Indigo turns up on a trip to Tokyo in small ways: a noren curtain over a doorway, a tenugui hand towel at a craft counter, a bolt of heavy cloth whose tag says aizome, the Japanese word for indigo dyeing. The tag is doing more work than it appears to. One word is standing in for a plant, a fermentation, a colour that only appears once cloth meets air, and a trade with roots in Tokushima's river fields and in an Edo dyers' town.
This article separates those things. It is not a growing guide and it is not a dyeing recipe. It is for a traveller who wants to look at a blue cloth and know what question to ask of it, and it sits inside a wider guide to a quiet trip to Tokyo.
This is one thread in a wider story. The free guide Japanese Aesthetics Unveiled follows a similar way of looking, through art, architecture and cultural heritage.
Three different things share the name. The first is a plant. Japanese indigo is Persicaria tinctoria, a member of the buckwheat family, which Wikipedia's entry on the species records as native to southern China and Vietnam and introduced to Japan. A peer-reviewed fact sheet from Utah State University Extension says it likely reached Japan from China, and that textiles dyed with it in Japan date back to the late 700s.
The second is a dye, and the leaf is not the dye. The same fact sheet explains that the plant contains indican, the chemical precursor to the indigo pigment. Wikipedia's entry on indigo dye describes the difficulty that follows: the pigment does not dissolve in water, so it has to be chemically reduced to what is called white indigo before cloth can take it up. When a submerged fabric is lifted out of the bath, the white indigo combines with oxygen in the air and reverts to the intensely coloured pigment.
The third is a colour, and it arrives last. Tokushima Prefecture's page on Awa indigo says that cloth is immersed in the dye liquid and aired, that the pigment then reacts with oxygen and is fixed, and that after the cloth is washed well in water a vivid indigo colour appears. JNTO's article on aizome, from the Japan National Tourism Organization, says that in its handkerchief demonstration at a Tokushima museum the cloth is still a deep green after its final dip and turns a vivid indigo blue when it is washed in water. The blue appears in the air and the rinse.
A natural first question is: what is the dye from an indigo plant called? The dye from the indigo plant is called indigo. In Japanese it is ai, and aizome is the traditional practice of dyeing with it. Tokushima Prefecture adds that sukumo, made from the plant's dried and fermented leaves, is the natural dye, and that sukumo produced in Tokushima is called Awa-ai, a name JNTO ties to the old province of Awa.
The step between plant and vat is easy to miss. Tokushima Prefecture says the leaves ferment under careful temperature control for approximately 100 days in facilities called nedoko, literally beds. JNTO's 2020 article profiles Kenta Watanabe of Kamiita, Tokushima, one of very few remaining aishi, dyers who make their own dye, and in that profile the whole process from planting to dye takes one year.
Turning sukumo into dye is a second fermentation. JNTO says sukumo rests for three more months and is then mixed with natural wood ash, sake and wheat bran, creating a highly alkaline environment that activates microorganisms. The prefecture describes mixing with alkaline substances such as lime and wood ash lye and fermenting for a week. Watanabe says the quality of the sukumo determines how vivid the blue turns out.
The accounts differ on the ingredients. The Nihon Minkaen museum in Kawasaki, which runs an indigo workshop, lists lime, ash water and water, heated and fermented into a solution. Wikipedia describes the older Japanese method as a heated vat holding a culture of thermophilic, anaerobic bacteria. What stays constant across the accounts is fermentation.
The first thing to know about judging indigo cloth is what the label cannot tell you. JNTO states that chemical dye is now used for many indigo products, and it describes aizome as indigo-dyed clothing made with natural dye. An indigo label therefore shows that indigo was involved somewhere, and says nothing about the process behind it. JNTO puts the share of dyed indigo products made with dye from natural lye fermentation at less than one percent of the world's total, a figure it gave in 2020.
The Nihon Minkaen museum's price list for dyeing a visitor's own cloth shows the same question in miniature. It offers two options, regular indigo and natural indigo, with no explanation of how they differ. Which indigo is a question the cloth cannot answer for itself.
