The workshop sits on the bank of a small river an hour northwest of Tokyo. In winter it is roofed by snow. In summer the cicadas are loud enough to interrupt conversation. Akiko Tateishi, sixty-eight, has worked here since she was twenty.

Her kozo, the paper mulberry whose inner bark is the fibre of washi, grows on a quarter-hectare she rents from a neighbour. She cuts the shoots herself in December when the leaves have fallen and the sap is low.

The cut shoots are steamed for two hours in a wooden barrel over an oil drum fire. The bark, loosened by the steam, peels off in long ribbons. She works barehanded and quickly, while the bark is still hot.

The outer black bark is scraped off with a small steel knife on a wet board, leaving the white inner bark. This is the part that becomes paper. A morning's bark-stripping yields about three kilograms of usable fibre and several blisters.

The white bark is dried on bamboo poles outside the workshop and stored in paper bags until needed. Tateishi sheets paper only between January and April, the months her teacher told her had the cleanest water.

Cooking the bark happens in a copper cauldron with wood ash lye, simmered for three hours. The fibres soften and the remaining bits of bark dissolve. She rinses the cooked fibre in running river water for a full day.

“Cooking the bark happens in a copper cauldron with wood ash lye, simmered for three hours.”

Beating is done by hand, on a granite slab beside the river, with a hardwood mallet whose head is the size of a man's fist. She beats for about forty minutes per batch, turning the fibre repeatedly until it splays into a fine fluff.

She owns a small mechanical beater that her son installed in 2014. She uses it for ordinary commissions. For the papers that matter to her, she still uses the stone and the mallet.

The vat is a wooden tank lined with tile, about waist height, fed by a pipe from the river. Into it she pours the beaten fibre and a viscous mucilage made from the roots of the tororo-aoi, a plant she also grows behind the workshop.

The mucilage is what allows the fibres to suspend evenly in the water and what gives washi its strength. Tateishi grates the roots into cold water and strains the slime through silk. The slime is added a ladle at a time, judged by how the vat thickens.

Sheeting is done with a bamboo screen called a sukibune, mounted in a wooden frame. She dips the frame into the vat, lifts a thin layer of fibre, shakes it with a particular wrist motion to interlock the fibres, then dips and lifts again to build the sheet.

A sheet of standard washi takes about thirty seconds to form. She makes between three and four hundred sheets in a working day. Her hands, by March, are red and cracked from the cold water. She wears no gloves.

The wet sheets are stacked, one on top of the next, separated by nothing. The mucilage allows them to be peeled apart later without sticking. The stack is pressed overnight under a weighted board to expel water.

Drying is done on cedar boards in the sun. Tateishi brushes each wet sheet onto a board with a wide horsehair brush and leaves it until the sheet releases itself, which takes about an hour on a clear day.

Her papers go to calligraphers in Kyoto, to a sliding-door maker in Kanazawa, and to a small group of book conservators in Europe who use her thinnest sheets for mending. She knows most of her customers by their handwriting on the order forms.

She trains one apprentice at a time. The current apprentice, a woman from Sendai named Mariko, has been with her four years. Tateishi expects she will be ready to make her own paper in another three.

The river behind the workshop runs clear in spring, milky in autumn, and freezes at the edges in January. The vat is filled each morning with the same water her teacher used, which her teacher's teacher used, and which, Tateishi hopes, Mariko's apprentice will use one day in turn.