In addition to a number of other functions, the skin is mainly intended to protect human beings against physical or chemical external aggression as well as internal organic losses.

It lls this “barrier” part through a complex structure whose external part is made up of the stratum corneum, a horny layer covered with a hydrolipidic protective lm. This function is only ensured when this horny layer made up of the accumulation of dead cells is properly moisturized, as the water is the keratin plasticizer.