Sikaflex 291

[Yarrow]

Sikaflex recommend using primer 290DC for deck caulking with 291sealant. I have some deck seams, on new wood, coated with varnish. Can I get away with this, or do I need to clean it all out and use 290DC, which is described as "film-forming" (another word for varnish?)

 

[Peterduck]

I understand that the Sikaflex primer is an epoxy resin, so it would not be in the same class of beast as varnish. I suppose that it depends on how big the job is, and how much you are prepared to risk having the Sikaflex fail because the underlying varnish's grip on the wood has failed.
Peter.

 

[Seagreen]

Echoing peterduck here. My instinct is to clean back to bare wood. The varnish will fail within 2 or 3 seasons then you'll be "drip city" down below.

 

[Yarrow]

Thank you. What would be the effect of using the Sikaflex direct on to clean wood?

 

[Seagreen]

On clean dry wood, it sticks very well. My vessel is caulked, then actually sealed with sikaflex! ( I didn't do this, though) It doesn't leak much through the planking, though the garboards can weep a bit.

 

[benjenbav]

It sticks pretty well to hands too!

 

[pyrojames]

I use it for bedding on clean wood as a compressible gasket, but always prime (normally with epoxy) when I actually want a good seal. So for decks..... /forums/images/graemlins/smile.gif

 

[ErikBenson]

I read that they don't recommend 291 for deck seams . . .what's that about? I got some builders Sikaflex Pro 11FC it seems the job but can't get anyone to tell me the differencs ?
I will use a type of wood prep before -water based epoxy -1010. I was also told never to put epoxy near polyurethane. . .all getting confusing.
291LOT for gumming down deck boards but not for seams ? or what?