Gregory D. Lamont on fri 10 jan 97
Dear Clayarters,
I have a recipe for a ^6 oxidation glaze called "Floating Red" containing
the following:
Gerstley Borate 55
Talc 15
Flint 30
----
100
add: RIO 15
This recipe has no source of alumina, and the Zakin analysis says it "...
does not match the parameters of a glaze because it is too low or too high
in silica, alumina or flux." Yet, I have a pot that was supposedly glazed
with this glaze that is a beautiful, dark red semi-matte surface with
beautiful mottling. Can one of you "glaze gurus" tell me what's happening here?
Thanks in advance,
Greg
Ron Roy on sun 12 jan 97
>----------------------------Original message----------------------------
>Dear Clayarters,
>
>I have a recipe for a ^6 oxidation glaze called "Floating Red" containing
>the following:
>
>Gerstley Borate 55
>Talc 15
>Flint 30
> ----
> 100
>add: RIO 15
>
>This recipe has no source of alumina, and the Zakin analysis says it "...
>does not match the parameters of a glaze because it is too low or too high
>in silica, alumina or flux." Yet, I have a pot that was supposedly glazed
>with this glaze that is a beautiful, dark red semi-matte surface with
>beautiful mottling. Can one of you "glaze gurus" tell me what's happening
>here?
>
>Thanks in advance,
>
>Greg
Hi Greg
Well I checked it and it certainly is not a "durable glaze" - which I think
is what you meant. Red lead dusted on a pot and fired could be called a
glaze but it would not be durable. There is a small amount of alumina
supplied with Gerstley Borate by the way.
Yes the glaze is way over in fluxes and way under in Alumina and low in
silica. Why does it stay on the pot? It's getting some alumina and silica
from the clay and it does not have much flux that promotes running. I still
find it hard to believe this glaze would not run. Perhaps if it was applied
thinly ... Anyone who wants to try this glaze - beware - protect your
shelves. It will not be suitable for food.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
PJLewing@aol.com on sun 12 jan 97
Greg,
You're right, this glaze has almost no alumina, and what little it has, it's
getting from the GB. And Zakin is correct that this glaze is way outside the
limit formulas for a stable glaze. You've probably also noticed that this
glaze runs downhill faster than a pig on roller skates. It's also true that
many of the coolest and most unusual glazes have values outside the limit
formulas. But, like this one, they also have problems. You just have to
decide if they're worth the hassles for what you're doing.
Paul Lewing, Seattle
http://digitalfire.com/magic/lewing.htm
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