Jeff Tsai on thu 25 apr 02
Jeff Longtin wrote about doing fast firing with leather hard work (short
candles and fast firings)
I've heard of this from time to time, actually I've done this from time to
time. I recall that a studio mate and I were having a sale soon. He had some
already bisqued steins that he wanted to fire in the soda kiln for the sale,
but we'd need more work to fire the soda kiln and the soda kiln would've
needed to be loaded the within 36 hours or else there was no way the kiln
would fire off in time, so I went to work.
I threw a bunch of work that didn't need trimming and used a paint stripping
gun to dry it enough so I could lift them off the wheel with ease. I then
placed them into a candling electric skutt just after lifting them off the
wheel. It took a few hours of this to fill the skutt with enough work and I
was ready to fire.
I candled for two more hours, but I left the lid of the skutt completely
open
and put a big square floor fan over the top facing up and turned it on. BY
the time I put the lid down, the stuff was really quite dry. The constant
airflow caused by the fan really dried the work fast (it also helped that
the
clay was heavily grogged.)
I fired up in about 5-6 hours, unloaded 14 hours later and glazed the work.
It was an eye-opening experience and I got some flak from the professors for
doing it, but other than some s-cracks and two blowups, nothing much
happened.
IN other thoughts, I recall pete pinnell telling me that completely wet work
wrapped inside aluminum foil would survive a bisque ( I think it was foil).
I
can't reiterate what he said as well as he said it, but I think (and I
haven't tried this so I can't say it's true or not) he said that as the
piece
heated up and released steam into the atmosphere, pressure would slowly
build
up in the foil so that later, as steam tried to "explode" out, the pressure
from the steamed up environment would act as counter-pressure resistance.
I assume this is the same theory as Soldner's whole steam firing a bisque
concept where he puts buckets of water over the burners? It would be nice to
hear what others have to say about this....does it sound reasonable?
-jeff
Dave Finkelnburg on sat 27 apr 02
Jeff,
Fast drying wet ware works by raising the temperature and the humidity
surrounding the ware at the same time. When both are relatively high, then
the humidity can be lowered, and the moisture migrates out of the full clay
body fairly rapidly. The ware is still damp throughout, so the moisture
moves through the clay relatively well.
The secret is to not have the outside bone dry and the inside still wet.
That leads to blowups! :-( Ware that is bone dry outside is effectively
sealed against easy moisture migration from inside the ware. Heavy grog or
sand addition, of course, counters this.
Commercial drying cabinets are built to control humidity and temperature
both. Firing wet ware in a kiln is possible, as you have discovered. It is
less controlled!
Good potting,
Dave Finkelnburg, enjoying the garden flowers beside the pond in
Idaho
Michelle Lowe on mon 29 apr 02
At 02:38 AM 4/25/2002 -0400, you wrote:
>I assume this is the same theory as Soldner's whole steam firing a bisque
>concept where he puts buckets of water over the burners? It would be nice
to
>hear what others have to say about this....does it sound reasonable?
Randy Schmidt up at ASU does this type of "wet" bisque every now and then,
where they fire wet work, and hose the kiln down while firing . Very few
blowups, some cracks here and there, but generally fairly successful.
Mish
Michelle Lowe potter in the Phoenix desert
http://www.desertdragonpottery.com
Mishy@desertdragonpottery.com
mishlowe@amug.org
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