Given the position in which it is found, the cuticle is the first to be exposed to sensitising and damaging factors, such as: physical factors light, chlorine, pollution mechanical factors (frequent washes with aggressive cleansers, rubbing, brushing, regular use of hair dryer or hot iron chemical factors colour-treatments, bleachings and perms repeated with excessive frequency These factors cause a progressive alteration in the external tissue, with the subsequent weakening of the entire hair structure.