Colouring and chemical texture services
Colouring and chemical texture services
This domain tests colour theory, developer choice, test procedures and chemical safety for colour, perming and relaxing. The exam expects you to calculate risk and predict outcome, not just name products.
Core rules
- Patch test according to manufacturer instructions before oxidative colour, even if the client has been coloured before.
- Strand test for porosity, elasticity and colour result, especially on resistant, grey or previously chemically treated hair.
- Developer peroxide volume affects lift and processing; follow the manufacturer's ratio exactly.
- Lightening exposes warmth; tone with the opposite colour on the colour wheel.
- Perming breaks disulphide bonds and neutraliser rebuilds them; do not perm over bleached or freshly relaxed hair.
- Never mix peroxide with metallic salts or unknown products; check history.
Worked example
A client with 50% grey wants a cool light brown. The stylist chooses a base shade for grey coverage plus a cool modifier, uses the correct developer for the target level, strand-tests, and applies mid-lengths to ends before the resistant grey at the front. Reasoning: grey hair is resistant and lacks pigment, so coverage and tone need separate control; overlapping can over-process.
Traps
Skipping a patch test because 'the client is a regular'; using a stronger developer to speed up; overlapping bleach; neutralising too early; perming over hair that fails the elasticity test; ignoring scalp reactions.