Blue is the world’s favourite colour. You could cite any number of reasons for this: the sky and ocean are blue; it evokes a sense of peace and tranquility; it is often associated with positive qualities; most importantly, everyone, and I mean everyone, looks good in blue. As such, Japan’s enduring love for indigo is in good global company. So beloved is this colour that there are 48 officially-named hues of indigo, not to mention Japanese denim in that inimitable shade of dark indigo dubbed ‘Japan Blue’. It may be a coincidence that the word for indigo, ‘ai,’ is a homophone for ‘love; in the same language — but only maybe.
A history of indigo dyeing in Japan
Aizome — literally ‘indigo dyeing’ — is the technique that uses the fermented leaves of Polygonum tinctorium, variously known as ‘Japanese indigo,’ ‘Chinese indigo,’ and ‘dyer’s knotweed.’ A number of species of indigo-bearing plants grow in tropical, subtropical, and temperate climates around the world — such as woad and indigofera — and it is likely that various cultures independently developed dyeing techniques at different times throughout history using the leaves local to their area.
In the case of Japan, scholars think this subtropical variant (Persicaria tinctoria) was introduced to Japan from southern China shortly after 500 AD, perhaps by way of Korean artisans and Buddhist monks. The existence of thousands of beautifully-preserved woven textiles from the Nara period (646-794) onwards indicates that even then, there was a sophisticated appreciation of the intricate and subtle shades of colours, including all the hues of indigo. The use of indigo spread far and wide across the country over the subsequent centuries.
During the ninth century, dark blues were reserved for certain ranks among the nobility. By the twelfth century, the use of blues had spread to the samurai warrior class. A particular shade of blue known as ‘kachi-iro’ was popular with them for battle attire, since it was a homonym for victory . During the Edo period (1603-1868), it became common for both rural commoners and urban dwellers to dress themselves in shades of indigo, particularly as it was one of the few colours that were permitted under sumptuary laws that banned the wearing of bright colours by commoners. So ubiquitous was indigo that woodblock prints featuring the heavy use of blue (Prussian or Berlin blue) were known as ‘aizome-e’ or ‘aizuri-e,’ ‘blue-printed pictures.’
It was around the same time that Tokushima Prefecture (the former Awa Province) also became a commercial centre for indigo production, not long after cotton was introduced to Japan in the mid-15th century. Indigo-dyeing strengthened soft cotton fibres by building up in layers, prolonging the lifespan of the garment and improving its texture with long-term wearing. This ‘aji’ or ‘flavour’ that comes with age is still highly valued today.
Indigo production peaked at the start of the 20th century with around 40,000 acres under active cultivation; this fell as cheaper synthetic imports flooded the market. Today, there are around 50 acres, mostly cultivated with government support. Tokushima continues to lead Japan in indigo production.
From plant to dye
Indigo is harvested in the summer, so cultivation for the year begins in winter. It is typically planted in beds in late winter, and then transplanted into fields in spring. Once the plants have grown to around 50–60cm in height, the leaves are ready to be harvested. This is done twice (and in some cases, thrice) in summer.
To make sukumo (indigo dye) the traditional way, the leaves are first shredded and separated from their stems, and then thoroughly sun-dried. The dried leaves are stored in bags. In early September, on a suitably auspicious day in the Buddhist calendar, the dried leaves are heaped in nedoko (lit. sleeping bed). After mixing the leaves with sufficient water to create a moist kind of compost, they are piled up to around one metre high and left to ferment — each pile contains around four to six tonnes of leaves.
Every five days, the fermenting leaves must be raked through, turned, and re-formed into the same pile, all the while making sure there is adequate moisture and warmth. This is a several-person job. As the temperature falls, the leaves must be covered to maintain a high-enough temperature for fermentation. Around late October, the producers take care to loosen up any leaf clumps to ensure even fermentation.
The resulting material is called sukumo. This cannot be used as-is for dyeing, and must first rest for several months before being combined with natural wood ash and water to create a highly alkaline environment that makes the pigments water-soluble. Some indigo artisans may add ingredients like sake, rice or wheat bran, honey, or lime to speed up the process. When a piece of fabric is dipped in the dye and exposed to air, the indigo pigments will react with oxygen in the air and change colour. Repeated submersions will result in deeper, darker shades of indigo. The blues are fixed when the fabric is thoroughly washed in water.
Japanese aizome techniques
Japanese artisans have developed dozens of dyeing techniques to create all kinds of patterns and effects on fabric. These are some of the most common.
Shibori
Shibori derives from the verb ‘to wring’ or ‘to squeeze,’ and describes the manner in which designs are created on fabric through knotting, folding, tying, gathering, pleating, and pinching, and then tying the cloth tightly with string to leave undyed white patches. The patterns become visible when the bindings are removed.
Danzome
Like the indigo version of ombré hair dyeing, this technique results in gradations of indigo. Here, a piece of fabric is dyed in stages.
Where to experience aizome indigo dyeing in Japan
Tokyo and the surrounding areas
Kosoen, Ome City
A family-run studio offering natural indigo dyeing experiences. There’s an adjacent shop selling clothing and accessories designed by the Murata brothers, who own Kosoen. Reservations required at least 3 days in advance.
Wanariya, Taito Ward
A family-friendly workshop and shop — kids as young as 4 can join. They sell garments, hats, bags, and scarves, but also offer dyeing experiences using products sold at their store. You can dye handkerchiefs, tenugui (hand towels), tote bags, caps, T-shirts, stoles, and long-sleeved shirts. Reservations required.
Japan Open-Air Folk House Museum, Kawasaki City
A workshop that also holds exhibitions and lectures. Entry here is included in the admission fee for the Open-Air Museum, though the experience itself is paid and requires advance reservations.
Kyoto
Kobo Ainoyakata
A charming indigo dyeing studio in rural Ohara run by sought-after artisan Toru Shimomura. Features all-natural lye pigment fermentation and hand-dyeing. Wabunka offers a private experience. Advance reservation required.
Honaizome Miyabiori Kobo
Details to be confirmed.
Yamamoto Roketsu Dyeing Studio
Experience a more unusual take on indigo-dyeing at this studio. Roketsu is a wax-resist dyeing technique practiced in Kyoto; it’s a little similar to batik. Advance reservation required.
Tokushima (Shikoku)
Watanabe’s
One of the rare operations that grows the indigo, makes the dye, and manufactures the products to be dyed. Visitors can see the fields or fermenting huts before dyeing their own fabric. Advance reservation required.
Aizumicho Historical Museum (Ai no Yakata)
A short and straightforward dyeing experience at a small indigo-themed museum. Three time slots for the workshop are available every day, but advance reservations by phone are required.
Yamauchi, Mima City, Tokushima Prefecture
A dyeing experience that includes either an indigo farm visit or watching sukumo-making, which makes it quite time-efficient. Advance reservations required.
Elsewhere in Japan
Aizome Kasuri Kobo, Fukuoka
Operated by fourth and fifth-generation dyers Takeshi and Kensuke Yamamura, this workshop specialises in Kurume Kasuri, indigo-dyed hand-woven cotton. Background here.
Sources and further reading
Balfour-Paul, Jenny. Indigo: Egyptian Mummies to Blue Jeans. United Kingdom: British Museum Press, 2011.
Promotion Council for “Ai no Furusato Awa.” Awa - The Home of “Ai”: Searching for the Supreme Blue of Japanese indigo, trans. Mana Sato. Tokushima, 2020.