Aggie...the 1st time you used indigo it wasn't going to "cling" like it does after several times of using it. This is probably why you got better results after the 1st time. Henna works on the same principal really. Now, I have little "wash out" of color on either henna or indigo, but this is after using these herbs several times each. The more you use them, the more they uptake. People should know this when they use these herbs...the color and how much "cling" you get increases w/ each use as far as I have been using them (1 year+) and I've seen this w/ people who've been using them far longer.
If my hair were short and thin,
I can't see that would matter given how the product works. It would probably work better because it would be easier to get it to the scalp. Fortunately the one who applies it to me knows what they're doing!
My hair has grown since I started and even using them as frugally as I do (w/ my liquids/dye release time) I've now had to add more powder to give me full coverage. LOL...I add as I need and now I need.