Features of Japanese indigo

About indigo dyring

It was introduced from China in ancient times and became popular as a color for common people in the Edo period. With its strong sterilizing effect, dyed clothes prevented skin diseases and poisonous insects. There are various varieties of indigo, such as “Kojoko”(小上粉), “Hyakkan”(百貫), and “Senbon”(千本). MAITO mainly uses “Sukumo,” which is made by fermenting “Kojoko” indigo produced in Tokushima, which has been highly regarded as the best since the Edo period.

Pigment of indigo dye

The indigo plant contains a substance called indican. When the plant cells are destroyed, an enzyme in the leaves causes the indican to oxidize easily. The oxidized material that comes into contact with the air becomes indigo pigment, which gives the plant its indigo color. Indigo dye is a pigment that is insoluble in water.
The process of making this water-insoluble indigo pigment soluble in an alkaline solution using a redox reaction is called “Aidate”(making indigo requid).
The process of indigo production by the action of microorganisms is called “Hakkoudate”(Reduction by fermentation) and the process using chemicals is called “Kagakudate” (chemical indigo reduction).
When the alkaline solution is adsorbed by the fiber and oxidized again in the fiber, the indigo pigment develops an indigo color.

About “Sukumo”

Sukumo is made by fermenting dried indigo leaves with water. The harvested indigo is dried and crushed by hand with rubbing. At this time, the stems and debris are removed, leaving only the leaves. The crushed leaves and water are mixed well and allowed to ferment. The mixture is allowed to mature for about one month and then dried in the shade. To the resulting scum, lye and lime are mixed to adjust the pH to an alkaline level, and wheat bran called bran, sake, glucose, etc., which nourish the microorganisms, are added to produce indigo dye solution.

Growing Japanese indigo

Seeds that have overwintered twice have a significantly lower germination rate, so they must be planted every year.
The timing of seed planting depends on the location, but it is a long-established custom to sow seeds on the day of Taian in March.
>>How to grow Japanese indigo

Making precipitated indigo

As the name suggests, precipitated indigo is made by precipitating the indigo pigment.
First, the harvested indigo is placed in a bucket with a lid and water is added to cover it. It is left to ferment for about two days (depending on the temperature).
When the leaves turn brown and a thin film forms on the surface, fermentation is complete.During this process, indican and enzymes dissolve in the water.The liquid is removed from the bucket, lime is added, and the pH is adjusted to an alkaline level.It is then stirred until blue bubbles appear.This stirring causes oxidation, and indigo is produced. After stirring, the insoluble indigo pigment precipitates in about two days.The supernatant is discarded, and the precipitated muddy indigo pigment is called “Doroai”(mud indigo), and when it is dried, it becomes a pigment called “Ranjou”(indigo tablet).

The method of indigo dyeing

Indigo dye is insoluble in water, but its reduced form can dissolve in an alkaline solution.Once oxidized, the indigo dye is deoxidized and reduced to become a dye suitable for indigo dyeing.Indigo dyeing methods can be divided into two categories: fermentation dyeing, which uses reducing bacteria, and chemical dyeing, which uses reducing agents.

Indigo color name