The Craft of Traditional Washi Papermaking

For well over a millennium, traditional Japanese papermaking, or washi, has occupied an esteemed position within East Asian artistic and scribal traditions. Unlike standard Western wood-pulp papers, which rely on shortened and chemically degraded cellulose fibres, washi is renowned for its remarkable tensile strength, flexibility, and longevity spanning centuries. These unique physical properties have made it indispensable not only for traditional calligraphy, woodblock printmaking, and architectural screens, but also in contemporary fine-art restoration worldwide. The durability of washi arises primarily from the choice of botanical raw materials—most notably the inner bark of deciduous shrubs such as kozo (paper mulberry), mitsumata, and gampi. Among these, kozo is the most widely utilised, prized for its exceptionally long, sinuous fibres that interlock tenaciously during sheet formation.

The manufacturing sequence begins during the winter dormancy of the shrubs, typically between December and February. Cultivators harvest one-year-old shoots, cutting them close to the base to encourage vigorous regeneration the following spring. Once gathered, the freshly harvested stems are bundled together and positioned vertically inside large steaming barrels set over boiling water. The steaming stage softens the resilient exterior layers, enabling artisans to peel the bark away from the inner woody core by hand in long, continuous strips. After peeling, these outer bark strips are hung across outdoor wooden racks to dry thoroughly, allowing papermakers to stockpile raw material for processing throughout the year.

When production resumes, the dried bark must undergo careful refining. It is first immersed in cold water for several hours to restore its pliability. Workers then meticulously scrape away the brittle, dark outer layer—known as the kurokawa—as well as the underlying greenish layer using curved steel knives. This labour-intensive peeling leaves behind only the pristine, creamy inner bast, referred to as shirokawa. To further purify and lighten this material without resorting to harsh chemical bleaches, the raw inner bark is traditionally subjected to natural weathering. In snowy mountainous regions, artisans lay the moist bast across fresh snowfields, where solar ultraviolet radiation and evaporating moisture generate mild hydrogen peroxide, naturally brightening the fibres.

The purified inner bark is next transferred to large iron cauldrons for cooking. This boiling process softens the tough cellulose bundles and removes non-fibrous substances such as pectins, starches, and lignin. Traditionally, artisans used a mild alkaline solution derived from wood ash, though modern practitioners sometimes substitute soda ash. Gentle cooking over several hours dissolves these cementing agents while leaving the delicate cellulose chain intact. Once the boiling phase concludes, the softened mass is immersed in running river water to rinse away residual chemicals. At this stage, artisans perform chiri-tori, a painstaking manual inspection in which residual specks of bark, discoloured fibres, and foreign particles are picked out by hand using small tweezers.

Having removed all impurities, papermakers proceed to the beating stage, which separates the coherent bundles into distinct, individual fibres. The material is laid out on heavy wooden blocks or stone slabs and pounded rhythmically with heavy oak batons or mechanical hammers. Unlike the industrial chopping mechanisms employed in Western paper mills, this traditional beating action flattens and separates the fibres longitudinally without fracturing their structural length. As the filaments disentangle, their microscopic fibrils fray slightly, creating tiny hooks that subsequently latch together when the paper forms, conferring extraordinary tear resistance upon the finished sheet.

The disentangled fibres are subsequently transferred to a large rectangular wooden vat filled with fresh cold water. To prevent the dense fibres from sinking or tangling into dense clumps, papermakers introduce a vital mucilaginous liquid called neri, extracted from the crushed roots of the tororo-aoi plant (a variety of hibiscus). Neri acts as a natural dispersant, coating the fibres, increasing water viscosity, and slowing the drainage rate through the screen. Using a specialised apparatus comprising a flexible bamboo screen positioned inside a hinged wooden frame, the papermaker performs nagashizuki, or the action of scooping the suspension, rocking the mould back and forth in rhythmic waves to intertwine the fibres across both axes, and tossing off the surplus slurry before water drains completely away.

Once a uniform layer of fibres settles across the screen, the artisan unhooks the wooden frame and carefully peels the wet paper layer away. The delicate sheet is transferred onto a stack, known as a post, with thin threads or edges offset to prevent adjacent layers from fusing. When the stack reaches several hundred sheets, it is subjected to gradual mechanical pressing over twelve to twenty-four hours to expel excess moisture without crushing the delicate fibre matrix. Finally, the damp sheets are separated one by one and brushed smoothly onto heated metal plates or planed pine drying boards, where they dry under ambient conditions or gentle heat. The finished washi is then inspected, trimmed, and sorted, ready to withstand centuries of artistic use.