i joined here wanting this tone. it's taken me about 4 applications (month) 6/8 hours each to leave in to get this now which won't colour wise take in anymore, which i happy with now. at first i did debate on adding indigo but i actually liked the red so i'm staying with it.
i believe there are some variations and ideas you should consider -
.water type (do you need acidity in your mix)
(i personally only need just warm chamomile tea in my mixture)
.hair type and colour (darker it is naturally the darker the outcome if you use purely henna otherwise add cassia)
.virgin/damaged hair- damaged hair like i had soaks up quicker than virgin.
.henna gloss ? works well to get the henna colours slowly
.it's very permanent
.conditioning benefits
.henna type, some are more orange and some come out darker.


naturally dark brown but starting picture was blonde and black streaks. eek
middle pic was adding process of the henna
last two pics are the colour i have now- very close to your colour your after.
yemeni henna use here.