Lea Holland on fri 19 may 06
Venerable Clayarters:
In anticipation of my first attempt at mixing glazes, I have been reading
Cooper's Potters Book of Glaze recipes, specifically about low-fire
earthenware glazes. Cooper identifies frits by functional descriptions such
as: "high alkaline frit," "calcium borate frit," "standard borax frit," etc.
My question is, what is the best Ferro frit match to these descriptions? I
will take a stab at it, and ask for correction and illumination...such as,
if a frit is high in alkaline, should it be lower in other ingredients? And
is it possible that one frit can work in more than one category?
High alkaline frit:
3110
K2 2.3
Na2O 15.3CaO 6.3
ZnO -
Al2O3 3.7
B203 2.6
SiO2 69.8
F -
-or-
3195
K2 -
Na2O 5.7
CaO 11.3
ZnO -
Al2O3 12.1
B203 22.4
SiO2 45.5
F -
-or-
3269
K2 8.1
Na2O 11.1
CaO 0.1
ZnO 1.0
Al2O3 13.2
B203 15.2
SiO2 49.71
F 1.6
Calcium borate frit:
3134
K2 -
Na2O 10.3
CaO 20.1
ZnO -
Al2O3 -
B203 23.1
SiO2 46.5
F -
-or-
3211
K2 -
Na2O -
CaO 42.09
ZnO -
Al2O3 -
B203 57.91
SiO2 -
F -
Standard borax frit:
3134
K2 -
Na2O 10.3
CaO 20.1
ZnO -
Al2O3 -
B203 23.1
SiO2 46.5
F -
-or-
3195
K2 -
Na2O 5.7
CaO 11.3
ZnO -
Al2O3 12.1
B203 22.4
SiO2 45.5
F -
Many thanks,
Lea in Memphis, with my nose stuck in books rather than making anything.
Dave Finkelnburg on fri 19 may 06
Lea,
Alkalis are sodium (Na), potassium (K), and lithium
(Li), as I think you have worked out.
In his fine book, "Oriental Glazes," Michael Bailey
lists a Standard Borax frit as 48.26% SiO2, 7.55%
Al2O3, 18.87% B2O3, 15.19% CaO, 1.33% K2O and 8.75%
Na2O. That's not so far from 4 parts by weight 3134
and 1 part kaolin, except it's short the K2O.
The 3211 is more of a calcium borate frit.
You can use one frit for all categories,or even no
frit, as long as chemically you can introduce all the
glaze chemicals in the right proportions. Bailey
states the ingredients by weight percent. Herman
Seger, a German, started a long tradition often
followed in industry of using a unity molecular
formula (UMF) to express the same information. IF you
study the data, both methods tell you exactly the same
information. Which you choose is a matter of
preference, not science. Recipes, on the other hand,
are not so easy to evaluate.
IF you can learn to convert a recipe to either
weight % or UMF you can use the ingredients you have
to achieve the same chemical composition for a glaze
as most recipes. Whether the glaze fires the same is
something else. Sometimes...though not so often I am
finding...different sources of the same chemicals
produce different results.
For those who have the opportunity to attend the
Southern Fried Ceramic Surfaces Symposium July 27-30
at Francis Marion University in Florence, SC, I'll be
talking about these things in much more detail during
two separate presentations. The Potters Council is
putting together a great workshop. I hope to see many
of you there!
Good glazing,
Dave Finkelnburg
--- Lea Holland wrote:
Cooper identifies frits by
> functional descriptions such
> as: "high alkaline frit," "calcium borate frit,"
> "standard borax frit," etc.
>
> My question is, what is the best Ferro frit match to
> these descriptions?
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David Hewitt on sat 20 may 06
Lea,
For what it is worth I would pick the following:-
High alkaline frit - 3110
Calcium borate frit - 3134
Standard borate frit - 3134
Your problem is a very common one when taking other potters recipes in
that they often do not give precise details. Only by trying these in
your particular circumstances will you find out if it works for you..
David
In message , Lea Holland writes
>Venerable Clayarters:
>
>In anticipation of my first attempt at mixing glazes, I have been reading
>Cooper's Potters Book of Glaze recipes, specifically about low-fire
>earthenware glazes. Cooper identifies frits by functional descriptions such
>as: "high alkaline frit," "calcium borate frit," "standard borax frit," etc.
>
>My question is, what is the best Ferro frit match to these descriptions? I
>will take a stab at it, and ask for correction and illumination...such as,
>if a frit is high in alkaline, should it be lower in other ingredients? And
>is it possible that one frit can work in more than one category?
>
>
>High alkaline frit:
>
>3110
>K2 2.3
>Na2O 15.3CaO 6.3
>ZnO -
>Al2O3 3.7
>B203 2.6
>SiO2 69.8
>F -
>
>-or-
>
>3195
>K2 -
>Na2O 5.7
>CaO 11.3
>ZnO -
>Al2O3 12.1
>B203 22.4
>SiO2 45.5
>F -
>
>-or-
>
>3269
>K2 8.1
>Na2O 11.1
>CaO 0.1
>ZnO 1.0
>Al2O3 13.2
>B203 15.2
>SiO2 49.71
>F 1.6
>
>Calcium borate frit:
>
>3134
>K2 -
>Na2O 10.3
>CaO 20.1
>ZnO -
>Al2O3 -
>B203 23.1
>SiO2 46.5
>F -
>
>-or-
>
>3211
>K2 -
>Na2O -
>CaO 42.09
>ZnO -
>Al2O3 -
>B203 57.91
>SiO2 -
>F -
>
>
>Standard borax frit:
>
>3134
>K2 -
>Na2O 10.3
>CaO 20.1
>ZnO -
>Al2O3 -
>B203 23.1
>SiO2 46.5
>F -
>
>-or-
>
>3195
>K2 -
>Na2O 5.7
>CaO 11.3
>ZnO -
>Al2O3 12.1
>B203 22.4
>SiO2 45.5
>F -
>
>Many thanks,
>Lea in Memphis, with my nose stuck in books rather than making anything.
--
David Hewitt
Web:- http://www.dhpot.demon.co.uk
Lea Holland on sat 20 may 06
Thanks to you two for your help...I'll have to look
up your symposium!
Lea
For those who have the opportunity to attend the
Southern Fried Ceramic Surfaces Symposium July 27-30
at Francis Marion University in Florence, SC, I'll be
talking about these things in much more detail during
two separate presentations. The Potters Council is
putting together a great workshop. I hope to see many
of you there!
Good glazing,
Dave Finkelnburg
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