Linda Pahl on fri 20 feb 04
Hi all.
I am new to formulating glazes. I finally had Juicy Turquoise, the
first glaze I formulated, tested for copper and lithium leaching and
the results are in. Thought I should post the results since I've
already posted the glaze recipe.
Glaze name: Juicy Turquoise
Cone: 6
Color: turquoise
Surface texture: semi-gloss
Firing: oxidation
Comments: breaks to red/brown on texture and edges; looks best on iron
clay body. Mix to consistency of heavy cream and apply heavily for
best color.
click here to see a photo of the glaze:
http://home.earthlink.net/~jessieadair/tests/
Cornwall Stone 41.00
Kentucky Ball Clay (OM 4) 10.00
EPK 5.00
Lithium Carbonate 5.00
Strontium Carbonate 12.50
Whiting 10.00
Flint 16.50
Totals: 100.00 %
Also add:
Copper Oxide 2.50
Tin Oxide 4.50
Bentonite 2.00
Unity Formula for Juicy Turquoise:
0.056 K2O 0.354 Al2O3 2.909 SiO2
0.080 Na2O 0.004 Fe2O3 0.007 TiO2
0.366 CaO 0.005 P2O5 8.2:1 Si:Al Ratio
0.006 MgO
0.218 Li2O
0.273 SrO
Percentage Analysis for Juicy Turquoise:
62.73 % SiO2
12.96 % Al2O3
1.89 % K2O
1.78 % Na2O
7.37 % CaO
0.09 % MgO
2.34 % Li2O
10.16 % SrO
0.23 % Fe2O3
0.25 % P2O5
0.20 % TiO2
Results of lab testing for lithium and copper: Lithium 0.32 mg/L and
copper 11.2 mg/L
The copper is higher than I hoped for (was hoping for 5 or below) so I
wouldn't use this glaze on surfaces that come in contact with food.
Thanks to helpful suggestions from John Hesselberth, I have a few
things I can change in order to try and get better results:
1) add some boron (about 0.3) to help with the melt;
2) increase silica to about 3.0 (now it's at about 2.8) to increase
stability; and
3) source lithium from spodumene (less soluble source of lithium) to
help avoid the possibility of shivering
I will try and retain the lovely turquoise color as I make my changes
to the recipe so I have my work cut out for me as that is a difficult
color to achieve. The process from formulating to testing is one that
takes some time (but well worth the time and effort) so it will be a
while before I have the new results in.
Regards,
Linda Pahl, Kew Gardens, New York
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
email: TheClosetPotter@earthlink.net
website: http://home.earthlink.net/~jessieadair/tests/
///////////////////////////////////////////////////////////////
Mildred Herot on fri 20 feb 04
Hi Linda: Reading your message brought to mind a question I would really
like answered. I like to layer glazes and usually brush and stipple a glaze
on greenware and, after the bisque, spray on another glaze for the mix. If
the second glaze is a safe one, will that negate the problem with the first
if the first is not food safe? Hope I made myself clear.....Mildred Herot
----- Original Message -----
From: "Linda Pahl"
To:
Sent: Friday, February 20, 2004 2:43 PM
Subject: ^6 Juicy Turquoise Glaze: lab test results
> Hi all.
>
> I am new to formulating glazes. I finally had Juicy Turquoise, the
> first glaze I formulated, tested for copper and lithium leaching and
> the results are in. Thought I should post the results since I've
> already posted the glaze recipe.
>
> Glaze name: Juicy Turquoise
> Cone: 6
> Color: turquoise
> Surface texture: semi-gloss
> Firing: oxidation
> Comments: breaks to red/brown on texture and edges; looks best on iron
> clay body. Mix to consistency of heavy cream and apply heavily for
> best color.
>
> click here to see a photo of the glaze:
> http://home.earthlink.net/~jessieadair/tests/
>
> Cornwall Stone 41.00
> Kentucky Ball Clay (OM 4) 10.00
> EPK 5.00
> Lithium Carbonate 5.00
> Strontium Carbonate 12.50
> Whiting 10.00
> Flint 16.50
> Totals: 100.00 %
>
> Also add:
> Copper Oxide 2.50
> Tin Oxide 4.50
> Bentonite 2.00
>
> Unity Formula for Juicy Turquoise:
> 0.056 K2O 0.354 Al2O3 2.909 SiO2
> 0.080 Na2O 0.004 Fe2O3 0.007 TiO2
> 0.366 CaO 0.005 P2O5 8.2:1 Si:Al Ratio
> 0.006 MgO
> 0.218 Li2O
> 0.273 SrO
>
> Percentage Analysis for Juicy Turquoise:
> 62.73 % SiO2
> 12.96 % Al2O3
> 1.89 % K2O
> 1.78 % Na2O
> 7.37 % CaO
> 0.09 % MgO
> 2.34 % Li2O
> 10.16 % SrO
> 0.23 % Fe2O3
> 0.25 % P2O5
> 0.20 % TiO2
>
>
> Results of lab testing for lithium and copper: Lithium 0.32 mg/L and
> copper 11.2 mg/L
>
> The copper is higher than I hoped for (was hoping for 5 or below) so I
> wouldn't use this glaze on surfaces that come in contact with food.
