Jeff Tsai on wed 23 jan 02
Hi,
I'm having a problem with two of my glazes. One of them is settling like
crazy. Here's what I did. I mixed the ingredients dry in a vented area with a
mask. I then poured in hot water and mixed that in to a good consistency. I
screened the glaze through a 30 mesh screen, followed by an 80 mesh and a 100
mesh. I thought of ball milling, but reconsidered as I figured that might
change the original glaze results and melting temperature.
Within a couple minutes of the last screening, a small 1 cm layer in a two
gallon bucket had already condensed at the bottom. it wasn't rock hard, but
stiff. Within half an hour, half the bucket had that stiffness. about ten
hours later, the bottom had a very slight almost rock hard layer and the rest
of the bottom half had become even stiffer.
If it helps, here is the glaze recipe:
61.25% Potash Feldspar
1.7% Soda Feldspar
1.24% Talc
18.29% Whiting
0.57% Bone Ash
16.90% Silica
0.28% Red Iron Ox.
1.60% Yellow Ochre
I am wondering what is the best way to go about helping to prevent settling.
I've heard of vinegar, darvan, soda ash, sodium silicate, etc. I sometimes
get confused as to whether I want to defloculate or floculate?
Here's the other glaze, but it settles a little differently. It is a
magnesium crawl glaze. WHat happens with this one is that it doesn't settle,
but gels up. Regardless of the amount of water I use the glaze seems to suck
it up and gel. I don't screen this glaze, and don't have a clue what solves
geling.
the glaze is pretty basic
55% Magnesium Carbonate
45% Nephyline Syenite
both are for cone 10 reduction too...any help would be appreciated.
-Jeffrey
vince pitelka on thu 24 jan 02
> Bentonite won't stay suspended any better than most of the components in
the
> glaze.
> I hope this makes some sense,
Denise -
No, I'm afraid it doesn't. Bentonite is well known as a suspension agent in
ceramic glazes, and it usually works very well in very small percentages
added to problem glazes that are suffering from settling problems. The
problem with this glaze has nothing to do with colloidal suspension. The
problem is just big, coarse non-plastic particles settling quickly to the
bottom of the glaze bucket and forming a rock-hard layer. As others have
pointed out, that is a frequent problem with glazes containing little or no
clay, and this recipe has none at all. In such cases the simplest solution
is usually to add bentonite or one of the refined bentonite plasticizers
like Macaloid or Veegum-T. The addition of small percentages of epsom salt
solutions may well help also, more so if a small amount of bentonite (1 to
3%) is added.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Paul Herman on thu 24 jan 02
Hi Jeff,
I use epsom salts in glazes that settle badly. Try 1/2 of one percent.
You'll be amazed.
Paul in Doyle, where it's 10 degrees out.
----------
>From: Jeff Tsai
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: settling glazes.
>Date: Wed, Jan 23, 2002, 8:53 PM
>
Jeff wrote:
> I am wondering what is the best way to go about helping to prevent settling.
> I've heard of vinegar, darvan, soda ash, sodium silicate, etc. I sometimes
> get confused as to whether I want to defloculate or floculate?
Ron Roy on thu 24 jan 02
Hi Jeffrey,
Yes - no clay is the problem - I have reformulated with ball clay and
bentonite - essentially the same glaze - the original would craze on just
about any common clay body - I have lowered the expansion somewhat but I
think it's still gonna craze.
If the settling is still a problem add some Ephesian salts (liquid form) as
per others instructions - add some to a pail full of glaze - lets say a tea
spoon - stir - let sit for half an hour - if the glaze is properly
flocculated it will stay suspended well even for weeks - you will still
have to stir it before and during use but it should be easy to keep
suspended. The combination of ball clay and bentonite responds well to
flocculation with Ephesian salts.
Potash spar - 53.5 (I used g200 - Custer will work as well)
Soda spar - 2.0 (I used f4 - no need to use this - just add 2 to the pot
spar total)
Talc - 2.0
Whiting - 18.5
OM #4 - 4.0
Silica - 19.0
Bentonite - 2.0
Total - 102.0.
I assume this is a cone 10 glaze - you should always note that when posting
recipes - also oxidation or reduction - and if it crazes etc. You should
always include the total with any recipe - yours was 99.95 - I winder if I
got all of it?
