My boat has been in the water about two months. I wash it at least once/ week with Kit car wash/wax. The black streaks are still coming off completely with each wash. By now with wax, they would remain after a wash. I applied a 2nd coat of Pro-Polish to the flybridge today. I usually re-wax the topsides at about this point in the summer. This is the first time I haven't had to work any black streaks out. I give this stuff an A+. Just bought some more at Boatfix.