Chemical Services (Color, Texture, Relaxing)
Color fundamentals
Learn the level system (1 black to 10 lightest blonde), tone (warm, cool, neutral), and the law of color: red, yellow, and blue are primary; mixing two primaries makes a secondary (orange, green, violet), and opposites neutralize each other. Account for underlying pigment - darker levels conceal warmth, while light levels reveal yellow through pale yellow. Always patch test aniline-derivative tint 24–48 hours ahead and strand test for timing and result.
Developers and lift
Developer volume sets the reaction: 10 volume deposits only, 20 lifts about 2 levels, 30 about 3, and 40 about 4 (and is the harshest). Choose by the client's goal and the condition of the hair, never by habit.
Texture and relaxing
Thioglycolate perms reduce disulfide bonds so hair can be wrapped and reshaped; the neutralizer (hydrogen peroxide or sodium bromate) rebuilds those bonds and lowers pH. Relaxers use sodium hydroxide (lye, very high pH) or no-lye systems such as guanidine; strength - mild, regular, super - is matched to texture and desired straightening. Base relaxers protect the scalp; no-base formulas process faster but carry more risk. Neutralizing shampoo stops the chemical action.
Traps
Overlapping relaxer onto previously relaxed hair causes breakage, and a virgin application needs different timing than a retouch. Candidates also forget that a hydroxide relaxer and a thio perm should not be combined on the same day, and that 40 volume is not automatically better.
Worked example
A level 5 client wants level 7: 20 volume lifts 2 levels, so it is the correct developer. Rule of thumb - developer volume tracks the number of levels of lift; never exceed what the hair's condition can tolerate.