Epoxy or wood glue???

[Biker B.O.B.]

I'm putting a custom deck on my C12. It will be bright finished, so the joints are pretty close fitting. Since epoxy works better with a gap, should I use wood glue to secure the parts and then coat them in epoxy?

Here is a picture to help you see how tight fitting the pieces are.

[Chief Brody]

why "wood" you use wood glue and then epoxy over the top??? Why not epoxy in the joint, (which is stronger than anything out there) and then epoxy (which bonds well to itself) over it?

[Biker B.O.B.]

why "wood" you use wood glue and then epoxy over the top???

Because I've read that epoxy needs a gap. Plus, it's cleaner, easier, and less wasteful when making small batches to glue up one piece at a time. Epoxy over the top to make it water tight. The epoxy should not come in contact with the wood glue.

Also, butcher blocks are pretty strongly held together with wood glue.

[Chief Brody]

Interesting point..I would figure since epoxy will hold better than the wood itself, it would be the one to use, plus its waterproof, which I don't think wood glue is or at least as good....but I'm not a chemist!.........I'll let the Pro's answer that one....

[Steve_MA]

I just built a couple Adirondack chairs and one of my epoxy joints "popped". Bad prep...you have to wet it out and make sure you don't squeeze out all the epoxy. I looked that joint and there was only a little epoxy.

If its not an area required to hold the boat together, it might not matter much. Type 2 wood glue is pretty good stuff. There are some Wood Magazine tests/results with various outdoor glues, incl epoxy. Epoxy is the better, but type 2 and 3 wood glues are very good too. If you glued it, then covered it with epoxy....if its not a stress area - it would probably save alot of time and mess. Agreed. Assuming you have a good fit.

One of the things I have looked it epoxy fillers that arent so dark (like with wood floor). Silica works but it is said to be brittle...it comes out clear. I also tried something else - can't remember if it was cotton fiber or milled fiberglass - that was pretty clear. I would have to check my notes, but I think the 1/32" milled fiber I got was pretty clear .

If you use epoxy, just dont clamp it too hard. I would probably use epoxy on external surfaces, just precoat everything before you start. Keep the wood glue for inside.

[ks8]

ABout the *gap*... first, epoxy is gap filling better than many other glues, but that doesn't mean you *need* a gap. Why then have a gap at all? Two reasons I know of (not a professional)...

One- a gap insures that if the wood is very thirsty, there will still be plenty glue in the bond, because plenty was in there to begin with, and it wasn't all squeezed out or sucked up into a void or thirsty wood. These epoxy bonds generally have a very important structural role. Some other gluing applications are not always as vital structurally, being supported also with biscuits, dowels or other fasteners as well.

Two- in composite building and methods, floating a panel in an epoxy/filler seam surrounded by glass, ensures an even distribution of loads.

In the case of your decking, it isn't as vital to float each strip in an epoxy filler seam. If you are not using any very thirsty porous wood species, and not clamping too tightly, you might be fine without an intentionally substantial *gap*, even without adding a filler to make a *glue*, but personally, in any such application, I like the additional strength given to the epoxy binder by a suitable wood flour or similar filler, and how it acts more like a glue in application, rather than running out of the seam.

So I'd summarize by saying you probably don't need any intentional big gap for that planking or stripping, and it wouldn't be a bad idea to add a suitable colored filler (wood flour) to the epoxy so it isn't too runny, and is a little stronger. I would not use a urea based wood glue, but would stick with epoxy. Hope that helps. Keep those pictures coming....

[Biker B.O.B.]

My intent is to have no gap, since a tight fitting joint looks better when bright finished.

[cape man]

I coated all my strip joints with epoxy, applied a liberal amount of epoxy mixed with wood flour over that, and then clamped them down tight. I also painted the bottom sides of all the strips with epoxy before they got glued together, so the bottom of the deck and gunwales should be water proofed. I will then coat everything on top with epoxy and put 4 oz glass down. If that comes apart I will buy you a beer (after I drink 50 or so myself ). I think KS is right that while you can use epoxy to fill a gap and hold things together, it also is a very good glue for tight fitting joints if the surfaces are prepped properly (i.e. clean and coated with epoxy first to assure the glue doesn't just soak in). Can't see how normal wood glue is stronger than epoxy.

Wood glue is good stuff if used properly, even for boats. I made a cedar strip canoe years ago that used Elmers wood glue to hold the strips together, coated everything with epoxy, and then put glass over it all, inside and out. Thought of using wood glue on my strips, but figure the epoxy will be a stronger, longer lasting, definitely water proof glue. The forces working on this boat will be significantly different than the canoe!!!

Did use a lot of epoxy to glue it all together but what the hey...it's only money and weight...

Great job on the pattern.

[Cracker Larry]

Another vote here for epoxy

That's looking great !

[TomW]

Bob, I'm going to go across the grain here against epoxy for this project. I'm going to worry until the day I die or Cape Man's boat sinks that those strips are not going to pop off one by one due to epoxy starvation from him having to clamp them so tight. Second we all know that epoxy is very strong but newer wood working glues can be as strong and waterproof also. The one I refer to is Titebond III Ultimate. PSI joint strength is 4000 lbs not quite up there with epoxy, at 7000, but enough for what your doing. Waterproof tested for 6hrs with joint not coming apart, pretty good in my book. I guarantee the wood will break before the glue will. Not sure if it would meet the boil test.

It will also leave less of a glue line than epoxy glue with eposy and saw dust in it. They also have it in a dark color glue so you won't have any glue lines with your walnut wood.

It will also save you time, money, and keep things neater. Working time is 8 minutes, clamp time is 30 minutes, though I allow a little longer, so on those straight peices you can do those almost all of them in a day or two. Full cure is 24 hrs.

But do make sure you coat the underside with epoxy as the top side will be. I also would not be afraid to cover it with one of the fiverglasses that stay clear to protect it from the ancor and other things that go bump in the night.

I wouldn't use wood glue on many places on a boat but in this one instance I feel it is justified and you can cover top and bottom with epoxy.

Tom