window sealants

[LeonF]

I need to re-bed the windows on my boat because of a nasty leak. They're of the 'Glued on' type with self tappers for additional support. I had intended to use Sikaflex 295 but have been advised by an old hand that the adhesive qualities might prove to be too good in the event of a breakage needing replacement, and he suggests a good silicone mastic instead- any suggestions please? An e-mail to 3M has met with no response. Also, is there a mastic that is non-toxic that i can use to re-bed the lids on my GRP built in watertanks?

L.A.R.Ferguson

 

[Guest]

Life Seal

Life Seal seems to score well here ( not Life Caulk).
It is a polyurethane/silicone hybrid which dries to a glossy finish, does not dent and seems to last better than silicone when contact with seawater is made.

 

[Guest]

I might suggest 3M's "101", as long as the portlights or windows are not surrounded by a plastic framing material.
The polysulfide will possibly melt the plastic in the frame.

Or you might consider 3M's 4200, which will allow you to remove the portlight at a later time. It is not as tenacious as
5200 which will not permit removal.

As you are "across the pond" I'm not sure if 3M's designations for their products are the same.

I am not a fan of "silicones"....as their lifespan seems to be rather short when sealing any surface that comes in
contact with salt water.

Reality is the cause of all stress.

 

[jfkal]

No alterantives

Best bet is Sikaflex 295, because it is UV resistant. Tried the 3M alterantives myself and they come off crumbling after 2 years. Yes Sika bonds well but you can always break the bond using a razor blade. Do not use Silicone, this stuff only belongs to the bath room at home and not on a boat.

 

[VMALLOWS]

Re: No alterantives

I'm not so sure about being able to break the bond witha razor blade. I started trying to remove a leaking window (put in with Sikaflex about 14 years ago) .
Realised I was going to damage either the boat or the window and gave up. A sealing fillet of sealant around the edge solved the leak, and you soon forget its there.