Putting together a recent project and this board cracked. Looks like structural failure (at first I thought perhaps a defect in the base material, but nope). I can get it to open/close a small bit by pressing or deflecting it.
It is not structural in that the piece is not going to fall apart. Worst case the lower part of this seatback falls completely off - still functional.
But I am going to do 'something' to close it up, some ideas include:
Just let the finish seep in (likely general finishes urethane) then clamp it to close up and if successful some will squeeze out
Hit it with superglue. Some time ago I had some Loctite 420 - it was very thin and wicked very well. I have never used superglue on wood though.
Countersink a couple screws from the underside (hidden), to pull it together.
Or some combination there-of. For any of them, I will try to make the crack bigger to get something to wick as deep as possible, then clamp until it dries.
Welcome opinions and other ideas (its not worth re making the piece, simple everyday bar stool and likely to get beat up over time)
-C