When should a barber perform a patch test?

A barber should perform a patch test before applying hair dye. This procedure is crucial because it helps determine if the client has any allergic reactions to the hair dye ingredients, particularly to chemicals such as paraphenylenediamine (PPD), which are commonly found in hair color products.

Conducting a patch test involves applying a small amount of the dye to a discreet area of the skin, often behind the ear or on the inner elbow, and then waiting 24 to 48 hours to check for any adverse reactions, such as redness, swelling, or itching. This proactive measure not only ensures the safety of the client but also helps avoid potential complications and dissatisfaction that could arise from an allergic reaction during or after the dyeing process.

The other scenarios, such as performing a test after a haircut, during consultation, or at the end of the service, do not provide an opportunity to address potential allergic reactions before the application of the dye. Timing the patch test correctly is essential for both the barber's professional responsibility and the client's wellbeing.