Paper: a Chinese invention that took a thousand years to reach Europe

Paper is made by breaking plant material down into individual fibres, suspending them in water, catching a thin layer of them on a screen, and drying it. The fibres bond to each other as they dry without any adhesive, through hydrogen bonding between cellulose molecules.

That is the entire principle, and everything else is variation on it.

The route west

Paper-making is attributed to China, with the traditional date placed in the early second century, though archaeological finds of paper predate the conventional attribution.

It spread to Korea and Japan by the early seventh century, where it developed into distinct traditions using different fibres. It moved west along Central Asian trade routes, reaching the Islamic world by the eighth century — Samarkand and then Baghdad became major centres — and from there through North Africa into Iberia.

The first paper mills in western Europe appear from the twelfth and thirteenth centuries. So the technology took roughly a thousand years to travel from its origin to western Europe, which is a useful corrective to any assumption that useful technologies spread quickly.

The fibre determines everything

Different traditions used what grew locally, and the resulting papers are barely comparable.

Bast fibres — the inner bark of certain shrubs and trees — produce long, strong fibres. Japanese washi uses kozo, mitsumata and gampi, and the resulting paper is extraordinarily strong for its weight, translucent, and durable enough that it is used to repair centuries-old documents in conservation studios worldwide.

Bamboo was used extensively in China, producing a softer, more absorbent paper suited to brush writing.

Linen and cotton rags were the European raw material for centuries. Old textiles were collected, sorted, retted and beaten into pulp. The resulting rag paper is very stable and it is why documents from that era survive in better condition than many from the nineteenth century.

Wood pulp, from the mid-nineteenth century, made paper cheap and made it acidic. Lignin remaining in mechanical wood pulp degrades and produces acid, which is why newsprint yellows and crumbles. A great deal of nineteenth and twentieth-century printed material is in worse condition than material three hundred years older, which is an ongoing problem for archives.

The process, in outline

Preparation. Harvesting, stripping bark, removing the outer layer, and steaming or cooking with an alkali to break down the material that binds the fibres.

Beating. Mechanically breaking the material into individual fibres and roughening their surfaces so they will bond. Done by hand with mallets in older traditions, later by water-powered stampers and then by mechanical beaters. This step largely determines the character of the paper — longer beating gives denser, harder, more translucent sheets.

Forming. A screen is dipped into a vat of fibre suspension and lifted, catching a layer. The technique differs fundamentally between traditions.

The European method takes one dip and lets the water drain, giving a random fibre orientation. The Japanese method involves repeatedly rocking the suspension across the screen, building up layers with the fibres aligned, which is why the paper is so strong. A formation aid from a plant mucilage is used to keep the long fibres suspended.

Pressing and drying. Sheets stacked with felts and pressed, then dried on boards, on heated surfaces, or in the air.

Sizing, where required, to stop ink spreading — with gelatine, starch or plant extracts depending on tradition.

Paper as more than a writing surface

In several traditions paper is a structural material. Japanese architecture uses it in sliding screens, where its translucency and strength do real work. Paper has been used for clothing, for rope, for umbrellas, for lanterns and, treated with oil or lacquer, for waterproof goods.

Paper cutting, folding and pasting traditions exist across many cultures, from Chinese and Mexican cut-paper work to the various folding traditions. These are not marginal decorative practices; in several cases they are central ritual crafts.

The state of the craft

Industrial paper is enormously cheaper and it is fine for nearly every purpose, so handmade paper survives in the places it always survives: conservation, art, ritual and luxury.

Conservation is the interesting one, because it is a genuine functional requirement rather than a preference. Repairing an old document needs a paper that is chemically stable, thin, strong and reversible, and handmade papers from certain traditions remain the standard material. That has kept several workshops in continuous operation for reasons that have nothing to do with nostalgia.

Elsewhere the pattern is familiar: an ageing group of makers, few apprentices, and a craft that requires years to learn and pays poorly. Where the traditions have survived it is generally because a government, an institution or a market for artists' materials decided they were worth funding.