search  current discussion  categories  glazes - misc 

oxides in formulas

updated mon 23 may 05

 

Overall's on sun 22 may 05


if there are a few glazes I particularly like the visual and textural finishes of, but want to leave out the coloring oxides or formulate for different colors, will it affect the final outcome if the firing is the same?

John Hesselberth on sun 22 may 05


On May 22, 2005, at 2:42 PM, Overall's wrote:

> if there are a few glazes I particularly like the visual and textural
> finishes of, but want to leave out the coloring oxides or formulate
> for different colors, will it affect the final outcome if the firing
> is the same?

Yes, often it will. Some of the coloring oxides are also effective
fluxes; others less so. Like most things in pottery, it depends.

Regards,

John

P.S. Sorry, but I didn't know how to address you. Please sign you posts
so we will know how you like to be addressed. While I might guess that
Overall is your last name, I didn't know if that is what you like to be
called.

John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com

Dean Poole on sun 22 may 05


Some colorants are active fluxes and their omission might change the surface=

of the glaze. Likewise some oxides don=92t make pretty colors inside certain=

glaze chemistry. Sorry no easy answers on this you just have to test

Steve Slatin on sun 22 may 05


You get a very firm "perhaps" for this question.

It depends very much on the glaze, firing, and on the
oxide involved. Some oxides have especially powerful
effects other than color. Others, not so much. If
you're talking about removing 1% iron oxide from a
cone 6 oxidation glaze, I'd expect no effect other
than color. I have one glaze, though, that crazes
without colorants but not with TiO2 as a colorant.
And Cobalt at about 4% will make some very normal
uncolored glazes quite runny.

It'd be great if there were a list of oxides and
effects, but given the different ways we fire,
different types of glazes, temps, cooling schedules,
etc. you're probably going to have to test each glaze
without colorants just to see how it reacts. One
thing you can do is just make a really tiny test
batch, 200g or so, and try it on a test tile or a bowl
you don't care about. If it's really terrible you can
write it off, if it's good, you can test it on each of
your clay bodies and that 200g will be gone before you
know it.

Best wishes, and please let us know your results --
Steve Slatin


--- Overall's wrote:
> if there are a few glazes I particularly like the
> visual and textural finishes of, but want to leave
> out the coloring oxides or formulate for different
> colors, will it affect the final outcome if the
> firing is the same?
>


Steve Slatin --

Some men will do here for diamonds what some men will do here for gold

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com