Cosmetology
Cosmetology is the broadest domain: hair and scalp analysis, shampooing and conditioning, haircutting fundamentals, wet and thermal styling, hair colour, and chemical texture services, all bound by the state's sanitation and client-record rules. The exam rewards knowing what a product does at the molecular level, so expect pH and side-bond questions mixed with formula math.
Hair structure and pH
- Cuticle (protective scales), cortex (the bulk, holding melanin and bonds), medulla (often absent in fine hair).
- Hair sits at pH 4.5–5.5. Alkaline products swell the cuticle and let chemicals in; acidic products close it and add shine.
- Three side bonds: hydrogen (broken by water - wet sets), salt (broken by pH change - relaxing and colour), disulfide (broken only by thio relaxers and permanent waves). Peptide bonds are not broken by normal services.
Colour rules
- Levels run 1 (black) to 10 (lightest blonde). Colour cannot lift colour; pre-lighten first.
- Developer: 10 volume deposits only, 20 lifts about one level, 30 lifts two to three, 40 lifts three to four - more lift means more cuticle damage.
- Complementary colours neutralize (blue cancels orange, violet cancels yellow); fill before going significantly darker so the result is not muddy.
- Patch test 24–48 hours before an aniline tint; strand test for porosity and timing.
Chemical texture
- Relaxer strength (mild, regular, super) is chosen by curl resistance, not by how straight the client wants it. Base cream protects the scalp; no-base is for non-scalp retouches.
- Retouch applications go on new growth only - overlapping previously relaxed hair causes breakage.
- Process, rinse thoroughly, then neutralize with shampoo to restore pH and stop processing; follow with a reconstructive treatment, not a second chemical service.
Worked example
A level 5 client with resistant grey wants a level 7 warm brown. She needs two levels of lift plus grey coverage, so a level 7 natural/gold with 30 volume on dry hair works; 20 volume would leave her near level 6 and under-cover. Reasoning: desired level minus natural level equals the lift needed, and the lift decides the developer.
Traps that cost marks
- Using 40 volume on the scalp.
- Colouring over metallic salts or compound henna without a test.
- Overlapping relaxer onto already relaxed hair.
- Skipping the patch test or its written record.