3M 5200 Clean Up
Mineral spirits and tons of paper towels will clean 5200 that has not cured. However, I don''t think that 5200 will adhere to starboard well enough to provide a seal. From my experience with starboard nothing will stick to it except special glues formulated for that purpose, not something you''d want to use on a rubrail. When using 5200 keep in mind that it is very sneaky, has eyes and froglegs and will jump all over you and your boat and has been known to even jump onto and infect unfortunate passersby who happen to strolling the dock admiring your fine work. Keep a lot of paper towels handy, copious amounts of spirits available and check the bottoms of your shoes often.