Linda Knapp on wed 13 nov 02
(Sorry if this is a duplicate - My computer passed gas in the midst of writing this....)
I have been trying to come up with a cone 10 clear glaze for Stoneware which does not craze. I am using the Cone 10 Transparenet from Insight:
EPK 20.5
Silica 26.5
Custer 27
Wollastonite 23.5
Zinc 2.5
It currently fits our porcelain but crazes like crazy on stoneware. Anyone have any suggestions? I am going to run tests tonight.
Linda
From the presently wet but not flooded Seattle
linda@bozuk.org
Mary White on wed 13 nov 02
Linda--
I had the same experience with the Insight glaze on white stoneware
(B-mix). A friend of mine who is a professional potter gave me this
one, it's her standard clear glaze and she uses B-mix. I've only
tried it once, just a couple of days ago, and it looks fine (^10R).
Whiting 11
Custer 36
Bentonite 3
EPK 18
Silica 23
Dolomite 9
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mary
on the wet west coast of British Columbia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>(Sorry if this is a duplicate - My computer passed gas in the midst
>of writing this....)
>
>I have been trying to come up with a cone 10 clear glaze for
>Stoneware which does not craze. I am using the Cone 10 Transparenet
>from Insight:
>
>EPK 20.5
>Silica 26.5
>Custer 27
>Wollastonite 23.5
>Zinc 2.5
>
>It currently fits our porcelain but crazes like crazy on stoneware.
>Anyone have any suggestions? I am going to run tests tonight.
>
>Linda
>>From the presently wet but not flooded Seattle
>linda@bozuk.org
>
>______________________________________________________________________________
>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
>melpots@pclink.com.
--
Ababi on thu 14 nov 02
Hello Linda
If you read well Tony Hansen's book you would read about glaze fit to the claybody or
not to use "text books" I wrote to Tony Hansen and told him the "texts books, the
glazes recipes books helped me to learn the glazes. Tony wrote back and explained
me he meant not to use these recipes blindly without understanding them, in my
words, making the recipes from white powders with different names, not knowing
what these powder really are. In general I agree with Tony.
This glaze you have found in Tony Hansen's software, I am sure is reliable, be cause
the developer is a very responsible person.
Now after the compliments: This is what i do:
After testing (Including raku until recently) I bring home to the computer all the test
plus the recipes pages where I have written my notes.
I look in the test bar or saucer as I test lately and see what the numbers are telling
expansion,
Si:al
Amount of mol parts
and so on. I am sure that now, from Israel I can make you, using insight, or Matrix a
good ^10 glaze even I never fired that high. but this is not the point. The point is: you
have to see the results yourself compare it with other glazes you made before!
In the Glaze Simulator, a software I cannot recommend ( Sorry Fraser ) There is an
interesting way to solve it. The program asks you to choose some good glazes to
adjust itself to your kiln.
I think one can adjust its knowledge and 'communication' to hers/his software the way
I explained you before!
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
localpotter@walla.co.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
---------- Original Message ----------
>Linda--
>I had the same experience with the Insight glaze on white stoneware
>(B-mix). A friend of mine who is a professional potter gave me this
>one, it's her standard clear glaze and she uses B-mix. I've only
>tried it once, just a couple of days ago, and it looks fine (^10R).
>Whiting 11
>Custer 36
>Bentonite 3
>EPK 18
>Silica 23
>Dolomite 9
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Mary
>on the wet west coast of British Columbia
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>(Sorry if this is a duplicate - My computer passed gas in the midst
>>of writing this....)
>>
>>I have been trying to come up with a cone 10 clear glaze for
>>Stoneware which does not craze. I am using the Cone 10 Transparenet
>>from Insight:
>>
>>EPK 20.5
>>Silica 26.5
>>Custer 27
>>Wollastonite 23.5
>>Zinc 2.5
>>
>>It currently fits our porcelain but crazes like crazy on stoneware.
>>Anyone have any suggestions? I am going to run tests tonight.
>>
>>Linda
>>>From the presently wet but not flooded Seattle
>>linda@bozuk.org
>>
>>______________________________________________________________________________
>>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
>>melpots@pclink.com.
>--
>______________________________________________________________________________
>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 melpots@pclink.com.
