Kool-Aid has long been used as a way to dye and add color to hair. However, when it comes to dark hair, not all colors are suitable. The best colors of Kool-Aid to dye dark hair are red, purple, and blue, depending on the desired effect. Blue Kool-Aid will dye the hair a darker shade of blue, while red Kool-Aid will give a reddish-purple hue. Finally, purple Kool-Aid will give a dark, deep purple color. When using Kool-Aid to dye hair, it's important to follow the instructions carefully and to ensure that the hair is properly conditioned afterwards.