Bruce Girrell on thu 13 jan 00
I understand that _chemically_ we can substitute frits for GB, but many raku
recipes call for an 80/20 GB/NS mix. But a good glaze not only has certain
chemical characteristics, it also has certain _mechanical_ characteristics -
settling, adhesion, susceptibility/resistance to flaking, surface character,
etc.
I have to believe that a glaze containing 80% frit is going to sink to the
bottom of your glaze bucket and harden like a rock in about 30 seconds. I
not sure whether it will coat better or worse than a GB recipe, or whether
it will tend to flake or not. I suspect it will have a nicer surface for
subsequent brush work or other decoration.
I tried replacing GB with frit a while back (because of the bubbling that GB
undergoes while firing) and, though I got a glaze that had OK opacity and
crackle, I was very unhappy with the handling characteristics of the glaze
and I abandoned it.
How do you others see this aspect of changing over to a frit replacement for
GB? How can we keep the glaze suspended? Frits aren't going to respond well
to our normal flocculants. Too much bentonite and the glaze is going to
crack and flake. What experiences have you folks had in replacing GB with
frits?
B.G.
Carolynn Palmer on fri 14 jan 00
I have a favorite glaze (used it for over 25 years!) that is almsot 50%
gerstley borate. This glaze's most wonderful properties are in the bucket
and the way it clings to the bisque. It has such a wide firing range. It is
so forgiving. Early last year I had some problems with the gerstley borate
and tried to sub frit 3134 for part of it and it lost all of its good
properties, gained no new good ones, and settled to the bottom of the bucket
like cement.
I really lament the loss of Gerstley Borate.
Carolynn Palmer, Somerset Center, Michigan
ababy sharon on sun 16 jan 00
A letter to B.G. about G.B.
Gerstley borate has some problems too. Actually even before the sad news, I
decided to use it less! The first reason , is the changing analysis: For me
or anyone else that try to convert materials through a software, and cannot
be sure of the analysis , or for you, about which G.B. you write the one
with the 50% B2O3 or the other with the 27%? Does the recipe you prepared
5 years ago works the same? What about the problem of getting soluble after
half a year?
anyway it is a good problem, food for our heads to find new solutions.
Ababi
----- Original Message -----
From: Bruce Girrell
To:
Sent: Friday, January 14, 2000 12:02
Subject: Substituting frits for Gerstley borate - it's not all that simple
> ----------------------------Original message----------------------------
> I understand that _chemically_ we can substitute frits for GB, but many
raku
> recipes call for an 80/20 GB/NS mix. But a good glaze not only has certain
> chemical characteristics, it also has certain _mechanical_
characteristics -
> settling, adhesion, susceptibility/resistance to flaking, surface
character,
> etc.
>
> I have to believe that a glaze containing 80% frit is going to sink to the
> bottom of your glaze bucket and harden like a rock in about 30 seconds. I
> not sure whether it will coat better or worse than a GB recipe, or whether
> it will tend to flake or not. I suspect it will have a nicer surface for
> subsequent brush work or other decoration.
>
> I tried replacing GB with frit a while back (because of the bubbling that
GB
> undergoes while firing) and, though I got a glaze that had OK opacity and
> crackle, I was very unhappy with the handling characteristics of the glaze
> and I abandoned it.
>
> How do you others see this aspect of changing over to a frit replacement
for
> GB? How can we keep the glaze suspended? Frits aren't going to respond
well
> to our normal flocculants. Too much bentonite and the glaze is going to
> crack and flake. What experiences have you folks had in replacing GB with
> frits?
>
> B.G.
>
Tony Hansen on wed 19 jan 00
We've got a very detailed page on the issues surrounding Gerstley
Borate substitution. It is at:
http://www.digitalfire.com/education/material/gerstley.htm
This page does not rattle off subs, but helps you understand what
GB, Cadycal and Frits are, that you have to attack the problem on a
case-by-case basis, and that the substitution effort provides a
great opportunity to fix other potential problems with the glaze.
====================================================
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
Ron Roy on sat 22 jan 00
I just got 5 glazes out of my kiln - one with GB and the other 4 without -
all the same glaze - you can't tell the difference.
I used Cadycal, Frit 3134, 3124 and Fusion frit 309 in different
combinations. I'll have them with me at Cermatech.
I feel confident now I can duplicate any glaze with GB and solve the
problems in the bucket at the same time.
I also feel I can make the glazes "unreliable" as well by introducing other
materials - which I don't think many will take me up on - especially if
they are trying to make a living selling pots.
A word of cauction about stocking up on GB - the latest analysis I have is
quite different from ealier versions - I still think it best to have no
more than 10% GB in glazes.
There is another problem in all this - Hamill & Gillespie no longer puts
batch numbers on their bags - the question now is - which analysis is the
right one for the material you have?
There really is no need to panic about the lack of GB - as someone else
pointed out - this will be a blessing in the long run.
RR
>I do think that GB has some qualities that cannot be duplicated by frits.
