Chemical Texture Services (Permanent Waving and Relaxing)
Perm chemistry
Perms break disulfide bonds with a reducing agent, reshape the hair on a rod, then rebuild the bonds with a neutralizer (sodium bromate or hydrogen peroxide). Ammonium thioglycolate is alkaline (about pH 9-9.5), swells the cuticle, and processes quickly; glyceryl monothioglycolate is acid-balanced (about pH 6.5-7.2), gentler and slower. Rod size determines curl size; wrapping patterns include book, spiral, piggyback, and bricklay. Base control and tension affect root lift and frizz.
Relaxers
Sodium hydroxide (lye) is highly alkaline, fast, and effective. No-lye relaxers (guanidine, lithium, calcium hydroxide) are milder but can leave mineral buildup. Ammonium thioglycolate ('thio') relaxers are mildest and used for fine or previously processed hair. Know virgin application versus retouch (new growth only), base and protect the scalp, apply in the correct order, smooth, rinse thoroughly, then shampoo with neutralizing shampoo repeatedly until the suds stay clear.
Traps
- Trusting a timer instead of the test curl - processing time must follow hair analysis.
- Forgetting that water breaks hydrogen bonds, so hair must be blotted, not dripping, before wrapping.
- Relaxing over metallic or progressive color, or on a scalp with abrasions.
- Using a strong relaxer on fine, porous hair.
- Thinking one neutralizing shampoo is enough.
Rule of thumb
The test curl is the only clock that matters - check, then check again before you rinse.