mel jacobson on sat 17 nov 01
there is a great deal of misconception about the history
and value of the minnesota flat top kiln. It is a marvelous
design, and is predicated on the idea of ease of construction,
simple technology, and can be built in any size.
nils developed the idea many years ago. the first ones i believe
came from the idea of jim mckinnell from iowa.
mckinnell created a flat top soft brick kiln using beams or
blocks of soldiered bricks held together with steel rod through
a hole drilled in the upper third of the brick. they were bolted
together with threaded rod, or a bolt welded to the end of the
rod. many used a stiff spring to aid the tightening, and give
the beam some room to expand.
these kilns worked well, but had a tendency to drop broken parts
of the roof onto the pots. the bricks would often split or crack
at the drill hole.
there was also a suspended roof system that was very good.
i think ron roy still has that kiln, and it works like magic.
burners were place all over the kiln...some had four, some two. it
was basically a down draft kiln with the burners placed wherever
the potter wished to put them. I had two burners on mine that
were opposed. the flames joined, went up and came back through
the ware, out the lower back.
i feel that the most important part of the flat top design, as we know it
today,
was the invention, by nils, of the corner brackets...made of two pieces of
angle iron/welded together. this simple, yet complex idea made it possible
to hold the entire roof together to create a monolithic soft arch. (it has
never
been flat.) the roof stands alone because the pressure on the soldiered brick
comes from the corners in. it is a perfect system. it is a small piece of
genius.
thank you nils...it changed the course of kiln construction in the world.
that
is what makes genius...not grades or i.q. change the world as we know it.
it does not minimize the use of arches in kilns. that was not the intent.
if you like arches, know how to make them....have the extra money for complex
welding...no one cares how you do it. that is not the point. there is an
alternative...that is the point. the alternative is simple...about half
the cost.
works.
when i built the kiln in denver last month, i was able to show them how to
build a kiln without any welding...(except the four small welds on the corner
brackets.) we used aircraft cable stretched around the kiln and connected
with turnbuckles. one can also drill holes in the angle iron and thread
through
eye bolts and stretch aircraft cable around, then tighten the eye bolts.
i found everything we needed for that kiln at home depot. (cage)
kurt and i have built many small, back yard mft's at very low cost.
they are the size that a part time potter can live with, use, and
does not cause a bankruptcy. the first five firings will pay for everything.
i have a forty cubic foot kiln, kurt has a twenty four, bob fritz has a
twenty four....
we have a twenty at the farm that is just perfect for firing a small load with
all experimental glazes.
the design for the nils mft car kiln is an entire different story... you must
be prepared to spend a great deal of money, have a good welder hired,
and above all, have a big space, flat and clear. covered. a car kiln is built
for a serious potter.
i built my first kiln without ever having seen a soft brick kiln. i just had
a set of plans from jim mckinnell. i did not know how to bridge the flue to
make it 81 inches...so i left it small...about 35 square inches...as it turned
out, it was the perfect size. it fired to cone 10 the first time i fired
it...10 hours.
it has done that for almost 40 years. same denver venturi burners, low gas
pressure, thousands of pots fired. i have rebuilt the kiln four times, but
the
burners and specs have remained the same.
the most important aspect of firing a kiln at home is safety. knowing how
things
are hooked up. never leave your kiln while firing. pay attention. don't go
to sleep. follow simple rules of safety.
building a kiln is a `right of passage` for a potter. it is not essential
to being
a fine potter, but it makes one complete.
like vince said this day, `broad range of knowledge`. what i say is:
`don't be a one note song`. be mozart.
mel
again, thanks nils for all you have done, for all of us.
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