipping away the
edges. They are often used when the score line doesn’t break
clean. Note that rough edges will become smooth when fired
to fusing temperature.
How to Cut Glass
Note: IMPORTANT! Wear safety glasses when
cutting or chipping glass.
1 Lay the glass on a clean surface. Mark off the cut with
a grease pencil or felt-tip pen. A small mark on each
end of the glass will do. Lay a wooden straight edge
over the glass and line it up with the marks you just
Using Posts
Ceramic posts support ceramic fireclay shelves.
When firing glass, place 3 - ½” posts under the ceramic
shelf on the firebrick bottom. This aids air circulation
around the shelf.
You can fire two or more ceramic shelves in your Caldera.
When you load multiple shelves, use a slower firing rate.
This aids heat distribution.
Always fire glass on a shelf. Ceramics can be fired on the
brick bottom as well as on shelves.
Venting the Kiln
Some types of ware, such as
ceramics, contain impurities
that burn off during firing.
These impurities must be released from the kiln at the beginning of the firing. Otherwise
they can affect the quality of the
ware. To vent the kiln, place a ½”
post under the top.
2 Hold the straight edge firmly and score the glass
with the glass cutter. Press just hard enough so that
the scoring noise sounds steady and unbroken.
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.
3 Place the straight edge under the glass so that an
edge is lined up with the score line you just made.
Press down on the glass. It will break cleanly.
Cleaning and Gluing
the Glass
Fusing Compatibility
of Glass
When glass changes temperature, it expands and contracts. The rate at which glass changes size 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 a close enough coefficient of
expansion to fuse successfully, they’re 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 ½” 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. Include, among the sample squares, a
piece cut from the clear transparent base.
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.
Results of the Test
If you see a halo around the edges of the small glass samples, the glass is not compatible. If you see no halo, the glass
is fusing compatible.
Why did we include a sample square cut from the base
transparent glass? It 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 when 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.
The larger and thicker the glass, the slower it must pass
through its annealing range. You cannot over-anneal, so err
Grease, dirt, and fingerprints etch permanently
into the glass during firing.
Clean the 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 is coated.
Load Glass Into the Kiln
Air should circulate between the shelf
and the bottom of the
kiln, so place three or
four 1/2” posts in the
kiln. Lay the shelf
over the posts.
Firing the Glass
Firing speed varies depending on the size and thickness
of the glass project. The thicker and larger the project, the
slower you must fire it. Otherwise the glass may crack. Small
jewelry pieces, such as earrings, can usually fire at full speed.
Viewing the Glass During Firing
Watch the glass by moving the top over just enough to
where you can see inside the kiln. Look for several seconds at
a time. Wear firng safety glasses and protective gloves.
Note: When you move the top, do not slide it, or dust
particles could land on the glass. Gently lift it
Annealing Flame-Worked
Glass Beads
Glass is sensitive to breakage as it cools through the annealing range. This is approximately 950°F/510°C through
700°F/371°C. The larger the piece, the slower it must cool.
To safely cool flame-worked glass beads, anneal them in
your kiln using the optional
Bead Collar.
To look at the glass during firing, move the top slightly. Look inside
the kiln for a second or two. Wear firing safety glasses and gloves.
slightly. With every firing, be sure you are near the
kiln before the expected shut-off time.
Digital Kilns
The first time you fire a particular brand or type of glass,
program the controller for a higher temperature than the estimated fusing temperature. 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 rate and
Manual Kilns
Shut the kiln off when the glass fuses the way you want.
Make a note of the shut-off temperature shown on the pyrometer. For future firings, begin watching the glass 100° 200° below the final temperature.
Annealing the Glass
The annealing range for most glasses is between
950°/510°C and 700°F/371°C. Cool slowly through this
range. Leave the top closed, rather than vented, during cooling. This will slow the cooling enough for most projects.
Digital Kilns: If you need even slower cooling, program
a separate segment for cooling. See the kiln’s digital controller manual.
Manual Kilns: If you need even slower cooling, turn the
kiln on again for about 30 minutes while the glass anneals.
Use a medium switch setting.
Note: For safest cooling, leave the ware inside the
kiln until the kiln reaches room temperature. If you
remove the ware too soon, the sudden temperature
change can crack the piece.
Rapid Cooling of Small Pieces
To remove small pieces, such as glass jewelry, before they
have cooled completely, remove the shelf also. Leave the
pieces on the shelf until they reach room temperature. The
heat in the shelf will help prevent them from cooling too
To remove hot ware from the kiln, turn off the kiln. Tilt
the kiln upward about 1” by lifting the electrical box. Carefully slide an enameling fork under the shelf. Place the hot
shelf onto a large ceramic kiln shelf in front of the kiln. Wear
protective gloves.
1 Place the Bead Collar between the kiln and the
separate bottom. The kiln
top should be in place.
2 Digital Kilns: Program
c on t r olle r
Ramp-Hold for the following two segments.
(See the separate digital
controller manual.) If
your bead making session will be longer than three
hours, program a longer hold time in segment 1.
