Centa Uhalde on sun 2 may 10
Subject: Slip casting earthenware
For those knowledgeable about the method and who are not opposed to slip
casting as a means of production, I direct this question:
I am trying to push a commercial terracotta slip (04-05) to 02 bisque, whic=
h
the Laguna said should work, then glaze firing to 03. My desire is to have
more chip/break resistant work than is typical for earthenware (is
my logical is off?). I've heard that with earthenware only it is advisable
to bisque higher than the glaze fire.
However, I'm getting cracks in the bisque as well as glaze fire. I'm
thinking it could be related to pushing the slip casting body, or an ill fi=
t
with the 03 glaze (majolica). Is there something I could add to the mix to
make the body less brittle, and/or 1) further test, 2) consult w/ the
manufacturer and have them adjust their secret (half talc) recipe, which
they won't unless it is a large quantity, or 3) find an 03 recipe and make
it myself, in which case can anyone recommend a good terracotta slip castin=
g
body for the higher end range of earthenware? OR, 4) I've considered mixing
cone 6 porcelain slip and earthenware slip, however that could further
complicate the issue rather than simplifying.
Any feedback on any of these options would be appreciated.
Thanks, Centa Theresa
www.centatheresa.com
Centa Theresa
www.centatheresa.com
Lee Love on mon 3 may 10
Centa,
Every clay is different. I fire my Continental Clay terracotta
to cone 012 bisque and cone 1 glaze fire. I sometimes single fire to
cone 1 with terracotta, a clear and an amber glaze.
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Terry Nelson on tue 4 may 10
Centa,
Cracking in your glaze firing might be caused by
quartz inversion
because the terracotta clay is probably vitrified in the bisque to
cone 02. I had this problem refiring porcelain mugs and resolved it
(knock on wood) by slowing down the temperature ramp by a factor of
10 in the range 1030-1130 F.
I'm less sure about the problem when it occurs in the bisque.
Terry
At 11:26 AM 5/2/2010, Centa Uhalde wrote:
>Subject: Slip casting earthenware
>
>For those knowledgeable about the method and who are not opposed to slip
>casting as a means of production, I direct this question:
>
>I am trying to push a commercial terracotta slip (04-05) to 02 bisque, whi=
ch
>the Laguna said should work, then glaze firing to 03. My desire is to have
>more chip/break resistant work than is typical for earthenware (is
>my logical is off?). I've heard that with earthenware only it is advisable
>to bisque higher than the glaze fire.
>
>However, I'm getting cracks in the bisque as well as glaze fire. I'm
>thinking it could be related to pushing the slip casting body, or an ill f=
it
>with the 03 glaze (majolica). Is there something I could add to the mix to
>make the body less brittle, and/or 1) further test, 2) consult w/ the
>manufacturer and have them adjust their secret (half talc) recipe, which
>they won't unless it is a large quantity, or 3) find an 03 recipe and make
>it myself, in which case can anyone recommend a good terracotta slip casti=
ng
>body for the higher end range of earthenware? OR, 4) I've considered mixin=
g
>cone 6 porcelain slip and earthenware slip, however that could further
>complicate the issue rather than simplifying.
>
>Any feedback on any of these options would be appreciated.
>
>Thanks, Centa Theresa
>www.centatheresa.com
>
>
>
>
>
>Centa Theresa
>www.centatheresa.com
Terence J. Nelson
167 Maple St.
New Providence, NJ 07974
(908) 464-1652 (fax -0149)
terry@tjnelson.com
tjn512@gmail.com
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