Pyrometric cones constitute a ready to use and reliable means of checking an ovens temperature. In fact they are used in almost all sectors of the ceramics industry.

The cones don't substitute the thermocouples, in measuring the temperature. They are quite useful for calibrating measuring instrument, and measuring temperatures reached in different parts of an oven.

Three consecutive cones an normally used, the middle one corresponding to the desired temperature. The cone which tip reaches the base represents the exact  temperature the system encountered during the firing process.

It is wise to attach the cones with some clay and let dry before putting in the oven so as not to allow humidity to affect their performance, furthermore it is important to avoid placing them in contact with the burners, or in cold spots.