Adding in the iron and ochre makes this a celadon glaze - is that right?
The other glaze - it's a stretch calling it a glaze - way short of alumina
and silica - I can't imagine how to cope with the gelling - maybe try a
little soda ash on a small amount - if it's flocced that may help but I am
just guessing so don't experiment with a lot of glaze.
RR
>I'm having a problem with two of my glazes. One of them is settling like
>crazy. Here's what I did. I mixed the ingredients dry in a vented area with a
>mask. I then poured in hot water and mixed that in to a good consistency. I
>screened the glaze through a 30 mesh screen, followed by an 80 mesh and a 100
>mesh. I thought of ball milling, but reconsidered as I figured that might
>change the original glaze results and melting temperature.
>
>Within a couple minutes of the last screening, a small 1 cm layer in a two
>gallon bucket had already condensed at the bottom. it wasn't rock hard, but
>stiff. Within half an hour, half the bucket had that stiffness. about ten
>hours later, the bottom had a very slight almost rock hard layer and the rest
>of the bottom half had become even stiffer.
>
>If it helps, here is the glaze recipe:
>61.25% Potash Feldspar
>1.7% Soda Feldspar
>1.24% Talc
>18.29% Whiting
>0.57% Bone Ash
>16.90% Silica
>
>0.28% Red Iron Ox.
>1.60% Yellow Ochre
>
>I am wondering what is the best way to go about helping to prevent settling.
>I've heard of vinegar, darvan, soda ash, sodium silicate, etc. I sometimes
>get confused as to whether I want to defloculate or floculate?
>
>Here's the other glaze, but it settles a little differently. It is a
>magnesium crawl glaze. WHat happens with this one is that it doesn't settle,
>but gels up. Regardless of the amount of water I use the glaze seems to suck
>it up and gel. I don't screen this glaze, and don't have a clue what solves
>geling.
>
>the glaze is pretty basic
>
>55% Magnesium Carbonate
>45% Nephyline Syenite
>
>both are for cone 10 reduction too...any help would be appreciated.
>
>-Jeffrey
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Marsh Pottery on thu 24 jan 02
You can add a couple of handfuls (very scientific) of Epsom salts
(magnesium carb) to help keep it from settling so fast. (but it can develop
an odor)
2-3% Bentonite can still be added, tho it is much easier if you add it to
the dry mix. Weigh it out & add a little water, adding more as it mixes
till it's about the consistency of thick soup, then screen it into your
ready-to-use glaze & mix thoroughly, or re-screen.
Marsha
----- Original Message -----
From: "Jeff Tsai"
Subject: settling glazes.
I'm having a problem with two of my glazes. One of them is settling like
crazy. Here's what I did. I mixed the ingredients dry in a vented area with
a
mask. I then poured in hot water and mixed that in to a good consistency. I
screened the glaze through a 30 mesh screen, followed by an 80 mesh and a
100
mesh. I thought of ball milling, but reconsidered as I figured that might
change the original glaze results and melting temperature.
Within a couple minutes of the last screening, a small 1 cm layer in a two
gallon bucket had already condensed at the bottom. it wasn't rock hard, but
stiff. Within half an hour, half the bucket had that stiffness. about ten
hours later, the bottom had a very slight almost rock hard layer and the
rest
of the bottom half had become even stiffer.
Ceramic Design Group on thu 24 jan 02
on 1/23/02 9:53 PM, Jeff Tsai at DemJeffHQ@AOL.COM wrote:
>
> Within a couple minutes of the last screening, a small 1 cm layer in a two
> gallon bucket had already condensed at the bottom. it wasn't rock hard, but
> stiff. Within half an hour, half the bucket had that stiffness. about ten
> hours later, the bottom had a very slight almost rock hard layer and the rest
> of the bottom half had become even stiffer.
>
> If it helps, here is the glaze recipe:
> 61.25% Potash Feldspar
> 1.7% Soda Feldspar
> 1.24% Talc
> 18.29% Whiting
> 0.57% Bone Ash
> 16.90% Silica
>
> 0.28% Red Iron Ox.
> 1.60% Yellow Ochre
>
There is no clay in this glaze and the clay content in any glaze, (of course
when properly formulated to account for its 1:2 Alumina to SIlica Ratio)
will suspend your glaze into a well suspended glaze "slop".
