Ardell Gray magic color additive, it helps you cover gray hair completely. It works on even the most resistant gray hair. Compatible with all color tints, toners, and no peroxide hair colors. 10 drops for every ounce of color. It added to your color is all you need to cover the most resistant gray hair. Decrease fading and increase coverage. Helps color penetrate deeper into the hair shaft for longer lasting color. Adds intensity to any hair color. It can be used with any hair color, additive, toner, tints, and non peroxide hair color. Will not affect processing time.