In response to the widely circulated claim that the Forbidden City in Beijing needs to use 60 tons of pig blood every year to ward off evil spirits, Zhou Gan, a research curator and ancient architecture expert at the Palace Museum, has clarified that pig blood is indeed found in the wooden components of the Forbidden City, but it is not used for exorcism purposes.
The Forbidden City was officially converted into the Palace Museum as early as October 10, 1925.
According to the Beijing Daily, Zhou Gan’s new book, Sitting Under the Eaves of the Forbidden City: Illustrated Answers to Fifty Questions About the Forbidden City, debunks many false rumors about the Forbidden City.
Regarding the rumor that “the Forbidden City uses 60 tons of pig blood every year to ward off evil,” Zhou Gan explained that pig blood is indeed an ingredient in the ground layer of the Forbidden City’s wooden components. However, pig blood is not used to ward off evil, but serves as an adhesive, mixed with lime, tung oil, hemp and other materials to form mortar. This mortar coats the surface of wooden components and protects the wood from sun, rain, and insect damage.
Zhou Gan said that the protein in pig blood breaks down in an alkaline environment and cross-links with calcium ions in the mortar, “which improves the adhesive performance and durability of the ground layer. This is a scientific innovation by ancient craftsmen.”