Alisa Clausen on wed 27 feb 08
Glaze test for Post Calcium Mat #7
Source: Clayart
Credited to: John Post
Fired on mid fire white stoneware
Firing ramp with an electric controller is:
100c p/h to 600c (212f - 1112f)
150c p/h to 1140c (302f - 2084f)
80c p/h to 1220c (176f - 2228f)
15 min. soak
cool down max. to 900c (1652f)
Hold 30 minutes
Shut off kiln
Colorants or additives to a 100 gram batch are measured in percent to the
100 gram batch.
Standard Substitutions in all tests:
Local Boron Frit is used for Frit 3134
Forshammer (a half and half Potash and Soda spar) is the only Feldspar used
Local Boron Frit is used for Gerstley Borate
All substitutions are done not by Mol. Wts., but gram for gram.
Recipe Name: Post Calcium Mat
Cone: 6 Color:
Firing: Oxidation Surface: Mat
Amount Ingredient
30.2 Ball Clay--Old Mine #4
5.7 Frit--Ferro 3134
32.5 Nepheline Syenite
16.3 Wollastonite
4.9 Whiting
10.4 Silica
100 Total
Additives
6 Iron Oxide--Red
3.5 Titanium Dioxide
Unity Oxide
.218 Na2O
.066 K2O
.035 MgO
.681 CaO
1.000 Total
.554 Al2O3
.065 B2O3
.009 Fe2O3
3.338 SiO2
.016 TiO2
6 Ratio
7.4 Exp
Comments:
Semi Mat, covering glaze. Medium brown overall, slightly dry.
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