Sue Beach on sat 30 oct 10
I have a glaze that I like very much but I'm having problems with it. I
would appreciate insight & suggestions.
I always sieve my glaze ingredients as I am making the glaze. Once the
glaze is mixed up with water, however, this one always has little white
specks in it that do not dissolve.
I have strained the wet glaze through sieves also. That works for awhile,
then the white specks come back. If the bucket of glaze sits awhile, it is
as if it grows white specks.
Wherever one of these white specks is on a pot after it is glazed, is a har=
d
white bump after firing. I have tried smoothing out the specks when they
appear on a pot & that helps if there are only a few.
I fire to ^6 oxidation. The ingredients in this glaze are: ferro frit
3195, wollastonite, nepheline syenite, epk, and silica.
My questions are: 1) Which ingredient is the one that is lumping? 2)
Any suggestions for preventing this lumping or getting the culprit to
dissolve?
Thanks for any guidance.
Sue Beach
Beach Pottery
Muncie, IN
SueBeachPottery.com
Ron Roy on sat 30 oct 10
Hi Sue,
The Neph Sy leaches sodium into the glaze slop - it may be reacting
with something in your water,
I can reformulate the glaze to get the neph sy out - or at least some
of it but I would mix the glazes with distilled water first to see if
that cures the problem - just do a small batch and leave it in a cool
place.
You may be able to melt those crystals by heating them - or prevent
them forming by keeping that glaze in a warm place.
Send me the recipe and I'll take a look - it may be fairly east to fix,
RR
Quoting Sue Beach :
> I have a glaze that I like very much but I'm having problems with it. I
> would appreciate insight & suggestions.
>
> I always sieve my glaze ingredients as I am making the glaze. Once the
> glaze is mixed up with water, however, this one always has little white
> specks in it that do not dissolve.
>
> I have strained the wet glaze through sieves also. That works for awhile=
,
> then the white specks come back. If the bucket of glaze sits awhile, it =
is
> as if it grows white specks.
>
> Wherever one of these white specks is on a pot after it is glazed, is a h=
ard
> white bump after firing. I have tried smoothing out the specks when they
> appear on a pot & that helps if there are only a few.
>
> I fire to ^6 oxidation. The ingredients in this glaze are: ferro frit
> 3195, wollastonite, nepheline syenite, epk, and silica.
>
> My questions are: 1) Which ingredient is the one that is lumping? 2)
> Any suggestions for preventing this lumping or getting the culprit to
> dissolve?
>
> Thanks for any guidance.
>
> Sue Beach
> Beach Pottery
> Muncie, IN
>
> SueBeachPottery.com
>
paul gerhold on sun 31 oct 10
Try distilled water
ivor and olive lewis on sun 31 oct 10
Dear Ron Roy and Sue,
Carbon dioxide from the atmosphere dissolves in water to form Carbonic Acid=
.
If sufficient Sodium is leaching into the water and water is evaporating
from the slop then it is possible that Sodium Carbonate is crystallising as
its concentration rises.
I have used a lot of Soda Felspar (13% Na2O) and never experienced this
phenomenon.
Regards,
Ivor Lewis,
REDHILL,
South Australia
Steve Slatin on mon 1 nov 10
I have used the following --
Whiting 56
Dolomite 5
Silica 39
This is not an 'on the button' sub, but if you
have these three materials they do a good sub
in terms of general behavior and color response.
Steve Slatin --=3D20
N48.0886450
W123.1420482
--- On Mon, 11/1/10, David Finkelnburg wrote:
> Sue,
> =3DA0 =3DA0 I suggest that you test replacing the
> wollastonite with whiting and
> silica.=3DA0 Wollastonite is prone to aging and forming
> the hard, white lumps
> you have found. =3D0A=3D0A=3D0A
David Finkelnburg on mon 1 nov 10
Sue,
I suggest that you test replacing the wollastonite with whiting and
silica. Wollastonite is prone to aging and forming the hard, white lumps
you have found. If you're willing to fuss with it you could screen the
wollastonite through a very fine sieve. None of your other ingredients
should be a problem. I'd offer a recalc but I'm in an airport and don't hav=
e
the software.
