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glaze test for crystal glaze, light green/blue, orange/blue,

updated sat 14 sep 02


Ron Roy on fri 13 sep 02

cone 6, ox.

Not a stable glaze for functional ware - Taylor and Bull report greater
leaching of glaze between crystals under acid - this because the crystals
rob it of silica when they form.

Lithium at 7% can result in fit problems with some clays - test well.


>Glaze test for Crystal Glaze, Light Green/Blue, Orange/Blue, cone 6, ox.
>Glaze tested on white midrange stoneware fired in electric oxidation to 1220c.
>Credited to:
>Firing ramp:
>100c up/he to 600c (212f - 1112f)
>150c up/he to 1100c (330f - 2012f)
>100c up/he to 1220c (212f - 2228f)
>cool down max. per hour to 1100c
>cool 80c per hour to 800c
>shut off kiln
>5 Kaolin
>15 Flint
>24 Zinc Oxide
>13 Whiting
>7 Lithium Carb.
>36 Feldspar
>For light green with blue crystals
>5 Rutile
>1 Copper Carb.
>For Orange with blue crystals
>1 Nickel
>Note: All raw materials are measured up or down to the nearest whole
>Colorants or additives to a 100 gram test batch are measured in percent to
>the 100 gram test batch.
>Substitutions: None
>Lt. Green with blue crystals
>Fluid gloss glaze with turquoise ground and large green crystals. Where
>glaze pooled, looks like an aerial view of the Caribbean islands.
>Orange with blue crystals
>Orange to rust transparent ground with large light blue crystals with dark
>blue crystals inside.
>Personal: This is the first time I tried crystal glazes, and these two
>variations are amazing. The test tiles are like precious gems.
> The crystals have such clear structures and the formations
>are look geographical.

Ron Roy
15084 Little Lake Road
Brighton, Ontario
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513