In permanent waving, the size of the curl is determined by the

• A. Size of the rod
• B. Processing time
• C. Temperature
• D. Hair porosity

Answer: (A)

In permanent waving, the curl size is determined by the diameter of the curling rod used to wrap the hair. The rod acts as the mold that shapes the strand while the chemical re-bonds the hair, so the final circumference follows the rod’s size. A smaller-diameter rod yields tighter curls, while a larger-diameter rod produces looser waves. Processing time, temperature, and hair porosity influence how fully and evenly the hair processes and how strong the set is, but they don’t set how big the curl ends up being—the rod does.