Mechanical friction is caused by using a brush or a cmb (even if they are good ones) Salt in our hair after swimming in the sea, rubbing our head on a pillow while sleeping, using rubberbands.. all of these cause damage or loss to our hair. Such damage has particularly to do with wet hair because then it is more susceptible to stretching and breaking.
Use wide-toothed comb to remove tangles and do not comb wet hair continuously. Also, avoid hair dryer to dry your hair.
Happy Summer ladies!