Bill Merrill on thu 2 oct 08
Before everyone becomes afraid to use Gertsley Borate and uses a Boron
frit as a substitute for Gertsley Borate, I would suggest you do tests
to see how the glaze is changed using a frit versus using Gertsley
Borate. Subbing one material for another can change the glaze to
something totally different visually and technically.
John Hesselberth on fri 3 oct 08
Hi Bill,
You are right particularly if people try 1 for 1 substitution. I have
found the best way to make this particular substitution is to match
the unity formula AND replace any EPK with ball clay. That was the
only way I was able to find a good frit-based chrome/tin pink after
many tries--thanks to a suggestion from Ron Roy at the height of my
frustration. I'm not saying it can't be done other ways, but this is
what worked best for me.
Regards,
John
On Oct 2, 2008, at 7:18 PM, Bill Merrill wrote:
> Before everyone becomes afraid to use Gertsley Borate and uses a Boron
> frit as a substitute for Gertsley Borate, I would suggest you do tests
> to see how the glaze is changed using a frit versus using Gertsley
> Borate. Subbing one material for another can change the glaze to
> something totally different visually and technically.
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Alisa Clausen on sat 4 oct 08
Hi John and others subbing Frit for G.B.
I have subbed both G.B. with Frit by mol. wt. and added other materials
needed to get the glaze to be similar in Seger. However, I have had very
good success with my glazes appearences and melt by subbing gram for gram.
Even though the glaze is a different glaze, it is a glaze I can use.
Always trial and error. But trials always.
Best regards, Alisa in Denmark
On Fri, Oct 3, 2008 at 8:31 PM, John Hesselberth wrote:
> Hi Bill,
>
> You are right particularly if people try 1 for 1 substitution. I have
> found the best way to make this particular substitution is to match
> the unity formula AND replace any EPK with ball clay. That was the
> only way I was able to find a good frit-based chrome/tin pink after
> many tries--thanks to a suggestion from Ron Roy at the height of my
> frustration. I'm not saying it can't be done other ways, but this is
> what worked best for me.
>
> Regards,
>
> John
>
>
>
> On Oct 2, 2008, at 7:18 PM, Bill Merrill wrote:
>
> Before everyone becomes afraid to use Gertsley Borate and uses a Boron
>> frit as a substitute for Gertsley Borate, I would suggest you do tests
>> to see how the glaze is changed using a frit versus using Gertsley
>> Borate. Subbing one material for another can change the glaze to
>> something totally different visually and technically.
>>
>
> John Hesselberth
> http://www.frogpondpottery.com
> http://www.masteringglazes.com
>
Ron Roy on sun 5 oct 08
Best to use a glaze calculator for this - I have had good results subbing
frits for GB but always do it getting the oxides as close as possible.
RR
>Before everyone becomes afraid to use Gertsley Borate and uses a Boron
>frit as a substitute for Gertsley Borate, I would suggest you do tests
>to see how the glaze is changed using a frit versus using Gertsley
>Borate. Subbing one material for another can change the glaze to
>something totally different visually and technically.
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
jonathan byler on mon 6 oct 08
I always use kaolin because I don't know any better. it always
seemed like the best source of alumina, but I never thought about
ball clay having it too. I'll have to give the ball clay a shot.
somehow I always thought of ball clay as an inferior clay to use in
glazes as opposed to EPK.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Oct 6, 2008, at 3:36 PM, John Hesselberth wrote:
> Hi Jon,
>
> Some of what follows is hypothesis--not proven fact.
>
> Ball clay is a better suspending agent for glazes than is EPK and you
> lose that advantage of GB when you replace it with a frit. But I think
> there are other trace components in GB that are also more likely to be
> in ball clay than in the more pure kaolin. I don't pretend to
> understand why this is important, but I know in the case of a chrome/
> tin pink it was the only way I could get the color development. In
> fact I was told by knowledgeable glaze experts a chrome/tin pink at
> cone 6 required GB and could not be made with a frit. It took a lot of
> tries and ball clay to prove them wrong. Now someone better than I may
> be able to develop one with EPK and a frit, but I failed over a
> several month period.
>
> So in summary, I surmise that ball clay replaces some of what you lose
> that is good about GB--and have you noticed that almost all GB-
> containing recipes have kaolin as the clay? Interesting. I wonder why.
