Gluing Ipe Wood for Outdoor Exposures

Ipe's oily nature is not conducive to strong glue joints, especially when movement stress occurs. Here are some reports of success and failure at gluing Ipe in outdoor situations. December 26, 2007

I have had more glue-up failures with ipe. I'm using PUR on table rails using biscuits. I will have to change design to use M&T's with pins to hold. The furniture is used outdoors. Is there any glue product that will hold this stuff?

Forum Responses
(Adhesive Forum)
From contributor V:
Most people cannot glue ipe successfully, long-term. Those that do seem to do so successfully, I suspect are gluing a different species. Ipe is a group of species, and some species appear to glue more successfully. How to tell one from the others? I don't know. We simply do not glue it, or if we do, it is reinforced with 100% other secure methods.

From contributor S:
I glue up ipe all the time. The trick is to have freshly milled or sanded surfaces. I use Gorilla Glue and I dampen both sides. This works for most oily woods up to vera. It's not perfect, but it works pretty well.

From the original questioner:
Yes, I have followed those guidelines. The problem is, the glue seems to hold well for about 6 months or so, but then failures occur. I make outdoor furniture, chairs, tables, etc. and the fact that it is outdoors in the sun, etc. causes the failures. I have changed my table design to now use solid legs (was laminating them up to 2 1/2" thick) and M&T joinery, pinned.

Also, I find it difficult to have fresh milled M&T joints, since it takes a lot of time to mill the joints, usually about a full day for 38 or so. And for the arm joints, I have to wait until the seat slats are installed before I can make them up, and that can be another day or so. I have several items displayed at various businesses around town, all inside, and so far no failures have occurred there. The problem is items used outside in the weather.

I have come to the belief that this stuff cannot be glued using anything available to us semi-pros - one must use joinery and mechanical fasteners. The Adirondack chairs I make do not have any glued joints, just ss screws and stove bolts. So no failures there.

From contributor V:
Building with whole boards and M&T joints pinned is a good strategy. That is what was done 200 years ago. Craftsmanship is what made it work.

Semi-pro or pro, the wood doesn't care, and seems to reject glue. I know of a huge public garden project that failed in the first 6 months and put a shop out of business. Now the ipe has screws and nails and all sorts of stuff so the posts and brackets don't fall onto visitor's heads. A real mess. All related to failure gluing ipe.

From contributor S:
Outdoors does make a challenge. But I think I have the solution for you - a glue with more flex. Try the e6000. This is a silicone-based glue, so it has some flex and sticks very well. It makes a permanent bond between wood and metal where the wood breaks before the joint. So this should take care of the movement. And of course pinning the joints will help too. The glue takes a few days to fully cure if it can't get much air. It also keeps a long time in the tube.

From the original questioner:
Where would one get this E6000 glue? I might try it out.

From Jeff Pitcher, forum technical advisor:
E-6000 is not the answer. It may glue up okay initially, but you will be repairing your work eventually. You've got to glue ipe when it's freshly machined. It is very important that your blades are sharp, as ipe is easily burnished. If burnished, nothing you try will work. Go with a good cross-linking PVA or a liquid PUR and you'll be fine. On the other hand, M&T joints sound like the best alternative!

From contributor S:
I have glued up thousands of hand planes with ipe soles. Gorilla Glue is the best poly that you can buy over the shelf for oily woods I have found. But for an outside joint, I don't know. I think the e6000 is a very strong glue and it has not failed me yet. It is not a bad price and you can get it at most hardware stores. Goop is the same thing, but with the e6000 you can get a thinner one that flows.

There is a way to test the joints fast. Glue some tests up, let them cure fully, then alternate dunking them in water, freezing them, and getting them around 100 degrees over and over. That will give you a good idea of the cycles the joint can handle.

I did a bunch of testing years ago and found to freshly mill/sand both sides, dampen both sides, and Gorilla Glue worked the best for oily wood. But I found the e6000 made a stronger joint. So far I've not had a joint fail with it, but I use it more for wood to metal and other oddball joints.

From contributor D:
We've been using ipe for about 8 or 10 years now. The key to this particular problem is the fact that the product lives outside. I have had test panels of ipe live to a ripe old age indoors with Titebond, and with Weldwood plastic resin glue. Outdoors, the only thing that has held up is epoxy. We deliberately machine the joint sloppy, to allow room for the epoxy resin. We butter both joint surfaces with fresh epoxy. Then we mix some epoxy with an additive (varies, depending on the application, usually just fine sawdust). Finally we butter the joint with this thickened epoxy and assemble the joint. We hold the joint together with light clamping pressure, or weight, or mechanical fasteners. I can't say we have a huge track record with this adhesive schedule, but we do have perhaps half a dozen projects outdoors - for as much as 7 years. No problems yet.

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
One point that contributor D mentioned is that epoxy does not like to be squeezed out, but prefers a thicker joint. Hence, light pressure is often the key that many folks miss. Note that epoxy does deteriorate when exposed to UV.

From contributor W:
I've built entry doors out of ipe. The doors were 2 1/4" thick, so I had to laminate boards. I used Gorilla Glue and they delaminated. I then used marine epoxy (I used the West System available from boat supply retailers like Boater's World). It worked great and the doors are still swinging and have not failed. They've been installed for about 3 years now. Don't use the two part epoxies from Home Depot or other homeowner stores that are for tabletops. Those are inferior. It needs to be a marine epoxy.

From contributor N:
I've had varied success with ipe. Here's what I have found:
PVA (white and yellow) is a bust.
Epoxy (West System 3) worked well on long-grain to long-grain, but show it a hint of short grain and it's a bust.
Gorilla Glue works well indoors but has failed on me outdoors.

Construction polyurethane (PL) works well outdoors. Like epoxy, it requires some body to the joint and is less than beautiful, but it has held well for me.
Cyanoacrylate worked outdoors for a small repair but is probably not viable in quantity.
For structural joints outside I used pined M&T.
In all cases except the cyanoacrylate, I roughed up the surface with 100 grit paper. I also cleaned the surfaces with acetone. For the Gorilla Glue, I wetted one surface with distilled water.

On a separate note, I own one of contributor S's planes and it has not delaminated on me. It is a great plane.