Watanabe makes a claim about why the difference matters, and it is a maker's claim, not a laboratory result. He says natural dye penetrates deep into the fibres of the cloth, so the colour is less likely to fade over time. It is worth carrying that sentence into a shop as a question rather than as a fact: how was this dye made?
The second check is the pattern. JNTO's short vocabulary of aizome techniques doubles as a set of questions about how a design was made. In shibori, the fabric is gripped, tied or folded during dyeing, leaving undyed white patches. In danzome, artisans dye the fabric in stages, shifting its position as it is dipped, to produce a gradation of shade. In bassen, the fabric is first dyed uniformly with indigo, and a stencil and a chemical are then used to lighten areas of the finished cloth.
Set side by side, the shibori and bassen descriptions give a reader one practical question for a pale pattern on a dark ground that might be either of these: was the pale kept out of the dye by tying or folding, or taken out afterwards? The question does not rank one method above the other. It tells you what you are looking at, which is the part a label leaves out.
Blue jeans are the nearest familiar object for comparison. Wikipedia's entry notes that most indigo dye produced today is synthetic, about 80,000 tonnes a year worldwide as of 2023, and that it is most commonly associated with denim and blue jeans. What aizome adds to the comparison is the process, not the colour name.
What colour is indigo dye in Japan? A range of blues, from pale to deep. JNTO says that repeating the one-minute dip and air-dry around 30 times brings out an intense shade of indigo called kachiiro.
Tokushima Prefecture names several shades: kamenozoki, the pale colour seen when you peep into a tub of indigo dye liquid; hanadairo, light blue; aiiro, indigo blue; and kachiiro, a "winning color" that samurai warriors once wore because its name is a good omen for winning.
The Nihon Minkaen museum describes the colour of indigo dyeing as deeper than sky blue and lighter than navy blue, a reminder that "indigo" names a range of blues rather than one point.
For a visitor, that turns a flat compliment, "what a lovely blue", into a question worth putting to a maker: what is this blue called, and what was done to get it? The label will not answer that, and the colour alone does not either.
Why did indigo matter so much in Edo-period Japan? Two accounts give part of the answer, and neither is about taste: one explains why Awa indigo prospered, the other why demand came from commoners. The first comes from Tokushima Prefecture's own history of Awa indigo. It says the origin of Awa indigo is not certain, and that the earliest record it cites is a 1445 shipping tax ledger from Hyogo that lists indigo being shipped. Production increased between the Edo and Meiji periods, 1603 to 1912, and Awa indigo dominated the national market in the 1700s.
The prefecture gives three reasons for that prosperity: cotton, which goes with indigo, began to be cultivated around Osaka and raised demand; the Tokushima domain promoted and protected the business; and the topography and climate suited the crop.
JNTO tells a similar story with a different age. It says aizome in Tokushima dates back nearly 800 years, that indigo production proved lucrative for the area in the 16th century, that the government of the time protected the land and encouraged production, and that more than 2,000 farmers were involved in growing and processing the dye at the peak. The two pages give different pictures of its age: JNTO says nearly 800 years, while the prefecture says the origin is uncertain and offers 1445 as the earliest record it cites.
The second account explains why the demand came from ordinary people. Wikipedia's entry on indigo dye says that indigo became especially important in Japan during the Edo period because of a growing textile industry, and because commoners had been banned from wearing silk. That ban led to more cotton being grown, and so to more indigo, which the entry calls one of the few substances that could dye it. On that account, a rule about what commoners could not wear led to a crop that needed indigo.
Tokyo's connection to indigo is written into a place name. The National Diet Library's entry on Kanda Konya-cho (神田紺屋町) describes a town ruled by the dyer Tsuchiya Goroemon, whom Tokugawa Ieyasu allowed to buy Japanese indigo plants from the Kanto region and Izu from the Keicho era, 1596 to 1615. Many indigo dyers lived together there, and the river that flowed nearby was called the Aizome-gawa, the indigo-dyed river.
