|■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
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:
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.
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.
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:
In 2020, the novel coronavirus (COVID-19) infection spread all over the world. On April 7, the Japanese government issued a state of emergency to seven prefectures, and on April 16, they expanded the target areas to all prefectures. Facilities possessing cultural properties also found it necessary to prevent the spread of the COVID-19 infection and then they encountered the concerns about the impact disinfection might cause to cultural properties. The Agency for Cultural Affairs issued an administrative contact on April 23, “Regarding the measures for virus removal and disinfection work to be taken by cultural property owners and administrators of facilities for the conservation and public display of cultural properties.”
The Agency warned the departments responsible for cultural properties across the country that disinfecting chemicals could cause deterioration of cultural properties, therefore some cases would require cautions in using those chemicals; and when any department faced the necessity of engaging in disinfection work for cultural properties and needed professional advice, it should consult the Agency beforehand. They asked the following three organizations — the Agency for Cultural Affairs, the National Center for the Promotion of Cultural Properties, and the Center for Conservation Science of Tokyo Cultural Properties Research Institute — to cooperate and provide the service as the consultation desk to respond to the situation. Our Institute has posted on its website that it is available to accept technical consultations regarding disinfection. (http://www.tobunken.go.jp/info/info200424/index.html).
So far, we have received a wide range of consultations including not only on disinfection in museums, art museums, exhibition rooms and storage of archives, but also on the disinfection of buildings as well as folk cultural properties used for festivals. In response to these consultations, our Institute has advised to minimize the usage of chemicals for disinfection and instead employ other infection prevention countermeasures. Even in cases absolutely requiring disinfection, we have advised on how to respond or on how to ventilate in the best possible manner according to each situation. Hereafter, while constantly examining the need for disinfection, we are going to keep responding to the situations as a consultation desk.
Guidance using a video projection screen before the tour of the mural painting conservation facility
During the seven days between January 18th and January 24th, 2020, the mural paintings conservation room of the Takamatsuzuka Tumulus was opened to the public.
Beginning in 2008, this was the 28th time the mural paintings were opened to the public. During this period, four researchers from Tokyo National Research Institute for Cultural Properties (TNRICP) worked as staff.
In this exhibition, the black tortoise drawn on the north wall, the northern divine creature that symbolizes “winter,” the female figures painted on the west and east wall, and the male figures drawn on the west and east wall were placed to the side of the walkway for visitors. Many visitors have confirmed the current state of all mural paintings.
In recent years, the difference in the condition of the murals post cleaning became increasingly evident and many visitors were amazed by the difference between the mural paintings and the photos of them displayed on the wall in the conservation room. Additionally, there were those who compared the drawn black tortoise to that in the Kitora tumulus mural paintings exhibition, which was held at the same time at the Center for Preservation of Kitora Tumulus Mural Paintings.
A series of projects related to mural paintings of the Takamatsuzuka Tumulus are being conducted by the Agency for Cultural Affairs under the overarching project entitled “Research in relation to permanent preservation measures of the National Treasure Takamatsuzuka Tumulus.” In addition, the TNRICP has been centrally involved in the work for many years. The murals paintings have been taken out of the mound alongside the stone material from the mounds in 2007. After that, the conservation treatment of the painting or plain surfaces contaminated with mold and biofilm occurs and plaster with advanced porosity is consolidated and stabilized at the temporary conservation facility near the tombs. In this 12th year since the start of the conservation project, it will reach a break once. Research of conservation and utilization of the mural paintings will have continued by the time it exhibits in a new museum.
As cultural properties attract more attention, conservation and restoration measures have been required for works comprised of various materials in recent years. Under the circumstances, conventional measures are inapplicable in many cases. It is of particular importance that we clean the works without diminishing their value.
To meet these growing needs, the Center for Conservation Science invited Dr. Paolo CREMONESI, conservation scientist from Italy, to organize a workshop on basic scientific knowledge of cleaning and usage of gels from October 8th through 10th, 2019. On October 11th, a seminar on restoration measures for cultural properties was also held to raise on-site issues and introduce the latest research on cleaning of Japanese and Western cultural properties.
