Key Takeaways
- Chemical texture services work by breaking and reforming disulfide bonds in the cortex
- Alkaline (cold wave) perms are best for resistant hair; acid perms are gentler for damaged hair
- NEVER mix hydroxide and thio relaxers - severe damage will result
- Hydroxide-relaxed hair can NEVER be permed; thio-relaxed hair can receive a perm later
- Always apply relaxer retouch only to new growth - overlapping causes breakage
Last updated: January 2026
Chemical Texture Services
Chemical texture services permanently change the hair's internal structure to create curl (permanent waves) or straightness (relaxers). These services alter disulfide bonds in the cortex and require thorough understanding for the NIC exam.
The Science of Chemical Texturing
Hair contains different types of bonds:
| Bond Type | Strength | What Breaks It | Relevance to Styling |
|---|---|---|---|
| Hydrogen bonds | Weak | Water, heat | Wet setting, thermal styling (temporary) |
| Salt bonds | Weak | pH changes | Affected during chemical services |
| Disulfide bonds | Strong | Only chemicals | Permanent waves, relaxers (permanent change) |
Chemical texture services work by:
- Breaking disulfide (sulfur) bonds in the cortex
- Reshaping hair into new configuration (curly or straight)
- Reforming bonds in the new shape through neutralization
Permanent Wave Theory
A permanent wave (perm) adds curl to straight or wavy hair by chemically restructuring the hair.
The Perm Process:
| Step | Chemical Action | What Happens |
|---|---|---|
| Processing | Reducing agent (thio) | Breaks disulfide bonds; softens hair |
| Rinsing | Water | Removes excess waving solution |
| Neutralizing | Oxidizing agent (H₂O₂) | Reforms and hardens disulfide bonds in new shape |
Types of Permanent Waves
| Perm Type | pH | Active Ingredient | Processing | Best For |
|---|---|---|---|---|
| Alkaline (Cold Wave) | 9.0-9.5 | Ammonium thioglycolate (ATG) | Room temp; no heat | Resistant, coarse hair; strong curl |
| True Acid | 4.5-7.0 | Glyceryl monothioglycolate (GMTG) | Requires heat | Fragile, damaged, porous hair; soft curl |
| Acid-Balanced | 7.8-8.2 | GMTG with buffering | Some need heat | Damaged hair; gentle processing |
| Exothermic | Varies | Thio + activator | Self-heating | Resistant hair; faster processing |
| Endothermic | Varies | Various | Requires external heat | Heat-activated processing |
| Low-Thio/No-Thio | Varies | Cysteamine hydrochloride | Varies | Allergies to thio; sensitive clients |
Perm Rod Selection
The size and type of rod determines curl pattern:
| Rod Size | Diameter | Curl Result | Best For |
|---|---|---|---|
| Small (Gray, Blue) | Smallest | Tight, defined curls | Short hair, strong curl desired |
| Medium (Pink, Purple) | Medium | Classic curl | Average hair length, versatile |
| Large (White, Yellow) | Largest | Loose waves, body | Long hair, soft wave |
Specialty Rods:
| Rod Type | Shape | Result |
|---|---|---|
| Concave | Smaller diameter in center | Even curl distribution |
| Straight | Same diameter throughout | Consistent curl from scalp to ends |
| Spiral | Long, uniform | Corkscrew curls |
| Loop/Circle | Bendable | Custom shapes, spot perms |
Perm Wrapping Techniques
| Technique | Method | Result |
|---|---|---|
| Croquignole (Overlap) | Wrap from ends to scalp | Tighter at ends, looser at scalp |
| Spiral | Wrap in spiral along rod | Even curl from root to end |
| Piggyback/Double | Two rods per section (ends + roots) | Even curl on long hair |
| Weave | Skip strands in wrapping | Partial curl, texture |
Hair Relaxers
Relaxers permanently straighten curly or coiled hair by breaking disulfide bonds and reforming them in a straight configuration.
