Hair porosity be defined as normal, high, or low. It basically means, if the hair can either hold or repel moisture.
If your hair repels water like ducks feathers do, then you have low porosity hair. This type of hair can be harder to style because any styling products used will be resisted with this hair type. By using products such as a deep conditioner in low porosity hair, it will feel stiff. This is why heat treatments are needed to help repair low porosity hair. The heat opens the hair cuticle enabling hair to get much needed nutrients easier.
High porosity hair on the other hand, retains water. Styling products will be absorbed to enable hair to be easily nourished.
How to tell if you have High or Low Porosity
To justify in your mind whether or not you have high or low porosity hair, take a shower and observe what your hair does. As soon as your hair hits the water, be very aware of how long it takes for your hair to feel drenched. If your hair gets wet or soaked easily it’s probably highly penetrative. That means you have high porosity hair. If it not, your hair is less penetrative. When you step out of the shower to dry off, also notice your hair as it naturally air dries. High porosity hair often dries very quickly, while low porosity hair can remain wet for longer than a hour. Also, once your hair is dry, run your fingers through your hair. If hair catches on itself more than necessary and has a rough texture feeling, it is probably high porosity hair or you have a lot of split ends.
Understanding your hair porosity can really help in the styles you choose.