John Post on fri 30 jun 00
Hi Sue,
Here is a nice cone 6 glossy black that I use. It isn't a reformulation of
your friend's glaze, but it is very reliable. I had problems with the
Alberta slip settling in my bucket when I used a glaze similar to your
friends. This glaze doesn't have that problem.
This glaze does have quite a few materials. I didn't design it from
scratch. It is a revision of another glaze I used in the past. It had to
use this many materials to match the unity formula of my original glaze.
++++++++++++++++++++++++++++++++++++++++++++
+++ John's "Rotary Phone" Black ^6-7 +++
++++++++++++++++++++++++++++++++++++++++++++
Alberta Slip 3519 39.1%
Frit 3110 1791 19.9%
Bone ash 18 0.2% Hazard!
Wollastonite 1035 11.5%
Talc 297 3.3% Hazard!
EPK 1656 18.4% Hazard!
Flint 684 7.6% Hazard!
-------- ------
9000 100 %
Rutile 18 0.2%
Cobalt carbonate 261 2.9% Hazard!
Red iron oxide 144 1.6%
===========================
Chemical Analysis
===========================
Na2O 0.20 Al2O3 0.40 SiO2 3.06
K2O 0.05 B2O3 0.02 P2O5 0.00
MgO 0.18 TiO2 0.01
CaO 0.49 Fe2O3 0.06
CoO 0.08
Alumina:Silica ratio is 1.00 : 7.57
Neutral:Acid ratio is 1.00 : 7.33
Alkali:Neutral:Acid ratio is 1.00 : 0.43 : 3.14
Expansion coefficient: 74.6 x 10e-7 per degree C
John Post
Sterling Heights, Michigan USA
e-mail waverock@c3net.net
Website http://www.c3net.net/waverock
>Can someone suggest a
>simple (we hope) reformulation using something more common? She fires to
>cone 6 oxidation.
>
>Alberta Slip 85
>Gerstley Borate 10
>Cobalt Carbonate 5
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