Q: What is the difference between a normal perm and a piggyback perm? And what does it look like?
In a standard perm the hair is wrapped around perm rods so that the hair layers over itself until you have wound the entire segment of hair on the rod. This is called a croquignole wrap. It is perfect for many lengths of hair and the size of the rod is usually determined by the level of curl desired and the length of the hair.
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 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