New York State Cosmetology Practice Exam 2026 – The All-in-One Guide to Master Your Certification!

Glycerin is well-known for its moisturizing properties, and this is why it is the correct answer. It is a humectant, which means it has the ability to attract and retain moisture from the environment and the air into the hair. When used in hair products, glycerin helps to hydrate the hair and scalp, making it softer and more manageable. This moisture retention is critical for maintaining healthy hair, especially for those with dry or curly textures.

Petrolatum, while it can provide a barrier to moisture loss, does not actively attract moisture to the hair or skin, which differentiates it from glycerin. Sodium sulfate is primarily used as a cleansing agent and does not have significant moisturizing qualities. Silicone can provide a protective coating that adds shine and reduces frizz but does not offer the same level of moisture absorption or retention as glycerin does. Thus, the unique properties of glycerin make it an essential ingredient in many moisturizing hair products.