PeteTree@AOL.COM on thu 18 jul 02
I'm trying to get used to throwing a very soft porcelain body. I can do ok
on small stuff, but anything getting bigger that 6" or so, it ether develops
a wobble, or just collapses. Am i missing something? I'm used to a pretty
stiff stoneware, but this is a whole different ball game. ANY help/tips
would be appreciated.
Peter
Patrick Rowe on fri 19 jul 02
I buy a porcelain that is also very soft. I take it out of the bag, cut the
block into quarters and let it dry out for a day or two. If it gets a
little too stiff, I just wedge in some straight from the bag.
Patrick
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of PeteTree@AOL.COM
Sent: Thursday, July 18, 2002 6:03 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Throwing a soft clay body
I'm trying to get used to throwing a very soft porcelain body. I can do ok
on small stuff, but anything getting bigger that 6" or so, it ether develops
a wobble, or just collapses. Am i missing something? I'm used to a pretty
stiff stoneware, but this is a whole different ball game. ANY help/tips
would be appreciated.
Peter
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william schran on fri 19 jul 02
Peter wrote: "I'm trying to get used to throwing a very soft
porcelain body. I can do ok on small stuff, but anything getting
bigger that 6" or so, it ether develops a wobble, or just collapses."
With porcelain you will have to learn to thrown faster (not spend so
much time centering and creating the basic form) so as not to add
excess water and/or thrown drier. You have also encountered the need
for minimal contact between hands/tools and the clay body. You want
to encourage the porcelain - not force it. You can get away with a
lot more abuse with a raku body, but porcelain will react to the
slightest touch.
You can also roll out the clay into thick coils, curve them and stand
up to look like croquet hoops until it has stiffened up to your
liking.
Julie Milazzo on fri 19 jul 02
Either use little to no water (use for centering,
nothing else), and throw really slowly, or switch to
one of the more plastic porcelains, like Highwater's
P-10, or Laguna's Glacia. Same look, but more fun than
trying to throw toothpaste. Jules
--- PeteTree@AOL.COM wrote:
> I'm trying to get used to throwing a very soft
> porcelain body. I can do ok on small stuff, but
> anything getting bigger that 6" or so, it ether
> develops a wobble, or just collapses. Am i missing
> something? I'm used to a pretty stiff stoneware, but
> this is a whole different ball game. ANY help/tips
> would be appreciated.
>
> Peter
>
>
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> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change
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> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be
> reached at melpots@pclink.com.
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Philip Poburka on fri 19 jul 02
Dear Peter,
I am sure there are better solutions than mine had been, but when I would
run into this, I would throw only so far...let it sit - over to the side,
while I worked on other things - and return to it when it had 'dried' a
little, and was not so soft.
As, depending on what I was intending the thrown peice to be, I would throw
a thick stubby cylinder say...then pull it into the Bowl or what I was
after...having kept the section fairly even for it to sit and 'dry' as...
Sometimes the only Clay I had was too soft, and that was frustrateing to the
urge to be seeing forms get 'done'...but the setting aside let me bring up a
series of things, so I felt I were getting somewhere afterall...and I was
too!
Phil
Las Vegas...
----- Original Message -----
From:
To:
Sent: Thursday, July 18, 2002 3:03 PM
Subject: Throwing a soft clay body
> I'm trying to get used to throwing a very soft porcelain body. I can do ok
on small stuff, but anything getting bigger that 6" or so, it ether develops
a wobble, or just collapses. Am i missing something? I'm used to a pretty
stiff stoneware, but this is a whole different ball game. ANY help/tips
would be appreciated.
>
> Peter
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Bruce Girrell on fri 19 jul 02
> I'm trying to get used to throwing a very soft porcelain body. I
> can do ok on small stuff, but anything getting bigger that 6" or
> so, it ether develops a wobble, or just collapses.
Many of the forms that I throw using porcelainous clay would fall into the
category of closed forms. The largest diameter is close to 12 inches with an
opening just large enough to squeeze my hand into at the top. These forms
almost always want to collapse because of the large unsupported distance.
Email me directly if you want and I'll send you a photo of what the shapes
look like.
