What is indigo dyeing?

February 26, 2025

What is indigo?

The raw materials for indigo dyeing are various plants with the name "ai" in them. Since ancient times, they have been prized as medicinal herbs with many beneficial effects. In Japan, indigo has been used in a variety of ways, not only as a dyeing material, but also as a medicinal herb, such as being applied to the skin.

The history of indigo in Japan

It was introduced from China via the Korean Peninsula during the Nara period (there are various theories).

Among the treasures of Shosoin are numerous indigo-dyed fabrics and threads. Judging from the techniques and designs, it is assumed that they were brought from China, India, or the countries that were then known as Persia. When we think of indigo dyeing, we tend to think of it as a traditional Japanese culture, but it seems that there were many countries that were dyeing indigo before Japan.

The effects and benefits of indigo

Indigo-dyed underwear has long been said to be effective against cold sensitivity and rough skin.

It also has a strong insect repellent effect, and it is said that old cloth from the Edo period was free of insect damage only in the areas dyed with indigo. Many people also seem to have experienced that "indigo-dyed underwear and socks do not smell."

In the first place, dyes extracted from plants were pursued for their effectiveness as medicines for illnesses, even before they were used to dye fabric.

In ancient rituals and ceremonies, the colors themselves were expected to have beneficial effects. Considering that they are still used today, it seems that people have actually experienced their effects. Conversely, most of what are called herbal medicines and natural drugs can also be used as dyes.

Versatility revealed by recent research

A 2009 paper from Tokushima University states that tripranthrin "not only has anti-allergic effects, but also anti-cancer and anti-Helicobacter pylori effects." This makes one wonder if indigo could be a panacea.

It is said that people with atopic dermatitis can reduce their symptoms by wearing clothes dyed with natural indigo or by applying natural indigo extract to their bodies.

If you suffer from skin allergies, wearing clothes dyed with natural indigo or using soap containing natural indigo ingredients may help. At the very least, it is thought to be less irritating to the skin and have the effect of suppressing dermatitis.

It is said that in ancient times, there were not as many patients with allergies as there are today, such as atopic dermatitis. If you only eat, wear, and use products made from natural ingredients, you may have a better reaction.

By the way, I used to suffer from atopic dermatitis, but when I changed my shower head to one with a dechlorinating function, my symptoms improved dramatically. Each person reacts to different allergens, but I think that by eliminating each possible cause one by one, you can find a clue to improving your symptoms.

Auspicious color that brings victory

Speaking of lucky charms, dragonflies were also prized as insects that bring victory. Since samurai were always close to death, they probably sought to alleviate their fear of death by believing in them as good luck charms.

The deep indigo dye color, known as "kachi-iro" or "katsu-iro," is known to have been loved by samurai of the Kamakura period, as the dignified and powerful color was considered to be "an auspicious color for victory in battle."

Originally, it was used to make armor, and indigo-dyed clothing was usually worn under armor, making it essential for camping outdoors or overnight stays. Indigo is called Kachi-iro (indigo color), so warlords of the past used indigo-dyed helmet straps, believing that brown was the color of victory and bringing good luck.

Bushu indigo dyeing, popular in kendo uniforms

"The road was four ri long. On the way there was the town of Hanyu, where the blue-striped market was located."

This is the opening line of "Country Teacher," a masterpiece by the Meiji era literary giant Katai Tayama. The blue stripes, a specialty of Bushu, were a representative local industry in Hanyu, and this dyed blue stripe was known throughout the country as Bushu Indigo.

What is Aoshima?

Aojima is an indigo-dyed cotton fabric that began as a side job for farmers in the Kisai area in the late Edo period (Tenmei era). It is said that 80% of kendo uniforms are made with Bushu indigo.

The production of blue-striped dye is centered in Hanyu, Kazo, and Gyoda in the northern Saitama region, and it has been used for work clothes as well as the outer material of tabi socks. During the Meiji period, there were said to be more than 100 indigo dyeing shops in Hanyu alone.

summary

Indigo has deodorizing, insect repellent, and medicinal properties. Recent research has shown that it also has anti-cancer and anti-Helicobacter pylori properties, so it can be said to be truly versatile.

I would like to spread the word about the beauty of indigo to people other than those involved in kendo.

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