How is porosity defined in hair?

Porosity in hair refers to the hair's ability to absorb moisture and color. This characteristic is determined by the condition of the cuticle, which is the outermost layer of the hair shaft. When the cuticle is in good condition, it lies flat, and the hair has low porosity, meaning it is less able to absorb moisture and color. In contrast, if the cuticle is damaged or raised, the hair exhibits high porosity, which allows for more moisture and color to be absorbed easily.

Understanding porosity is crucial for hair care and coloring, as it helps in determining the appropriate products and techniques to use. For example, hair with high porosity often requires more moisturizing products to help maintain hydration, while hair with low porosity may benefit from products that help lift the cuticle for better absorption.

The other characteristics listed, such as thickness, natural curl pattern, and elasticity, though important in their own right, do not define porosity. Thickness relates to the diameter of the individual strands, curl pattern describes the shape of the hair, and elasticity refers to how much the hair can stretch and return to its original shape. Each of these aspects contributes to the overall health and appearance of hair but does not influence its porosity directly