Natural indigo is one of the oldest dye. Indigo has been known to man for more than 4000 years. In ancient Egypt and ancient India, indigo was used for dyeing. Also in Asia we have an evidence of using indigo. A Chinese old book in about third century B.C. says "Blue from indigo plant is deeper than its origin." The literal translation of this proverb "blue from indigo plant is deeper than its origin", actually means "one attains a greater mastery than his teacher". This corresponds to the English proverb "The new rose becomes more beautiful than the old rose".
The word "indigo" originally means a dye from India. Now a day indigo also
means the colorant in natural indigo. Indigo can be obtained from a variety of plants such as Indigofera, Storobilanthes and Polygonum.
In Japan Polygonum
is used to make natural indigo. Oldest evidence of indigo dyeing in Japan is
appeared in 10th century. In 18th century, every class of the people
wear indigo products.
Grown leaves in summer are cut
to make natural indigo dye
Polygonum had been cultivated all over Japan. Yield was highest in Shikoku
area. Climate of this region called Tokushima (ancient name, Awa) is good
for the plant. The river called the Yoshino supplies much water and good soil. About 200 years ago,
this region, Awa, was very wealthy as a production center of natural indigo. Spring is the planting
season and in summer Polygonum grows to be cut. Leaves are separated from stems by wind.
Leaves collected are subjected to fermentation.
Soil like dye which contains indigo colorant is made after this fermentation. Fermentation must be
accomplished under wet and
warm conditions. Every three days the farmer must mix and add water.
After the mixing, the plant was covered with a straw mat (of a rice plant). The
farmers think the production of indigo is to bring up a baby, they call
the straw mat bedclothes and they call this room a bed-room. If the leaves
are not moist enough, temperature does not raise and the fermentation
does not proceeds well. In such a case, they say the dye caught a cold.
Again and again they mix. By the fermentation for 3 months, they can get
soil like product which contains 3 to 5 % of indigo. The farmers pack
and send them to dyers.
Indigo cannot be used for dyeing directly because it is not soluble to water.
Dyeing is quite different
are fermented for 3 months. Water is added every 3-4 days and
the leaves are mixed.