The Story of Japanese Textiles

The Story of Japanese Textiles


Hosoo was founded in 1688 and, for many years since, operated as a weaver. In 1923, the 9th head of the family, Tokujiro Hosoo, started the wholesale business of obi and kimono.

Today, the wholesale business has expanded and includes the curation of kimono culture and dyeing and weaving culture. As a curator, we research how dyeing and weaving cultures throughout Japan are interconnected and communicates the findings through our gallery and showroom.

Starting in 2015, we spent four years traveling from Hokkaido to Okinawa to visit 33 production sites of dyeing and weaving and to record the local culture nurtured by history and land. What we have learned ranges from each location’s natural environment, dyeing and weaving production process, people involved in dyeing, to unique materials and tools. Each of these elements contains a story about their local dyeing and weaving culture. So far, we have taken and archived over 20,000 photographs.

Tadeai (Persicaria tinctoria) in the buckwheat family, indoai (Indigofera su ruticosa) of the genus Indigofera in the pea family, Ryukyuai (Strobilanthes cusia) in the Acanthus family, and woad (Isatis tinctoria) in the mustard family-around the world, there exist techniques and cultures that use blue colorant “indigo” from various plants to dye fibers deep blue. Particularly in Japan, it is not an exaggeration to say that ai-zome (indigo dyeing) has been the most valued dyeing method since the spread of cotton farming in the early modern period. Atkinson, a chemist who came to Japan in the early Meiji period, was surprised to find so many Japanese people wearing blue garments and coined the term “Japan blue,” which is still in use today.

There are several methods for traditional ai-zome using tadeai, an annual plant of the genus Persicaria in the buckwheat family that used to be grown mainly in Honshu along the western part of the Pacific coast and in Shikoku and Kyushu, with its northern limit in the southern Tohoku region. The most popular is the aku-hakko-date (lye fermentation method).

Indigo, the colorant ingredient, is found in the leaf of tadeai as a transparent substance called “indican,” an indigo’s precursor. The leaves are harvested, dried, and fermented to produce indigo and then processed into preservable dye called sukumo. Because indigo does not dissolve in water or alcohol, to use it for dyeing, it needs to be fermented (a chemical change by microorganism action) again under an alkaline environment. By doing so, indigo is promoted to be transformed into water-soluble leuco indigo, which is applied to fibers and then exposed to the air to dye the fibers blue. The aku-hakko-date, which requires fermentation twice, is a technique unique to Japan. It fixes color well, and even when the dyed fibers are run through water multiple times, its color does not fade or migrate.

In the late Edo period, when the indigo dyeing was widely practiced, Awa Province (Tokushima Prefecture) produced the best, in quality and amount, ai (indigo dye) and sukumo. This is made possible by Awa’s fertile soil brought about by the flooding of the Yoshino River and long hours of sunshine. In anticipation of the flooding of the violent river known as Shikoku Saburo, the northern bank, where the indigo fields spread, was purposely built lower than the southern bank, where the castle town was located. At the house of Akihito Sato, who still produces sukumo in Awa no Kitagata (northern part of Awa), an evacuation boat is hung from the eaves, the tradition inherited by the family of sukumo makers.

The production of sukumo, which is still continued under Mr. Sato’s guidance, begins with the sowing of tadeai in early March and lasts for about ten months. The resulting sukumo is mixed with alkaline lye, bran and sake which become a nutritious source during fermentation, and wait to be fermented in a vat. As the fermentation progresses at a temperature between 25 and 30 degrees Celsius, tiny air bubbles form on the surface. This phenomenon, described as the “blooming of indigo,” is used as a way to judge the subtle condition of fermentation.

When soaking a yarn or cloth into the dye, the indigo-colored liquid briefly takes on a deep green color with a hint of gold. However, as soon as the tread or cloth is lifted and exposed to the air, the fibers instantly turn deep indigo.

