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hump mold thought, was re: slipware plates

updated fri 14 jan 05

 

Kate Johnson on wed 12 jan 05


> At 01:06 PM 1/12/2005 -0600, you wrote:
>>In that case I'd think you'd need to put it over the mold while it
>>was softer than leather-hard in order to pick up the design, pressing it
>>gently over the mold, then being careful to remove the clay at the correct
>>time to prevent cracking at is dries...
>
>
> If it's a bit stiffer when put over the mold,
> it has less shrinkage remaining in it, and the
> removal can be later (and stiffer) as well.
> (Not too stiff, though - it's gotta be able to
> move its particles around when laid onto the
> mold.)

Hi Snail!

Well, coincidentally, just got my new copy of Ceramics in America which
addresses this very issue! The clay being pressed onto this kind of mold
looks still quite soft, and they BANG it on the back to push it into the
carving...
>
> As for pressing gently, I'd do the opposite -
> really force that slab down ferociously, all
> over. The more you move the clay, the less
> likely it'll sag back to its old flat self.

I think you're right! Well...anxious to try THIS now...

I was just incising an edge on one of the slump molds I made last night so I
can either trim even with the top or allow for a rim and trim there, and saw
how easy it would be to incise a design into a plaster form...looking at
mold forms online, though, and they seem a bit steep, so will probably make
my own again, from clay.

Thank you, as always!

Best--
Kate

Kate Johnson on wed 12 jan 05


Meg wrote:
> The "old timers" actually did these plates a third way - slip trailing
> and feathering on the flat discs, letting them firm up and then flipping
> them upside down on a hump mold rather than in a bowl-like mold -

Another similar technique involved laying your sheet of clay over a hump
mold that had a design impressed into it, like the sun face plates on the
Ceramics in America, or like the 1750s man in one of the books I have.

_Naturally_, I want to try this, too, when I can spare the clay to make a
bisque mold (since that's what "they" used.) (Waiting for an order
now...) In that case I'd think you'd need to put it over the mold while it
was softer than leather-hard in order to pick up the design, pressing it
gently over the mold, then being careful to remove the clay at the correct
time to prevent cracking at is dries.

Anyone tried this one?

I think I need to apprentice to someone who's been dead a couple of
centuries...

Best--
Kate

Snail Scott on wed 12 jan 05


At 01:06 PM 1/12/2005 -0600, you wrote:
>In that case I'd think you'd need to put it over the mold while it
>was softer than leather-hard in order to pick up the design, pressing it
>gently over the mold, then being careful to remove the clay at the correct
>time to prevent cracking at is dries...


If it's a bit stiffer when put over the mold,
it has less shrinkage remaining in it, and the
removal can be later (and stiffer) as well.
(Not too stiff, though - it's gotta be able to
move its particles around when laid onto the
mold.)

As for pressing gently, I'd do the opposite -
really force that slab down ferociously, all
over. The more you move the clay, the less
likely it'll sag back to its old flat self.

-Snail