Indigo (Indigofera tinctoria)
There is no single plant called “indigo.” Rather, “indigo” can be obtained from a number of different and unrelated plant species which all contain indigotin dye. These include Isatis tinctoria (“woad”) common in Central Asia and Europe, Persicaria tinctoria common in East Asia, and Lonchocarpus cyanescens common in West Africa.
This natural indigo dye powder comes from the Indigofera tinctoria (also called “true indigo”) plant, sourced from India.
It is important to note that natural, organic indigo (i.e. from an indigo plant) is not toxic. In fact indigo is considered medicinal and appears in teas and sweets in China and Japan. However, the process of reducing indigo (removing oxygen from the vat in preparation for dyeing) is often performed with harsh chemicals which create a toxic environment. In addition, some indigo dyers use synthetic, rather than natural, indigo.
You can learn more about mixing a natural indigo vat and other natural dye techniques from our DVD, Natural Dye Workshop with Michel Garcia: Colors of Provence Using Sustainable Methods.