Glue Myths: 1. End grain
Why Woodworking Stack Exchange recommends it
Woodworking Stack Exchange answerers point people to it when questions about gluing end grain or grain direction and joint strength come up, as experimental evidence against the conventional wisdom.
Recommended by 1 people across 1 different months, 2016 to 2022.
What it is
Patrick Sullivan runs controlled strength tests on glued wood joints to check the common claim that end-grain glue joints are weak. The 16-minute video is the first in his Glue Myths series and reports measured results rather than shop folklore.
What people said
Strong rec Julia · 2021-10 · Woodworking Stack Exchange · on “Gluing end-grain”
Look at Patrick Sullivan's "end grain glue" video experiment on YouTube to be amazed by his analysis showing that end-grain glue joints are actually stronger than other grain orientations that have the same amount of bonded surface area. The reason that end-grain joints are dismissed is because the joint is usually small when separate end-grain surfaces need to be attached. In addition, with end-grain joints, the orientation of the grain in the wood makes it much stronger than the glue, whereas in other grain orientations, there are portions of the wood that are weaker than the glue. [this video]
Cites Graphus · 2016-06 · Woodworking Stack Exchange · on “What are the different grain directions, and how do they affect joint strength?”
Update, September 2021 We might need to re-learn what we thought we knew about the strength of glue joints..... see Glue Myths: 1. End grain [this video] from Patrick Sullivan on YouTube. Spoiler alert: end grain | end grain joints appear to be the STRONGEST!!! If this turns out to be conclusively proven by further testing and experimentation it will make for some very interesting speculation about how everyone (?) got this so spectacularly wrong, so consistently, and for so long. Edge and face gain are both longitudinal grain , where grain runs along the surface. Long grain = longitudinal grain, just less of a mouthful, much easier to type quickly too! The structure of wood, its grain, can be vi
Cites MStodd · 2022-01 · Woodworking Stack Exchange · on “Is glue the best permanent join?”
Glue is stronger than lignin in wood, but weaker than wood fibers. If you glue along the grain, the wood will fail before the glue due to the weakness of the lignin in wood, but gluing end grain, the glue will fail before the wood since the wood fibers are massively stronger than glue. To increase strength even more, taper the glued ends so that there's always overlapping fibers, the longer the taper, the stronger the resulting piece. It looks like there's a few factors in determining if a glued joint will be stronger than some other joinery: is the wood stressed along or against the grain? Are there multiple points of stress? Is stress on the glue directly, or on a wood-glue-wood sandwich?