[Clayart] Calcining Bentonite

[Helen Stone via Clayart]

Dear Potters,
Sorry, a last question. Could I maybe calcine some bentonite, in order to
add it to my glazes? I raw glaze and was only doing soda firings, but the
last soda firing backfired and showed me a real problem with the glazes. In
this soda firing, I apparently pushed the damper in too much for too much
reduction as I was blowing in the soda mixture, as I could see the soda
mixture immediately exiting the kiln ports maybe for a foot out. The pots
in this firing all had the glazes crawled, something that appeared to have
been hidden during the other soda firings, as the natural soda glaze
obscured this problem. Now I could see it and knew that I needed to
calcine some clay materials before adding them in small additions to the
glaze recipes, to avoid disaster. I plan to calcine some native kaolin,
some bought ball clay and am thinking about the bentonite now. What do you
think?
Gratefully,
Helen in southern Ecuador.
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[Terry Lazaroff via Clayart]

Hellen;

perhaps you should do some testing prior to committing a kiln load of work. When I read your posting, I see that you are grasping at anything in order to find the result you wish. You mentioned that your previous firing went well and this one was not up to your expectations.

Perhaps you should just sit down and review what you did for the previous firing, and then see what you changed in the last firing.

Also reading from your first posting, you mentioned that you dig your own materials. Are you sure that the material in the second batch of pots is the same as the first. Sometimes the material can vary with in a few feet. I am just guessing here as I am unable to see where your material is being taken.

I admire your courage to single fire and to make your own clay. Do you have a website or a face book page where you can post photos?

best
Terry

________________________________
From: Clayart <clayart...@lists.clayartforum.com> on behalf of Helen Stone via Clayart <cla...@lists.clayartforum.com>
Sent: Saturday, May 25, 2024 3:31 PM
To: cla...@lists.clayartforum.com <cla...@lists.clayartforum.com>
Cc: Helen Stone <helenest...@gmail.com>
Subject: [Clayart] Calcining Bentonite

URL: <https://lists.clayartforum.com/pipermail/clayart/attachments/20240525/7e8f8116/attachment.htm>

[sumi via Clayart]

Helen

I think if the bentonite were to be calcined, it would lose the
beneficial property we value it for, namely the ability to suspend a glaze.

Sumi

--
Sumi von Dassow
President, Beulah Valley Arts Council

[Snail Scott via Clayart]

On May 25, 2024, at 2:31 PM, Helen Stone via Clayart <cla...@lists.clayartforum.com> wrote:
> ...Could I maybe calcine some bentonite, in order to
> add it to my glazes? ...glazes crawled…

Maybe it would be as effective to simply use less bentonite? Maybe less ball clay, too, if that doesn’t do it, and replace with more calcined kaolin. Simply using less of the most plastic materials seems like an easy experiment.

-Snail