Georgia Cosmetologist License Practice Exam

The primary difference between permanent and semi-permanent hair dye lies in how they interact with the hair structure. Permanent dye is designed to penetrate the hair shaft, allowing the color to become a long-lasting part of the hair itself. This deep penetration typically involves a chemical process that opens the cuticle layer of the hair so that the dye can deposit into the cortex, providing a more durable and vibrant color change that can withstand washing and fading over time.

In contrast, semi-permanent dyes generally coat the outer layer of the hair without heavily altering its internal structure. They use smaller molecules that can slightly penetrate the cuticle but do not reach the cortex in the same way as permanent dyes. This means that while semi-permanent dyes can offer a color change, they tend to wash out more gradually and do not provide the same level of longevity as permanent dyes since they are designed to fade after a number of washes. Therefore, understanding the way these different dyes interact with the hair is crucial for making informed decisions about hair coloring techniques and achieving desired results.