Almost every commercial I see on television for hair products boasts it's hydrating abilities in some way. Usually accompanied by random splashes of water, a woman with long wet hair whipping it about or the obligatory waterfall. Usually rather than wanting to buy the product I long for a tropical vacation or a glass of water.
Dehydrated hair is a common concern among, well, everyone. No one wants dry, limp or frizzy hair. We all want to be like the woman in the commercials with long luminous locks.
Prevention is always key, pretty much with everything in life. Dehydrated hair can be caused by pollution (smoke, chemicals etc), products (harsh shampoos/conditioners), and chemical treatments (coloring). Anything that strips the hair of the outer protective layer will result in dry weak hair.
What to do?
Offer client's hydrating hair treatments, hair oils, making sure they only use quality shampoo/conditioners and styling products that will not strip their hair.