>
> Regards,
>
> John
> On Oct 6, 2008, at 1:49 PM, jonathan byler wrote:
>
>> why would one sub ball clay for the EPK when doing this? what is the
>> advantage?
>>
>> thanks,
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>>
>>> Hi Bill,
>>>
>>> You are right particularly if people try 1 for 1 substitution. I
>>> have
>>> found the best way to make this particular substitution is to match
>>> the unity formula AND replace any EPK with ball clay. That was the
>>> only way I was able to find a good frit-based chrome/tin pink after
>>> many tries--thanks to a suggestion from Ron Roy at the height of my
>>> frustration. I'm not saying it can't be done other ways, but this is
>>> what worked best for me.
>>>
>>> Regards,
>>>
>>> John
>>>
>>>
>>>
>>> On Oct 2, 2008, at 7:18 PM, Bill Merrill wrote:
>>>
>>>> Before everyone becomes afraid to use Gertsley Borate and uses a
>>>> Boron
>>>> frit as a substitute for Gertsley Borate, I would suggest you do
>>>> tests
>>>> to see how the glaze is changed using a frit versus using Gertsley
>>>> Borate. Subbing one material for another can change the glaze to
>>>> something totally different visually and technically.
>>>
>>> John Hesselberth
>>> http://www.frogpondpottery.com
>>> http://www.masteringglazes.com
>
> John Hesselberth
> www.frogpondpottery.com
>
> "Man is a tool-using animal....without tools he is nothing, with tools
> he is all" .... Thomas Carlyle
jonathan byler on mon 6 oct 08
why would one sub ball clay for the EPK when doing this? what is the
advantage?
thanks,
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
> Hi Bill,
>
> You are right particularly if people try 1 for 1 substitution. I have
> found the best way to make this particular substitution is to match
> the unity formula AND replace any EPK with ball clay. That was the
> only way I was able to find a good frit-based chrome/tin pink after
> many tries--thanks to a suggestion from Ron Roy at the height of my
> frustration. I'm not saying it can't be done other ways, but this is
> what worked best for me.
>
> Regards,
>
> John
>
>
>
> On Oct 2, 2008, at 7:18 PM, Bill Merrill wrote:
>
>> Before everyone becomes afraid to use Gertsley Borate and uses a
>> Boron
>> frit as a substitute for Gertsley Borate, I would suggest you do
>> tests
>> to see how the glaze is changed using a frit versus using Gertsley
>> Borate. Subbing one material for another can change the glaze to
>> something totally different visually and technically.
>
> John Hesselberth
> http://www.frogpondpottery.com
> http://www.masteringglazes.com
John Hesselberth on mon 6 oct 08
Hi Jon,
Some of what follows is hypothesis--not proven fact.
Ball clay is a better suspending agent for glazes than is EPK and you
lose that advantage of GB when you replace it with a frit. But I think
there are other trace components in GB that are also more likely to be
in ball clay than in the more pure kaolin. I don't pretend to
understand why this is important, but I know in the case of a chrome/
tin pink it was the only way I could get the color development. In
fact I was told by knowledgeable glaze experts a chrome/tin pink at
cone 6 required GB and could not be made with a frit. It took a lot of
tries and ball clay to prove them wrong. Now someone better than I may
be able to develop one with EPK and a frit, but I failed over a
several month period.
So in summary, I surmise that ball clay replaces some of what you lose
that is good about GB--and have you noticed that almost all GB-
containing recipes have kaolin as the clay? Interesting. I wonder why.
Regards,
John
On Oct 6, 2008, at 1:49 PM, jonathan byler wrote:
> why would one sub ball clay for the EPK when doing this? what is the
> advantage?
>
> thanks,
> jon
>
>
> jon byler
> 3-D Building Coordinator
> Art Department
> Auburn University, AL 36849
>
> On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>
>> Hi Bill,
>>
>> You are right particularly if people try 1 for 1 substitution. I have
>> found the best way to make this particular substitution is to match
>> the unity formula AND replace any EPK with ball clay. That was the
>> only way I was able to find a good frit-based chrome/tin pink after
>> many tries--thanks to a suggestion from Ron Roy at the height of my
>> frustration. I'm not saying it can't be done other ways, but this is
>> what worked best for me.
