First, the “n” really is silent, at least
according to the American Heritage
Dictionary. There are kilns as big as your
house, used for cooking everything from
grain to stone, but we don't need to concern
ourselves with those. Even in the
sub-sub-category of benchtop electric
kilns there are plenty of questions. Let's
take a look at a few:
What are my options?
In descending order: programmable,
pyrometer, and unregulated. The first
option includes a device that monitors
the power and turns it on and off as
needed to maintain a specific heat. The
second includes a device that measures
the kiln's temperature and
displays the temperature inside
the kiln. You'll need to regulate
the heat manually, but you can
read the temperature and know
what changes to make. In the
last category are kilns without a
temperature indicator. For these
you use a separate pyrometer, temperature
indicator pellets, or instinct.
Does the choice of kiln have anything
to do with the type of PMC I'm using?
Sort of. A programmable kiln will handle
any version with ease and confidence.
If you are controlling the heat
manually (option #2 above), the shorter
firing times and various temperature
goals of the newer versions of
PMC make the process a lot easier.
You could think of it like an archery target. Original PMC must be held at
1650°F for two hours. That's a small
circle. PMC+ can be fired at temperatures
ranging from 1470° to 1650°F and
needs to soak for as little as 10 minutes.
That makes it a bigger target.
PMC3 can be fired at temps as low as
1110°F and is safe up to 1650°F.
What's the advantage of a
A programmable kiln can read the temperature
inside the kiln and adjust the
power to maintain a consistent temperature.
They can also be set to turn off at
a particular time. The primary advantage
of these features is convenience, since a
programmable kiln will not require the
same constant attention required by a
manual or unregulated kiln. But it offers
other advantages too, including more
consistent results. Because the kiln
maintains an even temperature, you can
be sure that the fusing process has been
optimal. In addition, some buildings
experience electrical surges or spikes,
so even a carefully watched manual kiln
can jump to a high temperature unexpectedly
and ruin a batch of work. The
programmable kiln operates on heat,
rather than current, so whether the heat
rises gradually or on a spike, when the
temperature gets to the desired setting,
the power is immediately shut off.
Can I use the same kiln for
pottery and PMC?
Ceramic kilns reach high enough temperatures
to fire PMC, but most ceramic kilns
are large enough that they have hot and
cool zones. This variance is potentially
too large to guarantee a successful PMC
firing. That is, when the pyrometer reads
1650°F, some areas of the kiln chamber
might be 1750°F, a temperature that will
melt PMC. That said, the newer, more versatile
versions of PMC are easier targets to
hit, so ceramic kilns become more viable.
The PMC will do no damage to the kiln.
Can I use a caster's burnout oven
When PMC was first released, we recommended
the Neycraft burnout oven as
the most appropriate kiln available at
the time. If you already have a burnout
oven, you can use it for PMC. Again,
there is no danger or maintenance issue
in using the same kiln for both purposes.
However, if you don't already have a
burnout oven, a programmable kiln is
only a little more money, and is well
worth the investment.
Is one brand better than another?
I don't think so. Choose the features you
want and can afford. Kilns with similar
features are probably of equal merit, so
make your choice based on the kiln's
size and cost. The big difference you'll
find is that some kilns are made of brick
and others use a lightweight refractory
foam. Aside from the weight, which only
matters if you'll be moving your kiln
around, the brick units take longer to
How dangerous are kilns?
Kilns are probably safer than toasters –
first, because they are enclosed and second,
because we don't take them for
granted. Locate the kiln so it has at least
8 inches clearance all around and set a
couple bricks or ceramic tiles in front to
catch anything that might roll out. If
there are children or pets in the area,
take appropriate precautions.
How about maintenance and repair?
Kilns are really quite simple and consist
of a heat-resistant box, a coil of metal that
warms when electricity is passed through
it, and a switch, in some cases a switch
linked to a temperature reading device. If
the "box" breaks, it can be mended with
cement from a pottery supply. If the coil
breaks (and this is uncommon) you'll need
to contact the manufacturer for a replacement.
The switch is probably the most fragile part of a kiln. In a simple unit you
might be able to buy a replacement at the
local hardware store. Replacement programmable
devices can be purchased
from the manufacturer and wired into a
kiln pretty easily.
Can I work in PMC if I don't
have a kiln?
Yes. One of the reasons the Mitsubishi
scientists developed the ultra-dense
PMC3 was to create a silver clay that
would fuse at low temperatures in a
short time. This opens the door to two
unique opportunities – torch firing and
Sterno furnaces. With a little practice
anyone can use a jeweler’s torch to sinter
Other options include kilns you rig up
from other heat sources, such as a jeweler’s
If I can torch fire PMC,
why should I buy a kiln?
Owning a kiln has changed my life. Okay,
that's a bit overblown, but they are great
things to have. I have used my PMC kiln
to sinter all kinds of PMC, to fuse enamel,
and to anneal metal. They can also be
used to anneal glass, burnout flasks for
casting, slump glass, and make dichroic
glass. And if by some chance you find you
don't use your kiln, they are easily resalable.
The Guild web site offers a new feature
called "Buy, Sell, Swap" where I
often see people requesting used kilns.
How much do kilns cost?
The cheapest kiln I know of is the
Ultralite, which sells for $130. There are a
number of annealing kilns sold for glass
work that come in around $400 to $450,
and the programmable PMC kilns are
running around $550.