Bruce Bowers on fri 24 sep 10
Hi Folks,
I am going to be doing a wood firing in about a week and have been thinking
a lot about some problems I have had in the past with reduction cooling.
I only use 1 glaze, as an occasional liner, and it is good from C/6 -
C/14....so no problems there.
I use indigenous clays with a bit of feldspar and Newman Red added, and it
flashes and takes ash very well.
Flashing diminishes over about cone 10 and is actually at its peak near the
cooler (like C/8) parts of the kiln.
My problems come with reduction cooling. When at its best, it gives me
some nice, gray to black reduced iron areas combined with reds and ochres,
etc.
At its worst, the pots are too dark and sometimes have spikey, unmelted ash
on them.
I have heard that using cordwood sized pieces, hardwood 100% charcoal, or
kindling during cooling is best. So many conflicting ideas!
I always seal up the kiln cracks, air intakes, etc. before a final heavy
reduction stoke and then leave the damper open a bit and stoke as needed to
maintain a fluctuation between oxidation and reduction. I let the kiln
clear completely after each light stoke.
Could anyone please give me any advice for more consistency and
clarification on any of the above points.
I don't want to screw up this load.
Thanks,
Bruce Bowers
_www.bowerswoodfireandpics.com_ (http://www.bowerswoodfireandpics.com)
Lee Love on fri 24 sep 10
On Fri, Sep 24, 2010 at 8:22 AM, Bruce Bowers wrote:
> My problems come with reduction cooling. =3DA0When at its best, it gives =
=3D
=3DA0me
> some nice, gray to black reduced iron areas combined with reds and ochres=
=3D
,
> etc.
Bruce, I have best color response when I crash cool at the end of
the firing to 1100*C. You get the red from minute amounts of iron
and high alumina. Cool down reduction makes dark crusty pots,
especially in high iron clay bodies.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
tony clennell on sat 25 sep 10
Bruce: My MFA thesis show was reduction cooled work so was that of two
of my fellow grad students Heidi Kreitchet and Trevor Dunn. We did a
lot of work on developing a crusty surface. We found that Cone 8 with
maybe a cool 9 was best for reduction cool. This would sinter the ash
but not melt it. Our motto there is only one colour worse than brown
and that is shiny brown.
We also found that copius amounts of bark would create more surface.
We actually collected and cherished pallets full of cottonwood bark.
We held the kiln for as long as possible usually over 24 hours at
below Cone 9 to increase the amount of wood put thru the kiln. We then
would crash the kiln to1900F and clam up all cracks and crannies where
air could get in. The damper was left open just an arm pit hair so
that you could see a snakey flame when you stoke.
the piss off with reduction cool is you want the kiln to go down in
temp with a stoke but it often goes up. Each temperature rise is a
cuss word which is different from firing a normal wood firing where on
the way up a drop in temp brings on a cuss.
We fired down till 1300-1350F so as to not have the surface re-oxidize.
I must say you need a iron rich clay and the only glaze i found that
looked any good was temmoku which often came out looking like a rutile
blue.
I sprayed the bisque work before firing with laterite or crocus
martis. Both of these iron rich materials gave wonderful greens ,
yellows, greys and purples.
It meant the work came out of the kiln looking all dusty and dirty. A
power hosing, a wire brush and don't tell anyone but a coating of semi
matte Armoural would reveal these amazing colours so seldom seen on
the potters palette.
This process is double the work. Fire it up and then just when you're
already in the bag you have to stay up and fire down. This is not for
the weak of heart but colours not seen often.
Bon feu!
Tony
On Fri, Sep 24, 2010 at 9:22 AM, Bruce Bowers wrote:
> Hi Folks,
>
> I am going to be doing a wood firing in about a week and have been thinki=
=3D
ng
> =3DA0a lot about some problems I have had in the past with reduction cool=
in=3D
g.
> I only use 1 glaze, as an occasional liner, and it is good from C/6 -
> C/14....so no problems there.
> I use indigenous clays with a bit of feldspar and Newman Red added, and i=
=3D
t
> flashes and takes ash very well.
> Flashing diminishes over about cone 10 and is actually at its peak near t=
=3D
he
> =3DA0cooler (like C/8) parts of the kiln.
> My problems come with reduction cooling. =3DA0When at its best, it gives =
=3D
=3DA0me
> some nice, gray to black reduced iron areas combined with reds and ochres=
=3D
,
> etc.
> At its worst, the pots are too dark and sometimes have spikey, unmelted a=
=3D
sh
> =3DA0on them.
> I have heard that using cordwood sized pieces, hardwood 100% charcoal, or
> kindling during cooling is best. =3DA0So many conflicting ideas!
> I always seal up the kiln cracks, air intakes, etc. before a final heavy
> reduction stoke and then leave the damper open a bit and stoke as needed =
=3D
to
> maintain a fluctuation between oxidation and reduction. =3DA0I let the ki=
ln
> clear completely after each light stoke.
> Could anyone please give me any advice for more consistency and
> clarification on any of the above points.
> I don't want to screw up this load.
>
> Thanks,
> Bruce Bowers
> _www.bowerswoodfireandpics.com_ (http://www.bowerswoodfireandpics.com)
>
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