If a cultural relic is "sick", it can go to the "hospital"! Diseases can also be cured by "combining Chinese and Western medicine"!

Hospital for treating sick cultural relics

——Cultural Relics Protection Laboratory

Text/Li Man and Liu Wenke

Nothing can transcend the cycle of birth, aging, sickness and death. Living animals and plants will bloom and wither over time. Even seemingly lifeless steel and stone will slowly oxidize and weather over time, and finally turn into dust. This naturally includes beautiful cultural relics. According to the "National Survey on Corrosion Losses of Cultural Relics in Museums", among the more than 3,200 state-owned museums in my country, nearly 50.66% of the cultural relics in the museums have varying degrees of corrosion damage, and more than 2.3 million cultural relics in the museums have been severely corroded, accounting for 16.5% of the corroded cultural relics. Cultural relic diseases are a very important issue that plagues cultural relic safety. Copperware seems indestructible, but it is very fragile in the face of disease. For example, if bronzeware suffering from "powdery rust" disease is not effectively treated, it will not only self-destruct, but also quietly corrode a room of precious bronze cultural relics into powder. When murals and other painted cultural relics are unearthed, the colors are bright and the pictures are complete, but they will soon curl, fall off, mold, and become powdery. For example, if mold is not effectively treated, it will corrode the entire mural. Some cultural relics are already in pieces when they are unearthed. It is human nature to cherish beautiful things, and the cherishment of life has led to the emergence of hospitals and doctors. The cherishment of cultural heritage has led to the emergence of cultural relic hospitals and cultural relic doctors - cultural relic protection laboratories and cultural relic protection researchers. In cultural relic hospitals, after being examined by cultural relic doctors, decay can be turned into magic. (Figure 1)

Figure 1 Comparison of the restoration of unearthed artifacts (Source: Henan Provincial Institute of Cultural Relics and Archaeology)

Treating diseases also requires a combination of Chinese and Western medicine

Cultural Relics Protection Technology is a new science developed in recent decades through the cross-disciplinary penetration of multiple disciplines, involving multiple fields such as humanities and social sciences, natural sciences and engineering technology. This discipline is still very young, both in terms of theoretical system and operational technology. This discipline draws on the perfect theoretical framework of other disciplines today to build and enrich its own scientific system, and also actively applies other scientific research technology equipment to the construction of cultural relics protection laboratories. This is just like the introduction of modern analytical testing equipment and technology into medicine more than 100 years ago, just like the introduction of scientific laboratory methods into medicine.

Faced with millions of cultural relics waiting to be "cured", cultural relic hospitals and doctors must have a comprehensive and detailed understanding of the causes of corrosion, decay and damage to cultural relics in order to properly carry out the restoration and protection of cultural relics. There are many reasons for the disease of cultural relics, including environmental factors and human factors. This requires cultural relic doctors to not only use the methods of "looking, smelling, asking and touching" for cultural relics, but also to conduct comprehensive diagnosis and physical examination of cultural relics through modern methods such as "blood tests, X-rays and CT" to find out various diseases in cultural relics.

After finding out the cause of the disease of the cultural relics, the cultural relic doctors must use safe and effective methods to treat the cultural relics. As we all know, as a human cultural heritage, cultural relics are unique and non-renewable in addition to their historical and valuable nature. Faced with these unique items, cultural relic hospitals not only bear the responsibility of treating cultural relic diseases, but also need to ensure the perfect perfection. Traditional Chinese medicine emphasizes the principle of "treating both the symptoms and the root causes", while cultural relic hospitals and cultural relic doctors should treat cultural relic diseases based on the basic principles of maintaining the original appearance, the principle of minimum intervention, the principle of reversibility, aesthetics, and functional restoration according to the different restoration needs of different cultural relics. At the same time, when cultural relics are being treated, they cannot give the healers a completely effective feedback. This puts forward a very high technical requirement for cultural relic hospitals and cultural relic doctors. Not only should they fully examine the diseases of cultural relics, but they should also study the laws of change of the materials made of cultural relics and seek the best technical methods for cultural relic protection. Only by using the modern scientific and technological detection methods of "Western medicine" to find out the root cause and principle of the disease, combined with traditional "Chinese medicine", protection and restoration technology, and formulating reasonable protection and restoration technology plans and process routes for the disease conditions of different cultural relics, can the "sick" cultural relics be perfectly treated. Of course, all of this depends on the specific analysis of the specific case, and should not be generalized.

