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results: copper carbonate in glaze- luster effect - local

updated sat 20 nov 04

 

Ron Roy on fri 19 nov 04

reduction?

Hi May,

It's just the oversaturation of copper - not reduction that is doing it -
thats copper on the surface of the glaze. Try a lemon slice on it.

Reduced copper will have at least some red in it.

RR


>In my high alkaline currie grid test, I painted copper carbonated on parts
>of the grids. It appears that the copper to from green - mild luster effect
>[at a certain saturation point] - brown black [very saturated].
>
>Is this an indication of local reduction? I have a poorly ventilated
>electric kiln - no fancy ventilation like the American versions. If so, how
>do I improve it so that the reduction does not weaken with my elements
>
>Or it's the copper coming out in different formation [CuO, Cu2O,
>CuCO3.Cu(OH)2, 2CuCO3.Cu(OH)2] because of variation in silica and alumina
>levels. I have same observation with another high alkaline currie grid with
>Copper Carb mixed into the glaze, but different flux set.
>
>TIA
>May

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513