Ladies over at the Henna for Hair forum say you can apply henna as often as you like. Just be aware that in some
cases, frequent henna users experience curl loosening. This hasn't happened to me so far - I just assess my hair after each henna to be sure. It sure has made my hair thicker though, and I welcome that.
So far I seem to be doing a full henna once a month. I've only done two of those. And a gloss two weeks after my full henna. So, that would be twice a month for me - one full strength, and one gloss.
My hair needs at least
200 grams for a full henna. Completely stretched, my hair is below bra strap - going on waist - in the back (the front is shorter), to give you an idea of how much 200 grams will cover. I mix my henna with honey, so that stretches it a bit.
You should, for a full henna, apply it verrrry thick so that it covers each and every strand. It should be like thick frosting on your head LOL. Your head will feel very heavy and it will stretch your hair out almost straight from the weight of it. I wrap my hair around my head before putting on the cling wrap.
I suggest reading this free e-book before attempting henna - it explains everything - how to mix, how to apply, etc:
For the gloss, after experimenting, I think I could about get 4 good glosses out of a 100 gram box ($8 for Jamilla from Mehandi).
Btw, I highly recommend Mehandi's Personal Stash Jamila henna. And her Cassia (neutral henna) is also very good.
- It's often said around the internet that henna is a protein treatment, but it's not. Catherine over at Mehandi wrote a post about it - and she's doing her Phd on henna, so she knows. She said it's actually a tannin treatment. The confusion, I think, comes from the fact that it binds to the protein in your hair. So it does kind of act like a protein treatment, but it isn't one. I also find it far more effective than any temporary protein treatment I've ever used.