Chemical Services and Hair Coloring
Concepts to master
Chemical services change the hair's structure and color. Know the law of color (primary, secondary, tertiary), the level system (1 black to 10 lightest blonde), and the difference between temporary, semipermanent, and permanent color. Understand developer (hydrogen peroxide) volumes and what they do, plus the role of aniline derivatives in permanent color. For texture services, know that relaxers use an alkaline agent to break disulfide bonds and that perms use a reducing agent followed by a neutralizer to reform them.
Traps to expect
Stems test the direction of pH and the purpose of the developer. Higher-volume developer lifts more and deposits less; lower volume deposits more. Another trap is the patch test and strand test: a patch test checks for allergy, a strand test predicts processing time and result. Watch for questions about overlapping relaxer onto previously relaxed hair, which causes breakage.
Rule of thumb
"Relaxers and perms are opposites on the bond." Relaxers break disulfide bonds; perms break then rebuild them. Always strand test before processing.
Worked example
A client wants to go from a level 6 to a level 8. That is two levels of lift, so a higher-volume developer with permanent color is appropriate, and a strand test should confirm timing before applying to the full head.