[Clayart] Fw: Blue haze on kiln shelves mystery

Edouard Bastarache edouardb at colba.net
Thu Nov 10 21:16:12 UTC 2022

1 tablespoon of dry Epsom diluted in warm water per gallon of liquid glaze.
Once added to the liquid glaze, dont sieve the glaze. Its too late then.
Moving the glaze will make it make too much bubbles.
If that ever happens wash the glaze 3-5 times as you do to prepare wood ash
to remove solubles that are causing the bubbles.

-----Message d'origine-----
De : Clayart [mailto:clayart-bounces at lists.clayartworld.com] De la part de
ronroy at ca.inter.net
Envoyé : 10 novembre 2022 11:10
À : Clayart international pottery discussion forum; Dragonbelly Ceramics
Objet : Re: [Clayart] Fw: Blue haze on kiln shelves mystery

Hi Lisa,

The is a small amount of Neph Sy in the high calcium semi mattes in our
book. It is well know that Neph Sy releases sodium into water and can result
in hard panning of glazes and defloccullated clay with certain water.. The
effect can be reversed using a small amount of Epsom salts. Anyone that
needs to know how much to add should contact me. It is important to just the
right amount because adding too much reverses the effect again.

When I lived in Toronto I never had a problem with my glazes settling.  
When we moved to the country and had a soft water system installed all my
glazes started hard panning. I now use de ionized water - distilled would
work as well. I'm not sure rain water would work - they say it may be
contaminated now.

I don't use Clazy but John Post does and I'm sure he will comment. I can't
imagine a glaze calculation program not generating a unity formula.

You did not say if you have a vent running?


Quoting Dragonbelly Ceramics <lisa at dragonbellyceramics.com>:

> I've actually run a bunch of color tests with the High Calcium Semi 
> Matt glazes from Ron's Mastering Cone 6 Glazes, but we were having 
> trouble (If I remember correctly - it was quite some time ago) with 
> keeping the glazes from hard panning. We went with the base from our 
> studio white glaze because it's the most well behaved glaze we have on all
our clay bodies.
> (Yes - there are 4 that we stock. Not my decision. I would have gone 
> with a max of 2) It's never problematic in the bucket. Always easy to 
> stir up into suspension. Tolerates being applied thick or thin. All 
> attributes important to a community studio that also runs kids classes.
> Recipe repeated here, for reference:
> White Base:
> minispar 200    46.1
> Silica                 19.7
> Gillespie Borate 13.5
> Whiting               8.2
> Dolomite             5.9
> Zinc Oxide           3.9
> Bentonite             2
> Problematic color test:
> WB-10:
> +cobalt carb 2
> +copper carb 2
> +rutile            1.5
> I don't have an insight-live account, but do use glazy. Glazy doesn't 
> calculate the limit formulas, but only the Stull charts. Do you 
> recommend using insight? Does it give substantially different information
than glazy?
> Best regards,
> LJ Cohen
> On Wed, Nov 9, 2022 at 6:49 PM David Woof <woofpots at hotmail.com> wrote:
>> Hi Ron, Lisa,
>> Yes I agree with what you said regarding the MgO.
>> Because you had stated that you had run Lisa's glaze thru the Insight 
>> program, I was counting on you to assist Lisa in re-formulation of a 
>> glaze adjusted from the Gillespie to a Boron Frit such as 3134 or 
>> 3124 or possibly 3195 etc. depending on the other glaze material 
>> constituents because you had access to her original recipe, and I no
longer do.
>> One could also scrap the whole existing glaze and start over building 
>> a new glaze around a Boron Frit.
>> (Exciting and learning prospect...!!!...???)
>> Of course, it all depends on what you, Lisa, wish to do.
>> And that you two can work it out provided both parties are willing.
>> P.S. Ron,
>> other than that I prefer a deflocculation method for glaze slop 
>> suspension in most glazing applications, and you favor Flocculation 
>> for most of same....I believe we see eye to eye on most other Ceramic
>> Especially that for many years we have beat the same drum regarding 
>> the science and ethics of creating stable glazes for vessels of 
>> Domestic Utility.
>> Live long and be well my friend....... Love, David
>> Misneach,
>> David
>> *********************************************************************
>> ******
>> ________________________________
>> From: ronroy at ca.inter.net <ronroy at ca.inter.net>
>> Sent: Tuesday, November 8, 2022 10:46 AM
>> To: Clayart international pottery discussion forum < 
>> clayart at lists.clayartworld.com>; David Woof <woofpots at hotmail.com>
>> Subject: Re: [Clayart] Blue haze on kiln shelves mystery
>> Hi David,
>> I don't think that will work. The expansion goes up because the MgO 
>> goes down a lot and - the Gillespie borate helps float the glaze in 
>> the bucket.
>> MgO is magnesium oxide and it has a low expansion rate so it's a good 
>> anti craze.
>> The Gillespie borate, which is a good replacement for Gerstley borate 
>> is hydroscopic and helps keep glazes in suspension.
>> The alumina stays the same in each case so adding clay to help the 
>> suspension issue would change the glaze.
>> RR
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> --
>         http://www.dragonbellyceramics.com
> *           where imagination meets function*
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Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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