We feel confident in saying that taking your hair to a brighter, blonder hue requires the most upkeep of all shades. This is because lifting your hair's base color with bleach requires more processing and chemicals than dyeing it a darker shade. Doing so also leaves the hair more prone to breakage by opening the cuticle, which then allows for UV rays, pollution, and other elements to enter (and moisture the exit), thus making the color appear duller and brassier (read: yellow).
But even if you think you've hit the point of no return with your blonde's level of brassiness, know that there are some great purple shampoos that help restore your once-flaxen vibrancy (or prevent yellow-tinged hair from happening in the first place). Why purple? Think of it as a color-corrector: purple tones will cancel out yellow tones. "Over the weeks, after the color and toner fade on your carefully executed blonde, that yellowy, brassy tone makes an unwanted appearance," explains AJ Blackadder, a Redken color ambassador.
"So grab a purple shampoo, and watch it work its magic."
Celebrity colorist Justin Anderson calls this shampoo "the best violet pigmented shampoo on the market." It's also a favorite of Kristen Cavallari's, and all for good reason. It's sulfate-free with a deep violet pigment to protect your hair color while deep-cleaning your strands.