John Anthony on sun 4 jan 04
I had remarked to a wood-fire friend that for awhile my favorite pieces
from the wood
kiln were the wads. Beautiful orange flashed little gems. They were
about half and half
by volume epk/alumina hydrate. I started checking out the alumina
containing shinos
of Jim Robinson and others, with very positive results in my
atmosphere. Also have a couple of
slips modified with alumina that look very promising. To really achieve
the same results
I guess I should just thin out the wad mix and spray it on a few pots.
Pretty dry I would imagine.
I put salt or salt/soda in my single chamber cat by making newspaper
burritos about 14" long and stoking one from each side
on a board, followed by a few sticks. I have been doing this starting
when there's a tip on nine, then again
when nine is down, and then again when ten is tip-touch. Each burrito
contains about two pounds. When I use soda
the total is about ten pounds salt and two pounds soda, evenly divided
among the burritos.
Next firing should see some interesting alumina tests.
John Anthony
http://www.redhillpottery.com
iandol on tue 6 jan 04
Dear Friends,
Posts about the delivery of the glazing agent into a kiln are =
interesting but to discuss firing effects without reference to time and =
temperate robs potential users of valuable information. Same as posting =
a glaze recipe without reference to cone, positive and negative ramp =
speeds, dwell times or the nature of the clay body.
Best regards,
Ivor Lewis. Redhill, South Australia
John Anthony on tue 6 jan 04
iandol wrote-
>>to discuss firing effects without reference to time and
>>temperate robs potential users of valuable information.
I had written
>>>starting
>>>when there's a tip on nine, then again
>>>when nine is down,and then again when ten is tip-touch
Guess I'm missing something.? Cones- that's time and temperature for
me.
cheers
John A
iandol on wed 7 jan 04
Dear John Anthony,=20
You give the following example..<then again when nine is down,and then again when ten is tip-touch>>..
Seems to be nothing to complain about
....except you are missing the two intervals which separate the three =
events. It is information which is not recorded. "Then again" may be a =
few minutes or an hour.
....Except the question of the effects of soda or Salt on Cones. As =
indicators of the work being done they are only consistent when their =
chemistry is constant. Additional salt or soda diffusing into the =
substance of the cone will cause it to collapse at a lower true =
temperature.
Best regards,
Ivor Lewis. Redhill, South Australia
Lee Love on thu 8 jan 04
iandol wrote:
>....Except the question of the effects of soda or Salt on Cones. As indicators of the work being done they are only consistent when their chemistry is constant. Additional salt or soda diffusing into the substance of the cone will cause it to collapse at a lower true temperature.
>
>
Because we are concerned with the surfaces of the clay bodies in the
firing, which are effected by the same conditions as the cones, the
cones are a more accurate indication actual state of the clay surfaces.
The actual pyrometer measurement may be irrelevant. Sometimes our
love gadgets and electronic measurement get in the way of knowing what
we really want to know.
What I come to appreciate from my teacher's way of firing, is
pulling test tiles. This was done for the noborigama, the gas kiln
and also for enamel firing. Test tiles or rings are the most
accurate measurement of the state of the glaze during the firing..
Lee In Mashiko, Japan
http://Mashiko.us
Web Log (click on recent date):
http://www.livejournal.com/users/togeika/calendar
Hendrix, Taylor J on thu 8 jan 04
Ivor:
If salting/soda introduction occurs near the endpoint of the claybody's
heat treatment, effect of vapor on the cone pack ain't all that. Right?
Is that how most vapor glazers do it? My notes are nonexistant on
salting--wrote too many pages on ASH!
Taylor, in Waco
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of iandol
Sent: Wednesday, January 07, 2004 12:37 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Salt delivery/alumina
...
....Except the question of the effects of soda or Salt on Cones. As
indicators of the work being done they are only consistent when their
chemistry is constant. Additional salt or soda diffusing into the
substance of the cone will cause it to collapse at a lower true
temperature.
...
Craig Martell on thu 8 jan 04
Taylor sez:
>If salting/soda introduction occurs near the endpoint of the claybody's
>heat treatment, effect of vapor on the cone pack ain't all that. Right?
>Is that how most vapor glazers do it?
Hi:
I start salting when cone 8 is flat and cone 9 is starting to bend. From
that time until shutdown at 1280 C there's a two hour period of salting and
then regaining temp until the endpoint is reached. There's plenty of time
there for salt to affect the cones in the kiln. I use a Fluke digital pyro
with a shielded thermocouple to record the kilns temp. There's always a
big lag between the cones and the actual temp readout with the
pyrometer. The cones go down at least one cone ahead of where they should
be. There's also residual salt vapor from previous firings that may affect
the cones.
Another way to bypass cones as the actual indicator of what's going on in
the kiln is draw trials. I use these to judge the amount of salt glaze
buildup on the pots. I also have applied slips and glazes to the draw
rings fo see how they are being affected by heat and salt.
regards, Craig Martell Hopewell, Oregon
iandol on fri 9 jan 04
Dear Taylor Hendrix,
You suggest,<the claybody's heat treatment, effect of vapor on the cone pack ain't =
all that. >>
This thought ignores the possibility that there have been numerous =
firings previously and that earlier oversalting will not influence the =
outcome.
It also calls into question the reliability or durability of clay salted =
or soddad(sic) at a lower temperature than that which gives ideal =
vitrification.
Start keeping notes on salt. Copy and paste what I say!!!
Best regards,
Ivor Lewis. Redhill, South Australia
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