Jeff Brown on tue 1 feb 11
Hey Paul,
I have stacked plates rim to rim, foot to foot with no spacers(but I migh=
=3D
t try=3D20
greenware spacers?) If the rims are thick enough
I have also stacked plates right side up inside each other depending on t=
=3D
he=3D20
shape of the plate...=3D20
epk, or grog on the shelf under the first plate as "ball bearings" sounds=
=3D
good if=3D20
you stack them 6 high
If you do wade them..., don't waste alumina on the wadding.... silica, an=
=3D
d epk=3D20
50/50 is good enough...but aren't you tired of wading all of your pots?
Keep the fire burning...
Jeff Brown
1423 Pottery Highway 705
Seagrove, NC 27341
http://www.jeffbrownpottery.com
On Tue, 1 Feb 2011 19:32:54 +0000, Paul Haigh =3D20
wrote:
> Reading in the archives about people bisque firing plates leaning on th=
=3D
eir=3D20
>rims. I'm worried about warpage.
>
>My other option is to stack them up with small kaowool or wadding suppor=
=3D
ts=3D20
one over the other to create some air space.
>
>What is the current thinking?
>
>Thanks,
>-pH
Paul Haigh on tue 1 feb 11
I never used an electric kiln in my life and am getting ready to do a bisqu=
e fire, including about 50 plates. Reading in the archives about people bis=
que firing plates leaning on their rims. I'm worried about warpage.
My other option is to stack them up with small kaowool or wadding supports =
one over the other to create some air space.
What is the current thinking?
Thanks,
-pH
Paul Haigh
Wiley Hill Mudworks
Web: http://wileyhill.com
Facebook: http://tinyurl.com/28ggv3w
etsy: http://www.etsy.com/shop/WileyHillMudworks
Paul Herman on tue 1 feb 11
Paul,
I stack the plates about five or six high, and between each of the
plates I put three small shards of broken bisque. The shards are about
1/4 inch thick. This allows gasses and heat to get between the plates,
and they bisque fire ok.
best wishes,
Paul Herman
Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/
On Feb 1, 2011, at 11:32 AM, Paul Haigh wrote:
> I never used an electric kiln in my life and am getting ready to do
> a bisque fire, including about 50 plates. Reading in the archives
> about people bisque firing plates leaning on their rims. I'm worried
> about warpage.
>
> My other option is to stack them up with small kaowool or wadding
> supports one over the other to create some air space.
>
> What is the current thinking?
>
> Thanks,
> -pH
John Rodgers on tue 1 feb 11
You might, but are not likely, to get warpage during a bisque fire,
but probably not. Stacking them up to 6 deep, with 1/4 inch greenware
slab cuts between works as uniform spacers to help alleviate the
possibility of warp-age. For the bottom most plate in the stack, spread
some alumina hydrate out over the shelf, and use one of those little
corregated or toothed stainless combs to spread it to the same level
throughout. It will look like a field full of furrows when you have it
right. Place your first plate down on that, and the alumina hydrate will
act almost like roller bearings as the plate shrinks during firing. The
plate will slide nicely and no part will hang on the surface of the
shelf, causing a crack or distortion to form. Of course the plates
stacked on top, will all be shrinking the same rate, so there should be
no problem. One thing, I suggest that your flat clay spacers be
greenware also, so that all parts of the stack shrink at the same rate.
Once glazed, I do a glaze fire using large full round shelves. I prep
the surface of the shelf the same as described above. I have some large
chargers I make, and it takes one shelf for each. I space the shelves
1-1/2 to two inches apart, and because there is so much mass, with both
one shelf per plate, and the plates and the posts, I do the firing very
slowly. You do not want that mass heating up unevenly. You will get
warped rims for sure. When the firing is complete, I allow the kiln to
cool naturally, and I do not remove a peephole plug or crack the lid
until that kiln has been at room temperature for several hours. I was
pushing one time, trying to get a load through, and managed to crack in
half every plate in the kiln, top to bottom. Fortunately I didn't crack
all my round kiln shelves - not even one. But hard lesson learned. I've
never made that mistake again.
While on the subject of round flat things like plates and round kiln
shelves...........!
When drying plates and round, flat objects, the edges tend to dry before
the middle. Therefore it is imperative that such objects be covered so
that the moisture content is pretty constant from the center to the
edge. I place my plates, etc in a plastic bag or under a plastic bag and
allow to dry very slowly. I make 24 in. diameter platters, and the same
procedure is required. When firing, you must follow the same procedure.
If you heat to fast, the rims and the center will expand at different
rates, and cracks or warps may occur. When cooling down, the edge of the
plate will cool faster than the center, and the resulting uneven
distribution of heat causes differing expansion/shrinkage rates, and you
will get a broken plate in the kiln every time. So always keep that heat
differential in mind. Slow cool down to room temp.