Restoration Archives: Medical History of Cultural Relics

When the cultural relics that need treatment enter the cultural relics hospital, the cultural relics doctor will create a complete and detailed "medical record" data, which is the restoration file of the cultural relics. In this file, you can find all the "medical history" and "treatment" conditions and effects of the cultural relics. In this medical record of the cultural relics, the medical history and efficacy should be fully recorded through photos, text, and other audio-visual materials, and the conditions before, during and after the restoration of the cultural relics should be presented intuitively. During the restoration process, comparison pictures should also be taken, such as the comparison between the cleaned parts and the uncleaned parts. The data from these medical records will help experts understand the "past medical history" of the cultural relics, see what diseases it had in the past, and how it was repaired. For the archaeological excavation site, as much information as possible should be obtained as soon as possible, and data on the unearthed cultural relics and the burial environment should be collected.

Physical examination equipment: a powerful tool for cultural relics hospitals

After sick cultural relics are "admitted" and archived, they will begin physical examinations. Due to the special nature of cultural relics, it is impossible to use damaging "sampling" or "slicing". Only through some scientific instruments can a comprehensive physical examination of cultural relics be conducted to discover the diseases and potential dangers of cultural relics. Among the physical examination instruments in the cultural relics hospital, some equipment focuses on finding the cause of the disease and determining the symptoms, while others focus on studying the composition of cultural relics, finding the appropriate "blood type" or "same sample", preparing for the restoration of cultural relics, and then completing the rehabilitation treatment of cultural relics. These instruments often observe the field of vision that cannot be observed by the human eye, and obtain more extensive and effective information. These physical examination instruments come in a variety of forms, some of which are well-known, while others are completely unknown, but they play an important role in the restoration of cultural relics.

Figure 2 3D video microscope (Source: Xi'an Cultural Heritage Protection Center)

The three-dimensional video microscope observes and records the three-dimensional morphology of various cultural relics. The fiber optic probe equipped with the instrument can also observe large cultural relics and measure data. The three-dimensional video microscope analysis can observe real-time dynamic images of all sides of the sample in 360° all-round, high-resolution, large depth of field and large working distance. When taking microscopic photos, it can ensure that clear and bright microscopic images are obtained, providing reference materials for disease analysis and later restoration, and has obvious advantages in on-site analysis (Figure 2).

Scanning electron microscope (SEM) can clearly display the surface morphology of rough samples or the microscopic morphology of fracture surfaces with high resolution (3.5nm) and large depth of field, and analyze the causes and mechanisms of fracture. SEM has become an indispensable characterization method in the study of cultural relics. It can achieve non-destructive and convenient testing of micro-region morphology, microstructure, and even chemical composition (Figure 3). Among the collections of the Palace Museum, there is a kind of textile fabric called feather yarn, also called feather yarn. There have been doubts and disputes about the material texture of feather yarn fibers since the Qing Dynasty. Later, representative feather yarn samples were selected and their materials were analyzed. It was concluded that one is 100% wool fabric; the other is a cross-woven fabric with 100% mulberry silk in the warp and 100% wool in the weft. This solved the controversial question of "whether feather yarn is woven from bird feathers" in history.

Figure 3 Scanning electron microscope (Source: University of Science and Technology of China)

Portable X-ray flaw detector (real-time imaging detection system) is a relatively easy-to-understand inspection device. It is based on the same principle as the fluoroscopy in the hospital, and the equipment requirements are basically the same. It must be protected from radiation by a lead room (Figure 4). It can observe the internal structure and preservation status of the object without destroying it through X-rays.

Figure 4 Portable X-ray flaw detector (Source: Internet)

It can explore the production process and degree of disease of some artifacts, reveal the production process characteristics and internal defect distribution characteristics of cultural relics; extract information such as texts and patterns covered or contaminated on the surface of cultural relics; reflect and record the internal details of cultural relics before and after restoration; provide various internal information of cultural relics as a reference for authenticity identification; assist in understanding the development of internal diseases of cultural relics; find difficult-to-open combinations and connection methods; help detect and inspect extracts from archaeological sites, guide cleaning methods; detect and analyze ancient fossils. Using X-ray flaw detectors, many things that are invisible to the naked eye can be found on cultural relics, such as rust spots inside artifacts, such as small cracks on the surface... As the saying goes, a thousand-mile dam collapses because of an ant hole. Timely discovery of small problems on cultural relics can avoid greater losses (Figure 5).

