What determines the porosity of hair?

Porosity refers to the hair's ability to absorb moisture and can significantly influence how hair behaves and reacts to products and styling. The cuticle layer is the outermost layer of the hair shaft, composed of overlapping, scale-like cells. Its condition directly affects porosity: a healthy cuticle layer lays flat and tightly, preventing excessive moisture loss or absorption. In contrast, if the cuticle is damaged or lifted, it allows more moisture to enter and escape, resulting in higher porosity.

This understanding is crucial for barbers and stylists when selecting products and techniques for care and styling, as hair with high porosity might need more moisturizing and protective products, while low porosity hair may require more lightweight formulas. The other choices, while they may influence aspects of hair, do not determine porosity specifically. The thickness of strands relates to overall hair texture, color treatments can affect hair health and appearance, and heat applications can lead to damage but don't inherently determine the hair's porosity.