Lili Krakowski on thu 13 nov 08
Well. To the question "Are you making yourself neurotic" my
whimsical answer is,
if you already are in clay, Gull, you probably are as neurotic as
the rest of us!
Now. As to cones, and as to bisquing.,
Hermann Seger a German clay scientist invented cones in the late
19th Century.
He called them "bowling pins", as they still are called in
German, and these cones
measured heat. He started at cone 1 and went up--not sure to
what number.
The he realized that he needed them for low temperatures as
well...and so he created
a new set of cones that started at 01 and went down to whatever.
This has been a headache maker
for over a century [!] because cones go UP from 1 to whatever,
but DOWN from 01 to whatever.
Much like minus numbers.
Edward Orton Jr in the US adapted the Seger cones and while
keeping the
numbering system, changed them so that they measure work, not
heat only.
This is a huge help as what "we" want to know is "Is this glaze
cooked?" not really
"How hot is this glaze?" (If you ever have roosted a chicken you
will appreciate
the difference.)
It should be added--and noted--that when one reads a British or
other non-US book
on glazes the cones indicated may be Seger cones, not
Orton--though Orton has gotten
pretty international. In other words a glaze temp. given in
Seger cones may not
give a perfect result at a Seger cone of the same number. Books,
however, provide charts.
Bisquing is not necessary. Many potters single-fire which means
they apply
glaze to their "raw" pots and then fire very very slowly, going
through the bisque
temperatures and then, after a certain point firing faster.,
There are very good
books on single firing, so I will not go into its merits.
We bisque because it makes the clay far more resistant. We can
handle
it more easily, it can be stacked with less risk of chipping,
and the pot
can be glaze more easily. Also: In the bisque, organic matter
burns out,
the gases created by that burning out escape, and so the glaze
has an easier
time fusing and healing and all that.
We bisque at low temperatures: I would say c.06 to c.04. This
leaves the
clay very porous which makes glaze application, and the handling
of the
pots easier.
So: In bisquing to the maturity cone of your clay body you not
only have wasted
electricity., but you have made glazing harder on yourself. Yes
one can put greenware
and gloss ware in the same kiln...but why? If you bisque fire
separately you actually
gain space, as the pots-to-be-bisqued can be stacked, and they
can touch
each other--and many, and sometimes I.--.fire bisque without
shelves, just stacking
the pots. I get about 3 glaze kilns out of one bisque.
As to the use of your pots--that really has nothing to do with
how you bisque--just that the pots
in final state--are safe...
Lili Krakowski
Be of good courage
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