Chemical Services: Coloring, Bleaching, Permanent Waving, and Relaxing
Consult and test first
Every chemical service starts with a consultation and hair analysis. Color and relaxers call for a patch test 24-48 hours ahead, and a strand test whenever the formula or timing is uncertain. Never proceed over metallic salts, on hair with poor elasticity, or on a scalp with abrasions.
Color
Law of color: primaries (red, yellow, blue) mix into secondaries and tertiaries. Hair levels run 1 (black) to 10 (lightest blonde). Developer volume controls lift and deposit: 10 volume deposits, 20 volume (6%) is the standard, and 30-40 volume lifts more but is harsher. Lightening removes pigment; toner re-deposits it. On a retouch, apply to new growth first, then pull through for the last few minutes.
Permanent waving and relaxing
Permanent wave: pre-wrap, apply thio or ammonium bisulfite, process as the product directs, rinse thoroughly, then neutralize. The neutralizer rebuilds disulfide bonds and is the step that makes the curl permanent. Relaxers are hydroxide (base or no-base) or thio; protect the scalp, never overlap onto previously relaxed hair, and neutralize until the indicator shows the pH is back on the acid side.
Traps
Questions swap developer volume with amount of lift, call a wave or relaxer finished before neutralization, or suggest relaxing hair that is already relaxed. Also watch for bleaching over metallic salts and skipping the patch test.
Rule of thumb
Retouch with one inch of new growth: apply relaxer to new growth only, time it, rinse fully, then neutralize until the test indicator reads clear.