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glaze mixing problem

updated mon 20 jul 98

 

Bonnie Staffel on wed 15 jul 98

July 15, 1998

Dear Clayarters:

A potter friend who isn't on the Internet yet asked me to pose this
question and to try to find an answer to his problem. He mixed his
usual glaze, thicker at first and then adding water to get the right
reading on the hydrometer. The formula is based on a Kona F4 feldspar
and included 2% bentonite. All mixed fine except that the glaze settled
out very quickly and he had to stir between each dipping of his pots. He
let the glaze settle and removed some of the water and repeated this for
two or three days to try to get it to the right hydrometer reading. He
still had to stir between dippings.

When fired, the underside of his bowls looked "frothy" and/or dry with
pits and soft craters that did not flow together. The top side of the
pot fired fine. Some of his pots did not take on a proper thickness of
glaze. He bisque fires at <06. I make this glaze all the time and have
used this formula for thirty years and have never had this happen. My
only addition is 1/4% CMC which he doesn't use. His dry surface is also
very dusty. He had trouble getting his hydrometer to read correctly
because of the fast settling. He initially mixes the glaze with a paint
mixer and then seives the glaze several times. I also do all these
things. The other glaze ingredients consist of whiting, kaolin, zinc,
flint and zircopax. He is concerned that the Kona F4 is the culprit.

Anyone out there with some theories or answers?

Bonnie Staffel bstaffel@freeway.net

John Hesselberth on thu 16 jul 98

Bonnie, Sounds like the glaze, for whatever reason needs to be
floculated with some Epson salts or similar material. There is an
excellent series of 2 articles on this in recent issues of Clay Times
written by Pete Pinnell. First clear writing on this subject I've seen.
The difference between your experience and your friend's could be as
small as a difference in the water composition. It could also be that
your friend picked up the wrong bag for one of the ingredients. I'd see
if it happened twice in a row before I worried about it too much. Could
also be a new batch of one of the ingredients. At any rate, floculating
the glaze should help. Start with a couple tablespoons of a saturated
Epson Salt solution per gallon of mixed glaze and add more until the
problem comes under control. John

>----------------------------Original message----------------------------
>July 15, 1998
>
>Dear Clayarters:
>
>A potter friend who isn't on the Internet yet asked me to pose this
>question and to try to find an answer to his problem. He mixed his
>usual glaze, thicker at first and then adding water to get the right
>reading on the hydrometer. The formula is based on a Kona F4 feldspar
>and included 2% bentonite. All mixed fine except that the glaze settled
>out very quickly and he had to stir between each dipping of his pots. He
>let the glaze settle and removed some of the water and repeated this for
>two or three days to try to get it to the right hydrometer reading. He
>still had to stir between dippings.
>
>When fired, the underside of his bowls looked "frothy" and/or dry with
>pits and soft craters that did not flow together. The top side of the
>pot fired fine. Some of his pots did not take on a proper thickness of
>glaze. He bisque fires at <06. I make this glaze all the time and have
>used this formula for thirty years and have never had this happen. My
>only addition is 1/4% CMC which he doesn't use. His dry surface is also
>very dusty. He had trouble getting his hydrometer to read correctly
>because of the fast settling. He initially mixes the glaze with a paint
>mixer and then seives the glaze several times. I also do all these
>things. The other glaze ingredients consist of whiting, kaolin, zinc,
>flint and zircopax. He is concerned that the Kona F4 is the culprit.
>
>Anyone out there with some theories or answers?
>
>Bonnie Staffel bstaffel@freeway.net


John Hesselberth
Frog Pond Pottery
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com
visit my web site at http://www.frogpondpottery.com

"Why should we be in such desperate haste to succeed and in such
desperate enterprises? If a man does not keep pace with his companions,
perhaps it is because he hears a different drummer. Let him step to the
music he hears, however measured or far away." Henry David Thoreau,
Walden, 1854

Fay & Ralph Loewenthal on fri 17 jul 98

Bonnie I am sure that John meant to say defloculate,
because that friend's glaze is floculating. We usually put in
about 1 teaspoon of epson salts, dissolved in warm water
per 1 kilogram (2.254 Lbs) of dry glaze. If this does not work
then we use dissolved calcium chloride, but I have found
one glaze / frit that we use that settles out, while not in use
no matter what we do. We have never had it that we had to
stir between dipping each pot. Hope this helps Ralph in PE
SA

Richard Burkett on sat 18 jul 98

No, I really did mean to say flocculate. According to the article in
Clay Times by Pete Pinnell "A flocculated glaze settles slowly and into a
soft, open layer. A deflocculated glaze will settle into a thin,
rock-hard layer that can only be budged with dynamite...The answer to the
problem is to add something that will counteract the deflocculant and
bring the clay back into a flocculated state. That something is called a
flocculant...The most common flocculants potters use are epsom salts and
calcium chloride although..."