>After all a frit is a carefully measured ingredient produced by man,
>whereas mother nature cooked up the infinitely variable and wonderfully
>unpredictable Gerstley Borate.
>I also think that appealing, reliable glazes can be made without GB...but
>I'm just not going to give up having some of my favorite glazes simply
>because the mine is closing down.
>
>I'm off to order a truckload of GB.................when the supply runs out
>and the panic starts, this may not seem as nuts as it sounds...
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
David McDonald on mon 24 jan 00
Hi Ron,
Many thanks for your work in firing glazes using substitutes for
Gertsley Borate, and sharing the results with the rest of us. I'm looking
forward to trying them myself. There is one thing that I've been really
wondering about, which I haven't seen mentioned yet. At the cone ten
reduction temperatures many of us fire to, there are often patterns left
in the glazes, which are oil spot-like, hare's fur-like, deep and
beautifully textured, which are quite obviously the remnant effects of
the volitile boiling and bubbling stages the glazes go through on their
way to maturity. I have suspected for a long time, that it is materials
like Gertsley Borate, and it's unstable cousins, that contribute so
heartily to this bubbling and spewing during sintering and melting, and
flowing and interacting with adjacent, underlying & overlapping glazes
and their components. I believe it's important to find qualified
substitutes for these disappearing materials, which we have come to rely
on, but I'm hoping that in bringing in such processed and refined
materials as frits, that we don't lose too many of those wonderful
effects that have been around with us for so long. I'm sure curious about
your thoughts on this. Thanks again Ron, for your continual, and
enlightening contributions. David McDonald
claydog@juno.com
On Sat, 22 Jan 2000 16:33:40 EST Ron Roy writes:
> ----------------------------Original
> message----------------------------
> I just got 5 glazes out of my kiln - one with GB and the other 4
> without -
> all the same glaze - you can't tell the difference.
>
> I used Cadycal, Frit 3134, 3124 and Fusion frit 309 in different
> combinations. I'll have them with me at Cermatech.
>
> I feel confident now I can duplicate any glaze with GB and solve the
> problems in the bucket at the same time.
>
> I also feel I can make the glazes "unreliable" as well by
> introducing other
> materials - which I don't think many will take me up on - especially
> if
> they are trying to make a living selling pots.
>
> A word of cauction about stocking up on GB - the latest analysis I
> have is
> quite different from ealier versions - I still think it best to have
> no
> more than 10% GB in glazes.
>
> There is another problem in all this - Hamill & Gillespie no longer
> puts
> batch numbers on their bags - the question now is - which analysis
> is the
> right one for the material you have?
>
> There really is no need to panic about the lack of GB - as someone
> else
> pointed out - this will be a blessing in the long run.
>
> RR
>
>
> >I do think that GB has some qualities that cannot be duplicated by
> frits.
> >After all a frit is a carefully measured ingredient produced by
> man,
> >whereas mother nature cooked up the infinitely variable and
> wonderfully
> >unpredictable Gerstley Borate.
> >I also think that appealing, reliable glazes can be made without
> GB...but
> >I'm just not going to give up having some of my favorite glazes
> simply
> >because the mine is closing down.
> >
> >I'm off to order a truckload of GB.................when the supply
> runs out
> >and the panic starts, this may not seem as nuts as it sounds...
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough
> Ontario, Canada
> M1G 3N8
> Evenings 416-439-2621
> Fax 416-438-7849
________________________________________________________________
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Juno now offers FREE Internet Access!
Try it today - there's no risk! For your FREE software, visit:
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Ron Roy on tue 25 jan 00
Hi David,
I don't think it's the boron that is doing the boiling thing - more likely
other oxides like MgO - If you want to do some experiments I will be back
Feb 11th - send me a problem then.
RR
>----------------------------Original message----------------------------
>Hi Ron,
> Many thanks for your work in firing glazes using substitutes for
>Gertsley Borate, and sharing the results with the rest of us. I'm looking
>forward to trying them myself. There is one thing that I've been really
>wondering about, which I haven't seen mentioned yet. At the cone ten
>reduction temperatures many of us fire to, there are often patterns left
>in the glazes, which are oil spot-like, hare's fur-like, deep and
>beautifully textured, which are quite obviously the remnant effects of
>the volitile boiling and bubbling stages the glazes go through on their
>way to maturity. I have suspected for a long time, that it is materials
>like Gertsley Borate, and it's unstable cousins, that contribute so
>heartily to this bubbling and spewing during sintering and melting, and
>flowing and interacting with adjacent, underlying & overlapping glazes
>and their components. I believe it's important to find qualified
>substitutes for these disappearing materials, which we have come to rely
>on, but I'm hoping that in bringing in such processed and refined
>materials as frits, that we don't lose too many of those wonderful
>effects that have been around with us for so long. I'm sure curious about
>your thoughts on this. Thanks again Ron, for your continual, and
>enlightening contributions. David McDonald
> claydog@juno.com
>
>On Sat, 22 Jan 2000 16:33:40 EST Ron Roy writes:
>> ----------------------------Original
>> message----------------------------
>> I just got 5 glazes out of my kiln - one with GB and the other 4
>> without -
>> all the same glaze - you can't tell the difference.
