What should be the first step in a chemical service on hair?

The first step in a chemical service on hair should be to conduct a patch test. This is an essential safety procedure that helps to determine whether the client has any allergic reactions to the chemical products that will be used during the service. A patch test typically involves applying a small amount of the chemical solution to a discreet area of the skin, usually behind the ear or on the inner elbow, and waiting for a specified period (typically 24-48 hours) to observe any adverse reactions, such as redness, irritation, or swelling. By performing a patch test, cosmetologists ensure the safety and well-being of their clients, mitigating the risk of serious allergic reactions during the actual chemical service.

Other options, while they may be part of the overall chemical service, should not be the initial step. Applying the chemical solution without testing for allergies first can lead to unexpected and potentially harmful outcomes. Shampooing the hair is often done to prepare the hair for treatment but is not the first action taken. Sectioning the hair is a preparatory step for application and styling but also follows safety procedures like patch testing.