Black Jack® Plastic Roof Cement is a pliable asphalt roof cement that is ideal for many roof repairs and for stopping roof leaks around vent pipes, spouts, valleys, skylights, gutters and chimneys. Use for the construction and repair of flashings. It may also be used to seal cracks in exterior chimneys, walls, foundation joints or for lining leaking gutters and troughs. Use only on dry surfaces. Plastic Roof Cement is not paintable.