James L Bowen on thu 17 feb 00
-------------------
After having too many glazes settle to the bottom of the bucket and not =
knowing
how to incorperate CMC powder to the mix I decided to add 2=25 bentonite to =
the
dry ingredients of each glaze batch, however, I am sure some probably =
wouldn't
have needed it. So, how do I tell based on the ingedients contained in the
glaze when I won't need a glaze suspender.
Cindy Strnad on thu 17 feb 00
James,
Glazes with ten percent or more clay ingredients (Ball Clay, EPK, Redart,
etc.) don't usually need bentonite.
Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
Jim Cullen on fri 18 feb 00
I had the opportunity to talk one-on-one with Steven Hill after one of his
workshop/demonstrations and we were discussing spraying glazes in general.
the comment that stuck with me more than any other was "If you are spraying,
put bentonite in your glazes." It didn't seem to matter what the recipe was,
or the material content...it seemed to be a matter of how the glaze was being
applied.
Does this make sense to you all?
I started putting bentonite into my glazes the next day. Who am I to argue
with Steven Hill? My reasoning is that, with spraying you want to be sure
nothing settles out, if you're sucking off the top and if you're using a
gravity feed, you don't want a concentration at the bottom.
Makes sense to me.
I did adopt mel's method of mixing a bottle (plastic) of bentonite gel and I
whisk that into my glaze water before adding the dry materials. Works great
and until someone comes up with a better reason for me not to, that's the way
I'm going to continue mixing my glazes for spraying.
KEEP CENTERED
Cullen
Naperville, Illinois
martin howard on fri 18 feb 00
If only we always knew the composition of bought glazes. Then we could use a
glaze program on the computer and just add sufficient bentonite to keep the
Al2O3 content within the limits for that kind of glaze.
Martin Howard
Webb's Cottage Pottery
Woolpits Road
Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
www.webbscottage.co.uk Should be ready for 2000 :-) or 2001
Stephen Grimmer on sat 19 feb 00
Jim,
I would have to come down on the side of weighing dry bentonite that you
put into glazes as you do the other ingredients. Typically, one would add 2%
bentonite to a glaze containing less than 10% clay. If you are applying
glaze to greenware, you could double that. If your glaze has 20% EPK or
more, you don't need any bentonite to keep it suspended. The problem with
just adding it as a gel is that you don't know how much you are getting. 2%?
10%? Some glazes may not be sensitive to variations, but a glaze with lots
of clay, magnesium carbonate, gerstley borate, or iron oxide might be
fussier to such cavalier treatment. Your mileage may vary, however.
steve
--
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Jim Cullen
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Bentonite in glaze
>Date: Fri, Feb 18, 2000, 9:57 AM
>
Snip!
> I did adopt mel's method of mixing a bottle (plastic) of bentonite gel and I
> whisk that into my glaze water before adding the dry materials. Works great
> and until someone comes up with a better reason for me not to, that's the way
> I'm going to continue mixing my glazes for spraying.
>
> KEEP CENTERED
> Cullen
> Naperville, Illinois
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