WHew536674@cs.com on sun 9 apr 00
Hi all,
To make a long story short, had been glaze firing in cone 9-10 gas reduction.
Moved to a new school to set up ceramics program, no gas, so I ordered the
Axner Super kiln (Olympic) fully loaded. Tried out some of the same glazes I
had been using and most turned out a lot better than expected. So I ordered
a little test kiln to quickly work on more cone 9 oxidation. Got the
impression that because it fires up so fast and cools down so fast, that the
tiles would look different than if I fired them in a regular glaze firing in
the Olympic. As a result, I have only used the test kiln one or two times to
test cone 9 glazes, and was not impressed. Wondering if anyone out there can
confirm this and have done glaze testing in a test kiln, and them fired it in
a BIG Olympic, (or other wise) and were there noticeable differences in the
results? I know, I could fire them in the test kiln, make another set and
fire them in the Olympic, but it takes a long time to fill it up and would
like to do some quick tests, but now I don't trust the results.
Thanks in advance
Joyce A.
WHew536674@cs.com
Jim Brooks on mon 10 apr 00
Joyce, I too have a small test kiln that fires too fast... For that reason, i
was hesitant to test glazes..Until, i realized that the kiln would not fire
any faster than i let it fire. So i leave it on Low longer..on Medium
longer.. and have even fired it off on medium.. Now i test and the test
closely resemble what i get in a large kiln.. Good luck..I use my small test
tkiln all the time now.. Jim ........in Dallas.
iandol on wed 12 apr 00
------------------
Subject: test kiln question
I recall that Bernard Leach gives an illustration of a diminutive test kiln =
made
from tiles and dry ash, fired with a pump up kero blowlamp. A reference =
which
might be useful to someone.
I think Joyce=92s experience confirms what has been said before about =
firing.
Although the cone may suggest that an equivalent amount of heat work has =
been
done by it=92s degree of bend, there may not have been time for the chemical=
magic
of the ingredients to become fully effective. My suggestion would be to time=
the
interval between the drop of the guard cone and that of the indicator cone
during a firing of the big kiln and to apply that time interval to the =
programme
of the test kiln. It may also pay to arrest the cooling rate of the test =
kiln as
well if the glazes need time for crystallisation to occur.
A direct comparison is not possible because the rates of heating and cooling
differ so much.
Hoping this information is useful to other members.
Best regards,
Ivor Lewis.
Linda Hamm on wed 12 apr 00
Got the
>impression that because it fires up so fast and cools down so fast, that
the
>tiles would look different than if I fired them in a regular glaze firing
in
>the Olympic.
Joyce
IMO a test kiln that fires and cools fast is perfect provided you have the
capability to match the firing schedule of your large kiln.
When I built a test kiln I designed it to fire up fast and cool fast so I
could test my glazes in a fast firing. I also installed a Pyrometer so I
could monitor the temperature curve. This allowed me to manipulate the
power and create a firing schedule that was within the capabilities of my
large kilns. The glazes fired in the large kilns were the same as the
tests.
Bob Hamm
Super Mud Works
Kelowna BC, Canada
email hamm@direct.ca
Kristina on tue 1 jun 04
I'm pretty much a firing newbie - I've been throwing for several years but
I finally decided to invest in the small kiln about 1.5 years ago (AIM
64J, 6.5"x6.5"x6.5"). Up until now I've just been firing bisqueware and
low-fire glazes with no problems. It usually takes ~1 hour to ramp up and
then ~2 hours to reach cone 04.
I recently bought some cone 5 glazes and thought I'd give it a try. Well
it took forever! I ramped up over about 40 minutes (faster because this
was a glaze load) but then it took an additional 7.5 hours to reach cone
5. Now I realize that cone 5 is a higher temp than cone 04, but really.
I thought the beauty of having a test kiln was that you could get it up to
temp quickly. Am I doing something wrong? Or are my expectations too
high?
I'd appreaciate any suggestions.
Kristina in California
Ivor and Olive Lewis on wed 2 jun 04
Dear Kristina,
The volume of your kiln is very small. So the volume of the insulation
in relation to the working volume is very large. Therefore, energy at
higher temperatures is being used to keep the insulation warm rather
than to heating the objects you are firing. In addition, the ratio of
outer surface area to inner volume is much larger than it would be for
a larger kiln because both need the same thickness of insulation to
contain heat and maintain a temperature at the same rate of energy
input. Heat stored in the insulation tends to be conducted away at a
faster rate from a small kiln.
The advantage of a small test kiln is that it will cool quickly and
you can load it and use it more frequently, on a daily basis. But if
you had a large kiln, say, over 10 cubic foot it might take you weeks,
even months to accumulate enough ware for a firing. So by having
firings on a daily basis you accumulate knowledge of your methods and
materials at an accelerated rate.
Accept things for what they are and exploit their advantages
Best regards,
Ivor Lewis. Redhill, South Australia
Potters Council Member
.
Arnold Howard on wed 2 jun 04
Kristina, I am not familiar with your kiln. I don't know how many amps it
pulls. Generally, a kiln that small should be able to fire rapidly on even a
120 volt, 15 amp circuit.
One way to tell if the kiln is firing at its maximum rate is to listen to it
near the end of the firing. If the kiln is digital, the relays should no
longer be clicking. They should remain on continuously. If the kiln uses
infinite control switches, you should no longer hear the switches cycling.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net
From: "Kristina"
> I'm pretty much a firing newbie - I've been throwing for several years but
> I finally decided to invest in the small kiln about 1.5 years ago (AIM
> 64J, 6.5"x6.5"x6.5"). Up until now I've just been firing bisqueware and
> low-fire glazes with no problems. It usually takes ~1 hour to ramp up and
> then ~2 hours to reach cone 04.
>
> I recently bought some cone 5 glazes and thought I'd give it a try. Well
> it took forever! I ramped up over about 40 minutes (faster because this
> was a glaze load) but then it took an additional 7.5 hours to reach cone
> 5. Now I realize that cone 5 is a higher temp than cone 04, but really.
> I thought the beauty of having a test kiln was that you could get it up to
> temp quickly. Am I doing something wrong?
Peggy Bjerkan on wed 2 jun 04
I use one of these small kilns often to fire small pieces and tests. It
sounds to me like your kiln needs a new set of elements!
Good luck,
Peggy Bjerkan
Napa Valley, California
www.maskwoman.com
----- Original Message -----
From: "Kristina"
To:
Sent: Tuesday, June 01, 2004 1:22 PM
Subject: Test Kiln question
> I'm pretty much a firing newbie - I've been throwing for several years but
> I finally decided to invest in the small kiln about 1.5 years ago (AIM
> 64J, 6.5"x6.5"x6.5"). Up until now I've just been firing bisqueware and
> low-fire glazes with no problems. It usually takes ~1 hour to ramp up and
> then ~2 hours to reach cone 04.
>
> I recently bought some cone 5 glazes and thought I'd give it a try. Well
> it took forever! I ramped up over about 40 minutes (faster because this
> was a glaze load) but then it took an additional 7.5 hours to reach cone
> 5. Now I realize that cone 5 is a higher temp than cone 04, but really.
> I thought the beauty of having a test kiln was that you could get it up to
> temp quickly. Am I doing something wrong? Or are my expectations too
> high?
>
> I'd appreaciate any suggestions.
>
> Kristina in California
>
>
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