Sharon Miranda on thu 15 feb 01
Dear clayarters:
Here I am making great gobs of pots just to fill a kiln so I can test
glazes. And thinking maybe I should invest in a test kiln. I've always
thought a test kiln wouldn't give accurate readings, since it must fire so
much faster.
Columbus Clay (my supplier) has Vulcan test kilns for $179. But I'd have to
also buy a pyrometer setup making it much more expensive.
What are your opinions on test kilns? What good brands are out there? Can I
slow down the firing of test pieces to get a pretty accurate reading? (And
how does one do this?) Is this piece of equipment a pretty standard and
necessary thing to have? I ran into such a stumbling block when the one
glaze I was
counting on for most of my pots stopped working (the gerstley borate
syndrome).
Thanks in advance for any advice...
Sharon Miranda
sharonmiranda@earthlink.net
Dennis Mummert on fri 16 feb 01
Sharon;
I have that kiln, in fact, I used it for 2 years exclusively to fire bisque
and glazes, as I could not afford anything bigger. It limited the size of
pieces I could produce!
The man behind Vulcan Kilns is Jeff Williams, and he lives right here in
Dayton about 20 miles from me. I went down to his shop and picked mine up.
The pyrometer is not an absolute necessity. A kiln sitter is, though. I
got the pyrometer, and the only thing I use it for now is to check the
progress of the kiln. The first few firings I gathered some time/temp
curve data, but now unless I am profiling a firing or trying to follow a
specific curve, I mostly ignore it.
This is a fast firing kiln. It will hit cone 06 in about 3 hours with the
lid propped up a quarter inch and the peephole open. I use it that way to
fire red glazes.
If you're using switches instead of infinite controls (which are really
only oven controls), and you want to reproduce a heating curve, then yes, a
pyrometer is called for. There is something to think about here, though.
You will need to plug this kiln into a 20 amp 110V outlet, and most normal
receptacle circuits are 15 amp. Also, it has, I think, only a 5 foot cord.
I have set mine on concrete blocks on my workbench.
Dennis Mummert
Earthen Fire Studios
Fairborn, Ohio
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Sharon Miranda
Sent: Thursday, February 15, 2001 10:49 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: test kiln advice
Dear clayarters:
Here I am making great gobs of pots just to fill a kiln so I can test
glazes. And thinking maybe I should invest in a test kiln. I've always
thought a test kiln wouldn't give accurate readings, since it must fire so
much faster.
Columbus Clay (my supplier) has Vulcan test kilns for $179. But I'd have to
also buy a pyrometer setup making it much more expensive.
What are your opinions on test kilns? What good brands are out there? Can I
slow down the firing of test pieces to get a pretty accurate reading? (And
how does one do this?) Is this piece of equipment a pretty standard and
necessary thing to have? I ran into such a stumbling block when the one
glaze I was
counting on for most of my pots stopped working (the gerstley borate
syndrome).
Thanks in advance for any advice...
Sharon Miranda
sharonmiranda@earthlink.net
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John Hesselberth on fri 16 feb 01
Sharon Miranda wrote:
>What are your opinions on test kilns? What good brands are out there? Can I
>slow down the firing of test pieces to get a pretty accurate reading? (And
>how does one do this?) Is this piece of equipment a pretty standard and
>necessary thing to have? I ran into such a stumbling block when the one
>glaze I was
>counting on for most of my pots stopped working (the gerstley borate
>syndrome).
Hi Sharon,
Test kilns work great and the results can be reproduced in a large kiln
IF you closely match the heating AND, probably more importantly, the
cooling rate of your large kiln. I let a computer do this for me.
Others do it manually. I am happy with my Olympic doll kiln. It cost a
little over $500 computer included. There are other good brands also I
am sure.
Regards, John
"The life so short, the craft so long to learn." Hippocrates, 5th cent.
B.C.
Paul Taylor on fri 16 feb 01
Dear sharon
Do not be too worried about an uneven firing in a test kiln . you just have
to know what the temperature is where - using cones. This means you get the
glaze fired under slightly differing conditions which can save you years
experimenting with different firings.
However some prefer to adjust the glaze to a rigid firing schedule and
believe different firing unnecessary for any glaze . You pays your money and
-- -------
Regards from Paul Taylor
http://www.anu.ie/westportpottery
Alchemy is the proof that economics is not a science.
