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calcination of glaze vs specific ingredient

updated wed 1 jun 11

 

Thomas G. Sawyer, M.D., J.D. on sun 22 may 11


Some time ago I obtained a glaze from clayart called ebony; it consists of
50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself but
works really good under other glazes. A fair number of glaze one uses as th=
e
top glaze, however, dry, crack and fall off. I was looking to calcinate the
barnard's by itself but wonder if I could just calcinate the mixture instea=
d
since I have a bunch of this already made up. The question goes a little
deeper though and I would like to ask whether calcinating a glaze batch
would cause any problems versus calcinating just a specific ingredient.
Thanks to all who offer their opinions and experience.



Tom Sawyer

Orlando, Florida





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John Post on sun 22 may 11


I have a glaze that I use that has significant amounts of Barnard in
it and a little bit of flux. It sinks to the bottom of the bucket like
a rock.

I don't think calcining the Barnard will hurt, and it could help.

But what I did was I ran a line blend of two glazes.

One that was my Barnard glaze and one that was 100% Ball clay.

I use a 60 cc veterinary syringe (item 12970 from http://www.valleyvet.com/
) to mix the line blend of the two glazes. Both glazes are made to
same volume meaning that if you pour them into a graduated cylinder
they both measure the same.

I found that after I had a glaze that had some ball clay in it, I
could add a little epsom to the mix and I ended up with a much better
behaved glaze.

John Post
Sterling Heights, Michigan

http://www.johnpost.us

Follow me on Twitter
https://twitter.com/UCSArtTeacher

Snail Scott on sun 22 may 11


On May 22, 2011, at 9:46 AM, Thomas G. Sawyer, M.D., J.D. wrote:
> ...a fairly nice glaze by itself but
> works really good under other glazes. A fair number of glaze one uses =3D
as the
> top glaze, however, dry, crack and fall off...


Often, when the second coating flakes off, it's
because the underlayer is dusty and/or fragile. =3D20
You can add gum or bentonite to help harden the=3D20
base coat, or bisque the base coat in place so=3D20
that it won't be powdery when the top coat goes=3D20
on. (You can re-bisque to a low temp, or apply=3D20
the bottom glaze while the clay is still green.)

-Snail=3D

Paul Lewing on sun 22 may 11


On May 22, 2011, at 7:46 AM, Thomas G. Sawyer, M.D., J.D. wrote:

wonder if I could just calcinate the mixture instead
since I have a bunch of this already made up.

You could do that and it wouldn't make any difference. The frit is
essentially already calcined. Incidentally, the word is calcine, not
calcinate, but then I'm a grammar Nazi. Sorry.

Paul Lewing
www.paullewingtile.com
www.paullewingart.com

Paul Herman on sun 22 may 11


Hi Tom,

I would calcine the Barnard separately, because the frit 3134 has a
very low melting point. I would think if you calcine the combination,
it would fuse enough that you would have to grind the resulting
material in the ball mill or somehow, making a lot of work for
yourself. I think if you just calcine the Barnard alone to a fairly
low bisque temperature, like 010 or 08, you would get a resulting
material that could be used in the glaze with no further grinding.

You didn't include the firing temp of your glaze, is it high fire?

best wishes,

Paul Herman

Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/




On May 22, 2011, at 7:46 AM, Thomas G. Sawyer, M.D., J.D. wrote:

> Some time ago I obtained a glaze from clayart called ebony; it
> consists of
> 50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by
> itself but
> works really good under other glazes. A fair number of glaze one
> uses as the
> top glaze, however, dry, crack and fall off. I was looking to
> calcinate the
> barnard's by itself but wonder if I could just calcinate the mixture
> instead
> since I have a bunch of this already made up. The question goes a
> little
> deeper though and I would like to ask whether calcinating a glaze
> batch
> would cause any problems versus calcinating just a specific
> ingredient.
> Thanks to all who offer their opinions and experience.
>
>
>
> Tom Sawyer
>
> Orlando, Florida

William & Susan Schran User on sun 22 may 11


On 5/22/11 10:46 AM, "Thomas G. Sawyer, M.D., J.D."
wrote:

> Some time ago I obtained a glaze from clayart called ebony; it consists o=
f
> 50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself bu=
t
> works really good under other glazes. A fair number of glaze one uses as =
the
> top glaze, however, dry, crack and fall off. I was looking to calcinate t=
he
> barnard's by itself but wonder if I could just calcinate the mixture inst=
ead
> since I have a bunch of this already made up. The question goes a little
> deeper though and I would like to ask whether calcinating a glaze batch
> would cause any problems versus calcinating just a specific ingredient.
> Thanks to all who offer their opinions and experience.

