Lesley Anton on sun 6 jan 08
Hi all,
Help, help, help!!!
I am trying to find a good porcelain slip casting body and am having
such a time of it. I make lamps - cone 10, some are s porcelain,
some soldate 60. They've always been hand thrown up until now - I
can't keep up with the orders so I've started casting them. I
started using Toshi Porcelain body, from Laguna Clay Co here in CA.
It was fine except for with 2 of my glazes. Of course, my 2 best
sellers. Copper red - it gives a weird purple cast, and one called
Sea Green (oxidation) , which is very translucent, watery green, but
with the Toshi, it gives a blue cast. I suppose the same blue that
comes through on the Copper Red. I switched to "Glacier White"
casting body but it is really weird. Very chippy, and cracks very
easily in the bisque. Even with very prolonged drying periods.
Does anyone have a good porcelain casting body that is pretty
positive universally in it's effects (or lack there of) on cone 10
reduction or oxidation glazes? The ceramic portion of the lamps are
- 15" to 21" tall so sometimes that height is a problem with cracking
on the lower edges but I'd like to find one that has some nice
elasticity and that is white white.
Lesley Anton
www.lesleyanton.com
Lesley Anton on mon 7 jan 08
Thanks John and Michael for the great feedback. I'll try those 2
recipes.
I also wondered - what about a white stoneware casting body? When I
was just throwing, I was using S Porcelain (a Laguna throwing body) ,
which I hear isn't really porcelain, but I got great results for all
of my glazes. We weren't able to deflocculate the powdered form of
S Porcelain for it to cast properly, so I switched to the Toshi porc.
casting body - and that's when I started getting funky glaze
results. But maybe I should have sought out a white stoneware
casting body. Any good recipes for that floating around? I didn't
see any in the archives doing a search - only throwing bodies.
Oh - I found the White Stallion porcelain casting slip recipe , just
in case anyone else wants it - Thanks!!
After reading this recipe though - on the Neodymium oxide issue - the
part about it absorbing yellow light and re-emitting it as blue/
violet/red light - since the problem I am having with the Toshi is
that it gives off a blue cast in 2 of my glazes, that shouldn't be
blue, maybe that Neodymium shouldn't be added? Is that what that
means? can one of you technicians tell me?
Thanks.
White Stallion Porcelain, Fara Shimbo, 2002
35 grolleg
30 Kona F4 (for crystalline glazes) or G-200 feldspar
20 silica
15 EPK
1 part by addition Neodymium oxide.
Using neodymium as a decolorant is a trick I picked up from
glassmakers. Put very simply (more technical infomation
if you ask) neodymium selectively absorbs yellow light and
re-emits it as blue/violet/red light.
White Stallion is very white even without the neodymium,
but with it is so startling white that many people complain
it looks "fake." There's a picture here:
http://crystalline-ceramics.info/ws_with_without_nd.jpg
showing the porcelain without nd on the left and with it on the right.
I use White Stallion both as a casting porcelain and as a
throwing clay. As a throwing clay it's a bit short but as
a casting slip it works fine.
Hope this helps,
Fa
Fara Shimbo, Master Crystalliere, Certified Public Nuisance
-
John Rodgers on mon 7 jan 08
Lesley,
Someone on Clayart - I;m sorry I can't remember who - posted a recipe
for a very, very white porcelain clay body that was called White
Stallion. as I recall . You might do a search in the archives for that
one. it may work for myou.
John Rodgers
Chelsea, aL
Lesley Anton wrote:
> Hi all,
> Help, help, help!!!
>
> I am trying to find a good porcelain slip casting body and am having
> such a time of it. I make lamps - cone 10, some are s porcelain,
> some soldate 60. They've always been hand thrown up until now - I
> can't keep up with the orders so I've started casting them. I
> started using Toshi Porcelain body, from Laguna Clay Co here in CA.
> It was fine except for with 2 of my glazes. Of course, my 2 best
> sellers. Copper red - it gives a weird purple cast, and one called
> Sea Green (oxidation) , which is very translucent, watery green, but
> with the Toshi, it gives a blue cast. I suppose the same blue that
> comes through on the Copper Red. I switched to "Glacier White"
> casting body but it is really weird. Very chippy, and cracks very
> easily in the bisque. Even with very prolonged drying periods.
>
> Does anyone have a good porcelain casting body that is pretty
> positive universally in it's effects (or lack there of) on cone 10
> reduction or oxidation glazes? The ceramic portion of the lamps are
> - 15" to 21" tall so sometimes that height is a problem with cracking
> on the lower edges but I'd like to find one that has some nice
> elasticity and that is white white.
