If silk products have been degraded, turned into ash, and ground into mud over a long period of time, can archaeologists still determine what they are?
The answer is – as long as silk is not completely decomposed into chemical elements such as carbon, nitrogen, oxygen, and hydrogen, it can!
With the immunoassay method pioneered by the China Silk Museum, archaeologists have successfully detected the trace of silk fibroin in the soil of the Yangshao Culture and Longshan culture tombs at the Yangshao Village site, indicating that there may have been silk objects in the tombs. In the sacrificial pit of Sanxingdui, the same method was used to prove that silk products were burned during the sacrificial ceremony.
Silk, for other archaeological institutions, is just one branch of numerous research fields. But for the Chinese Silk Museum, it is the top priority of their research. They have a unique skill in searching for and restoring silk artifacts. When traditional methods are at a loss, they immediately disperse the clouds and mist.
Extract the silk fibroin needle from the “ocean” of leftover materials
The China Silk Museum is the supporting unit of the key scientific research base of the National Cutural Heritage Administration for the protection of textile cultural relics. Finding the origin of silk is an important academic topic for them.
Since 2012, the China Silk Museum has collaborated with universities such as Zhejiang University and Zhejiang University of Science and Technology to complete a series of research projects on silk micro mark detection based on immunological principles.
This technology is suitable for samples with very severe degradation, such as silk that has been mudded, carbonized, ashed, or mineralized and separated from the physical substance of textiles. When traditional methods are at a loss, immunoassay can be highly effective.
Zhou Yang, deputy curator of the China Silk Museum and director of the key scientific research base of the National Cutural Heritage Administration for the protection of textile relics, told the Science and Technology Daily that immunoassay relies on the immune response of antigens and antibodies.
The key to this technology is to find molecular markers of silk and prepare antibodies.
Silk fibroin is a natural polymer protein composed of 18 amino acids connected in a specific sequence.
The determination of molecular markers benefits from researchers’ understanding of the micro molecular level of silk fibroin.
Preparing antibodies is not always a one-time success. Researchers need to extract antibodies from animal serum through animal immunity. Due to the involvement of animal husbandry, it is difficult to ensure the consistency and stability of this process. If the antibody titer is not good, you need to start over again.
The advantage of immunoassay is that it is very precise, and it is also very sensitive. Even if the sample is particularly complex and the concentration of silk fibroin is extremely low, as long as it is not completely decomposed, it will generate an immune response. Immunoassay can discover silk fibroin as a ‘needle’ in the ‘sea’ composed of numerous remains at archaeological sites, “Zhou Yang said. In addition, it can also determine the biological species of silk, whether it is mulberry silk or wild silk. As long as there are relevant customized antibodies, it can be further classified.
Even if silk turns into mud, immunoassay can still recognize it
This technology is original in China, with over 30 invention patents and independent intellectual property rights. Previously, the “Research and Application of Key Techniques for Immune Detection of Textile (Silk, Wool) Cultural Relics in Archaeological Sites” of the China Silk Museum was identified by experts and deemed to have reached an international leading level.
Our goal is to expand the temporal and spatial scope of silk archaeology and search for the origin of silk, “said Zhou Yang. Technology reveals information that may be overlooked at the first archaeological site, extending archaeology from the visible material level to the invisible molecular level.
Why search for the origin of silk? Zhou Yang said that others have also asked her this question many times.
For Chinese civilization, the initial origin of silk was in mythological stories, where Emperor Huang’s Yuan consort, Lei Zu, taught people to breed mulberry and raise silkworms. Silk has always accompanied Chinese civilization, never being late or leaving early, and has also traveled along the Silk Road to the world. On a material level, it is a globalized trade commodity; At the spiritual level, it is a cultural symbol. Silk is so important, where is its origin? Does it originate in China? Can the original contribution of the Chinese people to the world be conclusively proven? To answer these questions, we need to rely on archaeological evidence, “Zhou Yang said.
