What determines the size, shape, and type of curl in permanent waving?

The size, shape, and type of curl in permanent waving are primarily influenced by the size and shape of the perm rod used, as well as the method employed to wrap the hair. When selecting a perm rod, the diameter determines the size of the curl; larger rods create bigger curls or waves, while smaller rods lead to tighter curls. The way hair is wrapped around the rod—either flat or spiral—also plays a significant role in the final appearance of the curl pattern. If the hair is wrapped tightly around the rod, it can result in bouncier and more defined curls, while looser wrapping can create softer waves.

Other factors, such as the hair's natural texture, do influence the overall outcome but are secondary to the specific characteristics of the perm rod and wrapping technique. Additionally, while the type of chemical solution and its temperature contribute to the permanency and effectiveness of the curl, they do not directly dictate the size and shape of the curl, making the method used and the tools chosen the primary determinants in the curling process.