Blondes seriously have more fun. That’s what I usually tell everybody. I’m 26 and started bleaching my hair when I was 12. Even though I have gone dark a few times, I always end up with bleached blonde hair. I’m just happier with blonde hair. I feel like it brightens up my face.
However, bleach can take its toll on your hair very quickly. Bleach penetrates into the hair cortex and removes all the color pigment. The first component of hair lightener / bleach is an alkaline, which lifts up the “scales” of the hair cuticle to allow the next part. An oxidizing agent, like hydrogen peroxide, is added to penetrate deep in the hair shaft to the area where color molecules chill. Then, the bleach starts to lighten the pigment molecules by releasing oxygen molecules during the oxidation process. These oxygen molecules break up the chemical bonds of chromophores, the parts of molecules responsible for color. “The changed chromophore molecules either reflect no color or a color outside the visible spectrum. This absence of color is seen by our eyes as white.”(Wonderopolis: How Does Bleach Work?)
Hair lightening goes through a series of phases. Remember the three primary colors that make every other color are blue, red and yellow. Bleach first removes the blue molecules, which leaves the hair red. This process is very quick, so if you blink, you’ll miss it. Next, the red molecules start to be removed. This process takes a long time, and if you rinse the bleach out during this process, you will be left with orange hair. The last thing it does is removes some of the yellow pigments, which leaves it pale yellow. The natural color of keratin, which is the protein that hair is composed of, is yellow, so your hair will never not be a form of yellow. If you want an actual shade of blonde, you will have to use a toner, but that is a whole other article in itself.
Bleach doesn’t just strip the color molecules in your hair; it strips the protein, vitamins and moisture. It also changes the structure and texture of your hair. Remember how I said that it uses an alkaline solution to raise the cuticle? Well if you over-process your hair, the cuticle will not lay back down, which leaves the hair dull and susceptible to more damage. The cuticle’s purpose is to act as a barrier to protect what’s on the inside of the hair, and if that is damaged, the inside will get damaged too.