Last year, researchers from the China Silk Museum discovered remnants of mulberry silk from over 5000 years ago in the urn coffins unearthed at the Wanggou Site in Henan Province, which is also the earliest silk object discovered in the world.
Immune analysis not only traced the roots of silk, but also helped Nanhai 1 find the “hidden” goods.
Now when searching online for Nanhai No.1, one can still see a question from a certain Q&A website: Why doesn’t Nanhai No.1 have silk?
Someone answered, ‘There should be, silk fibroin has been detected in the hull mud.’.
This’ legitimate name ‘was also created by the Zhou Yang team.
They found silk in the sediment at the bottom of the No. 10 compartment of the South China Sea No.1 sunken ship using immunoassay.
Nanhai No.1 was a sunken ship during the Southern Song Dynasty, loaded with popular export commodities such as ceramics, metalware, and lacquerware. It is an important material material and precious underwater cultural heritage of the Maritime Silk Road trade.
However, since it is a trade ship sailing on the Maritime Silk Road, is there any silk on board?
When the team went to sample, they were facing an empty cabin with only some mud at the bottom. It was from the mud that they detected a strong signal of silk fibroin. This now empty cabin may have been filled with silk.
“At that time, I was really happy. We did a meaningful thing, which shows that the Maritime Silk Road is silk!” Zhou Yang’s tone jumped when he mentioned this matter.
Fix Silk with Silk to Treat the “Cancer” of Silk Cultural Relics
Another great feat of the China Silk Museum is to restore silk fabrics, turn decay into magic, and bring silk artifacts back to life.
This stunt is called silk fibroin grafting reinforcement technology. The application object of technology is high-strength silk, that is, silk that can easily break at a touch.
Decadent, known as the cancer of silk artifacts. Some silk relics have been buried for too long, and most of the chemical bond of amino acids have been broken, which will become extremely fragile. But we are a key research base for the protection of textile cultural relics, and the more difficult the problem, the more we need to overcome it, “Zhou Yang said.
So, can we reconnect the broken chemical bond at the microscopic level?
The research team of the China Silk Museum and Zhejiang University of Technology have collaborated to develop a silk fibroin grafting reinforcement method, which involves placing small molecule silk fibroin fragments into decayed silk artifacts.
To put it bluntly, it is homologous reinforcement, using silk to fix the silk. “Zhou Yang said that the repair material and the repaired object have homology, which is conducive to avoiding the” adverse reactions “that occur after chemical methods of repair.
When repairing, the workers need to find suitable materials to ensure that the silk fibroin fragments can be added and stuck together to form new chemical bond.
Zhou Yang made an analogy, for example, there is now a dilapidated house with cracks between the bricks, revealing gaps. To repair it, you need to figure out how big the gap is and which type of cement to use. The silk fibroin fragment is of the right size and can grow in the gap.
Every silk artifact that suffers from decay and disease is a terminally ill patient. Various checks must be conducted first to understand the basic data; Then experts will consult and customize a treatment plan for it; The plan has been determined and the medication has been prepared before entering clinical surgery.
Zhou Yang said that they adhere to the principle of minimum intervention and do not easily use this method unless it is necessary.
The China Silk Museum has restored a Southern Song Dynasty purple brown ribbed gold colored lace single garment, which is 800 years old.
With this reinforcement technique, they successfully “awakened” this Southern Song silk dress. The single garment has gone from fragile and decadent to soft again, and now it can be exhibited, telling the audience about the owner’s life 800 years ago.
The importance of technology in the field of cultural relics protection cannot be overemphasized. After working in the field of textile cultural relics protection and research for nearly 30 years, Zhou Yang sighed that many technologies have undergone more than ten years of polishing before they can be applied. She stated that it is necessary to continue to strengthen research on basic theories and key scientific issues related to the protection and utilization of cultural relics, in order to generate new technologies, equipment, and materials.
Reporter Zhang Gelun