How do people carry out a skin test for hairdressing?

Skin tests in hairdressing are used to check that a client is not allergic or sensitive to the ingredients in a colouring product prior to treatment. A mixture of the colour with hydrogen peroxide is dabbed onto the clients inner elbow or behind the ear 24 - 48 hours prior to the colouring treatment. If the skin shows signs of redness, itching or swelling then the treatment should not be undertaken.