That could be a nasty surprise (mixing up 5 gallons of glaze to then have to
throw it out or live with yucky results - how do you throw out 5 gallons of
glaze?)! Thank you. I suppose I will have to do some more thorough
analysis. Luckily I have read "Mastering Cone 6 Glazes" and already have
enough science background to know that CuO2 does not really equal CuO (same
weight will give different amounts of Copper molecules). I will be basing
my glazes on MC6G but their recipes are such, that what Silica, Neph, etc.
to use is not given and I did not have a clue what the source of Silica
would be (since most people are dependent on what their supplier has that
makes sense and it also makes clearer why the glazes have to be adjusted for
local use). When I used to make up glazes the supplies were there for me
and I never had to think about what they were or what to order..... Thanks
to all the postings I have now learned why milling matters and what the
trade offs are, that raw material sold under the same main name but from
different makers may have different chemical compositions, and that Flint
and Quartz are the material to buy for silica.... (though that one still
confuses me some), etc. I really do appreciate all the response.


"Steve Mills" wrote in message
news
To add a little to June's excellent advice. When you have settled on the
core selection of glazes that you like be as consistent as you can over
the materials you use, don't go for different stuff because it is
cheaper or your glazes could change for the worse.

Steve
Bath
UK


In article , ShantiP1
writes
I tend you use ceramic grade rutile which is darker than light rutile and
use
that unless light is specified.
As far as the whiting goes, aske your supplier what the difference is. I
know
with some wollastonites for instance, there is a bit of iron, so you
might want
to find whichever whiting or wollastonite is purer.
Although Custer and G200 can usually be used interchangeable, Custer has
a bit
more silica which can help prevent crazing if your recipe is on the
border as
far of expansion is concerned.
If you know how to reformulate a recipe, with or without software, it's
easy
enough to reformulate it for a different spar; but in most cases, either
one
would have a good chance of working.
The frits aren't interchangeable really, because although thy all have
boron,
the other ingredients vary. 3195 has more alumina in it for instance and
I use
that if I want a high alumina recipe and don't want too much clay in the
recipe. You get a bit more boron for the money in 3195 which is why I
often use
it, but I make sure it fits in on a molecular level with my recipe.

If you're working at cone 6 I would not advise getting your list of
materials
too small.

You can do without wollastonite and reformulate the recipe for silica and
whiting which is what wollastonite is composed of; but you'll have to
back
engineer the recipe.

For cone 6, minimum materials list, I would advise

Frit 3134
Neph sy
F4 soda spar
Custer
epk
OM4 ball clay
whiting
talc
dolomite
silica - 200 mesh
spodumene
zinc oxide
bentonite
Zircopax or Superpax
Tin Oxide
and your basic coloring oxides

With these ingredients you can formulate alkaline glazes, calcium or
alumina
matts, etc. These are also the ingredients you would most commonly find
in cone
6 recipes.

If you want to extend the list, you can also get some of these to play
around
with:
wollastnite

barium carbonate
strontium carbonate
Lithium carbonate
Gillespie Borate or Boraq (Gerstley substitutes)
Volcanic ash
Frit 3124
Frit 3195

Regards,
June
http://www.angelfire.com/art2/shambhalapottery/




--
Steve Mills
Bath
UK