A blue from a plant
Indigo dye, called ai in Japanese, comes from plants, and in Japan the most commonly cited source is Japanese indigo (Persicaria tinctoria, long known as tade-ai). The dye does not exist in the green leaf in a ready-to-use form. It has to be released and converted by processing, which is part of what makes indigo dyeing feel like craft rather than simple coloring.
Indigo is thought to have reached Japan from the continent in ancient times, and the plant was cultivated for centuries afterward. Its use grew steadily, and the region of Awa, in present-day Tokushima, became especially well known for indigo production, according to commonly repeated accounts.
How the dye is made and used
Traditional indigo dyeing is built around fermentation. Dried leaves are composted over a period of months into a material called sukumo. That is then placed in a vat with an alkaline liquid, such as one made from wood ash, along with other ingredients that feed the microbes, and left to ferment into a living dye bath. A skilled dyer watches the vat’s color, smell and froth to judge its condition, and tends it over time, which is why the vat is often described as something to be cared for.
When cloth is lifted from the vat, it is a yellowish green. As it meets the air, it oxidizes and turns blue. Dyers dip repeatedly, airing the cloth between dips, to build deeper shades. Names for the many shades, from a pale blue through to a nearly black navy, are part of the vocabulary of Japanese color.
Chemical synthetic indigo has been widely used since the late nineteenth and twentieth centuries, while craftspeople who work with sukumo emphasize the depth and variability of the natural dye. Both are in use today.
Why indigo suited everyday cloth
Indigo became associated with common people for several reasons. In the Edo period, rules at times limited the colors and fabrics that townspeople and farmers could wear, which nudged many toward cotton and muted colors. Cotton took indigo well, and the dye is commonly said to make cloth hardier. A traditional belief held that indigo-dyed garments discouraged insects and snakes, though this is better understood as folk wisdom than as something proven.
The result was blue clothing across daily life:
- Work jackets, trousers and aprons for farmers, fishers and craftspeople.
- Happi coats and firefighters’ jackets, which carried bold white designs.
- Noren, the short curtains that hang at shop doors.
- Futon covers and wrapping cloth, as well as casual summer robes. The yukata robes of summer, for example, are often blue and white.
Dark indigo was also sometimes worn under armor, and a very deep blue sometimes called kachi-iro, a name that sounds like “victory,” was associated with warriors, according to common accounts.
Patterns made with resist
Much of the beauty of Japanese indigo lies in how patterns are made. The blue is deep, so designs are usually created by blocking the dye from reaching parts of the cloth. Common techniques include:
- Shibori, in which cloth is tied, stitched, folded or clamped before dyeing, producing soft, irregular patterns.
- Katazome, where a paste is applied through a stencil to leave a white design.
- Kasuri, a method of dyeing threads in sections before weaving so that blurred, patterned edges appear in the finished cloth.
- Tsutsugaki, free-hand drawing with paste applied from a tube, often used for large designs on bedding covers and festival banners.
These sit inside a broader range of dye and pattern techniques described in the story of Japanese textiles, and the weaving side belongs to Japanese weaving.
Mending, reuse and folk craft
In poorer regions, cloth was valuable. Worn indigo clothing was patched, reinforced with stitching and passed along. Garments made of many layers of patched cloth, sometimes called boro, and the decorative stitching known as sashiko, became admired in the twentieth century as examples of frugality and beauty. In the mingei movement, ordinary indigo textiles were appreciated precisely because they were made for use, and this way of seeing them continues to shape how they are collected.
Indigo today
Indigo has benefited from renewed interest in handmade goods and natural dyes. Workshops produce scarves, bags, and clothing, and indigo-dyed denim has a place in the Japanese clothing industry. Hand dyeing is labor-intensive, and some small studios and farms have struggled to continue, as with many crafts.
For those learning to dye at home, kits are widely sold, but real fermentation vats and strong alkaline baths involve chemicals that can irritate skin, so it is wise to learn from a qualified teacher.