Overview
Chemical services encompass hair coloring, permanent waving, and chemical relaxing — all of which alter the hair's structure or pigment through chemical reactions. Mastery of these services requires understanding the underlying chemistry (pH, bond structure, active ingredients), proper application techniques, and critical safety protocols. This guide covers all major concepts tested on the NY Cosmetology State Board Exam.
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Hair Color
Summary
Hair color services range from temporary to permanent, each interacting with the hair differently. Understanding developer volumes, color theory, and application sequences is essential for both safe and effective results.
Types of Hair Color
| Type | Penetration | Lasting Power | Requires Patch Test? |
|---|---|---|---|
| Temporary | Cuticle only | 1 shampoo | No |
| Semi-permanent | Cuticle/outer cortex | 4–6 shampoos | No |
| Demi-permanent | Partial cortex | 12–24 shampoos | No |
| Permanent (oxidative) | Full cortex | Permanent/grows out | Yes |
Developer Volumes
• 10-volume (3%) — Deposits color only; no lift; ideal for toning or going darker
• 20-volume (6%) — Most commonly used; lifts 1–2 levels while depositing color
• 30-volume (9%) — Lifts 2–3 levels; more aggressive lift
• 40-volume (12%) — Maximum lift; used with lighteners; high damage risk
Key Concepts
• Contributing pigment (underlying/remaining pigment) — The warm tones (yellow, orange, red) revealed as natural melanin is lifted; must be neutralized or incorporated into the target color
• Color correction/color removal — Process of removing artificial pigment to return hair to its natural level; complex, multi-step service
• Persulfate salts (ammonium, potassium, or sodium persulfate) — Primary active ingredients in powder/cream lighteners that accelerate decolorization
• Aniline derivatives (para-phenylenediamine/PPD) — Found in permanent oxidative color; trigger for allergic reactions; require patch test 24–48 hours before service
• Patch test — Applied behind the ear or in the antecubital fold; check for redness, swelling, or irritation at 24–48 hours
Application Sequence for Darker Shades
1. Begin at the scalp/roots first
2. Body heat at the scalp accelerates processing
3. Darker shades require less development time, so starting at roots prevents over-processing mid-shaft and ends
Key Terms
• Developer (hydrogen peroxide) — Oxidizing agent that activates permanent color and creates lift
• Melanin — Natural pigment in hair; eumelanin (dark) and pheomelanin (red/yellow)
• Level system — Scale of 1–10 measuring hair color depth (1 = black, 10 = lightest blonde)
• Toning — Depositing a cool or neutral tone to neutralize contributing pigment after lightening
⚠️ Watch Out For
• Confusing temporary (1 shampoo) with semi-permanent (fades gradually) — the Board loves this distinction
• 10-volume = no lift, not low lift — a common mistake
• Patch tests are required for permanent oxidative color only, not temporary or semi-permanent
• When going darker, start at the scalp; when doing a retouch, apply to new growth only
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Permanent Waving
Summary
Permanent waving chemically restructures the hair's disulfide bonds to create lasting curl or wave patterns. The process involves two chemical stages: reduction (breaking bonds) and oxidation (reforming bonds around the rod shape).
The Two-Step Chemical Process
#### Step 1 — Reduction (Waving Solution)
• Alkaline (cold wave) solution contains ammonium thioglycolate (ATG)
- pH: 8.2–9.6
- Adds hydrogen ions to break (reduce) disulfide bonds
- Hair conforms to the shape of the perm rod
- Produces characteristic sulfur/"rotten egg" odor (hydrogen sulfide gas)
#### Step 2 — Oxidation (Neutralizer)
• Contains hydrogen peroxide or sodium bromate
• Oxidizes and permanently reforms disulfide bonds around the rod shape
• Locks in the new curl pattern
Types of Permanent Waves
| Type | pH | Active Ingredient | Best For | Heat Required? |
|---|---|---|---|---|
| Alkaline (cold wave) | 8.2–9.6 | Ammonium thioglycolate | Normal/resistant hair | No |
| Acid wave | 4.5–7.0 | Glyceryl monothioglycolate | Damaged/color-treated hair | Yes |
Processing & Testing
• S-wave test (test curl) — Unwind a rod 1.5 turns; if a firm "S" pattern forms against the scalp, processing is complete
• Saturation point — When hair can absorb no more waving solution; continuing beyond causes over-processing
• Over-processing signs — Mushy, weak, or disintegrating hair texture
Wrapping Techniques
• Bookend (double-end paper) wrap — End papers folded over both sides of the hair ends; prevents "fish hooks" and reduces breakage at the ends
Post-Service Instructions
• Clients must wait 24–48 hours before shampooing to allow disulfide bonds to fully reharden and the wave to set completely
Key Terms
• Disulfide bonds — The strong sulfur-to-sulfur bonds in the cortex that give hair its shape; broken and reformed during chemical services
• Reduction — Chemical process of breaking disulfide bonds by adding hydrogen
• Oxidation — Chemical process of reforming disulfide bonds by removing hydrogen
• Cortex — Middle layer of the hair shaft where disulfide bonds are located
• Ammonium thioglycolate (ATG) — Active ingredient in alkaline perm solutions
⚠️ Watch Out For
• The waving solution breaks bonds; the neutralizer reforms them — never confuse the two roles
• Acid waves require heat and are for delicate/damaged hair; alkaline waves do not require heat
• The S-wave test is performed with 1.5 turns, not a full unwind
• 24–48 hours post-perm before shampooing — clients frequently ask this
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Chemical Relaxers
Summary
Chemical relaxers permanently straighten tightly curled or coily hair by breaking disulfide bonds and rearranging them in a straightened position. Proper application, timing, and neutralization are critical to prevent scalp burns and hair damage.
