Talc!
 

The writing on the wall is that the University is not going to allow us to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it is
the only thing that worked.

Donna

Talc!
 

"DKat" wrote in message
...
The writing on the wall is that the University is not going to allow us to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it is
the only thing that worked.

Donna


Talc adds magnesium to glazes and is used as a flux in some low fire clay
bodies to lower the maturing temperature and extend the firing range. It is
primarily used in white hobby and school type modeling clays. I'm not sure
what would substitute for it in a clay body, perhaps a frit or other
prepared fluxing agent. Or, perhaps dolomite and silica could serve this
purpose in a body.

Talc is magnesium silicate and provides both magnesium oxide and silica to a
glaze. Magnesium can be gotten fom dolomite which is a calcium, magnesium
carbonate or from chemical magnesium carbonate.

If substituting dolomite for talc, up the amount of silica in a recipe and
decrease the amout calcium carbonate, whiting, until the same equivalents
are in the recipe as before.

If substituting magnesium carbonate up the silica, but don't do anything to
the calcium.

If you know how to formulate glazes, this should be trivial. If you don't I
would be more than happy to propose an adjuted recipe for you to try.

Just post here or e-mail a favorite talc, glaze recipe and I'll take a stab
at modifying it for you to try. It should act in every way the same as the
original recipe because all of the elements will be the same, only from
different sources.

My e-mail address is montassocatyahoodotcom Please fix the at and dot.

Talc!
 

I can formulate glazes. I was hesitant to use Magnesium because I cannot
even image the volume I would need for the equivalent. Dolomite does not
work in the glazes that iis used because the calcium to magnesium ratio
doesn't work. One of the glazes is Randy's Red (ours is Toby's but very
similar).

Toby's Red ^6
32 gerstly
30 flint
20 kona f4
14 talc
5 epk
15.15 RIO

roughly goes to
32 gerstly
30 flint
20 kona f4
8 magnesium carb
15.15 RIO

When this gets upped to 10000grams that is 800 grams of Magnesium Carb....
That strikes me as a huge volume but I may be remembering wrong.

If you think this is worth the try, I will mix up a batch. Thanks, Donna


If you think I can use magnesium to replace the talc, I will work with that.
"Bob Eld" wrote in message
et...

"DKat" wrote in message
...
The writing on the wall is that the University is not going to allow us
to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone
and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it
is
the only thing that worked.

Donna


Talc adds magnesium to glazes and is used as a flux in some low fire clay
bodies to lower the maturing temperature and extend the firing range. It
is
primarily used in white hobby and school type modeling clays. I'm not sure
what would substitute for it in a clay body, perhaps a frit or other
prepared fluxing agent. Or, perhaps dolomite and silica could serve this
purpose in a body.

Talc is magnesium silicate and provides both magnesium oxide and silica to
a
glaze. Magnesium can be gotten fom dolomite which is a calcium, magnesium
carbonate or from chemical magnesium carbonate.

If substituting dolomite for talc, up the amount of silica in a recipe
and
decrease the amout calcium carbonate, whiting, until the same equivalents
are in the recipe as before.

If substituting magnesium carbonate up the silica, but don't do anything
to
the calcium.

If you know how to formulate glazes, this should be trivial. If you don't
I
would be more than happy to propose an adjuted recipe for you to try.

Just post here or e-mail a favorite talc, glaze recipe and I'll take a
stab
at modifying it for you to try. It should act in every way the same as the
original recipe because all of the elements will be the same, only from
different sources.

My e-mail address is montassocatyahoodotcom Please fix the at and dot.

Talc!
 

On Tue, 4 Dec 2007 14:28:02 -0500, "DKat"
wrote:

The writing on the wall is that the University is not going to allow us to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it is
the only thing that worked.

Donna



So, what is the University's reason for this? Is the about
the talc itself (magnesium silicate), or some impurity?
Considering that baby powder is talc, and the way
it is applied (through those shaker-top squeeze bottles)
puts a lot of it into the air, compared to a potter stirring
talc into a glaze, one has to wonder. Or is baby powder
now an endangered species as well?

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

Talc!
 

On Tue, 4 Dec 2007 23:38:51 -0500, "D Kat"
wrote:

I can formulate glazes. I was hesitant to use Magnesium because I cannot
even image the volume I would need for the equivalent. Dolomite does not
work in the glazes that iis used because the calcium to magnesium ratio
doesn't work. One of the glazes is Randy's Red (ours is Toby's but very
similar).

Toby's Red ^6
32 gerstly
30 flint
20 kona f4
14 talc
5 epk
15.15 RIO

roughly goes to
32 gerstly
30 flint
20 kona f4
8 magnesium carb
15.15 RIO

When this gets upped to 10000grams that is 800 grams of Magnesium Carb....
That strikes me as a huge volume but I may be remembering wrong.

If you think this is worth the try, I will mix up a batch. Thanks, Donna

I don't think you can use magnesium carbonate... the glaze will
crawl off the pot and out of the studio!

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

Talc!
 

Thanks Bob. I figured there had to be some reason Magnesium carb wasn't
being used. Nice to know before I invest the time.
Donna
"Bob Masta" wrote in message
...
On Tue, 4 Dec 2007 23:38:51 -0500, "D Kat"
wrote:

I can formulate glazes. I was hesitant to use Magnesium because I cannot
even image the volume I would need for the equivalent. Dolomite does not
work in the glazes that iis used because the calcium to magnesium ratio
doesn't work. One of the glazes is Randy's Red (ours is Toby's but very
similar).

