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fossil fuel fiber kiln - long

updated wed 30 apr 97

 

Samantha Tomich on wed 9 apr 97

Please forward comments to me on whether "they" think it will work. I
asked and got almost no reply. So I built it anyway, almost finished
actually. I was planning to go low fire only in this, but I'm now
contemplating firing higher and was wondering about the fiber idea and
ITC coatings and such things. The only reply I got was that the
materials sounded good. Here is that reply:

Hi Sam. Your proposed mixture sounds good to me. If you can get a bit of
cheap castable to add (from any refractory supply house-sometimes they
have a broken bag). We used to make bricks that way, fireclay, lots of
sawdust or vermiculite, all the scrap clay from recylcing bins, some
sand.
For a cone 10 woodfire kiln.
Sometimes I add a bit of cement fondu to make it all stick together
better .

ELKE BLODGETT email:
eiblodge@freenet.edmonton.ab.ca
12 Grantham Place
St. Albert, AB T8N 0W8
403 (458-3445); 403 (727-2395)
---------------------------------------------------------------------
I will post on Clayart sometime soon as to how this kiln fires. I just
have to add a little more clay, and soon it will be operational.

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These are the two messages I posted:
----------------------------------------------------
In Leon Nigrosh's book on low-fire stuff there are directions for
making a fireclay kiln. I have questions about changing the size of
it and the ingredients to make it.
It is made with equal parts fireclay and straw, totalling 150
lbs. I
was reading the posts on clay bodies for kiln posts and saggars and I
was wondering if I could use Fireclay, XXSaggar Clay, grog, sand,
vermiculite, dried cut grass, ...what if I put in paper mush?

I have 100lbs of goldart fireclay, 50lbs of red imco grog, 20
lbs of
xxsaggar, as much sand as I can carry, and lots of vermiculite and cut
grass. If I threw this all into the pot would this be a good idea or a
total bust?

You dig a trench a foot wide by 8 foot long. In the center dig a
circle
18"wide by 4"deep. Make a slab from the fireclay mix 16" in diameter
and put coils on it. This goes on the hole. Put stovepipes on the side
trenches as a form for the fireboxes and cover each with a sheet of
plastic then 2-3" of the fireclay mixture. Coil build a firing
chamber/stack with the fireclay mixture, 2-3" coils, widemouth bottle
shape 30"tall. When stiffened, pull out the stovepipes.

You're supposed to fill the chamber halfway, but that's so
small, if I
change the size of the chamber, am I going to ruin it? Would I have to
compensate with the height of the stack or something?

I really like the idea here of a semi-permanent pit-fire site that looks
primitive, no trash can etc, and it seems to be what I've been looking
for. Can anyone tell me if these changes spell disaster? Your help
would be very much appreciated!

Also what effect would salt have on this kiln. I am thinking of
throwing sawdust and combustibles in the chamber to get blackware and
putting in lidded pots as saggars containing smaller pots with different
combustibles, and surface treatments. The author says it is *possible*
to reach temps *near* ^02.
He feeds wood into the fireboxes slowly until the flames are leaping out
the top of the chamber, continues for an hour, then lets it go out. I
think this would make a good wood fired raku kiln if you put a pyrometer
on it. Am I right?

Thanks so much, Sam
--------------------------------------------------------------
Hello, Eric, and all you clayarters,

I am building a kiln sometime next week using plans in Leon Nigrosh's
book Low-Fire-Other Ways in Clay. This kiln has the shape of an
upside-down T with the two side chambers on the bottom as fire boxes and
a beehive type center. I am using a mixture of gold art fire clay 100
lbs, xxsaggar 20 lbs, red imco grog 50 lbs, vermiculite 24 dry gallons,
very course sand 5 gallon bucket full, coarse sand 5 gallon bucket full,
and dried grass clippings and crushed dry leaves, & maybe I'll throw in
some paper clay. Got this mixture slaked and drying on cloth covered
boards downstairs.

My questions are:

Eric, could you also fax me the design of the kilns they are building
there?

For clayarters in general: what purpose would the shards have in
firing? Where do you put them? I have access to a lot of small
unglazed terracotta flower pots. I would like to use this kiln to fire
pit-fire/ sawdust type of firings. I would place the pots in the center
chamber and surround with sawdust and lay shards to hold the stuff (and
heat) in place. What do you think? too much fire, right? so if I just
use the center part for that type of firing and then pile sticks and
like that on top of the pile, would that be the ticket or still too
much fire?

Does a sawdust firing need less air and fire so that it smothers along?
Can I achieve this by covering with shards?

