by Mags Kavanaugh-AskMags
There are two kinds of melanin found in the hair: eumelanin (the most common and responsible for hair shades from brown to black) and phaeomelanin (responsible for yellowish-blond, ginger, and red colors).
The absence of pigment produces white/gray hair.
All human hair types at childhood contain the two types of melanin, Eumelanin, and Pheomelanin. There is no hair type with only one type of melanin. Dark hair has a higher percentage (99%) of the brown pigment, eumelanin, and a much lower percentage (about 1%) of pheomelanin. Blonde hair still has about 95% of eumelanin and about 5% of pheomelanin. Of course, dark hair has a much higher overall amount of melanin (eumelanin and pheomelanin) than blond hair.
Let us look at some numerical examples without putting much emphasis on the numbers because they are strictly hypothetical: If we assume that a dark hair strand has 10,000 “molecules” of total melanin, then by the ratios above, 9900 “molecules” (99%) of these would be eumelanin and 100 “molecules” (1%) would be pheomelanin. In comparison, a blond hair strand of equal size may have only 100 “molecules” of total melanin.
Of these, 95 “molecules” are eumelanin (95%) and 5 “molecules” are pheomelanin (5%). When both dark and blond hair types are bleached, most of the accessible eumelanin in the two types of hair would be broken down and discolored, and only very little of the pheomelanin would do so. The reason why pheomelanin is harder to bleach is that it has sulfur linkages (or ties) that make the molecule more tightly packed and inaccessible to the bleach. The end result is that dark hair lifts to a brassy undertone because of the significant amount of pheomelanin left behind (let’s say 90 molecules), while blonde hair reaches the palest yellow stage because only very few pheomelanin were there to start with, and they get even less after the bleach (Let’s say 3 or 4 molecules).
So the lesson to keep in mind is that all types of hair have both types of melanin, but the concentrations differ.
What are the ingredients in peroxide-
(also known as the developer or oxidizing agent) — This ingredient, in varying forms and strengths, helps initiate the color-forming process and creates longer-lasting color.
The larger the volume of the developer, the greater the amount of sulfur is removed from the hair. Loss of sulfur causes hair to harden and lose weight. This is why, for the majority of hair coloring, the developer is maintained at 30% volume or less for less damage to the hair.
Level 1, semi-permanent color — This product adds color without changing natural color dramatically. The hair color contains tiny color molecules that enter the hair’s cuticle, or outer layer, and go into your hair’s cortex. They don’t interact with your natural pigments. And since the molecules are small, they eventually exit the hair shaft after several shampoos, leaving the hair as it was before treatment. This level generally lasts for 6 to 12 shampoos, covers up to 50 percent gray, enhances your natural color, and leaves no roots. This hair coloring won’t lighten your hair color because it contains no ammonia or peroxide.
The outer layer of the hair shaft, its cuticle, must be opened before permanent color can be deposited into the hair. Once the cuticle is open, the dye reacts with the inner portion of the hair, the cortex, to deposit or remove the color. Most permanent hair colors use a two-step process (usually occurring simultaneously) which first removes the original color of the hair and then deposits a new color. It’s essentially the same process as lightening, except a colorant is then bonded within the hair shaft.
Bleach is used to lighten the hair. The bleach reacts with the melanin in hair, removing the color in an irreversible chemical reaction. The bleach oxidizes the melanin molecule. The melanin is still present, but the oxidized molecule is colorless. However, bleached hair tends to have a pale yellow tint. The yellow color is the natural color of keratin, the structural protein in hair.
Also, bleach reacts more readily with the dark eumelanin pigment than with the phaeomelanin, so some gold or red residual color may remain after lightening. Hydrogen peroxide is one of the most common lightening agents. The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin.
Suffice to know that for a chemical reaction to take place, the products of a chemical reaction must achieve a lower energy level (or are more at ease) than the starting reactants which are (tense or edgy). It is like trying to push a rock downhill but before you are able to get it to the edge of the hill (where it can roll down on its own), it has to climb a small mound of dirt. In doing so you have to give it a push and spend some energy.
In hair color, the push over the small mound of dirt that your rock has to overcome (or the energy to get your primary intermediate activated) is provided by the oxidizer removing hydrogen atoms from the primary intermediate and making it chemically active (grouchy ready to bite). Keep in mind, however, that some of the most useful interactions between hydrogen and oxygen are not covalent but rather weaker interactions known as hydrogen bonds which give water its fluid nature and vital role in life.
These cysteine derivatives form cross-links or bridges among themselves which cause pheomelanin to be more tightly packed and resistant to bleach. The switch in the cell to synthesize either type of melanin (by adding tyrosine or adding cysteine) is related to genetic factors.
Both types of melanins grow to form large granules of melanin chains wrapped around protein molecules. The chemical structure of both types is quite complex, and both have what is referred to as a highly conjugated double bond structure which results in the dark color of the pigment and allows the molecule to absorb UV light and offer protection against harmful radiation.
When melanin is oxidized, the conjugated double-bond structure starts to break up and the melanin gradually loses color and becomes “bleached”. It is not eliminated from the hair but remains in the hair in its colorless “bleached” form.
It is a very small molecule, which evaporates rapidly (hence the strong odor) and rinses out quickly from the hair. Hair coloring products labeled as “Ammonia-Free” utilize other chemical agents to provide alkalinity, and it is important to remember that “ammonia-free” does not mean “alkalinity-free”.