Chemical Texture Services: Permanent Waving and Relaxing
The chemistry
Permanent waving and relaxing both act on disulfide bonds in the cortex. A reducing agent breaks those bonds; the hair is then shaped on rods (wave) or smoothed (relaxer); an oxidizing neutralizer rebuilds the bonds in the new shape.
- Alkaline wave (ammonium thioglycolate, pH about 7.8 to 8.2): faster, stronger, more cuticle swelling.
- Acid wave (glyceryl monothioglycolate, pH about 6.9 to 7.2): gentler and slower.
- Relaxers: sodium hydroxide (lye, pH 12 to 14) is fast and effective but harsh; no-lye guanidine or lithium hydroxide is gentler on the scalp but can leave mineral buildup; ammonium thioglycolate (thio) relaxers use the same chemistry as wave lotion and require a neutralizer.
Procedure logic
Analyze scalp and hair (porosity, elasticity, previous chemical history). Protect skin with base cream where the product requires it. Do a test curl or test area, respect the manufacturer's processing time, rinse thoroughly, then neutralize or shampoo with neutralizing shampoo and follow with a low-pH conditioner. In a retouch, apply product only to new growth; relaxer is never pulled through previously relaxed hair.
Contraindications and safety
Do not wave or relax hair that is damaged, excessively porous, or has had incompatible recent chemical services without a strand test. Metallic salts and certain medications (including isotretinoin) are red flags. Never mix products, never reuse leftover product, and wear gloves.
Traps
Thinking the neutralizer reduces bonds rather than rebuilding them; assuming a relaxer and a color service always happen on the same day; confusing base and no-base relaxers.
Rule of thumb
New growth only on a retouch, and when in doubt, strand test: a small test tells you more than a guess about the whole head.