mardi 11 septembre 2012



Colemanite has been absent from the North American market
for many years. No substitute on a 1 for 1 basis has been found
so far. Other ways to make substitutions with materials available
in both Europe and North America are explained elsewhere:

http://colemanite.blogspot.ca/

In addition, I recently made substitutions using a software
(2.1 GlazeChem, Bob Wilt) on a glaze recipe that I love
(see above).
This approach allowed me to make all the materials of this
recipe interact to achieve a better fit.

Now let's see the results :

1 - White V.O. # 1 is the original recipe.
2 - White VO # 2 is the result of the substitution, on a 1 to 1 basis,
with Gerstley Borate.
3 - White VO # 3 is the result of the substituion, on a 1 to 1 basis,
with Ferro frit 3134.
4 - White # 4 VO is the result of the substitution by Gerstley Borate,
taking into account all the materials of the recipe.
5 - White VO # 5 is the result of the substitution by Ferro frit 3134,
taking into account all the materials of the recipe.

It is up to you to choose,


La Colemanite est absente du marché nord-amérivain depuis
de nombreuses années.
On ne lui a pas trouvé encore de substitut 1 pour 1.
D'autres façons de procéder à sa substitution sont expliquées
avec des matières disponibles autant en Europe qu'en Amérique
du Nord:

http://colemanite.blogspot.ca/

De plus, j'ai récemment procéder à des substitutions à l'aide
d'un logiciel (GlazeChem 2.1 de Bob Wilt),
sur la recette d'une glaçure que j'affectionne particulièrement.
(voir plus haut)
Cette approche m'a permis de faire inter-réagir tous les
matériaux de cette recette pour parvenir à un meilleur ajustement.

Maintenant allons voir les résultats des calculs :

1- White V.O. #1 est la recette originale.
2- White V.O. #2 est résultat de la substitution 1 pour 1
avec le Gerstley Borate.
3- White V.O. #3 est le résultat de la substituion 1 pour 1
avec la fritte Ferro 3134.
4- White V.O. #4 est le résultat de la substitution par le
Gerstley Borate, en tenant compte de tous les matériaux
de la recette.
5- White V.O #5 est le résultat de la substitution par la
fritte Ferro 3134, en tenant compte de tous les matériaux
de la recette.

À vous de choisir,













White VO #1

Nepheline syenite 51
Colemanite 6
Dolomite 6
Talc 15
EPK 4
Silica 18
Totql 100

Na2O 5.8% Al2O3 14.4% SiO2 62.4%
K2O 2.6% B2O3 3.2% P2O5 0.0%
MgO 6.2% TiO2 0.0%
CaO 5.2% Fe2O3 0.1%

Volatiles:
H2O 1.4%
CO2 3.0%
Other 1.5%

Loss On Ignition: 5.6%

Expansion: 72.7 x 10e-7 per degree C
Oxides causing abnormal expansion: B2O3

Na2O 0.25 Al2O3 0.38 SiO2 2.83
K2O 0.08 B2O3 0.13 P2O5 0.00
MgO 0.42 TiO2 0.00
CaO 0.25 Fe2O3 0.00

Alumina:Silica ratio is 1.00:7.36
Neutral:Acid ratio is 1.00:5.55
Alk:Neut:Acid ratio is 1.00:0.51:2.83

White V.O. #2

Nepheline syenite 51
Gerstley 6
Dolomite 6
Talc 15
EPK 4
Silica 18
Total 100

Na2O 6.1% Al2O3 14.5% SiO2 63.4%
K2O 2.6% B2O3 1.9% P2O5 0.0%
MgO 6.4% TiO2 0.0%
CaO 4.9% Fe2O3 0.1%

Volatiles:
CO2 3.0%
Other 3.3%

Loss On Ignition: 6.0%

Expansion: 73.7 x 10e-7 per degree C
Oxides causing abnormal expansion: B2O3

Na2O 0.26 Al2O3 0.38 SiO2 2.82
K2O 0.08 B2O3 0.07 P2O5 0.00
MgO 0.43 TiO2 0.00
CaO 0.23 Fe2O3 0.00

Alumina:Silica ratio is 1.00:7.40
Neutral:Acid ratio is 1.00:6.24
Alk:Neut:Acid ratio is 1.00:0.45:2.82

White V.O. #3

Nepheline syenite 51
Frit 3134 6
Dolomite 6
Talc 15
EPK 4
Silica 18
Total 100

Na2O 6.4% Al2O3 14.2% SiO2 64.5%
K2O 2.6% B2O3 1.4% P2O5 0.0%
MgO 6.1% TiO2 0.0%
CaO 4.7% Fe2O3 0.1%

Volatiles:
CO2 3.0%
Other 1.4%

Loss On Ignition: 4.2%

Expansion: 74.0 x 10e-7 per degree C
Oxides causing abnormal expansion: B2O3

Na2O 0.28 Al2O3 0.38 SiO2 2.94
K2O 0.08 B2O3 0.06 P2O5 0.00
MgO 0.41 TiO2 0.00
CaO 0.23 Fe2O3 0.00

Alumina:Silica ratio is 1.00:7.71
Neutral:Acid ratio is 1.00:6.71
Alk:Neut:Acid ratio is 1.00:0.44:2.94

White V.O. #4

Nepheline syenite 47
Gerstley 13
Dolomite 2
Talc 16
EPK 5
Silica 17
Total 100

Na2O 6.0% Al2O3 14.0% SiO2 61.8%
K2O 2.5% B2O3 4.0% P2O5 0.0%
MgO 6.1% TiO2 0.0%
CaO 5.3% Fe2O3 0.1%

Volatiles:
CO2 1.0%
Other 5.7%

Loss On Ignition: 6.3%

Expansion: 73.2 x 10e-7 per degree C
Oxides causing abnormal expansion: B2O3

Na2O 0.26 Al2O3 0.37 SiO2 2.77
K2O 0.07 B2O3 0.16 P2O5 0.00
MgO 0.41 TiO2 0.00
CaO 0.26 Fe2O3 0.00

Alumina:Silica ratio is 1.00:7.46
Neutral:Acid ratio is 1.00:5.25
Alk:Neut:Acid ratio is 1.00:0.53:2.78


White V.O. #5

Nepheline syenite 43
Frit 3134 13
Dolomite 5
Talc 16
EPK 8
Silica 15

Na2O 6.2% Al2O3 13.8% SiO2 62.3%
K2O 2.2% B2O3 3.1% P2O5 0.0%
MgO 6.2% TiO2 0.0%
CaO 5.9% Fe2O3 0.1%

Volatiles:
CO2 2.5%
Other 2.1%

Loss On Ignition: 4.4%

Expansion: 73.7 x 10e-7 per degree C
Oxides causing abnormal expansion: B2O3

Na2O 0.26 Al2O3 0.35 SiO2 2.71
K2O 0.06 B2O3 0.12 P2O5 0.00
MgO 0.40 TiO2 0.00
CaO 0.27 Fe2O3 0.00

Alumina:Silica ratio is 1.00:7.65
Neutral:Acid ratio is 1.00:5.75
Alk:Neut:Acid ratio is 1.00:0.47:2.71