I'd like to share my experience with natural indigo dyeing.
Based on the Shibori technics, I dyed different types of organic cotton and linen fabrics.
First I had to prepare the dyeing bath, using natural indigo pigments. I learnt the process from "La Maison de l'Indigo" at Marie Galante in Guadeloupe. It is a fully natural dye bath. Michel Garcia is also using a similar process.
So I reduced the indigo powder into a hot tap water + alcohol 90° solution. Then I mixed this solution A to the dyeing bath prepared with fructose, quicklime and water heated at 50°C during 1h. It is called a "1, 2, 3" vat!