Hair Care and Hair Services
Structure and growth
Build answers from the hair's anatomy: cuticle (protective scales), cortex (strength, elasticity, pigment), medulla (may be absent in fine hair - a favorite trick). Know the growth cycle: anagen (active), catagen (transition), telogen (resting/shedding), plus the idea that hair grows roughly half an inch a month.
Analysis before service
Every chemical service begins with a consultation and hair analysis: texture, density, porosity, elasticity, and scalp condition. Low porosity resists moisture; high porosity loses it and accepts chemicals fast. Poor elasticity means no chemical service today.
Chemistry of services
Shampoo is a surfactant system; conditioner lowers pH and smooths the cuticle. In color, know the level system (1 darkest to 10 lightest), the law of color, and developer strengths: 10 volume deposits, 20 volume lifts up to two levels, 30 volume two to three, 40 volume three to four. Aniline-derivative tints require a patch test 24–48 hours before service. Relaxers are strongly alkaline (roughly pH 12–14) and must be neutralized; thio relaxers and hydroxide relaxers behave differently, and hydroxide relaxers are not compatible with thio.
Traps
Questions misstate developer volume as a color level, claim the medulla is always present, or suggest a patch test right before the service. Also watch for thermal-styling safety (test iron temperature, never on a wet client's hair) and for license scope - know what your Ohio license lets you perform.
Rule of thumb
If the hair floats (high porosity) or snaps instead of stretching (poor elasticity), the answer is usually treatment and rebook, not a stronger chemical.