Rachel and Eric on thu 8 jul 99
Antoinette,
There's a village here in Oaxaca, Mexico where they haven't made
anything BUT black fired pottery for about fifteen centuries. Here's how
they do it, in brief. First, the pots are burnished, this is not a
necassary step, rather an asthetic one. Burnished blackfired pottery is
mighty pretty. Then to the kilns. The kilns here are simple updraft kilns,
fire box below, pottery chamber above. The two are separated by brick arches
that create a thick grill. These kilns are built dug into the earth so that
the tops, where they are loaded from, are flush with ground level. The
reason they are sunken like this is to facilitate the seal necassary for a
full reduction. These kilns have no lid, they are open topped. Once the
pottery is loaded in a "lid" is made by covering the top layer of pots with
pottery shards. These shards create a pourous seal which hold in heat but
lets the air and smoke from below travel through. These shards also keep the
mud that is later used to seal the kiln from falling in.
The kiln is fired up, slowly fed for about 10 hours. At a certain
point, when the pots look right, starting to glow a low red meaning they are
just about done, the fire is really stoked, stoked until flames from the
fire are shooting out through the top. Then the kiln is stuffed full of wood
and the potters begin to seal it off. The smoke really begins to stink at
this point, the acrid smell of oxygen hunger, reduction. This sealing is
done with wet mud. This is shoveled on top of the shards that were used to
cover the top opening. It is then spread evenly across them creating a seal.
At the same time, down below the fire box door is being bricked up. Once
bricked it is sealed over with mud too. Then a burning piece of sapwood is
run around the sealed door and top. Any leaks will be leaking volitile gases
and will ignite into a blue flame, showing themselves to the potter who
then covers them over. Once that process is through, the firing is done,
full reduction has been induced. The point it to COMPLETELY smother the
fire. Occasionaly there are leaks, gofer and ant holes that aren't
detected. This causes white spots on the otherwise black pottery. It is
considered defective by the potters. I find it quite attractive.
There are more details that go into the firing than this, the way
the wood is handled, the exact manner in which the openings are sealed up.
But they are details. The important thing is that the fire is completely
smothered, this is done ONCE the pottery has reached its maturing
temperature. The outcome is black pottery, often with silver sheen flashing.
This is low fire pottery, probably not hotter than 1300 or 1400 F.
though I haven't stuck a pyrometer in there yet. You can't get to hot or
you'll lose the burnish. The cooler it is, the smoother the burnish will
fire. Terra sig, which would facilitate burnishing, would be a fine finish
to put on.
And if you really want to learn this technique, come to the
Pre-Columbian Woodfire workshop I'm hosting in Oaxaca this winter. We'll be
firing these kilns and others.
Saludos, Eric Mindling
Date: Sat, 3 Jul 1999 09:37:46 EDT
From: Antoinette Badenhorst
Subject: Blackfiring
----------------------------Original message----------------------------
Hi again. I would also like to try out some blackfiring. I am not sure
how to tackle this. I believe that one must completely cut off the
oxygen to the pot, but how will I do that and don`t kill the fire?
Can anyone help with a slip , glaze or terra sig. that will help me
create a metallic black.
I have a specific design in mind and I am very frustrated with the
technical way of doing this.
Thanks again.
Antoinette
===
Antoinette Badenhorst
PO Box 552
Saltillo,Mississippi
38866
Telephone (601) 869-1651
timakia@yahoo.com
______________________________________________
Rachel Werling
and/or
Eric Mindling
Manos de Oaxaca
AP 1452
Oaxaca, Oax.
CP 68000
M E X I C O
http://www.foothill.net/~mindling
fax 011 52 (952) 1-4186
email: rayeric@antequera.com
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