Occasionally we are asked what causes the Kiln Sitter to overfire.
The most common causes:
1) The trigger out of adjustment
2) A corroded tube
3) A bent rod
4) An obstruction outside the kiln preventing the weight from dropping
5) Ceramic ware falling against the actuating rod
6) A cone sticking to the cone holder. (This is why you should coat the cone supports and actuating rod with kiln wash.)
Always monitor the kiln, even though you have an automatic shut-off. The Kiln Sitter, or any other shut-off device, can fail. Nothing can replace the attention of the operator. Automatic shut-off devices are designed for convenience, relieving you from having to closely watch the kiln. But no shut-off was ever meant to eliminate the monitoring of the kiln.
Good luck with your firings!
Arnold Howard Paragon Industries, Inc.