Keratin: what it does and does not do for hair
A hair strand is over 90% keratin. Here is why that is not enough to repair damaged hair, and what actually helps.
Keratin is the protein a hair strand is built from. That is where the confusion starts: if hair is keratin, then applying keratin ought to rebuild it. In reality things are a little simpler and a little less spectacular.
What actually happens
A hair strand is dead tissue. It does not heal the way skin heals. A product with hydrolysed keratin does not rebuild the strand; it temporarily fills the damaged parts of the cuticle, the outer layer. The result shows immediately: smoother hair, less static, easier combing.
Why the effect does not last forever
Because it is a deposited layer, not a repair. It washes away gradually. That is why keratin treatments are repeated, and why a conditioner or mask used consistently matters more than a single intensive treatment.
What does prevent damage
Lower heat when drying, a microfibre towel instead of rubbing, a wide-tooth comb on wet hair, and trimming the ends regularly. None of it is spectacular, but it stops damage before it happens, which no product can do afterwards.