Hair Care and Hair Services
Core concepts to master
This domain spans haircutting, styling, chemical texture services, and coloring. For cutting, know the four basic forms (solid, graduated, increase-layer, uniform-layer), the difference between elevation and overdirection, and how sectioning controls balance. For styling, understand wet vs. dry set, thermal tools, and how hydrogen bonds make temporary curl possible.
For chemical services, know the patch test (24–48 hours before aniline-derivative color), the strand test, and the difference between permanent, demi-permanent, and semi-permanent color. Permanent color lifts and deposits and requires developer; demi-permanent deposits with low-volume developer; semi-permanent stains without developer. In texture services, know relaxer strengths, base control, and the critical rule that a relaxer retouch is applied to new growth only.
Traps to watch
- Double-processing: overlapping chemicals on previously treated hair causes breakage.
- Confusing toner (deposits, no lift) with lightener (lifts, no deposit).
- Forgetting that metallic salts can react badly with color and perms - always ask about box color and henna.
- Mixing up developer volumes: 10 volume deposits, 20 lifts one level, 30 two, 40 three to four.
Rule of thumb
Analyze before you act. Texture, porosity, elasticity, and density determine product choice and processing time. When in doubt, strand test.
Worked example
A client with relaxed hair wants highlights. Because relaxer and lightener both stress the cuticle, schedule them at least two weeks apart and strand test. This avoids overlap breakage and satisfies exam safety logic.