Celia Littlecreek on mon 21 may 01
I checked the archives, couldn't find out anything about my problem.=20
I have started making large, flat Raku pieces for wall decoration. I =
learned a very long time ago, that you never lay them directly on the =
kiln shelf, but on one of the edges. I have had quite a bit of =
breakage, that I have seldom had before. I am also using a different =
clay body and even some of my non-flat pieces are cracking in the kiln =
also. I am fairly sure it is an inferior body. Are there any =
suggestions as to what I might do, or firing directions that will keep =
the flat pieces from cracking? It is too late to go back to my good =
clay body, everything is bisqued and I am trying to be ready for a show =
on June 1. I still have time to fire some pieces by then, and would =
appreciate any help you can give.
I don't want to send another email so I offer this suggestion about =
email and archives. Since joining the list there are quite a few emails =
worth saving. I have a hard time finding what I am looking for in the =
archives, so I have sort of started my own. I created a folder in my =
email called "saved mail". Everything in it is something I think I =
will sometime have a need for, that came from the clayart list. I check =
there first, then the archives. I hope someone hasn't offered this =
suggestion before. (this, I didn't check the archives for) Maybe it is =
so simple that everyone thought there was no need to mention it. I am =
still (semi) computer illiterate, and I was proud of myself for thinking =
of it!
from Rakuer on the Rez, where there is a plague of army worms that have =
eaten all the green on the Popples. Maybe the 35 degree temperature =
will kill them before they devour all the Oaks too. So far, my Lilacs =
are safe.
william schran on tue 22 may 01
Since you've already bisqued to clay I'd recommend standing on small
pieces of IFB and slowing down your raku firing.
Bill
Anne Hunt on tue 22 may 01
Hi, Celia --
You didn't say what your firing schedule is, or about how large is "large"
Without knowing any of that, I'd say slow down your firing, and take the
temp up in smaller increments. Among others, I do 20" - 24" platters and
mirror frames. They always cracked at my usual schedule (@10" at 1 psi,
then up to 3psi until @ 900F, then cover the hole on top except for a slit
and bump it up to 4 1/2 - 5psi for the duration -- total about 45". I
almost double the time now, and rarely have a problem.
That's without pre-warming: large pieces got uneven warming when I put
them on the side of the kiln.
Good firing!
anne & the cats, in sequim, wa
Michael C Hill on tue 22 may 01
----- Original Message -----
From: Celia Littlecreek
Date: Monday, May 21, 2001 9:18 pm
Subject: Flat Raku E-mail Archives
I don't know how your kiln is set up but you might try setting soft
bricks on the shelf and fireing the peices flat. This works for me.
To get around a bad clay body is harder, but preheat them to about 400
first, and once they go into the raku enviorment try to not let the tem
cool down(in the kiln), keep the kiln always going up. Again works for
me.
Richard Jeffery on tue 22 may 01
try firing them flat on a thin layer of sand so that they can move a bit on
the shelf.
Make sure the flame isn't playing directly on the bottom of the shelf so it
heats up hotter/faster than the ware.
Yes, it's probably the clay (technique the same?), but this might help. Try
a spare first!
I take it they are cracking pre-reduction phase? I make flat clock faces -
this saved some 12" x 10" ones that otherwise were all being lost.
Richard
Bournemouth UK
www.TheEleventhHour.co.uk
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Celia Littlecreek
Sent: 22 May 2001 03:19
To: CLAYART@LSV.CERAMICS.ORG
Subject: Flat Raku E-mail Archives
I checked the archives, couldn't find out anything about my problem.
I have started making large, flat Raku pieces for wall decoration. I
learned a very long time ago, that you never lay them directly on the kiln
shelf, but on one of the edges. I have had quite a bit of breakage, that I
have seldom had before. I am also using a different clay body and even some
of my non-flat pieces are cracking in the kiln also. I am fairly sure it
is an inferior body. Are there any suggestions as to what I might do, or
firing directions that will keep the flat pieces from cracking? It is too
late to go back to my good clay body, everything is bisqued and I am trying
to be ready for a show on June 1. I still have time to fire some pieces by
then, and would appreciate any help you can give.
I don't want to send another email so I offer this suggestion about email
and archives. Since joining the list there are quite a few emails worth
saving. I have a hard time finding what I am looking for in the archives,
so I have sort of started my own. I created a folder in my email called
"saved mail". Everything in it is something I think I will sometime have a
need for, that came from the clayart list. I check there first, then the
archives. I hope someone hasn't offered this suggestion before. (this, I
didn't check the archives for) Maybe it is so simple that everyone thought
there was no need to mention it. I am still (semi) computer illiterate, and
I was proud of myself for thinking of it!
from Rakuer on the Rez, where there is a plague of army worms that have
eaten all the green on the Popples. Maybe the 35 degree temperature will
kill them before they devour all the Oaks too. So far, my Lilacs are safe.
____________________________________________________________________________
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You may look at the archives for the list or change your subscription
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Celia Littlecreek on tue 22 may 01
Thanks for the help, I am willing to try anything. Nothing to lose since
everything is bisqued already. Will never use this clay body again. It was
a fluke that it was used in the first place.
----- Original Message -----
From: "Michael C Hill"
To:
Sent: Tuesday, May 22, 2001 1:19 PM
Subject: Re: Flat Raku E-mail Archives
> ----- Original Message -----
> From: Celia Littlecreek
> Date: Monday, May 21, 2001 9:18 pm
> Subject: Flat Raku E-mail Archives
>
> I don't know how your kiln is set up but you might try setting soft
> bricks on the shelf and fireing the peices flat. This works for me.
> To get around a bad clay body is harder, but preheat them to about 400
> first, and once they go into the raku enviorment try to not let the tem
> cool down(in the kiln), keep the kiln always going up. Again works for
> me.
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
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