iandol on tue 11 nov 03
Dear Friends,
Mel's comment about commercial kilns shows us that we have to be aware =
of changes which come about, driven by industrial advances.
Little though I know about kiln design, if you are using a series of gas =
burners which feed a relatively small kiln via holes in the floor then =
you are not going to need bag walls. The whole heating concept is =
different. Rather than being based on transmission of heat via contact =
of hot gas on the clay thorough conduction, heating is based on =
radiation from the hot wall surface which surrounds the laden volume. =
Flames which rise up as a curtain heat the surface of the interior walls =
of the kiln and they radiate heat into the kiln.
There are new materials and systems out in the big world of ceramics =
that we as artists know little about and Kiln Technology is one we =
should come to terms with, be willing to explore and exploit.
Best regards to all,
Ivor Lewis. Redhill, South Australia
Hank Murrow on wed 12 nov 03
On Nov 10, 2003, at 10:54 PM, iandol wrote:
> Dear Friends,
> Mel's comment about commercial kilns shows us that we have to be aware
> of changes which come about, driven by industrial advances.
> Little though I know about kiln design, if you are using a series of
> gas burners which feed a relatively small kiln via holes in the floor
> then you are not going to need bag walls. The whole heating concept is
> different. Rather than being based on transmission of heat via contact
> of hot gas on the clay thorough conduction, heating is based on
> radiation from the hot wall surface which surrounds the laden volume.
> Flames which rise up as a curtain heat the surface of the interior
> walls of the kiln and they radiate heat into the kiln.
> There are new materials and systems out in the big world of ceramics
> that we as artists know little about and Kiln Technology is one we
> should come to terms with, be willing to explore and exploit.
Dear Ivor and kiln aficionados;
You have nailed an important distinction here. In the case of my
Doorless Fiberkiln, 16 very small flame retention tips enter the kiln
from below, angled out to strike the fiber wall first, creating a
virtual wall of flame. Flame is interesting if you can watch it work.
Flame follows whatever surface it first strikes, much like water. I
have poked a hollow quartz tube into the bottom of my design to see
what happens. The flame comes into the chamber and just fans out along
the wall as it moves upwards. So the wares in this case are not struck
by flame, and the 16 tips produce the wall of flame effect inside the
kiln. From red heat onwards, the kiln is operating in the radiant mode,
with the white fiber walls acting like a house of mirrors to reflect
onto the pots. The result is very even cones all around the chamber,
and a gentle heating of the wares. It should be pointed out that this
design is natural draft, not a pressurized situation, as in the various
flattop designs. They have their own sweet way of working.
Cheers, Hank
See it here: www.murrow.biz/hank/kiln-and-tools.htm
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