Test Firing With Witness Cones; Cone-Fire - How It Works - Orton AutoFire AF4TS User Manual

Test Firing with Witness Cones

A test firing will help in learning the operation and features of the controller. Follow your kiln manufacturer's
instructions for setting up your kiln.
Place a series of Orton Self-Supporting Cones on the middle shelf of your kiln so that they can be seen through a
kiln peephole. Use a series of cones close to the final firing temperature (see Appendix C). For example, if firing to
1945°F (Cone 04), use a Cone 03, Cone 04, and Cone 05 for the test firing.
To evaluate heat distribution, place a set of cones on each shelf during the test firing. Most kilns fire more
uniformly at Cone 06 than they do below Cone 06. Provide ventilation for the kiln in accordance with the kiln
®
manual or VentMaster instruction manual.
After the firing, examine the fired cones. Some variation in the bending of the cones may occur, depending on how
the kiln was loaded and the location of the cones.
Cone-Fire – How it works
When firing to a cone number, the controller constantly monitors the actual heating rate of the kiln. If the kiln
does not fire as rapidly as programmed, the controller re-calculates and adjusts the top firing temperature to
compensate for the slower firing rate. This process more accurately fires to the cone number selected. When the
heating rate slows, cones deform at slightly lower temperatures. At faster heating rates, cones deform at slightly
higher temperatures. This ability to recalculate and to fire to a cone value is a unique, patented feature of all Orton
controllers.
Orton Controllers contain three preset program groups for firing to a cone number – Low Fire, Mid Fire, and High
Fire. Each of the programs can be adjusted for speed, hold time and cooling rate. The standard programs are
designed to fire normal loads of thin ware ceramics. When a kiln is more heavily loaded or when thick ware is
fired, additional firing time is needed. Experiment to determine the best firing conditions. The preset firing
programs in the controller are:
Program Product Fired
Low Fire Decal, Luster, China
Mid Fire Glaze, Bisque, Earthenware
High Fire Stoneware, Porcelain
LO FIRE PROGRAM
0 100 200
TIME
AutoFire Slide Kiln Controller
Cone Range
Cones 022 – 011
Cones 010 - 01
Cones 1 – 12
MID FIRE PROGRAM
0 200 400
TIME
7
Firing Time
3 - 5 hours
6 - 8 hours
9 - 11 hours
HI FIRE PROGRAM
0 200 400
T IME
600