In permanent waving, curl size is determined by the rod's

• A. Rod diameter
• B. Hair length
• C. Scalp size
• D. Curl pattern

Answer: (A)

Curl size in a perm comes from the diameter of the perm rod. The rod acts as a mandrel around which the hair is wound and then chemically altered to take its shape. A larger rod creates a bigger wrap around the hair, resulting in looser, larger curls; a smaller rod produces tighter, smaller curls. Hair length can affect how the sections wrap and how the overall look sits, but it doesn’t set the curl diameter. Scalp size isn’t what determines curl size, and curl pattern is more about how the hair is wrapped and processed, with rod diameter still being the primary factor.