| ■Tokyo National Research
Institute for Cultural Properties |
■Center for Conservation
Science |
| ■Department of Art Research,
Archives and Information Systems |
■Japan Center for
International Cooperation in Conservation |
| ■Department of Intangible
Cultural Heritage |
|
Visiting the Analytical Science Section
Lecture on conservation of Modern Cultural Heritage
The Tokyo National Research Institute for Cultural Properties (TOBUNKEN) held the “2022 Training for Museum Curators in Charge of Conservation (Advanced Course)” for five days, from July 4 to July 8, 2022.
This training is an application version of the trainings for museum curators in charge of conservation, which were held from 1984 to 2020 for curators in charge of material conservation to master basic knowledge and techniques necessary for environmental management, evaluation, and improvement.
From 2021, we reorganized the training into two courses: 1) basic course, focusing on conservation of environment by the National Center for the Promotion of Cultural Properties, and 2) advanced course, focusing on curators who attended the course before and/or who have similar experiences, by TOBUNKEN.
We provided lectures and workshops mainly based on research outcomes of each research area of the Center for Conservation Science, along with lectures from external lecturers related to various conservation and restoration in the advanced course. We are pleased to have organized face-to-face training with 18 participants, with thorough prevention measures for COVID-19 pandemic. We believe that the participants made their networks there.
Based on questionnaires after the training, we understand that the participants were well satisfied. We could know their voices: “I will try various techniques from this training in our museum,” “I could review my understandings and obtain new knowledges. It was very beneficial for me,” and “It was a very useful week for me.” Henceforth, we will work to provide more useful training to curators in charge of conservation.
Video and photo documentation of the chisel manufacturing process
Manufacturing chisels for sculpture
Understanding the manufacturing situation of tools and raw materials used for restoration is extremely important to continue sustainably restoring cultural properties. However, “the Research Project on Preservation and Restoration of Tools and Raw Materials,” commissioned to the Tokyo National Research Institute for Cultural Properties (TOBUNKEN) by the Agency for Cultural Affairs since FY2018 revealed that the manufacture of tools and raw materials for cultural property restoration faces many challenges rooted in the following two factors. The first is the human factors of aging manufacturers and a shortage of successors, and the second is factors caused by shifts in social structures, such as deteriorating business and the unavailability of raw materials. Considering this research outcome, the Center for Conservation Science initiated a project to collect fundamental physical property data and to document tools and raw materials necessary to preserve and restore cultural properties. The Center has worked on this project with the Department of Art Research, Archives and Information Systems and the Department of Intangible Cultural Heritage. This monthly report presents the documentation survey of chisels for sculpture, the manufacture of which will cease.
Chisels and saws are key tools to restore wood carving cultural properties because new timber materials may be carved and used as repair materials. Konobu Ltd. (Konobu), founded in the early Shōwa era (early 20th century) by the Takiguchi family, specialized as carving tool smiths. Since then, this smith has manufactured chisels for sculpture; Mr. SAITO Kazuyoshi succeeded their manufacturing techniques. Their products have been favored by many in charge of wood carving restoration and wood carving itself. However, Konobu stopped accepting new orders in October 2021 and expressed that they would soon close their business. TOBUNKEN used videos and photographs to document their full manufacturing process of chisels for sculpture, as well as their equipment and smith tools in interviews from May 23rd to 27th, 2022. Mr. KADOWAKI Yutaka of BIJYUTSUIN Laboratory for Conservation of National Treasures of Japan and the Agency for Cultural Affairs cooperated in this documentation survey.
Unfortunately, it became almost impossible to experience and observe in person the Konobu chisel manufacturing process. We plan to organize the survey records to serve as a clue for future generations who want to reproduce chisels for sculpture.
Presentation by HAYAKAWA Noriko
HAYAKAWA Noriko of the Center for Conservation Science spoke about the relationship between techniques and materials for cultural property restoration in Japan titled The Relationship Between Traditional Painting Materials and Techniques in Japan from a Scientific Perspective in a talk at the symposium held in Bard Hall, New York City, United States, on May 6th and 7th 2022.
