Hair Colour
Hair Colour
This domain tests colour theory, developer choice, patch and strand testing, application order and colour safety.
Core rules
- Hair level runs 1 (black) to 10 (lightest blonde); undertone is the warmth revealed when colour is lifted. Use the colour wheel to neutralise unwanted tones.
- Developer volumes: 10 vol (3%) for deposit or toning, 20 vol (6%) for grey coverage and 1–2 levels lift, 30 vol (9%) for more lift, 40 vol (12%) for maximum lift off-scalp only.
- Patch-test 48 hours before; strand-test to predict result, especially on resistant grey or previously coloured hair.
- Mix according to the manufacturer's ratio; apply to regrowth first on a retouch, then pull through for the last few minutes. Never mix metallic salts with bleach.
- Protect skin with barrier cream; wear gloves; ventilate; do not store mixed colour.
Worked example
A client with 40% grey, natural level 5, wants a level 5 brown. Reasoning: grey is resistant and needs coverage, but 40 vol on the scalp risks irritation. Use a permanent level 5 with 20 vol at 1:1, apply to the regrowth, process per manufacturer, then emulsify through the ends for the final minutes. Strand-test first.
Traps
- Using 40 vol on the scalp for a dark result.
- Skipping a patch test because the shade is 'natural'.
- Applying colour to broken skin.
- Lifting through previously lightened hair and causing breakage.
- Promising an exact celebrity shade from a photo.