The Brinks on wed 28 jun 00
Sure, it's done all the time. If it's pretty big or heavy, I'd put a little
frog under the feet, oh, a typo!!!! ...I mean grog of course.
Ann Brink in CA
----- Original Message -----
From: Ortynsky Family
To:
Sent: Wednesday, June 28, 2000 2:55 PM
Subject: firing large platters
I need to fire a large rectangular platter which has 6 knobs for feet in a
cone 6 fire. I have only half shelves that is to say I will have to fire
this dish across two shelves. Is this advisable?
thanks in advance for your help : Catherine Ortynsky: ortynsky@ocol.com
Frozen John Studios
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Ortynsky Family on wed 28 jun 00
I need to fire a large rectangular platter which has 6 knobs for feet in =
a cone 6 fire. I have only half shelves that is to say I will have to =
fire this dish across two shelves. Is this advisable? =
thanks in =
advance for your help : Catherine Ortynsky: ortynsky@ocol.com=20
=
=
Frozen John Studios
Cat Jarosz on thu 29 jun 00
Dear Catherine , I fire platters across shelves all the time ...
never had any trouble untill recently with 10 yr old shelves that have
warped out a bit ... new shelves fixed that right up ... as long as
your shelves are level flat across the split you shouldnt have a problem
... I"ve done some quick fixes using fiber blanket as shims under the
posts holding the shelves to try to level it some to some success ...
but check your platter and if it wobbles on those shelves it will come
out warped to the level of your shelves ... go get new shelves if
you can. Cat
iandol on thu 29 jun 00
Dear Catherine,
I can see no reason, if the shelves are levelled true to an equal =
elevation with a spirit level, why this should not work.
However=85
One of the major problems when firing large platters or other items =
which cover most of the area of your kiln is dunting. It is very =
difficult to maintain a uniform temperature across the area of a kiln as =
it cools. The least slight draft impinging on the pot can cause a =
catastrophe.
I have overcome this problem in the past by making draught excluders, =
shields of flat clay which I make so they stand on their edge, almost =
like a removable saggar. These need to be fairly thick so that they have =
a reasonable heat mass which will delay cooling and help to keep the =
temperature gradient across your pot as even as possible. This idea is =
illustrated in DeBoos, Smith and Harrison, Handbook for Australian =
Potters. Pp 210-1. ISBN 0-454-00448-6
In addition, I would suggest that you clam the fireports and close the =
damper to prevent cold air being sucked into the interior of your kiln.
All the best with this.
Ivor Lewis. Redhill, South Oz
Earl Brunner on thu 29 jun 00
Sorry, I've been busting up every time I think of it all
day. I visualize these little frogs laying on their backs
with the feet of this platter on their stomachs........
The Brinks wrote:
>
> Sure, it's done all the time. If it's pretty big or heavy, I'd put a little
> frog under the feet, oh, a typo!!!! ...I mean grog of course.
>
> Ann Brink in CA
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Cindy Strnad on fri 30 jun 00
Catherine,
You shouldn't have any trouble related to using two shelves, since the
platter is footed. Do be sure the shelves provide as level a surface as
possible.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
earthenv@gwtc.net
Veena Raghavan on fri 30 jun 00
Message text written by Ceramic Arts Discussion List
>Sorry, I've been busting up every time I think of it all
day. I visualize these little frogs laying on their backs
with the feet of this platter on their stomachs........
<
First of all, I want to thank Earl for a great laugh! I am so stressed out
with this move, that it was great to burst into laughter reading his post!
On the subject of firing large platters with feet, as I remember through my
packing fog, the platter had feet, I either read on Clayart or somewhere
else, that it is always good to put any largish item with feet onto a large
clay cookie to fire. I have done this and have put a wash of alumna hydrate
on the feet and the cookie. I do not know if this would be a problem, when
spanning the join between the two shelves, but maybe any shift would be
absorbed by the cookie. Just a suggestion, and maybe the experts could
comment on this.
Veena
Veena Raghavan
75124.2520@compuserve.com
Liz Harris on thu 13 jan 05
Hello all,
I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3 electric kiln;
these are roughly 20 inches in diameter with a 9-inch diameter foot. I have been
told that ware of this size should sit on a single shelf during the glaze firing to reduce
stress on the piece. Problem is, Paragon only supplies half-shelves for my kiln. Is it
truly necessary to do so? If so, can I get around the problem by placing the ware on
a smaller kiln shelf (somewhat larger than the foot) and then putting the smaller shelf
on two half-shelves within the kiln?
