A
blowdryer or
hair dryer is an
electromechanical device designed to blow normal or hot
air over damp
hair, in order to
accelerate the
evaporation of water particles and dry the hair. Blowdryers allow better control over the shape and style of hair, by accelerating and controlling the formation of temporary
hydrogen bonds inside each strand. These hydrogen bonds are very powerful (allowing for stronger hair shaping than even the sulfur bonds formed by
permanent waving products), but are temporary and extremely vulnerable to
humidity. They disappear with a single washing of the hair.