Orton manufactures four different types of cones (Small cones, Bar cones, Large cones and Self- supporting cones).

The Large and Self-supporting cones are used to measure temperature uniformity and/or if there was sufficient heatwork done to mature the ware. Cones indicate whether the ware received an adequate amount of heatwork to properly mature the clay or glaze. A properly fired cone will bend over with the tip of the cone almost touching the shelf. After firing a kiln, a simple glance at the cone can tell if the firing was successful.

The small and bar cones are mainly used in the kiln shut-off device called the Kilnsitter. This ia mechanical device that shuts off the kiln when the temperature inside is sufficient to cause the cone to deform under the weight of the Kilnsitter rod.

The only true measurement of heatwork is from a Large or Self- supporting cone placed on the shelf next to the ware.

Frequently Asked Questions about cones can be found on Orton website.

Resources may also be found on the Orton website

Large Cones

Large Pyrometric Cones allow users a practical method to monitor the heatwork (the effect of temperature and time at temperature) inside their kiln. Today they are used by quality conscious manufacturers who want a visual indication of the heatwork in locations throughout their kiln.

Large cones must be mounted in a plaque with the cones mounted at 8 angular degrees. Plaques can be made by hand or purchased through Orton.

Cone numbers 12 and higher are also available as PCE cones.

In 2016, Orton began packaging Small cones in pairs like Large and Self-Supporting cones. We made the change to reduce the number of cones broken during shipping.

​Downloadable PDFs

• Safety Data Sheets (SDS)
• Cone Chart
• Cones & Firing Brochure