Best,
Dave Finkelnburg
http://www.mattanddavesclays.com
On Sat, 30 Oct 2010 Sue Beach wrote:
I have a glaze that I like very much but I'm having problems with it....I
would appreciate insight & suggestions.
I always sieve my glaze ingredients as I am making the glaze. Once the
glaze is mixed up with water, however, this one always has little white
specks in it that do not dissolve.
The ingredients in this glaze are: ferro frit
3195, wollastonite, nepheline syenite, epk, and silica.
Eric Hansen on mon 15 nov 10
I have gotten flecks of crap from wollastonite too -
- h -
On Mon, Nov 1, 2010 at 5:59 PM, David Finkelnburg
wrote:
> Sue,
> =3DA0 =3DA0I suggest that you test replacing the wollastonite with whitin=
g an=3D
d
> silica. =3DA0Wollastonite is prone to aging and forming the hard, white l=
um=3D
ps
> you have found. If you're willing to fuss with it you could screen the
> wollastonite through a very fine sieve. None of your other ingredients
> should be a problem. I'd offer a recalc but I'm in an airport and don't h=
=3D
ave
> the software.
> =3DA0 Best,
> =3DA0 =3DA0 =3DA0 Dave Finkelnburg
> =3DA0 =3DA0 =3DA0 http://www.mattanddavesclays.com
>
> On Sat, 30 Oct 2010 Sue Beach wrote:
> I have a glaze that I like very much but I'm having problems with it....I
> would appreciate insight & suggestions.
> I always sieve my glaze ingredients as I am making the glaze. =3DA0Once t=
he
> glaze is mixed up with water, however, this one always has little white
> specks in it that do not dissolve.
> The ingredients in this glaze are: =3DA0ferro frit
> 3195, wollastonite, nepheline syenite, epk, and silica.
>
--=3D20
Eric Alan Hansen
Stonehouse Studio Pottery
Alexandria, Virginia
americanpotter.blogspot.com
thesuddenschool.blogspot.com
hansencookbook.blogspot.com
"Simplify, simplify, simplify" - Thoreau
David Woof on sat 20 nov 10
Hi Sue=3D2C =3D20
Wolastonite contributes beneficial properties to a glaze that whiting does =
=3D
not contribute and a glaze calc program does not address.
You lose these benefits when simply asking a computor to do a unity recalc.
=3D20
Wolastonite is very hydroscopic in nature. The flecks of "crap" are still w=
=3D
ollastonite and the benefits of the wollastinite are worth the effort to si=
=3D
ft out the "undisolvable" chunks. Store wollastonite as you would plaster (=
=3D
air/moisture tight) and the problem is mitigated. Plan ahead for quanity=
=3D
=3D2C use fresh. don't give up on the wolastonite untill you know it intim=
at=3D
ely!!!
=3D20
David Woof...... Clarkdale=3D2C Az.......I and some die hard students re gi=
vi=3D
ng "little larry" (his) first soda firing tonite. my butt is draggin a bit =
=3D
but my head is clear and the fire is calling so.... hi ho hi ho.....
=3D20
_______________________________________________________________________
6a. Re: Glaze Ingredient Not Dissolving
Posted by: "Eric Hansen" eric.hambone.hansen@GMAIL.COM=3D20
Date: Mon Nov 15=3D2C 2010 8:45 am ((PST))
I have gotten flecks of crap from wollastonite too -
- h -
On Mon=3D2C Nov 1=3D2C 2010 at 5:59 PM=3D2C David Finkelnburg
wrote:
> Sue=3D2C
> I suggest that you test replacing the wollastonite with whiting and
> silica. Wollastonite is prone to aging and forming the hard=3D2C white l=
um=3D
ps
> you have found. If you're willing to fuss with it you could screen the
> wollastonite through a very fine sieve. None of your other ingredients
> should be a problem. I'd offer a recalc but I'm in an airport and don't h=
=3D
ave
> the software.
> Best=3D2C
> Dave Finkelnburg
> http://www.mattanddavesclays.com
>
> On Sat=3D2C 30 Oct 2010 Sue Beach wrote:
> I have a glaze that I like very much but I'm having problems with it....I
> would appreciate insight & suggestions.
