Jeff Lawrence on thu 10 dec 98
Veena and Greg were asking about a technique
>whereby
>one may enhance the colors of a piece raku fired with a copper glaze by
>brushing on a solution of 10% frit and 90% black copper oxide, then heating
>it with a propane torch.
Hello Veena & Greg,
In the course of perfecting my livery copper reds at ^6, my friend Ray
tried the following on one of the many brown pots I've produced:
- brushed on a solution of potassium carbonate (CAREFUL: dont get it on
your hands!! Even after it's dried!! CAREFUL!)
- played the flame of a propane torch over it
The result was a ghost-like kaleidoscope of iridescent metallics, of
different colors as the heat had been different. Looked incredible under a
glass but was faint under normal ocular magnification. Ray spieled off a
bunch of geologo-speak at me, including "malachite, azurite...which should
be stable." He seemed to think that the evanescence of raku colors wouldn't
apply to these. He also seemed to think that soda ash or lithium carbonate
would produce similar effects.
This was a glaze that had very little metal in it -- less than .2% red
copper oxide and .75% tin oxide. The previous firing -- an experiment in
heavier reduction to make sure my pots would be just as ugly in that
circumstance -- had produced metallic blooms on the surface, which became
the foci for the new colors. I suspect that trying it with a higher
metallic content would increase the color response.
If you try this on a raku pot, please post the results.
Jeff
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt. 1 Box 394L
Espanola, NM 87532
vox/fax 505-753-5913
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