A Brief History of Indigo Dye

Indigo is a historically significant dye that has been used for at least 5,000 years, and probably longer, by many cultures around the world. Manuscripts and tombs records contain examples of indigo. Indigo-dyed cloth has been found at archeological sites in Peru dating back 6,000 years, and with Egyptian mummies going back 5,000 years. Indigo was used in Guatemala, China, Japan and Africa. India domesticated indigo and has served as a significant indigo dye center. Indigo was an important commodity on the Silk Road, and traded as far away as Europe.

Historical indigo dye collection - photo by Shisha-Tom
Technical University of Dresden, Germany

In the 1700s, the Linnaeus Apostles collected information about indigo during their travels around the world, and Northern and Southern American plantations grew indigo for trade to the detriment of their enslaved workers. In the late 1800s, Levis Strauss famously produced sturdy work pants for miners from canvas sails and indigo dye; and German chemist Johann von Baeyer developed a synthetic indigo dye that has almost replaced natural indigo dye.

Indigo plant from which indigo is produced - photo by Saimon2000bd

Several plant species produce indigo dye. Indigofera tinctoria is called "true indigo", but other species such as I. arrecta and I. suffruticosa also produce indigo dye. The leaves contain the dye, which is invisible and attached to a glucose molecule. The leaves are gathered and soaked in water, where they go through a fermentation process. Soaking the leaves causes the glucose to split off. After soaking, you can remove the leaves because the indigo is in the water. You can dye directly in the vat, or drain the water and dry the extracted dye into cakes.

Indigo plant extract sample - photo by Bray Dunes

In its natural state, indigo is insoluble in water, and must go through this process where it is ‘reduced’ and put into a liquid state with the oxygen removed. In the ‘reduced’ state the indigo dye is a water soluble liquid and is a yellow green color. In this form the indigo is able to penetrate the fibers of the fabric. When the fabric is removed from the dye vat it is initially this same yellow green color, but begins to turn blue as the oxygen in the air reacts with the indigo. As the indigo oxidizes it becomes trapped within the fibers, making the dye permanent. 

Indigo dye examples - photo for Jacquard Indigo Tie Dye Kit
(Dharma Trading Co.)

Even though synthetic dye is widely used today, there is an ongoing effort to help farmers and dyers retain the knowledge and practice of growing and harvesting indigo, extracting the dye through fermentation, and using the dye to produce beautiful artisan and industrial-scale fabrics.

Learn More:

• Indigo Dye Kit Instruction Manual, by Jacquard Products. See the History section.
• Indigo: A World of Blue, documentary by Maiwa Productions.
• Indigo Workshop, by Michel Garcia. Natural Dye Workshop II, by Studio Galli.
• Indigo Dye, see the History section. Wikipedia.
• Indigo and Blue: A Marriage Made in Heaven, by Jenny Balfour-Paul. Textile Museum Journal 47 (January 2020): pages 160–85.
• Indigo: Egyptian Mummies to Blue Jeans, by Jenny Balfour-Paul. London: British Museum Press, 2016.
• Oldest Known Indigo Dye Found in Peru, podcast by Cynthia Graber. Scientific American, September 14, 2016.
• People Have Been Dyeing Fabric Indigo Blue for 6,000 Years, by Steph Yin. The New York Times, September 16, 2016.
• Textilia Linnaeana: Global 18th Century Textile Traditions & Trade, by Viveka Hansen, fifth volume in the Mundus Linnae Series, issued by the IK Foundation & Company (London 2017). Multiple references to indigo.