Fire the kiln. When it reaches 1000°F/537°C, it will maintain that temperature for three hours.
Manual Kilns: Fire the
kiln with the switch on High. At
900°F/482°C, lower the switch
setting to Med. Then keep adjusting the switch to maintain a
temperature of 1000°F/537°C.
3 At 1000°F/537°C, the kiln is
ready to receive the bead
mandrels loaded with hot
beads. Allow a freshly finished bead to cool slightly
before inserting. This is to
prevent the bead from flattening on one side when it
is placed inside the kiln.
Open the bead door. Insert the mandrels as you complete
the beads. Leave the door ajar with the end of the bead mandrel extending outside the kiln.
4 Digital Kilns: When you have finished the batch of
beads, perform a Skip Segment. This will end the
temperature hold and begin segment 2. The kiln will
slowly cool through the annealing range. Manual
Kilns: Turn the kiln off and let it cool slowly.
After the kiln shuts off, leave the beads in place. Do not remove them until the kiln has reached room temperature.
on Metal
How to Load the Kiln
1 Remove the top. Place several ½” posts on the floor
of the kiln.
2 Lay a wire enameling rack on top of the posts. If the
enameled piece is bare on the back, place the piece
directly onto the rack. If the back side of the piece is
enameled, support the piece with a stilt on top of the
3 Lower the top
onto the kiln
and fire. (See
firing instructions, page 11.)
4 To remove the
piece, turn off
the power. Tilt
the kiln upward about 1” by lifting the electrical
box. Slide in an enameling fork and remove the
enameling rack.
sure that you do not put any grease or oil onto the
copper, such as fingerprints. Clean the copper with
a 3M Scotch-Brite® pad. This pad does such a good
job that in most cases no further cleaning will be required. Additional copper cleaning products are
available in the Thompson Enamel Catalog, including Sparex No. 2.
It is best to clean the copper just before you decorate it. If
you wait too long to decorate after cleaning, the copper could
get dirty again.
Decorating the Copper
Counter Enameling
Most enameled pieces should be counter enameled on
the back side. This gives the piece a much more finished
look, it eliminates a great deal of fire-scale cleaning, and it
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.
Counter or backing enamel, a mixture that gives a mottled effect, can be used for counter enameling. Or you can
use regular enamel. Counter enamel is applied by the sifting
method described next.
5 Lower the kiln. Turn the power back on if you wish
to enamel another piece.
Preparation of the Copper
Enamels come in transparent or opaque. They can be
purchased directly from Thompson Enamel, P.O. Box 310,
Newport, Kentucky 41072. Their Lead Free Enamels come
ready to use: no enamel washing is needed.
Start with one of the many pre-shaped copper forms available, or shape and trim the copper to your own design.
1 Heat the copper on an enameling rack to about
1400°F/760°C to burn off oil or grease. Heat the
copper to 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 moves
across the copper. This indicates that the grease
has vaporized. Do not fire the copper any longer than
this point. Otherwise excess fire scale will form,
ma king the
next cleaning
step difficult.
2 After the copper
c ools , brush
any loose scale
from the copper. Use a
brush or paper
towe l, being
When firing counter enamel, underfire it so that the fire
scale 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 firing the other (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 reuse. Transparent enamels should be applied in several thin coats. Transparent
enamels can be mixed with fairly good results. If opaque
enamels are mixed, however, a grainy effect results. 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 with a spreader to a coat of
about 1/32” thick. 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.
Digital kilns: Use a Single Segment. Please see your
digital controller instruction manual.
Note: Hold time should be the length of time you
will be firing enameling pieces. In the above example, hold time is one hour.
Manual Kilns: Fire the kiln with the switch on High. At
1300°F/700°C, lower the switch setting to Med. When the
temperature reaches 1450°F/787°C, keep adjusting the
switch to maintain that temperature.
2 Lay the copper shape 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 to place the rack into
the kiln.
Note: Firing should take about three minutes and
requires undivided attention!
3 Look at your piece every 15 seconds by tilting the kiln
by the switch box about 1”.
4 When the copper piece appears a rosy red and the
enamel is smooth, turn off the power to the kiln. Lift
the kiln about 1” and remove the enameling rack
with an enameling fork. Lower the kiln. Turn the
power on if you want to make more enameling pieces.
5 Place the rack on a steel pad or ceramic shelf and let it
cool completely.
6 After counter enameling, you will need to clean the
fire scale off the front of the piece. A 3M Scotch
Brite® pad works well for this. Then clean it with
Thompson Sparex No. 2.
Pyrometric Cones
Pyrometric cones are small pyramids of clay and mineral
oxide that soften and bend when exposed to heat. They indicate when ceramic ware has fired to maturity.
Pyrometric cones come
in 1 1/8" and 2 ½” lengths.
Use the 2 ½” cones. Cones
mounted on the kiln shelf
must be slanted 8° from
vertical. They will not bend
ac c u r at e ly if t h e y ar e
slanted to the wrong angle.
S e lf - su ppor t in g lar ge
cones have the correct slant
built into the base. Stand ar d c on e s mu st b e
mounted in a clay or wire
A self-supporting cone fired to maturity. Do not be concerned if the tip is
slightly higher or lower than shown.