With regard to the workshop, lectures were delivered in the seminar room in the morning (to 56 participants). During the afternoon training in the conference room, 21 trainees learned how to prepare cleaning solutions used for the restoration of cultural properties and how to actually clean them.
At the seminar, Dr. Cremonesi delivered a lecture on “Cleaning Methods in Western Countries –Application of Gels and the Latest Cases,” in addition to “Cleaning of Oriental Paintings” by Ms. YAMAMOTO Noriko, Representative Director of the Association for Conservation of National Treasures, and “Potentiality of Gels Applicable to Paper and Photo Works” by Ms. SHIRAIWA Yoko, photo restorer. They introduced the current state of restoration sites in the East and the West. TORIUMI Hidemi and HAYAKAWA Noriko from the Center for Conservation Science gave lectures on the “Historical Background of Cleaning Methods Developed for Western Paintings” and the “Development of Cleaning Solutions for Cultural Properties – Introduction of Recent Studies,” respectively.
The abovementioned training was held from July 8th to 19th, 2019. After receiving more than double the amount of applications than the number of places available this year, we managed to provide training for 31 curators and museum officials.
This year’s training was the first one which was 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, with the lecture programs being completely altered. During the first week, participants learned about the basics of the conservation environment through classroom lectures and practical workshops, while the CPCP shared useful information on social media. With the training this year being jointly held, it became clear that we lacked the ability to deliver the information adequately.
During the second week, certain sections at the Center for Conservation Science provided separate half-day sessions respectively, and provided classroom lectures and other programs under the following topics: scientific study on cultural properties (Analytical Science Section); measures to prevent biodeterioration damage (Biological Science Section); conservation of outdoor cultural properties (Restoration Planning Section); thermal environment control (Preventive Conservation Section); and types and attributes of restoration materials/conservation and restoration of paper artworks/cultural properties of Japanese painting (Restoration Materials Science Section). These programs dealt with a wide range of issues, including methods to apply concepts and basic knowledge of restoration in relation to actual issues and a workshop to learn how to use TNRICP’s latest technologies and achievements for on-site work. Participants appreciated these sessions, commenting that they were very helpful.
In 2020, we believe that it will be quite difficult to hold the training in July due to the Tokyo Olympics and Paralympics and other relevant events. In order to prevent any inconvenience for participants, we will let you know about the schedule for the next planned training immediately after it is decided.
Preparing to measure ventilation volume
From 2017, Rikuzentakata City have entrusted Tokyo National Research Institute for Cultural Properties with inspecting and improving the storage environment of cultural assets at the City Museum that were damaged by a natural disaster. Based on our inspections, we were consulted on issues and countermeasures relating to atmospheric pollution and indoor air pollution affecting cultural assets and the human body, proposals to improve on the management of cultural assets, and proper methods to care for damaged materials.
The first on-site inspection of 2019 fiscal year was performed on June 27th and 28th, 2019. The Rikuzentakata City Museum stored the damaged cultural assets in an elementary school building by making requisite modifications. This year, efforts are focused on the ventilation of a classroom used as a storage room. We hope to be of assistance in this project while cooperating with the several groups involved in the restoration of the damaged materials.
A scene from the workshop
The 2nd workshop for specialists on the new insecticidal treatment for historical wooden buildings, known as “humidity-controlled warm-air treatment,” was held on May 9th, 2019.
Pest-borne damage to historical wooden buildings risks not only the loss of important wooden materials but also building safety, as the wooden materials can become hollow, thus weakening the strength of the lumber construction material and the building itself. In response to severe pest-borne damage, the Rinno-Ji Temple at Nikko has undergone closure and repair. Fumigation with sulfuryl fluoride gas, which is known to have almost no effect on cultural properties, was performed to eradicate all noxious pests in the building. However, there are huge health and safety risks associated with the use of mass fumigation with poisonous chemical substances, and such treatment can also dissuade neighboring institutions from opening to the public.
