Glue Myths Video

[andrew whicker]

Many of you are really reaching to find something wrong with his experiment, but deflecting to entirely different subjects.

- "But what about wood movement over time?"

Notice he never mentioned this. The thing he was set to disprove was quotes that he showed at the very beginning, like this one: "Any joint that butts End grain to End grain will be weak because you're gluing wood fibers at their porous ends instead of along their sides."

He completely proves that to be wrong. Notice that quote said nothing about "well, obviously wood growth is a huge issue and that's why you can't glue end to end".

- "who would glue up two boards with the same exact geometry in real life?"

How else do you test something other than using the same scenarios to understand their relative nature? Why would you compare a 12" side to side joint to a 3" end grain joint? What would that prove?

[andrew whicker]

The side panel is glued and screwed to the stile, not the rail.

[Mark Bolton]

Many of you are really reaching to find something wrong with his experiment, but deflecting to entirely different subjects.

I think the point thats trying to be made is one thats been made over and over but for whatever reason people want to fight it... the glue joint itself is for the most part a fixed entity trying to constrain the wood which is a non fixed entity. So trying to defend the integrity of a glue joint in any capacity really solves nothing because all your doing is trying to push the boundaries of the joints capacity as far as possible without experiencing a failure when the real issue is, just adjust your practice as to not push the joint close to failure (to avoid a failure/callback/return/customer complaint/wife complaint/whatever).

Endgrain to endgrain is a disaster just as stated in regards to gluing 2 2x10's together end to end and walking out over a 50' drop. You'd never do it. Strip laminated plank, Id walk out there all day. The video doesnt really achiever anything other than in the most delicate/light of situations where someone may glue endgrain to endgrain and it shows clearly that that joint is extremely brittle (ever chiseled glue off your bench? its like glass? same brittle in an endgrain glue up).

It just becomes common sense.. but if you have to learn things the hard way have at it.

[Stan Calow]

I think it was a good engineering test for one very specific mode of failure, and wasn't intended to cover all possible joinery scenarios. I too have alway heard, from magazines, books, videos, TV, etc., that end-to-end was always a weak bond. The rest of the stuff about long-term movement, bending, and sharp impacts, are all other things that can be tested and reported as well, but doesn't invalidate this specific, basic study. And its not always necessary or wise to have the strongest possible joint in the world.

[Doug Garson]

The video doesnt really achiever anything other than in the most delicate/light of situations where someone may glue endgrain to endgrain and it shows clearly that that joint is extremely brittle.

It just becomes common sense.. but if you have to learn things the hard way have at it.

Not true, the side grain joints failed in the wood at lower forces than the end grain glue joint failed in the glue. So the end grain glue joint is stronger than the side grain wood but not as strong as the long grain wood. Thus the strength ranking is
1- long grain wood,
2- end grain glue joint and
3- side grain wood.

[Mike King]

Miter joints are end grain to end grain…

[Lee Schierer]

I was at a wood show a number of years ago. There was a booth selling Hi-Pur glue that glued up samples of wood using their glue. The joints were all end grain to end grain. Shortly after gluing the pieces together they would hand the samples to people and challenge them to break the joint. None of the joints failed. It was obviously a very strong glue. The problem is that Hi-Pur glue is expensive.

From my own experience, I read an article about failure of miter joints. The thing that stuck in my mind was that miter joints are essentially end grain joints. The article suggested that the reason for most failures was glue starvation due to the grain pulling the glue out of the joint. By simply coating both sides of the joint with glue prior to assembly, they demonstrated that the joints were 2-3 times stronger than the same wood joint with glue applied to only one side. My experience has confirmed that practice.

With regard to the video, his conclusions were valid, BUT, that doesn't mean that 99% of woodworkers are wrong. We don't use end grain to end grain joints where maximum strength is required for load bearing because as the video showed, long grain without any joint is 6-8 times stronger than any glue joint. Can I glue up a checker board with squares of walnut and maple and expect it to be strong enough for a checker board, it certainly will. Would I use and end grain joint is a structural application, certainly not.

[Mark Bolton]

Millions upon Millions of face frames use edge to side grain on glue up.

This is true and the way we do it with pocket screws like many others. But if youve ever had the need due to a customer change to pop out a rail on a faceframe thats already assembled and finished you'd see that simply removing the pocket screws and with a very small mallet and a light/sharp tap, the rail (end grain to long grain) pops free like a charm and comes out completely clean. Whether you double coat the end grain or not and end grain joint just doesnt have the cellulose/cellulose surface area contact that a long grain joint does.

