Gluing End Grain to Side Grain

Glued butt joints hold better if you pre-wet and pre-glue the end grain briefly before the final gluing and clamping. December 2, 2006

Question
Just curious where everyone stands on cross grain gluing. I was taught that it should never be done, but lately I have seen a few cabinetmakers doing it.

Forum Responses
(Adhesives Forum)
From Professor Gene Wengert, Sawing and Drying forum technical advisor:
Do you mean gluing of end grain (or wood with quite a bit of end grain, such as a 45 degree miter)? If you do glue it and have enough adhesive (end grain is really absorptive), you can develop some strength, but not as much as with side grain. For this reason, historically, we have used mortise, biscuits, etc. for end grain joints.

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From contributor S:
Oddly enough, this very question came up in our shop two days ago when one of the cabinetmakers had to disassemble a face frame (because he'd built it backwards... just had to give him a little dig for that one).

He thought the stile would just snap away from the rail's end grain butt joint after he took out the pocket screws. After he'd rapped it with a hammer 5-6 times and it was still tight, he took one last mighty swing at it. It broke alright, but not at the joint... The stile split in half, but the glued up butt joint was still intact.

A long time ago I'd shown my guys how to pre-glue end grain, but no one until now had any reason to test it. I don't think they actually believed it worked; they probably thought the old man from the old school was crazy, but they did it anyway to humor me. They believe it now, and the others have run their own tests with pretty much the same results.

Lightly dampen the end grain with a damp cloth/rag, spread on a thin layer of glue and let it sit for a minute or two. Then glue as normal and assemble. The problem is that the end grain absorbs the glue and starves the joint, robbing it of any real strength. By pre-gluing the end grain, you're essentially blocking the flow away from the joint; the glue pretty much has to stay put.

An end grain joint still won't be as strong as a face/side grain joint even with pre-gluing, because if you think about it, you're really gluing holes together face to face. There's simply less material for the glue to grab on to. But pre-gluing it will strengthen the joint considerably. Try it and see.

P.S. The minute or two they have to let the pre-glue set is the time they now take to pre-assemble the face frame :)

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From contributor B:
Curious… When I was turned onto pocket screws by a more experienced cabinet builder, he said he liked them because they can come apart, and proceeded to explain a job where they had to reconfigure the cabinets after they were built. I skipped butt joint gluing, but on my next project, I will probably consider using glue, especially on the cabinets that will hold heavy pots and pans. Since I've already assembled about 1/2 of my new cabinet face frames without glue, I see no point in second guessing myself.