clennell on thu 17 nov 05
Mel, Mary and Wes, Hank and Phil et all- You're all amazing! What a great
collective genius. You've given me more questions that I will watch for on
the next firing in about 2 weeks. i can't remember the temperature drop per
stoke being greater than usual or the rate of rise during the reduction,
neutral, oxidation cycle being more. heck' I can't remember the snap,
crackle, pop either! The idea that perhaps the steam from the wood is
increasing the draft of the kiln is really interesting. Perhaps this is what
Hank has been doing with his brine soak. For those with short wood kiln
chimneys I wonder if the wood soaked in brine may save you time on a ladder.
It is true the back of the kiln was also unusally hot with a good Cone 11
near the back wall. Wish I could fire tomorrow armed with these new
questions.
would an MFA student get an answer this quick? He/she would if they knew
where to ask- Clayart U.
cheers and thanks.
tony
Tony and Sheila Clennell
Sour Cherry Pottery
4545 King Street
Beamsville, Ontario
CANADA L0R 1B1
http://www.sourcherrypottery.com
http://www.sourcherrypottery.com/current_news/news_letter.html
Lee Love on sun 20 nov 05
Ivor and Olive Lewis wrote:
>
> Which is why potters need to rely on good Science and not Common Sense
> to sort these problems out.
>
We can use technological theory when we have enough data.
Sometimes, we simply use "pre-scientific" experience. For example, see
below:
> What is certain is that a wood firing is a dynamic, intermittent,
> irregular process whose complexity is increased not only by variations
> in kiln design but by differing fuels and atmospheric conditions.
>
That is why modern studio artists use them. The ancestors would
prefer modern kilns, with less variation , I am sure. The evolution
of kilns have been toward more predictability and control. The end
product we see in ceramic industry.
> I am sure you would never commence a firing using wet wood. I am
> equally sure you know the best time to introduce that resource in your
> firing program.
>
Actually, I do. I learned firing my teacher's
noborigama: you don't want a fast heat climb in the begining, so you
use old, large diameter, punky wood under the firegrates. Some
folks build the fire outside the firebox at first, especially if you
have work in the firebox. I stoke large green wood and rotten wood
under the grates at the front of the firebox until I reach 600*C.
This assures that bisque and single fire work will not be hit by the
flames early. It also creates a nice bed of coals.
--
Lee Love
in Mashiko, Japan http://mashiko.org
http://seisokuro.blogspot.com/ My Photo Logs
"Human subtlety will never devise an invention more beautiful,
more simple or more direct than does Nature,
because in her inventions, nothing is lacking and nothing is superfluous."
--Leonardo da Vinci
Ivor and Olive Lewis on sun 20 nov 05
Dear Lee Love ,
You say ...."Actually, when I stoke wet wood, I get a large heat jump. =
Defies common sense, doesn't it? Other people who wood fire have noticed =
the same thing."....
Which is why potters need to rely on good Science and not Common Sense =
to sort these problems out. Answers are readily accessible if you apply =
Basic Principles of Physics and Chemistry. Strange though it may seem, =
understanding the distinction between Heat and Temperature is crucial to =
solving questions about Kiln Behaviour. People who do not know the =
difference and use the terms indiscriminately cause confusion in =
discussions. Another concept disregarded in considering what is =
happening when water is introduced into a wood firing is "Change of =
State" and the energy interactions in those processes.
What is certain is that a wood firing is a dynamic, intermittent, =
irregular process whose complexity is increased not only by variations =
in kiln design but by differing fuels and atmospheric conditions.
I am sure you would never commence a firing using wet wood. I am equally =
sure you know the best time to introduce that resource in your firing =
program.
Best regards,
Ivor
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