In many cases I stop throwing when I detect imminent collapse and either
wait for the clay to stiffen or else use a blowtorch to dry the clay enough
to continue. After drying the clay like this I usually work dry which also
entails slowing down the wheel a bit. Sometimes I'll just put a piece of
plastic over the thing and come back to it the next day.
The only other option that I have found is to throw thick enough that the
clay can support the form that you're trying to make, then trim to the
finished thickness. For all its quirks, porcelain is very cooperative in the
trimming process. Use a sharp tool.
Bruce "the trimmin' fool" Girrell
Ron Roy on sat 20 jul 02
Hi Peter,
Yes - porcelain is not the best for throwing - usually only 50% clay so it
wets quickly.
You need to get good at throwing - try one pull cylinders and cut them in
half - you can see where you need to concentrate pressure - when you can
get it even with one pull do two - until you can get the walls even. Use
slip instead of water and put it where you need it (like not at the rim)
and only use a much as you need - no more.
Most porcelain is trimmed thin so - throw the inside the shape you want and
trim the excess off.
The white burning porcelains are the worst - no ball clay to help with
throwing.
Aged porcelain is much better by the way - best to mix in some old clay to
new and let it sit around in a warm place for a month or so - big
difference!
Some porcelains become deflocced - no use trying to throw them - if you
suspect that try adding some vinegar - say a spoon full to 5 lb to see if
it's deflocced. If it is you will have to start adding some Epsom salts to
the mix - 2lb (dissolved in very hot water) to 1000 lb of dry mix or have
your supplier do it.
RR
>I'm trying to get used to throwing a very soft porcelain body. I can do ok
>on small stuff, but anything getting bigger that 6" or so, it ether
>develops a wobble, or just collapses. Am i missing something? I'm used to
>a pretty stiff stoneware, but this is a whole different ball game. ANY
>help/tips would be appreciated.
>
>Peter
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
iandol on sat 20 jul 02
Dear Peter,
You do not say what you are doing about lubrication while you are =
throwing, the weight of clay you are using or the height you intend =
achieving.
If your Porcelain clay is of the usual type with a high proportion of =
none plastic materials which has had its plasticity enhanced with =
additions of Bentonite or similar Montmorillonite clay then it is =
advisable to eliminate all forms of lubrication as soon as you have =
achieved the essential tasks of centring and opening.
With a good plastic stoneware I would suggest using slip as a lubricant =
but it sounds as though you have more than enough water in your clay. So =
I would eliminate anything which would supply water which will be =
adsorbed by the Bentonite. This brings you back to using a "Dry Throwing =
Technique", as described by Leon Nigrosh in his book "Claywork".
Some of additive plasticisers can adsorb up to ninety percent of their =
own volume of water. They are know as "Expanding Clays". Given this as a =
fact it is easy to see that such a clay will loose it's mechanical =
integrity and fail to support its own weight once the wall has been =
reduced in thickness towards the base.
Unless you have a good reason for throwing very soft clay I would allow =
it to firm up, or alternatively alter your technique as suggested if you =
intend getting superior elevation.
Best regards
Ivor Lewis,
Redhill, South Australia.=20
Tom and Jean Latka www.ceramicsite.com on mon 22 jul 02
The advice I receive from Michael Cardew ( I don't drop name to impress =
just to site the source) gave me about throwing was to use soft clay. I =
use soft clay is because it is easier to center when using it to throw, =
thus making the process less labor intensive. My theory why many =
potters have carpel tendril (don't know if spelled correctly) is because =
they buy clay from suppliers and most of the clay is hard. I recently =
retired my clay mixer because I found out Laguna Clay (I am sure there =
are other clay suppliers as well) will make my body as soft as I would =
like. I would encourage any one who makes a lot of pots to consider =
using soft clay. A reason that potters have trouble using an extruder =
is because the clay is to hard. If you use clay for sculpture use soft =
clay. The less work you have to do from the technical side, the better.
Speaking of clay. Has anyone used Buff Sculpture WC 392 clay from =
Laguna?
Cheers,
When responding please include our names Tom or Jean in SUBJECT LINE
Tom Latka
229 Midway
Pueblo, Co. 81004
719-543-0720
fax 719-543-3081
latka@fone.net
http://www.ceramicsite.com
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