What procedure is typically performed to check for allergies before applying hair color?

The procedure that is typically performed to check for allergies before applying hair color is the patch test. This test involves applying a small amount of the hair color formulation on a discreet area of the skin, generally behind the ear or on the inner elbow, to observe for any allergic reactions such as redness, itching, or swelling. Conducting a patch test is crucial because it helps identify any sensitivities or allergies the client may have to specific ingredients in the product, ensuring their safety and comfort before proceeding with the color application.

A strand test, while important for assessing how the hair will react to the color, focuses more on the hair's condition and the final outcome on strands rather than allergy concerns. Similarly, a color test is a general term that may refer to evaluating color results but does not specifically relate to allergy testing. The foil test is primarily used to isolate sections of hair during highlighting processes, rather than for allergy assessment. Thus, the patch test stands out as the essential step for allergy screening before hair color applications.