Glue

Gorilla? Tom

Sounds similar to problems related to boatbuilding. There, the choice #1 is epoxy, #2 polyurethane. Both messy, epoxy can induce alergy-wear latex gloves. Good luck

Sounds similar to problems related to boatbuilding. There, the choice #1 is epoxy, #2 polyurethane. Both messy, epoxy can induce alergy-wear latex gloves. Good luck

Yes, they would be good choices. I've used epoxy outside and I've used Titebond III with excellent results so far, but it has only been a year. Titebond II I've had outside for about 5 years now with no problem. I've yet to try a urethane yet though.

| I have a project and need some advice. I have a medium size sign I | need to build for a local church. The design plans call for 6x6 | posts and an arched top. Doing the bending of the facia boards on | the top is not a problem. But I plan on making the 6x6, and the | facia, from a glued up lamination. The wood of choice is mahogany. | Now for the question, "What is the absolute best glue to use?" | Bear in mind this is going to be outside in the wonderful humid and | hot Alabama weather.

My experience is limited; but I've had good results in Iowa with both Epoxy and TBIII. I'm fairly confident that the epoxy will hold up - but I'll have to let you know about the TB in another 20 years or so...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

I agree with others, Epoxy or Gorilla. That being said, I think most glues will work if there is good preparation and the finish is done well and maintained. I made a sign 10"x26" from old fir scraps, glued with good old TB2. The sign is used in the local mountains. The sign is painted and has lasted over 10 years!

Dave

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PolyUrethane glue is an excellent exterior, waterproof glue, but will not fill gaps. If the joint is loose do not use it.

Epoxy will fill gaps and voids, but will have an easier to see glue line because of it.

Depends on your joinery, I guess. I like not having to mix, so tend to favor polyurethane.

Harvey

I have tried Gorilla glue and have not been impressed with it - had it fail too often. Also tried "Probond?" and it was worse.

Sounds like it will be epoxy. Now for the $64,000 question, "Which Epoxy?"

Thanks again

Deb

Epoxy thickened with micro-balloons to the consistancy of mayo.

Anything else is a wannabe glue by comparison.

Lew

You should. I used to use Gorilla, now I use Elmer's polyurethane glue. Good stuff. In another reply in this thread someone said that polyuethane doesn't fill gaps. Not sure where that came from. The polyurethane foams up and most certainly will fill gaps. I know that there are different formulations, some billed as low foaming, but unless the gaps are ridiculously large it will fill them.

Some reviews:

This begs some questions. I've used both and never had either one fail, whether indoors or out. What exactly failed, and how?

Frankly, any. The epoxy is so much stronger than the wood it doesn't matter. If you're looking for a brand recommendation, West Systems Epoxy by the Gougeon Bros. is the gold standard. They literally wrote the book on epoxy starting with their work on ice boats. They have a very extensive web site with a tremendous amount of information.

Yah, the foam fills the space, but it doesn't provide strength. "Gap filling" is a glue-boffin term for "fills the gaps and supplies strength." The microballoon fans here can give you the details.

Right, the foam fills the gaps but with no strength, so doesn't count. You have to have tight joints for the glue to hold properly.

Harvey

I do take your point about needing to clarify that the properties of a gap filling polyurethane doesn't equate with the full strength of a tight fitting joint with the same glue, much less epoxy, but the polyurethane will certainly add more strength to a slightly loose joint due to its foaming properties. Saying it doesn't provide strength is as much of an oversimplification as the original comment that it doesn't fill gaps.

I'm fairly fluent in epoxy, been working with it for twenty-five years knocking around in boat yards, etc. Microballoons are the lowest strength filler, but provide all the strength you'd need for woodworking and cabinetry work.

You can use waterproof woodworker's glue. Make sure it says "waterproof" or "water resistant" on the package. Elmers or Titebond are two good brands. Use stainless steel fasteners to prevent staining. My concern would be protecting the mahogany from the elements--maybe a marine epoxy varnish.

Since everybody else has recommended PolyUrethane and Epoxy I will give you a third alternative: Resorcinol. Resorcinol has a red glue-line, but that will not show with your Mahogany. This is the stuff typically used here in NZ to manufacture laminated beams etc - it's boiling-water proof...

I made some outside stairs to our verandah by laminating 6x2 into 12x2 with Resorcinol near 10 years ago and they're as good as the day I made them. Untreated, non-painted eucalypt.

-P.

SFWIW, resorcinal is the weapon of choice when gluing white oak.

Epoxy is not a good choice for white oak.

Lew

Yes, Resorcinol! I had forgotten - not used it for years. Used to be the glue of choice for exterior joinery. Simpler to make up than epoxy - what is it, powder into liquid or the other way around? I forget.

Seems like it could be a bit harder to find though, right? I mean I don't recall seeing it at HD.

And, uh, not to ruffle feathers, but also not gap filling. Joints should be well fit. I suppose you could say it would add strength across a gap,(like polyurethane, too) but only like caramelized sugar adds strength to flan.

Harvey