Black Rub is a technique where you toothbrush black acrylic paint onto a resin toy, then use a damp paper towel to clean it off. Black paint stays in the deep areas showing off the details of your resin toy. Black Rub gives the toy an old fashioned look, like an old antique toy whose paint is worn off in places. Be sure to wear latex or vinyl gloves to keep your hands from getting messy. All this information and more is found in my book, How To Make Resin Toys by J.E.Moores.