Color correcting conditioners work two ways: For darker hair they contain a red or brown dye that will provide a little staining effect. For blonde shades they contain a purple dye known as D&C Violet # 2. The purple dye cancels out some of the brassiness and supposedly brightens blond hair.
The problem with this approach is that it’s very difficult to deposit very much dye from a rinse out system. When we’ve evaluated these products we haven’t seen much of an effect but they do work to some extent