Filling grooves and other imperfections

Not boat related, I'm building a covered deck with dimensional wood and the main beam is a LVL laminated vernier lumber. It has some grooves in it that need to be filled before I paint. Is there something in a caulk tube I could use to fill these?would have to be able to paint over. I know Dap makes some products but I'm not sure if that's the right way to go. I do have some quick fair but probably a little over kill. Thanks

Another question is i plan on using the suntuf product a poly sheet material for the roofing anybody with comments on this product?

 

Yes, you can buy adhesives for wood in sgueese bottles st the big box stores that are waterproof. Check out PL 400

 

All of the usual goo's in a tube type of products (acrylics and polyurethanes) will shrink quite a bit once fully cured, leaving a considerable depression after you've troweled it smooth. Epoxy will not. Well okay it will but at 2 - 3% of the rate of the other usual suspects.

Suntuf is a polycarbonate product and admits quite a bit of light, including UV a and B, so what ever you put down, it'll need to be covered or tolerant of this. What is the application?

 

Yes it will have to tolerate UV.The beam also has some knots in it that will need filling also.
Thanks Par,i kinda thought the caulk products would shrink,i thought about wood glue and wood flour mix,the grooves are vertical so somthing that doesnt sag.
If i use quick fair ill have to pre coat with neat if i remember correctly.Maybe just some epoxy mixed with talc and cabosil to firm it up a bit.This will all be covered with paint.