I was born and brouht up in India and we had henna shrubs in our garden. We would pick henna leaves, wash it and then blend it in blender with some water. The resulting henna paste ( like green chutney) was then applied to hair. Henna can stain the nails and hands as well. The results are permanent hair colour.
Now I dont have access to henna shrubs in Canada. I use powdered henna and is definately not as powerfull.
Hennna is good but very messy. But I would still not touch artificial dyes.
I hope inversion turns the hair to original color from inside out...