Takashima, Akihiko
University of Tokyo. Historiographical Institute. Engineer in the Conservation Laboratory
Shibutani, Ayako
University of Tokyo. The University Museum. Specially-appointed Researcher
Surveys of historical paper materials for conserving original resources and their conservation methods
This paper examines the survey results of historical paper materials and their methods for conserving original resources at the Historiographical Institute of the University of Tokyo (HI; Shiryo Hensan-jo in Japanese).
At the University of Tokyo, original resources are mainly treated as book collections at libraries including the general library, faculties' library, and institutes' libraries, and categorised as valuable books or originals. These resources have been used for education and research materials and shown as cultural properties from the viewpoint of their scarcity value. In so doing, they are now required to manage new conservations and surveys. In any conservation survey—especially in surveys of the paper itself as the base material of the original resources—microscopic observations are usually conducted. In the preliminary studies by Masahiro Tomita, Ken’ichi Yuyama, and Akinori Okawa, a small mobile microscope with 100 times magnification was used for examining the thickness and density of fibres, the existence and quantity of additives such as rice powder and kaolin, and the conditions of other materials like plant parenchyma. These surveys are essentially non-destructive, and Tomita’s group presented their own standard for distinguishing paper materials accurately. In recent years, USB digital cameras for microscopy and lenses of megapixel cameras have rapidly been upgraded, and researchers are able to gain distortion-free and high-definition images easily.
As to the field of scientific studies of cultural properties, analysing methodologies in archaeology and botany are applied to identify rice powder and plant parenchyma as additives used in paper-making, and to measure their contents. The approaches to a variety of morphological information of historical documents and diaries have further deepened recently. Based on these research situations, we along with the HI, are conducting a multilateral approach to components of historical paper materials such as fibres and starch grains. In this paper, we focus on sharing our research results and future perspectives.
原本史料保存のための料紙調査とそれに基づく修理手法
本報告では、東京大学史料編纂所における古文書等の原本史料保存のための料紙調査と、それに基づく修理手法について述べる。
東京大学では、原本史料は図書館・図書室・研究室で蔵書として位置付けられ、貴重書・原本類として分類される。これらは教育研究材料としてだけでなく、その希少価値から文化財としての性格を帯びてきた。そのため、新たに修理方針と調査を進める必要がある。修理の調査、特に原本史料の基底材である料紙の調査では、顕微鏡を用いた分析が行われる。富田正弘・湯山賢一・大川昭典諸氏たちの先行研究では、100倍率の小型携帯顕微鏡を用いて、繊維の太さと密集度、米粉や白土等の添加物の有無と含有量、植物の柔細胞などの物質の残存状況を非破壊観察によって検討し、より精度の高い料紙の識別基準を提示した。近年は、顕微鏡用USBデジタルカメラやメガピクセル対応カメラレンズの機能が急速に向上し、ゆがみの少ない非常に高精細な画像の撮影が可能となった。
一方、文化財科学の分野では近年、考古学や植物学の分析手法を応用し、料紙の製造過程で添加された米粉や植物の柔細胞の特定、含有量の計測が実践されており、古文書や古記録の多様な形態情報に関する研究はさらに深化してきている。これらをふまえ、東京大学史料編纂所および報告者たちは、繊維やデンプン等料紙の構成物に対する多角的な研究を進めている。今回の報告では成果と課題を共有したい。