California Cosmetology Written ExamChemical Texture ServicesHard
A client wants to switch from a sodium hydroxide relaxer to a guanidine hydroxide ('no-lye') relaxer, believing it will be gentler on the scalp. Which statement about the pH levels of these two relaxer types is most accurate?
- AGuanidine hydroxide relaxers typically have a lower pH (about 10-11) than sodium hydroxide relaxers (which can reach pH 13-14), but can still cause irritation or dryness
- BSodium hydroxide relaxers have a lower pH than guanidine hydroxide relaxers
- CBoth relaxer types have identical pH levels near neutral (pH 7)
- DGuanidine hydroxide relaxers always have a higher pH than sodium hydroxide relaxers
Show answer & explanationAnswer & explanation
Correct answer: A. Guanidine hydroxide relaxers typically have a lower pH (about 10-11) than sodium hydroxide relaxers (which can reach pH 13-14), but can still cause irritation or dryness
Guanidine hydroxide (no-lye) relaxers generally have a lower pH (roughly 10-11) than sodium hydroxide relaxers (which can range up to pH 13-14), making them somewhat milder on the scalp, though they can still cause dryness, buildup, or irritation and are not risk-free.
Why the other options are wrong
- B. This also reverses the correct relative pH relationship.
- C. Both relaxers are strongly alkaline, far from neutral pH.
- D. Reverses the actual relationship; guanidine hydroxide is generally lower pH.
Relaxer pH Comparison
Sodium hydroxide relaxers are highly alkaline (up to pH 13-14) while guanidine hydroxide ('no-lye') relaxers are somewhat lower (pH ~10-11) but still strongly alkaline.
- No-lye ≠ no risk; can still cause dryness/buildup
- Sodium hydroxide is the strongest, most alkaline relaxer type
- Both types work via lanthionization, not thio's reduction/reformation
Memory trick: Lye is the strongest 'high' on the pH scale; no-lye is a notch lower but not neutral.