Performing a patch test is essential to identify any potential allergies, even if your client has used coloring products before. To conduct the test, simply mix the Liquid Dye with Oxydant, then apply a small amount behind the ear. After 10 minutes, rinse the area thoroughly.
If there are any signs of itching, redness, burning, or other allergic reactions during or after the test, it's important to avoid proceeding with the treatment. In the event of an allergic reaction, advise your client to seek medical attention immediately.