Pirates of the silicon rubber adhesive sealant

[jleblanc31]

Is there a difference in the marine silicon and silicon I get from the home depot or auto zone? I know there are heat sensitive silicon for valve covers water pumps and rear end covers, oxygen sensor safe silicon for engines I've also seen silicon that said not to be used under water. Is general purpose silicon good enough with boats or do I need to buy stocks in 3M . I'm getting ready to reseal my chain plates wood slide top pieces and other knickknack spots to get my mac water tight and I want it to last more than a month.

 

[John]

Oh yes.........

There sure is a difference. Try the "depot" stuff and u will find out. Good luck to you for not researching on the internet. Tons of info u know.

 

[Maine Sail]

If..

If you want it to last in an exterior marine application avoid silicone except for parts that require its use such as ports, hatches and Beckson products.. Silicone does not adhere very well to metals but does get into pores of wood & gelcoat making future fiberglass repairs, varnishing or re-painting next to impossible or at the least very difficult.

Not only does silicone not adhere well to many surfaces, especially ones that can flex and move slightly, for sealing out water, but nothing wants to stick to where silicone was or had been in the future. The removal of silicone contamination can be done but requires lots of work and sanding. Polyurethanes or Polysulfides such as 3M 101, 3M 4200, 3M 4000 UV or Sikaflex 295, or marine suitable butyl tape, are all far better choices for re-bedding deck hard ware than silicone, especially chain plates that move and flex. DO NOT USE 3M 5200 !!!!

 

[Brian M H23]

5200

I got 2 tubes of 5200 in prep for hull-deck joint work..is this a bad idea?

 

[Ross]

Is there a marine equivilant to butyl rubber caulk?

That stuff stays sticky and is self healing in rain gutter repairs. Remember, If the caulk says that it is good for 50 percent joint movement and the joint is only 1/16 inch thick that doesn't allow for much wiggle room. I think that I would like to see a nice deep groove milled into the top of the casting so that a thick gasket could be formed with the caulk.

 

[higgs]

Another point of view on siliconje

According to Practical Sailor there is no difference between "marine" and regular silicone. They did research on this a number of years ago and found that only 2 or 3 different companies manufacture all the silicone. There is no West Marine Silicone factory. PS did say marine distributers claimed they add a non yellowing agent. I have used both and have not been able to tell a difference.I think that the "marine environment" label can often be a bit of hype. I look at my house's environment - or my car's and find it to be a lot harsher than my boat's. My boat sits under a tarp all winter, while my house and car have to deal with the melting/freezing. Both operate year after year in temperature swings that can exceed 100 degrees.

 

[Deadline]

My two cents

I prefer LifeSeal marine caulk. And I only use clear because white or black exagerates any errors. Stuff works best in the caulk gun, with plenty of acetone and paper towels on hand to clean as you go.