> I always sieve my glaze ingredients as I am making the glaze. Once the
> glaze is mixed up with water=3D2C however=3D2C this one always has little=
whi=3D
te
> specks in it that do not dissolve.
> The ingredients in this glaze are: ferro frit
> 3195=3D2C wollastonite=3D2C nepheline syenite=3D2C epk=3D2C and silica.
>
=3D20
=3D20
=3D
David Finkelnburg on sun 21 nov 10
David,
I am not challenging your assertion below. I am curious. What are the
"beneficial properties" contributed by wollastonite and not by a combinatio=
n
of whiting and silica. Under what circumstances--how low is the firing
temperature? Curious minds want to know. Thanks!
Dave Finkelnburg
http://www.mattanddavesclays.com
-----------------------------
On Saturday, 20 Nov 2010, David Woof wrote:
Wolastonite contributes beneficial properties to a glaze that whiting does
not contribute and a glaze calc program does not address.
ivor and olive lewis on sun 21 nov 10
Dear David Woof,
I think you have a major typographical error in using Hydroscopic to
describe the behaviour of a substance that readily adsorbs moisture from th=
e
atmosphere, as do Caustic Soda and Burnt Lime. These materials are
Hygroscopic, Sodium Hydroxide to the degree that it is deliquescent. It
freely dissolves in the moisture it attracts.
My experience over twenty or so years using Wollastonite is that it is a
material that is stable in a glaze slop. Recent trials following suggestion=
s
from David Finkelnburg show that Wollastonite is insoluble in contact with
water.
Has anyone thought that there may be contaminated material on the market ? =
?
Ivor Lewis,
REDHILL,
South Australia
David Woof on wed 24 nov 10
Greetings David=3D2C
=3D20
If you=3D2C or anyone=3D2C is curious=3D2C as you say=3D2C Google [benefici=
al prope=3D
rties of wollastonite in glazes and clay bodies.]=3D20
=3D20
I think sincerely curious minds should do their own research=3D2C not just =
as=3D
k questions and passively wait for pre-digested answers.
=3D20
I appreciate that a component of Clayart is show and tell=3D2C but I serio=
us=3D
ly don't wish to participate in show off and tell!!!
=3D20
So as an educator I serve my students best when I guide and empower them in=
=3D
finding personal answers to meet their needs.=3D20
This includes encouraging them in getting to know the properties of and int=
=3D
eractions between each element and raw material in a glaze recipe.=3D20
=3D20
This is why I wrote what I wrote to Sue=3D2C and her answer back indicated =
th=3D
at she was thinking and questioning along the same lines.
=3D20
And yes I am thankful for the convenience of glaze calc programs and thanks=
=3D
to those others who develop the great variety of glazes from using these p=
=3D
rograms.
=3D20
However I am also thankful to my first mentor/instructor=3D2C Richard Josli=
n=3D
=3D2C who assigned the development of two new glazes from scratch my very f=
ir=3D
st semester=3D3B way before we had ever dreamed of glaze calc programs.
=3D20
No visions of sugar plums: just elementary geology=3D2C periodic table=3D2C=
the=3D
RO system=3D2C empirical formulas=3D2C line and tri-axial blends dancing t=
hru =3D
our heads. =3D20
=3D20
This said=3D3B I have strong feelings about unquestioning dependence on tec=
hn=3D
ology and the say so of glaze experts vs. the individual acquiring a workin=
=3D
g knowledge of the elements and raw materials for themselves. There is pow=
=3D
er=3D2C freedom=3D2C and much potential creativity when technology is combi=
ned =3D
with informed and thinking minds and brought to bear. =3D20
=3D20
And David I meant no challenge or offense toward you or what you posted. Yo=
=3D
ur reputation is part of your name.
=3D20
This same dependence fosters the ceramic materials fear mongering so many o=
=3D
f our newbies fall prey to. Good folks who dreamed since college of making=
=3D
pots and groovin into retirement in the safe arms of Mother Earth only to =
=3D
"discover" that their dream studio will kill them unless they don the full =
=3D
body condom I am still working to develop in my spare time.