OF course there are host of other additives that you can add to the
existing glaze without reformulating it, but I would suggest that this glaze
be reformulated to include some clay, which would be easy to do using
Insight or Hypergalze, or Matrix.
You might want to got to digitalfire.com for a host of information that you
might find useful.
Jonathan
--
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
infor@ceramicdesigngroup.net www.ceramicdesigngroup.net
(use PO BOX for all USPS correspondence)
970 879-9139
Plant Location
1280 13th Street
Steamboat Springs CO 80487
(use PLANT LOCATION for all UPS, Common Carrier, and Courier deliveries)
Martin Howard on thu 24 jan 02
Add some cat litter.
Works wonders.
None of my glazes have settling problems.
Martin Howard
Webbs Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
Updated 20th January 2002
Craig Martell on thu 24 jan 02
Hi:
There isn't any clay in either of these recipes so it's no wonder they
don't stay in suspension. As mentioned in another post you can add
bentonite to aid suspension plus some epsom salts. Don't do the "handful"
approach though. Weigh it out and and start with 1%. That usually does
it. I have some glazes with no clay too and I use vee gum T or macaloid to
suspend them. Usually about 2 to 3% and about a percent of MgSO4(epsom
salt). Blunge the vee gum or macaloid in warm water and add the rest of
the ingredients, mix, and screen. It's isn't necessary or helpful to mix
the other glaze ingredients in hot water.
regards, Craig Martell in Oregon
Denise Philipbar on thu 24 jan 02
Hi Jeff,
Boil a cup of water (a see through cup works best for this) and disolve
epson salts into the cup. Keep adding until no more epson salts work. Than
add this mixture a few drops at a time while stirring your glaze. Keep
whats left of the mixture around for later use. It really doesn't take much
of this and mixes better with the glaze than dry epson salts. If you add
dry, you could add too much and drastically change the chemical composition
of your glaze.
Hope this helps...Denise
-----Original Message-----
From: Jeff Tsai [mailto:DemJeffHQ@aol.com]
Sent: Wednesday, January 23, 2002 9:53 PM
To: CLAYART@lsv.ceramics.org
Subject: settling glazes.
Hi,
I'm having a problem with two of my glazes. One of them is settling like
crazy. Here's what I did. I mixed the ingredients dry in a vented area with
a
mask. I then poured in hot water and mixed that in to a good consistency. I
screened the glaze through a 30 mesh screen, followed by an 80 mesh and a
100
mesh. I thought of ball milling, but reconsidered as I figured that might
change the original glaze results and melting temperature.
Within a couple minutes of the last screening, a small 1 cm layer in a two
gallon bucket had already condensed at the bottom. it wasn't rock hard, but
stiff. Within half an hour, half the bucket had that stiffness. about ten
hours later, the bottom had a very slight almost rock hard layer and the
rest
of the bottom half had become even stiffer.
If it helps, here is the glaze recipe:
61.25% Potash Feldspar
1.7% Soda Feldspar
1.24% Talc
18.29% Whiting
0.57% Bone Ash
16.90% Silica
0.28% Red Iron Ox.
1.60% Yellow Ochre
I am wondering what is the best way to go about helping to prevent settling.
I've heard of vinegar, darvan, soda ash, sodium silicate, etc. I sometimes
get confused as to whether I want to defloculate or floculate?
Here's the other glaze, but it settles a little differently. It is a
magnesium crawl glaze. WHat happens with this one is that it doesn't settle,
but gels up. Regardless of the amount of water I use the glaze seems to suck
it up and gel. I don't screen this glaze, and don't have a clue what solves
geling.
the glaze is pretty basic
55% Magnesium Carbonate
45% Nephyline Syenite
both are for cone 10 reduction too...any help would be appreciated.
-Jeffrey
____________________________________________________________________________
__
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william schran on thu 24 jan 02
Jeffery -The glaze settles because it has no components to keep it
in suspension. You need to add clay for that. Adding bentonite in
small percentages would help.
