* Oxidation: The active ingredients in hair bleach, typically hydrogen peroxide and an alkalizing agent like ammonia, work together to oxidize the melanin in your hair. Melanin is the pigment that gives your hair its natural color.
* Opening the Cuticle: The alkalizing agent in bleach raises the hair's cuticle (the outermost layer), allowing the hydrogen peroxide to penetrate the hair shaft.
* Melanin Breakdown: Once inside the hair shaft, the hydrogen peroxide breaks down the melanin molecules. The more melanin that is broken down, the lighter the hair becomes.
* Damage to Hair Structure: Bleach can weaken the hair's protein structure (keratin). This can lead to dryness, brittleness, breakage, and split ends. The extent of the damage depends on the strength of the bleach, the length of time it's left on the hair, and the overall health of the hair.
* Potential for Chemical Burns: If bleach is left on the scalp for too long or is too strong, it can cause chemical burns to the scalp.
In summary, hair bleach lightens hair by oxidizing the melanin pigment, but it can also damage the hair's structure and potentially burn the scalp if used improperly.