How do you make green jeans? Besides using organic cotton, you need lots of indigofera tinctoria, the tropical plant that yields natural indigo dye. Natural indigo dyeing techniques are friendlier to the earth and the people handling the dye. Indigo is tricky because it's not water soluble. Natural indigo dyeing is a 4,000-year-old process that elegantly gets around this little hurdle using an ancient fermentation process that doesn't require fixing agents, potentially harmful azo, formaldehyde or hydrosulphite. The natural fermented dye also ends up consuming less water than modern, synthetic techniques, and when finished it is biodegradable.

The indigo mixture is kept in a deep terra cotta pot sunken into the ground, tended vigilantly and mixed every day by skilled artisans. While this is a more expensive production method, the return in indigo quality and saturation richness, not to mention you end up with an earth friendly pair of jeans, makes the process and price worth it.

Eco-Tobi brands using natural indigo dyeing:
Gilded Age
Good Society
Nudie

Here's a vid of the daily handling of the fermentation process by natural indigo dyeing artisans. (He uses his tongue to check the pH level of the dye, it's non-toxic don't worry!)