To use this Intensive Oxidant Cream Developer, first mix it with the Intensive tint at a 1:1 ratio. For those with sensitive skin, go for the 3% 10 volume formulation, which is also great for lashes. If you want to cover gray hair, choose the 6% 20 volume one. Before applying, do a patch test on a small area of skin to check for any allergic reactions. When the product is unopened, it can last for 12 months. Once opened, use it within 6 months. Keep it in a cool, dry place away from direct sunlight. After use, make sure to close the container tightly to maintain its quality.