Many thanks,
Liz
Earl Brunner on thu 13 jan 05
Yes you can do what you discribe, the idea is to have the whole foot on the same surface.
Liz Harris wrote:Hello all,
I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3 electric kiln;
these are roughly 20 inches in diameter with a 9-inch diameter foot. I have been
told that ware of this size should sit on a single shelf during the glaze firing to reduce
stress on the piece. Problem is, Paragon only supplies half-shelves for my kiln. Is it
truly necessary to do so? If so, can I get around the problem by placing the ware on
a smaller kiln shelf (somewhat larger than the foot) and then putting the smaller shelf
on two half-shelves within the kiln?
Many thanks,
Liz
______________________________________________________________________________
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You may look at the archives for the list or change your subscription
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Earl Brunner
e-mail: brunv53@yahoo.com
Craig Clark on thu 13 jan 05
Liz, I've fired quite a few platters and shallow bowls that are
twenty inch diameter. I placed them on a split shelf. I've never really
had much trouble after I learned how to dry them and fire properly.
Consult the archives for numerous references for keeping the edges of
the pieces from cooling more quickly than the middle which is one of the
more common causes of trouble.
If the diameter of the foot ring isn't too large you can go ahead
and span the split with a smaller shelf that is large enough to
accomodate the foot. Try placing posts/small pots around the perimeter
to help the piece cool more evenly.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
Mike Gordon on thu 13 jan 05
Liz,
Try using 2 half shelves with kiln posts the same size. This should
give you the full shelf support. But you really only need a shelf a
little gigger than the foot, maybe a broken one. Mike Gordon
On Jan 13, 2005, at 7:00 AM, Liz Harris wrote:
> Hello all,
>
> I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3
> electric kiln;
> these are roughly 20 inches in diameter with a 9-inch diameter foot.
> I have been
> told that ware of this size should sit on a single shelf during the
> glaze firing to reduce
> stress on the piece. Problem is, Paragon only supplies half-shelves
> for my kiln. Is it
> truly necessary to do so? If so, can I get around the problem by
> placing the ware on
> a smaller kiln shelf (somewhat larger than the foot) and then putting
> the smaller shelf
> on two half-shelves within the kiln?
>
> Many thanks,
> Liz
>
> _______________________________________________________________________
> _______
> 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.
>
john elder on thu 13 jan 05
liz, what you sugguested works well. I also turn the platter over and wet
the waxed rim with spit, which works better than water and then sprinkle
sand on the bottom. It will only adhere to the rim and that helps with the
expansion during firing.
works for me!
John Elder
>From: Liz Harris
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: firing large platters
>Date: Thu, 13 Jan 2005 10:00:36 -0500
>
>Hello all,
>
>I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3
>electric kiln;
>these are roughly 20 inches in diameter with a 9-inch diameter foot. I
>have been
>told that ware of this size should sit on a single shelf during the glaze
>firing to reduce
>stress on the piece. Problem is, Paragon only supplies half-shelves for my
>kiln. Is it
>truly necessary to do so? If so, can I get around the problem by placing
>the ware on
>a smaller kiln shelf (somewhat larger than the foot) and then putting the
>smaller shelf
>on two half-shelves within the kiln?
>
>Many thanks,
>Liz
>
>______________________________________________________________________________
>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.
Earl Brunner on thu 13 jan 05
ok
--- Earl Brunner wrote:
> Yes you can do what you discribe, the idea is to
> have the whole foot on the same surface.
>
> Liz Harris wrote:Hello all,
>
> I'd like to start firing large pieces to cone 6 in
> my Paragon SnF 28-3 electric kiln;
> these are roughly 20 inches in diameter with a
> 9-inch diameter foot. I have been
> told that ware of this size should sit on a single
> shelf during the glaze firing to reduce
> stress on the piece. Problem is, Paragon only
> supplies half-shelves for my kiln. Is it
> truly necessary to do so? If so, can I get around
> the problem by placing the ware on
> a smaller kiln shelf (somewhat larger than the foot)
> and then putting the smaller shelf
> on two half-shelves within the kiln?
>
> Many thanks,
> Liz
>
>
______________________________________________________________________________
> 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.
>
>
>
> Earl Brunner
> e-mail: brunv53@yahoo.com
>
>
______________________________________________________________________________
> 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.
