Milady Cosmetology Practice Exam 2025 – All-in-One Guide to Master Your Cosmetology Certification!

The size of the curl in permanent waving is primarily determined by the size of the rod used during the procedure. The rod, or perm rod, is the tool that creates the shape of the curl by holding the hair in a specific configuration while the perm solution processes. A larger rod will create larger, looser curls or waves, while a smaller rod results in tighter curls.

The perm solution does play a role in breaking down the hair's internal structure, allowing it to take on the shape created by the rod, but it does not directly dictate the size of the curl itself. Hair length can affect the overall appearance of the curls but does not directly determine their size. Temperature can influence processing time and the effectiveness of the perm solution, but it is again not a direct factor in the curl size itself. Thus, the rod size is the key component in defining how tight or loose the curls will be in a permanent wave.