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 The approaches to a variety of morphological information of historical documents and diaries have further deepened recently.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.