lili krakowski on mon 18 jan 10
We all take enormous pride in the glazes we develop. And should. =3D
Creating a glaze is making something new to us, just as creating a new =3D
dish is. We can delight in our skill and achievements.
Fine.
The other day, I replaced artichoke hearts by heart of palm in a chicken =
=3D
recipe.(Because I know the characteristics they share) Turned out =3D
yummy. By the same token one can replace whiting and flint by =3D
Wollastonite, or GB by a frit...etc. Not earthshaking but useful, and =3D
often a "lifesaver".
Glazes, like dishes, belong in FAMILIES.. Glazes have as many relatives =3D
as stew!
The Elisabeth glaze that Ron, and then I, revised is one of gadzillion =3D
or more glazes in the calcium borate family.
Maurland original
ALL calculations by GlazeMasterT
.111 Na2O
.003 K2O
.002 MgO
.884 CaO
.422 Al2O3
.87 B2O3
3.956 SiO2
Ron revised it to this:
.174 Na2O
.099 K2O
.153 MgO
.573 CaO
1.000 Total
.315 Al2O3
.713 B2O3
2.908 SiO2
69.6 Exp
And because I hate GB as much as, in its day, I hated Colemanite, I =3D
revised it to by using Frit 3195.
.206 Na2O
.002 K2O
.028 MgO
.764 CaO
.289 Al2O3
.645 B2O3
2.876 SiO2
How different are these glazes in practice? I would expect not much. =3D
But wait a minute, didn't I speak of families?
Here is Lana Wilson's "kate younger" (gotten off ClayArt)
.245 Na2O
.001 K2O
.021 MgO
.733 CaO
.392 Al2O3
.82 B2O3
3.118 SiO2
And how about=3D20
Coleman (Gotten off ClayArt)(test 1)
=3D20
.347 Na2O
.009 K2O
.02 MgO
.625 CaO
.225 Al2O3
.669 B2O3
.
2.871 SiO2
Or my BB Clear:
.282 Na2O
.024 K2O
.008 MgO
.686 CaO
1.000 Total
.36 Al2O3
.535 B2O3
.004 Fe2O3
4.449 SiO2
which has never given me trouble, but is close to RonJohns too low COE =3D
line.
ALL of these belong to the calcium borate family, subclass soda, =3D
although Ron's revision has lower soda and more magnesium than the =3D
other guys.=3D20
This all is one reason glaze calculation matters. If you own a computer =
=3D
or have access to one, a calculation program is worthwhile--but pencil =
=3D
and paper will do just fine (That is how we coped the first 100 years or =
=3D
so, though some of us had slide rules, and later we all had calculators.
As I said with books: when you consider the high price of clay and the =3D
high cost of firing--whatever you invest in the glaze area to achieve =3D
good results is worth it.=3D20
You really need to get an understanding of what glaze materials DO. A =3D
lot of questions ClayArt gets can be answered in the privacy of one's =3D
home if one learns this stuff.
My favorite glazes are high magnesium glazes with a lot of tin and =3D
titanium...Ok. Anyone who feels like it now can tell me--on (Mel?) or =3D
off list what it is that I look for....why would I want glazes like =3D
that..and more: what do I look out for? (Think colorants)
Lili Krakowski
Be of good courage
David Hendley on tue 19 jan 10
Like Lili, Some of my favorite and most-used glazes, as well, are high
magnesium with titanium. Not tin so much.
Here's why I like them:
--Low coefficient of expansion from the magnesium. It is a similar
flux to calcium, but the expansion is much lower, helping to
control crazing.
--Nice surface feel, perfect for a semi-matt that doesn't feel
dry as some matt glazes do.
--Great visual texture from the titanium.
--Different color response than usual from colorants and stains,
especially cobalt, which can go to purple from the magnesium or
green from the titanium.
I usually use Texas talc as my source for magnesium because it
is very inexpensive and my glazes can always use more silica.
For the titanium, I use rutile or titanium dioxide. Rutile is much
cheaper, but sometimes I don't want the added iron.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
We all take enormous pride in the glazes we develop. And should. Creatin=
g
a glaze is making something new to us, just as creating a new dish is. We
can delight in our skill and achievements.
Fine.
The other day, I replaced artichoke hearts by heart of palm in a chicken
recipe.(Because I know the characteristics they share) Turned out yummy.
By the same token one can replace whiting and flint by Wollastonite, or GB
by a frit...etc. Not earthshaking but useful, and often a "lifesaver".
Glazes, like dishes, belong in FAMILIES.. Glazes have as many relatives as
stew!
The Elisabeth glaze that Ron, and then I, revised is one of gadzillion or
more glazes in the calcium borate family.
This all is one reason glaze calculation matters. If you own a computer or
have access to one, a calculation program is worthwhile--but pencil and
paper will do just fine (That is how we coped the first 100 years or so,
though some of us had slide rules, and later we all had calculators.
As I said with books: when you consider the high price of clay and the high
cost of firing--whatever you invest in the glaze area to achieve good
results is worth it.
You really need to get an understanding of what glaze materials DO. A lot
of questions ClayArt gets can be answered in the privacy of one's home if
one learns this stuff.
My favorite glazes are high magnesium glazes with a lot of tin and
titanium...Ok. Anyone who feels like it now can tell me--on (Mel?) or off
list what it is that I look for....why would I want glazes like that..and
more: what do I look out for? (Think colorants)
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