pH Scale — Key Products
| pH Range | Type | Products |
|---|
| 0–2 | Strong Acid | Acid waves (thio), some treatments |
| 3–4 | Acid | Conditioners, acid rinses, toners |
| 4.5–5.5 | Slightly Acid | Hair & skin's natural pH |
| 6–7 | Near Neutral | Shampoos (designed for daily use) |
| 7 | Neutral | Pure water |
| 8–9 | Alkaline | Permanent hair color, most shampoos |
| 9–11 | Alkaline | Thio relaxers, cold wave perms |
| 12–14 | Strong Alkaline | Lye (sodium hydroxide) relaxers |
Alkaline = opens cuticle (processes faster). Acidic = closes cuticle (smooths, seals). Hair and skin are naturally slightly acidic.
Developer Volumes
| Volume | H₂O₂ % | Lift | Use |
|---|
| 10 vol | 3% | 0 lift | Deposit-only, toners, refresh color |
| 20 vol | 6% | 1–2 levels | Standard permanent color, gray coverage |
| 30 vol | 9% | 2–3 levels | Lightening dark hair, high-lift color |
| 40 vol | 12% | 3–4 levels | Maximum lift; only with lightener or HLT |
Higher developer = more lift BUT more damage to the cortex. Never exceed manufacturer's recommended developer volume.
Level System
1 (Black) → 2 (Darkest Brown) → 3 (Dark Brown) → 4 (Brown) → 5 (Med Brown) → 6 (Dark Blonde) → 7 (Med Blonde) → 8 (Light Blonde) → 9 (Very Light Blonde) → 10 (Lightest Blonde)
Color Theory & Neutralizing Pairs
| Color Type | Colors |
|---|
| Primary | Red, Yellow, Blue |
| Secondary | Orange (R+Y), Green (Y+B), Violet (R+B) |
| Tertiary | Mix of primary + adjacent secondary |
| To Neutralize | Use |
|---|
| Orange/Brassy | Blue toner/shampoo |
| Yellow | Violet/purple toner |
| Red | Green |
| Green (pool hair) | Red/pink treatment |
Warm tones: red, orange, gold. Cool tones: ash, blue, green. Complementary colors (opposites) neutralize each other.
Hair Growth Cycle & Structure
| Phase | Duration | What Happens |
|---|
| Anagen | 2–6 years | Active growth; 85–90% of hairs |
| Catagen | 2–3 weeks | Transition; growth stops |
| Telogen | 2–4 months | Resting; hair sheds |
Hair Shaft Layers
| Layer | Function |
|---|
| Cuticle (outer) | Protection; overlapping scales |
| Cortex (middle) | Strength, color, elasticity |
| Medulla (inner) | Soft core; absent in fine hair |
Infection Control Hierarchy
| Level | Method | Destroys |
|---|
| Sterilization (highest) | Autoclave steam | ALL organisms including spores |
| Disinfection | EPA-registered disinfectant (10 min) | Most pathogens (not spores) |
| Sanitation (lowest) | Washing with soap & water | Reduces microorganisms to safe level |
Key rules: Antiseptics = for skin. Disinfectants = for tools. Porous implements (emery boards, neck strips) must be discarded after each use.
Contraindications Quick Reference
- Tinea capitis / Tinea barbae — REFUSE service; refer to physician
- Pediculosis capitis — REFUSE service; send client home
- Open cuts or abrasions — REFUSE chemical service; avoid irritants
- Scalp sensitivity — patch test 48 hours before color service
- Poor elasticity — CONTRAINDICATION for perms/relaxers (hair will break)
- Hydroxide relaxer + thio perm — INCOMPATIBLE; never do both
- Pregnant clients — use caution with chemicals; suggest professional guidance
- Allergy history — always patch test; document in client record
Always perform a patch test (skin test) 24–48 hours before applying oxidative hair color. Document and keep client records.
Chemical Service Summary
| Service | Step 1 (Reduction) | Step 2 (Oxidation) | Notes |
|---|
| Permanent Wave | Thioglycolate waving lotion breaks disulfide bonds; hair reshapes on rods | Neutralizer (H₂O₂ or bromate) reforms bonds in new shape | Under-processing = weak curls; Over-processing = damage/breakage |
| Lye Relaxer | Sodium hydroxide (pH 12–14) permanently breaks and straightens bonds | No separate neutralizer; thorough rinsing + neutralizing shampoo | INCOMPATIBLE with thio perm; strongest relaxer |
| No-Lye Relaxer | Guanidine hydroxide (pH ~10–11); gentler than lye | Neutralizing shampoo required | Less irritating but may leave calcium deposits |
| Permanent Hair Color | H₂O₂ (developer) oxidizes and swells cuticle; color penetrates cortex | Melanin oxidized; artificial pigment deposits | Higher developer = more lift; 20vol is standard |
Skin test (patch test): Required 24–48 hours before any oxidative color service. Apply small amount to inner elbow or behind ear. Check for redness, swelling, itching = positive reaction = do NOT proceed.