About three or four months after planting tadeai, the first crop is harvested during the rainy season between late June and early July. After that, the sun-dried leaves are finely cut and stored. After nedoko (bed) is created, the fermenting process of the leaves (nesekomi) begins in early September, followed by a process of turning the leaves over (kirikaeshi). Just as toji (chief brewer) is responsible for making sake, ai-shi (indigo dye master) is in charge of the entire process of making sukumo. Ai-shi assesses the state of fermentation by looking at the condition of the tadeai, which has varying qualities from year to year, and makes precise judgments about the timing of kirikaeshi, which takes place 20 to 22 times in about 100 days, the amount of water, and the height of the pile. What influences the judgments are the smell, viscosity, and weight of the leaves. To understand the degree of fermentation and give correct instructions to the workmen, the ai-shi must hone the five senses and have many years of experience. Akihito Sato laughingly says that the secret is “to listen to the indigo’s voice. It sometimes resists, and other times it fights back. It’s like raising a child.”

Fermented indigo leaves emit intense heat. To make sure that the fermentation proceeds evenly, the leaves are stirred from the bottom and watered, which causes them to steam.
In Awa, to describe the fermenting of indigo leaves, they use the term nesasu (make them sleep), and the place the indigo leaves “sleep” to turn into sukumo is called nedoko (bed). The process of putting the first indigo leaves into nedoko, nesekomi, is conducted on Taian (the luckiest day in the Japanese calendar) in early September. The leaves continue to ferment, releasing heat and ammonia. Every fifth day, they are watered and turned over using a wooden rake. The process is called kirikaeshi. After kirikaeshi, the leaves are stored at the original height (about one meter). The amount of water and the height of the pile are said to determine the quality of sukumo, and the person in charge of watering and managing the pile is called mizu-shi (water master).
Under the direction of ai-shi, who is responsible for all aspects of making sukumo, the turned-over indigo leaves are piled up in a trapezoidal shape and then leveled. As fermentation progresses, the leaves heat up to about 70 degrees Celsius, and the smell of ammonia intensifies. As the leaves become sticky and clumpy, they need to be carefully loosened by kirikaeshi.
When the temperature drops in mid-October, the temperature needed for fermentation is maintained by covering sukumo with a straw mat called futon. Each time kirikaeshi is carried out, the top and sides of trapezoidal-shaped sukumo are thoroughly covered with the straw mats, which are fixed firmly with straw rope. It is one of the required processes for the fermentation of sukumo.
After fermentation, sukumo is packed in bags called kamasu and shipped nationwide, about six months after the harvesting of the indigo leaves.
To do ai-zome, the fermented indigo leaves, sukumo, need to be fermented one more time. The second round of fermentation is called ai-date. As the indigo continues to ferment in the jar, fine air bubbles start to form on the surface when it is stirred. These bubbles are called “indigo flowers.”
A bundle of silk yarn is soaked in an indigo jar, pulled up, and squeezed tightly. By repeating this process over and over, the indigo color permeates into the yarns. When squeezed, the color of the yarns is almost greenish-blue, but when the tension is loosened, and the yarns are exposed to the air, the colorant component indigo oxidizes, and the yarns suddenly turn indigo blue.
Text: Masae Inoue
Cooperation: Akihito Sato, Hidenori Nakanishi (Honaizome Miyabiori Kobo)

Zenjiro Tamura and Chiharu Miyamoto (editorial supervision),
Miyamoto Tsuneichi to aruita Showa no Nihon 21: orimono to somemono
(Japan during the Showa period explored on foot with Tsuneichi Miyamoto 21: textile and dyeing), Rural Culture Association Japan, 2011

Nihon Aizome Bunka Kyokai (editor),
Nihon no ai: densho to souzou (Japanese indigo: tradition and creation),
Nihon Hoso Shuppan Kyokai Publisher, 2002

Nihon Aizome Bunka Kyokai (editor),
Nihon no ai: someori no bi to dento
(Japanese indigo: beauty and tradition of dyeing and weaving),
Nihon Hoso Shuppan Kyokai Publisher, 1994
All photos by Kotaro Tanaka