=3D20
David Woof....some days at war with technology in Clarkdale=3D2C Az........=
Go=3D
d my cell phone looks small at 137 m...probably should take a prone positio=
=3D
n.......
=3D20
=3D20
_______________________________________________________________________
3a. Re: Glaze Ingredient Not Dissolving
Posted by: "David Finkelnburg" dfinkelnburg@GMAIL.COM=3D20
Date: Sun Nov 21=3D2C 2010 11:12 am ((PST))
David=3D2C
I am not challenging your assertion below. I am curious. What are the
"beneficial properties" contributed by wollastonite and not by a combinatio=
=3D
n
of whiting and silica. Under what circumstances--how low is the firing
temperature? Curious minds want to know. Thanks!
Dave Finkelnburg
http://www.mattanddavesclays.com
-----------------------------
On Saturday=3D2C 20 Nov 2010=3D2C David Woof wrote:
Wolastonite contributes beneficial properties to a glaze that whiting does
not contribute and a glaze calc program does not address.
=3D20
=3D20
=3D
David Woof on wed 24 nov 10
Hi Ivor=3D2C
thanks for the correction.
=3D20
There is always another fire to put out or control in relation to our colle=
=3D
ctive experience with the clays and raw materials we use. I appreciate the=
=3D
work you and others do and the science and technical information you all a=
=3D
re so willing to share.
=3D20
David Woof
=3D20
________________________________________________________________________
3b. Re: Glaze Ingredient Not Dissolving
Posted by: "ivor and olive lewis" iandol@WESTNET.COM.AU=3D20
Date: Sun Nov 21=3D2C 2010 11:17 am ((PST))
Dear David Woof=3D2C
I think you have a major typographical error in using Hydroscopic to
describe the behaviour of a substance that readily adsorbs moisture from th=
=3D
e
atmosphere=3D2C as do Caustic Soda and Burnt Lime. These materials are
Hygroscopic=3D2C Sodium Hydroxide to the degree that it is deliquescent. It
freely dissolves in the moisture it attracts.
My experience over twenty or so years using Wollastonite is that it is a
material that is stable in a glaze slop. Recent trials following suggestion=
=3D
s
from David Finkelnburg show that Wollastonite is insoluble in contact with
water.
Has anyone thought that there may be contaminated material on the market ? =
=3D
?
Ivor Lewis=3D2C
REDHILL=3D2C
South Australia
=3D20
=3D20
=3D
Stephani Stephenson on wed 24 nov 10
I'm reaching back into the dusty memoryl bin of some claybody endeavors f=
=3D
rom
a few years back. and I am doing so without access to my written records,=
=3D
so
..that's my excuse and I am sticking to it.
I was trying to come up with a clay body that had the lowest possible=3D20=
=3D
overall % shrinkage
for a particular project.=3D20
so first went with additions of grog and low shrinkage clays.
then I tried using ingredients that had lower LOI numbers. i figured ,
assuming the water content was the same,
using ingredients with lower LOI numbers would nudge me to lower overall
shrinkage.
what you had pre drying would be closer in weight and size to what you ha=
=3D
d
post firing.=3D20
I pondered whether less loss equals less shrinkage, whether that loss occ=
=3D
urs
with evaporation of water in drying or loss of material in firing. As I
read that now, i', not so sure it mattered one bit, but I thought it migh=
=3D
t
be worth a try.
I It is possible I read something about comparable LOI in wollastonite =
=3D
and
whiting on the digital fire website, though don't quote me on that.
I picked clays with low LOI's( as well as other necessary properties I so=
=3D
ught)
since whiting has a big LOI ,
I used wollastonite as the source of calcium in my formula.
i mixed up a small test batch and it performed best of all.
nice color, low shrinkage.
so I ordered a bag of wollastonite and other ingredients and mixed up a
bigger batch.
Maybe the wollastonite was old. maybe i could have sintered the wollaston=
=3D
ite
to dry it out first ,but i was unaware of the 'non dissolving' obstinence=
=3D
it
can and did exhibit.=3D20
I didn't notice it til I dry mixed it with other ingredients.
