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I bought 2 inch thick oak decks that have been seasoned for a year outside. I would like to start gluing them together i.e. to make a bench top (and eventually a whole woodworking bench)

What do I risk? Is it possible that if I glue it together it will later crack or deform?

  • Not sure if you know this already but there's an oft-repeated rule of thumb for drying, a year per inch of thickness. While this is a gross simplification it does give you some inkling that you haven't yet waited nearly long enough for the wood to be as dry as it can get but this is only IF the wood was green when you got it. If the wood was already dried, even if only partially, the picture is completely different. – Graphus Nov 12 '18 at 20:27
  • Something else worth mentioning that I only just now thought of, glue type makes a huge difference to this query. Epoxies won't glue well to anything damp so they're very much countra-indicated here, and the commonest woodworking glues (PVAs, both white and yellow) bond less well to wood that's not below a certain MC, but note they do work well across a wide range. On the other hand though, foaming polyurethane normally requires that one side of the joint be moistened to activate the glue properly, so for that type of glue damp wood can be a positive advantage, not a detriment. – Graphus Nov 13 '18 at 13:54
  • I also suggest a title edit, partly because "... will happen..." is not good since certain issues are possibilities, not certainties, and also to more accurately reflect what it is you're actually asking about. I'd suggest something like, What problems might occur attempting to glue wood that hasn't been fully seasoned? – Graphus Nov 13 '18 at 14:01
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Your assumptions are correct: the wood will move as it acclimatizes to any indoor space, and your glued-up joints and panels might move a lot as it dries. Depending on total moisture content now and in your shop (and, of course, exactly how the joints are made, since wood moves more across the grain than with it) it might not be a disaster, but if that lumber decides to move, there isn't going to be any glue joint in the world that keeps it from moving.

Even if it was covered outside, the moisture content will be a lot higher than most indoor spaces in North America. Though, since you are making a bench, it is possible that you are in a partially heated shop, which might be a bit more damp. Still, the moisture content would ideally be in the single digits (<10%) before you start working it, and for installation in a fully heated indoor space closer to 6%.

To reduce checking and cracking, the simplest thing you can do is to stack and sticker it indoors for about a month prior to working with it. You should paint the ends with end-grain sealant so you slow down drying that can cause checking. (The usual advice here is to not use latex paint, but proper end-grain sealant.)

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  • Thank you for this answer. I did already put it indoors - the exact place where the bench is going to be. A month doesn't seem to be a lot of time, I was afraid that I should be waiting for a year or so. I also ordered a moisture sensor to see where I am with the % value. Somehow I suspect that the wood might have even been seasoned less than a year.. – kubal5003 Nov 12 '18 at 15:31
  • Yeah, a month is really just a rule of thumb. Since you are buying a moisture meter just test it in a few places over a month or so and once it stabilizes you should be ok. Make sure you stack it on stickers to get air movement. (BTW, I appreciate the checkmark, but you should see if others come along and give you better answers!) – jdv Nov 12 '18 at 15:36

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