Indigo refers to a natural dark blue colorant obtained from the tropical Indigofera tinctoria plants. This species of shrub is naturalized to the tropical and temperate areas of Asia and Africa and has been cultivated elsewhere for centuries; its location of origin is uncertain. The use of indigo was first mentioned in Indian manuscripts in the 4th century BCE; it was first exported to Europe in Roman times.

The natural material is collected as a precipitate from a fermented solution of the plant, where the coloring component, indigotin, is extracted as a colorless glycoside that turns blue with oxidation. Indigo is a fine, intense powder which may be used directly as a pigment in oil, tempera, or watercolor media. Since the exposed pigment can fade rapidly in strong sunlight, it is rarely used in art or fine textiles today. The same dye compound is now also produced synthetically.

Drawn from

• Kimberly L. Jones, PhD, Inca: Conquests of the Andes / Los Incas y las conquistas de los Andes, Gallery text, 2015.
• Getty Vocabulary, AAT (indigo (colorant): AAT: 300013055; indigo (color): AAT: 300311066; Indigofera tinctoria (species): AAT: 300311568).
• Ann Rowe, “Glossary,” in Weaving and Dyeing in Highland Ecuador, edited by Ann Rowe, Laura Miller and Lynn Meisch (Austin: University of Texas Press, 2007): 289-295.

• Victoria and Albert Museum (YouTube)
  Watch a video demonstrating the process of indigo dyeing.
• Metropolitan Museum of Art
  Read an essay about Indian textiles, trade, and production.
• Metropolitan Museum of Art
  Read an essay about Asante textile arts.
• Metropolitan Museum of Art
  Read an essay about the materials and techniques of American quilts and coverlets.