Then again, something we haven't heard a ton about is purple cleanser for dark colored hair. It is available in almost any store, salon, or beauty supply. “This can be done by using detoxifying shampoos or Malibu treatments,” Miller tells TZR. Because bottle blondes tend towards warm yellow tones over time. “You may follow this with a little purple shampoo to refine the remaining tone,” Miller says. In order to have any visible color-correcting impact, your dye needs to be intense – and is usually an inky, dark dye. By using a special purple shampoo, you can neutralize those tones to ensure that your gray hair retains its vibrancy. What does purple shampoo do? If your hair is a medley of tones, some purple shampoos will do more harm than good by stripping the colours you want.