You interfere in your hair’s biochemistry.
As I have written earlier (hair extension aftercare), hair consists of 3 layers. The first main part is the cuticle (scaled overlapping layer) which consists of many layers of tissues without a nucleus.
Unfortunately, chemical hair treatments reduce the number of tissues and leave our hair dull and lifeless.
Producers put different compounds in their hair dyes to make hair look shiny.
In European hair there are no pigments in the cuticula, but they are very important when it
comes to reflecting light.
The second main part is the cortex (fibrous layer) which contains pigments. Pigments are produced by melanocytes. They have got round shape and lots of dendrites. This dye-producing-tissue transmits and injects pigments into its surroundings. It spreads in the hair by diffusion. When it is diffused in the cortex, it looks from the outside as if you were watching water-colour behind a glass supposing the horny layer is healthy.
If the horny layer is not healthy, hair will be dull and lifeless and the isoelectric points won’t
meet. The inner and outer charge will differ.
The outer would show a negative plus.
This is the reason why you have to dye the tip/end of your hair with a different oxidative
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