To use Crazy Color Marshmallow hair dye, first do a strand and sensitivity test. Then, shampoo your hair with a pH - neutral shampoo without using conditioner, and towel - dry it. While your hair is still damp, put on gloves and apply the dye evenly. Leave it on for 15 - 30 minutes, then rinse thoroughly until the water runs clear. Remember to avoid dandruff or harsh shampoos as they can quickly strip the color. Use a sulfate - free or color - friendly shampoo and wash your hair as little as possible. After shampooing, rinse with cold water to seal in the color. Also, stay out of too much direct sunlight and avoid swimming in chlorinated water as they can fade the color. And always do a patch test before continued use. If you experience redness or itching, stop using the product.