Hair dryer

A hair dryer, hairdryer or blow dryer is an electromechanical device designed to blow normal or hot air over damp hair to accelerate the evaporation of water particles and dry the hair. Blow dryers 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 powerful (allowing for 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.

Hairstyles using blow dryers usually have volume and discipline, which can be further improved by the use of styling products and hairbrushes during drying to add tension, hold and lift.

Blow dryers were invented around the end of the 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.

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 wire is used in heating elements because of two important properties: It is a poor conductor of electricity and it does not oxidize when heated.

In modern models, a survey of stores in 2007 showed that most hair dryers have ceramic heating elements (like ceramic heaters)—because of their “instant heat” capability. This means that it takes less time for the dryers to heat up, so it takes a lot less time for the hair to dry.

Many of these dryers have “normal mode” buttons that turn off the heater and blow room-temperature air while the button is pressed. This function helps to maintain the hairstyle by setting it. The colder air reduces frizz and can help to bolster shine in the hair.

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Wikipedia