Types of Relaxers
| Relaxer Type | pH | Active Ingredient | Characteristics |
|---|---|---|---|
| Sodium Hydroxide (Lye) | 11.5-14 | Sodium hydroxide (NaOH) | Strongest; fastest; most effective; can irritate scalp |
| No-Lye (Calcium Hydroxide) | 9.0-11 | Calcium hydroxide + guanidine carbonate | Gentler; good for sensitive scalps; can cause dryness |
| Lithium/Potassium Hydroxide | Varies | Lithium or potassium hydroxide | Alternative hydroxide options |
| Thio Relaxer | 9.0-10 | Ammonium thioglycolate (higher concentration than perms) | Requires neutralization with oxidizer; can be reversed |
Hydroxide vs. Thio Relaxers
| Feature | Hydroxide Relaxers | Thio Relaxers |
|---|---|---|
| Disulfide bonds | Permanently broken (lanthionization) | Broken but can reform |
| Neutralization | Plain water + acid-balanced shampoo | Oxidizing neutralizer (H₂O₂) |
| Can be re-permed? | NO - never | Yes, hair can receive perm later |
| pH range | 11.5-14 (lye) / 9-11 (no-lye) | 9.0-10 |
| Compatible with? | Only hydroxide relaxers | Only thio relaxers |
CRITICAL SAFETY RULE: NEVER mix hydroxide and thio products on the same hair. This causes severe damage and breakage.
Relaxer Application Process
Virgin Relaxer Application:
- Analyze hair and scalp; perform strand test
- Apply protective base to scalp (lye relaxers) or skip (no-base formulas)
- Section hair into four quadrants
- Apply relaxer to most resistant area first (usually nape)
- Apply 1/4 to 1/2 inch away from scalp, 1/2 inch from ends
- Smooth with back of comb (do NOT scratch scalp)
- Process according to strand test and manufacturer directions
- Rinse thoroughly with warm water
- Shampoo with neutralizing/acid-balanced shampoo
- Condition thoroughly
Retouch Application:
- Apply only to new growth (1/4 inch from scalp to line of demarcation)
- NEVER overlap onto previously relaxed hair
- Overlapping causes extreme damage and breakage
Safety Precautions for Chemical Services
Before Service:
- Complete client consultation and history
- Perform strand test
- Perform patch test (color services)
- Check for contraindications (scalp irritation, recent services, metallic dyes)
- Wear protective gloves
During Service:
- Follow manufacturer's instructions exactly
- Monitor processing time carefully
- Check for signs of irritation or damage
- Maintain proper ventilation
- Never apply heat unless specified
After Service:
- Rinse thoroughly
- Apply appropriate neutralizer/conditioner
- Document service on client card
- Provide home care instructions
Contraindications for Chemical Texture Services
| Contraindication | Why | Action |
|---|---|---|
| Damaged/Over-processed hair | Cannot withstand chemicals | Refuse service; recommend conditioning |
| Scalp irritation/abrasions | Chemical burn risk | Wait until healed |
| Metallic dyes present | Dangerous reaction | Do NOT perform service |
| Recent chemical service | Overlapping damage | Wait appropriate time |
| Low elasticity | Hair will break | Refuse service |
| Positive strand test | Hair damaged during test | Do NOT proceed |
The Neutralization Process
Neutralization is the final step that reforms and locks disulfide bonds in their new configuration.
For Perms:
- Blot excess solution from rods
- Apply neutralizer (usually contains hydrogen peroxide)
- Process for 5-10 minutes
- Remove rods carefully
- Apply remaining neutralizer to ends
- Rinse thoroughly
For Hydroxide Relaxers:
- Rinse thoroughly with warm water
- Shampoo with neutralizing (acid-balanced) shampoo
- This normalizes pH and helps close cuticle
- No oxidizing neutralizer needed
For Thio Relaxers:
- Rinse thoroughly
- Apply oxidizing neutralizer
- Process according to directions
- Rinse again
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Test Your Knowledge
Which type of permanent wave is BEST suited for fragile, damaged, or previously color-treated hair?
A
B
C
D
Test Your Knowledge
What is the PRIMARY difference between hydroxide relaxers and thio relaxers?
A
B
C
D
Test Your Knowledge
When performing a relaxer retouch, the product should be applied:
A
B
C
D
Test Your Knowledge
A client has previously used metallic/compound hair dye. You should:
A
B
C
D