>>
>> Regards,
>>
>> John
>>
>>
>>
>> On Oct 2, 2008, at 7:18 PM, Bill Merrill wrote:
>>
>>> Before everyone becomes afraid to use Gertsley Borate and uses a
>>> Boron
>>> frit as a substitute for Gertsley Borate, I would suggest you do
>>> tests
>>> to see how the glaze is changed using a frit versus using Gertsley
>>> Borate. Subbing one material for another can change the glaze to
>>> something totally different visually and technically.
>>
>> John Hesselberth
>> http://www.frogpondpottery.com
>> http://www.masteringglazes.com
John Hesselberth
www.frogpondpottery.com
"Man is a tool-using animal....without tools he is nothing, with tools
he is all" .... Thomas Carlyle
Ron Roy on fri 10 oct 08
Hi Jon,
GB has some shale in it - I assume there are some trace oxides amounts in
the shale that help whatever happens to form red crystals from tin and
chrome - if that is the case - ball clays would have more trace oxides than
kaolin would.
When I look at the analysis for EPK I see 0.30% TiO2 - for the ball Clays I see
1.20,1.50, .90,1.80,1.40 - in other words a lot more. In this case John
used OM#4 which has a typical analysis for TiO2 at 1.20% - 4 times the
amount of TiO2. TiO2 helps crystals start forming - gives them something to
start building on. Is it the same thing with crystals of sugar helping
fudge solidify?
I also see more TiO2 in Tile6, Helmer, and Pioneer kaolins - perhaps they
would have worked as well - especially Helmer with 1.13% TiO2?
I think - if kaolin is less than 10% of a glaze - there is a big advantage
to subbing ball clay - better suspension and a harder dry glaze surface -
way less powdering when pots are handled after glazing.
You would need 13.5 OM #4 to replace 10% EPK in a glaze (and lower silica
by 3.5 because ball clay has less alumina than EPK and more silica.
If suspension did not improve enough - adding 1 or 2% bentonite would most
likely do the trick - ball clay and bentonite work better together than
bentonite and kaolin.
Doing these kinds of materials substitution is best done using calculation
software by the way - or get someone who does know how to use it to do it
for you. It does work well and can solve many problems.
RR
>why would one sub ball clay for the EPK when doing this? what is the
>advantage?
>
>thanks,
>jon
>
>
>jon byler
>3-D Building Coordinator
>Art Department
>Auburn University, AL 36849
>
>On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>
>> Hi Bill,
>>
>> You are right particularly if people try 1 for 1 substitution. I have
>> found the best way to make this particular substitution is to match
>> the unity formula AND replace any EPK with ball clay. That was the
>> only way I was able to find a good frit-based chrome/tin pink after
>> many tries--thanks to a suggestion from Ron Roy at the height of my
>> frustration. I'm not saying it can't be done other ways, but this is
>> what worked best for me.
>>
>> Regards,
>>
>> John
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
jonathan byler on fri 10 oct 08
ron,
thanks for the explanation. When I do some more tests I will try
recalculating for the ball clay instead of using epk. I suppose one
could add a pinch of TiO2, but then you wouldn't have the added
benefits of the better suspension properties you mentioned.
-jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Oct 10, 2008, at 12:55 AM, Ron Roy wrote:
> Hi Jon,
>
> GB has some shale in it - I assume there are some trace oxides
> amounts in
> the shale that help whatever happens to form red crystals from tin and
> chrome - if that is the case - ball clays would have more trace
> oxides than
> kaolin would.
>
> When I look at the analysis for EPK I see 0.30% TiO2 - for the ball
> Clays I see
> 1.20,1.50, .90,1.80,1.40 - in other words a lot more. In this case
> John
> used OM#4 which has a typical analysis for TiO2 at 1.20% - 4 times the
> amount of TiO2. TiO2 helps crystals start forming - gives them
> something to
> start building on. Is it the same thing with crystals of sugar helping
> fudge solidify?
>
> I also see more TiO2 in Tile6, Helmer, and Pioneer kaolins -
> perhaps they
> would have worked as well - especially Helmer with 1.13% TiO2?
>
> I think - if kaolin is less than 10% of a glaze - there is a big
> advantage
> to subbing ball clay - better suspension and a harder dry glaze
> surface -
> way less powdering when pots are handled after glazing.