Nakamura tells a separate story in our interview. He says that when people settled in Nihonbashi, that was where things were made, and that as the peaceful era went on and the population grew, the Kanda River became polluted with wastewater while demand for kimono kept rising. Craftsmen needed more space and clean water, so they walked upstream along the river and found the places now known as Waseda, Takadanobaba and Ochiai, in Shinjuku. The interview's editors add that Shinjuku Ward still designates dyeing as one of its local industries.
The Diet Library entry describes an Edo town of indigo dyers. Nakamura is speaking about kimono craftsmen in general, not about indigo dyers. Put together, the two accounts say something narrower: the Diet Library places indigo dyers beside a waterway in Edo, and Nakamura says Tokyo's kimono craftsmen later followed clean water upstream to Shinjuku.
Episode 1 of our film series with Nakamura covers how brush-dyeing travelled from Kyoto to Edo. It is a film about hikizome, not about indigo.
A caution comes first. Fujiya Dyeing Studio (ふじや染工房), the Shinjuku workshop in our interview with Takatoshi Nakamura, is not an indigo workshop. It specializes in hikizome, brush-dyeing, and its core job is ground-dyeing for Tokyo hand-painted yuzen artists, work it has done since the studio was founded in 1952. It belongs in this article because of what Nakamura says about colour.
Nakamura says the Edo-style hikizome of his studio "isn't about the kind of brilliance you find in Kyoto" and is instead "restrained, understated, and yet it still manages to look sharp." Describing the bokashi technique, he says:
"Rather than using many colors like a rainbow, expressing the iki of Edo means putting many colors — or rather, depth — inside a single blue, for instance. That's when I use the bokashi technique."
— Takatoshi Nakamura, third generation of Fujiya Dyeing Studio
Iki, Nakamura says, is "a refined, understated elegance particular to Edo-period townspeople's aesthetics, a beauty that reveals itself gradually rather than announcing itself." His phrase for the colour is hedged: "a single blue, for instance." Blue is his example, not his rule, and bokashi, a gradation within one colour, is the technique he names for it. The interview's editors add that there were periods in the Edo era when sumptuary edicts restricted flashy dress, and that within that constraint the ability to find layer upon layer of expression within a single colour was sharpened.
A concrete example comes from the studio's own work. For a Wall Art Textile on the fourth floor of a Tokyo hotel in Shinjuku, Nakamura says he designed a woven pattern around the image of a flowing river, used blue tones evoking water, and dyed it with bold bokashi gradation. The interview does not say which dye produced those blues.
Nakamura's depth is made with the brush and bokashi gradation: a single pass of the brush, the interview's editors say, can create gradation across the fabric. The Tokushima method JNTO describes builds depth by repetition instead. The processes differ, but our reading is that the question carries over. In front of a plain-looking cloth, ask how much depth one colour holds, not how many colours it has.
Colour made to order is also a workshop habit elsewhere in Tokyo. In our article on kumihimo, the Ueno workshop Domyo dyes an estimated three to four thousand colours a year, because an obi-jime, the cord that ties the sash, has to sit against a specific kimono and a specific obi rather than against a palette.
The turning point came from outside. Wikipedia's entry on indigo dye records that BASF developed a commercially feasible manufacturing process for synthetic indigo that was in use by 1897, when 19,000 tons of indigo were still being produced from plant sources. By 1914 plant-sourced production had dropped to 1,000 tons, and by 2011 about 50,000 tons of synthetic indigo were being produced worldwide. Those are world figures, not Japanese ones.
Tokushima's own numbers come from the prefecture. Its indigo cultivation area reached a peak of approximately 15,000 hectares in 1903. After that, imports of precipitated indigo from India and synthetic indigo from Europe grew, and Tokushima's production volume plummeted. Tokushima's peak came six years after the 1897 process, and the plunge followed.
The question that follows is who kept the vat going. JNTO describes Watanabe as one of very few remaining aishi and as one of only a handful of artisans who do everything from growing the plants to making the dye, designing the products and selling them. The artisans of Kamiita, it says, strive to keep the traditional technique of lye fermentation alive.
