
Hair structure affects how colour is absorbed and retained. Understanding this helps you adjust formulas and timing for consistent results.
Key points:
Hair Layers: Cuticle, cortex, and medulla. Colour penetrates the cortex; the cuticle protects it.
Porosity Levels: Low, medium, high. Porosity determines how quickly hair absorbs colour.
Low Porosity: Resistant, may require longer processing or pre-treatment.
High Porosity: Absorbs quickly but may fade faster; use conditioners and bond protectors.
Hair Condition: Previous chemical treatments affect colour uptake. Always assess hair history.
Exercise:
Test and record the porosity of two different hair types (e.g., fine vs. thick hair).
Suggest an appropriate colouring strategy for each.
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