Kozo (Paper Mulberry) Washi

The traditional Japanese washi — thin, strong, made from inner bark.

Texture

Translucent, very strong, long fiber

Yield

≈ 3 sheets per branch

Strip bark from mulberry branches, cook it soft, beat it to fibers, and form thin strong sheets.

▸Long strong fibers make paper that's nearly as tough as cloth.
▸This is washi — traditional Japanese paper.
▸A whole branch yields just a handful of sheets, but they last centuries.

Steps

01
Steam branches 1–2 hours, then strip the bark off in long ribbons.
02
Scrape off the dark outer bark, leaving the white inner bast fiber.
03
Cook bast fiber 2–3 hours in lye (or strong washing-soda solution).
04
Rinse and pick out specks by hand.
05
Beat fibers on a stone with a mallet for 30+ minutes until they fan apart.
06
Suspend in cold water with tororo mucilage; pull sheets with the bamboo su, layering wet sheets on a board.
07
Press overnight, then brush wet sheets onto smooth boards to dry.

Materials

— Fresh paper mulberry (kozo) branches
— Wood ash lye OR washing soda
— Mallet or wooden bat for beating
— Tororo-aoi root (or okra mucilage) as formation aid
— Su (bamboo screen) and keta (mould frame)

Safety

High Risk

Involves caustics, acids, or open flame. Full PPE and trained supervision recommended.

Hazards identified

Caustic alkali — burns skin, eyes, lungs

Quick checklist

☐Wear chemical splash goggles and nitrile gloves
☐Add alkali to water, never water to alkali
☐Keep vinegar nearby to neutralize spills
☐Work in a ventilated area; keep food and drink out of the studio
☐Read each material's safety data sheet (SDS) before starting
☐Have water, soap, and a first-aid kit accessible

Heuristic guidance derived from listed materials. Always consult each material's safety data sheet (SDS) and a qualified instructor before attempting.

Notes

Long fibers and mucilage are what make washi so thin and strong. Substitute okra slime if no tororo.