Types of Relaxers
| Type | Active Ingredient | pH | Base Required? |
|---|---|---|---|
| Sodium hydroxide (lye) | Sodium hydroxide | 12–14 | Yes (base cream) |
| No-lye (guanidine) | Guanidine hydroxide | ~9–11 | No (built-in protector) |
Lye vs. No-Lye Relaxers
• Lye relaxer (sodium hydroxide)
- Most effective; pH 12–14 (extremely alkaline)
- Requires base cream applied to entire scalp to prevent chemical burns
- Faster processing; more risk of scalp irritation
• No-lye relaxer (guanidine hydroxide)
- Created by mixing guanidine carbonate + calcium hydroxide
- Built-in scalp protectors; no separate base application needed
- Less irritating to scalp but can leave calcium deposits on hair
Base vs. No-Base Application
• Base relaxer — Requires protective base cream applied to entire scalp before service
• No-base relaxer — Contains built-in scalp protectors; no separate base application required
Relaxer Retouch Application
1. Apply relaxer to new growth (virgin hair) only
2. Begin at the most resistant area first (typically the nape or crown)
3. Never overlap onto previously relaxed hair — causes over-processing and breakage
Neutralizing After a Relaxer
• Neutralizing (acidic) shampoo is applied after rinsing
• Purpose: Stops the relaxing process, removes chemical residue, and restores hair pH to 4.5–5.5
• Typically requires 2–3 applications until lather turns from pink/purple to white (with pH-indicator shampoos)
Signs of Over-Processing
• Hair becomes extremely limp, mushy, or breaks off
• Caused by complete destruction of disulfide bonds
• Cannot be reversed — requires cutting and regrowth
Key Terms
• Sodium hydroxide — Active ingredient in lye relaxers; highly alkaline (pH 12–14)
• Guanidine hydroxide — Active agent in no-lye relaxers; formed by mixing two components
• Base cream — Protective petroleum-based cream applied to scalp before lye relaxer
• Neutralizing shampoo — Acidic shampoo that stops chemical action and restores pH
• New growth — Unprocessed hair growing from the scalp since the last relaxer service
⚠️ Watch Out For
• Lye = sodium hydroxide = requires base cream; no-lye = guanidine = no separate base needed
• On a retouch, apply to new growth ONLY — never the entire hair shaft
• The neutralizing shampoo stops the process AND restores pH — it serves a dual purpose
• Over-processing is permanent — no product can reverse complete bond destruction
• Never perform a relaxer on hair with scalp abrasions or open sores
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Chemical Safety & pH
Summary
Understanding pH, safety protocols, and chemical interactions is fundamental to performing chemical services without injury to the client or cosmetologist. The NY Board exam heavily tests these safety principles.
