Healthy hair is usually strong and elastic due to greasing produced by sebaceous glands. It can be stretched 1.5 times longer and then it returns to its normal length undamaged. It is almost as strong as aluminum and is capable to sustain the weight of 0.1 to 0.2 kg. That’s why in old times people used ropes made of women’s plaits to elevate heavy loads.
Hair is hygroscopic, i.e. it can absorb water. It is rather acidproof, but vulnerable to alkali.
Hair has the ability to accumulate certain substances. That’s why it’s successfully used by criminalists in their investigations.
First hair appears on the head of a child when he is in a womb of a mother, approximately on 4-5 month of pregnancy.
Intensity of hair growth depends on the season and time of day: it grows faster in spring and summer than in winter and autumn. Also hair growth is not that intensive at night than during daytime.
A single hair can grow from 2 to 7 years with the speed of 0,3-0,4 mm a day.
Hair grows averagely 2 years on men’s heads and 4-5 years on women’s.
Normally a man loses 30-100 hair a day.
Each follicle bears about 20-30 hair during human life.
Hair grows about 1 cm a month.
An adult man has about 100,000 hair, and its amount depends on color. A single hair of Africans and Asians is the thickest. It can be 3 times thicker than that of European blondes. But at the same time blondes have the biggest amount of hair on their heads – about 150,000. Redheads have the thickest hair, but its amount is smaller than that of brunettes.