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.

Survey for the conservation and restoration of an early 20th century aircraft

Confirmation of paint stain removal status

Confirmation of surface using microscope

3D model obtained by SfM-MVS

　Unlike ancient cultural heritage items created using traditional materials and techniques, many modern cultural heritage items were created using relatively new technologies brought to Japan after the Meiji period (1868-1912). Furthermore, modern industrial products created for mass production and mass consumption are generally difficult to preserve over the long term. One of the research themes of our laboratory is how to preserve cultural heritage from such a relatively recent era for the future.
　In March 2023, we conducted a survey of aircraft components from the 1910s stored and displayed at the Matsuiya Sake Brewery Museum (松井屋酒造　Tomika-cho, Gifu Prefecture). The survey aimed to collect information about the appropriate preservation method and the direction of utilization of the materials, following an actual inspection of and discussion about the materials with the Tomika-cho Board of Education, the Matsuiya Sake Brewery Museum, and others in May 2022.
　The surveyed part is believed to be the horizontal tailfin of a French Salmson Model 2 double-seat reconnaissance aircraft (Salmson 2A2), manufactured by another company in France under license from Salmson(YOKOKAWA Yuichi, “On the Salmson 2A2 Fuselage Parts Remaining at the Matsuiya Brewery,” Aviation Fan, December 2021). In 1918, at the end of World War I, the Japanese Army purchased 30 of these planes, and it is estimated that the material kept at the Matsuiya Sake Brewery Museum comes from one of them.
The paint is visible on the entire front and back of the tailfin. It is highly likely that it is the original paint from the 1910s, and if so, it may be the only aircraft component in the world that still has the original paint from that period (YOKOKAWA, above).
　To examine the possibility of conservation and restoration and its methods, we checked stain removal status with partial dusting and the removal of dirt using water and other methods. With the cooperation of the repair technician, we confirmed that there was a high probability that the original paint was still extensively in place and discussed specific cleaning methods.
　Although the survey confirmed which cleaning method is to be used, many points still need to be considered in its implementation. We will continue to work with the Matsuiya Sake Brewery Museum, Tomika-cho Board of Education, and other concerned parties to find solutions for the preservation of the aircraft components.

Investigation of Modern Cultural Heritage in Minamikyushu City

Investigation of " Hayate"

The air quality Investigation

Filming of the former Chiran Airport water tower

Investigation of the former Aoto Airfield pillbox

　Tokyo National Research Institute for Cultural Properties (TOBUNKEN) worked with Minamikyushu City for “memorandum concerning the conservation and restoration of cultural properties designated by Minamiyusyu City”, and recently started joint research in July, 2022.
（https://www.tobunken.go.jp/materials/ekatudo/996061.html）
　The following surveys and investigation were conducted in Minamikyushu City in February, 2023.

Investigation and advice on preservation and restoration of the former Japanese Army Type 4 fighter “Hayate”
　The “Hayate” (designated cultural property of Minamikyushu City), which is stored and exhibited at the Chiran Peace Museum, was captured by the US military in the Philippines during the Asia-Pacific War and is the only surviving aircraft.
After a test flight by the US military, it was sold and passed through multiple owners before it was returned to Japan in 1973. When the town of Chiran (now Minamikyusyu City) was established in 1995, the aircraft was transported there and has been on display at the Chiran Peace Museum since 1997.
　Since 2017, Minamikyushu City has been conducting a conservation survey, and TOBUNKEN has participated in the survey from 2018. Our findings suggest that overall, the fuselage is in good condition, but some parts have worn out or been replaced because of the post-war test and demonstration flights. We will continue to check the status of the remaining original parts and consider the restoration policies. In this investigation, we mainly targeted the engine, checked the original parts, and the condition inside the engine and oil tank, among other things. Some parts removed from the aircraft were entrusted to TOBUNKEN for cleaning and component analyses.
　The research was conducted in the exhibition room. Since the exhibition room was not closed during the research period; visitors were able to observe it at that time. Additionally, a report on the state of preservation was published in March, 2022.

Air quality investigation of exhibition rooms and storage in the Chiran Peace Museum
　In this study, we conducted an air quality investigation (inspection of organic acids, aldehydes, and volatile organic compounds [VOC]) in the exhibition room and storage room along with a survey of ” Hayate.” In the future, we plan to consider a more stable exhibition and storage environment based on the results of this investigation.

Records of the current state of concrete structures during the Asia-Pacific War in Minamikyushu City
　Minamikyushu City has there are cultural assets related to numerous wars and the former Chiran Airfield. They have remained in the city since the Asia-Pacific War period. Many of them are concrete structures, but nearly 80 years have passed since the end of the war, and they are deteriorating and falling debris. In this study, we recorded the current situation by obtaining actual measurements and photogrammetry (three-dimensional models were created from multiple photographs) of the former Chiran Airfield water tower (a city-designated cultural property) and two pillboxes (defensive positions) of the former Aoto Airfield as concrete structures in the city during the relevant period. In the future, we will analyze the progress of deterioration based on regular records and consider measuring concrete strength.

Investigation of Coloring Pigments Used in Kangetsu-do Hall of the Kotoku-in Temple

Investigation at Kangetsu-do Hall of the Kotoku-in Temple

　The Kotoku-in Temple, famous for its Great Buddha, has a hall called Kangestu-do Hall, transferred from Gyeongbokgung, a Korean royal palace. Kangetsu-do Hall faces various issues for its conservation and utilization, such as aging roofing tiles and outer walls as well as damage by wild animals. Dancheong were the original coloring pigments used in Kangetsu-do Hall at the time of its construction. This is very valuable because they exist in their original state. Their elements have not yet been elucidated; therefore, it is important to understand their status. Through these examinations and discussions, we decided to collect basic information related to the coloring pigments used in Kangetsu-do Hall.

　Responding to the request by the Kotoku-in Temple (chief priest: Prof. SATO Takao), INUZUKA Masahide, HAYAKAWA Noriko, HAGA Ayae, and CHI Chih lien of the Center for Conservation Science of Tokyo National Research Institute for Cultural Properties (TOBUNKEN) conducted on-site investigation of coloring pigments on the building components of Kangetsu-do Hall using portable analytic equipment on July 6th and 7th, 2022.

　As this investigation’s first step, reflectance spectrometry was conducted using a hyperspectral camera to investigate two-dimensional color information, focusing on the places where the original paintings from the construction time were presumed to remain. We then selected some places that were academically interesting based on the reflectance spectrometry data and performed further detailed analysis using X-ray fluorescence analysis. We plan to analyze in detail the data obtained by these two types of analysis methodologies, further investigate the unique coloring pigments used in the Joseon Dynasty, and use this information for future conservation and utilization.

MoU for Research on Conservation and Restoration of Cultural Properties in Minamikyushu City Concluded

SAITO Takamasa, Director General of TOBUNKEN and Mr. NURUKI Hiroyuki, Mayor of Minamikyushu City holding the signed MoU

Meteorological observing station now installed close to the water tower of the former Chiran Airfield site (cultural heritage designated by the city) – right hand side in the fence

　The Tokyo National Research Institute for Cultural Properties (TOBUNKEN) and Minamikyushu City of Kagoshima Prefecture have jointly conducted research on conservation and restoration of individual cultural properties located in the city from around 2008. Now, we decided to conclude “MoU for Research on Conservation and Restoration of Cultural Properties Designated by Minamikyushu City” and explore further collaboration as joint research. Taking this opportunity, we conducted the conclusion ceremony of this MoU in the city office of Minamikyushu City on July 20th, 2022. At the ceremony, the project details were explained and SAITO Takamasa, Director General of TOBUNKEN and Mr. NURUKI Hiroyuki, mayor of Minamikyushu City signed them, after the explaining the project overview.

　Minamikyushu City has total 191 designated cultural properties. Among them, modern cultural heritage, including the buildings at the former Chiran Airfield site of the Imperial Japanese Army, as nation registered cultural properties and The Army Type-4 Fighter Aircraft, “Hayate”, a cultural property designated by the city are well known as mandatory materials in Japanese modern history. However, the modern cultural heritage’s characteristics differ from those of traditional cultural properties in volume, materials, functions, and others. Therefore, it often requires new methodologies for conservation and restoration.

　This joint research aims to solve technical issues related to conservation and utilization of these cultural properties, develop new conservation methodologies, vitalize research activities, and contribute toward promotion of public awareness of local cultural properties by collaboration of TOBUNKEN and Minamikyushu City. We will also provide information beneficial to other local governments who have the same or similar challenges by disseminating the research outcomes.