Q: What is the difference between a normal perm and a piggyback perm? And what does it look like?
A: The difference between the standard perm and the piggyback perm lies solely in the way the hair is wrapped for perming.
A piggyback perm wrap is used on longer hair lengths when there is simply too much hair to be wound around a single perm rod. The piggyback perm wrap uses two rods per segment of hair. Approximately half of the hair length (between the scalp and mid-point of the length) is wrapped spiral fashion around one rod using an overlapping technique, then the ends of the segment are wrapped in croquignole fashion as with a traditional perm wrap.
The finished perm looks very much like a standard perm, since the point is simply to spread a more even level of curl throughout the length of the hair. You choose to use a piggyback perm wrap not so much for a specific type of curl, but to ensure consistent amounts of curl along the length of the hair rather than having the hair grow more tightly curled at the ends and less wavy at the scalp as can happen with long hair wrapped in traditional fashion for a perm.
How to wrap a perm
Rod to roller perm
How to wrap a spiral perm