Dave Finkelnburg on wed 13 sep 06
Ivy,
Yes, any clay can be made into a casting slip.
Whether it's a good casting slip...well...depends!
:-)
Non-plastic materials in a clay body make it
somewhat porous, which makes the body better for
casting--water can get out of the body and into the
absorbent mold.
The deflocculant allows one to make a relatively
fluid slip that contains a near-minimum amount of
water. The less water in the slip the quicker the
walls build and the faster the casting forms in the
mold.
A good casting slip may only contain 35% clay. A
typical stoneware for throwing, in contrast, is 85%
clay.
Good potting!
Dave Finkelnburg
--- Ivy Glasgow wrote:
> This brings two questions to mind. Can just any clay
> be made thixotropic by
> this approach, or are there some which don't respond
> to treatment with a
> deflocculant? And, could just any clay be made into
> a casting slip?
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Des & Jan Howard on thu 14 sep 06
Dave
How's this for an atypical stoneware!
Our grey porcelaneous stoneware body consists of:
10% of a local altered rhyolite, ( by itself is like trying to throw a
block of cheddar cheese)
60% of a local earthy material, (plasticity of a lump of wet feldspar,
XRD analysis shows it to be quartz/illite/muscovite/dickite)
30% of a local plastic kaolin.
The combination throws/jiggers/extrudes/presses like a dream, self
burnishes during turning.
Des
Dave Finkelnburg wrote:
> A good casting slip may only contain 35% clay. A
>typical stoneware for throwing, in contrast, is 85%
>clay.
> Good potting!
>
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
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