There are a few things us naturals should know and porosity is definitely one of those things. Knowing your curl pattern is good but its not essential.
There are three categories for porosity 1. Low Porosity 2. Medium Porosity 3. High Porosity
What is Porosity?? Porosity is how well our hair can absorb and retain moisture. The porosity of our hair determines how well oils and moisture pass in and out of the outermost layer of our hair which is known as the cuticle. Porosity is genetics for most of us but some factors may play a part. Things such as heat treatments, exposure or chemical processing. It is important to know what your porosity is because this will help you to choose the right products for your hair type.
How do I find out my Porosity? There is two ways to find out The Slip'n'Slide Test: Take a strand of your hair and slide your finger up the strand towards the scalp, if you feel little bumps along the way this means that your cuticle is lifted and that you have high porosity. If your fingers slip smoothly, then you have low porosity hair.
The Float Test: Take a few strands from your comb or brush and drop it into a glass of water, leave for 2-4 minutes. If your hair sinks you have high porosity, if it floats you have low porosity but if its floating in the middle of the glass you have medium porosity.
(Sources Google, Cantu Beauty Uk, Naturally Curly blog)