Using this Electric Watermelon semi - permanent hair dye is easy. First, lighten your hair to the lightest level 10 blonde. Then, do a strand test to see if the color looks good on your hair base. After that, you're ready to apply the dye. Depending on your hair length and thickness, use the recommended number of 4oz containers: 1 for short hair, 2 - 3 for medium - length hair, and 3 or more for long hair. After application, follow the included instructions for best results. The color will last 4 - 6 weeks. Before using it regularly, always do a patch test on a small area of your skin. If you notice any redness or itching, don't use the product. To make the color last longer, keep the tub resealed when not in use. And enjoy your bright neon pink hair!