Which type of acid wave requires the application of heat?

The type of acid wave that requires the application of heat is the endothermic wave. Endothermic waves are characterized by needing an external heat source during the perming process to activate the chemical reaction that curls the hair. This heating can be achieved through a hooded dryer or other heating methods, which helps the waving lotion penetrate the hair cortex effectively and results in a more consistent curl formation.

In contrast, neutral waves do not apply heat and are processed at room temperature. Chemical waves also do not require heat as they rely on chemical reactions to break down the disulfide bonds in hair. Exothermic waves produce their own heat as a result of the chemical reaction occurring within the perm solution, eliminating the need for external heat application. Understanding these different types of waves and their requirements is crucial for successful perming outcomes.