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glaze test for purple opal, cone 6 ox.

updated fri 4 feb 05


Alisa Clausen on thu 3 feb 05

Glaze test for Purple Opal, cone 6 ox.

Glaze tested on white midrange stoneware fired in electric oxidation to =
1240c. (2264f)

Source: Clayart
Credited to:

Firing ramp:
100c p/h to 600c (212f - 1112f)
150c p/h to 1140c (302f - 2084f)=20
80c p/h to 1240c (176f - 2264f)
5 min. soak
cool down max. to 800c (1472f)
Hold 1 hour
Shut off kiln

14 Gerstely Borate
30 Spodumene
7 Dolomite
13 Talc
20 Silica

6 Rutile
1 Manganese Diox.
Underlying glaze is a mat tan. Over the mat tan ground is a streaky =
white and opalescent gloss shell. Overall, the glaze is tan with white, =
feathery streaking.

2 Cobalt Carb.
A dark blue purple mat glaze.

4-6 Copper Carb.
A semi mat glass green glaze.

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

Regards from Alisa in Denmark