More than likely calcining the total glaze will sinter/begin to melt the
frit, then you'll need to grind the whole thing back down to a powder.
Don't think calcining is the answer.
How long do you wait to apply the top glaze?
If the first glaze dries too much, the 2nd will often do what you write
about, crack and peel. Try applying 2nd glaze as soon as the first is dry t=
o
the touch and see if that works. If not, you might try adding a gum binder
to the 2nd glaze for better adhesion.
If the 2nd glaze contains materials that shrink a great deal on drying,
clays or zinc, you could calcine them.
But then again, it might be that you just need to calcine the barnard slip.

Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com

Michael Wendt on sun 22 may 11


Tom,
I use a local slip clay that makes a great glaze and found
that
the best way to solve this is to dip in the slip glaze, wash
up
then bisque the entire pot again.

The result is the next layer "sees" the slip glaze as
ordinary
bisque ware since it is totally bonded to the body and
solves
the flaking issue without the need to resort to complex
calcination
schemes.

Furthermore, you can repeat the bisque and layer process as
many times as needed on a pot but be sure to put a saucer
under the pot if you haven't tested how badly multiple
layers will run.
Regards,
Michael Wendt
www.wendtpottery.com
Tom Sawyer wrote:
Some time ago I obtained a glaze from clayart called ebony;
it consists of
50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze
by itself but
works really good under other glazes. A fair number of glaze
one uses as the
top glaze, however, dry, crack and fall off. I was looking
to calcinate the
barnard's by itself but wonder if I could just calcinate the
mixture instead
since I have a bunch of this already made up. The question
goes a little
deeper though and I would like to ask whether calcinating a
glaze batch
would cause any problems versus calcinating just a specific
ingredient.
Thanks to all who offer their opinions and experience.



Tom Sawyer

Orlando, Florida

David Hendley on sun 22 may 11


Hey Dr. Tom, I have never calcined a mixed glaze, but any and all frits
are, by definition, "calcined". They are actually fired to a high
temperature,
so the ingredients melt, and then ground back down into powder.
Soo..I can't see how it could change anything to refire a frit to a
relatively low temperature. All the organics, chemical water, etc.
are already long gone.

Here's another idea: I sometimes layer a lichen glaze over a black
Redart glaze (Albany slip glaze recalculated to use Redart). Same
problem - the top glaze cracks and falls off. My solution is to treat
the black glaze like a slip (it is a high-clay glaze like yours), applying
it to still-damp clay. After this goes through the bisque fire, the top
glaze adheres better without cracking off nearly as bad.
David Hendley
david@farmpots.com
http://www.farmpots.com
http://www.thewahooligans.com


----- Original Message -----
> Some time ago I obtained a glaze from clayart called ebony; it consists o=
f
> 50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself bu=
t
> works really good under other glazes. A fair number of glaze one uses as
> the
> top glaze, however, dry, crack and fall off. I was looking to calcinate
> the
> barnard's by itself but wonder if I could just calcinate the mixture
> instead
> since I have a bunch of this already made up. The question goes a little
> deeper though and I would like to ask whether calcinating a glaze batch
> would cause any problems versus calcinating just a specific ingredient.
> Thanks to all who offer their opinions and experience.

Thomas G. Sawyer, M.D., J.D. on mon 23 may 11


Thanks Paul. No calcinated acrimony here. [see previous note on acrimony
instead of antimony]. Funny what comes out of our fingertips.

-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of Paul Lewing
Sent: Sunday, May 22, 2011 7:08 PM
To: Clayart@LSV.CERAMICS.ORG
Subject: Re: Calcination of Glaze vs specific ingredient

On May 22, 2011, at 7:46 AM, Thomas G. Sawyer, M.D., J.D. wrote:

wonder if I could just calcinate the mixture instead
since I have a bunch of this already made up.