The chart on page 12
shows the temperatures of
pyrometric cones.
Digital Kilns: Program your controller to the
cone recommended for the
ceramic ware that you are
firing. Use Cone-Fire
A “puddled” over-fired cone.
Manual Kilns: For
small ceramic pieces, such
as figurines, fire at a rate of
about 400°F/222°C per
hour. Ceramic jewelry can
be fired even faster. Fire to
the temperature shown in An under-fired cone.
the 108°F column of the
Temperature Equivalents chart for the cone number you are
firing. (See next page.) Before deciding on the firing speed
of important pieces, test fire samples.
Viewing the Cones
During Firing
Move the kiln top
½” - 1” to see the cone
on the shelf. (Be sure
to wear firing safety
glasses and heat-resistant gloves.) Turn
the kiln off when the
c on e b e n d s t o 6
o’ c loc k . ( S e e t op
photo above.)
°F Temperature Equivalents For Orton
Self-Supporting Pyrometric Cones
Heated at:
Self-Supporting Cones
27° F
108° F
270° F
Per Hour* Per Hour* Per Hour*
Light Blue
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
05 1/2
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
Dark Red
5 1/2
*Rate of temperature increase during last 90 - 120
minutes of firing. Tables by courtesy of the Edward
Orton, Jr. Ceramic Foundation.
Firing Overglaze
Overglaze is decoration applied over fired glaze or polished porcelain bisque. Overglazes include china paints,
gold, and luster, which fire from 022 to 014.
Load overglazed ware the same way you would load ceramic glaze. Use stilts and make sure ware is not touching
other ware. Ware must be completely dry before firing.
China paints will crack or peel if applied heavily. Apply
several light coats instead, firing between each, until you get
the shade you want. Not all china paint colors reach maximum color saturation at the same temperature even when
fired on the same ware. So you must know which colors you
should fire first at higher temperatures to prevent burning
out the original 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 overglaze manufacturer’s literature for the
cone to use with each color and type of ware.
Vent the kiln during the first hour of firing by placing a ½”
post under the kiln top. Allow kiln to cool to room temperature before opening the kiln.
Firing Low Fire Greenware
Low-fire greenware has a firing range from cone 06 to 02.
The greenware must be bone dry before firing. Otherwise, it
will crack or even explode in the kiln. Check for dryness by
touching to cheek or inside of wrist. Moist ware will be cold.
Low-fire greenware may be stacked so that it touches
each other. It can be loaded without stilts. Load pieces directly on the firebrick bottom.
Ware should be fired in the position in which it will be
used when finished, except for large pieces with flat, vertical
surfaces such as wall plaques and clocks. These should be
fired flat to prevent warping. Pieces to be used together
should be fired in place, such as a box with its lid, to ensure a
good fit.
Low-fire greenware firing is simple. Just be certain the
greenware is fired to the pyrometric cone recommended by
the clay supplier. If the greenware is not fired hot enough,
the piece will absorb moisture after it has been glaze-fired
causing the glazed surface to crack. This is called “crazing,”
and is most often due to underfired greenware. To help
eliminate crazing, fire greenware at least one cone hotter
than glaze, and even hotter if glaze can still be applied easily
to the hard bisque. While glaze may be applied to greenware
and fired once, separate firings produce better quality, so we
do not recommend single firing of greenware and glaze.
Vent the kiln during the first hour of firing by placing a ½”
post under the top. Allow kiln to cool to room temperature
before opening.
Firing Low Fire Glaze
Wet kiln wash would be too difficult to remove. Pieces likely
to warp in firing should be supported by rolls of porcelain
clay shaped to fit the objects at points of strain. Apply dry silica or high fire kiln wash to the points of contact to prevent
sticking. Before firing, the support rolls must also be dry.
Clean the firing chamber before each glaze firing. Wipe
surfaces with a clean, damp cloth or vacuum with the soft
brush nozzle attachment of a vacuum cleaner.
Since a kiln is slightly hotter near its sidewalls, the side of
the ware next to the walls will tend to shrink more than the
opposite side. This can be used to your advantage with porcelain figurines that tend to warp during firing. Turn the inclined side of the figure away from the elements so the heat
can help hold the piece straight.
Low fire glazed ware must not touch each other, the floor,
or a shelf in your kiln during firing. If this happens they will
permanently bond together by melted glaze and be ruined.
Use stilts to support low-fire glazed ware during firing.
The shelf tops and kiln floor MUST be kiln washed with all
purpose, high fire kiln wash for protection from glaze drops.
Glazed pieces must be thoroughly dry before firing and
should not be fired with greenware unless both mature at the
same cone. Check to make sure that first, no two pieces of
glazed ware are touching each other, the kiln walls, the floor
or the shelf; and second, that the underside of the kiln shelf
is clean before you place it over glazed pieces. Any dust falling on your ware will cause pinholes.
Make sure cones on the shelf are clearly visible. At porcelain temperatures, they are difficult to see. Vent the kiln during the first hour of firing by placing a ½” post under the top.