The terms flocculate(ant) and deflocculate(ant) are among the most
confusing in potter land. That's why I recommend Pete's articles which,
by the way, are in the March/April and May/June 1998 issues of Clay
Times. Pete recently told me he sometimes lurks on ClayArt; maybe he'd
like to comment.

At least we agree on the remedy. Epsom salts! Be careful not to add too
much though or the glaze will sometimes thicken into a gel

John.

>----------------------------Original message----------------------------
>Bonnie I am sure that John meant to say defloculate,
>because that friend's glaze is floculating. We usually put in
>about 1 teaspoon of epson salts, dissolved in warm water
>per 1 kilogram (2.254 Lbs) of dry glaze. If this does not work
>then we use dissolved calcium chloride, but I have found
>one glaze / frit that we use that settles out, while not in use
>no matter what we do. We have never had it that we had to
>stir between dipping each pot. Hope this helps Ralph in PE
>SA


John Hesselberth
Frog Pond Pottery
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com
visit my web site at http://www.frogpondpottery.com

"Why should we be in such desperate haste to succeed and in such
desperate enterprises? If a man does not keep pace with his companions,
perhaps it is because he hears a different drummer. Let him step to the
music he hears, however measured or far away." Henry David Thoreau,
Walden, 1854

Cindy on sat 18 jul 98

Bonnie,

I suggest that, along with the recipe, you supply your friend with a few
gallons of your own water. This may (or may not) solve his problem. It's
worth a try.

Cindy Strnad
Earthen Vessels
Custer, SD
USA http://blackhills-info.com/a/cindys/menu.htm

Berry Silverman on sat 18 jul 98

John Hesselberth wrote:
>
> No, I really did mean to say flocculate. According to the article in
> Clay Times by Pete Pinnell "A flocculated glaze settles slowly and
into a
> soft, open layer. A deflocculated glaze will settle into a thin,
> rock-hard layer that can only be budged with dynamite...The answer
to the
> problem is to add something that will counteract the deflocculant and
> bring the clay back into a flocculated state. That something is
called a
> flocculant...The most common flocculants potters use are epsom salts
and
> calcium chloride although..."
>
> The terms flocculate(ant) and deflocculate(ant) are among the most
> confusing in potter land. That's why I recommend Pete's articles
which,
> by the way, are in the March/April and May/June 1998 issues of Clay
> Times. Pete recently told me he sometimes lurks on ClayArt; maybe
he'd
> like to comment.
>
> At least we agree on the remedy. Epsom salts! Be careful not to add
too
> much though or the glaze will sometimes thicken into a gel
>
> John.
> > >----------------------------Original
message----------------------------
> >Bonnie I am sure that John meant to say defloculate,
> >because that friend's glaze is floculating. We usually put in
> >about 1 teaspoon of epson salts, dissolved in warm water
> >per 1 kilogram (2.254 Lbs) of dry glaze. If this does not work
> >then we use dissolved calcium chloride, but I have found
> >one glaze / frit that we use that settles out, while not in use
> >no matter what we do. We have never had it that we had to
> >stir between dipping each pot. Hope this helps Ralph in PE
> >SA
>
>
> John Hesselberth
> Frog Pond Pottery
> Pocopson, PA 19366 USA
> EMail: john@frogpondpottery.com
> visit my web site at http://www.frogpondpottery.com
>
I try to remember the difference by associating flocculant with
"flock" -- things flock together, come together to be thicker.
Deflocculant is to de-flock, or spread out, separate. It works for
me, but I still have to concentrate.
==
Berry Silverman
Berryware - Tucson, Arizona
berrysilverman@yahoo.com
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Linda Arbuckle on sun 19 jul 98

Re:
>----------------------------Original
message----------------------------
>Bonnie I am sure that John meant to say defloculate,
>because that friend's glaze is floculating. We usually put in
>about 1 teaspoon of epson salts, dissolved in warm water
>per 1 kilogram (2.254 Lbs) of dry glaze. If this does not work
>then we use dissolved calcium chloride, but I have found
>one glaze / frit that we use that settles out, while not in use
>no matter what we do. We have never had it that we had to
>stir between dipping each pot. Hope this helps Ralph in PE
>SA

I missed the original problem, but wondered if you needed a bit of clay
in the glaze so that it could be successfully flocculated. Some fritted
lowfire glazes have no clay content, so up to 2% bentonite is added to
counter the tendency of this kind of raw glaze to be extra fragile and
powdery dry (hard to handle in loading), and to provide some clay
particles to flocculate to counter settling. A reminder... if you use
bentonite, you need to mix it w/your dry ingredients and then add water,
as bentonite bloats in water. Dry bentonite added to a liquid just balls
up and is difficult to mix. Macaloid is more expensive synthetic
bentonite that you can add directly to wet glazes.

Linda

--
Linda Arbuckle
Graduate Coordinator, Assoc. Prof.
Univ of FL
School of Art and Art History
P.O. Box 115801, Gainesville, FL 32611-5801
(352) 392-0201 x 219
e-mail: arbuck@ufl.edu