And, if I sawdust fire, do smoke marks cover designs painted on with
slip? I want some totally black, and I was going to do the terra sig
stuff Vince posted, and other pieces with some color and smoke effects
by wrapping with seaweed and banana peels and throwing on some chems. I
can just throw all this stuff in together? Do I need to make saggars to
put pots in for different effects?

I would also use this as a raku kiln in which I would place a larger
piece in the center and then fire up the side chambers, slowly at first
(I plan to bisque all the pieces first) until it's jammin'. How do I
tell when it's done? What does the glaze surface need to look like when
it's ready for you to pull it out?
The book says they've fired up to ^02.

Eric, do the potters there have any sort of a chimney, or do the sides
go straight up?

Clayarters: Do I need a chimney, or can the sides go straight up (much
better for me to raku)? Can I make a cover with the same clay mixture I
am using for the kiln? The book mentions to keep the fire steady or you
lose the draw... Am I going to make something unfireable because of the
"draw" aspect if I change the kiln shape, size, height, etc? The shape
used in the book is a beehive with the top in a sort of short open
chimney shape with no cover. I want straight sides with a removable
cover, with some hole (size?) as a damper that I can cover, partly
cover, or leave open by covering with more of the same material I am
building the kiln out of.... Will this work? Any better Ideas?

Also, since I don't need this mixture to be very plastic (right? because
I'm not throwing it or anything) can I load in more sand? How much
non-shrinking stuff and opening of the clay body would be too much?

I'll be back with more questions soon! Thanks to anyone who takes the
time to read this and reply. I have posted questions about this before
and got one answer on the materials and went for it. If I get anything
on this - wonderful, if not I'm going to go for it and post my
results.... I hope it's good, I am building it with friends for my
birthday. We are going to fire it up and party, and it would be a
bummer if the whole idea sucked and I wasted all that clay.

Thanks, Sam
------------------------------------------------------
I made the hole deeper and I'm not sure how that will affect the firing,
I thought I would try porous lava rocks in the pit to help hold the heat
in...(that's what they do for a luau to cook the food) Who knows, this
may all be a bust, but I have a nice yard decoration, and I found out I
like working in coils on huge pots.

Samantha in Hawaii

Sylvia See on thu 10 apr 97

Hi Samantha;
I will be one of those anxiously awaiting the results of your first
firing. I appreciated your last message with all the information of what
your are trying to do and the materials you are using.
I am behind you stealing your ideas like mad and applying them to the kiln
I am in the process of making. I have everyone looking at me like I'm nuts,
but I'm plugging away with it. It can only have 2 results, either it will
work or it won't. I am trying to make a downdraft, beehive shaped reduction
or salt kiln, and I want the dome portable, so that I just have to setup
the base when I want to use it. I am making the base and chimney out of
firebricks, but that is all I can afford at the time. So I am making a
paper mache mold over which I am going to apply coils of Cone 10 Raku
clay.I'm cutting the dome in half so that I can assemble one half, load the
pots or castles, and then setup the second half and strap together.I wanted
to line the inside of the dome with fiber, but was pretty worried how it
would stay on the shell. Thought about making the paper mache mold as thick
as the fiber, and then making a second shell on the inside of the mold.
After burning out the paper mache, putting the fiber on the outside of
smaller shell and then sliding the outter shell on the outside. I wouldn't
have to worry about the fiber that way as it would be between the two
shells. However, my main concern is firing the outer shell with the paper
mache the first time. It will have to be outside and all the heat in the
inside of the shell. I have visions of quite and explosion if it blew up on
me. I really thought the only way was to wrap the fiber on the outside of
the shell for the first firing. may still do this. However, I knew nothing
about the fireclay, sagger clay, sand, vermiculate, etc you mentioned. Now,
I feel a little more confident. Been reading on these and I am now going to
wedge them into my raku clay and then run it through my pugmill several
times to make sure it is well mixed. I think I will also trowel on a
mixture of fireclay, saggar clay, vermiculate and sodium silicate over the
clay for the outer shell. It should help it from being directly exposed to
the air when firing it the first time and help to get it to a higher
maturing temperature. Then use the same mixture and trowel over the fiber
on the inside of the kiln, eliminating the need for the second smaller
shell. I have alot of folks shaking their heads, but Lordy if it works,
you'll hear me all the way in Hawaii.
Wishing you lots of luck and guts, and a Happy First-firing
Also going for it in Claresholm, Alberta Sylvia See
The golden years have come at last, I cannot see, I cannot pee,
I cannot chew, I cannot screw. My memory shrinks, my hearing stinks.
No sense of smell, I look like hell. My body drooping, got trouble pooping.
The golden years have come at last, The golden years can kiss my Ass.