3M Marine Adhesive Sealant 5200 - Permanent Bonding and Sealing for Boats and Marine Applications - Black - 3 Ounces

Best adhesive I know of for sealing and bonding at same time. Cures hard and resilient. It is my go-to if I want it waterproof and securely bonded. If you might have to remove it later without cutting, use 3M 4000. I always get this size, small size tube is way overpriced. It is gooey and gets on every thing so wear gloves and keep mineral spirits solvent handy to remove any smears.

holy crap this stuff is sticky and it will get everywhere if your not careful but it will definitely put a water tight seal on anything you use it on. I used it to seal some speakers in motorcycle saddlebags I have no worries that they will leak

This stuff takes forever to dry but once it does, it is great; hard and robust and able to take a lot of abuse. I use it to repair mountain bike shoe soles and moto dirt bike soles (that are gouged because of the pegs).

Bought for some kayak installs and it works great.

Would’ve gave five stars but it did not come with the tip.👎

GOOD STUFF

3M Marine 5200 is very much a marine industry standard -- for a reason. It does what it does very well, but don't order this unless you know exactly what that is. It's a "sealant" that takes a full 48 hours to cure... and once it does cure, congratulations, whatever you used it on better be something you want to stay put forever-ish.It's also a "use it or lose it" $20 tube. Open it -- and consider anything you leave in the tube as toast. You're not just going to stick a nail in the tip like it's RTV and use it later. It's also fussy about how you prep the mating surfaces. Acetone? Perfect. Alcohol? Congrats, it will never set. Never. READ THE LABEL.

Most importantly this stuff will not cure even after 2 weeks! I don't know why it's is so finicky but apparently the consensus is it most likely will jot cure for you either.I purchased this because some users online said it was the best permanent bond for rubber/neoprene muck style boots and waders. However, like other purchasers, this stuff generally will NOT cure. I googled it and read that just like many urethane adhesives it needs moisture for curing. I am now trying to add water to it and and set a damp paper towel over it to aid moisture curing and my first attemp a few hours later the water seems to have liquified it more. I did have a small portion cure but the majority of it has not. I tried squeezing out a glob like you do with epoxies and then stirred water into it and applied it to some rubber. The left over mixed with water spot has not cured after a few hours. Don't get it on anything you don't want it on because it's quite greasy like and is difficult to remove. It gets into small crevices and threads but does seem to be out with lots of scrubbing but generally leaves a stain.I am wondering if windshield adhesive would just be a better product for bonding and sealing.