Hair Coloring and Lightening
Color theory and the level system
Primaries are red, yellow, and blue; secondaries are orange, green, and violet; complementary pairs neutralize each other (blue cancels orange, green cancels red, violet cancels yellow). Hair is rated on a level system from 1 (black) to 10 (lightest blonde). A formula is level plus undertone - read both or the result will be muddy or too warm.
Product families: temporary color coats the cuticle; semi-permanent deposits without lifting and often needs no developer; demi-permanent uses a low-volume developer and deposits only; permanent (oxidative) color lifts and deposits; lighteners lift without depositing and are followed by a toner.
Developer volume governs lift, never processing time: 10 volume deposits, 20 volume lifts roughly one to two levels, 30 volume two to three, 40 volume three to four and is generally reserved for off-scalp application on strong hair. Mixing two developers does not add their strength.
Always patch test 24 to 48 hours before an aniline-derivative color, and strand test for porosity and timing. Retouch applications go on new growth only, with the ends refreshed in the last few minutes of processing. A filler equalizes porosity before depositing on lightened or over-porous hair. Hot roots come from scalp heat accelerating the root formula; banding comes from overlapping.
Contraindications: a history of allergic reaction, an irritated or broken scalp, hair with metallic salts or compound henna, hair with failed elasticity, and eyelash or eyebrow tinting beyond your scope.
Traps
- Color does not lift color.
- More developer volume does not mean longer processing time.
- 40 volume on the scalp is usually the wrong answer.
Rule of thumb
Level plus undertone equals formula; developer volume sets lift; the manufacturer sets the timing. Test both allergy and strand before the client is in the chair.