DJ Brewer on sat 7 nov 09
The Skutt Kilnmaster 1027 I got is a cone 10 kiln but I have heard both
teachers and potters say not to fire it to cone 10 frequently. They said
that it will wear out the elements faster if you fire it to cone 10, and
recommend that it be used only for midrange firings.
So my question is -- then why make it a cone 10 kiln at all? If it
cannot be fired often to cone 10, what is the point of calling it a cone
10 kiln? It seems that if a kiln is designed for cone 10 firings, it
should be made durable enough to do so.
Is it true that a cone 10 kiln should not be used often to fire to cone
10, but rather, just be used for midrange?
Confused and Bewildered!
DJ
Arnold Howard on wed 11 nov 09
From: "Fuzzy Chef"
> As long as you're answering questions ... what's the
> median difference
> in coil lifetime between firing to Cone 10 vs. Cone 6 in a
> Paragon kiln
> which is rated to Cone 10 (and has 3" brick)?
Many factors affect element life besides the cone
temperature--type of clay, element wire gauge, hold time,
controlled cooling, kiln wall thickness, and even low
voltage. So it is difficult to say. Nevertheless, here is a
general estimate that Tom Buck sent me some time ago. It
comes from Kanthal:
Kanthal A-1 wire elements:
Firing to Cone06/05 (1000+ oC, 1832+ oF) repeatedly ONLY,
ie, a bisque firing, the lifetime is over 1000 firings under
normal conditions (claybody is low on sulfur and nitrogen
materials, and silico-fluorides).
Firing to Cone 6 (1240 oC, 2264 oF), the lifetime is 200
firings.
Firing to Cone 10 (1305 oC 2380 oF), the lifetime drops to
120 firings.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Fuzzy Chef on wed 11 nov 09
Arnold,
> Firing to Cone 6 (1240 oC, 2264 oF), the lifetime is 200
> firings.
>
> Firing to Cone 10 (1305 oC 2380 oF), the lifetime drops to
> 120 firings.
Wow, thank you! That's very helpful!
(btw, my Paragon Kiln is over 15 years old and has been completely
rebuilt twice. Not good for your bottom line, but a testimonial to your
quality)
Do you have any comment on the assertion that the on/off cycles produced
by computer kiln controllers shorten the lifespan of coils as compared
with straight-through firings?
--Josh Berkus
Jess McKenzie on wed 11 nov 09
As we suspected, this subject has appeared before, as
has the name, Tom Buck. Mr. Buck spoke on electric
reduction in previous List msgs--OCT'98 for instance.
He seems to be a lot more informed than most of the
respondents so far. Please look for "Tom Buck" at:
http://www.potters.org/subject16148.htm/
~joan and jess
Arnold Howard wrote:
Clayart@LSV.CERAMICS.ORG
[ Double-click this line for list subscription
options ]
http://www.potters.org/subject16148.htm/
Many factors affect element life besides the cone
temperature--type of clay, element wire gauge, hold
time, controlled cooling, kiln wall thickness, and
even low voltage. So it is difficult to say.
Nevertheless, here is a general estimate that Tom
Buck sent me some time ago. It comes from Kanthal:
Kanthal A-1 wire elements:
Firing to Cone06/05 (1000+ oC, 1832+ oF) repeatedly
ONLY, ie, a bisque firing, the lifetime is over 1000
firings under normal conditions (claybody is low on
sulfur and nitrogen materials, and silico-fluorides).
Firing to Cone 6 (1240 oC, 2264 oF), the lifetime is
200 firings.
Firing to Cone 10 (1305 oC 2380 oF), the lifetime
drops to 120 firings.
Sincerely,
Arnold Howard Paragon Industries, L.P., Mesquite,
Texas USA ahoward@paragonweb.com / www.paragonweb.com
John Rodgers on wed 11 nov 09
Arnold,
Please discuss the firing cost calculation operations that the newer
controllers are capable of. This is one sweet feature. Also, many would
like to know how far back they can be retrofitted..
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
Arnold Howard wrote:
> From: "Fuzzy Chef"
>> As long as you're answering questions ... what's the
>> median difference
>> in coil lifetime between firing to Cone 10 vs. Cone 6 in a
>> Paragon kiln
>> which is rated to Cone 10 (and has 3" brick)?
>
> Many factors affect element life besides the cone
> temperature--type of clay, element wire gauge, hold time,
> controlled cooling, kiln wall thickness, and even low
> voltage. So it is difficult to say. Nevertheless, here is a
> general estimate that Tom Buck sent me some time ago. It
> comes from Kanthal:
>
> Kanthal A-1 wire elements:
>
> Firing to Cone06/05 (1000+ oC, 1832+ oF) repeatedly ONLY,
> ie, a bisque firing, the lifetime is over 1000 firings under
> normal conditions (claybody is low on sulfur and nitrogen
> materials, and silico-fluorides).
>
> Firing to Cone 6 (1240 oC, 2264 oF), the lifetime is 200
> firings.
>
> Firing to Cone 10 (1305 oC 2380 oF), the lifetime drops to
> 120 firings.
>
> Sincerely,
>
> Arnold Howard
> Paragon Industries, L.P., Mesquite, Texas USA
> ahoward@paragonweb.com / www.paragonweb.com
>
>
Arnold Howard on thu 12 nov 09
From: "Fuzzy Chef"
> Do you have any comment on the assertion that the on/off
> cycles produced
> by computer kiln controllers shorten the lifespan of coils
> as compared
> with straight-through firings?
I believe it's true. I don't think it's much of an issue
with pottery kilns, though, because they don't cycle on and
off during much of a firing. Glass fusing kilns cycle more
than pottery kilns, because glass artists use very long
annealing cycles that wear out relays far faster than do
pottery kilns. Heating elements in glass kilns last a long,
long time, nevertheless, because glass is fired to low
temperatures. 1400 - 1500F is typical.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Arnold Howard on thu 12 nov 09
From: "John Rodgers"
> Please discuss the firing cost calculation operations
> that the newer controllers are capable of. This is one
> sweet feature. Also, many would like to know how far back
> they can be retrofitted..
I've wanted this feature for many years. We added it about
two years ago. Sentry 2.0 controllers that have the cost
calculator will show "Firing Cost" on the 8 key.
In Options, enter the cost of electricity and the wattage
listed on the kiln's electrical data plate. The controller
with then add up the total time the elements were powered
during a firing and multiply that amount by the cost of
electricity. The system works with U.S. and Canadian
dollars, Euro cents, British pence, Indian paisas, or any
other system that is based on 100. (Libyan dirham: divide
the cost results show in the display by 10.)
The older Sentry controller can be upgraded with the new
software. However, this will require a new circuit board.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
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