Hair Coloring and Lightening
What the exam tests
Color services test the law of color, developer choice, patch and strand tests, and application order. Nevada expects you to protect the scalp and predict lift versus deposit.
Core rules
- Law of color: primary colors mix to secondary; complementary colors neutralize. Blue neutralizes orange, violet neutralizes yellow, green neutralizes red.
- Developer strength controls lift and deposit: 10 volume deposits, 20 lifts about one to two levels, 30 lifts two to three, 40 lifts three to four; always follow manufacturer.
- Patch test before aniline-derivative color when required; strand test predicts timing and result.
- Virgin application: mid-shaft to ends first, then scalp area last, unless the manufacturer directs otherwise.
- Retouch: apply to new growth only; pull through for the last few minutes.
Worked example
A client with dark brown hair wants to be two levels lighter and cover gray. A 20-volume developer with a permanent color can lift modestly and deposit, while 40 volume may expose unwanted warmth and irritate the scalp. The reasoned plan is a strand test, a lower-volume formula, and a toner if warmth appears. Do not promise a result that the hair’s pigment cannot reach in one service.
Traps
Skipping the patch test; overlapping lightener; using 40 volume on the scalp by default; and neutralizing with the wrong complement.