This symposium titled Conservation Thinking in Japan and India was held both in person and online by Bard Graduate Center with support from the Andrew W. Mellon Foundation. There, experts on restoration of Japanese cultural properties and fine art history introduced their latest research from Japan and other countries.
HAYAKAWA introduced two primary points among research in the Restoration Materials Section: the fact that furunori (aged paste) used for restoration of paintings is corelated to fringe materials and techniques, and an assumption that changes in the manufacturing process for silk, a support material of paintings, altered its string forms and preservability, which then impacted painting expression.
Tours around related facilities and other meetings were held before and after the symposium, where useful discussions were conducted based on actual restoration cases.
Scientific elucidation of materials and techniques is required even during everyday operations in restoration and material production. Opinion exchanges with other experts triggered further research. This presentation was a precious opportunity to disseminate our research outcomes to a wider audience.
Seminar in the meeting room
A series of seminar on the survey and management of conservation environment is organized annually, targeting the curators in charge of conservation for materials in museums and researchers engaged in conservation of cultural properties. These seminars aim to share common understanding on the surveys, assessment methods and improvement of conservation environment, and materials and tools for safe storage. The first and second seminars were organized by the National Center for the Promotion of Cultural Properties (CPCP) and the third was held with a co-sponsorship of CPCP and the Tokyo National Research Institute for Cultural Properties (TOBUNKEN.)
In the first seminar, titled the Survey and Assessment of Air Environment Using Kitagawa Detection Tubes, usage and appropriate assessment methods of Kitagawa detection tubes, which were widely used for quantitative analysis of chemicals in the air in the exhibition and storage rooms, were explained. In the second seminar, titled Neutral Papers as Materials Used for Document Conservation, the scientific character of paper, characteristics and standards of neutral paper, and appropriate usages of conservation containers made of neutral paper were explained with hands-on practice. Neutral paper is widely used as a material to create document conservation containers in storage and stack rooms.
The theme of the third seminar was chemical substance absorbent. Recently, concerns about chemical substance emission from the building and interior materials and its impact on the documents, as well as methods to improve the situation have attracted people’s attention. However, we are still exploring the best possible ways to clean the air in exhibition and storage rooms. Therefore, we invite a company that develops chemical substance absorbent to explain methods of selecting appropriate chemical substance absorbent, as well as the adsorption phenomena, principle and structure of absorbent, and environmental factors related to adsorption efficiency.
We conducted this seminar with eight participants in person and distributed it online for the prevention of the spread of COVID-19 infection. A total of 30 people participated in the seminar. Participants provided their opinions on the usefulness of the seminar because they could learn from the principle to the practice, stating, “I could well understand the types and mechanisms of gas adsorption,” and “as I understood the principle of gas adsorption and measurement methods, it would get easier to assume the solutions.”
We plan to continue the seminars by setting themes that are necessary for daily practices, from the viewpoint of conservation science.
Preparation for the survey
Discussion about the investigation parts
Department of Art Research, Archives and Information Systems has been engaged in a series of surveys on Rakan-zu (a painting of Arhat, an enlightened Buddhist high priest) painted in the Yuan Dynasty, owned by the Baijōsan Kōmyōji Temple in Minato Ward, Tokyo. Please refer to our online monthly report for this survey. (https://www.tobunken.go.jp/materials/ekatudo/910616.html)
Near-infrared imaging and fluorescence imaging produced by optical survey suggested that the new artificial iwa-enogu (mineral pigment used in paintings) could have been used to add colors on several parts of this painting.
It is expected that, in addition to the observation on the imaging data including high-definition imaging, scientific analysis survey can provide additional data from the different approaches. Then, we, INUZUKA Masahide, CHI Chih lien, TAKAHASHI Yoshihisa from the Center for Conservation Science, and EMURA Tomoko, YASUNAGA Takuyo and MAIZAWA Rei from the Department of Art Research, Archives and Information System conducted a survey on Rakan-zu by reflectance spectrometry at the Baijōsan Kōmyōji Temple on January 19th, 2022.