Figure 5, NDT comparison photo (Northwestern University)

The handheld X-ray fluorescence spectrometer is used for non-destructive transmission analysis of cultural relics and quantitative and qualitative analysis of elements, as well as analysis of cultural relics texture and disease: it can be used for fiber observation and component analysis of various cultural relics materials, and to determine the origin of mineral materials. Different modes can be selected for non-destructive testing of cultural relics of various materials, such as the alloy mode can analyze the metal element content in bronzes, the soil or mineral mode can analyze the pigment composition in ceramics and murals, and conduct environmental surveys on archaeological sites.

X-ray diffractometers can perform qualitative and quantitative analysis of various cultural relics and corrosion products, as well as micro-region morphology images and component distribution images, such as rust on metal objects, jade objects, murals, paintings, and crystal materials on ceramics. X-ray diffractometers can analyze the mineral composition information in these sample materials. These devices can be used to conduct preliminary testing before the restoration of cultural relics, and to conduct effect research and evaluation after the restoration. For example, to repair a jade artifact, for the damaged part, we need to use modern jade materials to repair the inlaid part of the ancient cultural relics. The X-ray diffractometer equipment can help analyze whether this material is consistent with the ancient one (Figure 6). Just like the hospital finds the blood type and sample matching that is consistent with the patient through testing, thus completing the restoration of cultural relics. In this matching, there are often some surprising discoveries, just like when Wang Liqin et al. analyzed the pigments of the pottery figurines in Yangling of the Han Dynasty, they found that the cinnabar used in the painted pottery figurines in Yangling was artificially made, proving that artificially made cinnabar had appeared during the reign of Emperor Jing of the Western Han Dynasty (the fourth emperor (157-141)), which was a major breakthrough in the history of chemical process development.

Figure 6 X-ray diffractometer (Source: Internet)

At present, cultural relics protection is developing in the direction of "on-site, in-situ, and non-destructive". The archaeological excavation site has become the first line of timely and effective protection of unearthed cultural relics. At this time, the "ambulance of the cultural relics hospital" - the cultural relics mobile hospital is needed. The role of the mobile hospital is to provide first aid to the cultural relics as soon as possible. In the past, this step could only be completed in the laboratory. The emergence of the cultural relics protection mobile hospital ensures that part of the cultural relics protection work can be completed at the archaeological excavation site. Portable non-destructive analysis instruments and equipment are integrated on the cultural relics protection mobile vehicle, and some optical fiber probes have an unlimited operating range. This has effectively rescued some unearthed cultural relics at the archaeological site that are oxidized quickly and urgently need protection. However, due to the high price, only a few cultural and museum units are equipped with such equipment, such as the State Administration of Cultural Heritage, Shaanxi Provincial Cultural Relics and Archaeology Research Institute, Sichuan Cultural Relics and Archaeology Research Institute, Zhengzhou Cultural Relics and Archaeology Research Institute, etc. (Figure 7).

Figure 7 Cultural Relics Mobile Hospital (Source: Zhengzhou Cultural Relics and Archaeology Research Institute)

The best doctor treats illness before it occurs

The Yellow Emperor's Canon of Internal Medicine puts forward the view that "the best doctor treats the disease before it occurs", that is, a good doctor is one who can prevent disease. Similarly, to be a good "cultural relic doctor", one cannot just stay at the traditional rescue restoration, but also pay attention to the preventive protection of cultural relics. For the human body, regular physical examination is the preventive science of medicine. Preventive protection of cultural relics mainly refers to the effective management, monitoring, evaluation and control of the preservation environment of cultural relics, inhibiting the harmful effects of various environmental factors on cultural relics, striving to keep cultural relics in a stable, clean and safe living environment, and preventing or delaying the changes in the physical and chemical properties of cultural relics and even their final deterioration as much as possible, so as to achieve the purpose of long-term protection and preservation of cultural relics in museums. From rescue protection and restoration, passive maintenance of damaged cultural relics, to preventive regulation of the environment, active maintenance to prevent the deterioration of cultural relics. The principle of preventive protection has become an international consensus and development direction. The number of monitoring centers is increasing, such as the World Cultural Heritage Monitoring Center of the Palace Museum, which has improved the computer network monitoring system that has been established - the "Forbidden City World Cultural Heritage Monitoring Information Platform", to achieve the effect of taking precautions in preventing and controlling the pathology of cultural relics in museums.

This article was originally published in Popular Archaeology, Issue 8, 2014. It has been slightly modified for this publication.