Hair Coloring and Chemical Texture Services
Color theory and levels
Levels run 1 (black) to 10 (lightest blond). The color wheel drives correction: blue cancels orange, green cancels red, violet cancels yellow. Identify the natural level, the underlying pigment exposed at that level, and the target level before mixing. Underlying pigment is red at level 5, red-orange at 6, orange at 7, orange-yellow at 8.
Products and developers
Temporary color coats the cuticle; semipermanent direct dyes deposit without lift; demi-permanent uses low-volume developer and fades over roughly 20 to 30 shampoos; permanent tint uses aniline derivatives plus hydrogen peroxide to lift and deposit. Developer volume sets the action: 10 volume deposits, 20 lifts about 1 to 2 levels, 30 about 2 to 3, 40 about 3 to 4 (and many manufacturers restrict 40 to off-scalp). Lighteners lift without depositing; a toner then refines the result.
Texture services
Thio relaxers (ammonium thioglycolate) break disulfide bonds and must be neutralized. Hydroxide relaxers (sodium hydroxide or no-lye calcium hydroxide) also break bonds but are removed by rinsing and shampooing - no neutralizer, and the straightening is permanent. Perms wrap with thioglycolate, then rebuild with a neutralizer (hydrogen peroxide or sodium bromate). Patch test 24 to 48 hours before aniline tints, strand test, and follow manufacturer processing times.
Traps
'No-lye is gentler' is false; 'neutralizer is a shampoo' is false; relaxer retouch goes on new growth only; never put hydroxide relaxer on hair that has had a thio service without guidance.
Worked example: level 6 to level 8 with tint is a two-level lift, so 20 volume with an appropriate formula - not 40.