vince pitelka on tue 14 may 02
> i've been throwing platters as big as i can fit in the kiln (21" wet).
> after a trim i attach a coil (the imperfect, extruded kind) with 'magic
> water' and throw the foot. the platter is dry enough that it doesn't
> collapse when i trim it. i score both surfaces. anyway, the foot sometimes
> pops off in firing. how can i prevent this? put something under the
platter
> so i can trim it wetter? or are there tricks in attaching the coil a
certain
> way?
Brian -
If you are trimming the platter, than why not just trim a foot on the
bottom? I do not understand why you are trying to add a coil foot. But
there could be several problems. I am assuming that you throw these on
large bats. If you don't you should. Then, as soon as the clay is barely
stiff enough, you can place a very large bat over the rim, pick up the
platter with one hand under the lower bat and one hand on top of the upper
bat, and flip the whole thing over. Place the upper bat on the wheel and
center it on a clay cookie or on some lumps of clay on the wheelhead -
anything to keep it from slipping around.
Score the circle THOROUGHLY where you want to put the coil. Add PLENTY of
thick slurry of the same claybody to the scored slurry, but do not score the
freshly rolled or extruded coil. Work your fresh coil into place
thoroughly, so that it displaces all excess slurry. Remove excess slurry,
throw the coil, trim off excess. Cover the platter overnight to allow the
moisture content to equalize.
The feet are probably popping off your platters because you are trapping a
plane of air bubbles in the score marks between the platter and the foot.
That is a very common problem when no slurry or insufficient slurry is used.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Brian Molanphy on tue 14 may 02
jeff and vince wrote:
'> I'm working on some slab plates these days and having to throw feet from
> coils and I was reminded how much easier it is to throw a foot from a
fairly
> UNIFORM coil rather than a lumpy UNEVEN coil.
Jeff -
I used to do a lot of colored clay platters which were slumped face-down on
a big domed plaster bat. I put the bat on the wheel, added a coil and threw
the foot. I did not worry about getting the coil particularly even. I just
used a fairly thick coil, with the contact surface on the back of the
platter very well scored and slurried, apply the coil and smush (technical
terminology) into place, paddle lightly to make sure it is very well
attached, and then moisten with slurry and throw the coil to raise it into a
vertical ridge. With a coil that is thicker than necessary, you end up with
a foot which is uneven in height, but taller than you need, so it is a very
simple matter to cut off the excess with a needle tool, producing a
perfectly level foot. Then it doesn't matter at all if the coil is
initially a bit uneven in thickness.
Best wishes -
- Vince'
how conveniently this thread weaves its way to a question i was ready to
pose. i've been throwing platters as big as i can fit in the kiln (21" wet).
after a trim i attach a coil (the imperfect, extruded kind) with 'magic
water' and throw the foot. the platter is dry enough that it doesn't
collapse when i trim it. i score both surfaces. anyway, the foot sometimes
pops off in firing. how can i prevent this? put something under the platter
so i can trim it wetter? or are there tricks in attaching the coil a certain
way?
thanks for your suggestions,
brian
Snail Scott on thu 16 may 02
At 05:49 PM 5/16/02 -0600, you wrote:
>...if i attach a foot as soon as
>a platter is stiff enough to flip onto its rim, the center of the platter
>collapses while i am throwing the foot.
If you make the same form often, why not make
a wide chuck to support it while you attach
the foot? No need to have it rest on its rim.
-Snail
Brian Molanphy on thu 16 may 02
vince,
i like big feet on these platters, and i would have to trim off loads in
order to turn feet rather than attaching coils. without facility to recycle
clay properly, this would be a waste of clay. if i attach a foot as soon as
a platter is stiff enough to flip onto its rim, the center of the platter
collapses while i am throwing the foot. maybe i need to put something -
socks filled with rice was suggested - underneath the platter to support it
during turning and foot-throwing.
i have always scored both surfaces: now i'll just score the drier surface as
you suggest.
i wonder if coilbuilding principles apply here. instead of placing the whole
coil on the platter and then attaching it, would you recommend attaching the
coil as i put it in place on the platter? say, with the coil held in the
air, i attach it inch by inch til one end meets the other on the platter?
this what i understand to be the crack-free coilbuilding method. but i guess
getting the coil centered would be more difficult.
thnaks, brian
original message:
Brian -
If you are trimming the platter, than why not just trim a foot on the
bottom? I do not understand why you are trying to add a coil foot. But
there could be several problems. I am assuming that you throw these on
large bats. If you don't you should. Then, as soon as the clay is barely
stiff enough, you can place a very large bat over the rim, pick up the
platter with one hand under the lower bat and one hand on top of the upper
bat, and flip the whole thing over. Place the upper bat on the wheel and
center it on a clay cookie or on some lumps of clay on the wheelhead -
anything to keep it from slipping around.
