Rebecca Barton on fri 28 jun 96
Hello All,
I've been lurking and learning since the winter and have finally come up with
a question that hasn't been answered before I could ask it.
How do people manage to produce raku pots with both copper flashes and well
defined crackle on them. Since the copper glazes need to be reduced quickly
and the crackles need to be waved around or cooled slightly before reducing
,the two types would seem to be mutually exclusive of each other. Yet I've
seen pots with both on them.
The only pots I've made with both have been at the expense of the fat white.
Any help solving in this mystery will be greatly appreciated. Thanks!
Becky Barton
Laurel, MD
dannon@ns1.koyote.com on sat 29 jun 96
>----------------------------Original message----------------------------
>Hello All,
>
> How do people manage to produce raku pots with both copper flashes
and well
>defined crackle on them. Since the copper glazes need to be reduced quickly
>and the crackles need to be waved around or cooled slightly before reducing
>,the two types would seem to be mutually exclusive of each other.
>
> Becky Barton
> Laurel, MD
>
>Becky,
Crackle glazes do not necessarily need to be "cooled". There are a number
of variables. The thickness of the glaze and the "fit" between glaze and
clay have a lot to do with the development of crackling. I have two
copper-blue glazes that go
from kiln to reduction as fast as I can get them there (a few seconds) and
they develop excellent crackle. They shrink more and faster than the clay.
If I'm sufficiently speedy, they are really interesting glazes. The slower
I am, the less so.
If I left them out to "cool" they would be a remarkably uninteresting pale
to dark turquoise. They would still crackle, however.
Both glazes will develop copper flashing (though my interest in these glazes
is not copper flashing but copper red from in-kiln reduction).
Experiment more. You may find that the thicker the glaze (within reason)
the larger the crackle; that the crackle will enlarge over a strongly curved
surface, a "crab's claw" crackle much sought after.
If your glaze does not perform satisfactorily, alter the glaze or the clay
to decrease the fit, so that the glaze has to "stretch" as it were, as it
cools. You'll get crackle.
Dannon Rhudy
And it is bloody hot in Texas. Raku definitely a late-night activity for
the forseeable future.
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