Joyce Lee on fri 25 may 01
I just looked into the gas Geil downdraft kiln, now that yesterday's ^10 =
firing has finally cooled .... and was disappointed to see that the =
shino shallow bowl/deep platter's big, floppy rim has fallen. I've fired =
this same form... on the top shelf, as this one is ... to ^12 ... never =
have had the rims fall. =20
Now I'm wondering about the posts some of you have written concerning =
"propping" on edge your platters or plates for firing... thinking maybe =
that would keep this from happening again. If you don't mind =
re-hashing old material, could you please then explain just how does one =
do this? Prop against what? Do you then not glaze the back side of =
such plates? I have a fiber kiln coated with ITC ... would that matter? =
I'm irritated with myself for not asking before when you were posting =
about it. The colors look good.... the shino is mottled black/grey with =
green/black in the bottom middle of the bowl.
Also, this firing went faster than usual ... not quite six hours... =
would that affect the rim?
Thank you for sharing your thinking.
Joyce
In the Mojave
Dannon Rhudy on sat 26 may 01
Joyce said:
.... disappointed to see that....shallow bowl/deep platter's big, floppy
rim has fallen. .... wondering about ....."propping" on edge your platters
or plates for firing... ....
Joyce, my experience is that "big floppy rims" or indeed nearly ANY
rim will fall or warp in two instances: if the foot of the piece is too far
inside the edge, and/or if the "rise" of the rim is too shallow/weak.
It could be in this instance that there was something slightly different
about the way you made it, and therefore the rim sag/warp.
The foot should be placed at or just inside the place where the rim
starts to rise from the base of the piece, and the SLOPE or
angle of rise of the rim must be sufficient to maintain/support
the shape. If the rim is too wide or the rise is too shallow,
it warps.
Firing on edge can only be done in BISQUE firings. For large
pieces, even unglazed, firing on the rim to ^10-12 will cause
some warpage. Further, you wouldn't be able to glaze your
work. In wood firing some plates/platters are fired on edge,
but there is not glaze to worry about, wadding is used as a
support, and if there is some warpage it doesn't ruin the piece.
More often in wood firing a large plate/platter will be fired
on it's rim, supported strategically all round, or with the wadding
supporting the inside, just where the rim starts it's rise. In
these situations the rim hangs upside down in a flare, and
generally stays unwarped.
If I did not make the word-picture clear, email me off-list and I'll
try again and/or scan a drawing.
regards
Dannon Rhudy
Joyce Lee on sat 26 may 01
I've been offered some very sound ... and doable ... suggestions for =
prevention of fallen rims next firing. Was about to give up and return =
to the slightly smaller forms .... but now think I might be able to make =
the bigger ones work. Actually, I'm not sure why I even want to ... =
they're too big for easy storage and too overpowering for many =
coffeetables ... and the rims are too ruffly for wall hanging. But =
somehow I just like the big floppy looking rims that LOOK as if they're =
about to fall... or just missed falling ... no idea why. Maybe find =
appealing the concept of being on the verge of disaster, but always =
being saved... or saving someone or something else... just in the knick =
of time ... missing out on one more loss, at least THIS time...... =
gettin' too psycho for ya? Betcha the mayor is ready to barf....
Sooo... will throw the support part of the rim thicker ... and perhaps =
make the whole platter/shallow bowl thicker, too... avoid right angles =
that hang in the air, smoothing them to make the line more continuous. =
(It's true, I do like those irregular angles, but in this case will =
leave them for the area where the rim flattens out at the edge. How DO =
you people know what I'm doing out here, anyhow?)
Feet will be placed as Dannon suggests, and not made too small. If I =
don't have feet, I'll fire on a bed of silica sand, creating those teeny =
ball bearings to allow rolling around room.
I'll fire slower, especially slowing at the end of the firing. I did not =
know that 300-350 degrees F. an hour could be a good rule of thumb. I =
fire my bisque slowly AFTER candling for several hours, but just =
generally followed the glaze firing guidelines for my kiln, not even =
thinking about how many degrees an hour is a good idea.
I'll be pondering all this (and more) today while still getting the hang =
of the extruder ... no wheel work for a couple of weeks while I try all =
the dies, ideas etc ... and fire my trays which are patiently awaiting =
Sheila's decorative cane trims. Extruded a large, tall (well, of course, =
tall!) square box with lid similar to one in Diana's book ... =
gorgeous!... and two 6" bowl forms ... not so gorgeous... only took me =
half a day ... put that dang clay through about 18 times ... but I think =
I'm gonna OWN that dratted process before it's over... as long as it's =
limited to boxes and 6" bowls.
If even one beautifully attired friend arrives this afternoon, without =
clay attached to odd spots on her person, and with perfectly manicured =
fingernails on the ends of lotioned and perfumed hands, and the fresh =
makeover they're giving out at a local salon .... and says, "it must be =
so soothing to work with clay; you're so lucky to have a hobby that you =
enjoy so much"... I swear, I'll smack her one... for the "soothing" =
part... the "lucky" part is deadon true!=20
Joyce
In the Mojave so tickled to hear that Jonathan in D.C. (Kirkendahl) won =
the grant for Miriam's Kitchen ... feeds the homeless among other noble =
deeds ... first time through, he and his partner WON. Congratulations =
are definitely deserved. Good job, my good bud.
Bob Hanlin on sun 27 may 01
My platters have done that and after breaking them and looking at the cross
sections I found that I had trimmed them too thinly near the foot and the
wieght of the rim section just fell down. I now leave them a bit thicker
and they do fine.
B.
----- Original Message -----
From: "Dannon Rhudy"
To:
Sent: Saturday, May 26, 2001 7:04 AM
Subject: Re: Firing Platters/Shallow Bowls
> Joyce said:
>
> ..... disappointed to see that....shallow bowl/deep platter's big, floppy
> rim has fallen. .... wondering about ....."propping" on edge your platters
> or plates for firing... ....
>
>
> Joyce, my experience is that "big floppy rims" or indeed nearly ANY
> rim will fall or warp in two instances: if the foot of the piece is too
far
> inside the edge, and/or if the "rise" of the rim is too shallow/weak.
> It could be in this instance that there was something slightly different
> about the way you made it, and therefore the rim sag/warp.
>
> The foot should be placed at or just inside the place where the rim
> starts to rise from the base of the piece, and the SLOPE or
> angle of rise of the rim must be sufficient to maintain/support
> the shape. If the rim is too wide or the rise is too shallow,
> it warps.
>
> Firing on edge can only be done in BISQUE firings. For large
> pieces, even unglazed, firing on the rim to ^10-12 will cause
> some warpage. Further, you wouldn't be able to glaze your
> work. In wood firing some plates/platters are fired on edge,
> but there is not glaze to worry about, wadding is used as a
> support, and if there is some warpage it doesn't ruin the piece.
> More often in wood firing a large plate/platter will be fired
> on it's rim, supported strategically all round, or with the wadding
> supporting the inside, just where the rim starts it's rise. In
> these situations the rim hangs upside down in a flare, and
> generally stays unwarped.
>
> If I did not make the word-picture clear, email me off-list and I'll
> try again and/or scan a drawing.
>
> regards
>
> Dannon Rhudy
>
>
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MaryBeth Bishop on mon 28 may 01
I've found that I have better luck with shallow bowls and small feet when I
first throw the walls vertically and then open them at the end. The clay
memory thing seems to work for me. Also, using very little water. Of course
all my bowl warp but that is because I am always a little off center and
really like them a little wavy.
Mary Beth Bishop
in Durham listening to raindrops and birdsongs
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