Llewellyn Kouba on sat 24 mar 01
I received on an order - 1# of Laguna Borate and 5# of Boraq to begin tests
for the substitutions of Gerstley Borate in a given glaze formula.
Can someone tell me the ratio for Laguna Borate when used as a sub?
I also do not know the ratio for boraq. I understand that the company is
developing a boraq 1 and a boraq 2, one for low fire and one for high fire.
The product as I received it from my supplier does not indicate a series 1
or 2 so am at a loss as to what the equivallent should be? I have phoned
the supplier and they also do not know or advise on any substitution ratio
and are trying to find out.
Any helps
Llewellyn Kouba
scott lykens on sun 25 mar 01
laguna borate. 1:1
its not gerstley borate however, its a sub for what gerstley borate did when
it was heated.
you may have been more dependant on gerstleys gelling and inconsistant
nature than you thought. this does not gell. so it wont create a hard
surface suitable for rough handling.
If your doing raku, you may find that like most low fire glazes, they dont
work all that well on high fire clays. so if your raku body is also a high
fire clay, well.
But, like any other glaze material, if you want it to be sticky and gelly
then add gum. if you feel like it doesnt suspend well. then add a
suspension agent that works in your chemistry. I suggest V-gum T.
its my favorite, and a little bit seems to make jam out of jelly.
Just a heads up before you start.
>From: Llewellyn Kouba
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>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Ratio for substitution on Laguna Borate & Boraq
>Date: Sat, 24 Mar 2001 10:46:19 -0700
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>I received on an order - 1# of Laguna Borate and 5# of Boraq to begin tests
>for the substitutions of Gerstley Borate in a given glaze formula.
>
>Can someone tell me the ratio for Laguna Borate when used as a sub?
>
>I also do not know the ratio for boraq. I understand that the company is
>developing a boraq 1 and a boraq 2, one for low fire and one for high fire.
>The product as I received it from my supplier does not indicate a series 1
>or 2 so am at a loss as to what the equivallent should be? I have phoned
>the supplier and they also do not know or advise on any substitution ratio
>and are trying to find out.
>
>Any helps
>Llewellyn Kouba
>
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Tony Hansen on tue 27 mar 01
> I also do not know the ratio for boraq. I understand that the company is
> developing a boraq 1 and a boraq 2, one for low fire and one for high fire.
> The product as I received it from my supplier does not indicate a series 1
> or 2 so am at a loss as to what the equivallent should be? I have phoned
> the supplier and they also do not know or advise on any substitution ratio
> and are trying to find out.
Boraq 1 is a 'base recipe' to service the ceramic community while we are
in the development process (we don't have all the answers yet). We have
compromised the base Boraq 1 chemistry to (it is a little lower in CaO,
MgO and SiO2 and higher in B2O3 than GB) make it melt more like
GB at lower temperatures.
Boraq 2 is recommended for cone six and above. Boraq 2 is not sold, you
have to make it by using this recipe:
84 Boraq 1
8 Dolomite
8 Whiting
Mix and shake this up in a bag (shake it very well to get a good mix) or
adjust your recipes as appropriate. For example, if a recipe contains 50%
GB, then use 50x0.84=42 of Boraq 1, 50x0.08=4 of dolomite and
50x0.08=4 for whiting. The Boraq 2 chemistry matches GB formula quite
closely (it is still a little short on silica which may be needed if the glaze
runs too much or crazes).
The web page at
http://www.digitalfire.com/gerstleyborate/order.shtml
provides Boraq dealers with the printed material that they are supposed
to send with each order of Boraq. However keep in mind that the web
site is always the most current source of information.
The Boraq page itself at
http://www.digitalfire.com/gerstleyborate/boraq.shtml
changes most often.
I've said it before and I'll say it again: No one-material-fits all substitute
is going to appear. The mineralogy-chemistry-physics triad is just too
complex and the model of GB that we have is just too sparse. A 'base recipe
with adjustments' is going to be the best approach for now until we learn
more.
====================================================
T o n y H a n s e n thansen@digitalfire.com
D I G I T A L F I R E C O R P O R A T I O N
http://digitalfire.com Calculation/Database Software for Ceramic Industry
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