Charles G Hughes on sat 8 apr 00
This posting includes the ideas given to me so far.
When people use "Mr." in front of my name, I recognize it as my whuppin'
name... OK, so allow me to publicly clarify my posting. I like the idea of a
GB substitute, it will be wonderful if it works and is cost and time
effective. The "wild concoction" I referred to seems to be a great basis for
a substitute, however it seems there must be another way to achieve
aesthetically pleasing results without Gerstley Borate. I believe Raku,
(correct me if I am wrong, and I know someone will), started with primarily
lead glazes in the Western Hemisphere, then there seemed to be a shift to
Colemanite and Gerstley Borate. Now that Gerstley Borate is no longer widely
available (I understand there is some to be had in Dallas) I suspect there
will be another evolution in glaze recipes that will take us to another
standard. The question is what? Potters everywhere got over the loss of lead
as a useful food glaze material, they got over Colemanite, they got over
Albany slip, and now Gerstley Borate is gone. We are still firing to the
same temperatures and a variety of glaze materials will yield a good melt at
that temperature. The range of acceptable results is going to vary from
potter to potter, some will have a difficult time letting go of what has
become a standard in their work, and others will experiment and perhaps we
will come up with something new and potentially as exciting as the
wonderful lustres achieved with the 80/20 mix. Here is what I know about the
Gerstley Borate and Raku situation:
I have recently been in touch with Laguna Clays, and they assure me they
have been researching a substitute with promising results so far.
Tom Buck suggested his 2 potential substitutes, which are posted at
http://www.digitalfire.com/education/material/syntheticgerstleyborate.htm
Tom, I thank you and if all else fails, I'll be mixing up your substitute
and blessing you for your abilities to construct such things. I simply don't
have the knowledge to do what you do. I am ever thankful that you share your
information and as I mentioned in my personal note of explanation to you,
you have always given me goodness and I did not mean to offend.
>From Steve Branfmans Raku FAQ: "R.6. What is a raku glaze?
Similar to the question of raku clays is the answer to this question. Any
glaze
that you can successfully raku fire is a raku glaze. The most important
factors
in identifying raku glazes is the temperature at which they mature, how you
plan on using them, and what kind of effects you are looking for. You must
also
keep in mind that if you are using a variety of glazes on the same pot or in
the same kiln load, unless you know that they all mature to your
satisfaction
at around the same temperature, you will be faced with varying degrees of
maturity. However, just because a glaze is formulated to fire at a
temperature
higher than your usual range doesn't mean that you should eliminate that
glaze
from your pallet. Experiment with your glazes to achieve a variety of
surface
effects from dry textures to surfaces with a high gloss. Don't limit
yourself
to homemade or personal glazes either. Try low fire commercial glazes for
some
unusual results."
>From Khaimraj Seepersad:
"you can use a frit , or an enamel frit for Raku glazes .
The idea is a clear glass at 012 to 05 . Try for 08 to
06 - Frit 3124 Ferro plus 5 to 10 % EPK .
Check Thompson Enamels - 1 606 291 3800 for a
High Acid Resistant - Titanium White Enamel , or
Matte - there are quite a few .
Also the Hard Fusing Clear temp - 1400 to 1500
deg . f
Will need some EPK to go higher - test .
Or 3134 Ferro - 34.4 % - sub - Hommel 14
3269 Ferro - 56.6 - sub - Pemco 25
EPK - 9.0
temperature - cone 015"
Someone also suggested I contact Steve Mills, who is a Raku man in England,
where they don't commonly use Gerstley Borate, but I haven't yet.. perhaps
he'll see this post and chime in with his usual batch of good advice. His
directions helped us build our Raku kiln and he provided us with wonderful
Sheffield Steel trimming tools. Steve, if you are out there, can you add
anything to the discussion?
And that is all I know folks, I guess I'll try to stay away from volatile
phrases like "wild concoction" in the future
Charles Hughes
----- Original Message -----
From: Tom Buck
To:
Sent: Thursday, April 06, 2000 2:59 PM
Subject: Re: Gerstley Borate and Raku
> ----------------------------Original message----------------------------
> Charles Hughes, it seems, doesn't like my "wild conconction" as a
> substitute for Gerstley Borate in Raku glazes. The basic problem is that
> the 80GB:20NSy is a widely used Raku base; it is cheap; it works well. If
> you wish to develop Raku glazes without GB, then using a Frit is the only
> way to get insoluble glaze slurries (Borax is soluble and will not sit
> well in a glaze on the shelf). The frits to employ with a redesigned
> recipe are 3124, 3134, 3278, 3195 (or their equals). But these frits will
> not emulate 80GB:20NSy because the SiO2 (and sometimes Al2O3) will be too
> high for a typical Raku firing.
> Mr Hughes can try glzcalc and see if his tests yield what he
> wants, a departure from 80:20. I fear he will be hard-pressed to get
> sastifying lustres.
>
> Tom Buck ) tel: 905-389-2339
> (westend Lake Ontario, province of Ontario, Canada).
> mailing address: 373 East 43rd Street,
> Hamilton ON L8T 3E1 Canada
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