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converting casting slip to throwing consistency

updated fri 31 mar 06

 

John Rodgers on tue 28 mar 06


I have quite a number of one gallon plastic bottles of porcelain slip
that I would like to make up into a throwing body. The labels are gone,
but I do know that it is porcelain from some supply house that makes
porcelain slip. It works great for slip casting. But I have need to make
it into a throwing body.

Has anyone ever done this? - convert porcelain slip to a solid clay body
for throwing on a wheel? Porcelain slip allowed to solidify to a solid
clay mass is not plastic enough and needs something added, but I know
not what. When I knead the clay it does not yield and stretch the way a
normal throwing body does, but instead it fractures. Has anyone any
suggestions about how to go about making this conversion? Anyone know of
any kind of polymer or something to use as an additive? A little
bentonite perhaps? I'm just fishing here.

Thanks,

John Rodgers
Chelsea, AL

Kathy McDonald on tue 28 mar 06


John does this have to be exactly the same composition, or
can it be
a bit different?

I have a good friend who is a doll maker and she and her
husband
run a fairly large supply business. She cannot reuse any of
her
recycled slip and from time to time they have "bad" batches
that
I have inherited. It is almost always cone 6.

The only solution that that ever worked for me has been to
wait until I have enough cone 6 B mix reclaim and use equal
parts
by liquid volume( I did get a viscometer) and add about 2%
bentonite and a bit of vinegar. Then it has to age in pails
to set up (covered).
suspect the cone 6 BMix has enough plastic clay in it to
make the
clay work as a throwing body. I make my tiles out of the
slip
and I don't notice any real difference in the glazes on the
surface
of the two different types of clay. (ie plain b/mix and
porcelain/bmix)
If anything I think the glazes might be a bit better on the
mixture
of the two.

The process takes about 6 months. It's still a bit short
when wedging
but a friend said to use some glycerin on my hands and that
does seem to
make it workable. It's not great for throwing large bowls
or tall pieces
but works as well as any c 6 stoneware that I've used for
mugs and the like.

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of
John Rodgers
Sent: Tuesday, March 28, 2006 12:08 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Converting Casting Slip to Throwing Consistency


I have quite a number of one gallon plastic bottles of
porcelain slip
that I would like to make up into a throwing body. The
labels are gone,
but I do know that it is porcelain from some supply house
that makes
porcelain slip. It works great for slip casting. But I have
need to make
it into a throwing body.

Has anyone ever done this? - convert porcelain slip to a
solid clay body
for throwing on a wheel? Porcelain slip allowed to solidify
to a solid
clay mass is not plastic enough and needs something added,
but I know
not what. When I knead the clay it does not yield and
stretch the way a
normal throwing body does, but instead it fractures. Has
anyone any
suggestions about how to go about making this conversion?
Anyone know of
any kind of polymer or something to use as an additive? A
little
bentonite perhaps? I'm just fishing here.

Thanks,

John Rodgers
Chelsea, AL

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Ron Roy on thu 30 mar 06


Hi John,

I assume that slip is deflocced - it should be for casting - if so you will
not be able to throw with it unless you can find a way to flocculate it. If
you do that you will probably wind up with a scumming problem.

RR

>I have quite a number of one gallon plastic bottles of porcelain slip
>that I would like to make up into a throwing body. The labels are gone,
>but I do know that it is porcelain from some supply house that makes
>porcelain slip. It works great for slip casting. But I have need to make
>it into a throwing body.
>
>Has anyone ever done this? - convert porcelain slip to a solid clay body
>for throwing on a wheel? Porcelain slip allowed to solidify to a solid
>clay mass is not plastic enough and needs something added, but I know
>not what. When I knead the clay it does not yield and stretch the way a
>normal throwing body does, but instead it fractures. Has anyone any
>suggestions about how to go about making this conversion? Anyone know of
>any kind of polymer or something to use as an additive? A little
>bentonite perhaps? I'm just fishing here.
>
>Thanks,
>
>John Rodgers
>Chelsea, AL
>
>______________________________________________________________________________
>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.

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0