Hair Care and Hairdressing Services
Build from structure outward
Hair questions are usually structure questions in disguise. Know the three layers - cuticle (protective scales), cortex (strength, elasticity, pigment), medulla (absent in fine hair) - and the properties analyzed in consultation: texture, density, porosity, elasticity, and growth pattern. Porosity explains why over-porous hair grabs color too dark or relaxes too fast; elasticity explains breakage risk.
Services to be able to sequence
Draping and shampooing (surfactant chemistry, pH, conditioner on mid-lengths and ends), scalp massage, haircutting (sections, guideline, elevation and angle controlling graduation and layers), blow-drying and thermal styling, and chemical services. For color, know the level system from 1 (black) to 10 (lightest blonde), developer volume as a measure of oxygen release, patch and strand tests, and why manufacturer ratios are never altered. For texture, know thio versus acid permanent waves, the neutralizer's role in rebuilding bonds, and lye versus no-lye relaxers with base cream, strand test, and neutralizing shampoo.
Traps
Mixing products from different manufacturers; overlapping a relaxer onto previously relaxed hair; assuming a higher-volume developer is always better (more lift but more damage); forgetting that a strand test, not a formula chart, predicts the outcome on this client's hair; and applying conditioner to the scalp on oily hair.
Rule of thumb
When in doubt, strand test and follow the manufacturer's mixing ratio to the letter. Worked example: a client with previously colored, high-porosity hair wants to go two levels lighter. Rather than reaching for the strongest developer, take a strand test to see how fast the hair lightens and how much breakage it tolerates, then choose the mildest formulation that reaches the target.