Janet H Walker on mon 2 feb 98
...Jr. cones bend at a different temp...
True but there is more to it than that. They are also calibrated
at a much higher rate of temp rise. If you look at the charts, they
say soemthing like such-and-such degrees at 580/hr heat rise. Now
that's a MAJOR ramp up in temp. Beyond the capabilities of most kilns,
well most electric kilns anyhow. I don't know what on earth the junior
cones were first designed for but they are like apples and oranges with
the full size cones which are calibrated for 60C/hr or 150C/hr heat rise
(note the two different temps, depending on the rate of heating.)
So if you want your cone 6 to mean the same thing as someone else's,
you'll be using the full size cones. The kiln sitters generally are
backup mechanisms and what you want in there is something that will
melt before the pots and kiln furniture so you make it something that
won't melt before your full size cones tell you that you are finished.
I have found that I have to use ^8 junior cones in my sitter in order
to get a firing that the full size cones report as almost ^6.
OK?
Jan Walker
Cambridge MA USA
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