>
> You would need 13.5 OM #4 to replace 10% EPK in a glaze (and lower
> silica
> by 3.5 because ball clay has less alumina than EPK and more silica.
>
> If suspension did not improve enough - adding 1 or 2% bentonite
> would most
> likely do the trick - ball clay and bentonite work better together
> than
> bentonite and kaolin.
>
> Doing these kinds of materials substitution is best done using
> calculation
> software by the way - or get someone who does know how to use it to
> do it
> for you. It does work well and can solve many problems.
>
> RR
>
>
>> why would one sub ball clay for the EPK when doing this? what is the
>> advantage?
>>
>> thanks,
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>>
>>> Hi Bill,
>>>
>>> You are right particularly if people try 1 for 1 substitution. I
>>> have
>>> found the best way to make this particular substitution is to match
>>> the unity formula AND replace any EPK with ball clay. That was the
>>> only way I was able to find a good frit-based chrome/tin pink after
>>> many tries--thanks to a suggestion from Ron Roy at the height of my
>>> frustration. I'm not saying it can't be done other ways, but this is
>>> what worked best for me.
>>>
>>> Regards,
>>>
>>> John
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
Bill Merrill on fri 10 oct 08
Ron,
Ron,
Where did you find the fact Gertsley Borate has slate it's composition.
I am interested as the original Colemanite (2CaO.2B2O3.5H2O) One reason
true colemanite wasn't used much was because the 5H20 content was so
high even when dry, it would make the glaze pop off during the beginning
of a firing.
Gertsley Borate is what we sub for Colemanite now and I haven't found
where the slate idea comes from. Ulexite (NaCaB5O9*8H2O) (hydrated
sodium calcium borate hydroxide)is a basic formula for Gertsley Borate.
I didn't see that slate has any B203 in it. Where shall I find the
slate/Gertsley Borate connection.
Regards,
Bill
Ulexite (NaCaB5O9*8H2O) (hydrated sodium calcium borate hydroxide)
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of jonathan
byler
Sent: Friday, October 10, 2008 10:13 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Gertsley Borate.
ron,
thanks for the explanation. When I do some more tests I will try
recalculating for the ball clay instead of using epk. I suppose one
could add a pinch of TiO2, but then you wouldn't have the added
benefits of the better suspension properties you mentioned.
-jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Oct 10, 2008, at 12:55 AM, Ron Roy wrote:
> Hi Jon,
>
> GB has some shale in it - I assume there are some trace oxides
> amounts in
> the shale that help whatever happens to form red crystals from tin and
> chrome - if that is the case - ball clays would have more trace
> oxides than
> kaolin would.
>
> When I look at the analysis for EPK I see 0.30% TiO2 - for the ball
> Clays I see
> 1.20,1.50, .90,1.80,1.40 - in other words a lot more. In this case
> John
> used OM#4 which has a typical analysis for TiO2 at 1.20% - 4 times the
> amount of TiO2. TiO2 helps crystals start forming - gives them
> something to
> start building on. Is it the same thing with crystals of sugar helping
> fudge solidify?
>
> I also see more TiO2 in Tile6, Helmer, and Pioneer kaolins -
> perhaps they
> would have worked as well - especially Helmer with 1.13% TiO2?
>
> I think - if kaolin is less than 10% of a glaze - there is a big
> advantage
> to subbing ball clay - better suspension and a harder dry glaze
> surface -
> way less powdering when pots are handled after glazing.
>
> You would need 13.5 OM #4 to replace 10% EPK in a glaze (and lower
> silica
> by 3.5 because ball clay has less alumina than EPK and more silica.
>
> If suspension did not improve enough - adding 1 or 2% bentonite
> would most
> likely do the trick - ball clay and bentonite work better together
> than
> bentonite and kaolin.
>
> Doing these kinds of materials substitution is best done using
> calculation
> software by the way - or get someone who does know how to use it to
> do it
> for you. It does work well and can solve many problems.
>
> RR
>
>
>> why would one sub ball clay for the EPK when doing this? what is the
>> advantage?
