Diving Duck, the 3m 4200 sticks well as long as the surface is not oily, it’s a marine sealant, they also make a 5200 that also never hardens but needs to be sanded or scraped away to remove and it is said should not be used by a novice unless they have a note from their mother, the 4200 is a little more forgiving. The down side is its not cheap nor is 5200 and once opened must used in 24 hrs or the rest of the tube becomes unusable. If you decide to use it get the fast set up one even that one takes a day or so to set up and they also come in black as well as white but black is a little harder to locate.