Wait until kiln cools to room temperature before opening it.
Firing Porcelain Glaze
You can prevent glazed pieces from sticking to the shelf
or kiln bottom by “dry footing.” To “dry foot” a piece, remove all glaze from the portion of the piece that will rest on
the shelf. Using a wet sponge or a piece of grit cloth, clean off
the glaze from the bottom of the ware and slightly above the
base so that it will not run down and touch the base. Dry footing should not be used for low-fire glazed pieces that will be
placed in water while used or cleaned.
Porcelain pieces that have been fired together in the
greenware firing cannot be fired together in the glaze firing.
Both pieces must be “dry footed.” Since shrinkage has already occurred in the greenware firing, the pieces will still fit
even when fired separately in the porcelain glaze firing. Stilts
must not be used to support porcelain. Porcelain softens during firing, and stilts would embed into porcelain. Make sure
your shelves and kiln bottom have a good coat of kiln wash
before firing porcelain.
During the first hour of firing, vent the kiln by placing a
½” post under the top. Wait until the kiln has cooled to room
temperature before opening the kiln.
If a piece of ware had to be supported in the porcelain
bisque fire, it will stand alone in the glaze fire. The lower
temperature will prevent sagging.
Remove the stilts from the ware after firing by breaking
the thin film of glaze holding them. Handle with caution; the
glaze is sharp where the points touch. Remove the sharp stilt
edges by rubbing with a stilt stone or electric grinder.
Vent the kiln during the first hour of firing by placing a ½”
post under the top. Wait until kiln cools to room temperature
before opening the kiln.
Firing Porcelain Greenware
Loading porcelain greenware is similar to loading glazed
ware, since both will stick to anything during firing.
Greenware must be completely dry before firing, including
the joints on pieces that are attached. If a piece is broken before firing, mend the break but do not attempt to fire it until
the mend is also bone dry. Damp greenware or damp
mended areas will form bumps on the fired ware.
Stilts CANNOT be used to support porcelain greenware.
They would embed into the porcelain. To protect porcelain
from sticking to the shelves or kiln floor, apply a coat of high
fire kiln wash to the shelf tops and brick bottom. Then place
your ware directly on the kiln washed surfaces.
Note: Never use ceramic kiln wash in a kiln that will
ever be fired to porcelain temperatures, as the ceramic kiln wash will harden at high temperatures
and be impossible to remove.
Pieces of ware that are to be used together must be fired
together, such as a box and its lid. Dry all purpose, high fire
kiln wash can be used to separate these pieces during firing.
Firing Stoneware
Greenware or Glaze
Stoneware is made from vitrifiable clays with a firing
range of cones 2 - 10. It has a wide range of colors and textures and is popular with the potter because of its excellent
throwing qualities. Usually the greenware is fired below maturity, and on the second firing, the clay and glaze mature together to form an integrated body-glaze surface.
Like porcelain greenware, stoneware is placed directly
upon the kiln-washed shelves in the greenware firing.
Glazed stoneware must not touch any other ware and
must be dry footed before you place it on a kiln-washed shelf
or kiln bottom. Never stilt stoneware during either firing.
Glaze Testing
Make batches of uniform clay shapes, such as circles or
triangles. Each shape should have a smooth section and textured section. Glaze the test shapes. Prop them up vertically
inside a dish and fire them. Keep detailed records in a glaze
notebook. Save the test samples. They will be valuable later.
Silver & Gold Clay
With silver clay, it is possible to shape intricate, free-form
silver jewelry in minutes—even as a beginner. (The clay is
also available in gold; for simplicity we will refer to both metals as “silver clay.”) At the time of printing, the silver clay
brands available were Art Clay Silver and Precious Metal
Silver clay looks and feels like modeling clay. It is formed
with simple tools such as a tooth pick, small knife, and razor
blade. Its surface is pliable and accepts impressions from
objects such as leaves, coins, and coarse fabrics. After the silver clay is formed, it is fired in a kiln. The recommended
temperature and hold time are included with the silver clay.
Forming and firing silver clay is simple. There is nothing
mysterious about making silver clay jewelry. The clay 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 real silver. Since the
binder disappears, there is a certain amount of shrinkage
during firing. Shrinkage varies depending on the type of silver clay you use.
Drying Time
Small, thin silver clay pieces can be placed into the kiln
while still moist, and fired. Thicker pieces need time to dry.
Otherwise they may warp during firing.
To be on the safe side, give the silver clay 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.
Loading the Kiln
Silver clay pieces that have a flat side can be placed inside
the kiln directly onto a shelf. Use a soft ceramic fiber shelf. It
cushions the clay silver.
Silver clay pieces can be close together, but they must not
Place the soft ceramic fiber shelf directly onto the firing
chamber bottom.
Do not coat the ceramic
fiber shelf with kiln
wash or glass separator.
If the silver clay shape needs deeper support, pour the
alumina hydrate into an unglazed ceramic bisque bowl.
These are available at ceramic supply stores.
Place the ceramic bowl directly onto the kiln bottom.
