Washi (和紙) is traditional Japanese paper. The term is used to describe paper that uses local fiber, processed by hand and made in the traditional manner. Washi is made using fibers from the inner bark of the gampi tree, the mitsumata shrub (Edgeworthia chrysantha), or the paper mulberry (kōzo) bush. As a Japanese craft, it is registered as a UNESCO intangible cultural heritage.
Washi is generally tougher than ordinary paper made from wood pulp, and is used in many traditional arts. Origami, Shodo, and Ukiyo-e were all produced using washi. Washi was also used to make various everyday goods like clothes, household goods, and toys, as well as vestments and ritual objects for Shinto priests and statues of Buddha. It was even used to make wreaths that were given to winners in the 1998 Winter Paralympics. Washi is also used to repair historically valuable cultural properties, paintings, and books at museums and libraries around the world, such as the Louvre and the Vatican Museums, because of its thinness, pliability, durability over 1000 years because of its low impurities, and high workability to remove it cleanly with moisture.
Washi is produced in a way similar to that of ordinary paper, but relies heavily on manual methods. It involves a long and intricate process that is often undertaken in the cold weather of winter, as pure, cold running water is essential to the production of washi. Cold inhibits bacteria, preventing the decomposition of the fibres. Cold also makes the fibres contract, producing a crisp feel to the paper. It is traditionally the winter work of farmers, a task that supplemented a farmer's income.
Paper mulberry is the most commonly used fiber in making Japanese paper. The mulberry branches are boiled and stripped of their outer bark, and then dried. The fibers are then boiled with lye to remove the starch, fat and tannin, and then placed in running water to remove the spent lye. The fibers are then bleached (either with chemicals or naturally, by placing it in a protected area of a stream) and any remaining impurities in the fibers are picked out by hand. The product is laid on a rock or board and beaten.
Wet balls of pulp are mixed in a vat with water and a formation aid to help keep the long fibers spread evenly. This is traditionally neri, which is a mucilaginous material made from the roots of the tororo aoi plant, or PEO, polyethylene oxide. One of two traditional methods of paper making (nagashi-zuki or tame-zuki) is employed. In both methods, pulp is scooped onto a screen and shaken to spread the fibers evenly. Nagashi-zuki (which uses neri in the vat) produces a thinner paper, while tame-zuki (which does not use neri) produces a thicker paper.
With enough processing, almost any grass or tree can be made into a washi. Gampi, mitsumata, and paper mulberry are three popular sources.
Until the early 20th century, the Japanese used washi in applications where Western style paper or other materials are currently used. This is partly because washi was the only type of paper available at that time in Japan, but also because the unique characteristics of washi made it a better material. The different uses of washi include: