Thank you for your totally awesome detail!
I'm a huge fan of henna but if the treatment isn't done properly you can run into an assortment of problems. I've been using henna for six months and here are some of the issues I ran into, why and how I solved them.
1st problem: Dry brittle hair and very little color
Why- I used an "off" brand of henna. Rainbow henna from Whole Foods.
Two other brands that suck in my opinion.
Reshma Henna-decent color but super itchy scalp
Jamila " Superior quality"- Little color and weak condition
Solution- I swear by Jamila "punjabi prime" from Mehindi.com and or Dulhan with a recent date and batch no.
2nd problem: Loss of curl. I experienced this after my first 4 treatments. Mainly in the front of my head where I naturally have a looser curl pattern anyway.
Why: I was doing the treatments too often. I started off henna-ing ONCE a week and the tention I was putting on the front of my head did not make the situation any better.
Solution- I now only Henna once a month with a gloss in between. To help my bring back my lost curl I started to mix Hesh Pharma Amla in with the henna. So my current mixture is 50 grams of henna, 50 grams of amla. My curls are conditioned and consistent all over.
3rd problem- Split ends, Single strand knots, breakage.
These, many naturals experience before they Henna. Poor treatments can make it worse.
Why- Bad choice of acid. I used to use ACV, Orange Juice, coffee. Dry, Dry, Dry and more Dry. They're way too acidic and though I got these recommendations from Indian women you have to remember the sebum from their scalp gets onto their strands effortlessly. Not so with curlies and kinkys.
Solution- keep it mild. I prefer green tea, Amla, or a teaspoon of red wine. I am also extremely generous with oils in my henna. I add plenty of olive oil, Flax seed oil (adds strength and flexiblilty to your curls) and coconut oil is easily absorbed.
4th problem- Hairloss. I've never experienced this infact I'm noticing very little hair in my brush after detangling. Why- Those that have, can probably attribute this to not conditioning properly after a treatment. I notice some mention of Giovanni products. Which as a 3c I find that they just don't condition deep enough. The ingredients always list tons of water, alcohols, proteins and barely any oils.
Solution-I suggest that atleast when you henna to keep your conditioners heavy and rich. Become a mixologist. Mix coconut oil, coconut milk, olive oil, shea butter or oil in with all natural conditioners and always apply heat. I use a dryer or I put on a plastic cap and sit in the sun for atleast 15 minutes. My favorite conditioners are Deity America Deep Penetrating Conditioner for Damaged Hair (CVS, Beauty Supply Stores usually carry it) Aubrey Organics Honeysuckle Rose and blend of coconut milk, avocodo oil, and Burt's Bees more moisture conditioner.
-Moisture is everything with or with out henna. DT once a week.
-Stay clear of cones, parabens, glycols and alcohols. I own Aussie Moist and Herbal Essences Hello Hydration even some Deva Curl products. But I use them sparingly for long lasting styles between Hennas. They're not to be applied everyday. They will dry out your hair.
- Henna is not a quick fix. You don't actually "see" results from henna until the forth treatment and if you were coloring your hair with drugstore haircolors or salon haircolors before, expect the results to take even longer to show up. But the results are amazing. Handling damage takes time and trims.
I hope my lengthy response was helpful to you.