Washi is extremely durable but lightweight paper.  Its  translucent beauty makes it a favorite printmakers, bookbinders, fine artists, and craftspeople.

Kozo, mitsumata, and gampi are the three most common fibers used for Japanese paper production, with kozo--a type of mulberry--by far the most popular. Compared with Western pulp, they differ most importantly in the length of the individual fibers--up to 12mm compared to less than 4mm for cotton rag pulp. These long fibers are kept suspended in the vat with the use of a slippery, viscous substance called formation aid, or neri. The predominant source of neri is the root of the Tororo-aoi plant, harvested at the same time as kozo.  

Thai kozo -- tan paper

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Neri production is relatively easy--just pound the Tororo-aoi roots and soak them in water. Preparation of the actual fiber takes more patience. After soaking, the outer bark of the plant must be removed; the black bark below and the underlying green bark must be scraped off with a knife. The white, inner bark--or bast--is dried, soaked again, and boiled in an alkaline solution which removes non-cellulose matter. After a thorough washing, and bleaching in the sun, final impurities are removed by hand. Finally, the fiber is formed into small balls ready for beating.  

Beating fiber for washi is a more delicate operation than the beating of Western fibers. Unlike cotton rag, kozo only needs a light beating to "tease" the fibers apart without tearing them. This is still done by hand, generally. If a Hollander is used, the roll and bedplate are brought close for only a short length of time, or not at all.  

Eastern and Western style methods of sheet formation differ greatly. The Japanese call the Western method tame-zuki which might be roughly translated as "the fill-and-hold way to make paper," since pulp is held in the mould until it drains and the remaining felted pulp forms the sheet. In contrast, the Japanese method is called nagashi-zuki and means something like "the flow-and-slosh way to make paper." The neri in the pulp allows for multiple dips into the vat, flowing in from the near edge and sloshing off the far side of the mould, in a continuous movement that keeps the pulp constantly moving. The number of times the papermaker dips the mould essentially determines the thickness of the sheet.  

The Eastern mould differs from its Western counterpart in that the deckle is attached with a hinge, and the screen is removable. This bamboo screen, or su, facilitates removing the sheet from the mould and couching it onto a post of finished sheets. Felts are  
unnecessary between sheets as the neri and long fibers allow the individual sheets to separate even after pressing. Each sheet is then carefully peeled off the post and brushed onto a smooth surface to dry.  

  Copyright 1997, Hand Papermaking, Inc.