Hair Care
Hair-care questions test structure, properties and the logic of product choice. You need to link what you observe, such as porosity, elasticity, density, texture and scalp condition, to a shampoo, conditioner or treatment.
Structure and properties
- Cuticle: overlapping scales damaged by friction, heat and high pH; conditioner smooths it by lowering pH.
- Cortex: keratin bundles, disulfide bonds and melanin; where perming, relaxing and colouring act.
- Medulla: central core, often absent in fine hair.
- Growth cycle: anagen (growth, years), catagen (transition, weeks), telogen (rest, about three months).
- Porosity: low porosity resists moisture and can feel product-heavy; high porosity absorbs fast but loses moisture. Elasticity: wet hair should stretch and return; poor elasticity means stop chemical services.
Scalp and selection
An oily scalp needs a clear gentle shampoo, with conditioner on mid-lengths and ends only. A dry scalp needs moisturising, sulphate-free options. Dandruff linked to Malassezia responds to anti-fungal actives; redness, crusting or patchy hair loss needs referral.
Worked example
A client's wet hair stretches and stays stretched. Reasoning: poor elasticity means the cortex is already weakened by previous lightening. A protein treatment may help temporarily, but a perm or colour now risks breakage, so the professional answer is to postpone chemical work and recommend a course of reconstructing treatment.
Traps
Applying conditioner to an oily scalp; brushing wet hair roughly; diagnosing ringworm as dandruff; treating patchy hair loss as normal.