Vince Pitelka on mon 25 aug 97
As requested by Joyce, here is a brief description of my bonfiring process.
It is loosely based on the system used by many of the Southwest Native
Americans, although I would not presume to teach that aesthetic, other than
a profound appreciation and respect for it.
I usually do starved blackware firings, because the change in the wares is
so dramatic. The wares are placed in a welded re-bar "cage," made of 5/8"
or preferably 3/4" rebar. The cage as I have made them is 24" square with
walls 12" high. The bars in the bottom and sides of the cage should be
spaced on four-inch centers. The cage stands on 10" legs, each made of two
or three lengths of rebar welded side-by-side for additional strength.
If you have a handy pile of several cubic yards or soil, ashes, or sand,
just dig a hollow in it, open in the front and at least ten inches larger on
three sides than the cage. If you do not have such a pile of material, dig
a big pit about 20" deep in soft earth or sand, at least ten inches larger
than the cage on all sides, with at least three or four feet of space
extending out in front of the cage. In other words, like a shallow grave
for two coffins. Sorry to be so morbid, but the allusion works.
If the earth is very soft, set the cage on scraps of steel plate or kiln
shelf. Or, if you anticipate this problem, weld flat feet on the bottom of
the legs.
In use, line the bottom and sides of the cage with sheet-steel scraps. MAKE
SURE THEY ARE SHEET STEEL AND NOT BRASS, COPPER, OR ALUMINUM. A good source
is #10 cans, such as restaurants receive canned food in. Cut out the tops
and bottoms with a can opener, and cut up one side with shears. If you use
many small scraps, such as the above-mentioned cans, you do not need to
drill holes in them. If you are using large pieces of sheet metal, drill
quarter-inch holes every three or four inches.
After placing the sheet metal lining in the cage, place in a newspaper
lining, and begin placing the pots. Wrap small pieces in newspaper and put
them inside larger pots. Place all pots face down, except in the event of
vessels where the top or rim is small or fragile. Place newspaper between
each piece. Even after the newspaper burns, it leaves a small cushion of
carbon between the pots, reducing marring from shifting during the firing.
Place small pots between larger ones, and avoid any placement where a pot
will wedge between others as the firing settles. The pots can be piled up
quite high. After they are all in place, cover them with newspaper and then
sheet metal scraps. Don't worry about small gaps in the sheet metal covering.
The following firing description is for wares which have been given a low
^018 bisque immediately before firing. With such a pre-bisque, you can use
almost any claybody (my favorite is equal parts fire clay, ball clay,
stoneware clay, and fine grog), and you will have little or no breakage even
in a very fast bonfire. If you do not want to do a pre-bisque, use at least
50% tempering materials (sand, grog, crushed seashell, volcanic ash, etc) in
the claybody, and fire VERY SLOWLY.
Assuming that the wares have been pre-bisqued directly before the bonfiring,
kindle a small fire beneath the cage, and keep it going for 45 minutes or
so, adding wood selectively to get the flames to lick up all four sides of
the cage. Use wood split quite small, and DO NOT ALLOW A COAL BED TO BUILD
UP. After preheating for 45 minutes or so, start to lean the wood
"teepee-style" around the cage, and gently lay small pieces of wood on top
of the cage. Build up the fire quickly at this point, until it completely
encompasses the cage. Keep it going for ten minutes or so, then let it die
down for a few minutes. Rake away any unburnt wood and large coals, and
dump a large trash barrel full of well-pulverized (run it through a garden
shredder if you have one) manure/sawdust mix (sheep, goat, horse, cow - in
other words, HERBIVORE!!!) on top of and around the cage, making sure to
push plenty of mix under the cage, and shovel some into any openings in the
top of the cage. Immediately bury the entire cage and manure in sand, soil,
or ashes, so that there are ABSOLUTELY NO smoke leaks. I cannot over
emphasize the importance of this if you want a true blackware firing. If
smoke is getting out, oxygen is getting in. Check the pile a few times over
the next hour or so, because it will settle a bit, and smoke vents may open
up. Cover them immediately.
Let the pile cool a minimum of three hours, and preferably four or five.
After the appropriate wait, dig soil away from around the cage so that it
falls away freely from the cage, making sure not to let your shovels EVER
touch the cage. Once the soil had been removed to the bottom of the cage
walls, carefully brush remaining soil and ashes away from the top of the
cage, remove the sheet metal, and starting picking out the pots. In
removing the sheet metal and the pots, be extremely careful to never let
sheet metal scrape any pots, or pots scrape against one another, as they are
quite vulnerable with a burnished or terra sig finish.
If you allow a coal bed to develop, and build a very hot fire, you will burn
off your burnishing and terra sig at the bottom of the cage, but will still
have beautiful blacks at the top. If you do not allow a coal bed to
develop, and keep the fire from raging too hot and too long, you will have
intense jet blacks at the bottom of the cage, and some color (depending on
slip or clay colors) showing through the black at the top of the cage.
Good luck.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
1560 Craft Center Drive, Smithville TN 37166
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