Dying White Hair with Henna and Indigo

Dear reader,

I am 31 years old and I am trying to dye my white hair with a combination of henna and indigo.

I have no problem with henna, it dyes the white hair a bright orange and leaves my black hair just the way it is.

It’s the indigo I have trouble with. I’ve watched just about every video there is on youtube and read quite a bit about the plant and its varieties but I end up with orange hair 99% of the time although sometimes the strands of hair a bit more red, meaning the indigo did work to some extent but the rest of the white hair remains this bright orange color.

Unfortunately, the scientific information about indigo dying for hair is very scarce.

You’ll find plenty of information about dying clothes with indigo with various processes but no very little information about using indigo do dye hair.

From what I understand, all I need to do is to add (warm) water to powdered indigo and wait for about 15 minutes and apply on my hair and wait for 20 minutes. The problem is that all the information I can find is so vague and doesn’t sound reliable. Here’s the following questions I have:

1. What’s warm? I’d like to know at what exact temperature indigo will release the most dye.

2. Why can’t you directly put the indigo mixture on your hair and have the dye release happening then. Isn’t this the objective? That the dye goes in to the hair? I don’t understand the process of having the dye released. If the dye is released but it’s not apply to the hair, how can it dye the hair? In other words, once the powder has released the dye, how can it still dye the hair?

3. What happens if you leave the indigo for longer than 20 minutes? It is like chemical hair dye where your hair will just get darker and darker? From what I’ve read, the indigo will stop releasing dye after 20 minutes in your hair so that there’s no point in leaving it any longer. Here’s what’s weird though: the gloves I used with indigo one had some indigo mixture leftover no it. I left it there and it dyed the plastic a very deep blue. If it wasn’t that way after 20 minutes, how did it become such an intense color afterwards? I understand there’s a reaction with oxygen which take place but why is it that the same doesn’t reaction doesn’t happen to my hair?

4. How can I tell which kind of indigo I’m using? From what I’ve read, there are quite a lot of varieties, which one is the most effective in dying your hair?:
Genus Indigofera: Most natural indigo.
Indigofera Tinctoria: found in Asia.
Strobilanthes cusia: found in Japan, in colder climate.
Indigofera suffruticosa: found in South America
Indigofera arrecta: found in Central or South America

5. I’ve also read that indigo is not soluble in water on Wikipedia. If it’s not soluble in water, why add water to it for dye release?