In the laboratory, the furnace temperature and stopwatch are used to control the firing temperature and time of the enamel products. After the furnace is released, the gloss or adhesion strength of the products can be checked with instruments to determine whether the firing degree is appropriate.

In production, when firing in a batch-type muffle furnace, it is mainly to use visual inspection and experience to determine whether the enamel product can be out of the furnace after firing. When the dry powder billet is put into the furnace, the powder billet appears very dark in contrast to the bright red furnace wall. As the temperature rises, the billet body begins to change color and gradually shows the light and color similar to the furnace wall. At this time, the temperature of the green body is close to the temperature of the furnace wall, but the temperature of the inner layer of the iron billet may be slightly lower, and it will take a while to be out of the furnace. How long this period of time depends on the wall thickness of the blank to determine, the operator's experience in this area is very important.

The firing of the continuous enamel firing furnace is adjusted by setting the furnace temperature gauge and the linear speed of the transmission chain (or the rotation speed of the driving wheel), and the temperature and speed are determined by the on-site technical supervisor for product adhesion, porcelain surface gloss and smoothness. It is determined after the first inspection.