Reflectance spectrometry can identify the kinds of coloring materials used in the work by reflectance spectrometry formation, how the reflectance of the surface against wavelength of light. Furthermore, hyperspectral camera, which we used this survey, shows the distribution of the same reflectance spectra in two dimensions simultaneously.
We plan to identify the materials and places for adding color by analyzing the data which we have gathered in this survey.
Method to identify cultural property pests using DNA as an identifier
Collecting frass from buildings
Damages caused by cultural property pests are a serious and global threat to cultural property conservation because they result in significant losses of cultural property materials and largely reduce their values. Thus, it is critical to identify and take appropriate measures as soon as the cultural properties start showing signs of damage to prevent further loss. However, we may encounter a situation in which it is difficult to identify “criminal” species even by experts, as we cannot find living insect pests but only their frass. To overcome these difficulties, the Biological Science Section has identified cultural property pests using DNA extracted from frass as an identifier.
As the outcomes in FY2021, we succeeded in establishing a method to identify species by frass for the major pests boring bamboo, which are used as part of cultural property buildings and to create craft works. The method includes collecting bamboo-boring pests, extracting the DNAs, and determining a short section of sequence from a specific gene. The datum is registered in the international databases, combining the morphological characteristics and the DNA sequence. Then, DNA is extracted from frass collected at rearing containers and outside buildings, determining their target sequence. The resulting sequences are compared to the reference databases to find the matching species. Before the establishment of the method, it was difficult to determine the base sequence, because the DNA extracted from the frass was either too small or contaminated by DNA of other species. However, specific primers for PCR constructed in this study enabled us to succeed in identifying “criminal” species using anonymous frass collected in the cultural property buildings, rather than being limited to laboratories. Please refer to “Science for Conservation” #61 for further details.
In the future, we plan to further develop specific primers to identify species by frass of cultural property pests in various phyletic lines, and enable easy usage in the field by upgrading the base detection system, including standardization and simplification of methods. We will continue to proceed with the study to achieve these objectives.
Adherence sample setting for exposure test
Water content meter setting to measure the amount of water in the rock
Usuki Stone Buddhas, a National Treasure, are a group of “magaibutsu” (Buddha statues directly carved into rock face) sculpted niches that were carved on ignimbrites between the late Heian period and the Kamakura period. They consist of the following four clusters: the Hoki First Cluster, the Hoki Second Cluster, the Sannosan Cluster, and the Furuzono Cluster.
Weathering has partially progressed in these Buddha statues. Although protected by the niches from rainfall and winds, their surfaces have been impacted by repeated frosting and melting of underwater and rainwater during winters, and by flaking and granulating as a result of salt deposition due to evaporation in dry season. Therefore, weathering prevention methods such as building protective shelters, controlling river-bed water running behind the statues, and remounting falling pieces were adopted in the past. Tokyo National Research Institute for Cultural Properties (TOBUNKEN) has been engaged in these efforts for a long time.
A new joint research with Usuki City has now started to preserve and restore the Stone Buddha Statues. The surfaces around one knee of the seated Amitabha Tathagata Buddha statue in the Hoki Second Cluster have rebegun flaking and falling despite early preservation and restoration efforts. Via environmental research, we plan to monitor the change in temperature and humidity in the newly built protective shelters and review the water content in the rock, in addition to studying materials and implementing methods to strengthen and remount falling pieces. In preparation, we set the measuring equipment and adhesive samples for outdoor exposure testing on October 18th and 19th.
We plan to regularly review the measured data and observe the efficacy of adhesive samples against the weather, while continuing to discuss appropriate actions for the preservation and restoration of the Usuki Stone Buddha Statues with the Agency of Cultural Affairs, Oita Prefecture, and Usuki City.
Lecture on how to handle lab instruments
The Center for Conservation Science conducts scientific research on the conservation and restoration of cultural property. In 2021, we introduced a workshop on basic science, based on our research, for conservators who have diverse experience in restoration of cultural properties and museum curation and archiving.
The workshop was held for three days from September 29th through October 1st, 2021. We provided lectures and practical sessions on basic scientific knowledge that is important for conservation and restoration. It included basic chemistry, science of adhesion and adhesives, chemistry of paper, and pest damage control. The researchers of Tokyo National Research Institute for Cultural Properties delivered the lectures, based on their areas of expertise.
