The more you wash your hair, the more you have to use a toner to define the hair color. When you apply a blue semi-permanent dye, color … Deep condition your hair. A color remover takes away the added color pigments, leaving you with your natural hair color. Use a deep-cleansing shampoo to help clean your hair from any hair buildup or leftover dye. The more concentrated the tone is, the darker the blue color is that will result from its use. https://sugarandfluff.com/best-blue-black-hair-dye-for-dark-hair There are three main hair toner products: purple and silver shampoo, hair dye, and ammonia toners. If you have any leftover dye in your hair, use a color remover. Once you have toned your hair, protect it from the sun to prevent fading of color. When you dye your hair blue with a semi-permanent dye, what you are actually doing is adding a certain amount of blue tone. Limit the usage of styling products on bleached and toned hair. It helps moisturize and nourish your hair.