The more you wash your hair, the more you have to use a toner to define the hair color. If you have any leftover dye in your hair, use a color remover. A color remover takes away the added color pigments, leaving you with your natural hair color. When you apply a blue semi-permanent dye, color … 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 Use a deep-cleansing shampoo to help clean your hair from any hair buildup or leftover dye. Deep condition your hair. It helps moisturize and nourish your hair. Limit the usage of styling products on bleached and toned hair. 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. There are three main hair toner products: purple and silver shampoo, hair dye, and ammonia toners.