I did everything i could to dissolve that stuff , screen that stuff and
pulverize that stuff.
if fired, it likely would have shown up as melted blebs in the clay body,=
=3D
i'm not sure.
but it ruined that batch of clay.
Stephani Stephenson
David Finkelnburg on thu 25 nov 10
David,
The questions I asked you were what are the "beneficial properties"
contributed by wollastonite and not by a combination of whiting and silica.
Under what circumstances--how low is the firing temperature?
The use of wollastonite in low fire, fast fire tile bodies is well
documented in the technical literature. Most of the work was done by the
Russians. The issue of using any calcium source as a claybody flux,
however, is it creates a body with a fairly narrow firing range. That may b=
e
OK in an industrial setting but it's risky for studio artists. Besides, I
thought this topic was about a glaze ingredient.
Tony Hansen and many others argue that because wollastonite is a natura=
l
frit of calcium and silica it doesn't outgas CO2 and therefore makes a glaz=
e
with fewer bubbles than when one uses whiting and silica. My own testing of
the same transparent glaze made with molar equivalent amounts of either
wollastonite or whiting/silica is I have not observed a significant
difference in the size or number of bubbles in the fired glazes. In other
words, at mid and high fire I haven't found wollastonite to be the magic
bullet it has been claimed to be. I thought perhaps you had found differen=
t
results and would be willing to share the circumstances and what you saw.
Dave Finkelnburg
http://www.mattanddavesclays.com
David Woof on fri 26 nov 10
Hi David=3D2C
I too thought this was about a glaze ingredient=3D3B and as I explained in=
a=3D
previous post was just trying to incite a bit of Google reading on the kno=
=3D
wn beneficial properties as I observe that many students and potters alike =
=3D
are not making this information their own and are passively relying on expe=
=3D
rts and computer programs instead of knowing the basics of why a certain ra=
=3D
w material is included in a handed down glaze recipe. This may be enough =
=3D
for some folks and I make no judgment. =3D20
=3D20
However some yearn hungrily for more information=3D2C understanding=3D2C an=
d th=3D
e appreciation that deepens with this commitment to their craft. It's to t=
=3D
hem I wish to offer what I have=3D2C what has been given me and how to acqu=
ir=3D
e it. I want to sing in this choir if you will.
=3D20
I have nothing to offer now that is new or thought provoking but continue =
=3D
to think and apply and will always join the chorus when something worthwhil=
=3D
e arises. I have been putting a new clay body thru it's paces for the last=
=3D
six months and am pleased so far. Wollastonite is adding it's "beneficial =
=3D
properties" that we have all known for the last 20 or 30 years. I will pos=
=3D
t the recipe when I am 100% that I want my name to stand behind it.=3D20
=3D20
Thanks for not taking offense at my initial misunderstanding of your intent=
=3D
. You are most gracious.
=3D20
David Woof........Wiping a dribble of crow off my bib in Clarkdale AZ.
__________________________________________________________
5a. Re: Glaze Ingredient Not Dissolving
Posted by: "David Finkelnburg" dfinkelnburg@GMAIL.COM=3D20
Date: Thu Nov 25=3D2C 2010 8:57 am ((PST))
David=3D2C
The questions I asked you were what are the "beneficial properties"
contributed by wollastonite and not by a combination of whiting and silica.
Under what circumstances--how low is the firing temperature?
The use of wollastonite in low fire=3D2C fast fire tile bodies is well
documented in the technical literature. Most of the work was done by the
Russians. The issue of using any calcium source as a claybody flux=3D2C
however=3D2C is it creates a body with a fairly narrow firing range. That m=
ay=3D
be
OK in an industrial setting but it's risky for studio artists. Besides=3D2C=
I
thought this topic was about a glaze ingredient.
Tony Hansen and many others argue that because wollastonite is a natural
frit of calcium and silica it doesn't outgas CO2 and therefore makes a glaz=
=3D
e
with fewer bubbles than when one uses whiting and silica. My own testing of
the same transparent glaze made with molar equivalent amounts of either
wollastonite or whiting/silica is I have not observed a significant
difference in the size or number of bubbles in the fired glazes. In other
words=3D2C at mid and high fire I haven't found wollastonite to be the magi=
c
bullet it has been claimed to be. I thought perhaps you had found different
results and would be willing to share the circumstances and what you saw.
