Indigo has been made from several different dye plants, such as Indigofera tinctoria and Indigo suffraticosa. The plants are cut and soaked in warm water and mixed with oxygen to release the dyestuff. The resulting mixture is then dried to produce chunks of indigo pigment.
To use the Indigo in dyeing it must be mixed with Calcium carbonate and Sulphuric acid. Because Sulphuric acid is very corrosive, I prefer to use a pre-mixed solution called Saxon Blue.
To use Saxon Blue:
- Fill a dyepot with water.
- Add a small amount of Saxon Blue.
(The Saxon Blue solution is quite concentrated.)
- Add the wet fiber or yarn to the dyepot.
- Simmer for 30 minutes or until the water is clear.
- If you wish a darker color, you can remove the fiber and add more Saxon Blue to the dyepot.
You don't need to use a mordant when dyeing with Saxon Blue, unless you will be overdyeing the yarn with other natural dyes.
Saxon Blue gives lighter shades than true Indigo, but is easy to use, and works well when blending with other colors.