Felicity Rich on sun 13 aug 06
Does firing glazed ware in an electric kiln reduce the life of the kiln? If so why?
Arnold Howard on mon 14 aug 06
From: "Felicity Rich"
> Does firing glazed ware in an electric kiln reduce the
> life of the kiln? If so why?
As long as the kiln is vented, firing glazed ware is fine in
an electric kiln.
Another interpretation of your question is, "How do you get
the longest life out of an electric kiln?" Here is a set of
guidelines that I gave out at a school last summer:
1) Use the stand supplied with the kiln. The kiln must be
level. Place shims under a stand leg, if necessary, to
stabilize a kiln.
2) Kiln wash the shelves and the kiln bottom. Kiln wash
protects the shelves and bottom from dripping glaze. Remove
embedded glaze before the next firing. Reapply kiln wash to
that area.
3) Keep kiln wash away from elements. Kiln wash and glaze
will destroy elements. Keep kiln wash off the kiln walls and
underside of shelves.
4) Do not let anything touch the firebrick walls during
loading and unloading. Allow only the most careful
assistants to load and unload your kilns.
5) Do not lean too heavily against the kiln while loading.
The bricks are fragile.
6) Do not bump anything against the Kiln Sitter tube or
digital thermocouple.
7) Lower the lid gently. Do not store anything on the lid.
Jarring the lid can cause cracks, which will later
contaminate glazes with powdered brick.
8) Keep the cord set away from the kiln's hot sides. The
kiln case can burn the cord set.
9) Kiln Sitter: Check the adjustment every month using the
firing gauge. Order a firing gauge if you do not have one.
10) Repair bulging elements before the next firing. Unplug
the kiln and heat the element with a propane torch, and then
press the element back into the groove.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
William & Susan Schran User on mon 14 aug 06
On 8/13/06 10:20 PM, "Felicity Rich" wrote:
> Does firing glazed ware in an electric kiln reduce the life of the kiln? If
> so why?
It's probably more the effects of high heat that degrade the components of
the kiln as much as anything. The elements will be the part that suffers the
most wear & tear. Other metal parts that may be exposed to the heat and
moisture will also wear/corrode.
Some ingredients in glazes may vaporize or even spit out may affect the life
of the brick and again moisture, from the atmosphere (if the kiln is in an
non-conditioned environment) and from the clay.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
dwichman@frontiernet.net on tue 15 aug 06
Hi Arnold,
I had heard that using your kiln to dry your ware is also hard on the
elements, is this true? If so, does using a vent alleviate this and
keep the water vapor from doing harm?
Thanks,
Debi
Arnold Howard on thu 17 aug 06
From: "dwichman@frontiernet.net"
> Hi Arnold,
>
> I had heard that using your kiln to dry your ware is also
> hard on the
> elements, is this true? If so, does using a vent
> alleviate this and
> keep the water vapor from doing harm?
Yes, drying greenware in the kiln is hard on the elements,
because firing time is extended, causing the elements to
work harder.
If you have ever noticed water dripping around the kiln, it
is probably due to moisture in the ware. The typical 8-sided
kiln can absorb 50 pounds of moisture in the firebricks.
This reduces the insulating capacity of the firebricks and
slows down the firing. Not only is this hard on the
elements; it also wastes electricity, because it takes a lot
of power to turn water into steam.
So even though digital kilns now include a preheat feature
to candle the ware, it is not meant to be used for extended
periods.
Leave a downdraft vent on during preheat. This will rust the
vest faster, but it will help remove moisture from the kiln.
I would be very interested to hear comments from others on
this topic.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
William & Susan Schran User on thu 17 aug 06
On 8/17/06 11:22 AM, "Arnold Howard" wrote:
> I would be very interested to hear comments from others on
> this topic.
My question would be: Why the heck are you drying pots in the kiln?
Isn't allowing them to dry in the open air good enough?
I NEVER dry pots in the kiln and my students know this. Their greenware is
to be completely dry and ready to be fired before they place it on the
"greenware - ready for firing" shelves.
Rushing drying will shorten the life of your kiln, the kiln vent and puts
greater stresses on the pots.
I have a similar issue with folks who want to remove work from a hot kiln
before the pots can be held in one's bare hands, but that's another subject.
Plan ahead and be patient, that's all.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
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