Which service might require a sensitivity test?

A sensitivity test is often recommended prior to certain hair services to determine if a client has any allergic reactions to the chemicals that will be used during the process. In the context of permanent waving, this is particularly important because the chemicals involved can cause skin irritation or allergic reactions in some individuals. Implementing a sensitivity test before permanent waving helps ensure the health and safety of the client, allowing the barber to assess how the client's skin reacts to the products.

In contrast, services such as clipping, shaving, and basic styling typically do not involve chemicals that would require a sensitivity test. While it is always important to consider individual client sensitivities, especially regarding skin irritation, the chemical processes used in permanent waving stand out as the type of service where a sensitivity test is explicitly necessary.