Indigo - overview



		1.	Overview



		2.	History of use



		3.	Making the pigment



		4.	Technical details

Brief description of Indigo:

Blue pigment prepared from plants until the end of 19th century. Since 1870 it has been manufactured synthetically. It has fair tinting strength and may fade rapidly when exposed to strong sunlight. Worked in tempera or beneath varnish it can be very stable.

Names for Indigo:



Pronounciation:

in • deh • go

Word origin:

The name "Indigo" comes from Greek indicon = from India.

Non-English names:

German

French

Italian

Indigo;
plant: Färberwaid

indigo;
plant: guède, pastel

indaco;
plant: guado

Chemical name:

2,2'-Biindolinyliden-3,3'-dion

A painted swatch of Indigo:

Source of Indigo:

The most typical source of indigo is woad, shown in this field. Today, indigo is also produced by the bacterium E. coli through genetic engineering:

Indigo is most commonly used as a dye for fabrics, as this woman is doing (Podor, Senegal). To make painting pigments, the dye is "fixed" to a ground white material, in a processed called "laking."
The four panels below depict the traditional process of indigo manufacture in India. Clockwise starting at top left, beating by machinery; "rahut," or Persian wheel; straining the indigo; press and boiling house.

Plants: woad (Isatis tinctoria L.), Indigofera tinctoria L. and others