Hair Coloring
Levels, tones, and undertone
Learn the level system (1 black through 10 lightest blonde) and the difference between base color (the dominant tone) and undertone (the warmth revealed as melanin is removed). Natural melanin is eumelanin (brown/black) and pheomelanin (red/yellow). As you lighten, the undertone progresses red → red-orange → orange → orange-yellow → yellow → pale yellow.
Categories of color
- Temporary - large molecules, coat the cuticle, shampoo out.
- Semipermanent - no lift, deposit only, fades over several shampoos.
- Demipermanent - deposit only, low-volume developer (often 10 volume), mixed with peroxide developer.
- Permanent - aniline derivatives plus developer penetrate the cortex; lifts and deposits; requires a patch test per manufacturer.
Developer math
20 volume (6%) deposits and lifts slightly; 30 volume (9%) lifts more; 40 volume (12%) lifts the most and is harshest on the scalp. Developer is not the color - it is the engine.
Contraindications and traps
Do not color a scalp that is broken, irritated, or diseased; refer. Metallic-salt or henna products can react violently with peroxide - refuse or proceed only with great caution. Never lighten over freshly relaxed hair on the same day. "Semipermanent colors lift" is false. "Aniline derivatives are in all colors" is false - they are in permanent color.
Worked example
A level 6 client wants to be a level 9. She needs three levels of lift: choose permanent color with 30 volume (one to two levels) plus lightener, or lightener to pale yellow followed by a toner. Test a strand first; if the strand shows orange, you have lifted two levels, not three.