A document written on washi -- Japanese handmade paper -- was recovered from the Shosoin repository in Nara in legible condition. It dates to 702 CE, making it over 1,300 years old. Stone monuments erected in the same era have suffered worse deterioration. This paradox -- that paper can outlast stone -- is not poetic license. It is a material fact rooted in the fiber structure of washi, which gives it a tensile strength and flexibility that wood-pulp paper cannot match.
In 2014, UNESCO inscribed Japanese handmade washi on its Representative List of the Intangible Cultural Heritage of Humanity, recognizing three specific production communities: Hosokawa (Saitama Prefecture), Hon-Minoshi (Gifu Prefecture), and Sekishu-Banshi (Shimane Prefecture). Kyoto Prefecture's Kurotani village, while not included in the UNESCO designation, has produced washi continuously for approximately 800 years and remains one of the craft's most active production centers.
Why Washi Endures
The durability of washi is a function of fiber length. The primary raw material -- inner bark of the kozo (paper mulberry, Broussonetia papyrifera) -- yields fibers averaging 7 to 10 millimeters in length. By comparison, wood-pulp fibers used in industrial paper measure 1 to 3 millimeters. During sheet formation, these long kozo fibers interlock in a three-dimensional lattice rather than compressing into a flat, rigid plane. The resulting sheet is flexible, tear-resistant, and capable of absorbing and releasing moisture without structural damage.
This fiber architecture explains washi's extraordinary utility in conservation. The British Museum, the Louvre, the Smithsonian, and the Vatican all maintain stocks of Japanese washi for restoring damaged works on paper. When a Renaissance drawing tears, conservators bridge the tear with thin washi strips bonded with wheat starch paste. The washi fibers mesh with the original paper fibers at a microscopic level, creating repairs that are both structurally sound and nearly invisible. No synthetic material has been found to perform this function as effectively.
Two secondary fiber sources supplement kozo in the washi tradition. Gampi (Diplomorpha sikokiana), a wild shrub that resists cultivation, produces a silky, semi-translucent paper prized for woodblock printing and calligraphy. Mitsumata (Edgeworthia chrysantha), a cultivated shrub, yields a softer, more absorbent sheet used historically for official documents and banknotes. (Japanese paper currency was printed on mitsumata-blend washi until 1945, and the Bank of Japan still uses mitsumata fiber in its notes.)
The Production Process
Washi production follows a sequence that has remained largely unchanged since its documentation in the tenth-century text "Engishiki." The process is inherently seasonal: production runs from late autumn through early spring, when cold water temperatures inhibit bacterial growth that would weaken the fibers.
Kozo branches are harvested in late autumn after the leaves drop. The branches are steamed in large wooden vats for two to three hours, loosening the bark for stripping. Outer bark is peeled away first (reserved for coarser paper grades), followed by the pale inner bark -- the actual fiber source. This inner bark is soaked in running cold water for several days to soften it and wash out residual sugars and impurities.
After soaking, the bark is boiled in an alkaline solution for approximately two hours. Traditionally, the alkali came from wood ash lye; modern workshops typically use soda ash (sodium carbonate). This step dissolves lignin, hemicellulose, and other non-cellulosic components, leaving pure cellulose fiber. The boiled bark is then rinsed, inspected for remaining impurities (removed by hand with tweezers), and beaten on a stone slab with wooden mallets.
The beating stage is critical. Unlike industrial pulping, which shreds fibers into short fragments, hand-beating separates fibers without cutting them. The distinction determines paper strength: short fibers produce weak, brittle sheets; long fibers produce strong, flexible ones. An experienced papermaker beats kozo for 30 to 45 minutes per batch, gauging readiness by the fiber's appearance and feel.
The beaten fiber is suspended in a vat of cold water along with neri -- a viscous mucilage extracted from the roots of the tororo-aoi plant (Abelmoschus manihot). Neri performs a crucial function: it increases the water's viscosity, slowing drainage through the papermaking screen and giving the artisan time to distribute fibers evenly. Without neri, fibers clump and sheet formation becomes uncontrollable.
The Art of Sheet Formation
Sheet formation -- "nagashi-zuki" in Japanese -- is the stage where washi becomes a handcraft rather than a manufacturing process. The papermaker stands before a wooden vat, holding a hinged screen (su) constructed from thin bamboo strips bound with silk thread. The screen is dipped into the fiber suspension, scooped, and rocked in a rhythmic motion that distributes fibers across the screen surface in overlapping layers.
The rocking motion is the papermaker's signature. Each practitioner develops a personal rhythm -- a combination of forward-backward and side-to-side movements that cross-hatches the fibers for maximum strength. Three to four scoops build a single sheet. Excess fiber suspension is tipped off the far edge of the screen. The wet sheet is then couched (layered) onto a stack, separated by fine threads for later peeling.
Production rates vary by sheet size and thickness, but a skilled papermaker working full days typically produces 250 to 350 sheets of standard-size (roughly 60 by 90 centimeters) washi per day. Each sheet is formed individually. Each one is subtly unique -- imperceptible variations in thickness, fiber density, and translucency that constitute the material's handmade character.
After couching, the stack is pressed overnight to remove excess water. Individual sheets are then peeled from the stack and laid on wooden drying boards (traditionally smooth chestnut or ginkgo planks) in direct sunlight or a heated drying room. Drying takes several hours depending on conditions. The finished sheets are inspected, trimmed, and bundled for sale.
Washi in Kyoto's Cultural Ecosystem
Washi functions as a foundational substrate for numerous Kyoto crafts. Kyo-fusuma (Kyoto-style sliding door panels) use multiple layers of washi laminated with persimmon tannin for strength. Kyo-sensu (Kyoto folding fans) are constructed from washi stretched over bamboo ribs. Kyo-chochin (Kyoto lanterns) use thin, translucent washi glued to spiral bamboo frames. Gold-leaf folding screens -- among Kyoto's most iconic art objects -- begin with washi panels as the base layer onto which gold is applied.
Calligraphy paper represents another major use category. The interaction between brush ink and paper surface is central to the aesthetic of shodo (Japanese calligraphy), and experienced calligraphers select paper with the same deliberation a painter selects canvas. Kozo-based washi allows ink to penetrate and feather slightly along the fibers, producing the characteristic soft-edged brushstrokes valued in Japanese calligraphic tradition. Gampi-based papers, being less absorbent, hold ink on the surface for crisper, sharper lines.
A Craft Under Demographic Pressure
Japan's washi production volume has declined by approximately 90 percent since its mid-twentieth-century peak. The number of active washi workshops nationwide fell from roughly 600 in 1960 to fewer than 200 in 2024. In Kurotani, the youngest active papermaker is in their forties. The physical demands of the craft -- standing in cold water, beating fiber by hand, working through winter months -- present recruitment challenges that no amount of cultural recognition has resolved.
Yet the paper endures. Sheets produced in Kurotani today will remain functional for centuries. Museums will use them to repair works of art not yet created. The disproportion between the craft's fragile human infrastructure and its durable material output is perhaps washi's most remarkable characteristic: a product that outlasts the civilization that produces it, made by hands that cannot be replaced by machines.
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