Under a microscope, a strand of hair looks not unlike a snake. Its outer covering, the cuticle, is made up of semicircular keratin "scales"; the smoother these lie, the more lightreflective your whole head will be. Ironically, both heat styling and hair color—yes, the damage duo—can amp up shine.
"Heat from a blow-dryer, curling iron, or straightener is like ironing a shirt," says Marco Santini, co-owner of NYC's Ion Studio. "It smooths out all the bumps." (For the best cuticle smoothing angle, hold the dryer above your head, pointed toward the floor.)
And dye itself is reflective; to make clients such as Kate Beckinsale extra sheeny, colorist Tracey Cunningham follows every dye job with a glaze that keeps color "fresh and shiny for weeks." To maintain glossiness at home, steal a salon trick: Comb through a hydrating hair mask, then wrap hair in a hot towel (60 seconds in the microwave will do it). Leave the towel on long enough for hair to cool down, allowing the cuticle to close and lock in moisture. Ideally, light penetrates the complexion's top layers, is diffused laterally, and reflects back out.
Redken Color Extend Shine Enrich maintains luster with cranberry oil; "for a little bit of shine at the very end of the blow-out," Santini sprays two or three pumps of Davines Defining Gloss into his palm and works it through dry hair.
