Each of these is discussed on this page. To quickly
access a specific part, click on the links.
Remember to disconnect the power to
the kiln before accessing any of its electrical parts, including elements.
The opinions I express on this page represent my own practices, presented
for discussion purposes only. If you follow any of the advice given
here, you assume responsibility for your own actions.
For advice on specific kilns, contact
An outer shell
of stainless steel
This shell holds the firebrick in place, and should last
longer than the rest of the kiln. However it is attached at the ends
usually with screw type hose clamps, and these tend to rust out, or at
least the sheetmetal screws holding them. If
you see this happening, buy some new hose clamps, cut them in half with
heavy tin snips, drill holes in the two halves near the ends for sheet
meal screws, drill new pilot holes for the screws, and attach the replacements.
Tighten when finished.
brick with peephole plugs
This firebrick holds the elements in and provides
for the kiln. The main problem with it is that chunks of the
fall off with time, particularly when elements swell after long use,
take out chunks of brick as they are removed for replacement.
once a piece has come loose it does little good to try to reattach
The parts that come loose are invariably outer pieces of the channel
support the elements. The elements, once freed, start to stretch
when red hot, and if they contact their neighbors, can arc and ruin
elements. To avoid this I use staples made from heavy
Kanthal element wire (the wire is usually available from pottery
suppliers). These staples are just U shaped bent pieces of the
wire, bent with a needle nose pliers, starting with a piece about 2
inches long. The pliers can be used to force the staple into the soft
brick of the kiln, securing the element in place. It may help to
have put them in slightly at a downward angle, so that gravity will
help hold them in place.
These crack and break from thermal stress. You
can make your own by mixing a small batch of pure clay (kaolin, ball clay,
EPK, and or fireclay) and water, with sawdust in it to give it air space.
After mixing, shape the plug by hand into a cone shape approximating the
size of the hole on the kiln. Allow for shrinkage. Dry thoroughly
and fire in your highest normal firing before use. If you use sawdust,
expect smoke as the peephole heats up.
Lid and bottom
of kiln and support.
The lid of the kiln tends to develop cracks with age.
To some extent this can be avoided by maintaining sufficient tension on
the lid, with the screw type hoseclamps used to secure the steel flange
around the outside. This flange is critical in supplying support
for the lid--if it were to become detached, catastrophic failure may result.
These hose clamps and the sheetmetal screws used to attach them can become
rusted with age, and can be replaced as necessary (instructions).
If chunks of insulating material are falling out of the lid, or any sag is detected
in it, or wide cracks are appearing, replace the lid. Even though the bottom
supports the whole kiln, it is not stressed as much as the lid, which is
opened and shut frequently, so the bottom will likely last longer than
the top. But another concern is the base which holds the whole kiln.
Sometimes this is not made of stainless steel, and if not, it can rust
out. Check for rust on your base. If necessary the kiln can be set
on regular masonry bricks or probably cement blocks, preferably with some
space to allow heat to dissipate into the air.
supply cable and circuit breaker.
These are both possible causes of frustration for the
kiln user. As the cable ages, it can build up corrosion where it
plugs in, and if the corrosion is thick enough, it can cause the plug to
arc. Since kilns are designed to draw a lot of amperage, this situation
will not necessarily trip the breaker. The closest I've come to a
fire from my business was when my plug in connector arced and started burning
the plastic housing for the receptacle. My kids noticed it and I
shut off the power and extinguished the fire before the wood wall caught.
Since then I always hard wire the kiln with screw type connectors inside
a junction box. Kilns don't need to be that portable... You may want
an electrician if you want to do this.
The circuit breaker can become a problem, if it starts
shutting off during a firing. If you have this problem from the beginning,
you probably need a bigger breaker. But breakers are matched sometimes
to wire size, so make sure your wiring can handle a bigger breaker. Also
make sure you check your elements for arcing before the expensive step
of a larger breaker. And as breakers age they can start shutting
down with lower amperage, so that may be grounds for replacing also.
Remember that you should probably not exceed the recommendations of your
kiln provider, as too large a breaker may promote dangerous arcing and
and shut off
For most of my career I didn't use a computer controller. I did use a thermocouple shut
system from Seattle Pottery (they no longer offer it), but it cost
$30 per year for thermocouples, and finally the electronics burned
the Kilnsitter (was Dawson, now Orton) with timer as the
simplest, cheapest, and most dependable
way to shut off your kiln. This means turning up your power
most of us are capable of. The kiln sitter can need new metal
which support the cones, a new porcelain tube assembly, or new contact
block in the switch. Also if the spring that makes the button
lock on gets rusty or weak, the button will get very tempermental and
not stay in... If you need advice on repairing these, email
me or talk to your supplier.
2012... I finally gave up on kilnsitters when the button got arc
welded in the on position during a firning twice this summer. I
suspected flawed materials used for the kiln contacts, but had to bite
the bullet for new kilns. Because I suspected the contacts, I
finally tried using a Bartlett controller, which is digitally
controlled and uses relays turning off and on to guide the kiln up in a
proper firing curve. Since switching, I've become a believer,
with it speeding up firings and producing predictable results. I
did have to replace one of the relays after 40 firings, covered by
warranty). Getting back to if you have a kilnsitter: The manual switches are usually either 3 position(low,
medium, or high) or infinite (no click setting from low to high).