>
> Lesley Anton
> www.lesleyanton.com
>
> ______________________________________________________________________________
>
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
>
Michael Wendt on mon 7 jan 08
Lesley,
Try
Tile #6 25
EPK 25
Feldspar 25
Silica 25
To test this make a 35 lb
batch dry and add it to
15 lbs of water w/3-4 oz
of Darvan in it. Mix, check
specific gravity and add water
only if you can't get the proper
pour out characteristics by
adding small amounts of Darvan
after aging a day or two.
We use Helmer Kaolin for casting
but it is not as white as you want.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
John Rodgers on tue 8 jan 08
Michael,
What do you think could be done with this to make it into a slip casting
body that would mature at Cone 6?
Thanks,
John Rodgers
Chelsea, AL
Michael Wendt wrote:
> Lesley,
> Try
>
> Tile #6 25
> EPK 25
> Feldspar 25
> Silica 25
>
> To test this make a 35 lb
> batch dry and add it to
> 15 lbs of water w/3-4 oz
> of Darvan in it. Mix, check
> specific gravity and add water
> only if you can't get the proper
> pour out characteristics by
> adding small amounts of Darvan
> after aging a day or two.
> We use Helmer Kaolin for casting
> but it is not as white as you want.
> Regards,
> Michael Wendt
> Wendt Pottery
> 2729 Clearwater Ave.
> Lewiston, Id 83501
> U.S.A.
> 208-746-3724
> wendtpot@lewiston.com
> http://www.wendtpottery.com
> http://UniquePorcelainDesigns.com
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
Lesley Anton on tue 8 jan 08
John
Thanks for the suggestion on the B-mix. Oddly enough, I used to use
B-mix for throwing way back but it also (like the Toshi porcelain
casting body) gave me the slight blue cast in my Sea Green glaze
(that is supposed to be just translucent, watery and very almost
grass green. Check out my site (www.lesleyanton.com) - go to the
Lotus table lamp or go to the glazes/shades page to see what the
glaze is supposed to look like.
It worked fine on all of the other glazes - but not that one. My best
selling glaze.
thanks though!
Lesley
John Rodgers on tue 8 jan 08
Lesley,
I do a ton of casting with Laguna's dry bagged B-mix - Cone 5.
If I can get C-5 B-Mix in 50 lb bags dry, I would think you could get
the Cone 10 version dry bagged as well. You might want to check it out.
The B-mix slip performs extremely well. It is pure white as bisque, and
has just and ever so light yellowish cast when fired to maturity. The
use of Neodymium Oxide may alleviate that. Can't say that it will, since
I have not tried it.
Good Luck.
John Rodgers
Lesley Anton wrote:
> Thanks John and Michael for the great feedback. I'll try those 2
> recipes.
>
> I also wondered - what about a white stoneware casting body? When I
> was just throwing, I was using S Porcelain (a Laguna throwing body) ,
> which I hear isn't really porcelain, but I got great results for all
> of my glazes. We weren't able to deflocculate the powdered form of
> S Porcelain for it to cast properly, so I switched to the Toshi porc.
> casting body - and that's when I started getting funky glaze
> results. But maybe I should have sought out a white stoneware
> casting body. Any good recipes for that floating around? I didn't
> see any in the archives doing a search - only throwing bodies.
>
> Oh - I found the White Stallion porcelain casting slip recipe , just
> in case anyone else wants it - Thanks!!
>
> After reading this recipe though - on the Neodymium oxide issue - the
> part about it absorbing yellow light and re-emitting it as blue/
> violet/red light - since the problem I am having with the Toshi is
> that it gives off a blue cast in 2 of my glazes, that shouldn't be
> blue, maybe that Neodymium shouldn't be added? Is that what that
> means? can one of you technicians tell me?
> Thanks.
>
> White Stallion Porcelain, Fara Shimbo, 2002
> 35 grolleg
> 30 Kona F4 (for crystalline glazes) or G-200 feldspar
> 20 silica
> 15 EPK
> 1 part by addition Neodymium oxide.
>
> Using neodymium as a decolorant is a trick I picked up from
> glassmakers. Put very simply (more technical infomation
> if you ask) neodymium selectively absorbs yellow light and
> re-emits it as blue/violet/red light.
>
> White Stallion is very white even without the neodymium,
> but with it is so startling white that many people complain
> it looks "fake." There's a picture here:
>
> http://crystalline-ceramics.info/ws_with_without_nd.jpg
>
> showing the porcelain without nd on the left and with it on the right.
