"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.