I have had kilns with both styles. Infinite switches can sometimes be
recycled from old electric stoves. 3 position switches can handle
more amperage, so you get by with fewer of them, and are generally more
reliable than infinite switches. With either of them I turn kilns
up just three times, every two hours of the firing until they are on high.
If a switch burns out, usually there will be a post that
is wiggly, or something will rattle when it is shaken. Whatever wire
is connected to that burned post needs a new connector crimped on, to prevent
damage to the new switch. The wire itself may need replacement--if
so, contact your pottery supplier, as this is special high temperature
wire. You replace the switch by shutting off power at the breaker, removing the knob, loosening the
large nut under the knob, and moving the wires to the new switch.
It's generally easier to reattach the wires before sticking the knob on
If the button that starts the Kilnsitter going gets fussy, and refuses to stay in, here are some tips: Assuming you have remembered to put time on the knob for the kiln timer,
here are other possible fixes: You don't say how old the kiln is, but
the wire spring that makes the button stay in place while firing can get
rusty and catch on the back of the black plate that is the front of the
kiln sitter. Sometimes you can squirt some WD-40 in from the side and
that will help for a while (make sure to let it evaporate before
attempting to fire the kiln. )
The more permanent solution I've found recently involves (with
electricity to the kiln SHUT OFF at breaker) removing the 4 screws at
the corner of the face plate, and pulling the kiln sitter out far enough
that a piece of heavy nylon fishing line can be poked in from one side
to the other on the back side of the plate, below the button area. When
it comes out the other side, poke it back through to the beginning
side, making sure to loop it over the thin straight wire spring which
should be visible just below the thing that flops down to shut the kiln
off. When it comes back through, grab the two ends of the fishline and
tie them in a simple overhand knot so it's a closed loop circle, hanging
out a few inches towards the front of the kiln. Now you can push in
the button, while gently pulling on the loop, which will give the spring
some added oomph.
Elements will last until they burn out, but their efficiency
goes down with the number of firings (particularly high fires) they have
done. To check elements, turn on the kiln to high for a couple minutes.
Shut off the power, and drip a bit of water on each element. The
hissing tells you which ones are working. If they are not heating
inspect the element for an obvious gap or break. If this does not work,
run a small screwdriver or your fingernail along the whole route of the
element, checking for gaps or burnout holes. If you still haven't found
a problem, or if two elements on the same switch are not working, suspect
the switch (it's sometimes easiest to replace the switch rather than test
it.) A continuity tester can be used also to see if the element has
continuity throughout its length.
If you do find a burned out section of element, remember
to put kilnwash over it before putting in the new element. This will
prevent a hastened repeat burnout, caused by the metal residue which still
conducts some electricity.
If you want to roll
own elements or buy premade ones:
Duralite still sells the
bare Kanthal A-1 wire. Duralite in Connecticut custom rolls elements
(860-379-3113). I ordered two pounds. That will make, as I
recall, about 6 elements
for my old Crusader kiln . If you send them all the pieces of your old
element, they will size and price it for what they would make, or tell
you what how long to make yours. Then it's a question of using a rod
right length, and winding the wire on compactly. Duralite has for the
a photocopy of info on resistance per foot per gauge of wire, etc. I've
used a welded crank and steel rod (with a slot cut in the end to
hook the wire in to start. Lately I've used a variable speed drill with
rod stuck through a hole in mounted wood to stabilize it. It would help
to have one person run the drill and another to guide the wire. The
are fairly easy if you use loop ends-- tougher if they're supposed to
just tight twists.
When you're ready to put in the new
elements, clean the channel thoroughly of bits of old element and dust.
A lot of kilns use little pins in each corner to hold the element in place.
I don't like them much--most elements come sagging out of the middle flat
areas, not the corners. I just use them in problem areas (see
insulating brick repair) Cheap Electric Kiln exhaust
I once added a cheap kiln vent to my electric
I bought some flexible aluminum clothes dryer vent and attached it to
bottom peephole of my kiln with three sheetmetal screws with added
to keep from ripping through the thin metal. At the other end of
the flexible section I used standard rigid aluminum dryer vent tubing
get it out of a window. Outside I added a small fan mounted in an
A-frame of plywood (so as to protect it from rain/snow). From
I can push the vent tube closer to the fan to create more suction, or
from it for less. When I fire a bisque, I want more suction, to
the sulphur fumes. You can tell how effective the venting is by
hot the pipe is getting. It never seems to get too hot to
No longer the taste of sulphur when I fire... Do bear in
that in venting out fumes, you are also removing some air from the
which must be replaced somehow. If you are in a confined area
fuel fired appliances (gas hot water, furnace, or woodstove), the draft
created by drawing out kiln gases can also draw into the room some of
exhaust gases from these other appliances, including carbon
So you may need to run a vent hose into the kiln space to equalize
pressure. Also, using aluminum piping is better than steel
stovepipe, as the aluminum resists rusting out...