Score the circle THOROUGHLY where you want to put the coil. Add PLENTY of
thick slurry of the same claybody to the scored slurry, but do not score the
freshly rolled or extruded coil. Work your fresh coil into place
thoroughly, so that it displaces all excess slurry. Remove excess slurry,
throw the coil, trim off excess. Cover the platter overnight to allow the
moisture content to equalize.
The feet are probably popping off your platters because you are trapping a
plane of air bubbles in the score marks between the platter and the foot.
That is a very common problem when no slurry or insufficient slurry is used.
Good luck -
- Vince
Dannon Rhudy on fri 17 may 02
A
......the center of the platter
>collapses while i am throwing the foot. maybe i need to put something -
>socks filled with rice was suggested - underneath the platter to support it
>during turning and foot-throwing.....
>
Nils Lou uses a sponge beneath the center of large pieces/platters
etc while trimming a foot. Should work just as well when throwing
a foot. Throw the foot as dry as you possibly can, to prevent
much water soaking into the base while your throwing.
regards
Dannon Rhudy
Donald Goldsobel on fri 17 may 02
The best thing to support the platter while it is trimmed is upholstery foam
rubber. I have several circles in various deiameters and thickness. I use a
bulls-eye level to make sure the platter is level. To keep the foam in one
place, I use a rubber coated bat.(The mesh used to line shelves and put
under things to keep them from slipping)
Much easier than bean bags.
Donald
----- Original Message -----
From: "Brian Molanphy"
To:
Sent: Thursday, May 16, 2002 4:49 PM
Subject: Re: thrown feet on platters- was perfect coil
> vince,
>
> i like big feet on these platters, and i would have to trim off loads in
> order to turn feet rather than attaching coils. without facility to
recycle
> clay properly, this would be a waste of clay. if i attach a foot as soon
as
> a platter is stiff enough to flip onto its rim, the center of the platter
> collapses while i am throwing the foot. maybe i need to put something -
> socks filled with rice was suggested - underneath the platter to support
it
> during turning and foot-throwing.
>
> i have always scored both surfaces: now i'll just score the drier surface
as
> you suggest.
>
> i wonder if coilbuilding principles apply here. instead of placing the
whole
> coil on the platter and then attaching it, would you recommend attaching
the
> coil as i put it in place on the platter? say, with the coil held in the
> air, i attach it inch by inch til one end meets the other on the platter?
> this what i understand to be the crack-free coilbuilding method. but i
guess
> getting the coil centered would be more difficult.
>
> thnaks, brian
>
> original message:
>
> Brian -
> If you are trimming the platter, than why not just trim a foot on the
> bottom? I do not understand why you are trying to add a coil foot. But
> there could be several problems. I am assuming that you throw these on
> large bats. If you don't you should. Then, as soon as the clay is barely
> stiff enough, you can place a very large bat over the rim, pick up the
> platter with one hand under the lower bat and one hand on top of the upper
> bat, and flip the whole thing over. Place the upper bat on the wheel and
> center it on a clay cookie or on some lumps of clay on the wheelhead -
> anything to keep it from slipping around.
>
> Score the circle THOROUGHLY where you want to put the coil. Add PLENTY of
> thick slurry of the same claybody to the scored slurry, but do not score
the
> freshly rolled or extruded coil. Work your fresh coil into place
> thoroughly, so that it displaces all excess slurry. Remove excess slurry,
> throw the coil, trim off excess. Cover the platter overnight to allow the
> moisture content to equalize.
>
> The feet are probably popping off your platters because you are trapping a
> plane of air bubbles in the score marks between the platter and the foot.
> That is a very common problem when no slurry or insufficient slurry is
used.
> Good luck -
> - Vince
>
>
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