NEVER use a glazed bowl to hold the alumina hydrate. If
the glaze runs, it will embed into the firebrick bottom.
Caution: Avoid breathing alumina hydrate dust.
Alumina hydrate can destroy the heating element on
contact. If it spills onto the firing chamber, remove
with a vacuum cleaner.
Venting the Kiln
Silver clay by itself needs no venting. Load the kiln, lower
the lid, and leave it closed until the clay silver is ready to remove.
The kiln needs venting if
you fire ceramics with the
clay silver, or if you make
hollow objects that contain
a core of organic materials.
In those cases, vent the lid
during the first hour of firing by placing a ½” post under the kiln top.
Paper maché and paper clay are good core materials. Do
not use wax or styrofoam as a core. They emit harmful
Rate, Temperature
and Hold
Each brand of silver clay fires to a specific temperature
and hold time. This information is available from your silver
clay supplier.
Note: Hold time is the lenth of time that the recommended temperature is maintained in the kiln. Do
not fire longer than the recommended hold, or the
silver will begin to overfire.
Besides selecting a temperature and hold time on your
kiln’s digital controller, you will also need a firing rate. (See
the separate digital controller instruction booklet.) Select a
Full Power rate if you are firing silver clay alone. If you fire
glass or ceramics with the silver clay, select a rate best suited
for the glass or ceramics.
You can also place the
silver clay on a piece of
ceramic fiber batting.
Alumina Hydrate
Rounded, hollow, or
other delicate shapes may
need support to prevent
collapsing. You can lay
these pieces onto a mound
of alumina hydrate.
If the piece needs only shallow support of ¼” depth or
less, pour the alumina hydrate onto a ceramic fireclay shelf.
Support the fireclay shelf on 3 - ½” posts to aid heat flow under the shelf.
Place the clay silver on a ceramic fiber shelf, which has a soft surface.
Note: Do not place silver clay 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 inserting the silver clay.
After the kiln begins firing, leave the top closed. Do not
lift the top until it is time to remove the clay. Visual inspection of the clay during firing is unnecessary.
If you are firing glass with the silver clay, on the other
hand, you will need
to check the fusing
progress of the glass
by moving the kiln
top ½” or more and
l o o k ing inside.
Look for just a second or two. As you
gain experience, you
will be able to program the correct
temperature for the silver clay and glass combination, eliminating the need to visually check the glass.
Manual Kilns: Select the type of silver clay that has the
shortest hold time. You will need to adjust the switch during
hold to correct the temperature as it drifts.
Cooling Time
After the clay silver has fired to completion, you can lift
the top an inch to speed cooling. If you are firing stones,
glass, or other materials with the silver clay, it will be safer to
allow the kiln to cool slowly with top down. Remove the piece
when the kiln reaches room temperature.
Combining Silver Clay
With Other Materials
There are two ways to fire silver clay with other materials
such as glass:
Fire the silver clay first by itself. After you have cleaned
and polished the silver clay, fire it a second time with
Fire the silver clay and other materials, such as a stone,
together in a single firing.
Glass is often fired with the silver clay in a single firing.
Many types of glass, however, will melt at silver clay temperatures. If you are going to combine glass and silver clay in a
single firing, test a small sample of the glass. To do this, fire
the glass during a silver clay firing, keeping the glass separate from the silver clay piece. (This way you won’t ruin the
silver clay piece.)
Place the pieces on a ceramic fireclay shelf. You must coat
the shelf with glass separator, or otherwise the glass sample
with embed into the shelf.
If the glass sample survives the firing, you can fire that
type of glass with silver clay 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.
Firing Mistakes
Silver Clay
Cracks that appear in fired silver clay may be due to too much
water in the silver clay before it was fired. Another cause is
careless handling of a dried piece before firing. To repair, fill
the crack with silver clay and fire again.
Brittle Silver clay will not reach full strength if underfired.
You may be able to save the piece by firing again to the correct
temperature and hold.
Too Much Shrinkage When silver clay is overfired, it
shrinks too much and loses detail. You may need to replace the
thermocouple on the digital kiln if the temperature is
Glass Cracking is caused by heating or cooling too fast or
fusing incompatible glass. Not enough glass separator on the
shelf can also cause glass cracking.
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. This critical range
applies to both heating and cooling.
The second critical temperature range is annealing,
which is the cooling range of 950° - 750°F 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
tilt 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 kiln. 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 they won’t be tempted to open the
kiln while it is still hot.
After each firing, examine the shelf. Recoat if the kiln
wash is chipped. When glass sticks to a bare section of shelf,
the glass will crack.
Glass Bubbles are often caused by heating the kiln too fast.
Air, grease or dirt trapped between layers of glass can cause
bubbles. Other causes are uneven glass volume, and moisture
or air trapped 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 for 30 minutes before placing glass on it.
One way to eliminate bubbles is to hold the temperature
at 100°F below fusing temperature for 20 minutes. This
gives the shelf time to heat up to match the temperature of
the glass.
