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i need help with pit-fire, wood-burning, kiln idea

updated fri 28 feb 97


Sam Tomich on wed 26 feb 97

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