This plant is native of the tropics and in occurrence Vietnam. Historically, Indigo was used as a natural way of dyeing clothes fabrics in blue but in modern days it is a synthetic form of indigo that is used. Around 20 million kilos of synthetic indigo is produced every year just to color jeans in blue.
A SOON TO BE LOST TRADITION
The North of Vietnam around Sapa, the Hmong people still use the natural indigo plant to extract the blue compound. The indigo plants are harvested on neat plots of land on the hillsides, always scattered near the Hmong’s homes. One yield crops twice a year and the plants generally reach 60 cm high. The dye is contained in the leaves which are then extracted once the leaves have been fermented and then oxidize it will produce a blue powder.
A given fabric is then mixed in with the dye for around half an hour then hung up to oxidize into a distinctive blue color. The more a fabric is mixed with the dye and worked on, the darker it will be. The black of the Hmong fabrics is achieved by repeating this method, twice a day for a month.