Enamel Product.
Grimy grey colored effect ideally suited for creating streaks of dirt over sand and light colored surfaces. Also suitable for other effects such as add chromatic richness to any piece or surface. Shake well before use. Apply your streak with a fine pointed brush in irregular vertical lines from upper parts on sides and let the paint dry for about 10 minutes. Next take a flat brush moisted in White Spirit and swipe with little pressure over the earlier applied streak to soften the effect and create a natural look.