mel jacobson on mon 21 feb 05
it always astounds me how well the double venturi
system of a nils lou kiln works. i am not debating
the flat top/arch concept. (don't want dr. mcgill on
my case.)
anyway.
i fired yesterday, oxidized all the way, and as i said
yesterday, i took out the damper, plugged the damper slot
with kaowool and fired at 3/4 gas pressure for the
entire firing. did not touch anything, make any adjustments
for the entire day.
i have household gas pressure/ about one inch of
water column. about 40 feet of gas pipe (inch and a half)
from the house to the studio. the gas company and some
others have said this cannot work. not enough gas volumn or
pressure.
it works.
and, of course, it fires reduction just as well.
i know my kiln will fire beyond cone 15.
it never stalls. i am sure it is due to the
small 37 square inch double venturi flu.
as i have joked about before, my first kiln in 1965
had a 37 square inch flu opening...as i did not know
how to make it any bigger with the brick i had.
it worked great. (of course nils copied my kiln :))
i have worked with six different potters this year on
getting their kilns to quit stalling and fire in a more modest
10 hours, rather than 16-20.
in all cases, we turned down the gas pressure, added some
brick to their flu system...and generally backed off the
power. in every case, this has worked. and, it does
not surprise me in the least. we save gas/time/energy.
we let the kiln and oxygen do the job.
i have seen several kilns this year with 100 inch flu
openings. they don't work. they heat the atmosphere.
they never get past cone 5. yet they are fired over and
over to see if they can get to cone 10. stupid.
if you are using compressed air/blowers and tend to get
them on too strong...i think a small flu could be a bit
dangerous. too much gas and air could cause trouble.
nils feels that this size is perfect for compressed air kilns,
and he would tell us all to understand how the amount of gas
and air pushed into a kiln should be controlled....as it
is how a kiln fires....if you over power your kiln with gas
and air you are looking for trouble with any kiln. common
sense should dictate this. but, we are in the business of
protecting every idiot in the world...buy a toaster that
makes toast?...cannot be found.
anyway.
this is important stuff. it cannot be talked about too much
or debated too much.
far too much old technology, based on bad science running
amok out there.
i will predict that the next generation of kilns built for
studio and home use will be softbrick, with kaowool blanket
laminated to the interior. itc or equivalent will be sprayed on
top. industry is using fiber. it is the best of all worlds
for modern kilns. the problem is: it is not safe for your lungs.
so, spray it with itc.
encapsulated.
mel
From:
Minnetonka, Minnesota, U.S.A.
web site: my.pclink.com/~melpots
or try: http://www.pclink.com/melpots
new/ http://www.rid-a-tick.com
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