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copper reds and zinc oxide

updated sat 27 oct 01


WHC228@AOL.COM on fri 26 oct 01

I am always confused about copper reds. Most folks that write about copper
reds agree that reducing from early on is important. then I look at photos of
wonderful copper reds that were reduced in an electric kiln that had an oil
drip or gas added when the kiln was in its cooling cycle. I have no
experience with that, however I just got set up to do that in one of my
Zinc oxide is an important ingredient in the glazes that I do. They are rich
in both zinc oxide and titanium dioxide. My glazes will not work without the
zinc. My experience has taught me that if my reduction is done too early the
oxide will turn the zinc oxide into the metal zinc. Since zinc boils at such
a low temperature I am assured plenty of zits on the surface if that happens.
I do plenty of reduction, but wait until the zinc oxide has melted and is
incorporated into the rest of the ingredients. I really do not know if that
is really what is happening, but it works for me.
I did do some testing with some frits that are high in zinc. The reason for
that testing was to be able to reduce early without the zinc doing its
bothersome pitting thing. It worked pretty well. I didn't pursue it because
It would have meant fixing something that wasn't really broken.
I believe that the amount of calcium in the glaze has a lot to do with how
the zinc oxide works. The combination seems to be essential in my glazes.
Bill Campbell