Steve Slatin on thu 2 mar 06
Paul --
GB is a likely source of the change --
there are big swings in the content of
GB.
If you are looking for a substitute
for GB, I'd recommend checking the
Ceramics Monthly article J. Zamek
wrote on the subject, on line at
http://www.ceramicsmonthly.org/mustreads/substitutions.asp
It focuses on floating blue glazes,
but it has analyses of several of the
GB substitutes now available.
My own experience is that frit 3134
is a pretty good substitute if you
don't use too much of it in a glaze.
If it's a significant part of your
glaze it'll probably melt OK but not
give you a similar effect.
Just my 2 colones -- Steve Slatin
--- Paul B wrote:
> i have heard that the amount of boron in
> gerstley borate can vary quite a
> bit and affect the color in copper red glazes.
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Paul B on thu 2 mar 06
i have heard that the amount of boron in gerstley borate can vary quite a
bit and affect the color in copper red glazes. Somewhere along the way the
copper red glazei use, which is Pete's red, started shifting more and more
toward strawberry, purple and even bluish while the firing schedule and
glaze application remained more or less the same. I found a few plates i
made about 2-3 years ago that i did not even know i still had and compared
them to some pots from recent firings and it looks like a totally different
glaze formula. I have notes on every firing i have done and gone through
them and found very little variation in terms of what temp to do body
reduction, length of firing, etc. The only other factor that could have
some influence is that i used to work with a commerical stoneware body that
had at least some redart in it, as evidenced by the light orange color the
pots had as they came out of the bisque, and i was thinking maybe the iron
had some influence, but i doubt that explains the whole thing.
So i am wondering if anyone has ever tried to reformulate this glaze using
frit 3134 in place of the gerstley - and if so, could you share the recipe?
I just don't have any glaze calc software at the moment - i hope to at some
point but at the moment web building software has me challenged enough.
thanks for any help,
Paul
Ingeborg Foco on fri 3 mar 06
Paul said: I have heard that the amount of boron in gerstley borate can
vary quite a
> bit and affect the color in copper red glazes. Somewhere along the way the
> copper red glazei use, which is Pete's red, started shifting more and more
> toward strawberry, purple and even bluish while the firing schedule and
> glaze application remained more or less the same.
Paul,
I use Pete's red with 3134. Ron Roy formulated it for me some time years
ago to eliminate crazing. Lately I am experiencing the reds to be deeper
in color and I just finished an architectural piece that came out partially
blue.
I am also finding that it wants to spit, jump or boil off the vertical
surface onto the kiln shelf making a real mess. It is one strong glaze to
chisel off the shelves.
The recipe is at the studio; I'll bring it home this evening.
Ingeborg
the Potter's Workshop & Gallery
P.O. Box 510
3058 Stringfellow Road
St. James City, Florida 33956
239-283-2775
>
Ingeborg Foco on fri 3 mar 06
Paul,
Pete's Red #204 A (my number) Revised by Ron Roy in 2001
G200 28.00
Frit 3134 23.00
Whiting 9.00
EPK 18.00
Silica 22.00
Add:
Copper Carb 0.25
Tin 3.00
I fire to ^10.
^10 will be either flat or bent at 9 o'clock and everything in between.
Depends where in the kiln they are set.
I have been told that red is easier to achieve if you fire to 9 91/2 but
that doesn't work
for me and the rest of my glazes. I use an iron bearing stoneware body
"Phoenix" from Highwater Clay.
Hope this helps.
Ingeborg
the Potter's Workshop & Gallery
P.O. Box 510
3058 Stringfellow Road
St. James City, Florida 33956
239-283-2775
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