Bill
Denise Philipbar on thu 24 jan 02
I'm not sure I agree with this. A suspension is a colloid (colloidal
chemistry). To keep something in suspension, it requires that the charge on
the particles be repulsive(like the ends on magnets). There are several
ways to do this. You could mix it long enough to create such a charge (like
static electricity after rubbing your feet on carpet), or you can add
chemicals to do that. Adding bentonite will change the composition only
slightly and you will still get settling, but the bentonite is a desicate so
it will absorbe alot of water. The Epsom salts actually changes the charge
on the particles. They will eventually flip their charge back, but that
takes a few days.
Bentonite won't stay suspended any better than most of the components in the
glaze.
I hope this makes some sense,
Denise
-----Original Message-----
From: william schran [mailto:wschran@EROLS.COM]
Sent: Thursday, January 24, 2002 3:00 PM
To: CLAYART@lsv.ceramics.org
Subject: Re: settling glazes.
Jeffery -The glaze settles because it has no components to keep it
in suspension. You need to add clay for that. Adding bentonite in
small percentages would help.
Bill
____________________________________________________________________________
__
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You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
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Paul Lewing on thu 24 jan 02
Jeff, other people have given you good advice on how to help your settling
problems, but I wondered if you realized what odd glaze recipes these both
are?
on 1/23/02 8:53 PM, Jeff Tsai at DemJeffHQ@AOL.COM wrote:
> If it helps, here is the glaze recipe:
> 61.25% Potash Feldspar
> 1.7% Soda Feldspar
> 1.24% Talc
> 18.29% Whiting
> 0.57% Bone Ash
> 16.90% Silica
>
> 0.28% Red Iron Ox.
> 1.60% Yellow Ochre
Not only does this glaze have no clay, which is what it really needs to keep
it suspended, but you could leave out the soda spar, the bone ash, and maybe
the red iron, and you wouldn't notice any difference at all. Or you could
add the two feldspars together, add the bone ash amount to the whiting
amount, and add a bit more yellow ochre, and you wouldn't notice any
difference. In fact, I'd bet you wouldn't notice much difference if you
left out the talc, too!
The other thing about this glaze that's odd is that, despite the fact that
there's no clay, there really is plenty of alumina, .37 by Insight's
calculation. And that's using the theoretical analysis for soda and potash
spars, which each have an even 1 mole of Al2O3. In fact, all the real
feldspars out there have slightly more than 1, so in reality, there's more
Al2O3 than that even.
It would be nice if you could reformulate this thing and free up some Al2O3
from somewhere to replace with clay, so you could keep the molecular formula
the same, but it's all coming from the spars. There are low-alumina frits
out there that would replace the flux action, but all of them that I know
about would introduce some boron, which might change the look of this thing.
But I'd bet you could add some kaolin to it, maybe as well as some
bentonite, without changing it too much.
> Here's the other glaze, but it settles a little differently. It is a
> magnesium crawl glaze. WHat happens with this one is that it doesn't settle,
> but gels up. Regardless of the amount of water I use the glaze seems to suck
> it up and gel. I don't screen this glaze, and don't have a clue what solves
> geling.
>
> the glaze is pretty basic
>
> 55% Magnesium Carbonate
> 45% Nephyline Syenite
No kidding that's basic! I'm sure you realize what whacked-out amounts of
MgO this one has. But one thing that's really odd about this one is that,
while it has a very high amount of SiO2 in a RO unity view, it's actually
very low on SiO2 when you look at a percentage by weight analysis. I think
that's because there are just so few oxides in this thing at all, meaning
that it's a very simple glaze chemically.
I think it's the mag carb that's causing the gel problem. If you weren't
already using the lowest-silica flux among the feldspar-type fluxes, I'd say
you should use neph sy instead and use the freed-up SiO2 to replace mag carb
with talc.
But the neph sy may also be contributing to the problem. If you replaced it
with a feldspar, it might help. It might also make the glaze a bit shinier,
since you'd have more SiO2.
Something else you might try is dissolving about 0.3% soda ash in the water
before you mix this glaze. That helps gerstley borate glazes not gel quite
so much. I'm not sure if the mechanism's the same here, but it's worth a
try.
Cindy Gatto on thu 24 jan 02
Hi Jeffery:
We had the exact same problems with our low fire glazes at first
and tried everything to no avail. Then we tried a product called Flocs from
Axner and that was the only thing that worked.
Good luck
Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn NY 11206
718-218-9424
Mudpitnyc@aol.com
www.mudpitnyc.com
Ron Roy on mon 28 jan 02
Epsom salts - Gavin says I have been reading to much bible - I say the word
Ephesian is the first word my spell checker gives when I misspell Epson.
