Hair is made up of different layers and structures. It is the tough protein keratin that forms the strength of your hair, nails and the outer layer of skin. Keratin is a large molecule made up of smaller units called amino acids, which join to form a chain. The hair shaft is formed of three layers the medulla, cortex, and cuticle. The medulla is the deepest layer of the hair shaft, only seen in large and thick hairs. The cortex is the middle layer of the hair shaft which provides the strength, color and texture of a hair fiber. The cuticle is the outer layer of the hair shaft is thin and colorless. It serves as protection to the cortex. Ammonia is the chemical that opens the hair cuticle, the outer layer of the hair shaft, and allows the color