We received 44 applications from across Japan for 15 seats. Fifteen applicants, who either resided in or commuted to Tokyo, and had the desirable expertise, participated in the workshop keeping in mind the on-going COVID-19 pandemic.
The participants expressed their appreciation for this workshop through the questionnaires that were provided. We received requests for further scientific information on more advanced conservation and restoration cases. We intend to continue this workshop series to meet these expectations.
Investigation using X-ray fluorescent analyses
The Protection of Tumuli and Wall Paintings Project Team consisting mainly of researchers from Tokyo National Research Institute for Cultural Properties（TOBUNKEN）and the Nara National Research Institute for Cultural Properties has been working on research studies to preserve and restore the wall paintings of Takamatsuzuka Tumulus and Kitora Tumulus. Compared with the wall paintings of Takamatsuzuka Tumulus, the wall paintings of Kitora Tumulus are characterized by the twelve signs of the zodiac, depicted as animal heads on human bodies, three of which are featured on each wall along with the Four Divine Creatures and Star Atlas and others.
While six figures out of twelve—the Rat, Ox, Tiger, Horse, Dog, and Boar—have been identified, the Rabbit, Sheep, and Rooster are completely lost since the plaster where the paintings should be is missing. The rest, that is, the Dragon, Snake, and Monkey, are not yet identified because the surface of the walls is covered with mud. These three pieces of walls that could contain those paintings are currently not reassembled, but are preserved in the facility for conservation and restoration of Takamatsuzuka Tumulus wall paintings.
The material investigation group and restoration group of this project team worked together on an investigation using X-ray radiography in 2018 and found some radiographic images that seemed to show something drawn in the space where the Dragon was expected to be, but many questions remained. Then, in December 2020, X-ray fluorescent analyses were performed on the parts of the walls where the wall paintings of the Dragon and Monkey could possibly exist. Some mercury was detected, indicating that the figures might be present.
Following this outcome, on August 11th, 2021, further X-ray fluorescent analyses were conducted on the part of the wall where the Snake artwork was suspected to be. Three members of the Center for Conservation Science, TOBUNKEN—INUZUKA Masahide, HAYAKAWA Noriko, and CHI Chih lien—participated in this investigation. X-ray fluorescent analyses were conducted at spots distanced 2 cm apart where the Snake painting was expected to be. The detection of mercury indicated that the painting was indeed present.
These results were reported in the “29th Committee on Preservation and Utilization of Tumulus Wall Paintings” held on August 31st, 2021 by the Agency for Cultural Affairs.
X-ray image of the piece of the wall where the Snake painting could be present (left) and distribution of mercury signal strength (right)
Lecture on the Types and Characteristics of Restoration Materials
A Visit in Pest Control Practical Training
During a five-day period of July 5–9, 2021, we held the 2021 Training for Museum Curators in Charge of Conservation (advanced course). Last year, we held this training jointly with the National Center for the Promotion of Cultural Properties. In order to clarify the content of the training and to make it more beneficial for museum curators in charge of conservation, this fiscal year, we decided to divide the training into the “Basic Course,” implemented by the National Center for the Promotion of Cultural Properties, and the “Advanced Course,” implemented by the Tokyo National Research Institute for Cultural Properties.
The Tokyo Metropolitan Government has been implementing intensive measures to prevent the spread of COVID-19, and we thoroughly conducted temperature inspections, sanitization, and mask-wearing policies during the training.
Each laboratory of the Center for Conservation Science led the training on a one- or half-day basis, providing lectures and practical training in accordance with their respective specialties. Since advance-level courses are offered to people who have already received training for curators in charge of the conservation of museums, most of the attendees had an awareness of the issues and challenges faced by their own museums. On the last day, a lecture on disaster prevention and the mitigation of damage to cultural properties was given in light of recent natural disasters. This was a valuable opportunity to consider how to deal with and implement measures against natural disasters in museums, as well as the roles of the institutions in disaster prevention with regard to cultural properties.
