4.2 Chemical Hair Relaxing and Softening

4.2 Chemical Hair Relaxing and Softening

Chemical hair relaxing is a process that rearranges the structure of curly hair into a straighter or smoother form. It is the chemical opposite of permanent waving, though it shares similar principles of breaking and reforming the hair's disulfide bonds. For a Florida cosmetologist, understanding the differences between hydroxide-based and thioglycolate-based relaxers, their high pH levels, and proper neutralizing techniques is critical to prevent severe hair damage and scalp burns.

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Hydroxide Relaxers and the Chemistry of Lanthionization

The most common chemical hair relaxers are hydroxide relaxers. These are very strong alkalis with a pH range of 12.0 to 14.0. Because of their extreme alkalinity, they can swell the hair up to twice its normal diameter, allowing the solution to penetrate the cortex rapidly.

The chemical mechanism of hydroxide relaxers is fundamentally different from permanent waving. While permanent waves break and reform disulfide bonds, hydroxide relaxers break disulfide bonds permanently through a process called lanthionization.

1. The hydroxide relaxer removes one sulfur atom from a disulfide bond.
2. This chemical reaction converts the disulfide bond (which consists of two sulfur atoms) into a lanthionine bond (which contains only one sulfur atom).
3. Lanthionine bonds are highly stable and cannot be reformed. Consequently, hair treated with a hydroxide relaxer is permanently straightened and can never be permed or restored to its original curl pattern.

graph LR
    A["Disulfide Bond (S-S)"] -->|Hydroxide Relaxer Removes 1 Sulfur| B["Lanthionine Bond (S)"]
    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#bbf,stroke:#333,stroke-width:2px

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Types of Chemical Relaxers

Hydroxide relaxers are classified based on their active chemical compound:

Lye vs. No-Lye Relaxers

• Sodium Hydroxide (Lye) Relaxers: Often referred to as "lye relaxers," these contain sodium hydroxide as the active ingredient. They require no mixing and process rapidly. They are highly effective at straightening coarse hair but can cause severe scalp burns if not applied correctly.
• No-Lye Relaxers: These include guanidine, lithium, and potassium hydroxide. Guanidine hydroxide relaxers are advertised as gentler on the scalp, making them popular for home use and sensitive clients. However, they are still highly alkaline and can be extremely drying to the hair shaft due to calcium mineral buildup.
• Ammonium Thioglycolate (ATG) Relaxers: ATG relaxers utilize the same chemistry as alkaline permanent waves but in a thicker cream formulation. They operate at a pH of 9.6 to 10.0. They do not involve lanthionization and can be neutralized with an oxidizing agent. CRITICAL WARNING: Hydroxide relaxers and ATG relaxers are completely incompatible. Applying a hydroxide relaxer over ATG-treated hair (or vice versa) will cause the hair to melt and break off.

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Safety and Application Procedures

Applying relaxers requires strict adherence to manufacturer instructions and safety protocols to protect the client's skin and scalp:

1. Client Consultation and Scalp Examination: Never apply a relaxer if the client has scalp abrasions, scratches, or open sores. Do not shampoo the hair immediately prior to a hydroxide relaxer application, as this sensitizes the scalp and increases the risk of burning.
2. Base Cream Application: Hydroxide relaxers are caustic and can burn the skin. A base cream (usually petroleum jelly) must be applied to the hairline, ears, and the entire scalp to protect the skin.
   • Base Relaxers require the manual application of base cream to the entire scalp before applying the relaxer.
   • No-Base Relaxers contain a protective base built into the cream that melts at body temperature and spreads across the scalp automatically, but cosmetologists must still apply base cream around the hairline and ears for safety.
3. Application Process:
   • Virgin Relaxer: Applied to untreated hair. The solution is applied 1/4 inch to 1/2 inch away from the scalp and through the hair shaft, avoiding the porous ends until the last few minutes of processing.
   • Retouch Relaxer: Applied only to new growth (regrowth) at the scalp. Overlapping onto previously relaxed hair will cause severe breakage and thinning.
4. Smoothing: Use the back of a comb or gloved fingers to gently smooth the relaxer through the hair. Avoid combing the relaxer through, as physical tension combined with chemical swelling can snap the hair.

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The Neutralization Process

For hydroxide relaxers, neutralization does not involve rebuilding disulfide bonds. Instead, the goal is to deactivate the alkaline residues left in the hair and restore the hair's natural pH (4.5 to 5.5).

1. Rinsing: The hair must be rinsed thoroughly with warm water for several minutes to physically remove as much of the relaxer cream as possible.
2. Acid-Balanced Neutralizing Shampoo: An acid-balanced neutralizing shampoo (typically pH 4.5 to 5.5) is applied. Many of these shampoos contain a color indicator (such as phenolsulfonphthalein) that turns pink in the presence of alkali, showing the cosmetologist where relaxer residue remains. Rinsing and shampooing must continue until the lather remains completely white, indicating all alkaline chemicals have been neutralized.

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Keratin Smoothing Treatments

Keratin smoothing treatments, also known as Brazilian blowouts or keratin treatments, do not break disulfide bonds. Instead, they work by coating the hair cuticle with a protein barrier that eliminates frizz and smooths the hair shaft.

• Mechanism: The treatment solution, which often contains formaldehyde or organic acids like glyoxylic acid, is applied to the hair and blow-dried. A flat iron heated to high temperatures (usually 430°F to 450°F) is used to polymerize and seal the keratin coating onto the hair shaft.
• Florida Safety Standards: When using treatments that contain formaldehyde or formaldehyde-releasing agents, Florida salons must comply with federal OSHA standards. This includes ensuring adequate ventilation, wearing appropriate personal protective equipment (PPE) like gloves, and providing Safety Data Sheets (SDS) to employees.