Kozo Harvest in Ogawamachi
January 10, 2025
I recently took a trip to Japan to witness the harvesting of kozo to make washi. If you have ever wondered why handmade washi is so expensive, there is a lot of hand labor involved in making it.
Kozo refers to the Japanese mulberry tree, and it is a fiber that is used to make paper throughout Asia. The fibers of the inner bark are long, which makes it particularly suitable for water-based art mediums, as water can be absorbed throughout the depths of the paper. The kozo washi that is made in Ogawa is called Hosokawa-shi.
Kozo is a sustainable source of paper, which is harvested in the winter months. The branches are cut at the base of the bush and will regrow the following year, usually in a different place from where they were cut. In Ogawa, kozo is locally called “kazu” and the harvest is known as “kazu kiri”.
Once the branches are harvested, they are trimmed by hand on one end, and then cut to equal size (about 70 cm) with an electric saw. They are then stored in baths of water until they are ready to be steamed.
The steaming is done in order to peel the bark off of the branch. Branches are steamed with the wider end facing down in the caldron and then brought immediately into a room where the bark will be peeled away from the inner part of the branch. The branches are then discarded. In the past, farmers would do this job, as it gave them the chance to earn some income in their off-season.
Once the bark is peeled off of the branch, it is hung outside to dry, in order to prevent it from molding.
The bark is then soaked in water, and the outer dark brown and green layers of the bark are scraped off, leaving the inner white bark, which is the basis of kozo paper.
The white bark will then be boiled in soda ash, to soften it and to remove impurities. It is then rinsed, and bleached in the sun. During this process, the kozo is pulled apart by hand, and any impurities are removed.
