Hair Care: Hair Structure, Shampooing, Conditioning and Styling
Hair structure
The shaft has three parts: the cuticle, overlapping scales that protect; the cortex, keratin bundles with melanin and disulphide bonds where strength and colour live; and the medulla, a central core that is not always present. The follicle is fed by the dermal papilla, and the sebaceous gland supplies sebum. Hair sits at about pH 4.5-5.5 and is weakest when wet.
Growth cycle
Anagen is growth, roughly 2-7 years; catagen is transition, lasting weeks; telogen is rest, about three months, followed by shedding. Losing 50-100 hairs a day is normal.
Shampooing and conditioning
Wet the hair thoroughly, apply shampoo to the scalp, massage with fingertips and not nails, and rinse until the water runs clear. Shampoo surfactants, usually anionic, lift oil; conditioners are cationic and deposit on the negatively charged hair surface, smoothing the cuticle. Apply conditioner from mid-length to ends, comb through and rinse. Deep-condition weekly for dry or chemically treated hair.
Styling
Blot with a towel, detangle with a wide-tooth comb, apply heat protectant, keep the dryer moving 15-20 cm away, and keep irons around 180 degrees Celsius or lower on fine hair.
Worked example
A client washes daily and complains of greasy roots and dry ends after colouring. Reasoning: daily washing with a strong shampoo strips the scalp, and the coloured ends are porous. Recommend a gentle sulphate-free shampoo at the scalp, conditioner only from mid-length, a weekly mask, and dry shampoo between washes.
Traps that cost marks
- Scrubbing the scalp with nails.
- Applying conditioner to the roots and flattening the hair.
- Calling the cortex the protective outer layer.