If everyone would just stop being so nice about the book I would be able to
settle down and concentrate.
Thank you everyone - I am truly elated at the openness and willing to try
of this group of people - and humbled is a most wonderful way.
RR
>If the settling is still a problem add some Ephesian salts (liquid form) as
>per others instructions - add some to a pail full of glaze - lets say a tea
>spoon - stir - let sit for half an hour - if the glaze is properly
>flocculated it will stay suspended well even for weeks - you will still
>have to stir it before and during use but it should be easy to keep
>suspended. The combination of ball clay and bentonite responds well to
>flocculation with Ephesian salts.
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Denise Philipbar on mon 28 jan 02
Vince-
I have a couple of questions about your answer, one based on my ignorance of
some of the terms (my background is more on the physics/chemistry side of
things). What do you mean by (non)plastic particles? If the particles are
too coarse, would it help to use a ball mill or mortar and pestle to grind
them finer?
Looking back through the recipes I have, I realize that I've never
formulated a glaze without clay, so didn't even think about this when
replying. But it's peaked my curiosity. I understand why the addition of
clay would help a glaze adhere to the piece, but what would the lack of clay
do? I think someone answered that a lot of crazing might happen. I'm
curious as to what the effect of temperature might be. Are there many glaze
recipes without clay?
Thanks for your enlightening reply to my last post,
Denise
-----Original Message-----
From: vince pitelka [mailto:vpitelka@dtccom.net]
Sent: Thursday, January 24, 2002 10:01 PM
To: CLAYART@lsv.ceramics.org
Subject: Re: settling glazes.
> Bentonite won't stay suspended any better than most of the components in
the
> glaze.
> I hope this makes some sense,
Denise -
No, I'm afraid it doesn't. Bentonite is well known as a suspension agent in
ceramic glazes, and it usually works very well in very small percentages
added to problem glazes that are suffering from settling problems. The
problem with this glaze has nothing to do with colloidal suspension. The
problem is just big, coarse non-plastic particles settling quickly to the
bottom of the glaze bucket and forming a rock-hard layer. As others have
pointed out, that is a frequent problem with glazes containing little or no
clay, and this recipe has none at all. In such cases the simplest solution
is usually to add bentonite or one of the refined bentonite plasticizers
like Macaloid or Veegum-T. The addition of small percentages of epsom salt
solutions may well help also, more so if a small amount of bentonite (1 to
3%) is added.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
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Craig Martell on mon 28 jan 02
Denise wanted to know:
>If the particles are too coarse, would it help to use a ball mill or
>mortar and pestle to grind
>them finer?
Hello Denise:
I'm sure that Vince will give you a definitive answer but I just love to
butt in when I can. Actually, ball milling does help suspension. It will
homogenize the particle size of ALL the glaze constituents somewhat and
this really aids suspension. I have a celadon with no clay added and I
mill it for an hour to disperse the iron. I also add some vee gum T and a
percent of epsom salts and I've compared the milled and unmilled versions
of this glaze. The milled glaze suspends better.
>I understand why the addition of clay would help a glaze adhere to the
>piece, but what would the lack of clay do? I think someone answered that
>a lot of crazing might happen.
If you eliminate clay from a glaze the other components motate toward the
bottom of your container at a higher rate of speed and are hard to dislodge
from this area. Clay does aid in suspension. What clay contributes to the
molecular formula of a glaze is basically alumina and silica. You can get
alumina and silica from feldspars too and nepheline syenite. You could
also use alumina oxide and quartz to supply alumina and silica. If you can
satisfy your alumina and silica requirements with some clay you will have
the same molecular formula and a glaze slop that gives fewer problems in
the area of suspension.
Lack of clay is not the prime culprit with regard to crazing. The
expansion of the glaze and clay and how they relate to each other are the
main factors here. If you have a glaze that fits a claybody and you remove
the clay without replacing the lost alumina and silica with other
minerals, the glaze will most likely craze.
If you want a real eye opener about suspension, weigh the same volumes of
any clay, feldspar or nepheline syenite, and silica. I won't tell you what
you'll find. I don't wanna spoil the surprise.
regards, Craig Martell in Oregon
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