Porscha' B on thu 11 aug 05
Hello,
i have some plaster body cast molds that i wish to slip cast with raku, is
that possible?
i found your email from a conversation posted on the internet.. could you
give me a recipe or hints.. i know little about ceramics, just body casting
and the raku firing process.. is it possible to do raku slip casting? like
for the whole piece, not just glazing? please get back to me, i would
greatly appreciate it :)
peace and unity
-porscha'
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Snail Scott on fri 12 aug 05
At 07:51 PM 8/11/2005 -0800, you wrote:
>...have some plaster body cast molds that i wish to slip cast with raku, is
>that possible?...is it possible to do raku slip casting? like
>for the whole piece, not just glazing?
It is certainly possible to raku a slip-cast piece.
Note that the biggest hazard will be the stresses
caused by unequal heating of such a large object.
The chances of breakage are quite high. To improve
your chances, use a mid-range (cone 6) casting slip,
and add 20% powdered kyanite. This may help with
the thermal-shock problems. It will still be a
challenge to get it fired in one piece, though.
The fragments could be glued, of course, but this
may or may not be compatible with your idea.
You mentined that raku is the only ceramic process
you're familiar with. So, I'll ask: is it important
that the piece be raku fired, and have a raku look?
A 'normal' kiln firing (without the huge stresses of
raku) will increase your chance of a successful,
one-piece result. You won't get the zippy metallic
glaze effects of raku, but if that's not critical,
you could still get a very nice (though different)
piece.
Since you have a mold, consider making several
versions, each glazed and fired differently. Don't
do just one, especially if you'll be terribly
disappointed by a bad outcome.
-Snail
Leland Hall on fri 12 aug 05
Hi,
The short answer is "yes, it is possible to raku fire slip cast ware".
Laguna Clay Co. at one time sold a "raku slip", for just this. However I
don't know if they still do.
On the other hand, you may try raku firing regular slip cast ware, though
you may find that there is much loss due to thermal shock. I suggest
trying a lower bisque if you try it that way.
Many years ago, I developed a raku slip for casting simply by slaking down
some bagged clay. The clay we used had a sand content, and we had trouble
with the sand settleing, but as I recall we worked it out. This was a long
time ago, and I don't remember many details. Our next experement was with
a kyanite bearing raku clay, and it worked better.
I suggest you contact Laguna Clay, and see if they still manufacture the
raku slip. We never tried it, as we haven't been into slip casting for
quite a few years.
Good luck and have fun
Leland Hall
Before The Wheel Enterprises
Raku Pottery and Sculpture
La Pine, Oregon
On Thu, 11 Aug 2005 19:51:47 -0800, Porscha' B wrote:
>Hello,
> i have some plaster body cast molds that i wish to slip cast with raku,
is
>that possible?
>i found your email from a conversation posted on the internet.. could you
>give me a recipe or hints.. i know little about ceramics, just body casting
>and the raku firing process.. is it possible to do raku slip casting? like
>for the whole piece, not just glazing? please get back to me, i would
>greatly appreciate it :)
> peace and unity
> -porscha'
Craig Clark on fri 12 aug 05
Porscha' B wrote:
> Hello,
> i have some plaster body cast molds that i wish to slip cast with
> raku, is
> that possible?
> i found your email from a conversation posted on the internet.. could you
> give me a recipe or hints.. i know little about ceramics, just body
> casting
> and the raku firing process.. is it possible to do raku slip casting?
> like
> for the whole piece, not just glazing? please get back to me, i would
Porscha, I'm not sure but I don't think you really understand what
Raku is from your question. If you want to slip cast you will need to
use a properly formulated slip. You will then pour that slip into your
mold. You will Raku Fire your slip cast piece. This is not only possible
but has been done by a goodly number of folks. If you use a slip for
your pieces just make sure that you have enough grog or kyanite in the
slip so that the pieces will survive the thermal shock of the raku process.
I have been doing body castings for a while now, using both plaster
and alginate. What has worked for me is to press soft slabs of raku clay
into the molds. I use Lagunas WSO clay body, as well as the Paper Clay
Sculpture Body (white) from Axner, the raku body from Armadillo Clay in
Austin Texas, and my own special blend which is occassionally mixed by
my rapidly aging back in a Soldner Mixer at me old alma mater. The
recipe is one 100 lb bag of Hawthorn Bond, one 50 lb bag of Gold Art,
one 50 lb bag of Ball Clay and grog/kyanite to taste. I put a minimum of
15% grog or kyanite in the mix and go to 25% by weigth if the clay is
for larger pieces. I mix it soft!!!! Learned this from all of the
wonderful folks on CLayArt.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
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