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Overview
Chemical services encompass permanent waving, chemical relaxing, hair coloring, and lightening — all of which involve altering the hair's internal structure through chemical reactions. Mastery of these topics is critical for the California State Board Exam, as they test both theoretical knowledge and practical safety protocols. Understanding the chemistry behind each service helps predict results, prevent damage, and protect both client and cosmetologist.
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Permanent Waving
How It Works
Permanent waving chemically reshapes the hair by breaking and reforming disulfide bonds in the hair's cortex. The process occurs in two stages:
1. Waving Lotion (Reducing Step): Breaks disulfide bonds so hair can be reshaped around rods
2. Neutralizer (Oxidizing Step): Re-forms the disulfide bonds in the new curled position, locking the wave permanently
Types of Permanent Waves
| Type | pH | Active Ingredient | Best For |
|---|---|---|---|
| Alkaline (Cold Wave) | 9.0–9.6 | Ammonium Thioglycolate (ATG) | Resistant, healthy hair |
| Acid-Balanced (True Acid) | 4.5–7.0 | Glyceryl Monothioglycolate | Color-treated, damaged hair |
| Thio-Free | Varies | Cysteamine/Mercaptamine | Sensitized, color-treated hair |
Key Concepts
• Alkaline perms cause the hair to swell, allowing lotion to penetrate more readily; no heat required
• Acid perms require heat to activate and cause less swelling; gentler on the hair shaft
• Thio-free perms are the gentlest option; ideal for chemically compromised hair
Wrapping Techniques
• Croquignole: Hair is wound from scalp to ends; produces tighter curl at ends, looser near scalp
• Spiral: Hair is wound along the length of the rod; produces more uniform curl from root to end
Processing & Testing
• 'S' Test: Unwind rod approximately 1.5 turns, push hair gently toward scalp — a firm 'S' shape = sufficient processing
• Under-processing: Weak, loose curl that may not hold
• Over-processing: Frizzy, weak, excessively curly or limp hair; risk of significant breakage due to excessive disulfide bond destruction
Key Terms
• Ammonium Thioglycolate (ATG): Primary reducing agent in alkaline perms
• Disulfide Bond: The strong chemical bond broken during perming and reformed by neutralizer
• Neutralizer: The oxidizing agent that re-forms disulfide bonds in the curled position
• Croquignole: Scalp-to-end wrapping technique
⚠️ Watch Out For
• Do not confuse the reducing step (waving lotion) with the oxidizing step (neutralizer) — they are opposites
• Acid perms require heat; alkaline perms do not
• Over-processing is caused by leaving waving lotion on too long, not neutralizer
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Chemical Relaxers
How It Works
Chemical relaxers permanently straighten hair by breaking disulfide bonds at an extremely high pH. Unlike perms, the bonds are not re-formed in a new position — they are converted into a different type of bond entirely.
Types of Relaxers
| Type | Active Ingredient | pH | Notes |
|---|---|---|---|
| Lye Relaxer | Sodium Hydroxide (NaOH) | 12–14 | Most effective; requires protective base |
| No-Lye Relaxer | Guanidine Hydroxide | 9.5–11 | Less scalp irritation; can dry out hair |
| Thio Relaxer | Ammonium Thioglycolate | ~8–9.5 | Lower strength; NEVER mix with lye-treated hair |
Lanthionization
• Sodium hydroxide converts disulfide bonds → lanthionine bonds
• This process is called lanthionization
• Lanthionine bonds CANNOT be reformed — straightening is permanent
Critical Application Rules
• Apply protective base cream to scalp and skin before lye relaxer (pH 12–14 can cause severe chemical burns)
• On retouch applications, apply relaxer only to new growth (virgin hair) — overlapping onto previously relaxed hair causes breakage
• Neutralizing shampoo stops chemical action and restores hair's pH to 4.5–5.5
⚠️ Watch Out For
• NEVER apply a thio relaxer immediately after a sodium hydroxide relaxer — they are chemically incompatible and cause severe breakage
• "No-lye" does not mean no risk — protective measures are still required
• The neutralizing step in relaxers = neutralizing shampoo (NOT a traditional neutralizer like in perms)
• Overlapping relaxer onto previously treated hair is the #1 cause of chemical breakage
Key Terms
• Sodium Hydroxide (NaOH): Active ingredient in lye relaxer; pH 12–14
• Guanidine Hydroxide: Active ingredient in no-lye relaxer
