Terri Chesney on thu 14 aug 97
#1
I wondered in Tony Hansen or anyone else figured out the deal with the
cones that bent weird or broke off at the base. We had a lot of this when
our cones were -anywhere- near the peep holes. Anyone else figure it out?
Did the problems stop?
#2
Does anyone know of a glass window that could be installed in a kiln to see
the inside without opening the peep hole? I have considered casting a
tunnel to the outside of our kiln (about 6-7") and putting the glass there.
Then I would let the glass leak a tiny bit to cool it off. The idea is to
keep the glass cool enough to not melt or to be dangerous. Is there a
scientific glass that will take a great deal of heat? We fire to 2450 F but
we have a downdraft with a strong negative atmosphere-firing with wood. Air
leaking around the glass would cool it. Maybe a coated glass to reflect the
UV and IR rays? Any ideas? We have a kiln that is viewed by a large number
of visitors.
Thanks for the input.
Pat Chesney
Pat-Chesney@easy.com
Waco, Texas
Louis Katz on fri 15 aug 97
The properties and uses of Orton Standard Pyrometric Cones 5th edition
October 1978 page 13 bottom states, " kiln atmospheres which are
sulphurous or reducing may cause cones to develop a rigid "shell" with an
interior that becomes fluid, therefore, producing erratic
deformation.............
"Hard Shelling" may also be encountered with regular cones 010 through 03
in a high velocity or prolonged firing in a combustion atmosphere. This
type of hard shelling is caused by volatilization of B2O3 from the frit
in the presence of moist air........"
Being near an open spy or at the edge of a shelf can increase the
velocity of gases the cone is exposed to. I have had problems with
hardshelling only in kilns that have been accidentilly reduced below red
heat, fired for long periods of time, or had large quantities of brick
clay in them.
Louis
Louis Katz
Texas A&M University Corpus Campus
lkatz@falcon.tamucc.edu
NEW WEBSITE:http://maclab.tamucc.edu/lkatz/lkatz/index.html
Terrance Lazaroff on wed 20 aug 97
Pat;
If your cones are breaking off at the base then it is most likely you are
reducing too much, too early during the firing.
Terrance
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