Have you ever wondered why you need shampoo to wash your hair? That is because shampoo, particularly its ingredient called sulfate, breaks the surface tension of the water so that it can stick your hair. Surface tension is what makes the raindrops round as they fall from the sky. Dewdrops are formed because of surface tension, too. Water striders and boatmen alike use surface tension so that they can float on water.
On a smaller scale, surface tension – with the help of grease and dirt that accumulated – prevents water from sticking to your hair. If your hair does not have the right degree of wetness, water cannot penetrate as deep as possible for you to wash the dirt and the oil from it. So chemists invented shampoo and put sulfate into it. In most cases, sulfates create a rich lather that makes you think that your shampoo is very efficient in cleaning your hair. However, the goodness of rich lather goes as far only in commercials. That is because sulfate can irritate skin.