What percentage of hair is comprised of hard keratin?

• A. 80%
• B. 90%
• C. 75%
• D. 95%

Answer: (B)

The correct answer is 90%, as this figure accurately represents the percentage of hair that is made up of hard keratin. Hard keratin is a fibrous structural protein that provides strength, durability, and resistance to environmental factors. It is a key component in the composition of hair, making it predominantly resilient and able to withstand various forms of stress.

This high percentage emphasizes the significance of hard keratin in forming the structure of hair, affecting its appearance, texture, and overall health. While other types of keratin exist, such as those found in skin and nails, hair’s composition is primarily determined by this hard keratin, which is crucial for maintaining the hair's integrity and functionality.

Understanding the composition of hair helps estheticians grasp how to better care for and treat different hair types, contributing to more effective hair care and treatment strategies.