Finally, there is one exception to drying of plates and other flat ware
under plastic or cover. If you have a heated space - one that you can
get the temp to 90-100 and hold it - and you have a stout dehumidifier -
you can dry wet green clay to bone dry in about three hours without
cracking. It takes a little playing to get it set up right, but I have
done this. I rented one of those steel shipping containers, parked it
out in the boiling hot summer sun down here in the Deep South, placed
three fans and a dehumidifier inside, and let her rip!. I pumped out
about 50 plates per day, from just formed in soft wet clay, to bone dry
in a few hours. I had a huge production to get out, and that did the
trick. I was drying chalices at the same time in the same space. Worked
great. There was so much water coming from the dehumidifier that I had
to hook a water hose to it to manage the water output. The water from
the dehumidifier is essentially distilled water(no filters so has dust,
etc from the air - so wouldn't consider it potable at all) and it worked
terrifically well for making glazes. Nice to use de-mineralized water in
glazes. Gives better control than tap water.
Well, my $0.02 for the day.
Good luck.
John
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
On 2/1/2011 1:32 PM, Paul Haigh wrote:
> I never used an electric kiln in my life and am getting ready to do a bis=
que fire, including about 50 plates. Reading in the archives about people b=
isque firing plates leaning on their rims. I'm worried about warpage.
>
> My other option is to stack them up with small kaowool or wadding support=
s one over the other to create some air space.
>
> What is the current thinking?
>
> Thanks,
> -pH
>
> Paul Haigh
> Wiley Hill Mudworks
> Web: http://wileyhill.com
> Facebook: http://tinyurl.com/28ggv3w
> etsy: http://www.etsy.com/shop/WileyHillMudworks
>
>
Steve Mills on tue 1 feb 11
I usually rim stack across the kiln.=3D20
I start with a piece of IFB against the kiln wall (it doesn't hurt the elem=
e=3D
nts), and every 4th plate I put in a spacer to promote even heating.=3D20
If for any reason I have to stack vertically, I start with 3 bits of Cerami=
c=3D
fibre on the shelf, and then do the same between each plate. This is becau=
s=3D
e if I don't, I loose a lot of plates due in part to uneven shrinkage (rim =
s=3D
hrinks more than the centre), and in part to the stack "pinning" to the she=
l=3D
f.=3D20
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my Ipod touch=3D
James Freeman on wed 2 feb 11
On Tue, Feb 1, 2011 at 2:32 PM, Paul Haigh wrote:
I never used an electric kiln in my life and am getting ready to do a bisqu=
e
fire, including about 50 plates. Reading in the archives about people bisqu=
e
firing plates leaning on their rims. I'm worried about warpage.
My other option is to stack them up with small kaowool or wadding supports
one over the other to create some air space.
What is the current thinking?
Paul...
Being pretty much self-taught, I just stack my plates directly, nested, and
place them directly on the kiln shelf. Nothing between the plates, and
nothing underneath. Never lost one, though perhaps I am just lucky. This
set (http://www.flickr.com/photos/jamesfreemanstudio/5203367182/) was
bisqued in two stacks of five plates each (I made extras). The 24" platter
(more of a coupe plate than a platter, actually) in this picture (
http://www.flickr.com/photos/jamesfreemanstudio/3698635461/) is one of a se=
t
of three, and I bisqued two in a stack.
I am not necessarily recommending this very direct method, as I seem to be
the only one who fires that way. I started doing it that way because I had
no one to tell me any differently, but it seems to work, and is certainly
less of a chore.
For whatever it may be worth.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Fred Parker on wed 2 feb 11
I stack unglazed greenware plates to no more than four high with nothing
between them and generally bisque to ^04 or ^06 and have not had a proble=
=3D
m.
Fred Parker
Michael Wendt on wed 2 feb 11
I found plates and especially platters can be fired flat if
they are fired
with a good saggar surrounding them. The saggar can be
bricks, kiln posts,
kaowool strips or even clay segments made specifically for
this purpose.
I get best results when the plate layer is bounded above and
below by
taller, more loosely stacked layers to permit the plate
stacks to be
heated more from the top and bottom through the shelf rather
than
from the edge.
Warping during edge on bisque firing disappears during the
glaze firing
at least with my cone 10 clay body.
Regards,
Michael Wendt
On Tue, Feb 1, 2011 at 2:32 PM, Paul Haigh
wrote:
I never used an electric kiln in my life and am getting
ready to do a bisque
fire, including about 50 plates. Reading in the archives
about people bisque
firing plates leaning on their rims. I'm worried about
warpage.
My other option is to stack them up with small kaowool or
wadding supports
one over the other to create some air space.
What is the current thinking?
Paul Haigh on thu 3 feb 11
I got a lot of response on my question. Thanks so much! It looks like the c=
onsensus is that bisque on edge for dry plates works great.
By the way, I asked questions about steamers for woodstoves recently. I mix=
ed 10% kyanite 48 mesh into a clay body (the people at kyanite mining were =
excellent) and made some up. A friend with a beast of a woodstove in his sh=
op will do some torture testing for me (run dry, high heat, etc) before I s=
end them out into the world.
pics: http://tinyurl.com/6d8wnca
http://tinyurl.com/6xgfxfk
Paul Haigh
Wiley Hill Mudworks
Web: http://whmudworks.com
Facebook: http://tinyurl.com/28ggv3w
etsy: http://www.etsy.com/shop/WileyHillMudworks
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