> From: Sharon Miranda
> Reply-To: Ceramic Arts Discussion List
> Date: Thu, 15 Feb 2001 22:48:39 -0500
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: test kiln advice
>
> Dear clayarters:
>
> Here I am making great gobs of pots just to fill a kiln so I can test
> glazes. And thinking maybe I should invest in a test kiln. I've always
> thought a test kiln wouldn't give accurate readings, since it must fire so
> much faster.
> Columbus Clay (my supplier) has Vulcan test kilns for $179. But I'd have to
> also buy a pyrometer setup making it much more expensive.
>
> What are your opinions on test kilns? What good brands are out there? Can I
> slow down the firing of test pieces to get a pretty accurate reading? (And
> how does one do this?) Is this piece of equipment a pretty standard and
> necessary thing to have? I ran into such a stumbling block when the one
> glaze I was
> counting on for most of my pots stopped working (the gerstley borate
> syndrome).
>
>
>
> Thanks in advance for any advice...
> Sharon Miranda
> sharonmiranda@earthlink.net
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Carol Sandberg on mon 19 feb 01
----- Original Message -----
From: Carol Sandberg
To: Ceramic Arts Discussion List
Sent: Sunday, February 18, 2001 12:52 AM
Subject: Re: test kiln advice
On Thursday, February 15, 2001 10:48 PM, Sharon Miranda
sharonmiranda@EARTHLINK.NET wrote:
>What are your opinions on test kilns? What good brands are out there?
>Is this piece of equipment a pretty standard and necessary thing to have?
Hi Sharon,
I can't imagine getting along without a test kiln. The first one I
purchased was called a "Norman" and is still working fine after many years
of testing and firing small pieces. The firing chamber measures 8"x8"x (4
and 1/2)" tall. There is a blank ring which can be used to extend the
height
another 2". I purchased a second test kiln made by Roger Bachman, same
design, same dimensions, and it works great too. The design of these two
kilns is modular; a firebrick element ring sits on a firebrick base which is
identical to the lid. These kilns can fire extremely fast; but you control
the rate of heat increase with a numbered control dial and your firing
schedule. They can go to cone 10. These kilns, when I bought them , were
around $100-125.
Years later, I was given a kiln wich is similar in design but larger, with
more elements. It is a very old model made by Amaco, and barely reaches
cone 06. I think it is an antique (it acts like it). But It works fine for
luster firings (018).
I log all my firings in a notebook and identify the kiln by it's name
(Norman, Roger or Laura-the person who gave me the antique.) Keeping strict
records has been extremely useful. I can refer back to see how long a
firing is going to take, how full the kiln was, etc.etc. The Roger kiln
fires faster than Norman does, and Laura plods along at a snail's pace.
Lately I have been thinking about replacing Laura's elements. I don't know
if they have ever been changed. (Kinda like oil in a car.) But I don't drive
it (oops) fire it very often.
I always fire with witness cones since the kilns' sizes prevented me from
installing kiln sitters. Sometimes, that seems like an inconvenience, but
keeping an eye on the firings has made me very familiar with the color in
the
kiln at each temperature range, and that's invaluable info. I make cone
packs by extruding small square clay bars and imbedding the cones in them,
well in advance. I keep a box of ready cone packs on a shelf in the kiln
room.
To make testing glazes less of an interruption in my work rhythm, I
periodically extrude lengths of tile about 2 inches wide by 3 inches long .
To mark them with the clay body, I stamp the abbreviated name into the
clay. Later, that serves to tell me how the glaze performs over texture.
Then I dry them, bisque fire, and put them away in a drawer for future use.
To support the tiles upright in the test kilns, I made several tile holders
which are grooved slabs about 2 and 3/4" x 6and 1/2" by 5/8" thick (fired).
There are 3 grooves per holder, which span the length of the holder. I glaze
a test tile only on the upper 4/5 of the tile. Where the unglazed bottom is
supported in the groove, I write identification with underglaze pencil. I
made the grooved tile holder by extruding through a die I made which has one
straight side and the other side is notched like the edge of a trowel.
Painting kiln wash on the holders is essential. If I think a glaze is going
to run at all, I leave more room at the bottom of the tile, or test it flat
first. When I do a glaze firing in the test kiln, I always do a soak at the
end of the firing.
I don't think you will ever regret investing in a test kiln, whether you
purchase a small one, like mine, or a slightly larger model with a kiln
sitter.
Good Luck,
Carol, in Indiana
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