Clairol Natural Instincts and L'Oreal Excellence Creme are popular brands of hair dye to help cover up gray hair. Experts agree that any dye that comes with a deep conditioning treatment is best for covering up grays.
Keeping hair properly conditioned after dyeing is vital to the preservation of the color. Dry, over shampooed hair can be leached of its color, allowing grays to show through. In order to keep color in the follicle longer, wash the hair less. Water lets color escape from the follicle, leaving behind a duller color over time. Use dry shampoo between washes to keep the hair looking fresh and clean.