As you can see there are few different level of black hair color. Im aiming for the number 21 the most solid Pitch darkest black. And this type of black is attainable without chemical infused dye. Dark Blue black is achievable by repeated application of Indigo alone on previously hennad, or by completing a 2 step henna and indigo back to back 3 times to ajdust for a black hair that won't budge.
So I applied indigo to my previously hennad hair (bye bye reddish hair). Sectioning is key, it will make the hair dye go much smoother and quicker in time with assurance every sectioned hair will be covered.
The Light mountain in black is small percentage of henna with larger portion of indigofera tintoria, I used this for my bottom half, it dyed the red pretty well. Repeated application with this should build to pitch black hair overtime, more easily on already fully hennad hair.
Sea salt is supposed to be added for gray resistant hair so indigo can adhere better, I don't have gray hair yet, but i figured this tactic won't be a bad idea, since i do want stubborn black hair. I left the indigo on my hair 11 hours to deepen my hair color the most i can. This was my first indigo experience, i have 3 more whole head indigo to go to adjust to that coolest jet blue black hair color. So far im liking the outcome.