David Woodin on tue 9 jan 01
The newer Orton Tables say the ramp is for the last 90 to 120 minutes.
Therefore cone 10 would bend at 2281 for self supporting or 2377 for regular
cones at a ramp of 270 deg per hour. Cone 9 @ 270 ramp selfsupporting cone
2336, regular 2332. But most kilns won't go that fast and we are probably
more interested in ramps less that what the tables are made for. You can
come quite close by using data for self supporting cones and draw your own
graph using the published information for 27 deg/hr, 108 deg/ hr and 270
deg/hr. In that case cone 10 could bend at 2311 at a ramp of 50 deg/hr. or
cone 9, 2263 at a ramp of 50deg/hr.
David
Joyce Lee on wed 10 jan 01
ok
David Woodin wrote:
>
> The newer Orton Tables say the ramp is for the last 90 to 120 minutes.
> Therefore cone 10 would bend at 2281 for self supporting or 2377 for regular
> cones at a ramp of 270 deg per hour. Cone 9 @ 270 ramp selfsupporting cone
> 2336, regular 2332. But most kilns won't go that fast and we are probably
> more interested in ramps less that what the tables are made for. You can
> come quite close by using data for self supporting cones and draw your own
> graph using the published information for 27 deg/hr, 108 deg/ hr and 270
> deg/hr. In that case cone 10 could bend at 2311 at a ramp of 50 deg/hr. or
> cone 9, 2263 at a ramp of 50deg/hr.
> David
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Frederich, Tim on wed 10 jan 01
David,
You are correct in the fact that we base the equivalent temperature on the
heating rates for the last 90 to 120 minutes of firing. I would reccomend
that people look at the numbers under the 108 degree heating rate column.
This is much closer to what normal kilns can achieve and is the heating rate
that most kiln controllers base their automatic programs on. As a rule of
thumb, the slower the heating rate the lower the equivalent temperature of a
particular cone will be. This is why the time and temperature relationship
called heatwork is important to consider when designing and using a firing
schedule. As more people use kilns with controllers on them, it is important
to keep using cones to calibrate the controller and to insure that the clay
and glazes are recieving the proper amount of heatwork required. If anyone
has questions about cones and how to interpret the bending angle and
equivalent temperature reached please contact me at the Orton Ceramic
Foundation. My number is 614-895-2663 ext.36. I will also present a program
on cones and kiln monitoring at NCECA during the Equipment Doctors segment.
Best regards,
Tim Frederich
-----Original Message-----
From: David Woodin [mailto:DWoodin521@AOL.COM]
Sent: Tuesday, January 09, 2001 11:23 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Kilns, Firing technology
The newer Orton Tables say the ramp is for the last 90 to 120 minutes.
Therefore cone 10 would bend at 2281 for self supporting or 2377 for
regular
cones at a ramp of 270 deg per hour. Cone 9 @ 270 ramp selfsupporting cone
2336, regular 2332. But most kilns won't go that fast and we are probably
more interested in ramps less that what the tables are made for. You can
come quite close by using data for self supporting cones and draw your own
graph using the published information for 27 deg/hr, 108 deg/ hr and 270
deg/hr. In that case cone 10 could bend at 2311 at a ramp of 50 deg/hr. or
cone 9, 2263 at a ramp of 50deg/hr.
David
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
| |
|
