Keramik Burger on sun 28 apr 02
Hallo,
I read in the archivs but I dit not find to much about the solving of my
problem.
I made a porcelain slip (58% Kaolin, 22% Feldspar, 18% Silica, 2%
Bentonite, 0,2% Tusil(defolc.), 43 % Water)
I fire it at cone 9 (Seger-cone)
The density is 1,8 kg/ liter.
After about 2-3 Minutes the wall is about 3-4 mm thick. But even if all the
clay feels dry it does not get of the mold.Not even
after one day.
I tried a lot of things, but for I do not realy know a lot about
slip-casting I did probably many silly things.
Where should I continue?
I made tests for about two weeks now. I also tried with more Bentonite(up
to 5 %), a littel Ball Clay..(only up to 5%).
The mold is selvemade, but I used a ready bought mold too to test my modl-
the same result...
ciao
Ralf
Ralf Burger on sun 28 apr 02
Hallo,
I read in the archivs but I dit not find to much about the solving of my
problem.
I made a porcelain slip (58% Kaolin, 22% Feldspar, 18% Silica, 2% Bentonite,
0,2% Tusil(defolc.), 43 % Water)
I fire it at cone 9 (Seger-cone)
The density is 1,8 kg/ liter.
After about 2-3 Minutes the wall is about 3-4 mm thick. But even if all the
clay feels dry it does not get of the mold.Not even
after one day.
I tried a lot of things, but for I do not realy know a lot about
slip-casting I did probably many silly things.
Where should I continue?
I made tests for about two weeks now. I also tried with more Bentonite(up to
5 %), a littel Ball Clay..(only up to 5%).
The mold is selvemade, but I used a ready bought mold too to test my modl-
the same result...
ciao
Ralf
Geoffrey Shilling on sun 28 apr 02
I use earthenware slip and have not had any trouble with the piece releasing
from the molds but I have heard that talc works well. For porcelain though,
silica is supposed to be better. Just dust a little in the mold. Hope this
helps.
- Geoffrey -
Longtin, Jeff on mon 29 apr 02
Ralf,
As previously mentioned the dusting technique may be your answer. You may
also want to try wetting the mold. You can do this by holding the mold under
a faucet of running water. Essentially re-wetting it.
As the mold drys from its initial pouring the plaster pores remain in a
closed state. Their absorption is not as great as it can be. By re-wetting
the mold you create a situation whereby all the pores can open up
completely.
I also know porcelain doll artists who like to wet their molds every time
before they pour. They claim this too prevents sticking.
My only other suggestion would be to buy some commercial stuff and see how
that works, as a comparison. Years ago I struggled with mixing my own
porcelain slip but found it to be too much the nightmare. I pour stoneware
as a result.
Good Luck
Jeff Longtin
Always happy to share information. Life is too short.
-----Original Message-----
From: Ralf Burger [mailto:ralf@FEUER-TOEPFER.DE]
Sent: Sunday, April 28, 2002 1:36 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: slip sticks to mold
Hallo,
I read in the archivs but I dit not find to much about the solving of my
problem.
I made a porcelain slip (58% Kaolin, 22% Feldspar, 18% Silica, 2% Bentonite,
0,2% Tusil(defolc.), 43 % Water)
I fire it at cone 9 (Seger-cone)
The density is 1,8 kg/ liter.
After about 2-3 Minutes the wall is about 3-4 mm thick. But even if all the
clay feels dry it does not get of the mold.Not even
after one day.
I tried a lot of things, but for I do not realy know a lot about
slip-casting I did probably many silly things.
Where should I continue?
I made tests for about two weeks now. I also tried with more Bentonite(up to
5 %), a littel Ball Clay..(only up to 5%).
The mold is selvemade, but I used a ready bought mold too to test my modl-
the same result...
ciao
Ralf
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