Which step is essential before starting a chemical service?

Performing a patch test is a crucial step before starting a chemical service because it helps ensure the client's safety by checking for potential allergic reactions to the chemicals being used. This test usually involves applying a small amount of the product to a discrete area of the skin, such as behind the ear or on the inner elbow, and waiting for a specified period to observe any adverse reaction. This precaution can prevent allergic responses that may lead to severe skin irritations or other health issues during or after the treatment, thereby safeguarding both the client and the barber’s professional reputation.

While the other options, such as choosing a color, discussing pricing, or walking the client through styling options, are important aspects of the client service experience, they do not directly address health and safety concerns associated with chemical services. Therefore, performing a patch test stands out as an essential measure to ensure the procedure can be conducted safely and effectively.