Steve Mills on sat 8 nov 08
Dear Randy,
I bisque all bowls in stacks with three bits of ceramic fibre between each one, and three under the bottom one. This allows good heat circulation, and stops them being "pinned down" by the weight of those above. I also do this with big Planters.
I haven't lost one yet!
The bits of ceramic fibre (about 2cm square) are constantly re-used, and have been for the last 20 years.
Steve
Bath
UK
--- On Sat, 11/8/08, Randy McCall wrote:
From: Randy McCall
Subject: Bisquing 12inch bowls?
To: CLAYART@LSV.CERAMICS.ORG
Date: Saturday, November 8, 2008, 11:00 AM
Is there any problem with nesting 12 inch bowls when bisquing. I do not
want these bowls to crack as I have a lot to get done.
Randy
Cotton Patch Pottery
members.tripod.com/~McCallJ/index.html
Randy McCall on sat 8 nov 08
Is there any problem with nesting 12 inch bowls when bisquing. I do not
want these bowls to crack as I have a lot to get done.
Randy
Cotton Patch Pottery
members.tripod.com/~McCallJ/index.html
Hank Murrow on sat 8 nov 08
On Nov 8, 2008, at 8:57 AM, Lynn Goodman Porcelain Pottery wrote:
> As long as the bowls can move freely within each other, it should be
> fine. If they catch or are tight you will get cracks when they shrink
> in the bisque.
Good advice from Lynn;
And I might add that sometimes I put a piece of thin kiln shelf or
bisque between bowls to raise them inside each other to create
clearance. i can go eight or ten high with large salad bowls if the
pressure goes down from foot to foot.
I stack all my plates and platters on their edge..... I get twelve
dozen in one bisque.
Cheers, Hank
Lynn Goodman Porcelain Pottery on sat 8 nov 08
As long as the bowls can move freely within each other, it should be
fine. If they catch or are tight you will get cracks when they shrink
in the bisque.
Lynn
On Nov 8, 2008, at 6:00 AM, Randy McCall wrote:
> Is there any problem with nesting 12 inch bowls when bisquing. I
> do not
> want these bowls to crack as I have a lot to get done.
>
> Randy
>
> Cotton Patch Pottery
> members.tripod.com/~McCallJ/index.html
KATHI LESUEUR on sat 8 nov 08
On Nov 8, 2008, at 11:57 AM, Lynn Goodman Porcelain Pottery wrote:
> As long as the bowls can move freely within each other, it should be
> fine. If they catch or are tight you will get cracks when they shrink
> in the bisque.
>
> Lynn
>
>
> On Nov 8, 2008, at 6:00 AM, Randy McCall wrote:
>
>> Is there any problem with nesting 12 inch bowls when bisquing. I
>> do not
>> want these bowls to crack as I have a lot to get done.
>>
>> Randy
>>
>> Cotton Patch Pottery
>> members.tripod.com/~McCallJ/index.html
>
I think it depends on your clay. I wouldn't next a bowl this size.
I'd be worried about cracking from the weigh of one bowl on the
other. My clay is pretty sensitive to this. I do fire bowls in what
I'd call a reverse nest. I usually fire bowls upside down. I'll nest
them so that smaller bowls are inside of larger. The trick is to make
sure none of the bowls are resting on the others.
Kathi
William & Susan Schran User on sat 8 nov 08
On 11/8/08 6:00 AM, "Randy McCall" wrote:
> Is there any problem with nesting 12 inch bowls when bisquing. I do not
> want these bowls to crack as I have a lot to get done.
No problem, as long as the foot of the nesting bowl sits over the foot of
the one holding it. If the nesting one rests on the interior sides of the
one below, that's where you'll have problems.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Larry Kruzan on sat 8 nov 08
Hi Randy,
This might not help you now if you are in a time crunch but here is what I
did.
A couple years ago I extruded a few solid rectangular bars (1/2x1" in
cross-section) which I cut into a bunch 1" pieces. After drying them they
were bisque fired and then high fired (unglazed). Now when I'm stacking
plates or bowls in the kiln for a bisque fire I used these blocks as
separators.
This allows plenty of room for nested items to "flex" and shrink as they
fire without binding against each other.
This is not a new or original idea I have since seen this idea shown in a
couple books and it was used in a commercial factory I once visited.
Best Wishes,
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Randy McCall
Sent: Saturday, November 08, 2008 5:00 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: [CLAYART] Bisquing 12inch bowls?
Is there any problem with nesting 12 inch bowls when bisquing. I do not
want these bowls to crack as I have a lot to get done.
