If cones are exposed to moisture during their life, they may crack and bend prematurely when fired.
If you have problems with cracked cones because they become damp, drying them will not correct the damage. Use another box. Always store cones in a dry place.
Cones are slender pyramids composed of ceramic materials used to determine the combined effect of temperature and time, which is sometimes called ‘heat-work'.
Clays and glazes are fired to different points referred to by their cone equivalent or number.
Pieces that are heavily glazed should be kept further apart during firing to avoid glaze running from one piece to another.
You cannot use a clock to time your firing instead of a cone. Many kilns are equipped with limit timers that will shut them off to prevent over-firing but time does not control accurate firing.
A pyrometer indicates when it is time to start watching the cone in kilns without automatic kiln sitters. It is not a substitute for a cone
The observation holes of the kiln allow viewing of the firing chamber and pyrometric cones. They also provide an escape for water vapor and gasses.
|Jennifer Mathes, Ph.D.|