Wisconsin Cosmetology Practice Exam 2025 – The All-in-One Guide to Master Your Certification!

Hair color application primarily affects both the cuticle and cortex of the hair. The cuticle is the outermost layer of the hair shaft, consisting of overlapping cells that protect the inner layers. When hair color is applied, it needs to penetrate this outer layer to be effective, allowing the color to reach the cortex, which is the layer that contains the pigment and determines the hair's color.

The cortex is crucial because it contains the melanin that gives hair its natural color. Hair dye works by either lifting the existing pigment or depositing new pigment into the cortex. Therefore, for the color to bond properly and achieve the desired result, it must impact both the cuticle and cortex.

The medulla, which is the innermost layer of hair, is often not involved in the coloring process and does not directly contribute to hair's pigment. Similarly, the hair follicle is not influenced by the application of color, as it is the living part of the hair located beneath the scalp and does not come into contact with hair dye.

Thus, the correct choice highlights the specific areas of the hair that are significantly impacted during the coloring process.