You could do that and it wouldn't make any difference. The frit is
essentially already calcined. Incidentally, the word is calcine, not
calcinate, but then I'm a grammar Nazi. Sorry.

Paul Lewing
www.paullewingtile.com
www.paullewingart.com




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Paul Lewing on mon 23 may 11


On May 22, 2011, at 2:38 PM, Paul Herman wrote:

I would calcine the Barnard separately, because the frit 3134 has a
very low melting point. I would think if you calcine the combination,
it would fuse

You're probably right about that. I forgot when I posted my message
saying that it might help that most potters calcine in a bisque
firing, to cone 08 or so. I do mine in a china paint firing to 016.
It doesn't matter in this instance what temperature you calcine to, as
long as you go above red heat to drive off the chemically combined
water.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com

David Woof on wed 25 may 11


Hi Tom=3D2C
=3D20
Snail is right on. =3D20
=3D20
Here is another addition to this line of reasoning: If I calcined anything=
=3D
it would be the clays in the glazes you are putting on top of the Ebony. =
=3D
Top layer glazes of higher clay content tend to shrink=3D2C crack=3D2C curl=
=3D2C =3D
flake and peel off base glazes=3D2C especially as Snail says if they are po=
wd=3D
ery. ( Usually from High frit content) (and when not using gums and bentoni=
=3D
te) I strongly support using CMC gum and bentonite in all glazes and=3D3B =
e=3D
xcept in rare instances where a flocculent is needed (example: where a body=
=3D
needs a higher bisque) to learn to deflocculate your glazes as well. Good=
=3D
sense ease of application=3D2C acts in concert with the CMC and bentonite =
to=3D
keep your ingrediants in suspension=3D2C and little to no caking and hard =
pa=3D
n in storage!!! Good sense if you do/stupid if you don't!!! Check the Ar=
=3D
chives. It has all been discussed to "death" and laid out clearly. =3D20
=3D20
And if I have offended anyone's pet or fav way of doing things=3D2C I don'=
t =3D
apologize=3D3B perhaps its time to think=3D2C do=3D2C or try something new=
or di=3D
fferent that you haven't been repeating from a book you read 40 years ago o=
=3D
r heard some long dead teacher speak to a rapt audience of beginners as gos=
=3D
pel. Clay science is moving on=3D3B we must stay off our arses and on our =
fe=3D
et!!! We really haven't yet dug very deep into the mountain of possibiliti=
=3D
es.
=3D20
David Woof
=3D20
Messages in this topic (7)
________________________________________________________________________
5b. Re: Calcination of Glaze vs specific ingredient
Posted by: "Snail Scott" claywork@FLYING-SNAIL.COM=3D20
Date: Sun May 22=3D2C 2011 4:57 pm ((PDT))

On May 22=3D2C 2011=3D2C at 9:46 AM=3D2C Thomas G. Sawyer=3D2C M.D.=3D2C J.=
D. wrote:
> ...a fairly nice glaze by itself but
> works really good under other glazes. A fair number of glaze one uses as =
=3D
the
> top glaze=3D2C however=3D2C dry=3D2C crack and fall off...


Often=3D2C when the second coating flakes off=3D2C it's
because the underlayer is dusty and/or fragile.=3D20
You can add gum or bentonite to help harden the=3D20
base coat=3D2C or bisque the base coat in place so=3D20
that it won't be powdery when the top coat goes=3D20
on. (You can re-bisque to a low temp=3D2C or apply=3D20
the bottom glaze while the clay is still green.)
___________________________________________________________________________=
=3D
_________
=3D20
5a. Calcination of Glaze vs specific ingredient
Posted by: "Thomas G. Sawyer=3D2C M.D.=3D2C J.D." tsawyer@CFL.RR.COM=3D20
Date: Sun May 22=3D2C 2011 2:00 pm ((PDT))

Some time ago I obtained a glaze from clayart called ebony=3D3B it consists=
o=3D
f
50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself but
works really good under other glazes. A fair number of glaze one uses as th=
=3D
e
top glaze=3D2C however=3D2C dry=3D2C crack and fall off. I was looking to c=
alcina=3D
te the
barnard's by itself but wonder if I could just calcinate the mixture instea=
=3D
d
since I have a bunch of this already made up. The question goes a little
deeper though and I would like to ask whether calcinating a glaze batch
would cause any problems versus calcinating just a specific ingredient.
Thanks to all who offer their opinions and experience.