In questionnaires, many participants stated that the training was helpful, such as by increasing the knowledge and skills that would be helpful in carrying out their work in the future.
This was the first time the training was held as an advanced course, but since the issues of the training have been clarified, we would like to improve it next year and in the future.
Survey of Armor by X-ray Fluorescence Analysis
At the request of the Kariya city Museum of History, INUZUKA Masahide of the Center for Conservation Science, conducted an analytical survey of a suit of armor. As part of these materials, the helmet became a designated cultural property of Kariya City in 1984. The location of items other than the helmet, such as the torso of the armor, only came to light a few years ago. The degree of damage to these other parts of the suit armor is much more severe than to the helmet, but they were additionally designated as cultural heritage by Kariya city in 2019 and deposited at the Museum.
A project to preserve and restore these materials will be implemented in the future. To collect basic data for this purpose, a structural survey using X-ray radiography and a pigment analysis using X-ray fluorescence analysis were conducted at Tokyo National Research Institute for Cultural Properties on May 31, 2021.
Images taken with X-ray radiography provided information on the structure of the helmet and torso, the number of components that comprise the armor, the position and number of studs, and other information. We also conducted an X-ray fluorescence analysis of the pale orange-colored portion on the surface of the helmet, leveraging a device that specializes in analyzing cultural properties, which are large in size and have a three-dimensional structure, with high sensitivity, as shown in the photograph. The results of these surveys will be used as reference materials for future restoration work.
A scene of the seminar
As part of a research project titled “Exhibition Environments for Conservation and Utilization” by the Center for Conservation Science, a seminar on “Exhibition Environments for Conservation and Utilization” – Relationships between Lighting, Colors, and How One Looks was organized to sum up research on lighting on March 4th, 2021. Reports on cases that put emphasis on ideal lighting for exhibitions at art and other museums while taking into account conservation of cultural properties had been predominant up until then. This time around, however, we asked experts in the area of lighting, which had not been taken up very much in the area of cultural properties, to share their insights into lighting with us from a perspective that was a little different from conservation.
First of all, Ms. SANO Chie, an honorary researcher at Tokyo National Research Institute for Cultural Properties (TBUNKEN), who had taken the initiative in this project, gave a lecture on the flow of research into lighting at the Center for Conservation Science as an introduction. This was followed by lectures that covered a broad range of subjects delivered respectively by Prof. MIZOKAMI Yoko (Graduate School of Engineering, Chiba University), who specializes in vision science, vision engineering, visual information processing, and color dynamics, Prof. YOSHIZAWA Nozomu (Department of Architecture, Faculty of Science and Technology, Tokyo University of Science), who studies evaluation techniques for architectural light environments, and Prof. YAMAUCHI Yasuki (Graduate School of Science and Engineering, Yamagata University), who carries out research on visual information processing, color dynamics, illuminating engineering, and image processing.
As a state of emergency was issued due to the COVID-19 pandemic, the seating capacity was limited to up to 30 in the seminar room, whose seating capacity is normally 120, but a face-to-face seminar proved extremely productive. Participants commented that the lectures delivered on a face-to-face basis were meaningful and that they were able to deepen their understanding of lighting, indicating that the seminar had a high satisfaction level. Meanwhile, we announced this seminar by limiting the recipients to art and other museums etc. in and around the Kanto region to prevent the spread of COVID-19. Thus, we decided to record the seminar and publish it on TOBUNKEN’s YouTube channel for a limited period of time. Let us encourage those who were unable to participate in the seminar in person to view it on this occasion.
You can view it from May 10th through July 30th, 2021 at:
https://www.youtube.com/watch?v=UQp68KyNvVQ
On February 16th, 2021, Tokyo National Research Institute for Cultural Properties and the Nara National Research Institute for Cultural Properties held a meeting of the Tumulus Mural Preservation Project Team. The Tumulus Mural Preservation Project is aimed at the permanent preservation of Takamatsuzuka Tumulus Mural and Kitora Tumulus Mural, both of which are national treasures. The two Institutes have been taking the lead in promoting the project for many years. Currently four teams, namely the conservation and utilization team, the restoration team, the material research team, and the biological environment team are conducting research, respectively. Tokyo National Research Institute for Cultural Properties, the Nara National Research Institute for Cultural Properties, and the Agency for Cultural Affairs held the 2nd meeting online as the state of emergency had been declared to prevent the spread of the novel coronavirus.
