6.3 Chemical Hair Relaxers & Hydroxide Neutralization

6.3 Chemical Hair Relaxers & Hydroxide Neutralization

Chemical hair relaxing reshapes curly, coily, or tightly coiled hair into a smooth, straight form. Unlike permanent waving, which imparts curl to straight hair, relaxing permanently loosens or removes natural curl patterns through powerful alkaline chemical reactions.

Chemistry of Hydroxide Relaxers & Lanthionization

Hydroxide relaxers are the strongest chemical texturizers used in cosmetology, operating at an extreme pH range of 12.5 to 14.0. The active reducing component is the hydroxide ion (OH⁻).

Hydroxide relaxers flatten hair by breaking disulfide bonds through a unique chemical reaction called lanthionization.

    DISULFIDE BOND (Cystine)                LANTHIONINE BOND
  [Sulfur] ----- [Sulfur]    ===( Hydroxide )===>    [Sulfur]
                                ( Removes 1 S )

During lanthionization:

1. The hydroxide ion attacks a covalent disulfide bond in the hair cortex.
2. The hydroxide ion permanently removes one sulfur atom from the disulfide bond (which contains two sulfur atoms).
3. The bond converts into a lanthionine bond, which contains only one sulfur atom.

Permanent Chemical Alteration

Lanthionine bonds are permanent cross-links. Because a lanthionine bond contains only a single sulfur atom, it can NEVER be re-bonded by oxidizing neutralizers or hydrogen peroxide. Hydroxide relaxers permanently alter hair structure; once lanthionization occurs, the treated hair cannot be permed or re-curled chemically.

Hydroxide Relaxer Types: Lye vs. No-Lye Formulations

Hydroxide relaxers are formulated in several chemical variations to balance straightening power against scalp comfort and hair porosity.

Lye Relaxers (Sodium Hydroxide)

Sodium hydroxide (NaOH) relaxers are traditional "lye" relaxers. They swell the hair shaft rapidly, open the cuticle completely, and penetrate the cortex to break bonds quickly. Sodium hydroxide is extremely caustic to human tissue; contact with skin or scalp causes severe chemical burns and permanent scarring if scalp protection is omitted.

No-Lye Relaxers (Guanidine & Alternative Hydroxides)

Guanidine hydroxide relaxers are recommended for clients with sensitive scalps. They are supplied as a calcium hydroxide cream base and a liquid guanidine carbonate activator. When mixed together, they react to form guanidine hydroxide. Although guanidine hydroxide causes less scalp stinging than sodium hydroxide, it causes greater protein drying and requires regular deep conditioning treatments to prevent hair brittleness.

Ammonium Thioglycolate (Thio) Relaxers & Chemical Incompatibility

Ammonium Thioglycolate (ATG) relaxers use the same active reducing agent found in permanent wave solutions, formulated at a higher concentration and thicker cream consistency with a pH of 9.0 to 9.6. Thio relaxers break disulfide bonds by adding hydrogen atoms (reduction) and require an oxidizing neutralizer (hydrogen peroxide) to reform bonds into a straight configuration.

CRITICAL EXAM WARNING: Chemical Incompatibility

Hydroxide relaxers and ammonium thioglycolate relaxers are 100% chemically incompatible.

• NEVER apply an ammonium thioglycolate perm or relaxer to hair that has been previously treated with a hydroxide relaxer (sodium, lithium, potassium, or guanidine hydroxide).
• NEVER apply a hydroxide relaxer to hair treated with ammonium thioglycolate.

Hydroxide ions completely destroy the chemical pathways required for thioglycolate reduction and oxidation. Combining these two chemicals results in immediate chemical melting of the hair shaft, catastrophic breakage, and total hair destruction.

Base vs. No-Base Relaxers & Scalp Protection

Relaxers are classified by their scalp protection requirements:

• Base Relaxers: Require the application of a protective base cream (a petroleum-based ointment) to the entire scalp, hairline, ears, and neck before applying the relaxer chemical. The base cream creates an impenetrable physical barrier preventing caustic chemicals from burning skin tissue.
• No-Base Relaxers: Contain protective oils and conditioning agents blended directly into the relaxer cream itself, which melt at body temperature to protect the scalp. However, protective base cream must STILL be applied around the client's entire hairline and ears prior to application.

Relaxer Application Procedures, Strand Testing & Neutralizing

Selecting the correct relaxer strength is essential:

• Fine / Color-Treated Hair: Mild strength.
• Normal / Medium Texture Hair: Regular strength.
• Coarse / Resistant Tightly Coiled Hair: Super strength.

Relaxer Strand Test

Before performing a relaxing service, conduct a relaxer strand test. Apply a small amount of relaxer cream to a representative section of hair in the lower occipital area. Smooth the section according to manufacturer timing, observe processing speed, check for hair breakage, and test elasticity to ensure safety.

Virgin Relaxer Application (First-Time Chemical Straightening)

1. Section dry, unwashed hair into four quadrants.
2. Apply protective base cream thoroughly to scalp and perimeter hairline.
3. Begin application in the most resistant area (usually the nape). Apply relaxer cream 1/4 inch to 1/2 inch away from the scalp, extending through the mid-shaft, while omitting the porous ends.
4. Once mid-shaft is covered, apply relaxer to the scalp area and porous ends last. (Body heat at the scalp accelerates chemical processing, while ends absorb chemicals rapidly due to porosity).
5. Smooth relaxer cream gently using the back of a comb or fingers until desired straightness is achieved.

Relaxer Retouch Application (Maintenance on New Growth)

For clients with existing relaxed hair, apply relaxer cream ONLY to the new growth area (1/4 inch from scalp up to the previously relaxed line). Do not overlap relaxer onto previously relaxed hair. Overlapping causes severe breakage, thinning, and line-of-demarcation failure.

Rinsing & Acid-Balanced Neutralizing

1. Rinse relaxer cream thoroughly with warm water for a minimum of 5 to 7 minutes to flush all physical chemical residue from hair and scalp.
2. Apply an acid-balanced neutralizing shampoo (pH 4.5 to 6.5). Hydroxide relaxers leave hair in an extremely high alkaline state; failure to neutralize completely leaves chemical residues that silently eat away at hair keratin.
3. Use a neutralizing shampoo containing a built-in color indicator. The shampoo lather turns pink in the presence of alkaline hydroxide residue and turns pure white only when all chemical residue is completely removed. Perform a minimum of three separate shampooings until lather remains pure white.