Heloisa Nunes on fri 13 oct 06
Hello Clayarters,
Finally I am back to clayart with some results of glaze tests.
I will try and post them similar to Alisa's models which is I love and it is
SOO nice.
Thanks, Alisa!
Glaze test for Leather
Source: Clayart - Alisa Clausen
Credited to ?
Clay: white stoneware cone 6-8
Fired to cone 6 (2185F) in oxidation.
Firing ramp used :
38 C (100 F) per hour to 104 C(220 F)
176 C (350 F) per hour to 1093 C(2000 F)
42 C (108 F) per hour to 1196 C (2185 F) hold 15 min
260 C(-500 F) per hour to 1037 C(1900 F) hold 10 min
482 C(-900 F) per hour to 760 C(1400 F)
Shut off and cool naturally, opening below 51 C (125 F).
Recipe (all ingredients brazilian except when marked):
Dolomite 21
Gerstley Borate 10
Spodumene 9
Wollastonite 5 (*** Canadian)
Custer Spar 27
Neph. Syenite 12
Kaolin 16
Add: 5% RIO
Test: All raw materials measured up or down to nearest whole decimal in a
1000 gram batch test.
Substitutions: Colemanite for Gerstley
Results:
I did have some problems with sieving in my # 80 mesh sieve. There was some
sparkly white stuff that looked like sand that was held by the sieve. It was
more like a full hand which I could not ID what was it. I just threw it back
in the bucket and prayed that it was not going to make a mess with my test.
My supplyier swore that everything was 325 mesh...Well...
The result was a brown to greenish color, mat where thinner, it ran a little
where very thick. It seemed fully melted and it has a glimmer that I loved.
I imagine that the white base must be beautiful. I
personally did not like the shade of brown color because it reminds me of
poop color...I hope I can fix the batch with some more RIO and Cobalt oxide
to achieve a nice dark brown to black. I think I should also increase
alumina which it on the low side.
Well, I throw this one to the experts and I will post the other results of
other recipes that many sent to me(THANK YOU AGAIN!!! )to help develop
glazes
that I like with materials here.
Thank you all for your help and cheers from sunny São Paulo.
Heloisa Nunes,
São Paulo, Brazil
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