At the meeting, one team explained the creation of a 3D reconstruction model of the excavation and research areas of the tumuli. Other teams reported on the condition of the murals and non-contact optical analysis of the murals. The last team discussed the results of monitoring for microorganisms and the temperature and humidity at the preservation and management facility for Kitora Tumulus Mural as well as at the temporary repair facility for Takamatsuzuka Tumulus Mural. Careful discussion took place based on these reports. The reports consolidated at the meeting were made public at the 28th meeting of the Review Committee on the Preservation and Utilization of Tumulus Mural on March 23rd, 2021. Committee members gave suggestions and advice regarding the direction of future research and activities.
The handouts and minutes of the meeting are posted on the Agency for Cultural Affairs website. If you are interested, please see the link below.
https://www.bunka.go.jp/seisaku/bunkashingikai/kondankaito/takamatsu_kitora/hekigahozon_kentokai/index.html)
The repair of Takamatsuzuka Tumulus Mural was completed by the end of FY2019. The installation of a new facility that is suitable for public viewing has been under discussion. There are many issues to consider such as the load on the mural and changes in the environment associated with the transfer from the temporary repair facility to a new exhibition facility. Nevertheless, the project team will verify feasibility, taking into account the research on the permanent preservation of both murals conducted so far.
The seminar is underway
In the research project “Research on the Analysis of Materials, Structures and Conditions of Cultural Properties”, the Center for Conservation Science focuses on the physical and chemical characteristics of cultural properties based on the investigations of their materials and structures using various analytical methods. In particular, the Analytical Science Section has been studying the problem of the corrosion of lead composing cultural properties.
In order to summarize the research, a seminar on the “Corrosion of lead composing cultural properties and air environment” was held on December 14th, 2020. Invited were experts in art history (HASEGAWA Shoko of Seikado Bunko Art Museum and ITO Tetsuo of Agency for Cultural Affairs), conservation science (KOTAJIMA Tomoko of National Ainu Museum), and restoration (MUROSE Tasuku of Mejiro Institute of Urushi Conservation) were invited. At the seminar, lectures were presented on examples of art works consisting of lead, the current situation and problems concerning lead corrosion in art works, and basic knowledge of lead corrosion from a scientific point of view. In addition, the latest information about the relationship between lead corrosion and air environment and examples of restoration were shared and discussed. (Attendance: 20 individuals).
Inking ceremony at Shingu City Hall (Photo 1)
Replicated cenotaph (Photo 2)
The inking ceremony for the replica of the landslide disaster cenotaph in Kuju was held at Shingu City Hall on December 5th, 2020. The Kuju district of Shingu City is one of the affected areas of the rainstorm that the Kii Peninsula experienced in 2011. The district houses the stone monument built in remembrance of the tragedy of similar disasters seen in this area in the Edo Period. The Kuju Landslide Disaster cenotaph built in 1821 would get covered with overgrown shrubs, and its muddied surface made it difficult to read the inscription on it. Tokyo National Research Institute for Cultural Properties, therefore, precisely measured this cenotaph, and created a replica using 3D printing technology so that the unreadable characters of the inscription would be readable. As part of the citizen-awareness project for disaster preparedness, an event for this 3D printed replica was held at Shingu City Hall. The head of the Kuju district, the superintendent of education in Shingu City, the researchers involved in printing the replica, and the citizens took turns inking the engraved colorless characters of the replicated cenotaph (Photo 1) until they were readable even to the untrained eye, and suitable for being open to the public (Photo 2). Through this event, we could help people in the community recall the landslides that had occurred in the Edo Period, and contribute to increasing community disaster awareness.
