A recent article by Keith Recker describes the process of fermented indigo dyeing Fofana has perfected at his farm in the district of Siby, Mali in conjunction with the local community, where two types of indigenous West African indigo are grown.

With leaves harvested from his indigo farm near Bamako, Fofana starts the temperamental process of turning greenery into blue dye. Macerating in the vat, the leaves release indican, a colorless amino acid. Bacteria-driven fermentation transforms this into indigotin—the dye responsible for both nineteenth-century jeans and some of the twenty-first century’s most beautiful artisan textiles.

https://www.instagram.com/p/BaYbAqzFVn4/ This method of dyeing yields a stunning range of blue shades, achieved by repeated dipping of the material into the 'live' vats of fermented indigo.

In Bamanan, a language spoken in Mali, there are twelve words for blue, starting with bagafu, the palest blue, a barely-there color achieved with a single dip. Lomassa, divine blue, is the darkest tone. Saharan Tuaregs treasure lomassa head wraps, whose depth is sometimes enhanced by beating additional pigment into the fibers with a wooden mallet. The indigo, which rubs off onto their skin, serves as a sunscreen—and gives them their nickname, the Blue Men of the Desert.