Why do Dunhuang frescoes change color
When people wander in the art palace of Mogao Grottoes in Dunhuang, they are often overwhelmed by its exquisite and gorgeous murals. In fact, the colors of the existing murals are different from when they were first painted, and the skin color of the characters has changed.
Wu Rongjian, a librarian from the Fine Arts Institute of the Dunhuang Academy who has long been engaged in the copying and research of the Mogao Grottoes murals, said that from the research results, the discoloration of the Dunhuang murals is mainly the skin color of the characters and the colors similar to the pigment composition. The flesh color has changed to black, lead gray or brown.
Cause of discoloration
In the past, many experts believed that the discoloration of the Dunhuang murals was caused by the use of lead powder in the paint when the ancients painted. The lead powder was oxidized, which caused the murals to change color. However, new scientific analysis shows that the skin color and similar color of the figures in the Dunhuang murals In, lead powder is not used.
Not long ago, researchers from the Dunhuang Academy conducted X-ray diffraction analysis on a sample of the figure painting pigments in the murals, and found that the discoloration of the Dunhuang murals has an important relationship with three factors: the first is the use of Zhu Dan and the blending colors containing Zhu Dan.
After thousands of years of oxidation reaction, the color of the original painting has been completely changed; the second is that the plant pigments fade directly after thousands of years of oxidation, or are overturned by the changing colors of the lower layer; the third is that the Dunhuang soil is a seabed that has been soaked in seawater. , Contains a large amount of basic elements and becomes a catalyst for the chemical reaction of pigments.