John Rodgers on sun 29 jan 06
Has anyone ever done this with success?
I have a challenge. I have need to throw one piece and cast the
accompanying piece. I need to use the same clay, essentially, to do
both pieces. I've done a lot of things with clay, but never this. Is it
possible?? If so, how so??
This set is to be in porcelain, and I am using Standards Grolleg C-6. If
anyone has any experience in making a slip casting clay from a standard
(small "s") throwing body, I would appreciate hearing from you.
Thanks,
Regards,
John Rodgers
Chelsea, AL
Kathy McDonald on sun 29 jan 06
John ..
I have never had any success with this,
except for small decorative additions to lids.
I seem to get the clay over flocculated.
So I opted to look for a commercial casting slip that works with my clay.
I use a grolleg porcelain at c 10 for
a lot of specialty pots and the closest thing i've been able to match
for cast pieces is a cone 10 casting slip from Pottery Supply
House in Ontario. Works like a charm, attaches well to my porcelain
throwing
body ( Tucker's HHP) at the semi leather hard stage and shrinks about the
same amount.
Glazes work well.
This stuff is fine for small projects or a run of a small number of cast
pieces but is too expensive for me to use otherwise because I am paying
for shipping the liquid slip and if the pieces are poured I often have to
pay someone to clean their normal equipment to pour them for me so they can
do c 10
slip.
It's been a while since I ordered this stuff, and I notice their
link is not working so I don't know if they are still making it.
Kathy
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of John Rodgers
Sent: Sunday, January 29, 2006 6:32 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Convert throwing clay to slipcasting clay
Has anyone ever done this with success?
I have a challenge. I have need to throw one piece and cast the
accompanying piece. I need to use the same clay, essentially, to do
both pieces. I've done a lot of things with clay, but never this. Is it
possible?? If so, how so??
This set is to be in porcelain, and I am using Standards Grolleg C-6. If
anyone has any experience in making a slip casting clay from a standard
(small "s") throwing body, I would appreciate hearing from you.
Thanks,
Regards,
John Rodgers
Chelsea, AL
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Fredrick Paget on sun 29 jan 06
>Has anyone ever done this with success?
>
>I have a challenge. I have need to throw one piece and cast the
>accompanying piece. I need to use the same clay, essentially, to do
>both pieces. I've done a lot of things with clay, but never this. Is it
>possible?? If so, how so??
>
>John Rodgers
You can do this but the slip will be very slow , that is requires a
long time in the mold to build up to thickness. That is compared to a
real casting slip. Can be hours.
I do this by taking totally bone dry clay body and make a slip of it
by placing it in a minimum amount of water and leave it stand without
stirring until it slakes down, This takes time . If you use clay body
that is crushed to a fine size it goes faster. It should be like mud
that is very wet but not liquid. Then defloculate it by adding a
small amount of Darvan and stir it up. It should liquify. You can add
a little more Darvan but be careful not to use too much or it can
thicken up if over deflockulated. You may have to add a little water
too. At this point you can strain it to get out any lumps or junk.
Pour into the mold and there you go.
--
From Fred Paget,
Marin County, CA, USA
fredrick@well.com
http://homepage.mac.com/fredrick/FileSharing1.html
Charter Member Potters Council
Martin Kastner on mon 30 jan 06
We have done this with English porcelain from Laguna. They sell the clay both wet and dry, we
bought the dry mix and made slip as usual (Darvan 811 as deflocculant). It performed fine,
comperable to standard slips I have used. I assume this would be the case with most clays.
Martin
May Luk on mon 30 jan 06
Hello John;
My casting slip recipe is 25 kg dry clay, 10 g Sodium Silicate, 10 g
soda ash. Mix with a drill / paint mixer. I don't know how much water to
add. I learnt by eye-balling. I have done this with white earthenware,
terra cotta and non-groggy stoneware.
A mug took about 30-40 minutes. Of course you have to test and time for
your clay. I have not done this with porcelain, but the theory is the same.
Regards
May
Lee Love on mon 30 jan 06
On 2006/01/30 3:50:22, fredrick@well.com wrote:
> I do this by taking totally bone dry clay body and make a slip of it
> by placing it in a minimum amount of water and leave it stand without
> stirring until it slakes down, This takes time . If you use clay body
> that is crushed to a fine size it goes faster.
I have mentioned this before. At my clay store back home, Continental
Clay, you could buy clay bodies dry. I used to use dry claybody to dry
out reclaim. I also used the dry SuperWhite to make slip out of for hakame.
--
李 Lee Love 大
愛 鱗
in Mashiko, Japan http://mashiko.org
http://seisokuro.blogspot.com/ My Photo Logs
http://ikiru.blogspot.com/ Zen and Craft
"The way we are, we are members of each other. All of us. Everything.
The difference ain't in who is a member and who is not, but in who knows
it and who don't."
--Burley Coulter (Wendell Berry)
Bonita Cohn on mon 30 jan 06
Hi _ Your best bet is to get your clay body into dry
powder form.( - either buy it or dry it out and refine
it.)
Use this as the base for your casting slip which will
be more sodium silicate than water. and stirred almost
constantly. There are recipes - in Val Cushing's
Handbook, and probably in the archives...I could dig
one up from my copy of the Anderson Ranch Handbook (
an old copy pf pre-computer handouts from the
workshops.) But this will take some time....
Good luck.
Bonita in San Francisco.
Ist Calla lilly is blooming and one rose.
Happy CHinese New Year!
< I need to use the same clay,
> essentially, to do
> both pieces.
Bonita Cohn
http://www.bonitacohn.com
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Bill on tue 31 jan 06
John,
It can be done, provided that your throwing body doesn't contain bentonite.
Here is how I'd do it (and have done it in the past).
1. Start with 1000 grams of plastic clay body. (That is about 200 grams of water and 800 grams
of clay.)
2. Put 200 grams of water in a container.
3. Add 3 grams of Darvan 7 to the water.
4. Mix very aggressively with some sort of mechanical mixer (milk shake mixer, blender, jiffy
mixer chucked in a drill, etc.)
5. Slowly add the plastic clay while mixing. It doesn't look like it will fit but you will be surprised.
6. When it gets too thick, add a little more Darvan, but don't add more than another 3 grams (6
grams total, which is 0.75% of the dry clay).
This will give you about 700 ml of slip if you can get all the clay to go in. (It won't all fit if you use
a milk shake mixer or a blender, so you will need to cut all the amounts in half.)
If it works, and the slip is nice and fluid, try again with less water in the container to start out.
(100 grams of water will be about the lower limit.) Casting slips work best after they have aged 24
hours.
Sodium silicate works well too, but there is more danger of over-deflocculating.
Keep notes so next time you know how much clay, Darvan and water to use.
-Bill
On Sun, 29 Jan 2006 06:32:23 -0600, John Rodgers wrote:
>Has anyone ever done this with success?
>
>I have a challenge. I have need to throw one piece and cast the
>accompanying piece. I need to use the same clay, essentially, to do
>both pieces. I've done a lot of things with clay, but never this. Is it
>possible?? If so, how so??
>
>This set is to be in porcelain, and I am using Standards Grolleg C-6. If
>anyone has any experience in making a slip casting clay from a standard
>(small "s") throwing body, I would appreciate hearing from you.
>
>Thanks,
>
>Regards,
>
>John Rodgers
>Chelsea, AL
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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