The pH Scale
```
0 ————— 7 ————— 14
ACID NEUTRAL ALKALINE
←Hair/Scalp→ ←Relaxers→
(4.5–5.5) (pH 12–14)
```
• Natural pH of healthy hair and scalp: 4.5–5.5 (slightly acidic)
• As pH rises above 7 (alkaline): Cuticle swells and opens → chemicals penetrate the cortex
• As pH drops below 4.5 (acidic): Cuticle closes and contracts
Required Tests Before Chemical Services
| Test | Purpose | When Performed |
|---|---|---|
| Patch test | Detect allergic reaction to aniline derivatives | 24–48 hours before service |
| Strand test | Assess processing time, color result, damage potential | Before full application |
| Incompatibility test | Detect metallic salts or incompatible products | Before any chemical service |
| S-wave test | Check perm processing progress | During perm processing |
Incompatibility Test
• Also called a preliminary test
• Detects metallic salts or incompatible products already on hair
• Metallic salts + chemical services = violent reactions, heat, severe breakage, or disintegration
• Must be performed before any chemical service on new clients
Why Perms and Relaxers Cannot Be Combined in One Service
• Both perm waving solution and chemical relaxers break disulfide bonds
• Combining them causes extreme over-processing, resulting in:
- Severe breakage
- Complete hair loss
- Irreversible damage
Personal Protective Equipment (PPE)
Always wear when applying chemical services:
• Chemical-resistant gloves (mandatory)
• Protective apron (recommended)
• Protective eyewear (recommended for high-risk applications)
Contraindications — When to Refuse Service
Postpone or refuse chemical services when:
• Scalp abrasions, open sores, or irritations are present
• Positive patch test result
• Metallic salt products detected on hair
• Excessive damage or breakage present
Emergency Procedures
• Chemical in client's eye:
1. Immediately flush with cool water for at least 15 minutes
2. Refer client to a medical professional
3. Do NOT attempt further treatment in the salon
4. Complete an incident report
Key Terms
• pH scale — Measures acidity/alkalinity on a scale of 0–14; 7 is neutral
• Patch test — Allergy test for aniline-derivative products; read at 24–48 hours
• Strand test — Pre-service test to evaluate hair's response to a chemical
• Incompatibility test — Preliminary test to detect metallic salts or conflicting products
• PPE — Personal Protective Equipment; gloves, apron, eyewear
• Contraindication — A condition that makes a service unsafe to perform
⚠️ Watch Out For
• 4.5–5.5 is healthy hair pH — memorize this number range exactly
• The patch test is 24–48 hours BEFORE service — not the day of
• Metallic salts + chemical services = dangerous reaction — always perform the incompatibility test on new clients
• Never perform a chemical service over scalp abrasions or open sores
• For a chemical eye exposure, flush for at least 15 minutes and always refer to a medical professional
• The incompatibility test and patch test are different tests with different purposes — know both
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Quick Review Checklist
Use this checklist to confirm you understand each critical concept before your exam:
Hair Color
• [ ] Know the four types of hair color and how long each lasts
• [ ] Memorize developer volumes: 10 (no lift), 20 (1–2 levels), 30 (2–3 levels), 40 (maximum)
• [ ] Understand contributing/underlying pigment and when it appears
• [ ] Know that permanent oxidative color requires a patch test 24–48 hours prior
• [ ] Know application sequence: start at scalp for darker shades
Permanent Waving
• [ ] Waving solution breaks disulfide bonds (reduction); neutralizer reforms them (oxidation)
• [ ] ATG is the active ingredient in alkaline perms (pH 8.2–9.6)
• [ ] Acid waves (pH 4.5–7.0) require heat and are for damaged/color-treated hair
• [ ] S-wave test: unwind 1.5 turns — look for a firm "S" pattern
• [ ] Wait 24–48 hours after perm before shampooing
Chemical Relaxers
• [ ] Lye relaxer = sodium hydroxide; requires base cream; pH 12–14
• [ ] No-lye = guanidine hydroxide; no separate base required
• [ ] Retouch = new growth only; never overlap onto previously relaxed hair
• [ ] Neutralizing shampoo stops the process AND restores pH to 4.5–5.5
• [ ] Over-processing = mushy, limp, breaking hair = irreversible
Chemical Safety & pH
• [ ] Healthy hair pH = 4.5–5.5
• [ ] Alkaline pH opens the cuticle; acidic pH closes it
• [ ] Know all four tests: patch, strand, incompatibility, S-wave
• [ ] Never combine perms and relaxers — both break disulfide bonds
• [ ] Refuse service if scalp has open sores or abrasions
• [ ] Chemical in eye: flush 15 minutes with cool water + refer to medical professional
• [ ] Always wear chemical-resistant gloves for chemical services
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Good luck on your NY Cosmetology State Board Exam! Focus on the bold terms, the "Watch Out For" sections, and review the pH scale and developer volumes until they are second nature.