• Lanthionization: Conversion of disulfide bonds to lanthionine bonds by sodium hydroxide
• Lanthionine Bond: The permanent bond created after NaOH relaxer; cannot be re-formed
• Protective Base Cream: Applied before lye relaxer to prevent chemical burns
• Neutralizing Shampoo: Stops relaxer action and restores pH
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Hair Color Fundamentals
Four Classifications of Hair Color
| Type | Penetration | Duration | Notes |
|---|---|---|---|
| Temporary | Cuticle only | 1 shampoo | Rinses out; no developer needed |
| Semi-Permanent | Slightly into cortex | 4–6 shampoos | No developer; deposit only |
| Demi-Permanent | Into cortex | ~24 shampoos | Uses low-volume developer; deposit only |
| Permanent | Deep into cortex | Permanent | Uses hydrogen peroxide; can lift and deposit |
Developer Volumes
| Volume | % H₂O₂ | Use |
|---|---|---|
| 10-vol | 3% | Deposit only; slight cuticle opening |
| 20-vol | 6% | 1–2 levels of lift; standard applications |
| 30-vol | 9% | 2–3 levels of lift |
| 40-vol | 12% | Maximum lift; not for scalp use |
The Level System
• Scale of 1–10: Level 1 = black (darkest), Level 10 = lightest blonde
• Used to measure the lightness or darkness of hair, both natural and artificial
Law of Color – Primary, Secondary & Complementary Colors
• Primary Colors: Red, Yellow, Blue
• Secondary Colors: Orange (R+Y), Green (Y+B), Violet (R+B)
• Complementary Colors (Neutralizers):
| Unwanted Tone | Neutralizing Color |
|---|---|
| Orange/Brassy | Blue |
| Yellow | Violet/Purple |
| Red | Green |
Patch Test (Predisposition Test)
• Apply color product behind the ear or inner elbow
• Wait 24–48 hours before service
• Required to detect allergic reactions to para-phenylenediamine (PPD) — found in oxidative colors
• A positive reaction = do NOT perform the service
Key Terms
• Level: Measure of hair's lightness or darkness (1–10)
• Tone/Hue: The color family (warm, cool, neutral)
• PPD (Para-Phenylenediamine): Oxidative dye ingredient; most common allergen in hair color
• Patch Test: 24–48 hour skin test for allergic reaction
• 10-Volume Developer: Used for deposit-only applications
⚠️ Watch Out For
• 10-volume = deposit only; 20-volume = the standard for most permanent color with slight lift
• Always patch test 24–48 hours BEFORE service — not the same day
• Complementary colors are opposite on the color wheel — they neutralize, not enhance
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Hair Color – Applications & Techniques
Virgin vs. Retouch Application
• Virgin Application: Apply color to mid-shaft and ends first; apply to scalp (last ½ inch) last — scalp heat speeds processing, so applying last ensures even development
• Retouch Application: Apply new color only to new growth to avoid overlap and color banding
Strand Test
• Apply color to a small section of hair before full service
• Provides information on:
- Processing time
- Final color result
- How hair will react to chemicals
Highlighting Techniques
| Method | Description | Best For |
|---|---|---|
| Foiling | Individual sections isolated in foil | Precise placement, longer hair |
| Cap Method | Strands pulled through holes in a plastic cap | Short hair, diffused all-over effect |
| Balayage | Color painted freehand onto hair | Natural, sun-kissed look |
Toners
• Applied to pre-lightened hair (typically lightened to level 9–10, pale yellow to white)
• Used to neutralize unwanted tones (yellow, orange) or achieve a fashion shade
• Usually semi-permanent or demi-permanent formulas
• Requires little to no developer
Double-Process Coloring
1. Step 1 – Pre-Lightening: Bleach hair to remove natural pigment
2. Step 2 – Toning: Apply toner or color to achieve desired shade
• Used when target shade is significantly lighter than natural level
⚠️ Watch Out For
• On virgin hair, scalp area (½ inch) is applied LAST, not first
• Toners go on level 9–10 hair — applying to insufficiently lightened hair yields muddy results
• Double-process = bleach first, tone second — never reversed
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Lightening & Bleaching
How Bleach Works
• Hydrogen peroxide oxidizes and disperses melanin (natural pigment) within the cortex
• Lightening is progressive — hair passes through 7 stages of decolorization
Seven Stages of Decolorization (Darkest → Lightest)
1. Black
2. Brown
3. Red
4. Red-Gold
5. Gold
6. Yellow
7. Pale Yellow
> Hair must reach pale yellow (Stage 7) before a toner can be applied for platinum or white results.
