Myrobalan, Terminalia chebula, is a dye powder from the finely ground nuts of the myrobalan tree. It is a tannin and a flavonoid that gives light yellow colors or olive greens if you do an afterbath of iron.
Myrobalan is an excellent source of tannins and nearly all cotton textiles in India are treated with myrobalan before being mordanted. The pale yellow dye is very wash and lightfast and gives delicate greens if overdyed with indigo. Even though Myrobalan is a tannin, the Art and Science of Natural Dyeing book says it is considered a mordant dye that should be used with a mordant. That didn’t make sense to me since it is an excellent source of tannins…..but, I’m not a scientist or chemist, so I can’t dispute it!
Use 20-30% weight of fiber when used as a dye and 10-20% when used as a tannin prior to mordanting cellulose materials.