Japanese tissue

Japanese tissue is a thin, strong paper made from vegetable fibers. Japanese tissue may be made from one of three plants, the kozo plant (Broussonetia papyrifera, paper mulberry tree), the mitsumata (Edgeworthia chrysantha) shrub and the gampi tree (Diplomorpha sikokiana). The long, strong fibers of the kozo plant produce very strong, dimensionally stable papers, and are the most commonly used fibers in the making of Japanese paper (washi). Tissue made from kozo, or kozogami (楮紙), comes in varying thicknesses and colors, and is an ideal paper to use in the mending of books. The majority of mending tissues are made from kozo fibers, though mitsumata and gampi papers also are used.

The kozo plant is used in the manufacture of the following papers:

The gampi plant is used in the manufacture of the following papers:

The mitsumata plant is used in the manufacture of the following papers:

Japanese tissue paper is a handmade paper. The inner bark of the kozo plant is harvested in the fall and spring, with material from the fall harvest being considered better quality. Bundles of kozo sticks are steamed in a cauldron, then stripped of their bark and hung in the sun to dry. At this stage in the process, it is known as kuro-kawa, or black bark.

To make paper, the black bark must be converted into white bark. The stored black bark is soaked and then scraped by hand with a knife to remove the black outer coat. It is then washed in water and again placed in the sun to dry.

White bark is boiled with lye for about an hour, then left to steam for several more hours. At this point, it is rinsed with clear water to remove the lye. Then, it is stream bleached (kawa-zarashi). The fibers are placed in a stream bed around which a dam is built. Clean water is let in periodically to wash the fibers. Alternatively, the fibers may be bleached using a process called small bleaching (ko-arai). In this case, it is first placed on boards and beaten with rods before being placed in a cloth bag and rinsed in clear running water.

Impurities are removed after bleaching though a process known as chiri-tori. Any remaining pieces of bark, hard fibers or other impurities are picked out by hand or, in the case of very small pieces, by the use of pins. The remaining material is rolled into little balls and the balls are then beaten to crush the fibers.

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Wikipedia