mel jacobson on wed 1 dec 99
have been thinking a great deal about the history of my firing
schedule....it is long. almost 40 years in this house with the
same kind of kiln. same gas pipe, same burners. the bricks have
been changed around, configured differently now and again, but
basically the same kiln.
the more i dwell on it, the more i feel that i am trapped in a system
based on gas pressure, stack, flu and weather.
i could probably take an hour out of my firings, but rather think it would
do little to improve things.
most of my firings last about 10 hours...it just sorta takes that long.
i start my kiln about 4 a.m. like the quiet time, alone time with the
kiln. i only have about a pound of gas pressure, it is low and slow.
use the old denver burners i got in 1960. big lazy, very nice burners.
i ran my own gas line from the house, just used a hack saw and cut
the pipe, put in a T and went through the concrete block...has worked
just great.
because of the lack of intense gas pressure the kiln just sorta fires itself.
i hold back some gas for the final push, sorta need it for cone 11.
so much of my firing schedule is based on what the kiln is, how it fires
depends on weather, wind, high and low pressure.
i chuckle when i hear tony talking about me firing fast.
it is a grandpa speed kiln, but fires even, 4 cone pats going over
together.
and makes good pots.
i cool slow, re/light at 1700 for about 15 minutes.
crack the door at 500f.
take out pots the next afternoon.
(of course i have been known to melt plastic flashlights peeking in the kiln.)
in so many ways, i think i stumbled on a good system years ago.
long before i had any real knowledge of the science of firing, oxyprobes,
etc. lucky.
i have teased nils for years that i had the very first double venturi
exit flu.
i just did not know how, or have any brick that would span two bricks.
so, just went with a flu exit about 38 square inches.
it seems to be just right.
the kiln fired to cone 10 in nine hours, the first time i fired it.
it has worked basically the same for 40 years.
when i built that first ifb kiln, i had never seen one, only a plan
by a guy from iowa named mckinnell. he changed my life.
i think ron roy built his first kiln about the same time that i was
building mine...he still fires his the same way, same speed.
i have fired many other kilns....most with very high, near 10 pounds
of pressure and find they almost always have their own minds.
i try to get folks to cut the pressure, slow things down a bit.
flame spewing from every port....roaring fire. one has to be careful
about burning your face off to see the cones.
i think many folks out there have mis/interpreted nils' argument.
he fires under a great deal of control, understands kilns as well
as anyone on this earth....
what he tells us is; you do not have to baby the kiln for hour after
hour in the early stages.
why candle for hours and start real slow...you know, hardly any flame.
6 hours to cone 012.
he just starts the kiln, full gas, gets the thing going.
then the kiln evens out and gets rolling.
he can easily cut hours off a firing and still do it perfectly.
and he can prove that all the didddling around in the early stages
is just that....didddling around.
and i believe that, trust that.
many commercial ceramic engineers will confirm that.
but, we are creatures of our habits, our art...and we
are not commercial engineers...we do things alone.
we do things our way. we have no alternative,
it takes years for old tales to clear from our heads.
so, i do not know what is best for any of you.
find a schedule that works.
nils will tell you over and over...most flu's are too big.
gas wasters.
stacks are often the wrong size, add or take off three feet.
many people fire with too much gas, just over power it.
firing is about finding balance....sorta like throwing, you
find rhythm. then make it work.
fear is still the big enemy, far too many people are frightened
of their kiln.
get over it. there are pots to fire.
do it.
mel/mn
i am not speaking for nils, just giving you what is in his book.
read it, and olson. and listen to marc ward.
they know what they are talking about.
http://www.pclink.com/melpots
from minnetonka, minnesota, u.s.a.
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