On-Scalp vs. Off-Scalp Bleach
| Type | Form | Scalp Contact | Strength |
|---|---|---|---|
| On-Scalp (Cream Bleach) | Cream | Safe for scalp | Gentler |
| Off-Scalp (Powder Bleach) | Powder | Never on scalp | Stronger; for highlights |
Developer Rules for Bleach
• Maximum for on-scalp application: 20-volume (6%)
• Higher volumes increase risk of scalp irritation and chemical burns
Retouch Bleaching
• Apply bleach to new growth only
• Keep away from previously lightened ends (body heat + previously lightened hair = over-processing)
• Avoid scalp contact to prevent chemical burns
Key Terms
• Melanin: Natural hair pigment dispersed during lightening
• Decolorization: The removal of natural pigment from the hair
• On-Scalp Bleach: Gentle cream formula safe for scalp contact
• Off-Scalp Bleach: Stronger powder formula; highlights only
⚠️ Watch Out For
• Off-scalp (powder) bleach should NEVER contact the scalp
• Maximum developer with on-scalp bleach = 20-volume — not 30 or 40
• A retouch bleach application is applied to new growth ONLY — not overlapped onto ends
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Safety, Sanitation & Contraindications
Absolute Contraindications for ALL Chemical Services
• Scalp abrasions, open sores, lesions
• Active scalp disease (psoriasis, seborrheic dermatitis flare-ups)
• Any condition that compromises the integrity of the scalp
Personal Protective Equipment (PPE)
• Protective gloves: Always required for chemical services (coloring, perming, relaxing)
• Protective apron: Recommended to prevent chemical contact with clothing and skin
• Protects against skin sensitization, chemical burns, and harmful chemical absorption
Metallic Salt (Incompatibility) Test
When: Before any chemical service if client uses or has used home progressive color products
How:
• Mix 1 oz of 20-volume developer with 20 drops of 70-strength peroxide
• Immerse a small hair sample for 30 minutes
Results:
• Sizzling, heat, or discoloration = metallic salts PRESENT → Do NOT perform chemical service
• No reaction = safe to proceed
Developer Storage
• Store in a cool, dark place
• Keep in original, tightly sealed container
• Avoid: Light, heat, air, and metal containers
• Improper storage causes H₂O₂ to break down (release oxygen), reducing effectiveness and creating hazardous reactions
Virgin Hair
• Hair that has never been chemically treated
• Most predictable to process
• Requires different application technique than previously treated hair
Key Terms
• Contraindication: A condition that makes a specific treatment inadvisable or unsafe
• Metallic Salt Test: Test to detect incompatible metallic salts before chemical services
• PPE: Personal Protective Equipment (gloves, apron)
• Virgin Hair: Chemically untreated natural hair
⚠️ Watch Out For
• Any open wound or lesion on the scalp = stop the service — this is always an absolute contraindication
• Metallic salts + hydrogen peroxide = dangerous heat reaction — always test when in doubt
• Gloves are required even for seemingly low-risk services like tinting
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Quick Review Checklist
Permanent Waving
• [ ] Alkaline perm pH = 9.0–9.6; active ingredient = ATG
• [ ] Acid perm pH = 4.5–7.0; requires heat; best for color-treated hair
• [ ] Neutralizer re-forms disulfide bonds by oxidation
• [ ] 'S' test: unwind 1.5 turns, push toward scalp — firm S = done
• [ ] Over-processing = frizzy, weak, breaking hair
Chemical Relaxers
• [ ] Lye relaxer = sodium hydroxide, pH 12–14; requires protective base
• [ ] No-lye relaxer = guanidine hydroxide; less scalp irritation
• [ ] NaOH converts disulfide bonds → lanthionine bonds (lanthionization)
• [ ] Neutralizing shampoo restores pH to 4.5–5.5
• [ ] NEVER use thio relaxer after NaOH relaxer
Hair Color
• [ ] 4 classifications: temporary, semi-permanent, demi-permanent, permanent
• [ ] Level system: 1 (black) → 10 (lightest blonde)
• [ ] Primary colors: red, yellow, blue
• [ ] Blue neutralizes orange; violet neutralizes yellow
• [ ] Patch test: 24–48 hours before service; tests for PPD allergy
• [ ] Virgin application: scalp area applied LAST
• [ ] 10-vol = deposit only; 20-vol = standard lift and deposit
Lightening & Bleaching
• [ ] 7 stages: black → brown → red → red-gold → gold → yellow → pale yellow
• [ ] Toner applied at level 9–10
• [ ] Max developer for on-scalp bleach = 20-volume
• [ ] Off-scalp (powder) bleach = highlights ONLY, **never on scal