Glass Separator Sticks To Glass when fired too hot. Instead of firing to a full fuse temperature, try firing 50°F cooler
and holding at that temperature for twenty minutes.
Breaking in Overglaze Firing can be caused by 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. Standing plates on edge or using a plate holder gives good heat circulation and will help in
preventing plate breakage.
Peeling China Paint can be caused by applying the paint
too heavily.
Kiln Maintenance
Kiln Does Not Turn On, Display is Blank
Make sure the circuit breaker
is in the “on” position.
Digital Kilns: If the breaker
is on, check the kiln’s fuse. It
is located on the kiln’s switch
box. 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 ohmeter reads
less than one ohm (digital
meter) or reads 0 ohms (analog meter), the fuse is bad.
Replacement fuse:
Loss of Color in China Paints is usually a result of
overfiring, or thinning your paint with too much medium when
Faded Colors in Overglaze Decals is the result of either underfiring or overfiring. If pinks and reds are drab, refire
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
underfired, refire to proper firing cone. If decal was overfired,
the design may be repainted in china paints and refired.
Weakening of Luster Colors can be due to overfiring.
AGC ½ A 250V AC
Powdering of Luster Colors can be caused by too heavy
an application.
Note: If you do not have an ohmmeter, visually inspect the fuse. You will see a thin strand of unbroken wire in a good fuse. The wire usually appears
broken in a burned fuse, like the filament in a light
Warped Ware can be caused by distorting upon removal of
the piece from the mold, firing too close to the elements, or firing a piece in an unnatural position. To prevent porcelain cups
or bowls from warping when firing the greenware, edge the top
of a cup with pinches of dry silica or DRY all purpose, high fire
kiln wash and place a second cup on top of the first cup, lip to
lip, with handles going in opposite directions. Porcelain
greenware plates may require firing in plate saggers to prevent
warping during firing.
Circuit Breaker Trips
If the circuit breaker trips after the kiln has fired for
awhile, make sure no other appliances are operating on
the same circuit as the kiln. The breaker may need replacing.
If the circuit breaker trips
immediately after the kiln
is turned on, the kiln may
have a short circuit. Unplug the kiln. Open the
kiln switch box and look
for a loose wire touching
the case.
Crazing is usually caused by underfired bisque. Bisque
should be fired to the highest temperature at which it will still
take glaze. Crazed ware may be refired to the proper cone.
CAUTION: China paints and other overglazes will burn off
when fired to 06.
Crazing Immediately on Removing from the kiln can
be caused by not firing the ware hot enough. Refire to the
proper cone. Crazing in spots can be caused by not having
mixed the glaze thoroughly before using.
Temperature is
Make sure the thermocouple
is pushed 1” or more into the
firing chamber.
If the temperature is inaccurate even though the thermocouple extends into the firing
chamber at least 1”, replace
the thermocouple.
Bumps in porcelain are usually caused by wet greenware and
overfired porcelain bisque.
Lack of Translucency in porcelain can be caused by the
ware being poured too thick and underfired.
Cracks in porcelain bisque are often the result of a strain on
the greenware while drying. Do not force-dry greenware.
Cracks may be mended with one of the new “magic menders”
available from your supplier.
Replacing the
1 UNPLUG the kiln.
2 Remove the screws on the
sides of the switch box that
hold it to the kiln. Gently
lift the box away from the
3 Remove the two screws securing the thermocouple ceramic
block. Pull thermocouple from
its firebrick hole. Loosen the
screws holding the thermocouple to the ceramic block.
4 Slide the new thermocouple
into the thermocouple hole.
The thermocouple should
protrude into the firing
chamber 1” or more. To adjus t the thermocou ple
length, change the gap between the thermocouple and
the ceramic block. Then securely tighten the 4 screws
in the ceramic block.
5 Fasten the ceramic block to
the heat shield with the two
screws removed in step 3.
Kilns: Remove the 2 thermocouple wires from the
back of the pyrometer.
8 Strip ½” of insulation from the ends of the new thermocouple wires. Be sure the wire ends are separated
where the insulation has been stripped. If bare ends
touch, the thermocouple will not work properly.
9 Attach the wires to the back of the controller or
pyrometer. One wire is yellow, the other red. Make
sure the wires connect to the correct terminals,
which are color coded. Reinstall the controller or
pyrometer to the switch box.
10 Position the thermocouple wires so they are away
from the hot sides of the kiln case and other electrical
wires. (Placing thermocouple wires next to or looped
around other wires could cause erratic controller
11 Check that no wires touch the kiln case or element
connectors. Wires touching element connectors
or kiln case will burn. Reinstall switch box.
Replacing a Relay
Or Transformer
(Digital Kilns Only)
1 UNPLUG kiln.
2 Remove the screws on the sides of the switch box that
hold it to the kiln. Gently lift the box away from the
3 The transformer and relay
are bolted to the inside of
the switch box. 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.
6 Digital Kilns: Remove the controller faceplate from
the front of the switch box. Manual Kilns: Remove
the pyrometer from the front of the switch box.