Onsite investigation on Kozo (Daigo, Ibaraki)
Straw-made peeling board (Tool to peel Kozo)
Small knife to peel Kozo
Traditional materials and tools are indispensable for the restoration of fine arts and crafts. It has been harder to get such tools and materials in recent years. They are natural materials or are made from them, so it is becoming difficult to secure adequate resources due to changes occurring in the climate and environment. Additionally, a number of artisans who produce such tools and materials find it difficult to find a successor due to social changes such as an aging population even if the resources are secured. There are many such problems. Examples include Noriutsugi (Hydrangea paniculata) / Tororoaoi (Abelmoschus manihot) used for Neri (dispersants/thickeners) and silken threads to weave Sukisu (bamboo screen)—both of which are necessary for traditional Japanese papermaking—Tonoko and Jinoko (clay or soil powder) used for wood crafts, and silken threads produced using a traditional technique. It is difficult to secure the resources for these natural materials.
Concerned about this situation, the Agency for Cultural Affairs launched the “Support for the Management of Tools and Materials Used for the Preservation and Restoration of Fine Arts and Crafts” in FY2020. It is a financial support project for those who produce the tools and materials necessary for the preservation and restoration of fine arts and crafts. In order to receive a subsidy from the project, it is required to justify the necessity of the tools and materials based on scientific evidence and submit such data as videos of the production process and records of the tools/materials used for the restoration of cultural properties. Under these circumstances, Tokyo National Research Institute for Cultural Properties has investigated the tools and materials from the perspective of them not being produced in the future and provided support to those who produce such tools and materials in response to the request of the Agency for Cultural Affairs since FY2018. In FY2020, we conducted onsite investigations on Tororoaoi (Abelmoschus manihot) and Kozo (Broussonetia kazinoki x B. papyrifera) in Ibaraki; silken threads produced using a traditional technique in Nagano in September; Kozo (Broussonetia kazinoki x B. papyrifera) and tools to make Washi (traditional Japanese paper) in Kochi in October; and Tonoko (clay or soil powder) in Kyoto in November. In the case of scientific evidence is required during the course of an investigation, we conduct timely analysis to ascertain the validity and importance of the traditional tools and materials so that we can contribute to the implementation of measures to preserve future cultural properties.
Lecture on measures against biodeterioration
Lecture on scientific research on cultural properties
The abovementioned training was held from October 5th to October 15th, 2020. Although we have received many applications, the training was provided to 17 curators and others (or half the usual number) as a measure against the spread of COVID-19. Starting from last year, the training is implemented jointly with the National Center for the Promotion of Cultural Properties (CPCP). The CPCP took charge of the training sessions in the first week and Tokyo National Research Institute for Cultural Properties (TNRICP) in the second week. During the training, various control measures were thoroughly implemented to prevent the spread of infection: body temperature checking, sanitizing, and avoidance of the “3C’s.” Moreover, the participants wore gloves during hands-on training sessions. Furthermore, training materials were distributed to each trainee.
During the first week when the CPCP was in charge, participants learned the basics of the conservation environment through classroom lectures. In addition, reports were made on the instruction and advice regarding the “Virus Removal and Disinfection Work at Museums, etc.” addressed jointly by three organizations, namely the Agency for Cultural Affairs, CPCP, and TNRICP. During the second week, certain sections at the Center for Conservation Science provided separate half-day sessions and provided classroom lectures and practical workshops with a variety of topics such as the concept of conservation and restoration of cultural properties, the method of addressing on-site issues with the application of basic natural science knowledge, and other topics. Participants appreciated these sessions, commenting that they were informative and useful. On the last day of the training, Dr. KOUZUMA, Director of the Cultural Heritage Disaster Risk Management Center established in October 2020, was invited to give a lecture on the “Disaster Risk Management of Museums,” which turned out to be a valuable occasion to think about the role played by museums in protecting cultural properties from disasters.
We will keep working to provide better trainings to suit the needs of the time in 2021.
X-ray radiography of Kongo Rikishi statue
The Oiwayama Bishamonten in Ashikaga city, Tochigi prefecture is said to be one of the three major bishamontens in Japan in addition to those at Kurama-yama in Kyoto and at Shigi-san in Nara. Wooden Kongo Rikishi statues, which are cultural properties designated by Ashikaga city, are enshrined at Sanmon gate. According to recent research, there are concerns about the deterioration of these properties over time. In particular, the inclination of the head of Agyo statue has been pointed out. Considering this situation, the owner plans to embark on a restoration project.
