Hairdressing: Colouring and Chemical Texture Services
Colouring and Chemical Texture Services tests the chemistry behind safe colour, bleach, perming and relaxing: colour theory, developer choice, patch and strand tests, application order, and neutralisation.
Core rules
- Patch test colour products 48 hours before first use or after a gap, following the manufacturer; record the result.
- Assess hair porosity, elasticity and previous treatments. Do not perm or relax hair that fails an elasticity test or has incompatible history.
- Developer strength and contact time drive lift and deposition; more developer is not a shortcut. Virgin tint applies mid-lengths to ends first, then root area, unless the manufacturer says otherwise; retouch applies to regrowth first.
- Perm lotion breaks disulphide bonds; the neutraliser reforms them into the new shape. Rinse and blot before neutralising.
Worked example
A client with 3 cm of regrowth and faded mid-lengths wants a retouch. Reasoning: the regrowth needs the full development time; previously coloured hair is more porous and takes colour faster. Apply to regrowth, time it, then emulsify through mid-lengths and ends for the last few minutes, checking visually.
Traps
Overlapping colour, using metal bowls with bleach, skipping strand tests, assuming a patch test predicts strand results, and neutralising a perm before thorough rinsing. Also do not mix brands or developers without manufacturer approval.