Chemistry & ProductsQuestion 457 of 484

The cuticle of the hair shaft responds to pH in a predictable way. Which statement is correct?

a.Alkaline products tighten the cuticle; acidic products open it
b.Both alkaline and acidic products tighten the cuticle equally
c.pH has no effect on the cuticle, only on the cortex
d.Alkaline products (pH above 7) raise/swell the cuticle, allowing chemical services like color and perms to penetrate; acidic products (pH below 7) flatten and tighten the cuticle, sealing in moisture and adding shine

Explanation

The cuticle is made of overlapping keratin scales. In an alkaline environment (color, perm waving lotion, relaxer), the scales swell and lift, allowing larger molecules to penetrate to the cortex; this is necessary for chemical service to take effect. In an acidic environment (clarifying rinse, acid-balanced conditioner, finishing toner at low pH), the scales flatten and tighten against each other, sealing the cuticle, sealing in moisture, and increasing light reflection (shine). This is why an acidic conditioning rinse is used after an alkaline service. California licensees apply both kinds of products under CCR Title 16 §979.4. Options A, B, and C contradict basic cuticle chemistry.

Law Reference: CCR Title 16 §979.4

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