There are different ways to categorise hair but some classification systems only scratch the surface when it comes to informing your hair regimen.  An understanding of your hair's thickness, porosity and density can determine how prone to damage your hair is and help you with product selection.

1. Thickness

It is important to distinguish between hair thickness and hair density.  Thickness refers to the width of each hair strand. 

A hair shaft is made up of 3 layers:

Cortex – the biggest bulk of the hair also responsible for its colour

Medulla – the innermost layer

Cuticle – the outermost layer that protects the hair

The structure of hair can vary from person to person and even from strand to strand on the same person.  Thick hair tends to contain all three layers, while thin layer may not contain the medulla. 

Thick hair strands are less prone to breakage but find it harder to absorb water.  Thick hair has a larger medulla, which creates more capacity to store water so make sure you apply plenty of moisture-rich products.

Thin hair absorbs water more easily, but the water can easily escape too.  Thin hair loves products that contain protein which adds support by creating a film around the hair fibre.  Be careful not to overuse protein though, but alternate between protein-free products.  Also pay attention to your hair ends and keep up with regular deep conditioning treatments to prevent breakage.  Fine hair can be weighed down by butters and creams so you may prefer to use milks or products in spray form. 

To find out the thickness of your hair, hold a strand between your fingers.  If you can’t feel it, your hair is thin.  If you can barely feel it, it's medium; and, if you can feel it clearly, you have thick hair.  


2. Density

Density refers to the number of hair strands per unit area of your scalp.  The average person has over 2000 hairs strands per square inch.  The number of hair follicles from which your hair grows is determined largely at birth. Since a newborn baby has a much smaller surface area than an adult, the hair follicles are much closer together. No new follicles grow throughout your lifetime so your hair becomes less dense as the follicles spread out as you grow.

You can determine your hair density by how much of your scalp is on show.  The more scalp, the lower the density. 

Be careful not to confuse low density hair with thin hair.  Hair of low density may appear 'thin' but actually have a medium or thick width. 


3. Porosity

 Porosity measures your hair’s ability to absorb and maintain water.  There is an inverse relationship between porosity and hair thickness.  The Greater the hair width, the lower its porosity.

Knowing the porosity of your hair helps you to determine which moisturising products you should use.  Low porosity hair loves light moisturising sprays as adding too much product can weigh down the hair and sit on its surface.  Hair of high porosity can take a lot of moisture so you can apply layers of moisturising products such as leave-in conditioners. 

To get an idea of how porous your hair is, take a dry strand of hair and place it in a glass of water.  If it take a few minutes for the hair to sink to the bottom, your hair is of medium porosity.  Hair of high porosity will sink to the bottom almost immediately, and hair of low porosity will float at the top.





Photo: Element5 Digital via Unsplash