Dave Finkelnburg
=3D20
=3D
David Woof on fri 26 nov 10
Hi Stephanie=3D2C
Wollastonite: When ever ceramic industry uses a material it deserves our c=
=3D
onsidreation. I really started taking a closer look at it some 25 years ag=
=3D
o and I've been using=3D2C appreciating=3D2C observing and learning since. =
Tha=3D
nks to our folks who have made ceramic science their passion we do not have=
=3D
to wallow in semi light built on observation but still wondering why at th=
=3D
e molecular and elemental level. The window is open=3D2C the information i=
s =3D
there.
Ivor Lewis says=3D
that it is a
material that is stable in a glaze slop. Recent trials following suggestio=
=3D
ns
from David Finkelnburg show that Wollastonite is insoluble in contact with
water.> =3D20
I do not work as a lab scientist so can't speak to that except it makes sen=
=3D
se that this insolubility is one of the characteristics I have deducted thr=
=3D
ough trial and observation of improved green and fired strength in clay bod=
=3D
ies and glazes=3D2C because this micro crystalline acicular structure of th=
e =3D
wollastonite forms an insoluble lattice throughout the clay or glaze body a=
=3D
nd so structurally imparts the physical strength and durability it gets cre=
=3D
dit for. It is the primary characteristic that neither whiting nor silica=
=3D
exhibit when added as separate ingredients to the batch recipe. (except Si=
=3D
lica in its Kyanite....forms) (see also reduced gas formation in glazes)
=3D20
So the word Dissolving as used in the original inception of this thread is =
=3D
inaccurate in that what you and Sue indicated you wanted was for the wollas=
=3D
tonite to blend=3D2C mix=3D2C disappear=3D2C homogenize... into the batch m=
ixture=3D
and the flecks of probably hygroscopicly generated wollastonite chunks or =
=3D
other contaminates were not breaking up and so you couldn't trust the batch=
=3D
and discarded it.
=3D20
I observed a similar problem recently. So screened out some flecks and smal=
=3D
l bits and crushed these=3D2C with moderate pressure=3D2C and noted by tast=
e an=3D
d visual observation that they appeared to be wollastonite so I proceeded t=
=3D
o throw and fire some of the "contaminated" clay body. No blebs=3D2C no n=
eg=3D
ative effects on glazes. No apparent solution except longer mixing=3D2C no =
di=3D
sastrous consequences=3D2C then no problem...move on. The new shipment of w=
ol=3D
lastonite does not indicate these little chunks and flakes. I don't know o=
=3D
f other folk's contamination=3D2C but we always are shooting from the hip w=
he=3D
n it comes to new shipments of raw materials mined to industrial tolerances=
=3D
. So Test test Test!!!
=3D20
David Woof.....call and plan to visit when you pass Clarkdale.
______________________________________________________
Re: Glaze Ingredient Not Dissolving
Posted by: "Stephani Stephenson" revivalsteph@YAHOO.COM=3D20
Date: Wed Nov 24=3D2C 2010 1:22 pm ((PST))
=3D20
I picked clays with low LOI's.......................
I used wollastonite as the source of calcium in my formula.
i mixed up a small test batch and it performed best of all.
nice color=3D2C low shrinkage.
so I ordered a bag of wollastonite and other ingredients and mixed up a
bigger batch.
Maybe the wollastonite was old. maybe i could have sintered the wollastonit=
=3D
e
to dry it out first =3D2Cbut i was unaware of the 'non dissolving' obstinen=
ce=3D
it
can and did exhibit.=3D20
I didn't notice it til I dry mixed it with other ingredients.
I did everything i could to dissolve that stuff =3D2C screen that stuff and
pulverize that stuff.
if fired=3D2C it likely would have shown up as melted blebs in the clay bod=
y=3D
=3D2C
i'm not sure.
but it ruined that batch of clay.
Stephani Stephenson
=3D20
=3D20
=3D
| |
|