>
> Thanks to helpful suggestions from John Hesselberth, I have a few
> things I can change in order to try and get better results:
>
> 1) add some boron (about 0.3) to help with the melt;
> 2) increase silica to about 3.0 (now it's at about 2.8) to increase
> stability; and
> 3) source lithium from spodumene (less soluble source of lithium) to
> help avoid the possibility of shivering
>
> I will try and retain the lovely turquoise color as I make my changes
> to the recipe so I have my work cut out for me as that is a difficult
> color to achieve. The process from formulating to testing is one that
> takes some time (but well worth the time and effort) so it will be a
> while before I have the new results in.
>
> Regards,
>
> Linda Pahl, Kew Gardens, New York
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> email: TheClosetPotter@earthlink.net
> website: http://home.earthlink.net/~jessieadair/tests/
>
> ///////////////////////////////////////////////////////////////
>
>
____________________________________________________________________________
__
> 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 Sharon on sat 21 feb 04
I wonder Linda.
Is it my dark monitor that makes your turquoise brown or you are not
adjusting the colors?
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
To Ceramics forum in Hebrew:
http://www.botzpottery.co.il/kishurim.html
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Linda Pahl
Sent: Friday, February 20, 2004 9:44 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: ^6 Juicy Turquoise Glaze: lab test results
Hi all.
I am new to formulating glazes. I finally had Juicy Turquoise, the
first glaze I formulated, tested for copper and lithium leaching and
the results are in. Thought I should post the results since I've
already posted the glaze recipe.
Glaze name: Juicy Turquoise
Cone: 6
Color: turquoise
Surface texture: semi-gloss
Firing: oxidation
Comments: breaks to red/brown on texture and edges; looks best on iron
clay body. Mix to consistency of heavy cream and apply heavily for
best color.
click here to see a photo of the glaze:
http://home.earthlink.net/~jessieadair/tests/
Cornwall Stone 41.00
Kentucky Ball Clay (OM 4) 10.00
EPK 5.00
Lithium Carbonate 5.00
Strontium Carbonate 12.50
Whiting 10.00
Flint 16.50
Totals: 100.00 %
Also add:
Copper Oxide 2.50
Tin Oxide 4.50
Bentonite 2.00
Unity Formula for Juicy Turquoise:
0.056 K2O 0.354 Al2O3 2.909 SiO2
0.080 Na2O 0.004 Fe2O3 0.007 TiO2
0.366 CaO 0.005 P2O5 8.2:1 Si:Al Ratio
0.006 MgO
0.218 Li2O
0.273 SrO
Percentage Analysis for Juicy Turquoise:
62.73 % SiO2
12.96 % Al2O3
1.89 % K2O
1.78 % Na2O
7.37 % CaO
0.09 % MgO
2.34 % Li2O
10.16 % SrO
0.23 % Fe2O3
0.25 % P2O5
0.20 % TiO2
Results of lab testing for lithium and copper: Lithium 0.32 mg/L and
copper 11.2 mg/L
The copper is higher than I hoped for (was hoping for 5 or below) so I
wouldn't use this glaze on surfaces that come in contact with food.
Thanks to helpful suggestions from John Hesselberth, I have a few
things I can change in order to try and get better results:
1) add some boron (about 0.3) to help with the melt;
2) increase silica to about 3.0 (now it's at about 2.8) to increase
stability; and
3) source lithium from spodumene (less soluble source of lithium) to
help avoid the possibility of shivering
I will try and retain the lovely turquoise color as I make my changes
to the recipe so I have my work cut out for me as that is a difficult
color to achieve. The process from formulating to testing is one that
takes some time (but well worth the time and effort) so it will be a
while before I have the new results in.
Regards,
Linda Pahl, Kew Gardens, New York
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
email: TheClosetPotter@earthlink.net
website: http://home.earthlink.net/~jessieadair/tests/
///////////////////////////////////////////////////////////////
________________________________________________________________________
______
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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