Lajos Kamocsay on tue 23 apr 02
Hello,
Is there a problem with glaze firing at a rate of 500-600 degrees per =
hour? Is there any reason to have longer firings?
I know that bisque firing should be done slow because of a lot of =
reasons... but how about glaze loads?
Thanks,
Lajos
KLeSueur@AOL.COM on tue 23 apr 02
Pitting, cratering, and pinholing are just a few of the problems with fast
firing. Keep in mind that a chemical like whiting looses half of its
molecular weight during firing. That's a lot of gases to burn off.
When I consulted Jeff Zameck because of surface problems he recommended and
increase of 65 degrees F per hour from cone 05 tp cone 10. Following his
advice eliminated most of my problems.
Kathi LeSueur
Kathi LeSueur
Tony Ferguson on tue 23 apr 02
Lajos,
Firing should be slow going up and slow cool going down. I like 100 to 150
degrees an hour. Like lov'in. But, if the fast track works without any
glaze clay fit problems or pieces blowing up during the firing or a year
from when you fire them, then go for it.
Thank you!
Tony Ferguson
Stoneware, Porcelain, Raku
www.aquariusartgallery.com
Workshops available
218-727-6339
315 N. Lake Ave
Apt 312
Duluth, MN 55806
----- Original Message -----
From: "Lajos Kamocsay"
To:
Sent: Tuesday, April 23, 2002 11:54 AM
Subject: fast glaze firing
Hello,
Is there a problem with glaze firing at a rate of 500-600 degrees per hour?
Is there any reason to have longer firings?
I know that bisque firing should be done slow because of a lot of reasons...
but how about glaze loads?
Thanks,
Lajos
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iandol on wed 24 apr 02
Dear Lajos Kamocsay,
You ask about rapid rates of heating. Currently in the industrial sector =
there are initiatives where porcelain is being glost fired to >1300C, =
cold to cold in times as short as two hours. But the whole system, both =
plant and product is designed to do just that. I think the stuff is a =
bit bland. Stark white and glossy
The computer programs include arrests which permit phase changes to =
occur without inducing stress which would cause cracking and the =
materials are engineered to eliminate crazing.
Perhaps fast firing is not such a big problem as fast cooling.
Interesting thoughts though.
Best regards,
Ivor Lewis.
Jeff Tsai on wed 24 apr 02
Whoever said pinholing would be a problem is definitely right on.
500-600 isn't too fast for some glazes. I know that some commercial low fire
glaze makers make red glazes that require fast firings in order for the
glaze
to even turn red (fast meaning 4 hours to cone 1780)
I've seen glazes come out fine in fast firings, my gloss glazes weren't so
glossy, my crawl glazes weren't always crawling, but other than that, I've
seen relatively few problems. I use a baby electric kiln to test glazes
sometimes, and that thing can reach cone 06 in two hours. That's where I
figured out that crawl glazes don't crawl so well and gloss glazes don't
gloss so well in fast firings. beyond that, can't tell you much.
I know that I wouldn't fire too many large sculptural pieces that fast
though.
-jeff
Wanda Holmes on wed 24 apr 02
In addition to possible problems with the glaze, such as pinholing, I would
be concerned about excessive warping of the work as it matured. wanda
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Snail Scott on wed 24 apr 02
At 11:54 AM 4/23/02 -0700, you wrote:
>I know that bisque firing should be done slow because of a lot of
reasons... but how about glaze loads?
Loads of already-bisqued clay can be fired pretty
dang fast. You may want to add a nice long soak
at the top to compensate, though.
-Snail
Longtin, Jeff on wed 24 apr 02
Just when you think the rules will never change...
Years ago I had a studio next to a production potter who threw 200-300 pots
a day.
(He produced steins for the Renn Fest circuit.)
He was running behind one year so he tried loading the kiln with leatherhard
steins.
Leatherhard mind you.
He packed the kiln.
Of course he candled it for a little bit, a few hours or so, but still he
basically loaded wet.
He lost only a handful!
Truely amazing!
He knew he'd lose a few but to lose ONLY a few blew his mind. I think the
kiln, a Skutt 1227, held 150 steins or so.
So I tried it myself.
I slip cast so my pots are thinner generally. I packed a bunch of
leatherhard pots into the kiln, threw it on high
and fired it off in about 5 hours, a bisque firing. Lost one pot.
I don't make a habit of rushing a firing, of course, but once in awhile...
Jeff Longtin
p.s. wasn't someone experimenting with rakuing wet pots years ago? I
remember seeing something in ceramics monthly.
-----Original Message-----
From: Snail Scott [mailto:snail@MINDSPRING.COM]
Sent: Wednesday, April 24, 2002 10:46 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: fast glaze firing
At 11:54 AM 4/23/02 -0700, you wrote:
>I know that bisque firing should be done slow because of a lot of
reasons... but how about glaze loads?
Loads of already-bisqued clay can be fired pretty
dang fast. You may want to add a nice long soak
at the top to compensate, though.
-Snail
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Earl Brunner on wed 24 apr 02
I have never done this but I have heard discussions about it. I have heard
that
you can actually put WET pots in a kiln, and candle them dry, the deciding
factor
being the control of the humidity within the kiln. By controlling the
moisture
content of the atmosphere in the kiln you are supposed to be able to in
affect
force dry them in the kiln without blowing them up. But I have never done
it. If
you are doing this with an electric kiln I would wonder about the affect of
the
moisture on the hot elements......
"Longtin, Jeff" wrote:
> Just when you think the rules will never change...
> Years ago I had a studio next to a production potter who threw 200-300
pots
> a day.
> (He produced steins for the Renn Fest circuit.)
> He was running behind one year so he tried loading the kiln with
leatherhard
> steins.
> Leatherhard mind you.
> He packed the kiln.
> Of course he candled it for a little bit, a few hours or so, but still he
> basically loaded wet.
> He lost only a handful!
> Truely amazing!
> He knew he'd lose a few but to lose ONLY a few blew his mind. I think the
> kiln, a Skutt 1227, held 150 steins or so.
>
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Snail Scott on thu 25 apr 02
At 03:22 PM 4/24/02 -0500, you wrote:
>He was running behind one year so he tried loading the kiln with
leatherhard
>steins.
>He lost only a handful!
I've heard of this being done by some of the
old-style folk potters in the southeast. It
apparently works only if absolutely everything
in the kiln is wet. No half-and-half, and it
won't work if it's mostly dry. Gotta be wet!
I've heard some people theorize that it's got
something to do with steam pressure, but I
dunno. Most kilns don't seem tight enough
for that. Anyone heard a better theory?
-Snail
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