Oklahoma Cosmetology Board Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

Before performing any chemical service on a client's hair, conducting a patch test is crucial. This step helps to determine if the client has any allergic reactions to the chemicals that will be used. The patch test typically involves applying a small amount of the chemical formula to a discreet area of the client’s skin, such as behind the ear or on the inner arm, and observing for any signs of irritation or allergic response over a 24-48 hour period. This precautionary measure is vital to ensure the safety and comfort of the client during the chemical service.

While applying a leave-in conditioner, shampooing the hair, or using a styling product may play roles in different parts of the hair treatment process, they do not address the critical aspect of assessing the client’s sensitivity to the chemicals involved. Without conducting a patch test, a stylist could unknowingly put the client at risk for an adverse reaction, making it an essential step that must not be overlooked.