What percentage of hair is made up of hard keratin?

• A. 50%
• B. 75%
• C. 90%
• D. 100%

Answer: (C)

Hair is primarily composed of a protein called keratin, with a significant portion being hard keratin, which provides strength and durability to the hair structure. About 90% of the hair is made up of hard keratin. This keratin is crucial because it consists of tightly packed fibers that contribute to the hair's resilience, making it less likely to break and allowing it to withstand various environmental stresses. Understanding this composition is vital for estheticians, as it influences hair care practices, treatments, and products used in maintaining hair health. The high percentage indicates that hair is predominantly structured from this tough protein, underscoring its importance in both hair health and beauty treatments.