mel jacobson on thu 17 feb 11
i have very mixed feelings about this.
it can be a project that ends in frustration.
we are very excited about the gas/electric conversion.
using a good electric kiln to start and fire the kiln, then
add gas for the final reduction phase. (that plan is in pmi.
or ask me to send you the directions. i am happy to do that.)
there is far more control of the firing. and, you can really
get cone 10 with lite reduction effects easily.
the thin walls of the electric kiln box is pretty weak. no k factor at all,
for a gas fired high temp kiln.
if one where to ask me, i would say..`don't screw with it`. do a real
kiln. half way never makes sense to me. elec kilns make great raku
kilns...but pig wire and kaowool makes a better one. far more efficient.
if you have the space, and no fear of firing...a small flat top
would serve anyone well. it can be placed under a metal roof,
have a bbq look, and if you do not pump out smoke, no one will
ever know you have it. we have at least four examples in our book
of very tight urban kilns. i mean, right on the lot line. not a problem
in the world. in our video we show kerry brook's kiln, in an alley, houses
all around,
with a nice wooden screen between her 70 year old neighbors
garden. three feet away. the woman has no idea there is a kiln
that close. kerry has made everything very clean, neat and well made;
it is a big donovan palmquist car kiln. she fires almost every other day.
commercial quality work. no one knows what she does behind that fence.
quiet as a mouse. compressed air blowers, no smoke. lawn mowers
make far more noise and fumes.
it takes a couple of days to build it. (used bricks are great
if you can get them, in fact a combination of many sorts of
bricks makes for a pretty nice looking kiln. and you have a real kiln that
will serve you for many years, and it will pay for itself in just a
year. if you need it...i can even send you a plan. and, we have
run this plan in pmi magazine to make sure people had access to
the information. it can be made literally any size.
it is the classic nils lou kiln design, but made very small...or any size
for that matter. we are using a kiln that kurt wild built in his studio as=
the
exemplar.
you know, that 24 cubic kiln size...+ or - (50 pot firing sort of kiln.)
this is not about arch/vs flat. it is about cost, ease of construction
and simplicity. we have built the kiln with almost no welding, using
thin aircraft cable and turnbuckles to hold the kiln together. everything
comes from the hardware store. pre/threaded rod, and a couple of
pieces of angle iron welded and drilled. it takes four/nine inch welds for
a small kiln. (any local welder will do it in half hour..often they do
it for a few bucks. tiny job.)
a piece of spiral pipe, some flue liners and you have a kiln.
you can even make your own burners if you wish. we have fired this
kiln with old throw away burners, weed burners, and those great
nils lou burners. it does not matter much. they all work. heat in,
hold it in, done. (our farm, tiny flattop fires in under 5 hours. no smoke=
,
propane, soft reduction. i put three pix of pots fired in that kiln on my
clayart page. above pix of bill's kiln.)
bill burgert's kiln in denver is right in the heart of old denver, a mile
from denver university. tight houses, small lots. we built the kiln
off the back of his garage, and ran a gas line through the garage from
the house. not a great deal of power, but enough...he fires cone 6
reduction. we even made our own burners. i will put a pix on my
clayart page of his kiln. neighbor houses all around him.
many think he has a food smoker/bbq. it is clean, neat, and no
trash. nice steel roof shed. it just works, and he has paid for that
kiln twelve times with home sales of his basic line of pottery. functional
items.
bill is a wonderful, open. helpful neighbor, he gives his pots to friends
near him. they all support his art. it is the key to having an urban
kiln. cooperation, helpful potter in the area. all want a piece of that.
pump black smoke just once...and you will have the fire department at
your door in twenty minutes. `sorry, take that kiln down right now.`
red tag on your gas meter. being classy, helpful, and have folks
understand you are a quality artist leads to great urban kiln success.
mel
bob anderson has the identical kiln in his backyard in antigo wisconsin.
folks around him love his kiln. a guy, just like bill.
my kiln has been in my studio for 45 years. no one sees it, or knows
i am firing. but, i can fix my neighbors furnace when it goes out at
-25F. i can weld the kids bike yolk. i can fix anyone's computer.
do they worry about my studio..??? not a bit.
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
Michael Wendt on thu 17 feb 11
A low "K" value for an insulating material is
desirable.
The "K" value is the measure of thermal
conductivity.
Its reciprocal ( 1/K), the "R" value, is the one
we see the most in things like building
insulation.
A very clear article which also gives an
overview of how ASTM measures these
values is found at:
http://www.diamondliners.com/articles/58,1.html
Making a round kiln a downdraft would be very difficult and
really serves no purpose.
Round updrafts can be fired perfectly evenly just by
using a sliding damper brick set at the top port
and observing a dual probe pyrometer with one
probe at the top and the other at the bottom.
I can fire the top of my kiln hotter than the bottom
by setting the damper a little too wide (1/16" - 1/8")
and I can make the bottom hotter than the top by
setting the damper a little too tight (1/16" - 1/8").
That's how touchy they are and why using a single probe
thermocouple is so tough.
Regards,
Michael Wendt
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