Which layer of the hair contains the melanin that gives hair its natural color?

The cortex is the middle layer of the hair shaft and contains the melanin (pigment) that gives hair its natural color, as well as providing most of the hair's strength and elasticity. Chemical services such as haircolor and perms work primarily within the cortex, which is why the cuticle must be opened to allow products to reach it. The cuticle is the protective outer layer, and the medulla is the innermost core. Understanding that natural color and chemical changes center on the cortex is frequently tested.