What term describes hair that has difficulty absorbing color?

The term that describes hair that has difficulty absorbing color is porosity. When hair is described as having low porosity, it means that the cuticle layer is tightly packed, preventing color molecules from easily penetrating the hair shaft. Hair with low porosity often appears shiny and can resist moisture, making it challenging for color to be absorbed consistently. Consequently, coloring processes can be less effective, and achieving the desired shade may require additional techniques or products to facilitate better absorption.

In contrast, density refers to the number of hair strands per square inch on the scalp, elasticity measures how much the hair can stretch and return to its original length without breaking, and texture describes the thickness or diameter of each individual hair strand. While these aspects can influence how hair looks and behaves, they do not specifically relate to the hair's ability to absorb color like porosity does.