Which is NOT a factor to consider when selecting perm rod size?

• A. Hair density across the scalp
• B. Desired curl pattern
• C. Hair length and diameter
• D. Porosity

Answer: (B)

Choosing perm rod size is about shaping the curl you want. The diameter of each rod sets how tight or loose the curl will be, so the desired curl pattern should guide the overall rod size plan across the head. Hair density influences how many rods you wrap in a given area and how evenly the curl will form; dense hair can require different sectioning to avoid gaps and over-concentration. Hair length and diameter affect wrapping technique and how many sections fit, which also changes the final curl. Porosity affects how deeply the perm solution penetrates and how the curl sets, influencing processing needs and the stability of the result. Since the intended curl pattern drives the rod size choice, that factor is indeed important to consider; treating it as not a factor would miss a critical part of achieving the desired outcome.