[Clayart] Clayart Digest, Vol 105, Issue 13

Fri Aug 23 14:20:48 UTC 2024

Hello,

Thanks for the feedback. I've been thinking about your answers and how to
re-formulate my question so it's more precise :)

To give a bit more context to my question:
I started out looking at examples of Kuan glaze recipes, and as David said,
most are some combination of Feldspar, silica and calcium with bentonite as
a suspension agent. But then, reading through Nigel Wood's book I happened
upon a table of "Ge" glaze recipes, which appear similar to Kuan glazes in
their results. The two recipes are:

recipe 1
Potash feldspar : 63.5
China clay : 6.5
quartz : 22
whiting : 6.5
iron oxide : 0.8

Recipe 2
Potash feldspar : 28.3
China clay : 26
Quartz : 27
whiting : 14.5
dolomite : 2.5
iron oxide : 0.75

Seeing the kaolin present in these two recipes, I thought it might be
possible to not use bentonite. But as I'm not very good at using glaze
calculators for the moment, I was wondering about any suggestions of how to
go about replacing bentonite.

As an example, I tried using ball clay to modify this recipe from John
Britt's book :

original recipe
custer feldspar : 79
whiting : 9.5
silica : 9.5
bone ash : 2
bentonite : 2

modified with ball clay
custer feldspar: 63.8
ball clay : 10
silica : 13.1
whiting : 11.1
bone ash : 2

It shows up pretty similar on a glazy calculator, but I'm not very
knowledgeable about these calculations, so I was wondering if I was missing
some important detail in trying to replace bentonite with ball clay? Also,
given that original kuan glazes didn't use bentonite, I'm wondering how
this glaze settling problem was managed "back then"?

So I get that it's not generally easy to replace bentonite in a recipe, but
at the same time, I don't really understand why I can't replace it with
ball clay, like in this example that I tried. Hope my question is a bit
clearer. I just didn't want to write such a long email the first time
around!

Thanks for your suggestions, they have been very precious throughout all my
glaze testing.
Jeremy

On Fri, Aug 23, 2024 at 2:02 PM <clayart-request at lists.clayartforum.com>
wrote:

