Indigo dyes are an organic compound with a unique blue color. Indigo is a natural dye extracted from leaves of some plants indigofera genus or indigofera tinctoria. Indigofera plant was grown massively in Asia and also some part of other subcontinent. India is the origin of indigofera and gradually it spread out over the world.. A couple centuries ago this indigo dye was super exclusive and only royalty people was able to afford it. In that time it was similar to tea, coffee, silk or even gold. Indigo plant was first discovered around 1600 B.C. The first synthetic indigo dyes was developed in 1880’s by German chemist Adlof Von Bayer and it’s marketed in 1900’s. Indigo dyes classified as Vat dyes which is insoluble in water and no affinity to fibre.Indigo dyes has poor color fastness which let the color of denim fabric to change naturally. Indigo is the primary color of blue jeans. Indigo is exclusively used to produce attractive blue shades on denim along with desired wash down property. Indigo dyes are classified as 2 different chemical forms.:
- Natural Form (Insoluble in Water)
- Leuco Form (Soluble in Water)
Use of Indigo Dyes:
Primarily indigo dyes is used to dye cotton yarn, mainly used to denim clothes for blue jeans. Smaller amount of Indigo dyes are used to dye wool & silk.
Indigo is a type of Vat dye. To get the dyestuff onto the yarn or fabric, it is solubilized in water with help of a reducing agent. It works best on natural fibres like cotton, wool, silk. There are lots of ingredients and recipe to use for Indigo dyeing. First of all, need to put yarn or fabric in the dyeing Vat then it gets in contact with atmospheric oxygen and this process blinds the color molecules to the fibre of the yarn. The reason denim fades in the modern dyeing process. When oxygen hits the yarn or fabric then it magically transforms the color from yellow green to blue.