That gives the plain answer to a question a careful buyer should ask: is natural Japanese indigo dyeing still made the traditional way? Yes, but it is rare. JNTO reported in 2020 that fewer than one percent of the world's dyed indigo products are made with dye from natural lye fermentation, a world-wide figure and not a Japanese one, and that artisans in Kamiita, Tokushima, work to keep that method alive. Tokushima Prefecture adds that Awa indigo is still produced there by indigo dye artisans who are passing on the tradition, and that the beauty and natural texture of natural indigo have been re-evaluated.
Whether synthetic indigo counts as real aizome depends on what the word is asked to cover. Wikipedia records that a synthesis reported in 1890 produced a blue compound chemically identical to natural indigo. JNTO, for its part, describes aizome as indigo-dyed clothing made with natural dye. Both statements can hold: one is about the molecule, the other about the process behind the cloth.
Three levels of access are worth knowing. The first costs nothing but attention. Anyone can look at indigo cloth in a museum collection or on a shop shelf, and the label question and the pattern question work in both places.
The second level takes a deliberate trip. The Nihon Minkaen museum's Traditional Indigo Dyeing Workshop, in its Dento-Kogeikan building in Kawasaki, offers individual indigo dyeing. The museum's own description of the workshop says prior reservation is required and that the instructions at its lectures and workshops are mostly in Japanese. In Tokushima, JNTO says the dyeing experience at the Ai no Yakata museum takes no reservations, lasts about twenty minutes and comes with guidance in English, while Watanabe's factory can be visited by online reservation. JNTO also notes that Tokushima is about a 70-minute flight from Tokyo, which makes it a separate decision from a Tokyo itinerary.
A third level would be a studio with no public programme, where a visit would have to be arranged. For indigo, that third level is our inference.
Knowing that levels exist is itself useful. One Tokyo silversmith workshop shows a similar idea, in a pattern that runs from a public story to a hands-on session and beyond.
In Tokushima, JNTO's 2020 article describes one maker, Watanabe, as meticulous about going beyond the framework of traditional culture to make aizome products that suit modern life.
In Tokyo, our Shinjuku interview shows a dye house changing in a different way. Three generations are now involved in the workshop: Nakamura and his father handle everything from mixing colours to dyeing, his son, about a year into training, is learning by watching, and his mother handles customers, steaming and machine sewing. The postwar work was volume, thirty or forty bolts dyed in one colour at a time, and it shifted toward one bolt in one colour for a known customer as kimono demand declined.
About four years ago, Nakamura says, it became clear that the old way of working would not be sustainable. People were wearing kimono dyed by his studio, yet the studio's name appeared nowhere, so he moved toward making its own products and services and stepping forward himself. The studio also runs a hands-on programme for visitors in which participants choose a colour they like, build it from scratch alongside a craftsman, practise, and dye a scarf of their own, according to the interview.
The change reaches the trade itself. "My father's generation was a generation with no technical exchange at all," Nakamura says. He has started dyeing together in his own workshop with a 35-year-old dyer from Toshima Ward, each showing the other his own techniques and what the younger man inherited from his father. On the future of kimono he says: "If we want to carry it forward another hundred, two hundred years, I believe it has to explode again."
Nakamura's account is here for what it shows about a Tokyo dye house. For a wider view of the crafts a Tokyo visitor can meet, from tea ceremony and washi to bonsai and tatami, our overview is the place to start.
For a traveller, Japanese indigo dye is not a plant to grow or a recipe to follow. It is a chain: a leaf, a year from seed to dye, a vat whose cloth turns blue in the air and the rinse, and the aishi who still make the dye themselves. The label on a bolt of blue cloth names the first link and hides the rest.
Three questions are enough to read what is in front of you. How was this dye made, in a fermented vat or by a chemical route? How deep is the colour, and how many times was the cloth dipped to get it? And who made it, and where does the person who made it work now? The answers will not always be on the tag, and that is the reason to ask.
Cover image: Piece (indigo-dyed cotton), Japan. The Metropolitan Museum of Art, 1982.385.6, Gift of Amanda Stinchecum, 1982 (Open Access, CC0 1.0)