Randy
Cotton Patch Pottery
members.tripod.com/~McCallJ/index.html
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Earl Brunner on sat 8 nov 08
Nesting always depends on where the weight pressure goes. If it is linear downward through the foot rims, then it will probably be OK, it the foots don't align, or the pressure is outward on the sides of any of the bowls then there is a potential problem. It also depends on heating and cooling. Electric firing with the heat radiating in, from the sides and the way electric kilns cool c can have an affect on wider rimmed pieces. In our electrics this is mostly a problem with refires in the glaze firing though.
Earl Brunner
Las Vegas, NV
________________________________
From: KATHI LESUEUR
To: CLAYART@LSV.CERAMICS.ORG
Sent: Saturday, November 8, 2008 9:23:48 AM
Subject: Re: Bisquing 12inch bowls?
>
> On Nov 8, 2008, at 6:00 AM, Randy McCall wrote:
>
>> Is there any problem with nesting 12 inch bowls when bisquing. I
>> do not
>> want these bowls to crack as I have a lot to get done.
>>
>> Randy
>>
>> Cotton Patch Pottery
>> members.tripod.com/~McCallJ/index.html
>
I think it depends on your clay. I wouldn't next a bowl this size.
I'd be worried about cracking from the weigh of one bowl on the
other. My clay is pretty sensitive to this. I do fire bowls in what
I'd call a reverse nest. I usually fire bowls upside down. I'll nest
them so that smaller bowls are inside of larger. The trick is to make
sure none of the bowls are resting on the others.
Kathi
Vince Pitelka on sat 8 nov 08
Randy from Cotton Patch Pottery wrote:
"Is there any problem with nesting 12 inch bowls when bisquing. I do not
want these bowls to crack as I have a lot to get done."
Randy -
Yes, there's a big problem, but it is easily remedied. If you fire them
nestled inside each other with nothing separating them, you will likely lose
some of them. When I was making pots full-time 25 years ago I made a lot of
sets of mixing bowls in two-inch increments from 6 inches to 16 inches. At
first I tried firing them nestled inside each other, and I lost a lot of
them. Either they would crack, or else the bottom of one or more bowls in
the middle of the stack would just shatter into fine shards and powder. The
solution was to separate them with small softbrick shims, which I re-used
again and again. You could also use small wads of 50% scrap slurry (or any
dry clay) and 50% flint. I cut thin slices from a softbrick and broke those
slices up into small pieces. I put the largest bowl on the shelf, put three
shims equally spaced around the bottom, placed another bowl, three more
shims in the same location as the previous ones, another bowl, etc. I would
nestle a full set of mixing bowls that way. I also did (and still do) the
same thing with serving bowls and plates, often firing a stack of the same
size of bowl or plate with shims separating them. I don't think I ever lost
another bowl or plate from cracking or shattering in the bisque-firing
unless there was some other obvious cause.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Ann Brink on sun 9 nov 08
Hello all,
I think the point made by many is that it's a good idea to slightly separate
the bowls one is nesting in the kiln. I can't resist telling you all what I
have been using for this purpose: short lengths of porcelain rod that I
salvaged from some old electric kiln I got at a yard sale. The rods are
about 3/16th inch in diameter and were inside the element coils. Do any
old-timers remember kilns like that? To use them, I place 3 pieces of rod
equidistantly on the bottom inside of a bowl, perpendicular to the edge. If
the inside bowl needs to move, it can roll a little.
...an example of using what is at hand.
Ann Brink in Lompoc CA
(mostly about pottery)
----- Original Message -----
From: "Robert W. Anderson"
To:
Sent: Sunday, November 09, 2008 5:29 PM
Subject: Re: Bisquing 12inch bowls?
> My turn.....Try nesting your platters, bowls; etc
> on broken pieces of bisqueware. Use three...
> under the foot ring...each about the diameter
> of a nickel. The weight of each bowl / platter
> will determine how high you can stack.
>
>
john dellow on sun 9 nov 08
Randy McCall wrote:
> Is there any problem with nesting 12 inch bowls when bisquing. I do no=
t
> want these bowls to crack as I have a lot to get done.
>
> Randy
>
> Cotton Patch Pottery
> members.tripod.com/~McCallJ/index.html
>
>
>
> =20
you could nest in sand. a white washed river sand .
--=20
John Dellow
The potter formelly known as=20
=91The Flower Pot Man=92
www.welcome.to/jkdellow
http://www.flickr.com/photos/sagers/
Snail Scott on sun 9 nov 08
On Nov 8, 2008, at 5:00 AM, Randy McCall wrote:
> Is there any problem with nesting 12 inch bowls when bisquing...
They should be fine as long as they are not tightly
nested, and you fire nice and slow.
