Hair Coloring and Lightening
What this domain tests
Color selection, developer choice, application order, patch and strand testing, and avoiding damage during color and lightening.
Core rules
- Hair level runs from 1, black, to 10, lightest blonde. Developer volume controls lift and deposit: 10 volume deposits, 20 lifts about one level, 30 lifts two to three, 40 lifts more but raises risk.
- Complementary colors neutralize unwanted tones: blue cancels orange, violet cancels yellow, green cancels red. Natural or neutral shades add gray coverage.
- Always patch-test according to manufacturer directions; strand-test for resistant hair or unknown history.
- Apply virgin color mid-shaft to ends, then roots, or follow the manufacturer's order; retouch only new growth to avoid overlap.
Worked example
A client at level 4 with 40 percent gray wants a level 5 ash brown. Reasoning: gray needs coverage, and ash neutralizes warmth. Choose a level 5 ash and natural mix with 20-volume developer, which deposits and provides mild lift. Apply to the new growth first because it processes faster, then pull through the mid-shaft and ends for the last few minutes. Strand-test first because gray hair can process unpredictably.
Traps
Using 40-volume for deposit-only color; overlapping lightener; skipping patch test; choosing an ash shade on hair that is already ash; not accounting for previous color.