I figured you guys might question why I think that oils or conditioner stops the henna from conditioning as much as possible. Everything I have read said that it inhibits color but the following charts suggest that the color and conditioning effects both happen when the henna bonds to the hair.
So it just makes sense to me that if you add something that will block some of the color you will also block out the same amount of potential conditioning.
I plan to only use water from now on but I never had any concerns about the ACV because I do ACV rinses (without rinsing it out) with no problems. The owner of RenaissanceHenna.com has done many expirements on henna and she determined that when you use something acidic to develop the henna the stain is lighter than it is without an acid. I want as much color as possible to show on my dark hair so I am going to stop using ACV.
Here is what that website says:
About the lemon juice .....I started out thinking that acid was a must for henna dye release. Henna is acidic and so what some henna experts said about lemon juice or other acidic stuff being used to “trigger” dye release seemed to make sense, despite the fact that many people throughout the Asian sub-continent and elsewhere were managing just fine to get dye release from henna into their hair with just plain water (cold, warm,and hot) and they’d never heard of such absurdity as adding lemon juice and the like. Since setting up this website, I’ve carried out my own trials, largely inspired by Henna Cat, and spurred on by others at hennatribe.com who have also conducted their own trials or been using henna and plain water for years and been openly sour to the lemon juice acid theory.
My conclusion is that henna does not need acidic liquid of any kind added to it to trigger dye release ! Plain water works just fine, and in fact my trials show that plain water works better and stains better than lemon juice ! You can add something acidic such as lemon juice, lime juice, orange juice (* do not squeeze or handle oranges yourself if you are allergic to PPD as the dye in orange peel is high in PPD ), or organic cidar vinegar if you want to lighten the henna colour, but for a henna rich, deep, colour you need only water. My own trials have shown that the addition of acidic liquid lightens the colour and you’ll notice the difference in colour just from a comparison of pastes mixed with plain water and mixed with water/acid - have a look at these photos :
henna paste mixed with plain hot water
henna paste mixed with hot water and cider vinegar
I plan to only use water from now on but I never had any concerns about the ACV because I do ACV rinses (without rinsing it out) with no problems. The owner of RenaissanceHenna.com has done many expirements on henna and she determined that when you use something acidic to develop the henna the stain is lighter than it is without an acid. I want as much color as possible to show on my dark hair so I am going to stop using ACV.
Here is what that website says:
About the lemon juice .....I started out thinking that acid was a must for henna dye release. Henna is acidic and so what some henna experts said about lemon juice or other acidic stuff being used to “trigger” dye release seemed to make sense, despite the fact that many people throughout the Asian sub-continent and elsewhere were managing just fine to get dye release from henna into their hair with just plain water (cold, warm,and hot) and they’d never heard of such absurdity as adding lemon juice and the like. Since setting up this website, I’ve carried out my own trials, largely inspired by Henna Cat, and spurred on by others at hennatribe.com who have also conducted their own trials or been using henna and plain water for years and been openly sour to the lemon juice acid theory.
My conclusion is that henna does not need acidic liquid of any kind added to it to trigger dye release ! Plain water works just fine, and in fact my trials show that plain water works better and stains better than lemon juice ! You can add something acidic such as lemon juice, lime juice, orange juice (* do not squeeze or handle oranges yourself if you are allergic to PPD as the dye in orange peel is high in PPD ), or organic cidar vinegar if you want to lighten the henna colour, but for a henna rich, deep, colour you need only water. My own trials have shown that the addition of acidic liquid lightens the colour and you’ll notice the difference in colour just from a comparison of pastes mixed with plain water and mixed with water/acid - have a look at these photos :
henna paste mixed with plain hot water
henna paste mixed with hot water and cider vinegar
Most old time henna heads 'round here have figured this out a while ago. 
.
I did a 2-step - henna gloss then indigo. I sat under my steamer with the henna gloss for 30 minutes and then rinsed. My grays were covered nicely and then I applied the indigo for 2 hours. Rinsed and viola! No more letting my henna sit on my head for hours.
No fuss, no muss in much less time. I used to spend the whole day with my treatments and now I know I can do all the applications in 3-4 hours. Nice.
