Characteristics of Hair

Whatever your hair type, all hair shares certain properties:

Characteristics of Hair

Hair is elastic because of the coiled structure of the keratin, and this elasticity increases when hair is wet. Because of its elasticity, a healthy hair can stretch up to 20 or 30 per cent of its length before it breaks.

Hair swells (gets thicker) if it is soaked in water, as the water enters the air spaces between the fibres of the cortex. A hair in good condition can, in fact, absorb about 30 per cent of its own weight in water.

Hair is porous, and liquids can pass between the outer cuticle scales into the cortex. Porosity increases if the cuticle is damaged or if the cuticle scales are lifted through heat, steam or chemical treatments. Sebum and certain conditioning creams or lacquers can decrease the porosity.

Hair is hygroscopic and absorbs moisture from the air. This explains why the same head of hair can behave very differently in dry and humid conditions. When it is humid, hair absorbs a lot more moisture and tends to become frizzy, whereas it tends to be straight in a dry climate. The normal moisture content of hair is about 10 per cent of its weight, but this can increase to 30 per cent.