The firing of the green tiles is primarily divided into three stages: the early, middle, and late firing stages.

During the Qingwa firing stage, it is necessary to drain water from the kiln cave and raise the temperature in all areas of the brick kiln to the same level.

2. The intermediate stage of the green tile firing process is a gradual warming-up of the unglazed bricks.

As the firing of the blue tiles progresses and most of the chemical changes in the earthen bricks are completed, the high temperature is maintained continuously, resulting in the stable formation of the blue tiles through a series of physical transformations.

4. During the late stage of firing, the gases emitted from the kiln's top outlet are light gray-black, laden with a substantial amount of carbon black. The carbon black reduces the formed ferric oxide to black ferrous oxide (FeO), while the remaining carbon atoms slowly infiltrate the gaps between clay particles at high temperatures, eventually turning into the blue color of the glazed tiles.