Tom Buck on thu 14 nov 02
---------- Forwarded message ----------
Date: Thu, 14 Nov 2002 10:47:26 -0500 (EST)
From: Tom Buck
To: Linda Knapp
Subject: Re: Help with Glaze Craze needed
Hi again, Linda:
what is it with this BMix claybody? seems to give problems. if it
has a greater expansion/contraction than a typical porcelain, then it is
peculiar. most C10R clears craze on the porcelain, not the SW.
You gave this recipe:
EPK / Silica / Wollastonite / Custer fs / Zinc oxide
20.5 / 26.5 / 23.5 / 27 / 2.5
Firstly, know that the Zinc Oxide (ZnO) is along for the ride. It soon
disappears up the flue. BUT, it might help melting early on before it
leaves the scene.
The Seger is as follows:
CaO 0.7 / MgO 0.04 / K2O 0.12 / Na2O / Al2O3 0.55 / SiO2 4.63
with a SiO2/Al2O3 ratio of 8.4 and a COE (UK values) of 390
With 0.11 moles of ZnO included, the ratio goes to 9 & COE to 400.
These Seger values say the glaze should fit most SWs.
1st revision:
EPK / Woll. / Custer / Silica / Talc NY
16 / 16 / 36 / 27 / 5
CaO 0.58 / MgO 0.16 / K2O 0.18 / Ma2O 0.08 / Al2O3 0.55 / SiO2 5.23
Ratio = 9.5 COE 380
glossy, should fit.
2nd Revision
Woll / Custer / EPK / Silica
21 / 36 / 16 / 27
CaO 0.71 / MgO 0.04 / K2O 0.17 / Na2O 0.08 / Al2O3 0.55 / SiO2 5.18
R= 9.5 COE = 405
according to your data this should craze on BMix. try it and let me know
please.
One problem you might be having is that the BMix is not mature at C10, and
is open enough to allow moisture crazing/cracking. So, try firing to C11R,
perhaps C12R.
that's it for now. peace. Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
Linda Knapp on thu 14 nov 02
A follow on to this earlier post-
First of all thanks to everyone who has been sending me pointers - I
read most late last night after spending the day in the studio doing an
Ian Curtis style grid on this glaze. I'll let everyone know my results -
although it was my first grid so buyer beware ;-) I think if I do a grid
again I will not do a full 35 test but perhaps a diaganol and maybe a
grouping around any interest points. The full test was way too much time
and effort- especially for one person alone.
I did stupidly leave off a data point - I really fire to ^11R in a gas
kiln.
On a different subject what methodology to people use to convert recipes
from one cone to another? Do you just calculate them with different
limit formulas?
Again thanks for all the help - I'll let everyone know in a couple days
when the tests come out how they did.
Linda
Linda Knapp wrote:
>(Sorry if this is a duplicate - My computer passed gas in the midst of writing this....)
>
>I have been trying to come up with a cone 10 clear glaze for Stoneware which does not craze. I am using the Cone 10 Transparenet from Insight:
>
>EPK 20.5
>Silica 26.5
>Custer 27
>Wollastonite 23.5
>Zinc 2.5
>
>It currently fits our porcelain but crazes like crazy on stoneware. Anyone have any suggestions? I am going to run tests tonight.
>
>Linda
>>From the presently wet but not flooded Seattle
>linda@bozuk.org
>
>
David Hewitt on thu 14 nov 02
The standard approach would be to add more silica. Adding 40 parts
instead of 26.5 makes a significant reduction in the glaze calculated
coefficient of expansion.
My experience has been that the porcelain clay I use is more likely to
craze than the stoneware I use. If only suppliers would publish the clay
expansion figure we would surely find things a lot easier.
David
In message , Linda Knapp writes
>(Sorry if this is a duplicate - My computer passed gas in the midst of wr=
>iting this....)
>
>I have been trying to come up with a cone 10 clear glaze for Stoneware wh=
>ich does not craze. I am using the Cone 10 Transparenet from Insight:
>
>EPK 20.5
>Silica 26.5
>Custer 27
>Wollastonite 23.5
>Zinc 2.5
>
>It currently fits our porcelain but crazes like crazy on stoneware. Anyon=
>e have any suggestions? I am going to run tests tonight.
