JRodgers on mon 9 jul 12
I've been slip casting a long time, but I have tun up on a problem that
has me baffled.
My slipcasting clay is Laguna C-5 B-mix. Comes dry in 50 lb bags. Have
been using it for years. I have a tank of slip that has been cast,
excess and scraps recovered and remixed several times, adjusted and the
numbers are right on - density of 1.75, viscosity rate 24 seconds with
my viscosity cup which is dead on. Then, after making a production run,
and doing the recovery thing, on the next round - my clay is flat.
Properly adjusted, but it will not set up in a normal time frame, and in
the normal time frames for each mold, the clay walls are very thin. What
normally would be a 1/4 inch wall thickness in one hour - is far less in
three hours. Then, after emptying the molds, and allowing for setting up
of the new shell - upon opening the molds - the clay is stuck to the
molds and the piece is torn apart - on every single mold. I am stumped.
The only variable I can think of is that I used sodium silicate from a
new bottle, instead of the from the old bottle. The source of the new is
different than the old, but the viscosity appears the same, and they are
both clear.
If anyone has any insight into this problem, I would appreciate hearing
about it. I've got a gallery showing in three weeks and I have got to
get this problem licked.
Thanks,
John
John Britt on tue 10 jul 12
John,
I would ask Jonathan Kaplan. Could your molds be degrading?
John Britt Pottery
James Freeman on tue 10 jul 12
John...
I remember reading in one of my books that casting slip should never
contain more than a small percentage of reclaim. I think the number was
25%. I don't recall why, but I do recall that it made sense to me at the
time. I will try to locate the reference if I have time this afternoon.
Take care.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Jul 9, 2012 at 10:52 PM, JRodgers wrote:
> I've been slip casting a long time, but I have tun up on a problem that
> has me baffled.
>
> My slipcasting clay is Laguna C-5 B-mix. Comes dry in 50 lb bags. Have
> been using it for years. I have a tank of slip that has been cast,
> excess and scraps recovered and remixed several times, adjusted and the
> numbers are right on - density of 1.75, viscosity rate 24 seconds with
> my viscosity cup which is dead on. Then, after making a production run,
> and doing the recovery thing, on the next round - my clay is flat.
> Properly adjusted, but it will not set up in a normal time frame, and in
> the normal time frames for each mold, the clay walls are very thin. What
> normally would be a 1/4 inch wall thickness in one hour - is far less in
> three hours. Then, after emptying the molds, and allowing for setting up
> of the new shell - upon opening the molds - the clay is stuck to the
> molds and the piece is torn apart - on every single mold. I am stumped.
> The only variable I can think of is that I used sodium silicate from a
> new bottle, instead of the from the old bottle. The source of the new is
> different than the old, but the viscosity appears the same, and they are
> both clear.
>
> If anyone has any insight into this problem, I would appreciate hearing
> about it. I've got a gallery showing in three weeks and I have got to
> get this problem licked.
>
> Thanks,
>
> John
>
Julie Brooks on tue 10 jul 12
Hello,
For general information....Description of B Mix Dry (WC401D) specifical=
=3D
ly
says not to use for slip casting.=3D20
Recommended body to use for same look and much better casting success i=
=3D
s
S-2459D.=3D20
Sorry to hear you are having technical issues...you can contact
1-800-452-4862 or email Juan@lagunaclay.com (ext 213) or
Jpacini@lagunaclay.com (ext.228)
Thanks,
Julie Brooks,
Creative Director
JRodgers on tue 10 jul 12
Hi Julie,
Yes, the B-mix S2459D is the one I have been using for years. I like it
very much. I use it, and the C-5 B-mix throwing body together because
the two are sufficiently compatible that I can mix and match slipcast
and hand built parts to produce some unique ceramic work. BUT - I DO NOT
mix the throwing body scraps with the slipcasting body scraps. That is a
no-no, period. Much of my work is productions - more than a few, and I
like to have the tightness of control that slipcasting of forms gives
me. The throwing body then allows me to create unique and unusual
decorative attachments to produced a finished piece.
Thanks for your input.
John
On 7/10/2012 2:45 PM, Julie Brooks wrote:
> Recommended body to use for same look and much better casting success is
> S-2459D.
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