Hair porosity is one of those tricky little descriptors that can play a big role in the overall feel and appearance of your hair. But most people don’t really know where they fall on the porosity spectrum—are they low porosity, high, or somewhere tucked in between? “Hair porosity describes how the hair’s cuticle absorbs and holds on to moisture in its pores—hence, the term porosity,” says hairstylist Miko Branch, co-founder of hair care brand Miss Jessie’s. So when you have high porosity hair, that means it’s, well, high on the porosity spectrum: meaning it’s very porous, and thus the cuticles are more sparse than they are dense, so it’s able to absorb a lot of water. In contrast, you can have low porosity hair: “When someone has low porosity hair, the hair tends to have trouble absorbing moisture because the hair is resistant to water,” says Malary. “When the hair has low porosity, the cuticles are packed so tightly onto each other, it makes it very difficult for moisture or water to penetrate the strand.”
