Ace the Virginia Cosmetology Test 2026 – Style Your Skills and Shine Bright!

The cortex is the part of the hair that is primarily affected by chemical services because it is the inner layer that contains the majority of the hair's structure, including the fibers and proteins that give hair its strength, elasticity, and overall characteristics. Chemical services such as coloring, perming, and relaxing work by penetrating the cuticle, which is the outer protective layer, and targeting the cortex to alter its chemical composition.

As a result, processes like oxidation during hair coloring or breaking and reforming of the disulfide bonds in perming specifically focus on the cortex, which affects the color, texture, and structural integrity of the hair. The cuticle does play a role in protecting the inner layers but does not directly change or respond to chemical treatments in the same way the cortex does. The medulla, while present in some hair types, is not significantly involved in chemical services, and the styling agent is a product used to manage or shape the hair rather than a component of the hair structure itself. Therefore, the cortex is the correct answer, as it is the key area that is altered during chemical services.