That’s where color-depositing shampoo (think purple shampoo) comes into the picture. Believe it or not, color theory is a big ...

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 ...

There's no need to lose your cool (pardon the pun), though, as that's when the best purple shampoo swoops in with its impressive hue-restoring powers. Katie makes regular trips to see her ...