[Clayart] Clayart Digest, Vol 105, Issue 13

ronroy at ca.inter.net ronroy at ca.inter.net
Sat Aug 24 16:27:01 UTC 2024 

Hi Jeremy,

I compared ball clay (bell Dark) with bentonite using the analysis  
feature of Insight and the amount of silica is about the same but the  
alumina is lower - so choosing a ball clay with the most amount of  
alumina is probably the better way.

That would be Jackson ball clay according to the analysis I have in my  
glaze course book. I don't know if it is still available.

I can check your calculation if you tell me what kind of ball clay you used.

I can also convert the first recipe using ball clay instead of kaolin  
but what spar do I use?

I think at this point you may be seeing the wisdom in purchasing some  
bentonite - it really is a useful material.

If you want me to send you my glaze course book - send a request to my  
email. It's free to anyone who wants it - it has all the analysis I  
have collected over the years and much more.

RR

Quoting Jeremy Keala Ceramics via Clayart <clayart at lists.clayartforum.com>:

> 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:
>
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>> 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 --------------
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>> >
>> >
>>
>>
>>
>> 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
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>> 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
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Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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