7 Digital Kilns: Remove the 2 thermocouple wires attached to the back of the controller. They are held in
place by button or lever type connectors. To remove
the wires, lift the levers (or press down on the connector buttons) and pull the wires out. Manual
4 Replace push-on connectors
and wires damaged by heat.
If wire connectors do not fit
snugly on terminals, gently
squeeze the end of the terminal with pliers.
5 Remove the old part from
switch box. Install the replacement.
Note: If you are replacing the transformer, examine
the new one to make sure the primary is properly
wired for your kiln’s voltage. (See the kiln’s wiring
6 Check to see that wires are not touching kiln case or
the element connectors. Wires touching element
connectors or the kiln case will burn out. Move
switch box into place and reinstall switch box screws.
Replacing a Switch
Or Pyrometer
(Manual Kilns Only)
1 UNPLUG kiln.
2 Remove the screws on
the sides of the switch
box that hold it to the
kiln. Gently lift the box away from the kiln.
3 Switch: Pull off the switch knob with fingertips.
Hold the new switch at the side of the switch box in
the same position as the
defective switch, aligned in
the same direction. Remove and transfer one wire
at a time from the old
switch to the new one.
Make sure each connection is tight. Replace
push-on connectors and wires damaged by heat. If
wire connectors do not fit snugly on terminals,
gently squeeze the end of the terminal with pliers.
(See photo, page 17.)
Remove the single nut from the front of the defective switch. Remove the switch and put the new one
in place making sure it is right side up. Reinstall the
shaft nut checking to be sure it is not backwards.
Tighten the switch so that it will not turn during operation.
Pyrometer: Remove the thermocouple wires from
the pyrometer and the four nuts holding the pyrometer in place. Install the new pyrometer. The red
wire attaches to the negative
terminal, the yellow to the positive.
3 Check to see that wires are not
touching kiln case or the eleme nt c onnectors. Wires
touching element connectors
or the kiln case will burn out.
Move switch box into place and reinstall switch box
Replacing the
Temperature Controller
(Digital Kilns Only)
1 UNPLUG kiln.
2 Remove the 4 corner screws holding the controller
faceplate to the switch box. Carefully lift out faceplate.
3 Disconnect all the wires from the back of the board.
You will find two plugs and two single wires.
4 Connect the wires to the new board. Reinstall faceplate.
Reseating a
Bulging Element
To push a bulging element back into the groove, first heat
the element. Once an element has been fired, it becomes
brittle and will break if it is bent while cold. Follow this procedure to heat the element:
1 UNPLUG the kiln. Use a small propane torch
(available at a building supply store) to heat the
bulging element. Stop heating when the element
glows dull red.
2 With a pair of long nosed pliers, shrink the bulging
portion of the element by pressing the individual
turns in the coils together slightly. Take a little from
each turn so that no two turns will be pressed tightly
enough to touch.
3 As the element shrinks,
work it back toward the
groove and into place.
Work rapidly, and at the
first sign of stiffness in the
coils, stop bending and reheat the element. The elements do not have to be red
to be bent safely, as the
stiffening can be felt
through the pliers.
These two photos show how
to shorten and lengthen an element. Use needle nose pliers
to shorten; snap-ring pliers to
4 To lengthen the element to
fit into the corners, reverse
the above procedure and
expand the distance bet we e n c oils b y u sin g
snap-ring pliers. Use caution, as your warranty covers elements that fail only in service under normal
use and not from being broken while cold.
5 When you have the coils positioned above the
dropped recess in the grooves, press the element
into the groove with a blunt kitchen knife.
Note: Do not use a plastic object, such as a comb, to
press the hot element into the groove. Melted plastic ruins elements.
Replacing An Element
Paragon replacement elements are stretched to the
proper length for the Caldera at the factory. However, a little
stretching or compressing may be necessary for a perfect fit.
It is safe to bend and stretch new elements before they have
been fired, but once fired and allowed to cool, elements become brittle and will break if bent.
1 UNPLUG the kiln and allow to cool to room temperature. Remove the top. Lift the kiln off the bottom
and place the kiln on a table.
2 Remove the screws on
the sides of the switch
box that hold it to the
kiln. Gently lift the box
away from the kiln.
3 Remove the screws in
the element connectors
that hold the element
lead wires to the element you are replacing.
4 On the same connectors, loosen the screws
that hold the element Hold the element connector with
and throw old connec- locking pliers when removing and intors away. Always use stalling the connector.
the new connectors
furnished with the new element.
5 Remove and save the porcelain insulators that were
behind element connectors.
6 Remove the old element carefully to prevent breaking
the lip of the element grooves.
If the old element burned out due to contact with foreign
materials, there will probably be a melted, glazed spot in the
element groove. Glazed spots left in the grooves may ruin the
new element, so dig out any of these spots. The small hole
left in the groove will not affect the new element. Small
pieces of firebrick in the grooves should be removed with a
vacuum cleaner.
7 Thread the new element into the upper
element hole.
8 The element must
fit all the way into the
back of each corner.
