The Bending of a Pyrometric Witness Cone
Pyrometric cones measure heat work in ceramic kilns. The cones are small pyramids of clay and mineral oxide that soften and bend when exposed to heat. Twenty years ago glass artists used cones too. Now most of them use digital controllers.
Standard large cones must be mounted in a clay or wire plaque with 2” of the cone exposed above the cone holder. Self-supporting cones stand upright without holders. We recommend self-supporting cones. They are easier to use than standard large cones.
The standard large cone, when fired to maturity, bends straight down toward the kiln shelf. This is called the 6 o’clock position. It is okay if the tip of the cone touches the kiln shelf.
On the other hand, the self-supporting cone, when fired to maturity, bends downward until the tip is even with the top of the base. If the self-supporting cone tip touches the kiln shelf, the cone is over-fired by a few degrees.
With best wishes,
Arnold Howard Paragon Industries, L.P. - Better Designed Kilns 2011 South Town East Blvd. Mesquite, TX 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 firstname.lastname@example.org / www.paragonweb.com