Hair coloring dates back at least to the ancient Romans, and many societies have used herbal solutions to dye their hair. Modern hair coloring began in 1909 when a French chemist came up with the first commercial hair color.

What is color?
Color is a complex subject, but put simply, its the way light reflects from pigments. Change either the pigment or the kind of light, and you change the color we see. There are two main kinds of color: red-yellow (warm shades) and red-blue (cool shades).

How do I know what sort of coloring I have?
1. If you have:
A skin tone of ivory, peach, creamy beige, light or dark golden brown, or coppery colored, and
Your eyes are blue, blue-green, hazel, light green, amber or coffee colored
then you have warm coloring and should choose a warm shade for your hair (gold with red highlights, gold or honey brown, copper or mahogany).
2. If you have:
A skin tone of rosy pink or beige, dark olive, dark brown or ebony and
Your eyes are light or dark blue, deep green, brown or black
then you have cool coloring and should choose a cool shade for your hair (burgundy highlights, ash or platinum blonde, brown, dark brown, black, gray, or white).

What is hair?
Hair consists of a shaft, which we see, and its root, which is below the skin in a follicle (little pit). The shaft is dead. The living part is the follicle and the few cells just emerging from it at the base of the shaft. This is how the hair grows, by cells at its base subdividing, pushing upwards, hardening and developing pigment. Typically, each of our hairs grows at about inch per month and lives anywhere from 3 to 5 years.

Hair is made of keratin, the same protein thats in our fingernails and skin, plus some other proteins, and a pigment called melanin. There are two kinds of melanin: eumelanin (shades from brown to black) and phaeomelanin (yellowish-blond, ginger and red colors).

What are the ingredients of permanent hair color?
There are two main ones, ammonia and hydrogen peroxide. Ammonia opens the cuticle of the hair shaft so the color molecules can enter. Hydrogen peroxide bleaches the hair so that new color can be added to create the desired shade. Some permanent colors come with more natural ingredients than others, but will likely still have some synthetic chemicals as well.

How is hair color changed?
The hair shaft is like a tube. The outside is the cuticle and inside is the cortex with the pigment. Any applied coloring goes through the cuticle to the cortex, but it may or may not interact with your natural pigment.

If you have dark hair and want it lighter, there are 2 steps: (1) your color is bleached and (2) the new color is added

If you have light-colored hair and want it darker, only step (2) is needed.

Hair coloring is thought of in 3 levels, based on how long the coloring lasts.
Level 1, semi-permanent hair color - The color molecules are very tiny. They go through the hairs cuticle into the cortex where your natural color is, but they dont interact with your natural pigment. Because theyre so tiny, they leave the hair more easily and so this coloring level isnt permanent. It lasts through about 6 to 12 shampoos. It also doesnt lighten your hair because theres no peroxide or ammonia present. Nor does it cover gray more than about 50%.
Level 2, demi-permanent hair color - The color molecules are again very small and they go through into the cortex. Here, they combine with each other to form bigger molecules. Therefore they dont wash out as quickly, lasting through a couple dozen shampoos. This type of coloring includes some peroxide, which enables it to subtly lighten the natural shade and blend better with existing gray.
Level 3, permanent hair color - Again, tiny molecules enter the cortex but this time they react to the natural molecules and expand to a size too large to be washed out. Ammonia and peroxide are both used, so the hair is first lightened, and then colored to the desired shade. Since the final shade is a combination of your natural color and the added color, it will be unique to you.

Hair coloring has become so popular because its so easy to customize, said Jacquelyn, the office manager at Salon Cabochon in Sacramento, CA. And so many more men have discovered the fun of changing your hair color once in a while. I mean, why just pay attention to the cut and style? Why not be creative with the color too?