David Hendley on wed 13 oct 04
----- Original Message -----
> Yee-haw! A craftsman can tell the temperature by the color
> in the kiln. ;-)
You got me, Lee. I'm just not a craftsman. Guess I never will
be, since I plan to continue firing with cones.
Industry did not get me to bisque at hotter temperatures.
Being too "clumsy or lazy" to learn to work with under-fired
bisque didn't ether.
Pots that cracked on cooling in the bisque kiln did.
Glaze application thickness is also important to me. And
actually a higher, less absorbent bisque gives one more
control over the thickness of the glaze. A second's difference
in timing with a highly absorbent pot can make a big
difference in the glaze thickness, while a second's difference
when working with a tighter pot won't matter, since it is
already held in the glaze slop for a long time.
It's like 1/500th of a second doesn't matter much if your
camera is at f 22, but can make quite a difference at f 2.4.
Maybe I could import my clay from Japan, since my lousy
clay has to be bisque fired 165 degrees C hotter than cone 012
to work properly.
I could probably save $2.40 in electricity every firing.
Maybe the clay would make me learn to stop being a clumsy
and lazy American.
It might even make me a craftsman.
Forget everything I said earlier. Bisque fire however-the-hell
you like.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
From: "Lee Love"
To:
Sent: Wednesday, October 13, 2004 10:46 AM
Subject: Re: bisque firing ~ listen to Ron Roy?
> David Hendley wrote:
>
> >
> >I had gotten cheap and lazy.
> >After decades of bisque firing, I thought I knew what cone 06
> >looked like, so I stopped using a cone and fired according to
> >time and atmosphere color.
> >
> >
>
> Yee-haw! A craftsman can tell the temperature by the color
> in the kiln. ;-) Fukiyan was retired Foreman I worked with, 78 years
> old, started with Hamada at the age of 14. He ONLY judged the
> temperature in a noborigama bisque by the color in the chamber. The
> largest osara (the $30,000.00 ones) and the large tsubo were bisqued for
> noborigama glaze firing in the gas kiln, but everything else for the
> noborigama was bisqued to red heat in the noborigama. The gas kiln
> bisque was done by apprentices to temperature according to an analog
> pyrometer. But the hottest part in the large gas kiln was only up to
> cone 012.
>
> In Japan, they bisque at a lower temp. I believe it is
> industry that got us bisquing at higher temps. Glaze thickness
> application is very important to my teacher's work. The lower
> bisque, I am guessing, gives him more control over the thickness of the
> glaze.
>
> >Gradually, the temperature dropped. Hey, what's wrong with
> >saving a few bucks worth of electricity?
> >
> >All went fine until I started making some large bowls (16"
> >diameter and greater). More than half cracked. Cooling cracks
> >which ran up the side from foot to rim.
> >
> >
> Lower bisque is softer, so it isn't for the clumsy or lazy, but
> people learn to work with it here in Japan.
>
> As I said previously, the hot part of my woodkiln bisques to
> 012. The bottom front is cooler, but not as cool as the coldest spots
> in the noborigama bisque.
>
> >see, there really is a pretty great difference in the strength of ware
> >fired at C 08 vs. C06 - at least with my claybody. The stronger
> >clay can take the phase changes on the way down, but the
> >flimsy soft bisque cannot.
> >
> >
> I've never had these kinds of cracks in my lower
> temperature bisque and I never saw them at my teacher's studio either.
> I have been bisquing to 012 since '91. . Could it be a fault of
> the clay you are using? Does it have a high silica content?
>
>
> Difference between cone 06 and cone 06.5 isn't going to
> make a noticeable difference in energy usage. But the difference
> between cone 06 and 012 can be measured on you meter.
>
> --
>
> in Mashiko, Japan http://mashiko.org
> http://www.livejournal.com/users/togeika/ WEB LOG
> http://public.fotki.com/togeika/ Photos!
>
>
Lee Love on fri 15 oct 04
David Hendley wrote:
>You got me, Lee. I'm just not a craftsman. Guess I never will
>be, since I plan to continue firing with cones.
>
>
I realized quickly, that I could never be a shokunin.
The big lesson I learned by watching the "Old Timers", is that
many of our senses are atrophied, simply because we don't use them.
MacKenzie wrote an essay about how we protect our lives from discomfort
by wrapping our sensibilities in plastic, glass. chrome and stainless
steel. But this protection keeps us from learning a tactile vocabulary.
Machines and tools of "convenience" can do the same to our
ability to discern. When we don't exercise faculties, we loose the
ability to use them.
>Glaze application thickness is also important to me. And
>actually a higher, less absorbent bisque gives one more
>control over the thickness of the glaze.
>
I explained how the glaze absorption in a low
bisque can be controlled by sponging the bisque with water.
Actually, this method gives you MORE control over the glaze thickness,
allowing you to vary the thickness to a large degree simply by how you
sponge the bisque, rather than having to add or remove water from the
glaze. This also leads into the example I have spoken about here
before: my eppifany about achieving proper glaze thickness.
One of my jobs during glazing at my teacher's workshop
was sponging the bisque before it was glazed. I got very skillful at
doing this (it is strange to be very good at something that has so few
practical applications ;-) ) For three years, I watched the Foreman,
Retired Foreman and Sensei do scratch tests to check the thickness of
the glazes. At first, I wondered why they wasted their time doing
this, when they could use a hydrometer to measure the glaze. But I
sat between the Foreman and Sensei and I was able to watch these
"scratch tests" every time they were done. I paid attention.... At
first, I couldn't tell the difference between one test and another.
I thought it was Mumbo Jumbo. But after watching these test for about
3 or 4 months, and trying to guess what the Foreman or Sensei would
decide, I found that I could finally "guess" what they would decided
about 9 times out of 10. Yes, I am most certainly a slow learner.
Also, after doing this for a time, I realized that the
scratch test was much more accurate for measuring the actual thickness
of the glaze on the ware than measuring the glaze thickness with a
hydrometer. But it takes"eye training." A hydrometer is easier to
use, but it can be a barrier to learning too.
>Maybe I could import my clay from Japan, since my lousy
>clay has to be bisque fired 165 degrees C hotter than cone 012
>to work properly.
>
*Ha ha!* I don't really think this is necesarry, do you?
>Forget everything I said earlier. Bisque fire however-the-hell
>you like.
>
*Grin* Yes. Do what works for you.
I only spoke up because what was being said
flys in the face of what I do every firing.
Hey, my wood for a glaze firing used to cost me
about $14.00 per firing, just for the delivery. But now, we get
the same wood, but after the pallet maker uses the biggest pieces.
(there is not so much wood cutting now.) He is not charging for
delivery because it costs him less to truck it my yard than it does for
him to take to the dump to be burned, or to pay someone to burn it at
his workshop.
--
Lee in Mashiko, Japan http://mashiko.org
http://www.livejournal.com/users/togeika/ WEB LOG
http://public.fotki.com/togeika/ Photos!
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