Which perms have a pH range of 6.9 to 7.2?

• A. Alkaline perms
• B. Acid perms
• C. Exothermic perms
• D. Low/no Thio perms

Answer: (B)

The pH of the perm solution is what differentiates perm types, and mildly acidic to near-neutral conditions are the hallmark of acid perms. A pH around 6.9 to 7.2 sits just at or slightly above neutral, which is the range acid perms are formulated to use. In this environment, the reducing agent breaks disulfide bonds gently, and the neutralizer reforms them under slightly acidic conditions, yielding a controlled curl with less swelling and damage. Alkaline perms, in contrast, rely on much higher pH levels (around 9 or more) and a stronger, faster processing action; exothermic perms are typically alkaline and rely on heat to speed the reaction; low/no-thio perms use different chemistries and aren’t defined by this mildly acidic pH range. So the pH clue points to acid perms as the best match.