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reds and copper

updated sat 14 nov 09


Nils Lou on fri 13 nov 09

I agree that reducing early, 012, helps greatly in copper red glazes.
A turbulent atmosphere, ie., well stirred reduction, is needed to=3D20
pull off the Oxygen atom and reduce to metallic copper. If the =3D
is uneven we the copper remains as CuO and we get white. Also, if there=3D2=
is flame impingement volatilized color can be lost. In a kiln that fires
unevenly this may be the problem. One thing to try then is after glazing
with the copper glaze apply a thin coating of C06 clear (a commercial =3D
works fine. The idea here is that this seals the glaze after reducing =3D
the copper
at C012 and prevents subsequent volatilizing. I have done this with some =

copper reds that were problematic. Pete Pinnells reds and variations are =
automatic in my school kilns. Reduce at C012, hold light reduction to =3D
the finish,
shutdown and let cool. No fire down, just open 24 hours later for nice =3D
strawberry, raspberry, and cool, bluish reds.=3D20
I have an older Alpine that is the workhorse for advanced students. We =3D
all the curved bag walls and lined the flame trenches with one inch =3D
fiber. This seems to "fluff" up the flame, creates turbulence, and fires =
in 7 hours--very evenly. Dampers are set to 2" on top, gas pressure (NG) =
2-3/4 inches of WP. Start up and go. No changes needed start to finish.=3D2=
I have developed an oxyprobe with no platinum, using K-type =3D
thermocouple, reads to
meter with direct temp. readout to C=3DB0. Will be available for under =3D
$500 in 2010.
Stay tuned.=3D20

nils lou, professor of art
"Play is the essence of creativity", and
"What is not brought forward into consciousness....
we later call Fate", Carl Jung