Did you know a strand of human hair has four main layers? The cuticle (outermost layer), the cortex (protein-rich layer), the medulla (innermost), and a cell membrane complex that glues the layers together. And you gotta take good care of every layer!
Your hair’s porosity is determined by your cuticle layer which is made up of “shingles” that overlap like a roof or pinecomb. When the shingles are close together, evenly layered and flat your hair is considered “low porosity”. When the cuticle is chipped, uneven, raised or missing your hair is considered “high porosity”.