The specific gravity of zinc oxide after high-temperature calcination (calcination temperature at 1250 degrees Celsius, Xinfengrun firing curve) will increase to 2.0 to 2.5. The use of glaze in the glaze is good, no thixotropic, no pinhole, can increase the speed of the kiln High yield bricks. Zinc oxide that is not calcined or whose calcining temperature is not enough and whose specific gravity is not enough will affect the process performance of the glaze and reduce the production stability.