Investigation for Sustainable and Stable Supply of Noriutsugi
Neri is extracted from noriutsugi bark. The yellow part of the tree is where bark has been removed.
Washi (Japanese traditional paper) is used for the restoration of cultural properties and for traditional crafts. It is well known that washi is made of fibers extracted from plants such as kōzo (Broussonetia kazinoki x B. papyrifera) and ganpi (Diplomorpha sikokiana). However, it is not widely known that neri, a dispersant, is also essential for washi making. Adding neri disperses the fibers evenly in water, producing smooth and beautiful washi. Without the addition of neri, the fibers are not evenly dispersed, and washi made without neri has poor formation.
Including washi most cases of industrial mass paper manufacturing use synthetic compounds such as polyethylene oxide as neri. Traditionally, neri is made from mucilage extracted from plants such as tororoaoi (Abelmoschus Manihot) and noriutsugi (Hydrangea paniculate). At present, neri extracted from tororoaoi or noriutsugi is still most suitable for thin washi making. It is also widely used for washi-making for cultural property restoration. However, the sustainable and stable supply of these raw materials, especially noriutsugi, becomes increasingly difficult. This is because noriutsugi for neri is a wild species and there are not enough successors to the experts with knowledge on locating noriutsugi and removing its bark. If the low amounts of noriutsugi available does not change, this will permanently impair washi-making for the restoration of cultural property. For example, uda washi paper used for soura-kami (the final lining paper) of hanging scrolls is made using neri extracted from noriutsugi. Therefore, we are concerned that restoring hanging scrolls will become difficult in the near future.
Commissioned by the Agency for Cultural Affairs, the Center for Conservation Science has been conducting a research project: “Investigation of Tools and Materials Used for the Preservation and Restoration of Fine Arts and Crafts” with the Department of Art Research, Archives and Information Systems and the Department of Intangible Cultural Heritage. As an important investigation of this project, we are working for sustainable and stable supply of noriutsugi. This investigation is conducted in cooperation with Hokkaido Prefecture, Shibetsu Town and others. We visit the noriutsugi growing area in Shibetsu Town and hold regular discussion meetings. We will provide supports for sustainable and stable supply of noriutsugi and conduct scientific studies on why neri extracted from noriutsugi shows such excellent characteristics.