The picture shows the experts in the restoration of cultural relics preparing to move the stripped mural fragments to the laboratory for restoration;

  A century of archaeological science and technology ④

  ◎Our reporter Shi Junbin and Fu Xiaobo

  During the new crown pneumonia epidemic, the restoration virtual exhibition of Han Xiu's tomb mural "Xuanwu Tu" was continuously displayed on the official website of Shaanxi Museum, allowing the audience to appreciate the tomb of the prime minister of the Tang Dynasty, Han Xiu, which has a history of more than 1,000 years without leaving home. The mural of "Xuanwu Tu" on the north wall is delicate and flexible.

However, few people know that this precious cultural relic was destroyed by tomb robbers.

The restoration of the cultural relics collected information on the pictures through high-definition scanning equipment and hyperspectral, and spliced ​​the fragments of the murals picked up on the spot. After nearly one year of restoration, the restoration of the murals was finally completed, and thousands of fragments were restored. It is an exquisite mural.

  The tomb of Han Xiu is located in Guozhuang Village, Dazhao Street Office, Chang'an District, Xi'an City, Shaanxi Province.

  According to calculations by archaeologists, this "Xuanwu Tu" is 180 cm wide and 195 cm high. It is by far the largest and most vivid of the Tang Tomb murals in Shaanxi. It has high historical and artistic value.

Xuanwu is a kind of mythological spirit, a combination of turtles and snakes. It is a common subject in the murals of Tang tombs.

  But when archaeologists discovered it, the mural was not only eroded by time, but also maliciously attacked by tomb robbers. A large hole was dug out of a large part of it, and the main picture was destroyed into more than a thousand fragments, which is distressing.

  In order to bring this precious cultural relic back to life, the restoration experts spent a whole year, overcoming a variety of difficulties, and using advanced technical means to complete the restoration of the murals.

The picture shows the true appearance of the mural after restoration.

Photo courtesy of Shaanxi History Museum

  According to Yang Wenzong, a research librarian of the Shaanxi History Museum and deputy director of the key scientific research base of the State Administration of Cultural Heritage and Material Science, after a simple cleaning of the surface diseases of the murals, the cultural relics restoration experts removed the murals little by little and packed them with them. Return to the laboratory for reduction.

  To uncover thousands of fragments of murals of various sizes, thicknesses, and degrees of damage, to piece together into a complete mural is a very brainstorming task.

  The cultural relic restoration experts first perform computer image restoration on the mural, determine the range of the missing area of ​​the picture, then use a pencil to compare the outline of the residual block on the mural supplement material, and then use a cleaning agent to moisten the area and soften it. Then use a scalpel to remove the improper repairs in the middle, and restore the damaged picture bit by bit.

  After the lines are restored, restoration experts use a handheld X-ray fluorescence detection and analysis instrument to detect and analyze the pigment composition on the surface of the mural in order to restore it.

"The main colors of the murals in "Xuanwu Tu" are yellow and orange, and there is a small amount of sky blue in the auspicious clouds. The test results infer that the yellow pigment is mainly lead yellow, the orange red is ocher, and the sky blue is mixed pigment." Yang Wenzong said, according to the results. Inspection and analysis results, restoration experts select the corresponding mineral color pigments for debugging, to ensure that the color of the newly restored part of the mural is harmonious and consistent with other parts.

  From the final restoration mural, you can see that this "Xuanwu Picture" has natural lines, bright colors, skilled painting techniques, and a very high level. The Xuanwu's facial expressions in the picture are vivid and the posture is lifelike.

  Yang Wenzong said that the restoration of "Xuanwu Tu" highlights the new concept of mural restoration in my country in recent years, that is, to distinguish the original state of the original cultural relics and the acquired destruction in the restoration, which not only reflects the archaeological value but also takes into account the artistic value.

Rebirth of cultural relics through sophisticated scientific and technological means is the mission of cultural relics protection workers, and it is a task full of challenges, demonstrating the craftsmanship of cultural relics protection workers.