To address this issue, humidity-controlled warm-air treatment was developed as a new insecticidal treatment. This method eliminates pests by increasing the temperature to 60 degrees Celsius while regulating the humidity without altering the water content of the wood, thus minimizing any damage to the wooden content. Two successful domestic cases have been reported with no significant damage found in buildings containing Urushi (Japanese lacquer) decorations. Subsequent examination of these cases indicates that the technology used in this new treatment is nearly ideal. Nevertheless, concerns have been raised regarding the number of technicians required and the cost involved, which must be addressed before formally establishing humidity-controlled warm-air treatment as a valid insecticidal treatment. Also, since this a newly developed treatment, its long-term performance is difficult to evaluate; there may be as yet unknown effects inherent in the use of this treatment.
Several issues must be resolved before humidity-controlled warm-air treatment can be considered to be an established insecticidal treatment method. We look forward to working over the long-term in cooperation with related organizations.
Many museums frequently ask for our advice on how to reduce the concentration of ammonia and acetic acid kept inside their repositories and exhibition cases. Ammonia accelerates discoloration of oil paintings, while acetic acid badly erodes metallic goods, especially artifacts and coins containing lead. This work is indispensable for preserving cultural assets.
This guide, edited by the Preventive Conservation Section, is the fruit of research on display environment for preservation and utilization. You can read it from April 2019 in the notice exhibited on the first page of Center for Conservation Science on the website of Tokyo National Research Institute for Cultural Properties (in Japanese). We have intended to provide content covering the basic knowledge of air cleaning, monitoring pollutions, and their countermeasures so that all kinds of people can use the guide, including curators, workers entrusted with controlling air conditioning, and researchers. The end of the guide presents “frequently asked questions” with an easy access to the pages referred to in the answers. The appendix explains concrete processes of measuring methods using many pictures. We have also provided reference books and documents for those who want to know more details.
It will be our pleasure if this can help improve the environment of museums.
Ongoing general discussion
In recent years, cultural properties have been attracting more attention. In response to their promoted utilization, the number of cultural properties that need restoration has been increasing. Under the circumstances, conventional restoration approaches and concepts are not applicable in many cases. In the light of the current situation, the “Seminar on the Current Status of Restoration of Cultural Properties and Its Issues” took place on November 22nd, 2018. Sharing a restoration overview of the past, experts specializing in cultural property areas introduced the issues identified during the current restoration process.
Guest Professor Toshikazu SASAKI from Hokkaido University, who specializes in historical materials, delivered a lecture on the conservation of historical materials and issues of conservation of folk materials under the title of “Thoughts on Restoration of Arts and Crafts” based on his vast experience accumulated in the Tokyo National Museum, the Agency for Cultural Affairs, and the National Museum of Ethnology. Senior Specialist Tomohiko JINUSHI from the Agency for Cultural Affairs reported “Achievements and Issues in Recent Restoration of Historical Materials” including detailed cases under the existing conditions. Curator Hitomi KITAMURA from the National Museum of Modern Art, Tokyo presented the details of recent restoration of the collection and the issues in that process under the title of the “Current Status of Restoration of Cultural Properties and Recent Issues -With a Focus on ‘Twelve Hawks’-.” Chief Noriyuki NAKANO from the Kyoto Prefectural Government reported what kinds of discussions are actually conducted in restoration and how necessary decision-making should be done. During the general discussion, the audience asked many questions, which resulted in an active Q&A session. The seminar attracted 104 people, who expressed expectations for our continually providing an opportunity to exchange information on the restoration of cultural properties on a large scale through a post-seminar questionnaire survey. The details of this seminar will be published as a report next year.
The Center for Conservation Science has been developing materials required for the restoration of cultural property. One of the items subject to our research is glue. Glue, an animal collagen hydrolysate, has been used as an adhesive since ancient times. According to the information found, the kinds of animals used for producing glue vary and different measures have been used to find better ways to manufacture it. On the other hand, it has not been scientifically defined whether the raw materials and manufacturing methods have any effect on the properties of glue. In recent years, research on the raw materials of glue and its manufacturing methods has finally been carried out. Based on these results, the Restoration Materials Section has been conducting research studies on the characteristics of glue as a restoration material.
On the case of the restoration of a famous Japanese-style painting, “Jo-no-mai (Noh Dance Prelude,” designated as an Important Cultural Property, the suitable glue was selected based on the outcomes of the studies. It is notable that by using glue which keeps whiteness of shell chalk, restoration, which minimizes the possibility of changes in original works, was implemented.
These outcomes were displayed in the Chinretsukan Gallery of The University Art Museum, Tokyo University of the Arts for the Exhibition “Animal Glue and Conservation – To Keep ≪Jo-no-mai≫ -.” The exhibition was co-organized with the Conservation Science Laboratory, Graduate School of Conservation, Tokyo University of the Arts from October 14th to 19th, 2018. In cooperation with Nikawa Labs as one of the organizers, the exhibition displayed the actual glue used for restoration, scientific data, and numerous images including enlarged ones taken during the restoration process. In addition, a visiting researcher, Kentaro UDAKA, delivered gallery talks. This exhibition provided a valuable opportunity for visitors to gain a broad understanding of the relations between research outcomes and the workplace for the restoration of cultural properties.
“Humidity-controlled high-temperature treatment for the bell tower of Chuzen-ji Temple in Nikko (branch temple of Rinno-ji Temple) and on-site inspection”
On September 10th, 2018, we visited Chuzen-ji Temple to inspect the “Humidity-controlled warm air treatment ” for its bell tower. This treatment method aims to expel noxious insects harming pillars and beams of wooden structures under a high temperature (around 60°C). Usually, as the temperature increases, wooden building materials crack or strain. However, it is possible to increase the temperature inside the wood almost without affecting its physical property, since the temperature rises while the humidity in the treated space is controlled with the wood water content maintained at a certain level. The conventional yet sole insecticidal method for historical wooden structures is fumigation treatment, where a structure sealed with covering is filled with vaporized pesticide to exterminate noxious insects inside the wood. However, vaporized gas also affects human health, thus, requiring safety measures against greater risks. Accordingly, it was hard to implement such large-scale treatment for wooden structures continually. This Humidity-controlled warm air treatment is expected as a new approach to overcome such a challenge.
So far, a research team comprising the Association for the Preservation of the Nikko World Heritage Site Shrines and Temples, Kyoto University, Kyushu National Museum, Total System Laboratory Co., the Japanese Association for Conservation of Architectural Monuments, National Museum of Ethnology, Natural History Museum and Institute, Chiba, and Tokyo National Research Institute for Cultural Properties has been proceeding with the studies from basic research for application to old wooden buildings to establishment of application technique. In the basic research, we verified the humidity distribution in the treated space during the test with a chamber, as well as the temperature distribution inside the wood, measured surface strain, and effects on wooden materials. Then, following the treatment testing with a model structure by using a pilot unit manufactured to control the temperature and humidity of actual structures, we finally realized on-site treatment testing of a historical wooden structure for the second time in Japan after Aizendo Hall of Chuzen-ji Temple. We would like to move ahead with this research toward the dissemination as one of new insecticidal methods while organizing these two treatment test results obtained from two buildings of Chuzen-ji Temple.
Discussion during IIC 2018 Turin Congress
The congress of the International Institute for Conservation of Historic and Artistic Works (IIC) was held from September 10th to 14th in Turin, Italy. From Tokyo National Research Institute for Cultural Properties, Dr. Masahide INUZUKA of the Center for Conservation Science participated in the congress.
The theme of this congress was “preventive conservation.” Therefore, as well as the specific topics about conservation environments, material analyses and restoration, the importance of preventive conservation, leadership required for experts, public engagement and other relevant subjects were discussed.
In the session about preventive conservation for historic sites, Dr. Inuzuka made a presentation on the condensation problems and their preventive measures in a conservation facility for a decorated tumulus in Japan. In the poster sessions, the history of the environmental inspection of museums conducted by the Preventive Conservation Section was reported and information was exchanged with attendants from other countries.