Well ok so it's not actually a dye in the typical sense of the word. It's more a coating of color that acts as a dye to transform the color of your hair as well as condition it.
Unlike chemical hair dyes that lost the hairs scales up and deposits color into the hair (damaging those lovely locks on the way), henna is a natural plant based powder that has been used for thousands of years. Think back to ancient Egypt and Cleopatra! In fact there are records of henna being used up to 9000 years ago.
Step 1: Get Ready, Get Set, DYE!
Powdered henna is mixed with water, or other liquids (I have used coffee in the past) until it is the consistency of a thick sauce. Too thick of a mix and it will not spread over the hair easily, too thin and it will run all over making a huge mess.
I add lavender oil to the henna I mix for my hair. Although henna does not have the strong ammonia smell as chemical hair dyes, the smell reminds me of a wet dog. Plus depending on the oils you add, it can also be a great treatment for the hair and scalp.
Step 2: Mis En Place
1) your bowl of mixed henna
2) a comb for separating your hair
3) a small towel to clean up any henna that gets away from you
4) a plastic shower cap or similar
5) towel to wrap your head once the henna is on
You may also want some clips to hold the hair as you divide it. Just be sure the clips, comb and all other utensils are plastic or wood.
Step 3: Applying the Henna
If any of the henna gets on your skin, wipe it off as quickly as possible. You can see by the staining on my glove that the color begins to sink in pretty quick and it will stain (remember Mehndi). Aren't you glad you are wearing gloves.
Vaseline can be put in a thin layer around the hairline to prevent staining the face. I personally don't like using Vaseline on my skin so I try to keep it off or wipe it clean instead.
Step 4: Get Ready to Wait
You can also use a small towel heated in the microwave in 30 second intervals and wrapped over the head. Just be sure to check the towel every 30 seconds to make certain it doesn't burn, catch fire or get so hot as to burn your skin when it is wrapped onto the head.
Now comes the waiting, and yes if is more waiting than those boxes hair dyes. It might even take as long as a professional color job at a salon. At a minimum the henna needs to set for 90 minutes, but a couple of hours is really better. While you are waiting you might want to find something to do and make the time pass faster. Read a book, clean house (I generally use some of the wait time to clean up any utensils and the area I was when applying the henna. There is always a spot or two that the henna has gotten off to no matter how careful I try to be)
Maybe spend the time creating an instructable to share with the world!
I have even put the henna on before bed and slept with a towel to keep the pillow clean. If the henna paste dries ot will not hurt your hair or skin and washes out just as well the next morning, it might give leave an interesting pattern on your pillow if your hair isn't covered well. Just NEVER try sleeping with chemical hair dyes or you might wake up bald!
Step 5: Of Course There Has to Be a Disclaimer
This risk is multiplied of the product you are using on your hair has added chemicals. But even with pure henna there are some people who can have a reaction to the product. If you feel any burning, itching or discomfort while applying henna or during the treatment, wash your hair with water and consult a medical professional.
For me the positives far outweigh the negatives for using henna, but there are some negatives:
Not as easy to go buy at the local store as chemical hair colors
Takes several hours to complete the color process
Rinsing can use a LOT of water. During the summer I can submerge my head repeatedly in a filled tub to rinse, however winter usually means using the faucet and that uses more water.
The positives to overcome these minor obstacles:
It's way cheaper to use than other hair dyes or a salon.
It can be ordered cheaply online with quick delivery
The time waiting can be spent doing a lot of other things that I have probably put off doing.
The water used to rinse my hair isn't going back into the ground with a ton of unpronounceable chemicals that might end up being there for another several millennia.
Hope you were able to get some good info from this instructable, and please leave a comment if you wish. I would love to hear what you think!