What is the outer layer of the hair fiber known as?

The outer layer of the hair fiber is known as the cuticle. The cuticle serves as the protective barrier for the inner layers of the hair, which include the cortex and medulla. It consists of overlapping, scale-like cells that are tightly packed together, much like shingles on a roof. This structure helps to protect the hair from damage and environmental factors, such as UV rays and pollution. The health and integrity of the cuticle are crucial for maintaining the overall strength, shine, and smoothness of the hair.

In terms of hair health and treatment, understanding the role of the cuticle is essential for selecting the right products and techniques for coloring, styling, and maintaining hair. A damaged cuticle can lead to issues like frizz, split ends, and increased porosity, which may affect how hair color is absorbed and retained.