revision preference src: Observation of cone bending is used to determine when a kiln has reached a desired state. Small cones or bars can be arranged to mechanically trigger kiln controls when the temperature rises enough for them to deform. <SEP> tgt: Observation of cone bending is used to determine when a kiln has reached a desired state. Additionally, small cones or bars can be arranged to mechanically trigger kiln controls when the temperature rises enough for them to deform.