Chemical Services: Permanent Waves, Relaxers, and Color
What this domain tests
Chemical items test the relationship between pH, bond structure, and product choice; test procedures; and the safety checks that must precede any relaxer, wave, or color.
Permanent waves and relaxers
Hair shape is held by disulfide bonds in the cortex. A permanent wave wraps hair on rods, applies a reducing agent (commonly ammonium thioglycolate), rinses, then applies a neutralizer (hydrogen peroxide or sodium bromate) to rebuild bonds in the new shape. A relaxer uses a strong alkaline agent - sodium hydroxide (lye, pH around 12–14) or calcium hydroxide with guanidine (no-lye) - to break bonds and straighten. Both require a patch test and strand test per manufacturer directions, gloves, and a porosity check.
Color
- Temporary color coats the cuticle; semipermanent deposits without lifting; demi-permanent uses low-volume developer; permanent color lifts and deposits.
- Developer volume controls lift: 10 volume deposits, 20–30 lifts with color, 40 provides maximum lift.
- Law of color: primary colors combine into secondary and neutral tones; complementary colors neutralize unwanted tones.
- Patch test 24–48 hours before color for clients with no prior exposure.
Worked example
A client with previously relaxed hair requests a permanent wave. Reasoning: relaxed hair is already chemically altered and often porous; a thioglycolate wave on relaxed hair can overprocess and break it. Check elasticity and porosity, review the relaxer date, and if the hair is fragile, decline the service or use a compatible product only as the manufacturer allows.
Traps
- Overlapping relaxer onto previously relaxed scalp.
- Rinsing or neutralizing too early, leaving hair underprocessed.
- Skipping the patch test because the client "never reacted before."
- Assuming semipermanent color can lighten hair.