What material is used instead of glass for the windows of Gongwangfu in Beijing?

Now the windows of Gongwangfu are all made of glass, but it was not until the Qing Dynasty and after Yongzheng that there were glass windows for the first time. The glass on the windows of the Forbidden City replaced paper in a large area, which should be between the end of the Qing Dynasty and 1949.

The doors and windows of Gongwangfu connect the external and internal space of its building, which has both practical function and aesthetic value. At the same time, the decorative patterns of doors and windows of Gongwangfu also reflect its different hierarchical system, which has rich development and changes. Through on-the-spot investigation, sorting out data, drawing related patterns, analyzing the types of doors and windows and the characteristics of their decorative patterns, and exploring the cultural and artistic connotation of their decorative patterns. With the emphasis on cultural inheritance in recent years, studying the decorative patterns of doors and windows of Gongwangfu is helpful to promote the inheritance and development of traditional culture.