Chemical Services
This domain tests chemical change: haircolor, lightening, perms, and relaxers. The exam focuses on safety sequencing, test procedures, and what happens inside the hair.
Haircolor
- Oxidative (permanent) color uses developer to lift natural pigment and deposit artificial pigment; direct dyes are nonoxidative and sit on or in the cuticle.
- Developer volume controls lift; higher volume is not better for damaged hair.
- Patch test before color, typically 24 to 48 hours per manufacturer; strand test for timing and result.
- Law of color: primary and secondary colors; complementary colors neutralize unwanted tones.
Texture services
- Perms use a reducing agent to break disulfide bonds, then a neutralizer to rebuild them; winding tension and processing time determine curl.
- Relaxers use hydroxide (lye or no-lye) to break bonds; neutralizing shampoo restores pH; protect the scalp; never overlap relaxer onto previously relaxed hair.
- Porosity and elasticity determine how fast chemicals process; previous chemical history is critical.
Worked example
A client with dark brown, previously box-colored hair wants platinum blonde. Assess history, perform a strand test, and plan multiple sessions. Reasoning: lightener must remove both natural and artificial pigment; rushing or overlapping can melt hair; incompatible products can cause unpredictable reactions.
Traps
Skipping patch or strand tests; thinking 40-volume developer is safer; leaving neutralizer on too briefly; relaxing hair previously treated with an incompatible relaxer without checking; applying color over a fresh relaxer the same day.