Chemical Services: Color, Lightening, and Texture
Chemical Services: Color, Lightening, and Texture
This domain tests color theory, developer choice, patch and strand tests, lightening stages, toning, relaxers, perms, and chemical safety. The exam expects you to predict results and prevent damage.
Core rules
- Hair color levels run from 1 (black) to 10 (lightest blonde). The color wheel predicts neutralization: yellow cancels violet, orange cancels blue, red cancels green.
- Developer is hydrogen peroxide. Volume controls lift and deposit; follow the manufacturer's chart rather than guessing. Mix only in nonmetallic bowls and use fresh product.
- Patch-test according to label, usually 24 to 48 hours before color. Strand-test for timing, porosity, and previous chemical history.
- Lightening passes through stages from red to orange to yellow to pale yellow. Stop at the target and tone; do not over-lift.
- Relaxers are strongly alkaline and break disulfide bonds; neutralizer restores pH and stops processing. Perms re-form bonds around a rod.
- Contraindications: broken or inflamed scalp, recent chemical burn, metallic salts, incompatible products, and patch-test reaction.
Worked example
A client with dark regrowth and previously lightened ends requests a uniform color. You treat it as a retouch: apply to the regrowth only, process to the target, then pull through the ends for the last few minutes. You strand-test because the ends are porous. You do not apply lightener over the whole head, which would overlap and cause breakage.
Traps
Skipping the patch test; mixing developers; overlapping relaxer; coloring an irritated scalp; lifting past pale yellow; assuming a prior box color is compatible; forgetting ventilation and gloves.