Frederich, Tim on wed 7 may 03
There have been some recent comments about cone temperatures and the charts.
The charts were updated in 1996. Some of the temperatures on the chart were
adjusted, usually in a very small amount, to reflect temperatures obtained
by more accurate temperature measurement. The formulas for cones 4-8 were
adjusted slightly around 1994. The changes that were made would probably
not affect most products or firing profiles. Cone 6 still bends when it
recieves the proper amount of heatwork (the combination of time and
temperature). You still want to rely on the bending angle of the cone to
give you the final heatwork. All cones that we produce have to be within
plus or minus 2 degrees Centigrade of the standard cone which is on record
at the National Bureau of Standards.
The colors that are used in the cones are a water based dye. These dyes can
change slightly from batch to batch so the color may be slightly different
from one box of cones to another. This color is not important to the use of
the cone. The main reason for the color is to improve the production
process by eliminating chance for error. It also allows the customer a
quick method to make sure they have their cones in the proper order.
You can go to www.ortonceramic.com and go to the Center for Firing/Reference
Library to obtain current cone charts in both degrees F and C. Please
contact me if you have further questions.
Orton Ceramic Foundation
6991 Old 3C Highway
Westerville, OH 43082
Phone: 614-895-2663 x 36