Pyrometric Cones

Abstract

Pyrometric cones have been used as temperature indicators and are still used as end-point indicators in such batch processes as firing in pottery furnaces. They can be small, expendable, plugs, chips, or geometrically shaped objects whose purpose is to accompany the products through a heating cycle. The German ceramist Herman Seger invented the first pyrometric cone in 1886. Because the pyrometric cone measures the effects of both temperature and the length of firing time, it acts as a heat integrator, a function that cannot be easily reproduced by thermocouple-type pyrometers. While pyrometer cones are not well suited to automatic process control, they are inexpensive and valuable quality control tools in guaranteeing repeatable qualities of ceramic and similar batch products from kilns and furnaces.