What is the putty made of ground mortar?

Ground warfare is a traditional civil engineering technology in China, that is, covering a wooden structure with a base material to prevent corrosion and moisture. For the sake of beauty, it is usually painted with oil.

This practice was formed in the Ming Dynasty, and it is said that it gradually evolved from the lining of architectural oil painting projects in the Tang and Song Dynasties. The coating and dry coating used are also called ground warfare,

It is made of fermented animal blood, tung oil, flour, brick ash, etc. When it is used, it is scraped and coated on the surface of the wood structure in layers. In order to prevent the coating from cracking and peeling off and enhance the tension of ground combat, it is usually reinforced by covering linen in the scraping and coating process.

Large buildings have strict requirements for ground warfare projects, such as the ground warfare in the Forbidden City in Beijing, which is called "two hemp and six ashes".