The problem with tightly nested bisque is that the
outer bowls heat up first, expanding and allowing the
inner bowls to nestle a little further down inside if the
angles allow for it. Then, they cool quickest, too, and
shrink first, and if there isn't enough room between them
and the (still heat-expanded) inner bowls, they will
crack. Too fast a firing (and especially too fast a cooling)
can exacerbate these problems. Thermal shock isn't
as much an issue as heat expansion and contraction.
If your forms are too tight (as nesting bowls often are),
try using little spacer wads between them. This will also
allow better air circulation for drying during candling. If
they rest on each others' rims (allowing them to drop
down as they fire), you may need bigger spacers, or
put little cups or other small work between them.
-Snail
May Luk on sun 9 nov 08
Dear Hank;
I want to try the edge stacking method.
When stacking plates on their edge, wouldn't some green ware edge be touchi=
ng the side of the kiln where the element is? Will that be okay?
Thanks
May
Brooklyn NY
[...]
>=20
> And I might add that sometimes I put a piece of thin kiln
> shelf or
> bisque between bowls to raise them inside each other to
> create
> clearance. i can go eight or ten high with large salad
> bowls if the
> pressure goes down from foot to foot.
>=20
> I stack all my plates and platters on their edge..... I get
> twelve
> dozen in one bisque.
>=20
> Cheers, Hank=0A=0A=0A
Victoria E. Hamilton on sun 9 nov 08
Randy -
Try a layer of vermiculite between each bowl - works for me.
Vicki Hamilton
Millennia Antica Pottery
Seattle, WA
Robert W. Anderson on sun 9 nov 08
My turn.....Try nesting your platters, bowls; etc
on broken pieces of bisqueware. Use three...
under the foot ring...each about the diameter
of a nickel. The weight of each bowl / platter
will determine how high you can stack.
Robert Anderson
Antigo, Wis.
=================
http://webpages.charter.net/rwapottery/index.html
----- Original Message -----
From: "Victoria E. Hamilton"
To:
Sent: Sunday, November 09, 2008 1:32 PM
Subject: Re: Bisquing 12inch bowls?
> Randy -
>
> Try a layer of vermiculite between each bowl -
works for me.
>
> Vicki Hamilton
> Millennia Antica Pottery
> Seattle, WA
>
>
> --
> No virus found in this incoming message.
> Checked by AVG.
> Version: 7.5.549 / Virus Database:
270.9.0/1776 - Release Date: 11/8/2008 6:49 PM
>
>
Ron Roy on tue 18 nov 08
Hi Randy,
Aside from what others have contributed - some clays have a lot of organics
in them - that has to be burned out during the bisque firing. When you nest
pots or fire them rim to rim you will need to take that factor into
account.
If you make it hard for the oxygen to get to every part of the pot and
there is iron present - you can have over fluxed clay were the iron gets
reduced and becomes a serious flux.
Read Hamer on black coring to understand the process.
If you do nest and are using a clay that needs a clean burn - adjust your
firing cycle and make sure there is plenty of oxygen around to ensure a
clean burn.
RR
>Is there any problem with nesting 12 inch bowls when bisquing. I do not
>want these bowls to crack as I have a lot to get done.
>
>Randy
>
>Cotton Patch Pottery
>members.tripod.com/~McCallJ/index.html
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Randy McCall on tue 18 nov 08
Ron thanks for the comment and others also. The next time I bisque bowls I
am going to try some old elements to separate the bowls and make sure I fire
5 or 6 hours on Med.
Randy
Cotton Patch Pottery
members.tripod.com/~McCallJ/index.html
----- Original Message -----
From: "Ron Roy"
To:
Sent: Tuesday, November 18, 2008 12:57 AM
Subject: Re: Bisquing 12inch bowls?
> Hi Randy,
>
> Aside from what others have contributed - some clays have a lot of
> organics
> in them - that has to be burned out during the bisque firing. When you
> nest
> pots or fire them rim to rim you will need to take that factor into
> account.
>
> If you make it hard for the oxygen to get to every part of the pot and
> there is iron present - you can have over fluxed clay were the iron gets
> reduced and becomes a serious flux.
>
> Read Hamer on black coring to understand the process.
>
> If you do nest and are using a clay that needs a clean burn - adjust your
> firing cycle and make sure there is plenty of oxygen around to ensure a
> clean burn.
>
> RR
>
> >Is there any problem with nesting 12 inch bowls when bisquing. I do not
> >want these bowls to crack as I have a lot to get done.
> >
> >Randy
> >
> >Cotton Patch Pottery
> >members.tripod.com/~McCallJ/index.html
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
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