Jesse Hull at Wiseman Ceramics on thu 3 apr 08
Anyone have any knowledge on slip-casting small SOLID porcelain forms?
I've come across little figurines and the like that I assume are made in
this way, as I've even found seam lines on those made with 2 & 3-part molds.
These could perhaps be made using hand & ram-press methods, but some of
these were as large as 6-7", and it would seem that those made from the
3-part molds might be quite cumbersome to press a shape out of.
In any event, I'm hoping to make small (around 3"x3") forms by slip-casting,
and am wondering if it can be done.
These would be simple cone shapes with no real detail, so I would be
employing a 1-part mold. I would guess that one would need to make the
plaster wall thicker?
What I'm mostly concerned with is how to make the porcelain slip perform
better under the conditions that must be met in making a solid form and
avoid gelling, cracking, etc.
Any thoughts or experience based tips would be greatly appreciated.
~jesse.
James O'Brien on sat 5 apr 08
you can cast solid as long as you dont have any undercuts in your mold. If
an upper part of your mold is smaller than any lower part it will seal off
the lower part and slip cant get in to make it solid. As the part dries, it
will create a vacuum and crack. You can even cast a cylinder with straight
sides in a one piece mold and as the part shrinks and it will release.
Gelling is not a problem with a properly deflocculated slip. If you want to
know how far you can go, fill a plastic bucket with slip and let it sit for
a week. You will have a solid block of clay. It wont be flat on top but it
will be solid. 1" wall thickness should be plenty. The real key is slip
quality and time.
James
On Wed, Apr 2, 2008 at 11:12 PM, Jesse Hull at Wiseman Ceramics <
wisemanceramics@yahoo.com> wrote:
> Anyone have any knowledge on slip-casting small SOLID porcelain forms?
>
> I've come across little figurines and the like that I assume are made in
> this way, as I've even found seam lines on those made with 2 & 3-part
> molds.
> These could perhaps be made using hand & ram-press methods, but some of
> these were as large as 6-7", and it would seem that those made from the
> 3-part molds might be quite cumbersome to press a shape out of.
>
> In any event, I'm hoping to make small (around 3"x3") forms by
> slip-casting,
> and am wondering if it can be done.
> These would be simple cone shapes with no real detail, so I would be
> employing a 1-part mold. I would guess that one would need to make the
> plaster wall thicker?
> What I'm mostly concerned with is how to make the porcelain slip perform
> better under the conditions that must be met in making a solid form and
> avoid gelling, cracking, etc.
>
> Any thoughts or experience based tips would be greatly appreciated.
>
> ~jesse.
>
>
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