>
>Linda
>=46rom the presently wet but not flooded Seattle
>linda@bozuk.org
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Christena Schafale on thu 14 nov 02
Linda,
Just a note about the Ian Currie blends -- the first few that you do are
MUCH more time-consuming than they will be when you get used to the
method. I had done one at a workshop, and one with a friend, and both took
at least half a day. Then I did about 8 this summer, and they got easier
and quicker with each try. For some things, you really don't need the
whole grid, but for exploring alumina/silica variations around a recipe,
they're wonderful.
Chris
At 08:40 AM 11/14/02 -0800, you wrote:
> A follow on to this earlier post-
>
>First of all thanks to everyone who has been sending me pointers - I
>read most late last night after spending the day in the studio doing an
>Ian Curtis style grid on this glaze. I'll let everyone know my results -
>although it was my first grid so buyer beware ;-) I think if I do a grid
>again I will not do a full 35 test but perhaps a diaganol and maybe a
>grouping around any interest points. The full test was way too much time
>and effort- especially for one person alone.
Consultation and Referral Specialist
Resources for Seniors
christenas@rfsnc.org
http://www.resourcesforseniors.com
Phone: (919) 713-1537
FAX: (919) 872-9574
1110 Navaho Dr, Suite 400
Raleigh, NC 27609
Linda Knapp on sat 16 nov 02
Well I got the grid test out of the kiln today. I must say my head
hurt after looking at it!
(For those of you who do not have the Currie book you can go to his
website http://www.currie.to to follow along, I am using his grid number
system.)
I did a standard Ian Currie Grid test with a base recipe of:
Custer Feldspar - 270
Wollastonite - 235
Zinc - 25
I did the test using both our standard Porcelain and Stoneware Fired to
Cone 11 Reduction.
The crazing results were:
Porcelain:
Wide spaced crazing in squares: 11, 16, 21, 22
Medium spaced crazing in squares: 26, 27, 31, 32, 33
All other squares no crazing
Stoneware:
No crazing in: 1,2, 3, 4, 5, 7, 8, 9, 10
Crazing in all other squares.
The thing that makes me crazy is the pattern of crazing:
In all cases the crazing got finer as the Silica increased. For instance
in squares 16 -> 20 the crazing gets finer as you go from 16 to 20.
What makes my head hurt is: Conventional wisdom says that crazing gets
bigger before it goes away. Conventional wisdom also says that adding
silica helps make crazing go away. (I know - not always) In the case of
porcelain this seems to hold true. Square 21 has wide crazing, 22 has a
very small amount of very wide crazing, 23 has no crazing. For the
stoneware though it seems to be exactly opposite.
I am still considering the results but I plan to do some tests around
square 8 on our stoneware - It is not a great looking glaze test but is
ok and not crazed. I want to see what it will look like on a bigger test.
Linda
Linda Knapp wrote:
> A follow on to this earlier post-
>
> First of all thanks to everyone who has been sending me pointers - I
> read most late last night after spending the day in the studio doing an
> Ian Curtis style grid on this glaze. I'll let everyone know my results -
> although it was my first grid so buyer beware ;-) I think if I do a grid
> again I will not do a full 35 test but perhaps a diaganol and maybe a
> grouping around any interest points. The full test was way too much time
> and effort- especially for one person alone.
>
> I did stupidly leave off a data point - I really fire to ^11R in a gas
> kiln.
>
> On a different subject what methodology to people use to convert recipes
> from one cone to another? Do you just calculate them with different
> limit formulas?
>
> Again thanks for all the help - I'll let everyone know in a couple days
> when the tests come out how they did.
>
> Linda
>
> Linda Knapp wrote:
>
>> (Sorry if this is a duplicate - My computer passed gas in the midst
>> of writing this....)
>>
>> I have been trying to come up with a cone 10 clear glaze for
>> Stoneware which does not craze. I am using the Cone 10 Transparenet
>> from Insight:
>>
>> EPK 20.5
>> Silica 26.5
>> Custer 27
>> Wollastonite 23.5
>> Zinc 2.5
>>
>> It currently fits our porcelain but crazes like crazy on stoneware.
>> Anyone have any suggestions? I am going to run tests tonight.
