Cosmetology · Basic Chemistry of Products

The natural pH of healthy hair and skin is approximately:

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Correct answer

4.5 to 5.5 (slightly acidic)

A 10.0 (alkaline)
B 2.0 (strongly acidic)
C 4.5 to 5.5 (slightly acidic)
D 7.0 (neutral)

Why this is the answer

The natural pH of healthy hair and skin is approximately 4.5 to 5.5, which is slightly acidic. This slight acidity, sometimes called the skin's 'acid mantle,' helps protect against bacteria and keeps the hair cuticle compact and smooth. Products designed to be 'pH balanced' aim to stay close to this range. Strongly alkaline products (like some relaxers) raise the pH and swell/open the cuticle, which is why an acidic neutralizing or balancing step is often needed afterward to restore the natural pH.

Source: Scientific Concepts — Natural pH of Hair and Skin

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About this topic: Basic Chemistry of Products

Basic chemistry of products covers matter, elements and compounds, pH and the pH scale, acids and alkalis, oxidation and reduction, and how these ideas explain what shampoos, colours and chemical services actually do to the hair. This is one of 9 Scientific Concepts questions on basic chemistry of products, each with a full explanation on a single study page.

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The natural pH of healthy hair and skin is approximately:

Why this is the answer

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