Hair and Scalp Care, Shampooing, and Conditioning
Structure and growth
The follicle, bulb, and papilla anchor the hair; the shaft has a cuticle (protective scales), cortex (bulk, melanin, disulfide bonds), and, in coarser hair, a medulla. Sebaceous glands supply sebum and sudoriferous glands produce sweat. Growth cycles are anagen (active), catagen (transition), and telogen (resting and shedding); losing roughly 50 to 100 hairs a day is typical.
Scalp and hair analysis
Before wetting the hair, examine the scalp for abrasions, eruptions, redness, swelling, lice or nits, and unidentified lesions. Infectious or parasitic conditions and unidentified lesions are referred to a physician: a cosmetologist may shampoo, cut, and style but cannot treat disease. Noninfectious flaking may be dry scalp or pityriasis; oily flaking suggests seborrheic dermatitis. Assess porosity (does hair absorb and hold water?), elasticity (stretch and return), and density.
Shampooing and conditioning
Shampoo chemistry is built on surfactants, which lift oil and debris so water can rinse them away. Formulas vary: clarifying, balancing, moisturizing, medicated, and dry or waterless. Water temperature should be moderate, since hot water irritates the scalp and accelerates color fading. Scalp massage manipulations (effleurage, petrissage, tapotement, vibration) should be slow and rhythmic and are contraindicated over irritated skin or a recent chemical service. Conditioners work at different levels: instant rinse-out (surface), normalizing (adjusts pH), and deep treatment (penetrates the cortex); leave-in products add protection and are not rinsed out.
Traps
Assuming a medicated shampoo cures a scalp disease; massaging a scalp with an open lesion; labeling all flaking as dandruff; using very hot water and then blaming the shampoo for fading color.
Rule of thumb
Analyze first, then choose: if the scalp is inflamed, stop and refer; if the hair is porous or fragile, choose the gentlest formula and lower the water temperature.