I've been double processing and colouring my natural medium brown hair for over 40 years, in order to achieve the lightest shade of blonde that I can. I've also been using Clairol Shimmer Lights Shampoo for the majority of those years. The biggest issue I've had after colouring my hair is that it would always turn out to have such an overall brassiness and bright yellow hue to it. This all changed for me on the day that I was fortunate enough to discover that if I use Clairol Shimmer Lights Shampoo a minimum of 2 or 3 times after colouring my hair, the results are amazing. I've been told often by my stylist that I have coloring my own hair down to a science. Not to pat myself on the back, but I fully agree,lol!