I think he even states it in the video and its just common sense. A board is just a bundle of straws. Glue up a bundle of straws and lay two bundles side by side and glue them together. Take two more and glue them end to end. The contact area end to end is just where the ends of the straws touch. The remaining area is filled with brittle glue that is simply glued to itself. PVA isnt as brittle as CA but scraping of your bench top is plenty brittle enough to leave a shard that will send you to the first aid kit for a bandaid which is why a sharp tap with a mallet breaks the rail/stile free on the faceframe. Its just shearing the brittle glue line because there is very little cellulose/cellulose surface area glued.

Ive dropped several faceframes in the shop and even pocket screwed the joints will separate with a very light drop.

[Jim Dwight]

I do not find fault with the technique he is using to do his tests. I find fault with his premise that what we care about is integrity immediately after glueup. I don't make things to last a few minutes or days. He pretends to have proven that end grain joints are strong and reliable. But he doesn't address wood movement so he hasn't proven anything useful at all.

If he wants to do a meaningful test of his premise he needs to address wood movement. Change the moisture level in the wood pieces and see what happens. I am confident I already know what will happen.

He succeeded to get us to watch his video and comment about it so he probably got what he wanted.

[Edward Weber]

Nothing new, nothing discovered, nothing debunked, absolute nonsense.
As has been stated by some, he presents his findings in a distorted way, as to make it seem to contradict what we all consider common knowledge about glue joints.

The saddest thing to me is that there are 5.6k people that liked this video.
I won't go into what joint is or isn't strong, I'll only say that pva glues have proven to perform incredibly well if used correctly with proper joinery and construction techniques.

[Kevin Jenness]

But if youve ever had the need due to a customer change to pop out a stile on a faceframe thats already assembled and finished you'd see that simply removing the pocket screws and with a very small mallet and a light/sharp tap, the stile (end grain to long grain) pops free like a charm and comes out completely clean.

Interesting observation, and completely contrary to my experience. When I have dismantled pocket screwed frames after a couple of minutes they almost always tear the side grain out. Perhaps the difference is in the wood species used?

I wouldn't rely on an unreinforced end grain joint as seasonal wood movement would likely break it loose over time, but despite my initial skepticism I have come to rely on pocket screws with glue for face frame joinery.

[Mark Bolton]

But if youve ever had the need due to a customer change to pop out a stile on a faceframe thats already assembled and finished you'd see that simply removing the pocket screws and with a very small mallet and a light/sharp tap, the stile (end grain to long grain) pops free like a charm and comes out completely clean.

Interesting observation, and completely contrary to my experience. When I have dismantled pocket screwed frames after a couple of minutes they almost always tear the side grain out. Perhaps the difference is in the wood species used?

I wouldn't rely on an unreinforced end grain joint as seasonal wood movement would likely break it loose over time, but despite my initial skepticism I have come to rely on pocket screws with glue for face frame joinery.

Its all Ive ever used (pocket screws on 1.5" face frames, glued. Ive done this with several species because unfortunately it seems in my world people decide they want something like a trash pull out after the fact so your left knocking out a rail or rail and stile to make a full height opening where a door/drawer was. Not sure about your method whether your levering them apart or what but a sharp vertical tap (up or down) shearing the glue line and every one Ive ever had to do comes out clean as a whistle other than a light scuff, filling screw hole, and a bit of finish. Most glue/adhesive joints Ive ever dealt with are very weak in shear for all the reasons mentioned in these type of threads.

[Doug Garson]

Nothing new, nothing discovered, nothing debunked, absolute nonsense.
As has been stated by some, he presents his findings in a distorted way, as to make it seem to contradict what we all consider common knowledge about glue joints.

The saddest thing to me is that there are 5.6k people that liked this video.
I won't go into what joint is or isn't strong, I'll only say that pva glues have proven to perform incredibly well if used correctly with proper joinery and construction techniques.

Mind explaining how he "presents his findings in a distorted way"? Seems to me he presented his findings in a neutral way. He glued up the samples, let the glue cure, tested to failure, recorded the results and displayed them in a straightforward graph.

[Frank Pratt]

Mind explaining how he "presents his findings in a distorted way"? Seems to me he presented his findings in a neutral way. He glued up the samples, let the glue cure, tested to failure, recorded the results and displayed them in a straightforward graph.

My issue was with how he intro'd the video with all kinds of hype about how he was going to turn the world's collective knowledge of wood glue on its ear. As I mentioned earlier, all he did is show us what most any experienced wood worker already knows. There was literally nothing new there.

Or maybe he's just a woodworking noob who just discovered this & wanted to share it with the world. (and get beaucoup views)

I have no problem at all with his testing methodology. Indeed, it was very good.

[Edward Weber]

He proved nothing other than wood glue is stronger than most wood along the grain and not as strong accross the grain.
Most of us knew that already