When thinking about removing old colour it is vital to understand the chemistry of the colour you’re dealing with before deciding on a course of action. Then consider doing some strand tests to check for effectiveness before carrying out the proposed service on your client.
Direct dye colour molecules are large and sit on the outside of the cuticle layer. However, if the cuticle layer is damaged, some products are more prone to staining the cuticle and then it’s very difficult to completely remove them.
Clear (!) tint is sometimes called a clear gloss or a clear glaze by some manufacturers. It's an oxidising tint that releases ammonia when mixed with developer (as they all do) and the ammonia lifts out the direct dye colour molecules, providing they haven’t already stained the cuticle layer.
Bleach tends to have the opposite effect to the one intended and usually causes direct dye molecules to stain the cuticle layer to an extent so for example, if you bleach a bright purple direct dye, most of the purple is removed but then you’re left with a green hue on the hair that you still need to cover. That’s fine if the client doesn’t want anything lighter than a cool level 7 or above.