>
=====
Earl Brunner
e-mail: brunv53@yahoo.com
Vince Pitelka on thu 13 jan 05
> I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3
> electric kiln;
> these are roughly 20 inches in diameter with a 9-inch diameter foot. I
> have been
> told that ware of this size should sit on a single shelf during the glaze
> firing to reduce
> stress on the piece. Problem is, Paragon only supplies half-shelves for
> my kiln. Is it
> truly necessary to do so? If so, can I get around the problem by placing
> the ware on
> a smaller kiln shelf (somewhat larger than the foot) and then putting the
> smaller shelf
> on two half-shelves within the kiln?
Liz -
Ideally, it would be better to fire such platters on a single shelf, but it
is not necessary. Just make sure that your posts are firmly seated, and the
shelves are firmly seated on the stilts, and then fire the platter on
wadding, in both the bisque and glaze firings. Just mix up a wadding of
50-50 silica and kaolin, or 50-50 silica and any scrap claybody. Roll that
into 1/2"-diameter coils, and lay a starburst pattern of a dozen or so short
coils in a such a way that the foot ring will sit on those coils. Set the
plate very gently onto the damp coils, so that it just nestles down onto
them without squashing them. Then, your platter will be perfectly evenly
supported, and heat and atmosphere will be able to circulate beneath the
platter, decreasing the liklihood of cracking during heating or cooling. Be
sure to preheat the bisque-firing slowly in order to dry out the coils.
You can use the same system in the glaze firing, but again, preheat slowly
to dry out the coils. Otherwise you can glaze-fire at normal speed. The
50% silica in the wadding mixture means that it can be fired fast.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Cindy on thu 13 jan 05
Hi, Liz.
If your shelves are not warped, you can actually span the two half-shelves,
leaving a crack between to allow more air to get to the piece. This also
facilitates movement of the piece. If they are warped, doing this may or may
not cause trouble, depending on your design, the thickness of your piece,
and your clay.
Your idea sounds like a good one. But I would place the additional shelf on
its own short posts. I would also place a post under the long, flat edge of
each of the shelves your extra shelf sits on. Another solution would be to
use a plate stacker.
Whenever you're firing a heavy piece with a large, flat base, it's good to
give it the opportunity to move on the shelf. You can sprinkle some silica
sand or grog on the shelf. If you're using a ventilation system, though, or
even keeping the upper and lower peepholes open for too long, the sand could
end up in your glaze. You can also use little fired clay rollers to do the
same job.
Good luck,
Cindy in SD
Earl Brunner on thu 13 jan 05
Several people have stated that you can fire across two shelves. This is true, however it is REALLY critical that the two shelves be FLAT and LEVEL. That is why is is easier if you can place the foot rim on ONE shelf. Sometimes it can be really difficult to get two shelves flat and level, this generally becomes harder the higher up you go in the stack.
> I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3
> electric kiln;
> these are roughly 20 inches in diameter with a 9-inch diameter foot. I
> have been
> told that ware of this size should sit on a single shelf during the glaze
> firing to reduce
> stress on the piece. Problem is, Paragon only supplies half-shelves for
> my kiln. Is it
> truly necessary to do so? If so, can I get around the problem by placing
> the ware on
> a smaller kiln shelf (somewhat larger than the foot) and then putting the
> smaller shelf
> on two half-shelves within the kiln?
Earl Brunner
e-mail: brunv53@yahoo.com
Terri Kennedy on tue 18 jan 05
Hi, I get around this problem by putting my big platters on a smaller whole
shelf...just big enough for the bottom of the piece and sit that shelf on
top of my half shelves. Hope this helps.
----- Original Message -----
From: "Liz Harris"
To:
Sent: Thursday, January 13, 2005 9:00 AM
Subject: firing large platters
> Hello all,
>
> I'd like to start firing large pieces to cone 6 in my Paragon SnF 28-3
electric kiln;
> these are roughly 20 inches in diameter with a 9-inch diameter foot. I
have been
> told that ware of this size should sit on a single shelf during the glaze
firing to reduce
> stress on the piece. Problem is, Paragon only supplies half-shelves for
my kiln. Is it
> truly necessary to do so? If so, can I get around the problem by placing
the ware on
> a smaller kiln shelf (somewhat larger than the foot) and then putting the
smaller shelf
> on two half-shelves within the kiln?
>
> Many thanks,
> Liz
>
>
____________________________________________________________________________
__
> 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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