Mike Gordon on wed 9 jul 03
A question about cone temps. While the roofers were ripping off my old
roof I had some down time to do some reading. In Glen C. Nelson's book
he lists Orton cone temps for large and small cones. I wrote these down
for future reference. Then I picked up a glaze book by Richard Behrens
and he listed large cone temps of Orton cones as well. The difference
in the two quotes ranges from 30 degrees F to 40 degrees F. difference.
Nelson lists a temp rise of 270 D F and Beherns lists 108 D.F per hour.
Does this effect the temp the cone finally bends? Just curious, Mike
Gordon
Arnold Howard on wed 9 jul 03
Firing speed during the last 100 - 200°F affects cone bending
temperature. The slower the firing, the lower the temperature. Firing
speed from room temperature up to the last 100 - 200° F of the firing
has little or no effect on cone bending temperature.
Another reason for the discrepancy in cone temperatures between the two
books is that Orton changed some of the temperatures in 1996. This
caused a lot of confusion at the time.
Sincerely,
Arnold Howard
Paragon Industries, L.P.
www.paragonweb.com
From: Mike Gordon
In Glen C. Nelson's book
> he lists Orton cone temps for large and small cones. I wrote these
down
> for future reference. Then I picked up a glaze book by Richard
Behrens
> and he listed large cone temps of Orton cones as well. The difference
> in the two quotes ranges from 30 degrees F to 40 degrees F.
difference.
> Nelson lists a temp rise of 270 D F and Beherns lists 108 D.F per
hour.
> Does this effect the temp the cone finally bends? Just curious, Mike
> Gordon
Ababi on wed 9 jul 03
There is another point. How full is the kiln. Normally my kiln reaches
^6 in 1220C When I fire crystals and the kiln is half empty in 1220C ^7
bends.
Even if you have automatic computed controller like I do it is better to
add cones. It is like the Airplans "Black Box" after the firing you can
learn better where it is hotter and where a little less (very hot)- and
why.
=20
=20
=20
=20
=20
Ababi Sharon
=20
Glaze addict
=20
Kibbutz Shoval Israel
=20
ababisha@shoval.org.il
=20
http://members4.clubphoto.com/ababi306910
=20
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
=20
=20
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Arnold
Howard
Sent: Wednesday, July 09, 2003 8:00 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: cone temps
=20
Firing speed during the last 100 - 200=B0F affects cone bending
temperature. The slower the firing, the lower the temperature. Firing
speed from room temperature up to the last 100 - 200=B0 F of the firing
has little or no effect on cone bending temperature.
=20
Another reason for the discrepancy in cone temperatures between the two
books is that Orton changed some of the temperatures in 1996. This
caused a lot of confusion at the time.
=20
Sincerely,
=20
Arnold Howard
Paragon Industries, L.P.
www.paragonweb.com
=20
=20
From: Mike Gordon
In Glen C. Nelson's book
> he lists Orton cone temps for large and small cones. I wrote these
down
> for future reference. Then I picked up a glaze book by Richard
Behrens
> and he listed large cone temps of Orton cones as well. The difference
> in the two quotes ranges from 30 degrees F to 40 degrees F.
difference.
> Nelson lists a temp rise of 270 D F and Beherns lists 108 D.F per
hour.
> Does this effect the temp the cone finally bends? Just curious, Mike
> Gordon
=20
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Send postings to clayart@lsv.ceramics.org
=20
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Moderator of the list is Mel Jacobson who may be reached at
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Snail Scott on wed 9 jul 03
At 06:17 AM 7/9/03 +0100, you wrote:
>Nelson lists a temp rise of 270 D F and Beherns lists 108 D.F per hour.
>Does this effect the temp the cone finally bends?=20
Yes, it does!
Cones are *NOT* a device for measuring temperature.
What they measure is 'heat-work' - the combined=20
effect of temperature AND time, together. A fast=20
firing may reach, say 1800=BAF, but only have the=20
same effect as a slow firing to 1750=BAF. Time matters;=20
the fusing of ceramic materials is not instantaneous.=20
Since cones are made of ceramic materials, they show=20
a close correlation with what's actually happening to=20
your claywork.=20
While a pyrometer can show real-time variations in=20
temperature, including declines (which cones cannot),=20
it is a less accurate indicator of what is happening=20
to the clay itself than cones are. It's a useful item,=20
but it only shows part of the information you need.
Note that when cone charts list rates of temperature=20
increase, they refer only to the rate of increase=20
during the final stages of firing, when the melt is=20
really happening. The speed of firing hardly affects=20
maturity until then. Earlier, the speed can affect=20
the formation of steam, the burnoff of organics,=20
quartz inversion stresses, etc, but not vitrification.
When Behrens (to use your example) says, 108=BAF/hr,=20
it's only relevant to the last few cones of the=20
firing, so if you want to know the cone of a firing=20
and you've only got a pyrometer (why??), use the=20
chart that most closely reflects the rate of increase=20
toward the end of your firing. If you only have cones,=20
and want to know the temperature of maturity (why??),=20
note how long it takes between cones falling at the=20
end of your firing, figure out the rate of increase=20
from that, and look up the temperature of your final=20
cone on the appropriate chart.
=20
-Snail
John Baymore on thu 10 jul 03
Does this effect the temp the cone finally bends? =
Mike,
Yup.... it does. Coned don;t measure temperature... they measure heat
work. Heat work is a function of the application of heat energy over tim=
e.
So the point at which a cone bends is affected by the rate of climb. Th=
is
"rate of climb" issue is most pronounced by the rate of climb happening a=
t
the end closer to the bending range of the cone.
Orton has a nice little program that you can get for the computer that is=
useful in cone related calculations. Call them.
Also...... some of the "end points" (which is sort of a misleading term
) for some cones have been changed over the past years. So the tables=
in one book and the tables in another book MIGHT be different from THAT
issue too. Older books (60-70's) have the older end points.
best,
......................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086-5812 USA
JBaymore@compuserve.com
http:\\www.JohnBaymore.com
603-654-2752 (studio)
800-900-1110 (studio)
"Earth, Water, and Fire Noborigama Woodfiring Workshop: August 15-24,
2003"
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