Choose a semi-permanent purple dye then dial down the vibrancy ... It works best on hair that’s pre-bleached platinum, light or medium blonde, just leave on for 30 minutes and rinse.

"It also means that blonde hair absorbs light instead of reflecting it and is more prone to damage," adds Shiel. How to use purple shampoo ... This brightens old hair dye and boosts its undertones ...

Color-depositing shampoos add specific pigments (either purple, blue or green) onto the hair shaft to maintain your desired color. Based on color theory, blondes should use purple shampoos ...