>>
>> thanks,
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>>
>>> Hi Bill,
>>>
>>> You are right particularly if people try 1 for 1 substitution. I
>>> have
>>> found the best way to make this particular substitution is to match
>>> the unity formula AND replace any EPK with ball clay. That was the
>>> only way I was able to find a good frit-based chrome/tin pink after
>>> many tries--thanks to a suggestion from Ron Roy at the height of my
>>> frustration. I'm not saying it can't be done other ways, but this is
>>> what worked best for me.
>>>
>>> Regards,
>>>
>>> John
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
Ron Roy on tue 21 oct 08
Hi Jon,
It would be interesting to do some with say some EPK and a little Red Art -
which is between shale and clay. You might even get the same result with
some ball clays and not others.
I'll be glad to help do the conversions if you tell me what ball clays you have.
R
>ron,
>
>thanks for the explanation. When I do some more tests I will try
>recalculating for the ball clay instead of using epk. I suppose one
>could add a pinch of TiO2, but then you wouldn't have the added
>benefits of the better suspension properties you mentioned.
>
>-jon
>
>
>jon byler
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on tue 21 oct 08
Hi Bill,
This is quite old and of the many Typical analysis I have for the material
- this is the only one that includes this info - It looks like it came from
Hammill & Gillespie May 29/92.
Boric Oxide B2O3 .......................28.0
Sodium Na2O .............................05.3
Calcium CaO ..............................20.6
Water of crystalization ...............25.0
Free water .................................00.3
Water insolubles (inert shales) ...18.7
Total ..........................................97.3
I have written in on the same page the following analysis for Calcined
Colmanite,
SiO2 - ...............4.5
Al2O3 ...............0.55
Fe2O3 ..............0.28
KNaO ...............0.33
CaO .................35.5
MgO ................01.75
SrO ...................01.0
B2O3 ...............48.0
Flourine ........... 0.18
Loss on ignition 7.8
Total .............. 99.89
Note - I assume the LOI is from carbonates.
I have lots more on the GB - I can copy and mail it if you think it will
be of use.
RR
>Ron,
>
>Where did you find the fact Gertsley Borate has slate it's composition.
>I am interested as the original Colemanite (2CaO.2B2O3.5H2O) One reason
>true colemanite wasn't used much was because the 5H20 content was so
>high even when dry, it would make the glaze pop off during the beginning
>of a firing.
>
>Gertsley Borate is what we sub for Colemanite now and I haven't found
>where the slate idea comes from. Ulexite (NaCaB5O9*8H2O) (hydrated
>sodium calcium borate hydroxide)is a basic formula for Gertsley Borate.
>I didn't see that slate has any B203 in it. Where shall I find the
>slate/Gertsley Borate connection.
>
>Regards,
>
>Bill
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Steve Slatin on mon 27 oct 08
Bill --
Let me jump in here, as there are a few things
that I do know just a little about in this mix.
Colemanite is a mineral -- composition given
as (Ca2-B6-O11 : 5 H2O) or as CaB3O4(OH)3 - H2O.
It is a secondary mineral; it is found only
in evaporative deposits in dry places like the
bottom of dry lake beds. It frequently develops
lots of very nice crystals, rock hounds love the
stuff.
Gerstley Borate is mine run ore -- mostly a mixture
of two different minerals; one of which is nominally
considered a mixture of Colemanite and Ulexite,
NaCaB5O9 : 8H2O. Ulexite is known as a very
special stone to rock hounds, who call the best
samples "TV Stone" -- it's like natural fiber
optic cable. But like all mine run ores, there's
lots of other stuff in the mix; I imagine that
the slate just happens to be a contaminant in the
ore that Gillespie buys. The contaminants from
the Chilean deposits in the northern desert may
be different -- but Gillespie never bought the
ore from them, AFAIK.
When Gerstley Borate became unavailable, Gillespie
decided to meet the requirement differently.
They start with minerals, not mine run ore, and
mix to approach the target of traditional
Gerstley Borate. So it's not a natural material,
with erratic composition, instead it's a specifically
manufactured mix. People say it's like a frit, and
in terms of its careful control it is, but it's not
fired to a glass and ground to powder like a frit is.
