The 15th International Conference of the Infrared and Raman Users Group (IRUG)

IRUG group photo

A practical research workshop

　The 15th International Conference of the Infrared and Raman Users Group (IRUG) was held for the first time in Asia, at the Tokyo National Research Institute for Cultural Properties (“Tobunken”) from September 26 to 29, 2023, in collaboration with the Conservation Science Laboratory of Tokyo University of the Arts (“Geidai”).
　IRUG is establishing a forum for the exchange of infrared and Raman spectroscopic information and reference spectra for the study of the world’s cultural heritage. Both FT-IR and Raman spectroscopic analytical methods are very effective for determining material information when surveying cultural properties. In recent years, the investigation of cultural properties using these analytical methods has progressed, and many results have been reported.
　There were 51 oral and poster presentations at the international conference. The keynote talk, covering aspects of the theory and challenges of reflectance-mode infrared spectroscopy, was given by Dr. James A. de Haseth, Professor Emeritus of Chemistry at the University of Georgia (USA). A featured workshop covering reflectance infrared spectroscopic techniques, with focus on data acquisition, processing, and interpretation, was led by Dr. Marcello Picollo (Senior Researcher at IFAC-CNR) and aided by Dr. Suzan de Groot (RCE, The Netherlands), Prof. Manfred Schreiner (Akademie der Bildenden Künste, Austria), with sponsorship and other aid from Thermo Fisher Scientific Corporation, and Bruker Corporation.
　Throughout the conference, active discussions were held on methods of analysis and conservation of cultural property materials. The Center for Conservation Science will continue to observe international trends as it works to advance our research projects.

Investigation of Techniques and Raw Materials to Conserve Cultural Properties Related to Traditional Musical Instruments in the Republic of Korea

Tapping lacquer in South Korea

A Daegeum in which red lacquer was applied to the inside

　With the cooperation of the National Intangible Heritage Center in the Republic of Korea, the Department of Intangible Cultural Heritage and the Center for Conservation Science of the Tokyo National Research Institute for Cultural Properties (TOBUNKEN) jointly investigated the current situation regarding procurement of bamboo materials and urushi lacquer used to adjust the inner diameter of Japanese traditional wind instruments, and the succession of related techniques that developed in the Republic of Korea, where bamboo is used for their traditional wind instruments as in Japan.
　In this investigation, we learned that bamboo logging associated with the development of residential and commercial lands is popular in Korea. Therefore, the general bamboo materials are in plentiful supply. On the other hand, the supply of some special bamboo materials such as ssanggoljuk (double-groove bamboo) used for daegeum, a traditional Korean bamboo flute, is unstable. Therefore, the Research Institute for Musical Instruments of the National Gugak Center developed a new material made by flatting bamboo to thin plates and bonding them under pressure, obtained a patent, and made this technique public. However, this new material is not yet widespread among instrument manufacturers or daegeum players. We understand the challenges involved.
　Regarding urushi lacquer, we were impressed that the workers involved are well-protected to increase domestic production and demand for urushi lacquer liquids to change the current situation that many lacquer liquids are imported from China. We understand that the challenges related to the tools and materials used to restore the urushi lacquer products are not as severe in Korea as in Japan. For example, people we interviewed said that in Korea there are more than ten shops that process and sell mother-of-pearl shells, which are especially used for decoration.
　In Korea, it is not popular to apply lacquer to wind instruments at present. However, red lacquer was applied inside of daegeum in the past. Even now, red lacquer is sometimes applied for decoration. We wonder about the original reason why the red lacquer was applied in the past.
　In Japan, multiple lacquer layers of urushi lacquer are applied inside of the wind instruments to adjust their inner size. In Korea, the inner size is adjusted by shaving the inside of the bamboo, which has thicker and denser walls. These very different techniques provide an interesting contrast.
　We will continue our investigation to find solutions to the challenges by comparing the challenges in Japan to secure the raw materials and success of the conservation techniques implemented in other countries that use the common raw materials, and by understanding the characteristics of each technique.

Installation of a lid aimed at preventing the accumulation of dust on the wall paintings of the national treasure Kitora Tumulus

Lid delivery

Lid in place (east wall)

　The Kitora Tumulus Mural is a national treasure that depicts the four deities, the twelve signs of the Chinese zodiac with beast heads and human bodies, and astronomical images. It has been repaired after it was removed from the inside of the tomb, and is now stored with the mural face up at the Kitora Kofun Mural Conservation and Management Facility in the “Hall of Four Deities” located in Asuka Village, Takaichi County, Nara Prefecture. Until now, dust has been prevented from entering the storage room using a dust remover in the front room. However, the visible dust on the wall painting that was brought into the room and could not be removed has been an issue for many years. As there is risk of damaging the mural when removing dust, the installation of a lid to prevent the accumulation of dust on the mural was considered. The Agency for Cultural Affairs, Tokyo National Research Institute for Cultural Properties, Nara National Research Institute for Cultural Properties, and the Association for Conservation of National Treasures (ACNT) have discussed the elements required for the lid, which does not adversely affect the mural, is easy to handle, allows the mural to be seen with the lid in place, and made of a material that does not attract dust. At the Kuroda workshop (Representative: Mr. USUI Hiroaki), a manufacturer of traditional fittings, whose technique is designated by the government as one of the Selected Conservation Techniques, a wooden frame covered with a transparent antistatic sheet was made as a prototype lid. Because it was confirmed in FY2021 that there is no difference in temperature and humidity inside and outside the lid, the possibility of adverse effects on the mural is extremely low. Thus, the finished product, with improvements in terms of strength, was delivered on March 24, 2023, and the lid was installed on the Kitora Tumulus Mural. We plan to confirm the effectiveness of the installation of the lid and discuss with the relevant parties how to handle the lid during mural inspections, public openings, and inspections.

Video Documentation of the Manufacture of Carving Tools for Sculpture – Recording Survey of Tools and Raw Materials used for the Preservation and Restoration of Art and Craft Objects

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.

Basic Research for Preservation and Restoration of Usuki Stone Buddhas, a National Treasure

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.

The 2nd Meeting of Tumulus Mural Preservation Project Team in FY2020 Held Online

　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 30th Public Exhibition of the Conservation Facility for Mural Paintings of Takamatsuzuka Tumulus, a National Treasure

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

Opinion Exchange with Bagan Lacquerware Technology College and Visits to Lacquerware Production Sites in Myanmar

Visit to a lacquerware production site in Myanmar

　The Tokyo National Research Institute for Cultural Properties conserves and restores cultural properties, as well as conducts research and study in collaboration with educational/research institutes, private and other organizations, not only at home but also abroad. As one of these activities, the Institute reached an agreement on the protection of lacquer work cultural heritage in Myanmar with the Small-Scale Industries Department of the Ministry of Co-operatives, Myanmar in 2014 while organizing a workshop on lacquerware at Bagan Lacquerware Technology College in 2016. Even after the expiration of the agreement, another workshop was held at the College in February 2017, where lacquerware was practically observed and lectures on conservation/restoration cases and scientific analyses were given, maintaining the cooperative relationship.
　On December 7th, 2017, we visited the College to decide on the policies for future cooperative programs by exchanging opinions. Its main topics were the safety and features of lacquerware sold in the Bagan area from a scientific perspective, and both parties agreed that mutual understanding should be promoted further. In addition, we visited lacquerware production sites in Myanmar for future cooperation on December 7yh and 8th, promoting a better understanding of Myanmar’s lacquerware.

Research on the great Torii of Itsukushima Shrine after restoration

Research on the great Torii of Itsukushima Shrine

　The Center for Conservation Science has studied restoration materials for cultural properties.
　The great Torii of Itsukushima Shrine is located on the coast. Since it is exposed to the wind, the rain and the waves, we have to select restoration materials with high weathering performance, which can also save restoration time.
　Based on the above, we studied which fillers and surface-finishing agents were the most suitable for use in the great Torii from 2010 to 2016. After a small pillar of the great Torii was partially restored last year, we researched it on May 25.
　We are going to observe the progress and cooperate with conservators for restoration planning.