Why can't Cheng Niyan cook?

The surface is coated with beeswax. Cheng Ni inkstone can't be boiled, because there is a beeswax coating on the surface, and boiling water will destroy the beeswax coating. Cheng Ni inkstone is one of the traditional Chinese handicrafts and calligraphy tools. It started in the Han Dynasty, flourished in the Tang and Song Dynasties, and has a history of more than 1000 years. Since the Tang Dynasty, Duanyan, She Yan, Taohe and Cheng Ni have been called "four famous inkstones".