2. The raw materials

This picture shows the five basic materials required for extracting the Indigo. The two bottles contain sake (rice wine) and from the left, the four piles contain sukumo (the fermented leaves), fusuma (wheat bran), hardwood ash and lime. Why do they use such things for dyeing? Even sake is used for dyeing? Let's look at these things one by one, and see how they are used.


Sukumo is the name given to fermented leaves of Polygonum Tinctorium. Aizome is a very complicated long process and the chemical compound 'Indican' contained in the raw leaves must be converted into 'Indigo' by composting the leaves.

Since the plants grown in the southern part of Japan are richer in 'Indican', all the main sukumo producers are in Tokushima. Kosoen gets this precious ingredient from one of those providers. (The painstaking sukumo making process will be introduced soon.)

Sukumo is packed in straw bags for shipping. It is very expensive and if Mr. Murata and his workers fail in maintaining control of a batch of indigo, they would lose around 300,000 yen (around $2700), and this doesn't include labour costs!


Fusuma (wheat bran)

Fusuma needs to be cooked before used.

Both sake and fusuma provide food for bacteria during the fermentation process.

Wood Ash

Ash is used to control the alkalinity in a form of 'Aku' (ash-lye). Mr. Murata, the owner of Kosoen, explains that it is getting harder and harder to obtain good ash as well as other materials.

He specially orders ash made purely from hard woods such as Japanese-oak or camellia. According to the wood and the way the ash is preserved, even though only for a few days, the condition of the ash can change dramatically.


Lime is added three times directly to the vat to control the alkalinity during a session. The timing and quantity added are critical.

The dye liquid should be maintained at a pH of around 11, but Mr. Murata says that he threw away very expensive pH measurement machines! After years of trial and error he has finally learned to rely only on his own senses- his eyes, nose, tongue and all the rest of his body!

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