The cause of hair damage can be:
Such effects include staining, discoloration, and a permanent change in shape. The products used to carry out these procedures are able to penetrate the cuticular layer into the cortex. Chemical perm compositions destroy disulfide bonds in polypeptide units.
Solar radiation, salt, chlorinated water - these factors can lead to the rupture of stable chemical bonds in the hair. Solar radiation can not only discolor hair but also dry it out, which increases the susceptibility of hair damage.
Using a curling iron, hairdryer, or other irons which do not pass through hair without a trace. Heating destroys the temporary (hydrogen) bonds in the hair, connecting the polypeptide links - this allows you to give your hair a new shape. However, excessive heat leads to irreparable damage to the hair structure.