Sealing okoume end grain

Probably overthinking here, but I'm wondering how important it is to completely seal okoume with epoxy against water intrustion.  

I'm building the Lake Union Swift and I'm ready to start wiring the frames to the planks.  But I'm wondering if I should first seal the endgrain of the frames.  Eventually these frame/plank joints will have fillets, and those should keep any water from getting to the absorbent end grain.  But I'm concerned that if I leave a pin hole, or if one of the fillets somehow cracks and I don't detect it immediately, that water could get in.

Is it generally a good idea to seal up this endgrain on frames/bulkheads before they get installed?  And if I do, is it best to leave the sides of the frames uncoated so that the eventual fillets can more fully bond with the raw wood?

Thanks for any insights,


6 replies:

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RE: Sealing okoume end grain

   Even though I'm a belt and suspenders kind of guy, I'd say it is overkill.  You're creating quite a bit of extra work, having to make sure you don't accidently fill a stitch hole, wanting to make sure the epoxy is still in the green stage (less than a few days old) to get a good bond with fillets, having to make sure you don't creat bumps/lumps that might impact fit-up, increasing the likelihood of different levels of final "color" of the wood on the finish, etc..  All these potential negatives, and I've not heard of any reasonably careful buildiers complaining on the forum about water intrusion in this area due to bad filets.  - which then get more coats of epoxy and varnish or paint even after being filet.  Seems the "per manual" assumbly instructions - no need to seal frames prior to assembly - are more than good enough for this concern.  

And end grain absorption would be only very slightly of any more concern than water getting to the side of a panel.  Water touching the wood anywhere would be almost equally bad.

With that said, you instincts are good.  During your build if you note an area that might be problematic, like: "Will I be able to get a good coat of epoxy up under the breasthook, or inside this area that will be enclosed?" and have your doubts, consider doing some pre-coating.

RE: Sealing okoume end grain


Thanks Bubblehead--that's what I was hoping to hear.  I was asking in part because the Tenderly manual recommends pre-coating the frames on that boat, which is similar to the Lake Union Swift.  (The latter, being a Pro Kit, doesn't have detailed instructions.)

But on the Tenderly, the frames (or at least some of them) are out in the open, whereas on the Swift, they're completely enclosed by the bench seats.  Thus I was wondering if the recommendation for precoating the Tenderly frames might be for getting a better finished surface.  E.g., making it easier to sand the raised grain.

I don't terribly mind the extra work involved, but the other downsides you mention were on my mind, so if there's not much concern about water  intrusion, I'll skip the precoating and instead apply the epoxy after the structures are installed.

Thanks for your help!

RE: Sealing okoume end grain

Hi Jack, 

fwiw, i use a filletting approach that addresses this type of issue without a lot of extra work and simultaneously improves the bond of the fillet.

as part of my fillet process, i first go over the area to be filleted first with a coat of plain epoxy applied with a foam brush....and i am usually, at that time, pretty diligent to ensure the end-grain is getting epoxy coated.....just push the foam brush with the epoxy hard into the joint/watch it come out the other side.

i then move right into filleting depending on the piece and mixing times and how much epoxy is involved....there is typically no more than a 60 minute gap between the plain epoxy coat and then the fillet.

the advantage of this approach is that if your fillet is a bit firm, it will still have a great bond to the underlying wood becuase it locks into the plain epoxy that penetrates deeper into the wood structure....and it further minimized the liklihood of a void or gap...

anyway, i thought i would pass that along.   




RE: Sealing okoume end grain

  Thanks H.  That absolutely sounds like a worthwhile step and I will follow it.  I appreciate you passing that tip along.

RE: Sealing okoume end grain

I'm with H on this as well; it's easy enough and not really uneconomical in the overall scheme of stitch'n'glue to precoat surfaces with neat epoxy before applying reinforcing fillets. Just give the unthickened stuff a while to get tacky before filleting blend is placed, otherwise it'll tend to slide around too much for efficient placement / shaping.

You want to do a really neat job of it too you can masking tape off those surfaces beyond where your fillets will end up. Takes time and patience but I found much less than that spent cleaning off hardened epoxy that ended up where it wasn't really needed or wanted when assembled my Waterlust a couple of years ago.  

RE: Sealing okoume end grain

just to build on spclarks point....below is a picture of masking in anticipation of filleting on a kayak build.  as sp says, makes a big difference in terms of neatness.

 the blue tape goes on, i then paint with a bit of unthickened epoxy, then i come in and do the fillets.  the one thing to remember, pull the tape off after you have stopped diddling with it and before it is cured....and then don't mess with it :)

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