Crackle Medium 8 oz. What normally takes many years of wind and weather can occur almost instantly on any painted surface with a few brush strokes of FolkArt Crackle Medium. The waterbase non-toxic medium is easy to use on furniture and decorative accessories. Different degrees of crackling - from subtle to bold - can be achieved by using either a sponge or a brush, and by varying the amount of medium applied. Change basecoat and topcoart paint colors for even more variety.