Henna & Amla

I want to make sure that my hair doesn't get straighter over time when I henna, and I have seen it mentioned a few times that if you mix in some Amla powder, it will keep your hair curly. I was wondering if anyone has any experience with this, and what sort of ratio of amla to henna should I be using in my mix? Thanks

You could give it a try, but I don't think it's a 100% guaranteed thing. People that use amla in order to counteract straightening tend to mix equal amounts of henna and amla together.

With the first treatment, the straightening effect of henna will be fairly minimal anyway, it tends to happen after several treatments.
I believe the reason it happens is because the effect of henna coating the hair shaft weighs the hair strand down and therefore stretches the curl. So the more often you henna, the more pronounced the effect will be because your hair will have progressive coats. Not everyone experiences but I have certainly noticed it in my hair. I am not sure what amla does to counteract this effect. I would have thought that it would coat the strand even more.