Chemical Texture Services (Permanent Waving and Relaxing)
What this domain tests
Chemical texture services tests how perms and relaxers change disulfide bonds, how processing and neutralization work, and when hair or scalp condition makes a service unsafe.
Core rules
- Perm solution is a reducing agent that breaks disulfide bonds; the neutralizer re-forms them in the new shape.
- Ammonium thioglycolate waves are alkaline, around pH 9.0–9.5. Acid waves use glyceryl monothioglycolate and usually require heat.
- Relaxers are strong alkaline products; sodium hydroxide (lye) and guanidine (no-lye) are common. Base and no-base formulas differ in scalp protection.
- A strand test and test curl check elasticity and processing before the full service.
- Contraindications include metallic salts, open scalp lesions, and hair too damaged to withstand reduction.
Worked example
A client with fine, porous, previously bleached hair requests a perm. A strand test shows poor elasticity. The correct decision is to refuse the perm or use the mildest acid wave with heat and frequent checks only if hair remains intact. The reasoning is that reduced bonds in already damaged hair may not re-form, causing breakage.
Traps
Overlapping relaxer; insufficient rinsing; neutralizing before the wave is complete; perming over metallic salts; ignoring scalp abrasions.
Exam focus
Link the chemistry-reduction, reshaping, oxidation-to the physical result and to safety decisions.