Lili Krakowski on mon 28 aug 06
According to my Bailey catalog Amaco , Spectrum, and Laguna produce glazes
in dry as well as wet form. As there are a lot of glazes, I did not read
the whole thing, cannot tell you if each and every glaze listed can be had
dry. (And there may be other makers, but I only read the Bailey catalog.)
Definitely dry glazes are out there and you should talk to your dealer.
As to the blue glaze that turned out clear. Yes, add some blue. Either a
blue stain (follow directions for how much to add) and cobalt carbonate,
where I would start testing with 1% and work up to 2%.
For those who want to try this glaze but have no Gerstley Borate, I
recalculated and this is pretty close and IMO ok to test.
Whiting 10.5
Zinc Oxide 5.7
Talc 6.7
Kona F 4 Spar 30.4
Ferro Frit 3195 15.2
Flint 28.3
EPK Kaolin 3.1
I definitely would add 2% bentonite as well.
And this glaze, if clear without colorant, will be clear with it. It will
remain transparent albeit blue. For opacity add an opacifier.
Lili Krakowski
Be of good courage
Nancy Braches on mon 28 aug 06
Am I missing something on the Gerstley? I keep reading how people don't want to use it but the 3 glazes I love all have it in them....am I pending doom here?
Nancy
Hilltop Pottery
Lili Krakowski wrote:
According to my Bailey catalog Amaco , Spectrum, and Laguna produce glazes
in dry as well as wet form. As there are a lot of glazes, I did not read
the whole thing, cannot tell you if each and every glaze listed can be had
dry. (And there may be other makers, but I only read the Bailey catalog.)
Definitely dry glazes are out there and you should talk to your dealer.
As to the blue glaze that turned out clear. Yes, add some blue. Either a
blue stain (follow directions for how much to add) and cobalt carbonate,
where I would start testing with 1% and work up to 2%.
For those who want to try this glaze but have no Gerstley Borate, I
recalculated and this is pretty close and IMO ok to test.
Whiting 10.5
Zinc Oxide 5.7
Talc 6.7
Kona F 4 Spar 30.4
Ferro Frit 3195 15.2
Flint 28.3
EPK Kaolin 3.1
I definitely would add 2% bentonite as well.
And this glaze, if clear without colorant, will be clear with it. It will
remain transparent albeit blue. For opacity add an opacifier.
Lili Krakowski
Be of good courage
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John and Judy Hesselberth on tue 29 aug 06
On Aug 28, 2006, at 5:38 PM, Nancy Braches wrote:
> Am I missing something on the Gerstley? I keep reading how people
> don't want to use it but the 3 glazes I love all have it in
> them....am I pending doom here?
Hi Nancy,
Gerstley Borate has 2 potential problems. First its composition is
highly variable lot to lot and sometimes within a lot depending on
how well the lot was blended. That doesn't bother some people but if
it is a glaze you want to be able to reproduce that can be a big
problem. It can also be a problem if you are trying to duplicate
someone else's glaze who might have used a different lot.
Second, its future availability is unknown. It is my understanding
that the mine is closed. I believe Laguna has a large supply of it,
but when that is gone it is gone.
While GB has some desirable characteristics I am not aware of any C6
glazes that cannot be made without it by sourcing boron from a frit.
Maybe it is the case with raku or earthenware glazes--I have never
tried to duplicate some of those without GB.
When Ron Roy and I were developing the glazes for MC6Gs common wisdom
was that a good C6 chrome/tin red could not be made without GB. We
found that not to be the case although it did take several tries.
What we found to work was to replace GB and any kaolin in the
original recipe with a frit and a ball clay. This needs to be done by
matching--or closely matching--the Seger unity formulas between the
GB version and the frit version.
So for some of us the question of whether or not to use GB is just on
of 'why bother' when there are more reliable ways to get the same
result.
Regards,
John
Janine Roubik on tue 29 aug 06
People are straying from Gerstley Borate because the mine is going to shut down again - don't know exactly when, but at some point. I think it already shut down once, and they temporarily reopened it. All the GB replacements out there don't do quite the same things, and it there were/are so many variations in real Gerstley that it was kinda wacky anyhow. Unfortunately, there are tons and tons of glaze recepies that have GB in them. I've had to deal with that also. You could stockpile it, but then what happens if/when you run out?
Good luck! Let us know how things turn out.
Janine
Nancy Braches wrote:
Am I missing something on the Gerstley? I keep reading how people don't want to use it but the 3 glazes I love all have it in them....am I pending doom here?
Nancy
Hilltop Pottery
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Everyone is raving about the all-new Yahoo! Mail.
Richard White on wed 30 aug 06
There is an interesting article on the Ceramics Monthly website -
http://www.ceramicsmonthly.org/mustreads/substitutions.asp
that examines several alternatives to gerstley (or ghastly, some would
say...) borate in the infamous floating blue glaze. I couldn't determine
the date of the article, but it does mention the indeterminate status of
the mine as a consideration for availability, as well as the variable
nature of the original brand product.
as is especially true with glazes, your mileage may vary.
dw
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