Porosity is your hair's ability to absorb and retain moisture. Your hair's porosity level is determined by how your cuticle layers are laid. Your porosity level can be rated as low, normal, or high. When your porosity level is normal, your hair has no problem absorbing moisture and keeping it in, a sign of smooth cuticles. But when the porosity level is high, moisture gets in and out of the hair easily, leaving it feeling dry and frizzy. Moisture can't easily get to the hair shaft when your hair's porosity level is low, which can lead to breakage.
Normal Porosity: Cuticle layers are open enough to allow moisture to get into the hair. They also allow moisture to stay in for a longer period of time.
Low Porosity: Cuticle layers are closed (compact) and prevent moisture to get into the hair.
High Porosity: Cuticle layers are raised. Moisture gets into the hair as fast as it gets out.
The best way to test your hair's porosity level is to spray it with plain water while it's clean.
- If the water sits on top of the hair for a long time, beads up, or rolls down the hair strands, your porosity level is low.
- If the water beads sit on the hair for a few seconds then disappears, your porosity level is normal. Congratulations, your cuticle is smooth!
- If the hair absorbs the water immediately after you spray it, your porosity level is high.
Using heat (steaming the hair) is very effective when dealing with low porosity hair. I don't own a steamer because a plastic cap and a heated towel work well for me. But a steamer is a good tool to have if you struggle with low porosity hair. Have you ever steamed freshly washed hair before adding your leave-ins? Try it! Even for 10 minutes. That will help your hair accept the leave-ins faster and keep the moisture in longer after you seal it in. Or you can add your leave-ins, steam the hair for a few minutes, then seal the moisture in. I started doing that after noticing that my leave-ins were sitting on top of my hair after each wash.
Avoid acidic hair products like apple cider vinegar and Aloe Vera juice because they can further close the cuticle layers. As much as I love my coffee rinse, I had to stop doing that too because the acidity in the coffee was making matters worse. Wash your hair with warm water to keep the cuticles open. Watch your hair closely to see if a protein treatment is necessary. A protein conditioner containing amino acids can also close the cuticle layers.
When coloring your hair, it it very important that you pay close attention to how porous your hair is. Hair with high porosity will take a permanent color faster than hair with low or normal porosity. The same is true for perms and relaxers too. For those of you who like to tex-lax your hair, you need to pay attention to these details because you might get a different result with your relaxer if you don't rinse it out fast enough. Temporary hair colors will fade faster if the hair is porous as well.
References: Hairfinder.com - Wikipedia.com