> Send Clayart mailing list submissions to
>         clayart at lists.clayartforum.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://lists.clayartforum.com/mailman/listinfo/clayart
> or, via email, send a message with subject or body 'help' to
>         clayart-request at lists.clayartforum.com
>
> You can reach the person managing the list at
>         clayart-owner at lists.clayartforum.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Clayart digest..."
>
>
> Today's Topics:
>
>    1. Re: Replacing bentonite (ronroy at ca.inter.net)
>    2. Re: Replacing bentonite (David Woof)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 22 Aug 2024 14:50:12 -0400
> From: ronroy at ca.inter.net
> To: Clayart international pottery discussion forum
>         <clayart at lists.clayartforum.com>
> Cc: Jeremy Keala Ceramics <jeremy.keala.ceramics at gmail.com>
> Subject: Re: [Clayart] Replacing bentonite
> Message-ID: <20240822145012.20785awwlqsqv2hw at webmail.ca.inter.net>
> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
>         format="flowed"
>
> Hi Jeremy,
>
> My general rule about bentonite is:
>
> If a glaze has less than 10% kaolin bentonite may be needed to keep
> that glaze in suspension long enough while glazing pots. That?s
> because kaolins are not very good suspenders especially if there is
> any deflocculation going on.
>
> First I would swap out the kaolin and replace with ball clay using
> calculation of course. If that would not work then add 2% bentonite.
>
> There are advantages to both ball clay and bentonite. They both add a
> toughness to dried glaze (anti powdering) and glazes dry slower after
> application.
>
> There are many published glazes that do have some bentonite but may
> not need it. Yours may be one of those. If you send me the recipe I
> can give you my opinion.
>
> In some cases a glaze may be hard panning because of the local water
> or perhaps a material that is leaking sodium into a glaze over time -
> like neph sy.
>
> In the first case using a pure form of water will correct the problem.
> In the second case adding some flocculant like Epsom salts will work -
> use very little Epsom - anyone who wants my technique for finding out
> how much to use just ask.
>
> Anyway - happy to give you an opinion.
>
> RR
>
>
>
> Quoting Jeremy Keala Ceramics via Clayart <clayart at lists.clayartforum.com
> >:
>
> > Hello,
> >
> > I?m starting to work on creating a Kuan crackle glaze. My starting
> recipes
> > have bentonite in them and I don?t currently don?t have bentonite in my
> > workshop and would like to keep it that way otherwise I just keep adding
> > new materials all the time to my list of raw materials.
> > Would you have any suggestions how to go about replacing bentonite in a
> > glaze ?
> > Thanks and all the best,
> > Jeremy
> >
> >
> > --
> > *Jeremy Keala Ceramics*
> > www.jeremykeala.com
> > Instagram : @jeremy_keala_ceramics
> > <https://www.instagram.com/jeremy_keala_ceramics/>
> > +33 (0)6 59 96 92 54
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL:
> > <
> https://lists.clayartforum.com/pipermail/clayart/attachments/20240816/8aef6a27/attachment.htm
> >
> >
>
>
>
> Ron Roy
> ronroy at ca.inter.net
> Web page ronroy.net
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 23 Aug 2024 00:58:21 +0000
> From: David Woof <woofpots at hotmail.com>
> To: Clayart international pottery discussion forum
>         <clayart at lists.clayartforum.com>
> Subject: Re: [Clayart] Replacing bentonite
> Message-ID:
>         <
> DM6PR15MB342084C2F5661080CEBCE4F6C68F2 at DM6PR15MB3420.namprd15.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Mary,
> Several of us now have responded to Jeremy's request for information re
> replacing Bentonite.
> I would consider it right and proper to hear back from him as to how his
> concerns are being resolved.
>
> Of course I'm not losing sleep, but the question has flitted through my
> musings that a growing number of folks may be not familiar with the
> long-time spirit of the traditional Clayart forum where unpaid experienced
> potters and studio artists give well considered information to those asking
> because of our dedication to the Craft.
>
> It is appreciated when the inquiring person responds to the conversation
> with a thank you, a request for further clarification, or of a sharing of
> their experience, which then is a return benefit for all.
>
> This goes to the spirit of Clayart that we are all here as students as
> well as teachers.
>
> In this way the learning experience of the Craft accumulates and never
> ceases as many continue to support the appreciation of Clayart value that
> keeps this valuable resource alive.
>
> Misneach,
>
> David
> Woof...............................................................................................................................................................
>
> ***************************************************************************************************
> ________________________________
> From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of Mary
> Winter via Clayart <clayart at lists.clayartforum.com>
> Sent: Tuesday, August 20, 2024 7:30 PM
> To: Clayart international pottery discussion forum <
> clayart at lists.clayartforum.com>
> Cc: Mary Winter <mary8252 at gmail.com>
> Subject: Re: [Clayart] Replacing bentonite
>
> Jeremy you can get 5 pounds of bentonite from US Pigment for $10. You might
> consider this.
>
> Mary
>
> On Tue, Aug 20, 2024 at 8:26?PM David Woof via Clayart <
> clayart at lists.clayartforum.com> wrote:
>
> > Hi Jeremy,
> > You asked for a replacement for Bentonite.  Perhaps we assumed you knew
> > the mineral qualities of the materials you have available to know you
> could
> > not just whip up a batch of what Bentonite could be replaced with.  So
> our
> > answers asked you to discern that there is no simple one material
> > substitute.
> > Macaloid and Bentonites are unique materials that cannot be substituted
> > singly or in combinations of raw materials you would likely have.  This
> > also requires understanding the intrinsic characters of each mineral and
> > the combination effects involved.
> >
> > We could have no doubt wasted your time telling you to take a high
> > plasticity synthesized Ball clay, reduce the original recipe amounts of
> > feldspar and silica and adjust the recipe ratios to accommodate these
> > additions back to the original Empirical.
> >
> > Then add enough CMC gum as a physical "mechanical" suspender, adequate
> > Hopefulness, and Sodium Silicate to deflocculate the glaze slop.    Then
> if
> > you've worked the Math correctly to arrive at a workable materials
> ratio...
> > you would still have to learn how to apply a deflocculated glaze slop
> > because the slop rheology will be way off of what most potters who use
> > flocculated glaze slops are familiar with.
> > And no doubt you would lose the Kuan Crackle glaze effect because you
> have
> > created a new Glaze. which might be an attractive glaze but not Kuan
> you'd
> > hoped for.
> > So If I gave you the adjusted amounts for this substitution most likely
> > the results wouldn't please.
> >
> > ********So back to Bentonite or Macaloid.
> >
> > Misneach,
> >
> > David
> >
> Woof.....................................................................................................................................................................
> >
> >
> ****************************************************************************************************.
> > ________________________________
> > From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of
> > Jeremy Keala Ceramics via Clayart <clayart at lists.clayartforum.com>
> > Sent: Friday, August 16, 2024 10:17 AM
> > To: clayart at lists.clayartforum.com <clayart at lists.clayartforum.com>
> > Cc: Jeremy Keala Ceramics <jeremy.keala.ceramics at gmail.com>
> > Subject: [Clayart] Replacing bentonite
> >
> > Hello,
> >
> > I?m starting to work on creating a Kuan crackle glaze. My starting
> recipes
> > have bentonite in them and I don?t currently don?t have bentonite in my
> > workshop and would like to keep it that way otherwise I just keep adding
> > new materials all the time to my list of raw materials.
> > Would you have any suggestions how to go about replacing bentonite in a
> > glaze ?
> > Thanks and all the best,
> > Jeremy
> >
> >
> > --
> > *Jeremy Keala Ceramics*
> > www.jeremykeala.com<http://www.jeremykeala.com>
> > Instagram : @jeremy_keala_ceramics
> > <https://www.instagram.com/jeremy_keala_ceramics/>
> > +33 (0)6 59 96 92 54
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL: <
> >
> https://lists.clayartforum.com/pipermail/clayart/attachments/20240816/8aef6a27/attachment.htm
> > >
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL: <
> >
> https://lists.clayartforum.com/pipermail/clayart/attachments/20240821/89319316/attachment.htm
> > >
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> https://lists.clayartforum.com/pipermail/clayart/attachments/20240820/eb768d70/attachment.htm
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> https://lists.clayartforum.com/pipermail/clayart/attachments/20240823/9a25ae48/attachment.htm
> >
>
> End of Clayart Digest, Vol 105, Issue 13
> ****************************************
>

-- 
*Jeremy Keala Ceramics*
www.jeremykeala.com
Instagram : @jeremy_keala_ceramics
<https://www.instagram.com/jeremy_keala_ceramics/>
+33 (0)6 59 96 92 54
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.clayartforum.com/pipermail/clayart/attachments/20240823/cf2d108c/attachment.htm>