Indigo - Añil, Some traces of the blue pigment were found in pre-Hispanic remains. There is evidence that it has been used in Mexico and Central America since ancient times. Upon the arrival of the Spanish, the production and export of this highly valued colourant in Europe increased considerably.
Along with India, the New World countries were the main producers of indigo, which at the same time undermined the production of "Pastel Blue", a pigment created in the south of France.
In the 19th century, the natural indigo molecule was identified. Its chemical substitute allowed industrialists to manufacture a low-cost and more profitable blue dye while leaving out natural indigo.
In the natural indigo producing countries, production is now very low. It is a rare, valuable and expensive product because it is highly dependent on weather conditions. The plant is harvested once a year and the manufacturing process is long and very precise.
Fabrication process: The "indigo blue" dye is found as a fermented paste. To obtain this dye, a manufacturing process known since pre-Hispanic times must be followed.
1. The leaves and tender branches of the Indigofera shrub, also known locally as the Xiquilite (or Xiuhquílitl, “blue grass” in Nahuatl), are harvested after the rains in September and October.
2. Both elements are crushed, deposited in a container and kept at the bottom with stones. The container is filled with water and left that way for at least 12 hours. Then the juice dissolves in the water.
3. Then the mixture is shaken and aerated for several days so that oxygen can enter. This causes a fermentation that allows the blue dye to be soluble; it is called Indigotine. The mixture is allowed to stand so that the blue sediment settles at the bottom of the container.
4. Then the colourant mixed with the water is filtered and dried in the sun to obtain a paste that can be used for dyeing. Manufacturing can take up to ten days.
Indigotine, which is insoluble, can be extracted directly from the used water. To dye, you have to mix with a reducer so that it is soluble and therefore will penetrate the fibres. In contact with the air, a new oxidation occurs that gives the pigment its final colour, restores its insoluble character and becomes very resistant to washing. Today, in Mexico, indigo is still cultivated and produced in some regions and communities of Michoacán (Huacana), Puebla (Hueyapan), Chiapas and Oaxaca (Santiago Niltepec). It is these towns that allow the artisans of Oaxaca to weave their blue wool threads.
