Ann Brink on wed 24 oct 07
Randy, every time I fire a platter that size, also in a manual Skutt, I do
several things:
Have a sprinkling of grog under it (be careful not to get it near the
join of the two shelves during the glaze firing)
Arrange the height of the shelf so the edge of the platter doesn't
directly line up with the coils
Have it in the top half of the kiln: I think the heat rise is more
gradual there, because of propping the lid.
I would go gradually with the medium as well.
I actually turn all 3 elements on low at once, with the lid propped, until
the pyrometer is at about 750, then do the mediums gradually until about 950
F, then close the lid and let everything equalize for at least an hour
before turning them all to High.
Take your time cooling as well.
Good luck
Ann Brink in Lompoc Ca
(mostly about pottery)
----- Original Message -----
From: "Randy McCall"
To:
Sent: Wednesday, October 24, 2007 3:11 PM
Subject: Large Platter,,,firing question???????
>I am going to bisque fire a large platter, that barely fits inside my
> electric kiln. Two edges are around 3/4 to 1/2 inch from the perimeter of
> the kiln close to the brick.
>
> Do you think I can successful fire this piece. I have a manual skutt and
> was planning on putting the bottom on low for an hour, bottom and middle
> on
> low for another hour and all three on low for an hour before going to
> medium
> controls. I am wondering if I need to do the same for the medium
> controls???????
>
> It is probably about 1/4 inch thick or at least not much more than that.
>
>
> Any help would be appreciated to keep this piece from
> blowing...............
>
>
Randy McCall on wed 24 oct 07
I am going to bisque fire a large platter, that barely fits inside my
electric kiln. Two edges are around 3/4 to 1/2 inch from the perimeter of
the kiln close to the brick.
Do you think I can successful fire this piece. I have a manual skutt and
was planning on putting the bottom on low for an hour, bottom and middle on
low for another hour and all three on low for an hour before going to medium
controls. I am wondering if I need to do the same for the medium
controls???????
It is probably about 1/4 inch thick or at least not much more than that.
Any help would be appreciated to keep this piece from blowing...............
Randy
South Carolina
Pottery Web site
http://members.tripod.com/~McCallJ/index.html
Patty Kaliher on wed 24 oct 07
Not sure if you will want to try this, a ceramic artist from Belgium always
bisque fires plates and platters on their rim. She leans them against the
side of the kiln placing a piece of kiln furniture between the top rim of
the plate and the side of the kiln. She sets the plates up three deep and
has never had a problem with cracking.
Furthermore when she glaze fires she puts a very thick coat of klin wash on
the self and then cuts grooves in the kiln wash so air flows under the
plate, it heats and cools evenly and again no cracks.
Your schedule sounds good to me. I would then put all the knobs on medium
for 2 hours before putting them all on high.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Randy McCall
Sent: Wednesday, October 24, 2007 6:11 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Large Platter,,,firing question???????
I am going to bisque fire a large platter, that barely fits inside my
electric kiln. Two edges are around 3/4 to 1/2 inch from the perimeter of
the kiln close to the brick.
Do you think I can successful fire this piece. I have a manual skutt and
was planning on putting the bottom on low for an hour, bottom and middle on
low for another hour and all three on low for an hour before going to medium
controls. I am wondering if I need to do the same for the medium
controls???????
It is probably about 1/4 inch thick or at least not much more than that.
Any help would be appreciated to keep this piece from blowing...............
Randy
South Carolina
Pottery Web site
http://members.tripod.com/~McCallJ/index.html
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__
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John Rodgers on thu 25 oct 07
I too fire big platters that barely fit the kiln.
I first trim the bottom so there is ever so slightly an arc in the
bottom from the edge of the platter bottom to the center so the contact
surface is only at the perimeter of the bottom. I fire the platter on a
full diameter flat shelf with the platter sitting flat. I don't fir on
the rim. The shelf is set 6 inches below the rim of the kiln. The reason
for that is that due to the tight fit of the platter, I cannot get my
hands down in the kiln any further when placing the platter on the
shelf. I fire to cone 6, and coat the shelf with a layer of Alumina
Hydrate powder first, then place the platter on it. This allows the
platter to move freely when firing so as to reduce stresses thereby
reducing the chances o cracking. I fire slowly to 204F and hold for 3
hours to drive out any entrained moisture. Then I fire up slowly. Once
at bisque temp, I allow natural cooling, and absolutely do not open the
kiln until it is at room temperature. One of the things that kills big
platters - or even small ones or plates - is uneven cooling. If the kiln
is opened even a little bit before the kiln is cool to room temp, the
platter will experience uneven cooling from rim to the center and it is
guaranteed to crack - maybe even completely in half. I know from first
hand experience. I was really pushing a load one time, and cooled the
kiln to rapidly - and straight down through the kiln - top to bottom -
I cracked 12 large plates right in half. Hard lesson learned. So slow
fire up - slow cool, do not open the kiln until it is at room
temperature.I now fire really ornate platters - 24 inch - with a lot of
leaf and vine on the rim. I follow exactly the procedure I have
described, and I very rarely get cracking any more. It works.
Good luck.
Regards,
John Rodgers
Randy McCall wrote:
> I am going to bisque fire a large platter, that barely fits inside my
> electric kiln. Two edges are around 3/4 to 1/2 inch from the perimeter of
> the kiln close to the brick.
>
> Do you think I can successful fire this piece. I have a manual skutt and
> was planning on putting the bottom on low for an hour, bottom and middle on
> low for another hour and all three on low for an hour before going to medium
> controls. I am wondering if I need to do the same for the medium
> controls???????
>
> It is probably about 1/4 inch thick or at least not much more than that.
>
>
> Any help would be appreciated to keep this piece from blowing...............
>
>
> Randy
> South Carolina
> Pottery Web site
>
> http://members.tripod.com/~McCallJ/index.html
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
Eleanora Eden on sat 3 nov 07
I had given up trying to fire such platters, cracking was just about guaranteed.
Then RR mentioned making sure to fire such items in the top half of the kiln.
Since then I have not had any problems.
The other thing I do that I think nobody else mentioned is I put a moat of tiles or
kiln posts around the flat item so that the heat isn't going directly onto the rim and
creating that difference in heating. With that platter that fits so tightly I put tiles
around the edge of the shelf so that the elements are heating those tiles directly,
not the platter rim. I do this with all big flat stuff. It has worked great.
I glaze fire with stilts so the piece is never touching the shelf during the glaze fire.
My highest fire is a bisc that is higher than the glaze and on that firing the piece is
directly on the shelf. Haven't had problems. During the first bisc fire I put little
spacer tiles around under the foot so the platter isn't on the shelf.
Eleanora
>I am going to bisque fire a large platter, that barely fits inside my
>electric kiln. Two edges are around 3/4 to 1/2 inch from the perimeter of
>the kiln close to the brick.
>
>Do you think I can successful fire this piece. I have a manual skutt and
>was planning on putting the bottom on low for an hour, bottom and middle on
>low for another hour and all three on low for an hour before going to medium
>controls. I am wondering if I need to do the same for the medium
>controls???????
>
>It is probably about 1/4 inch thick or at least not much more than that.
>
>
>Any help would be appreciated to keep this piece from blowing...............
>
>
>Randy
>South Carolina
>Pottery Web site
>
>http://members.tripod.com/~McCallJ/index.html
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, or change your
>subscription settings here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
--
Bellows Falls Vermont
www.eleanoraeden.com
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