HomeThe science of cosmeticsHow do hair products work?How does hair work?

We have it everywhere. On average we each have nearly 100,000 hairs, and that's just on our heads! During our most primitive years, the original aim of these fantastic filaments was to both protect us from the cold and cool us down in extreme heat. In a more modern society, they are used primarily for cosmetic and decorative purposes, at times expressing who we are and even what we stand for! Hair is brilliant, but how does it work? 

What is hair made from? 

A single human hair is made up of hundreds of intertwining protein fibres called keratin. Keratin is also found in your fingernails, but in sheets rather than the fibre form in your hair.  

Hair grows by rapid division of cells at its base (the root) in the follicle. As the cells keep dividing and forming, the older cells are pushed up from the follicle's base. They then stretch, harden and show their colour from pigment which is found in the hair's central cortex. Hair's pigment is melanin, which is also found in our skin. Once the hair stem cells reach the top of the bulb, they change shape and there is an increase in keratin production. The parts of the cell which aren't made from keratin are gradually broken down and the fully formed hair fibre is released. However, the hair is still relatively soft until it is 15mm above the surface of the skin. 

What makes hair different on different people? 

The outer part of the hair shaft is called the cuticle and consists of flattened scales of keratin. In normal hair the scales are more raised when wet and closed when dry, giving a smooth surface. If the hair is damaged, the scales may be permanently open, making the hair weak and porous (able to absorb water). Porous hair can feel dry, rough and look frizzy.  

The cuticle scales are translucent, meaning that they allow light to pass through, but if the hair is damaged, the scales are raised with means light is scatted off their surface in different directions. If light is scattered rather than reflected evenly from both within the hair and its surface, hair will look dull and lacklustre. This means that light passes through the hair's inner core, the cortex. 

Inside the cuticle is the cortex, which contains the coloured melanin pigments that give the hair its colour. Different types of melanin give the hair its unique colour.  

In the centre of the hair shaft there is also often a fibrous honeycomb structure called the medulla. 

Why is hair so important today? 

In today's society, it's important to feel good about ourselves. Losing hair for one reason or another can lead to uncertainty and lack of confidence in people, so it's always important to support each other. Mental health and wellbeing are so important to a healthy lifestyle and what we do with whatever hair we have can influence that.  

Hair can be used to make ourselves feel good by changing it, whether that's changing the colour or styling it a certain way. Facial hair is also key to this, offering men a way to personalise their face to take male grooming seriously. 

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