What must be done before performing chemical services on a client?

Before performing chemical services on a client, conducting a patch test is essential as it helps ensure the client does not have an allergic reaction to the chemicals being used. This test typically involves applying a small amount of the chemical solution to a discreet area of the client’s skin, allowing time to see if there is any adverse reaction. The importance of this practice lies in the potential risks associated with chemical applications, which can cause skin irritation or allergic responses in some individuals. A patch test serves as a crucial safety measure to protect both the client and the professional.

While providing a consultation is important for understanding the client’s needs and expectations, it does not address the safety concerns associated with chemical exposure. Shampooing the client's hair can be part of the preparation for the service, but it is not a prerequisite for ensuring safety. Applying a protective barrier, such as petroleum jelly around the hairline or on the ears, can help prevent staining from the chemicals but does not substitute the need for a patch test. Thus, the patch test remains the priority before engaging in any chemical service.