To carry out the project, it is necessary to clarify the inner structure of the statues, especially how the parts are connected to each other. However, an in-situ and non-invasive investigation is required without transferring statues, which are about 2.8 meters tall, from Sanmon gate. At the request of the owner via Ashikaga city, Masahide INUZUKA conducted an investigation into the inner structure of the statues using X-ray radiography from September 9th to 10th, 2020.
As shown in the photograph, the X-ray was irradiated on Kongo Rikishi statues from an X-ray tube set on the scaffold assembled in front of the statues. Before conducting the investigation, important discussions were done to determine how imaging plates (IPs) should be set in the limited space behind the statues. For this research, we used the developing equipment, which is dedicated to IPs, and proceeded with the research by confirming the X-ray transmission images each time they were obtained.
From the X-ray transmission images obtained during the above research, the inner structure of the statues and the information about positions and numbers of nails used in past restoration works were revealed. Such information will be referred to during the restoration works in the future.
Field survey
DNA base sequence analysis
The Biological Science Section of the Center for Conservation Science has been promoting basic research on a new technology useful for detecting cultural property pests or pest identification methods that use DNA analysis. In order to specify the type of a cultural property pest, we generally identify the species by comparing the characteristics of the external morphology of the pest with information described in pictorial books and specialized guides. The similar external morphology of some pests will make type specification difficult and require specialized knowledge, including dissection and comparison of body details. In addition, we frequently experience a situation that allows us to obtain only limited parts of their bodies. Therefore, we have been analyzing some specific regions of DNA of cultural property pests, creating a unique database of base sequence information specialized for cultural property pests, and attempting to apply the “DNA barcoding” method to conduct type specification by using DNA obtained from unidentified samples.
We conducted a field survey from August 6th to 7th, 2020, in the historical wooden structures in Nikko, Tochigi Prefecture, in an attempt to capture several species of Anobiidae not registered in the database. With no effective traps available to capture target Anobiidae during the field survey, we conducted persistent research, checking every detail of the damaged wooden structures, which resulted in the capture of several species of Anobiidae.
To date, we have determined the DNA base sequences of about 40 major cultural property pests, including the individuals obtained from this field survey, and are now proceeding with the creation of the database. Included in it are many types unregistered in the public database. We can safely say that it is a matter of great importance to build a database specializing in cultural property pests.
Hereafter, we plan to develop technology to identify the pests from their body parts such as legs and wings, extract DNA from molting shells and manure left in damaged parts, and identify the “criminal” that has harmed cultural properties.
Measuring of fine particles in the visitor corridor
The 29th Public Exhibition of the Conservation Facility for Mural Paintings of Takamatsuzuka Tumulus, a National Treasure, was canceled because the number of the cases with novel coronavirus was so increasing. With sufficient infection prevention supervised by public health specialists, the 30th Public Exhibition was held from July 18th to July 24th, 2020. Tokyo National Research Institute for Cultural properties sent four researchers as expositors for the visitors.
In this public exhibition, the azure dragon painted on the east wall, the black tortoise on the northern wall, female figures on the east and west walls, which were restored last year, were placed near the visitor corridor.
Before viewing these wall paintings, we asked visitors to measure their body temperature, report their health condition in the last two weeks, and disinfect their hands frequently. The number of daily visitors were restricted to 100 in the viewpoint of avoiding crowded in the corridor for visitors. While face to face instructions have been done previously, we installed audio guides and answered the questions from visitors outside to protect them against droplet infection. We also ventilated the corridor with a blower, and cleaned the surface inside with alcohol.. As specialists of conservation science, we offered technical supports to insure visitors’ safety, such as monitoring the concentration of carbon dioxide as the index of ventilation and measuring the number of droplet particles with a particle counter to check the air quality.
The application for public exhibition in this coming winter is available form the link below:
http://www.bunka.go.jp/seisaku/bunkazai/takamatsu_kitora/sagyoshitsu_kokai/index.html