Tom Sawyer
=3D20

=3D20




=3D

May Luk on thu 26 may 11


Hello Thomas:

I have been thinking about your problem because I am visualizing all
the bubbles coming up when I double dip a glaze and try to figure out
what is going on. Then I googled and found this article:-

http://www.hedon.info/BP31_EffectsOfTheClay-NonClayRatioOnStoveBehaviour

This is about clay body but all the same, it explains how clay shrinks
& clay/no clay ratios:
"With a higher proportion of clay mineral in the green ceramic, it
will shrink more during drying. The tendency for splits to occur will
increase with increased shrinkage because shrinkage occurs
non-uniformly with non-uniform drying. This causes stresses to
develop, which can be relieved by the formation of fissures or
splits.The larger fissures will not heal during firing."

I learned a new word "anisotropic" (I still have to read "Anisotropy
of shrinkage and residual stress development" slowly later)

Thanks for the question and the learning opportunity

May
Brooklyn NY


On Sun, May 22, 2011 at 10:46 AM, Thomas G. Sawyer, M.D., J.D.
wrote:
> Some time ago I obtained a glaze from clayart called ebony; it consists o=
f
> 50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself bu=
t
> works really good under other glazes. A fair number of glaze one uses as =
the
> top glaze, however, dry, crack and fall off. I was looking to calcinate t=
he
> barnard's by itself but wonder if I could just calcinate the mixture inst=
ead
> since I have a bunch of this already made up. The question goes a little
> deeper though and I would like to ask whether calcinating a glaze batch
> would cause any problems versus calcinating just a specific ingredient.
> Thanks to all who offer their opinions and experience.
>
>
>
> Tom Sawyer

--
http://twitter.com/MayLuk
http://www.takemehomeware.com/

David Woof on mon 30 may 11


Hi Steve=3D2C
Are you speaking of Wood ash? If so=3D2C I am curious about your ash based=
g=3D
lazes: is/are these formulated as a glaze in that there is a balance of mat=
=3D
erials that allow them to work as a stand alone glazes=3D2C and if so=3D2C =
what=3D
is your vehicular medium. If otherwise: what/why are you doing what you a=
=3D
re doing=3D2C and how do you handle it from glazing application to kiln loa=
di=3D
ng for firing.
=3D20
Woof
____________________________________________________________=3D20
=3D20
Steve Mills wrote: t=3D
he glazes I currently use are Ash based and contain no clay=3D2C gum=3D2C o=
r be=3D
ntonite. Consequently most (but not all) work very well in layers over more=
=3D
conventionally constructed glazes.>

Steve M

Bath
UK

David Woof wrote:

>Hi Tom=3D2C
>=3D20
>Snail is right on.=3D20
>=3D20
>Here is another addition to this line of reasoning: If I calcined anything=
=3D
it would be the clays in the glazes you are putting on top of the Ebony. T=
=3D
op layer glazes of higher clay content tend to shrink=3D2C crack=3D2C curl=
=3D2C f=3D
lake and peel off base glazes=3D2C especially as Snail says if they are pow=
de=3D
ry. ( Usually from High frit content) (and when not using gums and bentonit=
=3D
e) I strongly support using CMC gum and bentonite in all glazes and=3D3B ex=
ce=3D
pt in rare instances where a flocculent is needed (example: where a body ne=
=3D
eds a higher bisque) to learn to deflocculate your glazes as well. Good sen=
=3D
se ease of application=3D2C acts in concert with the CMC and bentonite to k=
ee=3D
p your ingrediants in suspension=3D2C and little to no caking and hard pan =
in=3D
storage!!! Good sense if you do/stupid if you don't!!! Check the Archives.=
=3D
It has all been discussed to "death" and laid out clearly.=3D20
>=3D20
>And if I have offended anyone's pet or fav way of doing things=3D2C I don'=
t =3D
apologize=3D3B perhaps its time to think=3D2C do=3D2C or try something new =
or dif=3D
ferent that you haven't been repeating from a book you read 40 years ago or=
=3D
heard some long dead teacher speak to a rapt audience of beginners as gosp=
=3D
el. Clay science is moving on=3D3B we must stay off our arses and on our fe=
et=3D
!!! We really haven't yet dug very deep into the mountain of possibilities.
>=3D20
>David Woof
>=3D20
>Messages in this topic (7)
>________________________________________________________________________
>5b. Re: Calcination of Glaze vs specific ingredient
>Posted by: "Snail Scott" claywork@FLYING-SNAIL.COM=3D20
>Date: Sun May 22=3D2C 2011 4:57 pm ((PDT))
>
>On May 22=3D2C 2011=3D2C at 9:46 AM=3D2C Thomas G. Sawyer=3D2C M.D.=3D2C J=
.D. wrote:
>> ...a fairly nice glaze by itself but
>> works really good under other glazes. A fair number of glaze one uses as=
=3D
the
>> top glaze=3D2C however=3D2C dry=3D2C crack and fall off...
>
>
>Often=3D2C when the second coating flakes off=3D2C it's
>because the underlayer is dusty and/or fragile.=3D20
>You can add gum or bentonite to help harden the=3D20
>base coat=3D2C or bisque the base coat in place so=3D20
>that it won't be powdery when the top coat goes=3D20
>on. (You can re-bisque to a low temp=3D2C or apply=3D20
>the bottom glaze while the clay is still green.)
>__________________________________________________________________________=
=3D
__________
>=3D20
>5a. Calcination of Glaze vs specific ingredient
>Posted by: "Thomas G. Sawyer=3D2C M.D.=3D2C J.D." tsawyer@CFL.RR.COM=3D20
>Date: Sun May 22=3D2C 2011 2:00 pm ((PDT))
>
>Some time ago I obtained a glaze from clayart called ebony=3D3B it consist=
s =3D
of
>50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself but
>works really good under other glazes. A fair number of glaze one uses as t=
=3D
he
>top glaze=3D2C however=3D2C dry=3D2C crack and fall off. I was looking to =
calcin=3D
ate the
>barnard's by itself but wonder if I could just calcinate the mixture inste=
=3D
ad
>since I have a bunch of this already made up. The question goes a little
>deeper though and I would like to ask whether calcinating a glaze batch
>would cause any problems versus calcinating just a specific ingredient.
>Thanks to all who offer their opinions and experience.
>
>
>
>Tom Sawyer
>=3D20


=3D20



=3D

Steve Mills on tue 31 may 11


Hi David,
Yes they are wood ash. I didn't formulate the recipe, I can't; private educ=
a=3D
tion ie BBC accent, no maths, the recipe is a Nuka one I found on the net; =
R=3D
ice Husk Ash, Silica, and Feldspar, only I sub single species wood ash for =
t=3D
he Rice Husk, and ball mill it thoroughly (home made ball mill). Water is =
t=3D
he carrier, and it holds well on any surface because it's fine ground.=3D20
Very simple really, which suits me!

Best

Steve M

Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my Ipod touch

On 30 May 2011, at 20:25, David Woof wrote:

> Hi Steve,
> Are you speaking of Wood ash? If so, I am curious about your ash based g=
l=3D
azes: is/are these formulated as a glaze in that there is a balance of mate=
r=3D
ials that allow them to work as a stand alone glazes, and if so, what is yo=
u=3D
r vehicular medium. If otherwise: what/why are you doing what you are doin=
g=3D
, and how do you handle it from glazing application to kiln loading for fir=
i=3D
ng.
>=3D20
> Woof
> ____________________________________________________________=3D20
>=3D20
> Steve Mills wrote: h=3D
e glazes I currently use are Ash based and contain no clay, gum, or bentoni=
t=3D
e. Consequently most (but not all) work very well in layers over more conve=
n=3D
tionally constructed glazes.>
>=3D20
> Steve M
>=3D20
> Bath
> UK
>=3D20
> David Woof wrote:
>=3D20
>> Hi Tom,
>>=3D20
>> Snail is right on.=3D20
>>=3D20
>> Here is another addition to this line of reasoning: If I calcined anythi=
n=3D
g it would be the clays in the glazes you are putting on top of the Ebony. =
T=3D
op layer glazes of higher clay content tend to shrink, crack, curl, flake a=
n=3D
d peel off base glazes, especially as Snail says if they are powdery. ( Usu=
a=3D
lly from High frit content) (and when not using gums and bentonite) I stron=
g=3D
ly support using CMC gum and bentonite in all glazes and; except in rare in=
s=3D
tances where a flocculent is needed (example: where a body needs a higher b=
i=3D
sque) to learn to deflocculate your glazes as well. Good sense ease of appl=
i=3D
cation, acts in concert with the CMC and bentonite to keep your ingrediants=
i=3D
n suspension, and little to no caking and hard pan in storage!!! Good sense=
i=3D
f you do/stupid if you don't!!! Check the Archives. It has all been discuss=
e=3D
d to "death" and laid out clearly.=3D20
>>=3D20
>> And if I have offended anyone's pet or fav way of doing things, I don't =
a=3D
pologize; perhaps its time to think, do, or try something new or different =
t=3D
hat you haven't been repeating from a book you read 40 years ago or heard s=
o=3D
me long dead teacher speak to a rapt audience of beginners as gospel. Clay =
s=3D
cience is moving on; we must stay off our arses and on our feet!!! We reall=
y=3D
haven't yet dug very deep into the mountain of possibilities.
>>=3D20
>> David Woof
>>=3D20
>> Messages in this topic (7)
>> ________________________________________________________________________
>> 5b. Re: Calcination of Glaze vs specific ingredient
>> Posted by: "Snail Scott" claywork@FLYING-SNAIL.COM=3D20
>> Date: Sun May 22, 2011 4:57 pm ((PDT))
>>=3D20
>> On May 22, 2011, at 9:46 AM, Thomas G. Sawyer, M.D., J.D. wrote:
>>> ...a fairly nice glaze by itself but
>>> works really good under other glazes. A fair number of glaze one uses a=
s=3D
the
>>> top glaze, however, dry, crack and fall off...
>>=3D20
>>=3D20
>> Often, when the second coating flakes off, it's
>> because the underlayer is dusty and/or fragile.=3D20
>> You can add gum or bentonite to help harden the=3D20
>> base coat, or bisque the base coat in place so=3D20
>> that it won't be powdery when the top coat goes=3D20
>> on. (You can re-bisque to a low temp, or apply=3D20
>> the bottom glaze while the clay is still green.)
>> ________________________________________________________________________=
_=3D
___________
>>=3D20
>> 5a. Calcination of Glaze vs specific ingredient
>> Posted by: "Thomas G. Sawyer, M.D., J.D." tsawyer@CFL.RR.COM=3D20
>> Date: Sun May 22, 2011 2:00 pm ((PDT))
>>=3D20
>> Some time ago I obtained a glaze from clayart called ebony; it consists =
o=3D
f
>> 50% 3134 Frit and 50% Barnard's. This is a fairly nice glaze by itself b=
u=3D
t
>> works really good under other glazes. A fair number of glaze one uses as=
t=3D
he
>> top glaze, however, dry, crack and fall off. I was looking to calcinate =
t=3D
he
>> barnard's by itself but wonder if I could just calcinate the mixture ins=
t=3D
ead
>> since I have a bunch of this already made up. The question goes a little
>> deeper though and I would like to ask whether calcinating a glaze batch
>> would cause any problems versus calcinating just a specific ingredient.
>> Thanks to all who offer their opinions and experience.
>>=3D20
>>=3D20
>>=3D20
>> Tom Sawyer
>>=3D20
>=3D20
>=3D20
>=3D20
>=3D20
>=3D20
>=3D20

Lee on tue 31 may 11


Tom,

Have you tried the slip glaze on the pot before you bisque?
Leather or raw glazed, depending on the claybody. (tight bodies glaze
green okay.) Sounds like it might work as a single fire glaze.

After the bisque, you could add the second glaze.

--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/

=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue