|■Tokyo National Research
Institute for Cultural Properties
||■Center for Conservation
|■Department of Art Research,
Archives and Information Systems
||■Japan Center for
International Cooperation in Conservation
|■Department of Intangible
Lecture on basic chemistry using molecular models
Practical session for the selection of organic solvents
The Center for Conservation Science continues scientific research on the conservation and restoration of cultural property. Since FY 2021, based on our research, we have held workshops on basic science for conservators who have diverse experiences in the restoration of cultural property and museum curation and archiving.
In 2022, the workshop was held for three days from October 31st to November 2nd. We provided lectures and practical sessions on basic scientific knowledge essential for conservation and restoration, including basic chemistry, science of adhesion and adhesives, chemistry of paper, pest damage control, and usage and disposal of chemical agents. Researchers of the Tokyo National Research Institute for Cultural Properties delivered lectures based on their expertise.
We received 45 applications across Japan for 15 seats. In 2022, we invited 19 applicants from across Japan with varied backgrounds to the workshop; by contrast, in 2021, considering the COVID-19 pandemic, we accepted only those applicants who either resided in or commuted to Tokyo. Workshop content was carefully aligned with requests from the previous year. Participants expressed their appreciation for this workshop through the questionnaires provided. We received specific requests for disseminating scientific information used in actual conservation and restoration cases. We intend to continue this workshop series to meet these expectations.
Participants at the opening ceremony
In recent years, the investigations of conservation and restoration for cultural properties have expanded their targets not only to traditional cultural properties but also to modern artifacts and documents made of various types of materials. The Restoration Materials Section of the Center for Conservation Science invites experts from overseas and conducts workshops to meet these needs. In 2022, we invited Mr. Remy Dreyfuss-Deseigne, an expert who conducts research and application of nanocellulose films for conservation and restoration, to conduct a three-day workshop beginning on October 5th, 2022. Nanocellulose films are a kind of cellulose made from natural materials, which are transparent and stable. Therefore, nanocellulose films can be applied to transparent materials such as tracing paper and photo film with which traditional conservation materials do not work well.
We received applications more than double the official capacity of 15 seats for this workshop from conservators. This indicated high expectations for the workshop. We accepted all applicants to the lectures for the morning sessions, but we needed to limit participants for the practical sessions in the afternoon. The workshop began with an inauguration ceremony, with opening remarks by SAITO Takamasa, Director General of TOBUNKEN, and then the lecturer, Mr. Dreyfuss-Deseigne was introduced. During the workshop, the lectures were held in the mornings and practical sessions in the afternoons. On the last day, a tour of TOBUNKEN was conducted to see TOBUNKEN equipment related to the workshop.
This workshop with a lecturer invited from overseas was held for the first time in 3 years since the last one. The “face-to-face workshop” encouraged participants to raise very active questions and discussions. Participants said that they could build mutual collaboration among the workshop members. We recognized again the significant impact of in-person workshop, which could not be achieved online. We believe that our workshop helped in the actual reconstruction of cultural properties and conservation of archives.
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.
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.
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)
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.
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.
Conducting Research at the Okinawa Prefectural Museum & Art Museum
Fibers used in cultural properties come from a variety of sources including hemp, ramie, kudzu, and bashō (Japanese banana). As discussed in the May 2017 monthly report (Takuyo YASUNAGA, “Historical Position of ‘Hakubai-zu byobu’ by Goshun－A workshop is organized by the Department of Art Research, Archives and Information Systems”), we have learned in the more recent years that in addition to silk and paper, fiber is also used as the support medium in paintings. There are no well-defined, established methods of identification, however, in part due to the difficulty of discerning the characteristics of individual fibers once in textile state. Tokyo National Research Institute for Cultural Properties (TNRICP) is working to find a solution to these and other problems, in a cooperative research effort into fiber identification among the Department of Art Research, Archives and Information Systems; Center for Conservation Science; and Department of Intangible Cultural Heritage.
As a part of this research, the three-dimensional forms of fibers in a calligraphy work and a dyed article made of bashō-fu (textile woven from banana plant fiber) were examined using a digital microscope at the Okinawa Prefectural Museum from January 22nd to 23rd, 2019.
Bashō-fu is textile developed in Okinawa and Amami Islands and has been designated an important intangible cultural property, with Ms. Toshiko TAIRA recognized as an individual practitioner and Kijōka Bashō-fu Preservation Society recognized as a heritage protection organization. Of the work examined this time, the calligraphy work is known to have been created in a particular year and the dyed article is an item whose wearer can be guessed at. The examination showed that despite being all works thought to be made of bashō-fu, the look and the feel of the textiles varied due to differences in yarn density and yarn processing method.
While it is difficult to judge whether the differences are rooted in regional variation within Okinawa and Amami Islands or due to differences in use, we were able to conclude that many kinds of bashō-fu were created through different processes.
Accurate identification of fibers goes to the most basic data on a particular work, and is a key element in considering the circumstances of production. It is also a pressing issue in the organization of basic data for use in the present repair or the passing on to future generations of intangible cultural heritage.
We hope to continue furthering the research into identification of fibers through field investigations into techniques in conjunction with examination of exhibits at museums and art 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.
The lecture about solvents using molecular models
Practical work of removing stains on a painting
To conserve Japanese paintings, calligraphic works and other pictorial artifacts, we are now increasingly required to have some knowledge of conservation science. To meet these demands of conservators Tokyo National Research Institute for Cultural Properties and the Association for Conservation of National Treasures (ACNT) jointly conducted a workshop with a training program for conservators from July 31st to August 1st, 2018, which included lectures on basic knowledge and practical work sessions. The workshop aimed to provide hands-on knowledge that can be applied to actual conservation works. To achieve this purpose, we designed a curriculum that would help participants accurately understand the chemical properties of organic solvents and enzymes as well as the proper handling of basic laboratory instruments and chemicals for more effective and safer restorations. The workshop has been held once a year since 2016.
A total of 11 people, one from each corporate member of ACNT, participated in the workshop. Dr. Sano, Director of the Center for Conservation Science; Dr. Sato, Head of the Biological Science Section; and I provided lectures on the safe handling of organic solvents; integrated pest management (IPM) for cultural properties at restoration studios; and removal methods of adhesives and stains, respectively. Based on these lectures particularly using models of the molecular construction of solvents, the participants practiced removing various types of stains on the sheets of paper that we prepared, by using suitable solvents and enzymes. The practical work session also covered other topics such as the use of cyclododecane as a temporary protective coating for water-sensitive colorants. Mr. Kimishima, ACNT’s Senior Conservator, taught in the work session and provided hands-on training to the participants.
The program ended with a lively Q&A session and discussion. We will continue to hold such workshop in the future.
Lecture by Ms. Sano on the safe handling of organic solvents
Workshop by Mr. Kimishima on how to remove stains
To conserve Japanese paintings, calligraphic works and other pictorial artifacts, we are now increasingly required to have some knowledge of conservation science. To meet these demands of conservators who wish to learn how to handle chemicals, particularly those that have recently become more popular in restoration sites, and how to apply them in conservation and restoration works, the Tokyo National Research Institute for Cultural Properties and the Association for Conservation of National Treasures (ACNT) jointly conducted a workshop with training program for conservators from August 8 to 9, 2017, which included lectures on basic knowledge and practical work sessions. The workshop aimed to provide hands-on knowledge that can be applied to actual conservation works. To achieve this purpose, we designed a curriculum that would help participants accurately understand the chemical property of organic solvents and enzymes as well as the proper handling of basic laboratory instruments and chemicals for more effective and safer restorations.
A total of 11 people, one from each corporate member of ACNT, participated in the workshop. Dr. Sano, Director of the Center for Conservation Science; Dr. Sato, Head of the Biological Science Section; and I provided lectures on the safe handling of organic solvents; integrated pest management (IPM) for cultural properties at restoration studios; and removal methods of adhesives and stains, respectively. Based on these lectures, the participants practiced removing various types of stains on the sheets of paper that we prepared, by using suitable solvents and enzymes. The practical work session also covered other topics such as the use of cyclododecane as a temporary protective coating for water-sensitive colorants. Mr. Kimishima, ACNT’s Senior Conservator, taught in the work session and provided hands-on training to the participants.
The program ended with a lively Q&A session and discussion. We will continue to hold such workshop in the future.
Packing for transportation
The Tokyo National Research Institute for Cultural Properties (Tobunken) has been conducting the project “Work on the investigation of the preservation measures for Kitora Tumulus, a special historic site” since 2004. As the mural paintings in the tumulus required conservation treatments, it was decided that they would be removed from the tumulus and currently conserved externally. Three types of conservation treatments were conducted: maintaining the mural paintings in the tumulus, removing the mural paintings from the tumulus stone, and reconstructing the mural painting fragments. The removal of the mural paintings had been conducted for over 6 years, and the paintings were separated into 1143 fragments. The paintings have been reconstructed in the restoration facility in Asuka-mura, Nara prefecture. The Tobunken team has developed conservation techniques and performed experimental checks for this project, and the Association for the Conservation of National Treasures, an association of conservators for Japanese paintings, has applied the developed techniques.
On August 24th and 25th, 2016, three reconstructed mural paintings, the south wall with suzaku, west wall with byakko, and the ceiling with an astronomical chart were moved from the restoration facility to “Shijin no yakata”. This museum opened on September 24th, and the three mural paintings was exhibited for a month.
A lecture underway
A post-conference workshop
From April 8 to 10, 2015, a conference entitled “Adapt & Evolve: East Asian Materials and Techniques in Western Conservation” took place mainly at the Brunei Gallery at the University of London. The conference was organized by the Book and Paper Group of the Institute of Conservation (colloquially known as ICON) in the UK.
The conference consisted of tours of relevant institutions in the City of London, group events (presentations and question-and-answer panels), and various workshops. MASUDA Katsuhiko (an emeritus researcher at the Institute, currently a professor at Showa Women’s University), HAYAKAWA Noriko (a senior researcher at the Institute), and KATO Masato (a head of the Resource and Systems Research Section at the Institute) reported on the results of projects such as international training in Conservation of Japanese Paper (JPC) and the Cooperative Program for the Conservation of Japanese Art Objects Overseas as well as studies of the materials used to restore cultural properties. In addition, post-conference workshops were conducted after the conference. HAYAKAWA Noriko and KUSONOKI Kyoko (an associate fellow of the Institute) explained the traditional adhesives used in the field of conservation in Japan, and showed how to make starch paste and they instructed attendees in its application.
According to the conference organizer, the conference was attended by about 300 people from around the world. During the question-and-answer session, the conference chair asked the audience about the JPC, and the answer revealed that 30 or more individuals who had completed the training were in attendance. Individuals who had completed other workshops organized by the Institute were also in attendance. Thus, the Institute plays a major role in introducing East Asian materials and techniques to Western conservation. In addition, many of the attendees asked that the Institute continue to provide information about conservation.
Test application at Itsukushima Shrine
The Center for Conservation Science and Restoration Techniques conducts investigative research on restoration materials for cultural properties. Various types of restoration materials are needed in a diverse range of fields such as architecture, and fine and applied arts.
At Itsukushima Shrine, the center is involved in continuing investigative research on restoration materials for the large “Torii.” Itsukushima Shrine is located on the sea, in a severe temperature and humidity environment, directly exposed to wind and rain, and the effects of salts must also be taken into consideration. For such reasons, there are stringent conditions on the selection of restoration materials. Working time is also limited due to factors such as rise and fall of the tide. In selecting restoration materials, two types of testing are done in parallel: accelerated deterioration testing under various conditions in the laboratory, and exposure testing at the actual site.
Specifications of filling material were finalized through research studies up to the last fiscal year, and surface finishing materials are currently being studied. Based on the results achieved to date, test application of a selected material was carried out on October 22 and 23. Going forward, the center plans to make follow-up observations, and continue investigations to enable proper selection of materials.
Exposed test pieces under an open platform (stage)
The Center for Conservation Science and Restoration Techniques studied materials to restore the Otorii gate of Itsukushima Shrine. The study selected materials for use in a coastal setting with harsh conditions such as high temperature and high humidity, immersion in water, and the presence of salts. Forced degradation tests are currently being performed in the lab and an exposure test is being performed on-site. Exposure on-site began in June 2010, and the water content in test pieces is being measured and deterioration is also being observed, in every 2 months. These tests will continue in the future, and plans are to verify deterioration via a strength test in 2011. Forced degradation tests in the lab include a UV irradiation test and temperature cycle test, and plans are to conduct a salt spray test in 2011.
Inside the stone chamber with all plaster walls removed
The Center for Conservation Science and Restoration Techniques has been removing the wall paintings of Kitora Tumulus as part of a project called the Investigation on Conservation for special historic site Kitora Tumulus, commissioned by the Agency for Cultural Affairs. We had aimed to complete the removal in the next spring term following the intensive removal of the paintings in the spring and autumn of 2009. However, we removed all plaster from the stone chamber walls during this term earlier than the planned schedule (autumn 2010). This work was attributed to the proficiency of the engineers in removal, as well as to the development and improvement of the machines, tools and materials promoted by Tobunken. The work in the stone chamber was finished in a series of conservation projects of Kitora Tumulus Wall Paintings, starting with the removal of Seiryu (blue dragon) in 2004. We will begin treating and mounting the wall paintings in the conservation facility.
The damage caused by bark beetles and shipworms
The Center for Conservation Science and Restoration Techniques is also examining the extent of deterioration of wooden buildings in the project “Study on assessment of influence of ambient environment on cultural heritage and countermeasures.” Among the wooden buildings subject to a severe outdoor environment, particularly the Itsukushima Shrine in Miyajima-cho, Hatsukaichi City, Hiroshima faces stern conditions, such as harsh weather and the influence of seawater. It is affected by intense UV rays, wind, rain, seawater and waves, and was also heavily damaged by gribbles and shipworms under the sea. We are now studying how to prevent the wood from deteriorating in this situation, and how to restore the deteriorated wood and what restoration materials to use. Therefore, we are conducting physical tests such as a strength test, curing test and exposure test in various forms at the local site. In this way, we are investigating the optimum techniques to use. We hope that the results obtained by such examinations will be adopted for other wooden buildings.
Removing plaster on side wall
Removed plaster piece
The Center for Conservation Science and Restoration Techniques has been removing the mural paintings of Kitora Tumulus as part of a project “Investigation on Conservation for special historic site Kitora Tumulus” entrusted by the Agency for Cultural Affairs.
Following the first work of removing in May, we continued the work in two periods of three weeks each, from October 19 to November 6, and from November 16 to December 4. Although the work in autumn took longer than that in May, performing the removal over periods of three weeks each enabled efficient removal progress. All plaster on the ceiling was detached by this latest work, and we will be able to resume removal of the plaster on the side walls for the first time in two years. We will continue to inspect the in side of the tumuls periodically, while irradiating UV-C to control microorganisms, and conduct removal again next year.