Glue Myths
- Thread starter KenB259
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Wow that was excellent!
monophoto
Member
Very interesting, but not surprising. It is often the case that facts can be distorted through oversimplification.
My recollections of the Teachings of the Master (Norm Abram) are that he never said that end-grain cannot be glued, but rather that he said that extra care had to be taken to get a strong end-grain joint compared with a long-grain joint. Specifically, he made a point of insuring that glue was applied to both surfaces, and where possible, he preferred using polyurethane glue because it penetrates into the fibers of the wood better than PVA glues (and note that Mr. Sullivan speculated that penetration of the glue into the end-grain fibers was a critical factor in determining joint strength).
However, I have a lingering question - does the length of the joint. matter? In Sullivan's tests, the joints all had the same length, but I wonder if the joint strength might increase if the joint length were longer - for the reason Sullivan explained, namely that the strength of the joint is limited by the strength of the lignin between the fibers of the wood parallel with the joint; I would like to see tests to determine if making that joint longer would increase the strength of the joint.
My recollections of the Teachings of the Master (Norm Abram) are that he never said that end-grain cannot be glued, but rather that he said that extra care had to be taken to get a strong end-grain joint compared with a long-grain joint. Specifically, he made a point of insuring that glue was applied to both surfaces, and where possible, he preferred using polyurethane glue because it penetrates into the fibers of the wood better than PVA glues (and note that Mr. Sullivan speculated that penetration of the glue into the end-grain fibers was a critical factor in determining joint strength).
However, I have a lingering question - does the length of the joint. matter? In Sullivan's tests, the joints all had the same length, but I wonder if the joint strength might increase if the joint length were longer - for the reason Sullivan explained, namely that the strength of the joint is limited by the strength of the lignin between the fibers of the wood parallel with the joint; I would like to see tests to determine if making that joint longer would increase the strength of the joint.
Jim15
Member
Thank you for posting this.
CAS
Member
I watched that video a few days ago and was impressed with the presentation as well as the results.
Kenny Durrant
Member
I learned a few things. Thanks.
rherrell
Member
I glue end grain quite a bit when making rocking chairs and this method has never "failed".
Spread glue on end grain and let it sit for 15 minutes, this allows the glue to soak into the open pores of the grain. Right before clamping spread another layer of glue to "re-wet" the previous layer. Clamp as usual.
I've never had a failure using this method.
Spread glue on end grain and let it sit for 15 minutes, this allows the glue to soak into the open pores of the grain. Right before clamping spread another layer of glue to "re-wet" the previous layer. Clamp as usual.
I've never had a failure using this method.
rherrell
Member
I forgot to mention one very important point...
End grain "sucks up" the glue really fast, if you apply your glue and clamp right away you end up with a "glue starved" joint which I believe is the main cause of failure for end grain joints. By allowing the glue to soak in for 15 minutes and then re-applying more you avoid a dry glue joint.
I use Titebond lll glue, it has a little more open time than plain Titebond. Never used Polyurethane glue so I can't speak to that.
End grain "sucks up" the glue really fast, if you apply your glue and clamp right away you end up with a "glue starved" joint which I believe is the main cause of failure for end grain joints. By allowing the glue to soak in for 15 minutes and then re-applying more you avoid a dry glue joint.
I use Titebond lll glue, it has a little more open time than plain Titebond. Never used Polyurethane glue so I can't speak to that.