To understand the concept of hair porosity, it helps to know a bit about the structure of your hair, which consists of three layers. These layers include:
- The cuticle: This is the tough, protective outer layer of your hair that’s made up of smaller cuticles that overlap each other, similar to shingles on a roof.
- The cortex: This is the thickest layer of your hair. It contains fibrous proteins and the pigment that gives your hair its color.
- The medulla: This is the soft, central part of the hair shaft.
For your hair to stay healthy and hydrated, water, oils, and other moisturizing products need to be able to pass through the cuticle to get to the cortex.
But, if the cuticles are too close together, it’s not easy for water and oils to penetrate the hair. This can make it harder for your hair to get the moisture it needs.
Also, if the cuticles are too widely spaced, your hair will have a harder time retaining moisture and staying hydrated.
How your hair absorbs and retains moisture is largely due to genetics. So, if low porosity hair runs in your family, there’s a good chance you’ll have low porosity hair, too. But while genetics can affect porosity, it isn’t the only contributing factor.
Blow drying, bleaching, straightening, overwashing, and using harsh products can all damage your hair over time. This can cause your hair cuticles to become raised and open, which may make it harder for your hair to retain moisture.
In addition to hair treatments, too much ultraviolet exposure can also increase the porosity of your hair. To protect your hair from the sun, wear a hat or some type of head covering when you’re outdoors.