Rainbow Research Henna Hair Color and Conditioner - Medium Brown leaves hair a chestnut color. It coats each hair shaft with color. It smooths and seals the hair's cuticle for greater shine and texturizes hair to give it body. Henna Hair Color blends naturally, fades gradually and lasts 4 to 6 weeks. Henna is a natural, colorless, conditioner for all hair types and colors.