Making a bend in the Inserting the new element into the fireelement at the cor- brick hole.
ner will help hold the
element in place during firing. Start by pushing the
element into the first corner. Hold the element
against the back of the corner with a screwdriver or
pliers. Then gently pull the free end of the element
toward you. The element will bend where
sc r e wd r iv e r
presses against it.
Note: Remember, if
you do not push the element fully to the
back side of each corner, the element will
not stay in the grooves
when fired!
Bending the element at the corner.
Use a screwdriver or pliers to hold the
element while you pull it.
9 If the element is
sligh t ly t oo lon g
when you reach the
se c on d f ir e b r ic k
hole, you can compress the element
with long-nose pliers. If the element is
several inches too
lon g, it was n ot If the element is too long, squeeze the
pushed all the way to coils together slightly.
the back of each corner and should be rethreaded. If the element is too
short to reach the firebrick hole, unthread some of
the element. Gently stretch it in your hands. Avoid
stretching only a short portion of the element. It is
better to distribute the stretch over a longer section.
10 Press element down into the lower part of the groove
with a plastic comb or wooden tongue depressor.
11 Reinstall the porcelain insulators. Push them flush
against the heat shield. They protect the element
from contact with the stainless steel kiln case and
heat shield, so they must not work their way out after
the element connector is tightened into place.
12 Sandpaper the eyelet of the element lead wires until
bright and clean of all oxidation. (Install new lead
wires if insulation on old ones is brittle.) Use the
brass screw to connect lead wire eyelets to the new element connectors. Before tightening screw, adjust
eyelet to where it will be tilted away from heat shield
when connector is attached to element. Then hold
connector with locking pliers and tighten brass screw
securely with a 1 4” nutdriver.
13 Pull end of element tight and install new element
connectors snugly against porcelain insulators to
prevent insulators from slipping away from brick
Use stainless screw in the element connector to hold the
element. (The brass screw holds the lead wire eyelet.) Hold
connector with locking pliers as you tighten the screw with
the 1 4” nutdriver. Tighten the screw to 30 inch pounds
(about 1 1 4 turns past the point of firm resistance).
14 Cut off twisted
end of element
even with side of
element c onnectors. Leaving
the excess element sticking
out past element
connector could
ruin your new element! (The el-
ement could short against something in the switch
15 As you move the switch box back into place, check
to see that no wire touches an element connector.
Wires must also not touch kiln’s case inside the
switch box. Wires will burn if they touch the case or
element connectors. Reinstall screws in switch box
and tighten.
Tighten the element connectors according
to step #14. Then cut off the element ends.
Paragon Kiln
Limited Warranty
Paragon kilns are warranted to the original purchaser by
Paragon Industries, Inc. (herein “Paragon”), subject to the
listed exclusions below, to be free of defects in workmanship
for the period specified below. The warranty period begins
from date of shipment from the Paragon factory unless date
of original purchase from an authorized Paragon distributor
or dealer can be established.
Warranty Period:
Caldera series kilns rated to 2350°F: 1 year
This warranty period applies unless otherwise agreed to
in writing.
This warranty excludes: 1) Kilns damaged by overfiring
(exceeding the melting temperature of the material being
fired) regardless of cause of overfiring; 2) Ware, tools, kiln
furniture, or anything inside damaged by overfire; 3) Kilns
allowed to exceed the maximum temperature shown on
kiln’s nameplate, regardless of cause; 4) Kilns subjected to
abuse, neglect, freight damage or improper storage; 5) Kilns
used for either reduction or salt firing, 6) Kilns damaged by
improper electrical installation; 7) Kilns used for purposes
other than firing ceramics, glass, heat treating, or the purpose for which it was intended; 8) Element burnout caused
by contact with foreign materials; 9) The patented Dawson
Kiln Sitter and/or Limit Timer manufactured by W.P.
Dawson, Inc., 399 Thor Place, Brea, California 92621.
Paragon Industries, Inc., will repair or replace any parts
that become defective under normal and proper use during
the specified period for the kiln purchased, providing the
kiln has not been subjected to misuse or the listed exclusions. Paragon will furnish and install replacement parts at
the factory with transportation costs to and from the factory
paid by the owner; or upon receipt of defective parts at the
factory, and after factory examination of the defect, Paragon
will furnish replacement parts, complete with installation
instructions, shipped postpaid to owner. The warranty on
the repaired and/or replaced parts will be limited to the unexpired term of the original warranty.
Any claim for adjustment under this warranty must include name and address of dealer from whom kiln was originally purchased. Repair or replacement of any defective parts
shall fulfill all obligations of Paragon. No other obligations or
liabilities are assumed in connection with Paragon kilns nor
does Paragon Industries, Inc. authorize its distributors or
dealers to assume any other obligations or liabilities on its
This agreement is made in the State of Texas and its validity, construction, and all rights under it will be governed
by the laws of the State of Texas. This warranty gives you
specific legal rights, and you may also have other rights,
which vary from state to state.
2011 South Town East Blvd.
Mesquite,Texas 75149-1122
972/288-7557 / Toll Free: 800-876-4328
Fax: 972-222-0646 / Toll Free Fax: 888-222-6450
[email protected] / www.paragonweb.com
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