It's also not actually chemically identical to
the old Gerstley Borate, and it has a lower level
of 'impurities.' These 'impurities' Gillespie
will gleefully tell you, result in Gillespie
Borate being less dark than Gerstley. Shale,
of course, often contains considerable carbon,
and is dark in color. Less shale is probably
one of the differences -- a different COE is
another, and it doesn't suspend as nicely as
Gerstley did, which may result from not having
the shale -- which is sedimentary, compacted
clay -- in it.
Generally, in application, Gillespie Borate is
a suitable substitute, one for one, for Gerstley
Borate. But it isn't really the same.
Steve S
--- On Mon, 10/27/08, Bill Merrill wrote:
> Ron,
>
>
>
> Attached is a memo you sent to John Byler that started with
> "> Hi Jon,
>
> >
>
> > GB has some shale in it - I assume there are some
> trace oxides
>
> > amounts in
>
> > the shale that help whatever happens to form red
> crystals from tin and
>
> > chrome - if that is the case - ball clays would have
> more trace
>
> > oxides than
>
> > kaolin would."
>
>
>
> All I asked was where did you find that GB had slate in it?
> You sent me
> a 30 year old analysis of GB from Hammill & Gillispie.
> The GB they now
> make is called "Gillispie Borate". The formula
> is more pure than the GB
> used 30 years ago. It reacts the same as the older GB. No
> slate is
> listed in trace amounts.
Bill Merrill on mon 27 oct 08
Ron,=20
=20
Attached is a memo you sent to John Byler that started with "> Hi Jon,
>=20
> GB has some shale in it - I assume there are some trace oxides
> amounts in
> the shale that help whatever happens to form red crystals from tin and
> chrome - if that is the case - ball clays would have more trace
> oxides than
> kaolin would."
=20
All I asked was where did you find that GB had slate in it? You sent me
a 30 year old analysis of GB from Hammill & Gillispie. The GB they now
make is called "Gillispie Borate". The formula is more pure than the GB
used 30 years ago. It reacts the same as the older GB. No slate is
listed in trace amounts.
=20
You mentioned Red art clay being a slate like material. I have never
heard "slate like" when referring to Red Art. I always considered Red
Art a high iron plastic earthenware clay. I am confusing the issue
about slate with regard to red art? These are questions that I am
interested in or I wouldn't pose them on Clayart or to you.
=20
When you used red art did you use something like the following formula?
=20
Red Art Clay=20
Mol. Weight: 623.75
Category Clay
Fill Oxides Al2O3
Molecular Analysis:
K20 0.268 Al2O3 1.000 SiO2 6.647
Na2O 0.040 Fe2O3 0.274 TiO2 0.083
CaO 0.025 P2O5 0.007=20
MgO 0.239=20
=20
Top Materials>=20
Percentage Analysis
64.28 % SiO2=20
16.41 % Al2O3
4.07 % K2O=20
0.40 % Na2O=20
1.55 % MgO=20
0.23 % CaO=20
0.17 % P2O5=20
7.04 % Fe2O3
1.06 % TiO2=20
4.78 % L.O.I.
Bill
=20
-----Original Message-----
From: Bill Merrill=20
Sent: Friday, October 10, 2008 12:31 PM
To: 'Clayart'
Subject: RE: Gertsley Borate.
=20
Ron,
=20
Ron,
=20
Where did you find the fact Gertsley Borate has slate it's composition.
I am interested as the original Colemanite (2CaO.2B2O3.5H2O) One reason
true colemanite wasn't used much was because the 5H20 content was so
high even when dry, it would make the glaze pop off during the beginning
of a firing.
=20
Gertsley Borate is what we sub for Colemanite now and I haven't found
where the slate idea comes from. Ulexite (NaCaB5O9*8H2O) (hydrated
sodium calcium borate hydroxide)is a basic formula for Gertsley Borate.
I didn't see that slate has any B203 in it. Where shall I find the
slate/Gertsley Borate connection.
=20
Regards,
=20
Bill
=20
=20
=20
=20
=20
=20
Ulexite (NaCaB5O9*8H2O) (hydrated sodium calcium borate hydroxide)
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of jonathan
byler
Sent: Friday, October 10, 2008 10:13 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Gertsley Borate.
=20
ron,
=20
thanks for the explanation. When I do some more tests I will try
recalculating for the ball clay instead of using epk. I suppose one
could add a pinch of TiO2, but then you wouldn't have the added
benefits of the better suspension properties you mentioned.