>>
>> I used Cadycal, Frit 3134, 3124 and Fusion frit 309 in different
>> combinations. I'll have them with me at Cermatech.
>>
>> I feel confident now I can duplicate any glaze with GB and solve the
>> problems in the bucket at the same time.
>>
>> I also feel I can make the glazes "unreliable" as well by
>> introducing other
>> materials - which I don't think many will take me up on - especially
>> if
>> they are trying to make a living selling pots.
>>
>> A word of cauction about stocking up on GB - the latest analysis I
>> have is
>> quite different from ealier versions - I still think it best to have
>> no
>> more than 10% GB in glazes.
>>
>> There is another problem in all this - Hamill & Gillespie no longer
>> puts
>> batch numbers on their bags - the question now is - which analysis
>> is the
>> right one for the material you have?
>>
>> There really is no need to panic about the lack of GB - as someone
>> else
>> pointed out - this will be a blessing in the long run.
>>
>> RR
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
David Hewitt on tue 25 jan 00
David,
>From my experience of oil spot glazes they do not need boron. The effect
is due to iron saturation in a glaze which allows for the crystals to
form in oxidation. You can see examples on my web site.
Also, as a generality, I would have thought that you would not be using
GB in cone 10 glazes, the main purpose of boron being to assist in
formulating glazes to work at lower temperatures, say cone 6 and below.
David
In message , David McDonald writes
>----------------------------Original message----------------------------
>Hi Ron,
> Many thanks for your work in firing glazes using substitutes for
>Gertsley Borate, and sharing the results with the rest of us. I'm looking
>forward to trying them myself. There is one thing that I've been really
>wondering about, which I haven't seen mentioned yet. At the cone ten
>reduction temperatures many of us fire to, there are often patterns left
>in the glazes, which are oil spot-like, hare's fur-like, deep and
>beautifully textured, which are quite obviously the remnant effects of
>the volitile boiling and bubbling stages the glazes go through on their
>way to maturity. I have suspected for a long time, that it is materials
>like Gertsley Borate, and it's unstable cousins, that contribute so
>heartily to this bubbling and spewing during sintering and melting, and
>flowing and interacting with adjacent, underlying & overlapping glazes
>and their components. I believe it's important to find qualified
>substitutes for these disappearing materials, which we have come to rely
>on, but I'm hoping that in bringing in such processed and refined
>materials as frits, that we don't lose too many of those wonderful
>effects that have been around with us for so long. I'm sure curious about
>your thoughts on this. Thanks again Ron, for your continual, and
>enlightening contributions. David McDonald
> claydog@juno.com
>
>On Sat, 22 Jan 2000 16:33:40 EST Ron Roy writes:
>> ----------------------------Original
>> message----------------------------
>> I just got 5 glazes out of my kiln - one with GB and the other 4
>> without -
>> all the same glaze - you can't tell the difference.
>>
>> I used Cadycal, Frit 3134, 3124 and Fusion frit 309 in different
>> combinations. I'll have them with me at Cermatech.
>>
>> I feel confident now I can duplicate any glaze with GB and solve the
>> problems in the bucket at the same time.
>>
>> I also feel I can make the glazes "unreliable" as well by
>> introducing other
>> materials - which I don't think many will take me up on - especially
>> if
>> they are trying to make a living selling pots.
>>
>> A word of cauction about stocking up on GB - the latest analysis I
>> have is
>> quite different from ealier versions - I still think it best to have
>> no
>> more than 10% GB in glazes.
>>
>> There is another problem in all this - Hamill & Gillespie no longer
>> puts
>> batch numbers on their bags - the question now is - which analysis
>> is the
>> right one for the material you have?
>>
>> There really is no need to panic about the lack of GB - as someone
>> else
>> pointed out - this will be a blessing in the long run.
>>
>> RR
>>
>>
>> >I do think that GB has some qualities that cannot be duplicated by
>> frits.
>> >After all a frit is a carefully measured ingredient produced by
>> man,
>> >whereas mother nature cooked up the infinitely variable and
>> wonderfully
>> >unpredictable Gerstley Borate.
>> >I also think that appealing, reliable glazes can be made without
>> GB...but
>> >I'm just not going to give up having some of my favorite glazes
>> simply
>> >because the mine is closing down.
>> >
>> >I'm off to order a truckload of GB.................when the supply
>> runs out
>> >and the panic starts, this may not seem as nuts as it sounds...
>>
>> Ron Roy
>> 93 Pegasus Trail
>> Scarborough
>> Ontario, Canada
>> M1G 3N8
>> Evenings 416-439-2621
>> Fax 416-438-7849
>
>________________________________________________________________
>YOU'RE PAYING TOO MUCH FOR THE INTERNET!
>Juno now offers FREE Internet Access!
>Try it today - there's no risk! For your FREE software, visit:
>http://dl.www.juno.com/get/tagj.
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
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