John Baymore on mon 11 sep 00
The easiest and safe way to see your witness cones is to brush them with
red
iron oxide mixed with a little water. Someone mentioned it on Clayart
several
months ago and it works like a charm!
Ceramics is so complicated and there are so many interrelated variables!
While this practice appears to solve one problem.... it can easily create=
another. Painting ANYTHING that contains ceramic chemistry on a cone can=
change its bending behavior. If you are utilizing clay and glazes that a=
re
tolerant of much variation in the ultimate firing cone... then this will
not show up as problems. But if your materials / formulations are
finicky... then you can start having fired results problems.
The there is the whole issue of how MUCH exteraneous stuff is being paint=
ed
on by each differnt person, the exact nature of the material used (is it
the same composition of raw material for each person?), and so on. Tons =
of
possible variables.
If you do this "paint the cones" practice .......... and there are no
firing problems evident........ then I guess you can just "have at it". =
But be aware that if you change some of your clay/glaze materials or
formulas... suddenly you might have problems.
Because ceramics is so full of technical complexities..... we often find
that what works OK for one person does not work for another. (Glaze
formulas are notorious for this one ) This is usually because some oth=
er
undisclosed (or often unknown) variable )or multiple variables) is also a=
t
work either making it work in one case... or making it not work in the
other. It is sort of like a case of programming logic...... =
If you do THIS, then you must also DO THIS other thing ELSE you get this
negative result.
(Terrible example really, I guess................ Maybe IF a AND b
THEN c ELSE d would be closer.)
Just a little "heads up" that while it can work for some....there is no
guarantee that it will work in all cases.
By the way.......... the advice to be very careful when blowing in spyhol=
es
to cool the cones (and clear reduction flame) so that can be seen is good=
stuff. The brick dust can ruin stuff easily. In the kilns I build for
people, in order to help with this issue, the spy ports are either lined
with a solid hard refractory type tube or the softbrick of the wall is
carefully coated with a refractory coating cement to prevent much routine=
softbrick dusting. Ditto for the spyport plugs. Then I recommend to the=
kiln owner that they also clean out the ports routinely with sponge and
water or a HEPA vacume as part of the routine maint. that leads up to a
firing. =
Best,
......................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JBaymore@compuserve.com
John.Baymore@GSD-CO.com
"Earth, Water, and Fire Noborigama Woodfiring Workshop August 18-27,
2000"
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