=20
-jon
=20
=20
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
=20
On Oct 10, 2008, at 12:55 AM, Ron Roy wrote:
=20
> Hi Jon,
>=20
> GB has some shale in it - I assume there are some trace oxides
> amounts in
> the shale that help whatever happens to form red crystals from tin and
> chrome - if that is the case - ball clays would have more trace
> oxides than
> kaolin would.
>=20
> When I look at the analysis for EPK I see 0.30% TiO2 - for the ball
> Clays I see
> 1.20,1.50, .90,1.80,1.40 - in other words a lot more. In this case
> John
> used OM#4 which has a typical analysis for TiO2 at 1.20% - 4 times the
> amount of TiO2. TiO2 helps crystals start forming - gives them
> something to
> start building on. Is it the same thing with crystals of sugar helping
> fudge solidify?
>=20
> I also see more TiO2 in Tile6, Helmer, and Pioneer kaolins -
> perhaps they
> would have worked as well - especially Helmer with 1.13% TiO2?
>=20
> I think - if kaolin is less than 10% of a glaze - there is a big
> advantage
> to subbing ball clay - better suspension and a harder dry glaze
> surface -
> way less powdering when pots are handled after glazing.
>=20
> You would need 13.5 OM #4 to replace 10% EPK in a glaze (and lower
> silica
> by 3.5 because ball clay has less alumina than EPK and more silica.
>=20
> If suspension did not improve enough - adding 1 or 2% bentonite
> would most
> likely do the trick - ball clay and bentonite work better together
> than
> bentonite and kaolin.
>=20
> Doing these kinds of materials substitution is best done using
> calculation
> software by the way - or get someone who does know how to use it to
> do it
> for you. It does work well and can solve many problems.
>=20
> RR
>=20
>=20
>> why would one sub ball clay for the EPK when doing this? what is the
>> advantage?
>>=20
>> thanks,
>> jon
>>=20
>>=20
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>=20
>> On Oct 3, 2008, at 1:31 PM, John Hesselberth wrote:
>>=20
>>> Hi Bill,
>>>=20
>>> You are right particularly if people try 1 for 1 substitution. I
>>> have
>>> found the best way to make this particular substitution is to match
>>> the unity formula AND replace any EPK with ball clay. That was the
>>> only way I was able to find a good frit-based chrome/tin pink after
>>> many tries--thanks to a suggestion from Ron Roy at the height of my
>>> frustration. I'm not saying it can't be done other ways, but this is
>>> what worked best for me.
>>>=20
>>> Regards,
>>>=20
>>> John
>=20
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
Ron Roy on tue 4 nov 08
Hi Bill,
Yes - I used an analysis almost the same as you listed below.
Notice the LOI - very low for a clay - that is the first clue to it's nature.
Second - it is not a plastic "clay" it breaks up when thrown or hand built
by itself.
Think of it as somewhere between a clay and a slate - I think of it as
about 75% clay and 25% slate.
We have that same type of material up here in southern Ontario - they use
it extensively for brick making.
I don't recall where I heard of it's slate like nature - it sure fits if
you are trying to explain the difference between it and most of the clays
we use.
RR
>You mentioned Red art clay being a slate like material. I have never
>heard "slate like" when referring to Red Art. I always considered Red
>Art a high iron plastic earthenware clay. I am confusing the issue
>about slate with regard to red art? These are questions that I am
>interested in or I wouldn't pose them on Clayart or to you.
>
>
>
>When you used red art did you use something like the following formula?
>
>
>
>Red Art Clay
>
>Mol. Weight: 623.75
>
>Category Clay
>
>Fill Oxides Al2O3
>
>Molecular Analysis:
>
>K20 0.268 Al2O3 1.000 SiO2 6.647
>
>Na2O 0.040 Fe2O3 0.274 TiO2 0.083
>
>CaO 0.025 P2O5 0.007
>
>MgO 0.239
>
>
>
>
>Top >Materials>
>
>Percentage Analysis
>
>64.28 % SiO2
>16.41 % Al2O3
>4.07 % K2O
>0.40 % Na2O
>1.55 % MgO
>0.23 % CaO
>0.17 % P2O5
>7.04 % Fe2O3
>1.06 % TiO2
>
>4.78 % L.O.I.
>
>Bill
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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