Illinois Cosmetology Practice Exam 2026 - Free Cosmetology Practice Questions and Study Guide

Heat styling has a significant impact on hair structure, primarily because it alters the hair's natural proteins and moisture levels. When heat is applied, particularly through tools like flat irons, curling wands, or blow dryers, it raises the temperature of the hair. This can lead to the weakening of the hydrogen bonds that give hair its shape and flexibility.

Specifically, prolonged exposure to high heat can cause splits in the cuticle, which is the outer protective layer of the hair shaft. The cuticle consists of overlapping scales; when these scales become damaged or lifted, the inner layers of the hair can become exposed to environmental elements, leading to moisture loss and increased susceptibility to breakage. As a result, the hair becomes dry, frizzy, and prone to damage, making it appear unhealthy and less vibrant.

In contrast, the other options suggest outcomes that do not accurately represent the effects of heat styling. For example, increased thickness and health are not typically associated with heat styling, as the opposite is often true—excessive heat can lead to thinning and brittleness. Enhancing natural curl patterns can be achieved with heat but does not reflect the actual structural damage heat can cause. Lastly, the claim that heat has no effect on hair structure is