mel jacobson on tue 4 jan 11
lee has it correct.
often when firing, over use of fuel will stall
the kiln. (thee most common problem in firing.)
a kiln is not a car, you cannot just press down on
the foot feed and get more power.
i have shown many potters how to un-stall a kiln.
turn down the gas. open the damper a bit.
(and most fight me like cats, `mel, it won't work.`)
our wood fired kiln at the farm just keeps going all the
time, and never stalls. and why?
we only load about 5 sticks at a time, and just keep
doing it. we stir the fire box and have great air intakes
in the kiln.
we also back end stoke with very thin pieces of wood.
1x1 inch, 20 inches long.
one at a time.
as the kiln gets hotter, we are careful never to pile
in wood...never. we hold it back in fact.
donovan palmquist has designed a great wood fired
kiln, and has taught folks how to fire it.
it is flat, all the way back. it has a brick stacked grate
that holds the burning wood up over the air ports.
it has a great/perfect draw stack. one brick passive
damper, and a huge kiln shelf damper to control air.
the last time zak fired alone, he had two ice cream
pails of ash...and that was it. two pails. this kiln
holds about 250 pots. it is not a baby kiln.
our problem with this kiln is that it fires too fast.
yes, too fast. we have to hold it back. but, we
fuss over the wood, split it into small-ish pieces and
never use green wood.
it goes back to the newer theories of firing any fuel
kiln. you fire with maximum heat in the early stages.
fuel on full. as the kiln develops energy, you back
off the fuel. in many cases your fuel will be at almost
zero at the end, and the cones just drop like stones.
(this assumes you have a small flue. not 120 inches.)
as you back off the fuel you add oxygen. the heat
goes up. near the end of any firing you sure do not
have to have a kiln in full reduction. back it off.
most potters fire with far too much black smoke reduction.
it does nothing. pollutes, waste of fuel and makes
crappy pots. 1920's ideas.
now we fire with bright blue flame, full of oxygen.
low reduction.
and, hope against hope, we may fire in neutral.
color, what a concept.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
alternate: melpots7575@gmail.com
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