Indigo a deeply moving colour. It comes from the plant Indigofera tinctoria, a dye is made by soaking the leaves so they ferment. It is a centuries old technique and was one of the products that has been traded along routes from Asia to Europe to Africa and then to the Americas. So all cultures have used this deeply moving dye to create beautiful patterns. It has been considered a magical colour because of the colour changes from a deep green to deep purplish blue after the yarns are taken out of the dye bath and hung to dry, the oxidation cause the chemical reaction thus creating a change. It is not a stable colour, it will fade to a soft blue.
samples of traditional resist dye patterns from England:
One of my favorite uses of indigo dye was in the making of denim cloth, a tough wearing fabric that was made into sturdy agricultural wear in the 1870's by Levi Strauss & Co.