>
> I use White Stallion both as a casting porcelain and as a
> throwing clay. As a throwing clay it's a bit short but as
> a casting slip it works fine.
>
> Hope this helps,
>
> Fa
> Fara Shimbo, Master Crystalliere, Certified Public Nuisance
> -
>
> ______________________________________________________________________________
>
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
>
Michael Wendt on tue 8 jan 08
John,
I think cone 6 casting bodies require
more flux and a lower melting flux.
I would try replacing feldspar with
Nepheline Syenite and increasing the
flux and silica and decreasing the clay
a little at a time until I found a body that
still cast fine but was vitreous at cone 6.
Interestingly, there was a post about
Helios cone 6 where the inquirer said
she was getting warping. I think some
of that may come from the more precipitous
melting point of the lower melting body.
Precise witness cone firing will be essential
with this kind of clay body,
so be sure to test thoroughly.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Jon Pacini on wed 9 jan 08
Greetings All--- Laguna makes casting versions of both ^5 and ^10 B-mixes
S 2830 is the ^10 version and S 2459 is the ^5 version ---Both are generally
in stock at all times.
Best regards,
Jon Pacini
Clay Manager
Laguna Clay Co
Daniel Sommerfeld on wed 9 jan 08
Just a couple thoughts on this discussion.
I've been working on a range of casting recipes for the last couple years -
everything from ultra-white and translucent porcelains to a wood-fired
white stoneware and typical salt-fired stoneware.
I have found in my testing that purity in the porcelain recipe plays a big
role in color development with copper blue/greens (I test with oribe). My
purest bodies will tend towards a blue oribe and the dirtier bodies will
be green. "Dirtier" as in higher iron and titania contents.
The body you couldn't deflocculate probably is rich in bentonite as it
will hinder any attempt to process it.
A typical porcelain recipe is considered:
25 Kaolin
25 Ball Clay
25 Silica
25 Feldspar
Most of the whiter porcelains sub some if not all of the ball clay for
kaolin.
If your clay was not really white then it most likely has a good ball clay
content.
EPK by itself is not a good casting agent (long casts), but I am told it
works well in smaller quantities
Many Ball Clays do not work well in casting recipes due to their particle
size.
Kaopaque settled out over time and glued to the bottom of the bucket (I
may have not had the Darvan calculated properly)
Tile #6 in my tests was also difficult for me to deflocculate and cast
thin. Though it was a nice colored body in the anagama.
I can make a guess that you may want to try:
30 Grolleg
20 Tennessee #1 Ball Clay
25 Silica
25 Feldspar (I use a blend of custer and neph sy)
The silica may be a bit high and the alumina a bit low, but I don't have
any idea of where you are currently
Another way to try it would be to make two distinct batches and mix them
in different percentages to find what you want (a line blend). I
currently have a salt mix that is just a bit dark for my tastes, so I am
planning on doing this to find the best fit).
You may want to try a line blend of these two batches:
50 Grolleg
25 silica
25 Feldspar
and a batch of
50 Tennessee #1
25 silica
25 feldspar
The Grolleg body is quite nice. I don't know how the tennesse body will
work, but I think a blend between the two will be enlightening.
Good luck,
Dan Sommerfeld
www.byhand.us
John Rodgers on wed 9 jan 08
Jon,
As I indicated earlier, I use a lot of S2459 C-5 B-mix in slip
casting. I find it to be an excellent stoneware that has both a parian
whiteness and is very porcelainous in nature. Smooth and easy to work
with. I also use the throwing versions of C5 B-mix.
I had at one time wanted to go eclusively to porcelain, but kept running
into problems that I could only solve with the B-mix. For one thing, I
make slip cast objects and thrown objects and assemble them together. I
could not find a porcelain clay body anywhere that I could so this with
satisfactorily. The B-mix slip clay and the B-mix throwing bodies are
close enough in composition that they work well together. I do a lot of
production - multiples of things - and found that the hassle of
porcelain and it's stickiness on the shelves was problematic. The way I
fire, I can fire B-mix to maturity at cone 5 directly on the shelf with
no kiln wash on the shelves and it works just fine. No stuck pots.
C5 B-mix --- I have used it a very long time. good stuff.
John Rodgers
Chelsea, AL
Jon Pacini wrote:
> Greetings All--- Laguna makes casting versions of both ^5 and ^10 B-mixes
>
> S 2830 is the ^10 version and S 2459 is the ^5 version ---Both are generally
> in stock at all times.
> Best regards,
> Jon Pacini
> Clay Manager
> Laguna Clay Co
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
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