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glaze test for marcia's (selsor) mat and 3 revsions, cone 6, redux,

updated wed 8 jun 05


Alisa Clausen on tue 7 jun 05

fired in oxidation.

Glaze test Marcia's (Selsor) mat and 3 revisions, cone 6, redux, fired =
in oxidation.
Glaze tested on white midrange stoneware fired in electric oxidation to =
1220c. (2228f)

Source: Clayart and other
Credited: Marcia Selsor, Charles Moore and Ron Roy

Firing ramp:
100c p/h to 600c (212f - 1112f)
150c p/h to 1140c (302f - 2084f)=20
80c p/h to 1220c (176f - 2228f)
15 min. soak
cool down max. to 1100c (2012f)
Hold 1 hour
Shut off kiln

Marcia's Mat
23 EPK
20 Dolomite
38 Neph. Syenite
18 Silica
4 Whiting
10 Gerstley Borate
113 gr.

Note: All raw materials are measured up or down to the nearest half =
decimal. =20
Colorants or additives to a 100 gram test batch are measured in percent =
to the 100 gram test batch.

Mat, soft white, covering glaze. Typical Dolomite mat surface, smooth =
and nicely melted at cone 6.

Charles Moore did two revisions using his glaze calculation program, =
Insight, getting the glaze to fit John and Ron's parameters of a stable =

Charles Moore Rev. 1 (Marcia's Mat Charles)
20 EPK
17.5 Dolomite
33.5 Neph. Syenite
16 Silica
2.5 Whiting
9 Gerstley Borate
98.5 gr.

Mat, soft white, covering glaze. This version is visually almost =
identical to Marcia's original recipe, however, it is a tiny bit drier =
on the surface. Still, well melted and
has a smooth feel.

Charles Moore Rev. 2 (Marcia's Mat Chas 2)
20 EPK
17.5 Dolomite
33.5 Neph. Syenite
30 Silica
2.5 Whiting
9 Gerstely Borate
112,5 gr.

You've done it Charles!
This version is a soft white, covering, silk mat glaze. It is my =
personal favorite type of surface, a smooth to touch, milky white, =
silky, well melted, semi mat. =20
The glaze is slightly more reflective than both versions above, but =
still mat, with a very smooth feel to the surface. Just makes me want =
to pass the test tile
across my cheek.
Good work Charles!

Ron Roy's Revision (error?)
15 EPK
24 Dolomite
13 Neph. Syenite
2 Silica
14 G200 Spar
15 Frit 3134
83 gr.

This is a revision I received long ago from Ron.
I think I got something wrong in the recipe, because it is so low in =
Silica. It may have been 20 Silica instead of 2.
This recipe was mat and smooth, but crazed, a sign that the Silica is =
too low.

Regards from Alisa in Denmark