Because the red pigment molecule is very small, red colours are notorious for fading fast. In fact, this was the very reason why I created Deep Red, simply because people were using permanent red colours to replenish, and the hair was becoming more and more damaged. When you notice Deep Red is fading fast it is typically due to the hair being porous and probably heavily lightened. Such hair types have an open cuticle that allow the red colour molecule to be flushed very readily from the hair. Therefore, you must keep using Deep Red as a two-minute conditioner proceeding every other shampoo. Eventually, a saturation point will be reached, whereby the hair will become so full of the red, fading starts to slow-off. As a product, Colour Restore Deep Red goes a long way. You only need to use a small amount with each application. Therefore, just keep using the product. Ultimately, it is a conditioner, and will not harm the hair, and at a certain point you will notice the red begins to retain, due to the hair becoming filled. From this point, you won’t find it necessary to use Deep Red as frequently.