Hair Care and Hairdressing
Hair care and hairdressing questions test whether you can read the hair and scalp before choosing a product or service. Expect hair structure, growth cycles, shampoo and conditioner chemistry, draping and styling safety, and recognition of when to stop.
Core rules
- The hair shaft has three layers: cuticle (protective outer scales), cortex (strength, elasticity, pigment), and medulla (central core, often absent in fine hair). Chemical services act mainly on the cortex after lifting the cuticle.
- Hair grows in anagen (active), catagen (transition), and telogen (resting and shedding) phases. Average scalp growth is about half an inch per month, but rate varies.
- Assess porosity, elasticity, density, and scalp condition. High porosity takes color quickly and loses moisture quickly; low porosity resists absorption.
- Shampoo surfactants lift oil and soil; conditioners are acidic and smooth the cuticle. Water that is too hot strips color and oils.
Worked example
A client with lightened, rough-feeling hair asks for a strong clarifying shampoo and hot-water rinse. The reasoning points to high porosity and a compromised cuticle: clarify only if needed, use a gentle low-pH conditioner, lower water temperature, and avoid overlapping chemical services until elasticity improves.
Traps
Equating oily with needing hot water; using heavy protein on hair that is already brittle; ignoring a scalp lesion; and assuming every client can receive the same shampoo pressure or massage.