What effect does using too much hair on a rod have when perming?

Using too much hair on a rod during the perming process can lead to an uneven curl pattern. This occurs because each section of hair must have an equal chance to be wrapped tightly and uniformly around the rod. When excess hair is used, some strands may not receive adequate tension or saturation with the perming solution. This uneven distribution can result in certain areas curling more than others, leading to a less uniform appearance overall.

In contrast, over-processed hair, faded color, and excessive frizz are issues that can arise from other factors such as improper timing, inappropriate chemical products, or lack of proper hair care following the perming process, but they are not direct consequences of simply using too much hair per rod.