Thread: Polyurethane Glue Woodwork

I'm not a guru on these adhesives, but we mainly different glues if there is a specific circumstance where that type of glue is needed. That for us would typically be in laminated work where the laminated timber is wrapped with plastic in a jig or vacuum bag or similar where PVA is unable to set. From what you're looking at, Titebond is probably the big one that Im aware of that has been brought in, and at the woodshows and our professional conferences the retailers promote this as the go to general purpose wonder adhesive, but for us, at the end of the day the PVA is cheaper, its availability is everywhere and timber adhesive really cant get stronger with the exception of end grain as the timber normaly tears apart beside the join when done properly. The Titebond might be closer to cross-linked PVA, but we still use bog stock PVA.

This is from a school perspective.

When I worked for a couple of years for a business that made dining tables, coffee tables, entertainment units and such things, we used PVA almost all of the time.

If the faces being glued are a good fit, the join is stronger than the surrounding timber.

One advantage polyurethane has over PVA is gap filling, but there were no gaps to fill with the things we were building. My recollection was that we just tried the polyurethane as as experiment, but found it offered no advantage.

I build strip built kayaks and fit a laminated external stem on the bow and stern. That may be similar to what you plan to do. The laminations are usually about three or four layers of 3mm Jarrah. I just use PVA. One difference is that the whole kayak has a fibreglass skin inside and out, but I'm convinced that the PVA would hold without the glass.
Bow.jpg

If you are confident that the layers won't have any gaps at all, then the PVA would do the job. If you can't get a really good match between the laminations, then polyurethane may be better.

It depends on which PVA you use. I use exclusively Titebond 3 and I’ve never had any problems. It’s exterior grade, waterproof, and the bond is stronger than the fibres in the wood glued. Meaning it’ll never break exactly over the glue joint

I have used Gorilla brand glue similar to Tite Bond on bird mouth mast and spars for my boat (now sold)

very strong bond and easier than thickened epoxy, container recommends dampening wood on edges to be glued which I did

Cheers Paul

Originally Posted by vnx205

When I worked for a couple of years for a business that made dining tables, coffee tables, entertainment units and such things, we used PVA almost all of the time.

If the faces being glued are a good fit, the join is stronger than the surrounding timber.

One advantage polyurethane has over PVA is gap filling, but there were no gaps to fill with the things we were building. My recollection was that we just tried the polyurethane as as experiment, but found it offered no advantage.

I build strip built kayaks and fit a laminated external stem on the bow and stern. That may be similar to what you plan to do. The laminations are usually about three or four layers of 3mm Jarrah. I just use PVA. One difference is that the whole kayak has a fibreglass skin inside and out, but I'm convinced that the PVA would hold without the glass.
Bow.jpg

If you are confident that the layers won't have any gaps at all, then the PVA would do the job. If you can't get a really good match between the laminations, then polyurethane may be better.

Excellent detail in the kayak

I use polyurethane for repairs to kids toys or generally where I care more about the strength than the finish. It's a lot more forgiving of bad prep, fit or long term abuse. It's also a lot harder to get a good finish (or at least the moisture cure stuff I use is) as it tends to expand and ooze out the gaps as it cures. Less is more.

I tend to use a 'yellow' glue (aliphatic resin) for most of my woodwork projects but also use PVA on occasions.
Yellow glue apparently makes a joint stronger than the wood.

I've used polyurethane glue on shed door frames to fill some of my quickly made (i.e. not perfect) mortice & tenon joints.
It tends to go off in the bottle after about a year so I've thrown away more than I've used plus don't get it on skin because it doesn't clean off, you have to wear it off.

Wood glue - Wikipedia


Colin

Hi,
I'm a bit late to the party, but my two cents worth.
I've found that when using polyurethane glue (laminating veneers) sometimes the glue line becomes brittle and will fracture the glue with vibration (motor boats) . I've used gorilla, fuller and stickaflex brands, have similar failures with all of them.
The yanks talk about "yellow glue" and I think it's excellent and does everything that PVA does and is (in my experience) a lot more tolerant of water than PVA, but have found it pretty hard to get hold of. These guys are the only supplier I've been able to find for yellow glue in Brisbane, Nightingale Supply, Although I haven't looked in the past 10 years or so. My understanding is that the Titebond stuff is aliphatic based and I can confirm the Titebond II is definitely water proof.
While PVA is an excellent adhesive and I use it all the time, it will never be water proof, the exterior stuff is better but not (in my experience ) as good as yellow glue.

Good luck with the steam bending, I've found it to be a black art and needs lots of dark magic !

Cheers Glen