What does permanent waving solution do to the hair?
- Breaks disulfide bonds by a reduction reaction
- Rebuilds disulfide bonds by an oxidation reaction
- Coats the cuticle with a conditioning polymer
- Breaks peptide bonds by a hydrolysis reaction
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A. Breaks disulfide bonds by a reduction reaction
Waving solution is a reducing agent: it adds hydrogen to the disulfide bonds and breaks them so the hair can take the shape of the rod. Rebuilding the bonds by oxidation is the job of the neutralizer.
Reference: Permanent waving: reduction reaction
Which layer of the hair gives it most of its strength, elasticity and natural color?
- Cuticle
- Dermal papilla
- Medulla
- Cortex
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D. Cortex
The cortex is the fibrous middle layer; it holds the melanin and accounts for most of the hair's weight, strength and elasticity. The cuticle protects the cortex but contributes little strength and holds no pigment.
Reference: Hair science: layers of the hair shaft
Which color neutralizes unwanted orange (brassy) tones?
- Blue
- Violet
- Red
- Green
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A. Blue
Complementary colors sit opposite each other on the color wheel and neutralize one another; blue is opposite orange. Violet is the complement of yellow, so it corrects yellow rather than orange.
Reference: Haircolor: complementary colors