Final answer:
The angle at which a permanent wave rod is positioned on the head during a perm is known as the wrapping angle. This angle is important for achieving the desired look in a permanent hairstyle, which uses chemicals to set the hair in curls or a straightened state for several months.
Step-by-step explanation:
The angle at which a permanent wave rod is positioned on the head is commonly referred to as the wrapping angle. When hairstylists perform a perm, or permanent hairstyle, they wrap the hair around rods before applying a chemical solution. The position of these rods is crucial as it determines the direction and the tightness of the resulting curl. Proper rod placement and the wrapping angle are significant for achieving the desired permanent hairstyle.
Perms can be either thermal or chemical. In the chemical process, chemicals are applied to the hair, which is then wrapped around forms to produce the desired hairstyle. This technique can also be used for chemical straightening or relaxing. In this scenario, the hair is flattened instead of curled during the chemical reaction. The hairstyling result, whether curly or straight, is intended to last for several months, which is why it's deemed a permanent treatment.
Temporary waves are achieved differently. When hair gets wet, water molecules penetrate the keratin strands and disrupt hydrogen bonds that help keep the hair's structure. As the hair dries and new hydrogen bonds form, the hair can maintain the new, temporarily curled shape that was set by styling tools and techniques.