Hair Dye and Hair Bleach: How Do They Work?

I recently bleached the tips of my hair, then dyed it red. It got me wondering how the hair dying process really worked. I noticed the moment I bleached my hair started becoming dry and split ends seemed to be popping up all over the place, so I will be talking about the causes of this too.

Hair bleach contains ammonia and peroxide. Ammonia is a colorless, pungent, suffocating, high-water-soluble, gaseous compound ( usually used in fertilizers and disinfectants. Peroxide, also known as hydrogen peroxide, is a liquid that is simply used as a bleaching agent. ( The ammonia works as a catalyst that activates the peroxide (bleaching agent). Once the bleach is applied to the hair, the bleach oxidizes with the melanin molecules found in hair causing it to become lighter. Hair melanin is what determines our hair color, hence if you have a lot of melanin, your hair is dark, if you have little melanin, your hair color is light. 

Hair dye works similarly to bleach, just not as strong. It also contains ammonia and hydrogen peroxide. The dye breaks into the open cuticles of one's hair. The reaction opens and expands hair molecules to the point that they cannot be washed out, hence making it permanent. There are temporary dyes as well which is less harmful to hair.

I can conclude from my research that my hair has been drying out because of the harsh chemicals in the dye and bleach. The reactions formed during the hair dying process also destroyed the nutrients and healthy oils in my hair, hence the split ends. Any chemicals put into hair has the potential to destroy it. After reading about this, would you want to dye your hair? 



I dyed the tips of my hair red when I was in high school. I have blonde hair and the dye stayed in FOREVER. When I was reading your blog I was wondering why dye seems to stay longer in light colored hair than it does in dark colored hair. You state that light hair has low melanin and that the dye oxidizes with the melanin molecules in the hair. If there are fewer melanin molecules in my hair, wouldn't this mean that the hair dye would come out quicker? I am probably just confusing myself though!

My friend has dirty blonde hair and she dyed the back of it red but she didn't need bleach for the color to show and her color stayed for a while. I guess it depends on how blonde your hair is for the color to stay, which is why if you have darker hair then you'd have to bleach it for the color to stay permanent/ show. I think since your hair is already blonde the color stays longer cause you didn't have to bleach it. With darker hair, the bleach damages the hair and that could cause breakage which may be the reason why the color doesn't last as long.

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