Toby's Red ^6
32 gerstly
30 flint
20 kona f4
14 talc
5 epk
15.15 RIO

roughly goes to
32 gerstly
30 flint
20 kona f4
8 magnesium carb
15.15 RIO

When this gets upped to 10000grams that is 800 grams of Magnesium Carb....
That strikes me as a huge volume but I may be remembering wrong.

If you think this is worth the try, I will mix up a batch. Thanks, Donna

I don't think you can use magnesium carbonate... the glaze will
crawl off the pot and out of the studio!

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

Talc!
 

Apparently Ceramic Supplies (NJ) gets its talc from a mine in Connecticut
where the talc has been contaminated with asbestos. The University
Environmental 'police' confiscated our talc and were going to take our
glazes made with talc. They were talked out taking the glazes. I learned
this morning that we are going to try to get a replacement talc from
Texas...

I keep on swearing I'm not going back into the studio yet I keep finding
myself there.

.....

Donnna

"Bob Masta" wrote in message
...
On Tue, 4 Dec 2007 14:28:02 -0500, "DKat"
wrote:

The writing on the wall is that the University is not going to allow us to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it is
the only thing that worked.

Donna



So, what is the University's reason for this? Is the about
the talc itself (magnesium silicate), or some impurity?
Considering that baby powder is talc, and the way
it is applied (through those shaker-top squeeze bottles)
puts a lot of it into the air, compared to a potter stirring
talc into a glaze, one has to wonder. Or is baby powder
now an endangered species as well?

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

Talc!
 

"DKat" wrote in message
...
Apparently Ceramic Supplies (NJ) gets its talc from a mine in Connecticut
where the talc has been contaminated with asbestos. The University
Environmental 'police' confiscated our talc and were going to take our
glazes made with talc. They were talked out taking the glazes. I learned
this morning that we are going to try to get a replacement talc from
Texas...

I keep on swearing I'm not going back into the studio yet I keep finding
myself there.

....

Donnna

"Bob Masta" wrote in message
...
On Tue, 4 Dec 2007 14:28:02 -0500, "DKat"
wrote:

The writing on the wall is that the University is not going to allow us
to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone
and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute it
especially given that I have used it to keep glazes from crazing and it
is
the only thing that worked.

Donna



So, what is the University's reason for this? Is the about
the talc itself (magnesium silicate), or some impurity?
Considering that baby powder is talc, and the way
it is applied (through those shaker-top squeeze bottles)
puts a lot of it into the air, compared to a potter stirring
talc into a glaze, one has to wonder. Or is baby powder
now an endangered species as well?

Best regards,


Bob Masta

try baby powder on sale at walmart. read the label, as some baby powder is
really corn starch.

Talc!
 

"D Kat" wrote in message
...
I can formulate glazes. I was hesitant to use Magnesium because I cannot
even image the volume I would need for the equivalent. Dolomite does not
work in the glazes that iis used because the calcium to magnesium ratio
doesn't work. One of the glazes is Randy's Red (ours is Toby's but very
similar).

Toby's Red ^6
32 gerstly
30 flint
20 kona f4
14 talc
5 epk
15.15 RIO

roughly goes to
32 gerstly
30 flint
20 kona f4
8 magnesium carb
15.15 RIO

When this gets upped to 10000grams that is 800 grams of Magnesium Carb....
That strikes me as a huge volume but I may be remembering wrong.

If you think this is worth the try, I will mix up a batch. Thanks, Donna


If you think I can use magnesium to replace the talc, I will work with
that.
"Bob Eld" wrote in message
et...

"DKat" wrote in message
...
The writing on the wall is that the University is not going to allow us
to
use Talc either in our glazes or our clays (how in the world you are
supposed to find that out given the mix we have that has come and gone
and
the recycling done...).

Our best glazes use Talc. What in the world can you do to substitute
it
especially given that I have used it to keep glazes from crazing and it
is
the only thing that worked.

Donna



It sounds like you have it in hand and can reformulate if necessary but with
Texas talc or another source, that may not be necessary.

I was trying to look at the molecular formulas and can't find, in this short
time, a proper formula for Gerstly Borate, Some references are giving the
formula for Colemanite under Gerstly but they are not the same. Furthemore,
I understand the Gerstly mine has closed which means you may have to
re-formulate anyway regardless of the talc issue. Thoughts?

I will still play around with formulations as time permits and post them
here.

BTW, the above formula just replaces talc with magnesium carbonate but does
not adjust the silica or the lime in the Gerstly. The silica and alumina
balance is even worse because there is no kaolin. It would probably give
very different results.

Talc!
 

"charlie" ) writes:
"DKat" wrote in message - snips -
...
Apparently Ceramic Supplies (NJ) gets its talc from a mine in Connecticut
where the talc has been contaminated with asbestos. The University
Environmental 'police' confiscated our talc and were going to take our
glazes made with talc. They were talked out taking the glazes. I learned
this morning that we are going to try to get a replacement talc from
Texas...

Donnna

try baby powder on sale at walmart. read the label, as some baby powder is
really corn starch.


Talc occurs in association with asbestos. This is why most, if not
all, baby powders are corn starch. Adult powders might be more likely
to have talc. I'd imagine that any talc source could end up containing
asbestos as they went from one end of the mine to the other. And like
any sort of contamination, the government can change the allowable parts
per million or whatever.

The Canadian government is still trying to mine and sell asbestos
as an insulation. It's doing this because there are great quantities
of it in Quebec. But it generally* can't be sold in Canada and there are
fewer and fewer takers because the stuff is so bad for the lungs.


Elaine


* my source says some precast concrete can have asbestos.