Mary/Adams on thu 25 aug 05
Am finding beautiful recipes for Cone 5-6 glazes (and Cone 10 as well) and
they call for Gerstley Borate. Is it no longer available? What is a good
substitute? Dolomite?
m
Steve Slatin on thu 25 aug 05
Mary --
Ceramics Monthly has an on-line article on the subject
of GB substitutes at --
www.ceramicsmonthly.org/mustreads/substitutions.asp
(get it all into the browser window to make the link
work). This will give you all the information you
need to pick a substitute if you want to -- there is
still some GB for sale, but some users say that it
differs from the old stuff. (Old users sometimes
called the old stuff "Ghastley Borate" because each
batch seemed to differ a bit.)
Gerstley Borate is not a mineral but an aggregate of
Colemanite (Hydrated Calcium Borate Hydroxide),
Ulexite (so-called 'television stone', sodium calcium
borate), some hectorite (lithium magnesium sodium
montmorillonite; a cousin of bentonite), a bit of
limestone and what have you.
Dolomite is a mineral, calcium magnesium carbonate;
the crystals are pink. It really has no chance of
being a reliable substitute for GB -- you may bit a
recipe where it works, but it'll be a complete
accident; the boron in GB lowers the melting temp and
acts as a glass former, neither of which the dolomite
will do; the quantity of calcium in the GB is much
lower so the glaze, if it matures without the boron
will be much more matte, etc.
If your recipe calls for small amounts of GB, frit
3134 may function as a substitute. I've had good luck
with it in recipes where no GB-specific results (like
surface-level turbulence) are required.
Best wishes -- Steve Slatin
--- Mary/Adams wrote:
> Am finding beautiful recipes for Cone 5-6 glazes
> (and Cone 10 as well) and
> they call for Gerstley Borate. Is it no longer
> available? What is a good
> substitute? Dolomite?
>
Steve Slatin --
Drove downtown in the rain
9:30 on a Tuesday night
Just to check out the
Late night record shop
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David Gallagher on fri 26 aug 05
Axner still has some (or found some more)
http://pottery-books.com/axner/supplies/materials.php
there is also a sub they push
Boraq (GB substitute) (dont know anything about it)
Mary/Adams wrote:
Am finding beautiful recipes for Cone 5-6 glazes (and Cone 10 as well) and
they call for Gerstley Borate. Is it no longer available? What is a good
substitute? Dolomite?
m
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Snail Scott on fri 26 aug 05
At 01:28 PM 8/25/2005 -0700, you wrote:
>Am finding beautiful recipes for Cone 5-6 glazes (and Cone 10 as well) and
>they call for Gerstley Borate. Is it no longer available?
It will eventually run out, though there's still
limited availability. Current Gerstley supplies are
different enough from what it was 20 years ago that
the recipes will probably come out looking different
even without a substitution, so instead of getting
attached to a dwindling material, start by using
other materials from the outset.
Many 'Gerstley Borate Substitutes' are manufactured
by various companies, under names like 'Laguna Borate',
'Gillespie Borate', 'Akiko Borate', 'Boraq', and a few
others. Frit 3134 will often serve the purpose, too.
3134 is quite a bit different from these others, but
it's worth a try. It's the easy fix, IF it works for
your recipes.
-Snail
Neal on fri 26 aug 05
> Am finding beautiful recipes for Cone 5-6 glazes
> (and Cone 10 as well) and they call for Gerstley
> Borate. Is it no longer available?
Mary: I just started mixing my own glazes a year
ago. I started by going through a few years' worth
of Ceramics Monthly, searching on the Internet for
cone 6 glazes, including in the Clayart archives,
and in various books. I have lots still to test.
After reading about the possibility of GB not
being available, I decided to test glazes that
did not contain it in a large percentage (<15%).
I planned to buy one of GB the substitutes. The
owner of the clay supply company asked me if I
wanted the real thing since she had it available.
I bought the real gerstley borate. So far, in my
testing of glazes, I have used very little. None
of the small test batches I have made with GB have
looked good enough to want to make in quantity.
Neal O'Briant
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Ron Roy on fri 26 aug 05
The closest I have seen is Gillespie Borate - from Hamill and Gillespie
(sp) - most glazes can have the GB substituted by frit as well.
Web: http://www.hamgil.com
RR
>Am finding beautiful recipes for Cone 5-6 glazes (and Cone 10 as well) and
>they call for Gerstley Borate. Is it no longer available? What is a good
>substitute? Dolomite?
>
>m
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Wagoner, Charles on fri 26 aug 05
They have a lot of the real thing for sale at this address. I believe he
has two full skids and would be inclined to sell it at price breaks for
larger orders.
Indianapolis Ceramic Company
1034 E. New York St, Indianapolis, Indiana 46202
(317) 955-8444 fax:(317) 955-8333
http://www.debmark.com/index.htm
Charles T. Wagoner
cwagoner@nvc.k12.in.us cwag@abcs.com
http://www.abcs.com/cwag
http://www.billiecreekvillage.org
Alisa Liskin Clausen on fri 26 aug 05
Dear Clayart
For the record:
When I started testing glaze recipes they were almost exclusively Northern
American recipes. Many contained Gerstely Borate, which is available in
abundance in Denmark. It is, however, not a widely used glaze material
here of the past. Perhaps gained some popularity by people who were
introduced to it by non Danes. As G.B. began to dwindle in the USA I
dropped using it in my glazes to move with the times. It is, however,
still quite available here.
In the beginning of my testing, I tested Colemanite as a sub. Found that
most recipes with 20% or less of G.B., could tolerate a gram for gram sub.
of Colemanite. In general, the glazes were muddier than the original
recipe using G.B. Colemanite is not a good sub. anyway, because of it's
limited availability in the states (I heard) and it varies widely from
mine to mine.
As time went on, and testing as well, I subbed my boron frit, gram for
gram for Gerstely Borate. We had discussions about this on Clayart.
PMI,May-June 2004,posted a recipe, Maria's Blue, with 24 G.B or Frit 3134.
In this particular set of tests, the G.B., Frit 3134 and Frit 623 gave
slightly different color response. All of the surface melts were the same.
I was surprised by seeing this reicpe suggestion in print, because I had
not received any favorable response to my subbing Boron Frit for G.B. when
I initially asked about this on Clayart. I asked again. We talked about
that this not a suitable sub.because from an analysis point of view, I was
not subbing, but making an entirely different glaze. However, for
duplicating the aesthetic look of the G.B. glaze, melt, color and surface,
it was a good sub. Choose your camp. As said at that time, I think I
would like to be knowledgeable enough to duplicate a glaze by analysis,
but I think it is all right to duplicate a glaze, by making a new glaze
that looks like the old glaze, using local materials.
I have tested all of the glaze recipes with G.B. along the way over 4
years, with a gram for gram sub. of Boron Frit (3134, Frit J, 623, and MOK
3,) for G.B., and the surfaces, color response and melt has been, superb.
Every big batch of glaze I make that calls for G.B., I use a Boron Frit
gram for gram as substitute with good results.
Regards from Alisa in Denmark
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