>>
>> Linda
>>
>>> From the presently wet but not flooded Seattle
>>
>> linda@bozuk.org
>>
>>
>
> ______________________________________________________________________________
>
> 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
> melpots@pclink.com.
Linda Rosen on sat 16 nov 02
from one Linda to another
I am thinking that a Currie test on a typical Currie grid might not be the
best choice when you are trying to sort out crazing questions . Crazing is
the result of stress build up and tiny samples just don't have the same
stresses. You could apply the same volumetric idea as used in the Currie
method but need sizable tests for information worth analysing. This would
be especially true where the craze pattern would be large (or almost
solved).
Linda Rosen,
Toronto, on a very "November" day
> -----Original Message-----
> From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
> Behalf Of Linda Knapp
> Sent: November 16, 2002 3:01 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Help with Glaze Craze needed
>
>
> Well I got the grid test out of the kiln today. I must say my head
> hurt after looking at it!
>
> (For those of you who do not have the Currie book you can go to his
> website http://www.currie.to to follow along, I am using his grid number
> system.)
>
> I did a standard Ian Currie Grid test with a base recipe of:
> Custer Feldspar - 270
> Wollastonite - 235
> Zinc - 25
>
> I did the test using both our standard Porcelain and Stoneware Fired to
> Cone 11 Reduction.
>
> The crazing results were:
>
> Porcelain:
>
> Wide spaced crazing in squares: 11, 16, 21, 22
> Medium spaced crazing in squares: 26, 27, 31, 32, 33
> All other squares no crazing
>
> Stoneware:
>
> No crazing in: 1,2, 3, 4, 5, 7, 8, 9, 10
> Crazing in all other squares.
> The thing that makes me crazy is the pattern of crazing:
> In all cases the crazing got finer as the Silica increased. For instance
> in squares 16 -> 20 the crazing gets finer as you go from 16 to 20.
> What makes my head hurt is: Conventional wisdom says that crazing gets
> bigger before it goes away. Conventional wisdom also says that adding
> silica helps make crazing go away. (I know - not always) In the case of
> porcelain this seems to hold true. Square 21 has wide crazing, 22 has a
> very small amount of very wide crazing, 23 has no crazing. For the
> stoneware though it seems to be exactly opposite.
>
> I am still considering the results but I plan to do some tests around
> square 8 on our stoneware - It is not a great looking glaze test but is
> ok and not crazed. I want to see what it will look like on a bigger test.
>
> Linda
>
> Linda Knapp wrote:
>
> > A follow on to this earlier post-
> >
> > First of all thanks to everyone who has been sending me pointers - I
> > read most late last night after spending the day in the studio doing an
> > Ian Curtis style grid on this glaze. I'll let everyone know my results -
> > although it was my first grid so buyer beware ;-) I think if I do a grid
> > again I will not do a full 35 test but perhaps a diaganol and maybe a
> > grouping around any interest points. The full test was way too much time
> > and effort- especially for one person alone.
> >
> > I did stupidly leave off a data point - I really fire to ^11R in a gas
> > kiln.
> >
> > On a different subject what methodology to people use to convert recipes
> > from one cone to another? Do you just calculate them with different
> > limit formulas?
> >
> > Again thanks for all the help - I'll let everyone know in a couple days
> > when the tests come out how they did.
> >
> > Linda
> >
> > Linda Knapp wrote:
> >
> >> (Sorry if this is a duplicate - My computer passed gas in the midst
> >> of writing this....)
> >>
> >> I have been trying to come up with a cone 10 clear glaze for
> >> Stoneware which does not craze. I am using the Cone 10 Transparenet
> >> from Insight:
> >>
> >> EPK 20.5
> >> Silica 26.5
> >> Custer 27
> >> Wollastonite 23.5
> >> Zinc 2.5
> >>
> >> It currently fits our porcelain but crazes like crazy on stoneware.
> >> Anyone have any suggestions? I am going to run tests tonight.
> >>
> >> Linda
> >>
> >>> From the presently wet but not flooded Seattle
> >>
> >> linda@bozuk.org
> >>
> >>
> >
> >
> __________________________________________________________________
> ____________
> >
> > 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
> > melpots@pclink.com.
>
> __________________________________________________________________
> ____________
> 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
> melpots@pclink.com.
>
| |
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