Jeff Lawrence on sun 14 dec 97
Hello y'all
First, here's my working definition of a bag wall:
an adjustable sack of masonry containing a time-slice of flame.
Now, my problem: I am unable to think like a flame.
I imagine that if I build a bagwall just so, the heat will disperse evenly
without burning pots on contact. My kiln is a gas-fired car kiln with two
forced-air burners that seems to need a bagwall. When fire it with no
bagwall, I get differences of up to two cones, and a lot of grayish pots
where the flame gets at them.
Each time I fire, I try to figure out where the heat is going and not going.
Then monkey with the bagwall to re-route the heat. Thus I have arrived at
the masonry equivalent of standing on my head while rubbing my belly and
whistling dixie. I've built little ramps to bounce flame up and upright
flame splitters to bounce flame sideways. I've got skinny cracks to cool
areas down and fat cracks to warm them up. I've even set up little venturis
by alternating fat and thin bricks, on the theory that more turbulence is
better turbulence.
Am I deluding myself that there is a perfect bagwall? Or am I too far gone
down a road whence the sane never return?
Thanks in advance for any suggestions, comments or better definitions.
Jeff
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt 3 Box 220
Espanola, NM 87532
ph 505-753-5913
fax 505-753-8074
Owen Rye on mon 15 dec 97
> From: Jeff Lawrence
> Subject: Bagwallowing - whither the flame
> ----------------------------Original message----------------------------
> Hello y'all
>
> First, here's my working definition of a bag wall:
>
> an adjustable sack of masonry containing a time-slice of flame.
>
> Am I deluding myself that there is a perfect bagwall? Or am I too far gone
> down a road whence the sane never return?
> Jeff Lawrence
Here's my definition of a good bagwall, if one is required to
distribute heat in a particular way: a row of pots or claywork which
aesthetically requires extreme kiln treatment. Never did see the
sense of putting the best surfaces on bricks, unless you want to
build yourself a pretty garden wall; no-one will buy them.
Perfect? interesting topic for a discussion.....
Owen Rye
Owen.Rye@Arts.Monash.Edu.Au
Ron Roy on mon 15 dec 97
Hi Jeff,
Well I may be deluded but I think there is - I found the process enjoyable
- lots of opportunity to use imagination and apply some science - flame
takes the path of least resistance - having an adjustable flue is a big
help.
You said you had a difference of two cones when you started - whats the
difference now?
>Am I deluding myself that there is a perfect bagwall? Or am I too far gone
>down a road whence the sane never return?
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Craig Martell on tue 16 dec 97
Hi Jeff:
I would have written sooner but I just now woke up.
I think we have the same kind of kiln and burner setup. Do you have a split
firebrick set at a 45 degree angle against the front wall where the flame
impacts? That really helps to pitch the flame up to the kiln roof. I have
a 13.5 inch high bag wall with about 2 to 2.5 inch gaps between the bricks
to let some heat through. At the front of the kiln where the flame hits and
things get real hot, I've added an extra 4.5 inches for a total of 18 inches
in height and this extends back about 14 inches or one 9" straight and one
half brick, with a small gap between the two.
I get real even firings to cone 10 with good even reduction.
hope this helps, Craig Martell-Oregon
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