The beautiful, deep rich color of indigo blue has come to be called "Japanese blue".
Ai (藍), as it's known in Japanese, is made from the leaves of the Japanese indigo plant and was initially used by aristrocrats and samurai.It can now be found adding color to everything from kimonos to clothing like blue jeans and linens. Sadly, most of the indigo color we see now is made synthetically.
A Dyeing Tradition
The traditional way of making indigo dye or aizome (藍染め) can take a year to produce.
First the leaves are harvested and dried in the sun while being flipped repeatedly by a broom. Next they are fermented to create sukumo, a concentrated version of the dye. This is mixed with lye and lime before being fermented again. The depth of colour will depend on the length of time the sukumo is left to ferment.
Currently only 4-5 producers, all located in Tokushima Prefecture in Shikoku, make sukumo the traditional way. It's known as “Awa-ai” and is famous for its distinct, premium color.
Indigo is so beloved in Japan, that the Japanese have a multitude of names for the all the shades of blue produced: from the lightest, almost white shade known as aijiro (藍白) to the darkest, deepest shade called noukon (濃紺).