ALWAYS READ THE SAFETY INSTRUCTIONS AND FOLLOW THE METHOD OF USE. PRELIMINARY SENSITIVITY TEST: 1) Allergies can arise unexpectedly. Therefore, it is necessary to carry out a preliminary skin sensitivity test 48 hours before each application, even for customers who have already used colouring products before. The preliminary test must be carried out through a test that reveals the allergy with the following procedure: Apply a small amount of product with a swab or cotton swab on an area of 1 cm2 of clean skin in the hollow of the forearm. Leave for 45 minutes without covering or touching, then rinse with warm water, dry gently and inform the client to leave for 48 hours without covering or touching. If rashes, redness, swelling, burning, itching or other similar symptoms appear, the product should not be applied and the client should consult a doctor before re-colouring her hair. If these symptoms appear within the initial 45 minutes of application, rinse immediately. The absence of a reaction to this test does not guarantee to avoid allergic reactions in a future colour. However, this test is an important precaution. Consult a physician if in any doubt.