How to Chalk Dye Your Hair (with Pictures) - wikiHow
Wet your hair with a spray bottle. Take 1 to 2 inches (2.5 to 5.1 cm) of your hair and dampen it with a few spritzes of water from a spray bottle. Wetting your hair will help the chalk color absorb into your hair. If you make your hair very wet, the color will appear darker and stay on longer.