Orton is THE top producer of pyrometric cones! Anyone who has spent time firing kilns knows that Orton pyrometric cones are essential tools for obtaining reproducible results during firings.
So how, exactly, do these Orton cones work? Cones are composed of carefully-formulated compositions of ceramic materials. Each cone type is assigned a number (for example, cone 06), and this number denotes a specific and fairly narrow temperature range (for example, cone 06 indicates a temperature range of approximately 1800 - 1850F).
During firings, cones are placed within the kiln, usually in a cone holder or a block of clay, and as the temperature increases, Orton pyrometric cones absorb heat. As the cone reaches the temperature that it is formulated to melt at, the tip of the cone begins to bend. It is recommended that you use 3 cones in your firing: one cone that will mature at the temperature you wish to achieve, one cone right below this temperature and one above. This will help you achieve accuracy in your temperature measurements. Because different cones require specific temperatures to mature, they will bend at different temperatures from each other, enabling you to determine how hot your kiln has gotten and whether you have reached your desired temperature. If you are firing a relatively large kiln or a kiln that you know has a temperature differential, it may be useful to place cones in different spots within the kiln, to determine whether you kiln was evenly heated.
Orton Large Pyrometric Cones measure approximately 2.5" tall. Cones come packaged in a box of 50.