<P> A hair dryer, hairdryer or blow dryer is an electromechanical device that blows ambient or hot air over damp hair to speed the evaporation of water to dry the hair . Blow dryers enable better control over the shape and style of hair, by accelerating and controlling the formation of temporary hydrogen bonds within each strand . These bonds are powerful (allowing stronger hair shaping than 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 . </P> <P> Hairstyles using blow dryers usually have volume and discipline, which can be further improved with styling products and hairbrushes during drying to add tension, hold and lift . </P> <P> Blow dryers were invented in the late 19th century . The first model was created by Alexander F. "Beau" Godefroy in his salon in France in 1890 . The handheld, household hair dryer first appeared in 1920 . Blow dryers are used in beauty salons by professional stylists and in the household by consumers . </P> <P> Most hair dryers consist of electric heating coils and a fan (usually powered by a universal motor). The heating element in most dryers is a bare, coiled nichrome wire that is wrapped around mica insulators . Nichrome is used because of two important properties: It is a poor conductor of electricity and it does not oxidize when heated . </P>

When did hand held hair dryers come out