The hair cortex, also called the cortex, is the main part of the hair shaft and lies between the outer layer (Cuticle) and the inner core (Medulla, if available). The cortex makes up the majority of hair volume and is responsible for the hair's strength, color and texture. It consists mainly of long ones keratin-Protein fibers that are arranged parallel to the growth direction of the hair and is interspersed with Melanin, the pigment that gives hair its color.
Structure and functions of the hair cortex
- Keratin : The hair cortex consists primarily of keratin, a protein-rich fiber that gives hair its strength and elasticity. Keratin molecules are linked together by disulfide bonds, which are responsible for hair's physical properties such as curl and resistance to chemical treatments.
- Melanin : There are two types of melanin in hair – eumelanin (gives hair a brown or black color) and pheomelanin (gives hair a red or blonde color). The amount and type of melanin in the hair cortex determines the natural hair color.
- Moisture : The bark plays an essential role in regulating moisture in the hair. Keratin absorbs water, which gives hair flexibility. A lack of moisture can lead to dry and brittle hair.
Importance of the hair cortex for hair treatments
- Coloring and bleaching : Chemical processes that change hair color act on the melanin molecules in the hair cortex by removing them (bleaching) or replacing them with artificial dyes.
- Hair straightening and perming : These treatments alter the disulfide bonds between the keratin molecules in the hair cortex to temporarily or permanently change the hair structure.
- Care products : Many hair care products aim to nourish and strengthen the hair cortex by moisturizing, repairing damage, or protecting against future damage.
Damage to the hair cortex
- Chemical Treatments : Excessive coloring, bleaching, or perming can damage the structure of the hair cortex, causing hair breakage and dryness.
- Heat Damage : Frequent styling with heat (blow drying, straightening, curling) can weaken the keratin structure and cause moisture loss.
- Environmental influences : UV radiation, salt water and chlorine can also damage the hair cortex and affect hair color and health.
In order to maintain the health of the hair cortex and therefore the entire hair, it is important to use gentle styling methods, use protective care products and protect the hair from extreme environmental influences.
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