Gerald O'SULLIVAN on tue 7 sep 99
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I have been playing around with very, very basic firing methods, using =
charcoal
instead of wood, and have had some very good results. The pots are made of
heavily-grogged earthenware, decorated with incisions and burnished and =
fired
raw (but bone-dry) in a bed of charcoal.
I built the kiln from house bricks, one cubic metre (we are metric in South
Africa, so that's 3 foot x 3 foot x 3 foot, near enough I guess), loosely =
piled
up, no mortar, lots of gaps, especially on the bottom (the base is a double
layer of bricks). Looks like a short stubby square chimney.
I make a small fire in the bottom of the kiln to get some red-hot coals, put
some in each pot to heat them while they stand to one side, then pour in a =
bag
or two of charcoal over the fire, and carefully (but quickly, before the =
fire
really gets going) place the pots around on the bed of charcoal. Now I pour =
a
couple more bags over the pots and cover the kiln with a sheet of corrugated
iron. It will smoke for a while, but when the fire gets going, it gets WHITE
hot. I use real charcoal - not those pellets of compressed coal-dust and =
flour.
If all goes well, the pots are a beautiful deep orange, with flashes of =
black.
If it goes less well, they are a boring beige - most likely a question of =
how
much reduction is happening around the pot. Losses are rare, because of the
pre-heating (I did have a problem with flaking off the exterior, but I had
burnished these pots after painting slip over them, so I stopped).
Now I want to move on to low-fire glazes fired in a Japanese charcoal-fired
kiln, having seen the diagrams in Leach's Potters Book, and also in Steven
Branfman's Raku book. Has anyone out there built anything like this? Or is
everybody into roaring venturi burners and kao-wool?
Are there any cautionary tales or words of wisdom from those who have =
trodden
this less-travelled path? What clay did you use for the saggar? How did you =
fire
it? What did the kiln lid look like - lots of holes or just one in the =
centre?
What did you use to make the kiln lid? Did you use test rings to check the =
melt
or could you peer into the saggar somehow? Do you need a saggar at all or =
does
the ash mess up the surface? Am I wasting my time? Should I start turning an=
oil
drum into a top-hat right now?
Candise Flippin on wed 8 sep 99
Hi all!
I was taught that the Japanese would build the kiln for each piece and
that it might take as long a 3 days to fire from green to completed.
I've only been able to manage the one piece at a time, but I do not
rebuild the kiln for each piece. And, yes I use a venturi burner with
soft brick.
Hope this helps, Candise in pleasant San Diego
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