Which glue is strongest? Testing with my computerized tester.

Testing different types of woodworking glue on my glue strength testing apparatus.
First with construction lumber, then with maple hardwood.

[WoodByWright]

Thanks for shout out. On the test I did, The long grain to long grain is actually a cross grain connection. So they should be fairly similar in that. but with the rig I was using, it puts more pressure on the glue joint itself. I would to try it with your computerized laod cell. That is so sweet. Nice work. I always love watching your tests. Lots of great analytical thought-through on that.

[zasgat]

Hi Matthias, I work as an engineer for one of the top 3 adhesive manufacturers. What you measured is the torsional shear strength of the wood glue. One interesting thing that you pointed out is that the different failure mode in each sample. You can see the "adhesive" failure when the bond between wood and glue failed leaving a clean surface. Most appeared "cohesive" meaning that the glue failed in the bulk structure leaving adhesive on both sides. The wood breakage was a substrate failure and these results are typically discarded. A factor to account for when comparing to Wood by Wright's data is that your setup includes leverage from the force applied at the end of the wood block. Also important is each glue's reliability ratings like humidity and temperature that you mentioned. More rigid glues like superglue also might not be able to and the CTE mismatch during temperature swings.

[chrisa]

These “project farm style” comparison videos with Matthias’ approach to testing are really good.

[AllBikesShredits]

Matthias, the amount of content you put into one 13 minute video other channels don't manage to put into 50 minutes. Thank you for always cutting straight to the chase!

[chrisgriffith]

Fun fact about wood gluing my late Great Uncle Ralph taught me back when I was a child: (Using plain Elmer's wood glue circa 1986) when applying wood glue, brush it on all surfaces being glued, and let it cure for about a minute, then apply a second coat quickly and then put the pieces together, the extra tack and time for the glue on the wood helps evenly penetrate the surface of all the pores in the woodgrain, also helps the glue to remain wet longer when you reapply, thus giving it a longer more even cure rate in the end, and will not "flash cure" (when the wood wicks away the moisture of the glue too fast) thus weakening the glue's bond into the wood. Moistening with water will only dilute the bonds made on the surface of the wood, so that will not work. I still have the example of this very lesson, a desk I made for college, which underwent no less than 6 moves cross country, and none of the joints have failed to date.

[JohnHeisz]

I'll pop in early and say that you used the wrong construction adhesive. It has to be PL Premium - a polyurethane construction adhesive, and not the normal subfloor adhesive you tested.

[Frank-bhcm]

This is great content! Thanks for buying all the glues, building a load tester and writing the software.

[jerry-p]

As always, fun to watch your tests. Loved it when the samples popped off and flew through the air!

I've been using the Gorilla wood glue for the last few years and have been quite happy with it all around. Nice to see it showing well in the standings!

[cwtrain]

Something about the meeting of wood, mechanics, and scripting just tickles the hell out of me. Bona-fide renaissance man.

[johnballmore]

Love the quality of your testing, and the conclusions and personal opinions you provide us with. Keep up the great work!

[AmandaRPatterson]

I do appreciate your scientific approach to testing things. Nice video!

[jeffmorrison]

I LOVE these in-depth analysis of specific subjects!!
Thanks again Matthias!

[IanSmithKSP]

I use construction adhesive regularly for, well, construction. What I’ve learned is there are many different kinds for specific purposes. DAP4000 for example has very high PSI ratings for cross-joint strength. So when your subfloor expands and contracts seasonally, you don’t shear the glue off. I imagine that you used one of the glues that’s designed to withstand expansion, and so is weaker (but less brittle). The more brittle stuff might make better furniture joints

[bhoola]

Like most other video, this was the best you did for your woodworker viewers. Thanks dear.

[AppliedScience]

Here in California, at least, "construction adhesive" used to be a thick tacky paste that smelled strongly of hydrocarbon solvents. It worked well for large gaps and disparate materials, but the law now limits VOCs, and all construction adhesive is basically latex paint, which is slow drying, and weak. I agree that cheap wood glue is still the best for tight fitting wood joints. Thanks for doing the tests!

[TheJamie]

Love these testing videos. Been watching your vids for years, and all the testing videos you've ever done are always my favourite. I just love cool graphs!

[Peekul]

Man, you crack me up. Watching your invention launch wood across the room 🤣 Super smart guy just doing your thing. I appreciate you!

[MrConacher]

Fascinating comparative analysis. Thank you for this.

[robertbamford]

Very interesting. I think it shines an interesting light on “with modern glues, the wood will fail before the glue.” Thanks for the analysis.

[xlillo]

Good video. Over the past 20 years I have found the PL400 to preform far better than how it resulted in your testing. Specifically which use on framing lumber, plywoods, and solid hardwood flooring. When having the dismantle things Ive built with those materials the PL has always out preformed the wood strength. One variation is that my joints have always been screwed or nailed in addition to the PL400.

The Gorilla wood glue was a surprise, and I'll probably be moving to that from the Titebond for carpentry projects.