The general wisdom is that wood glue sets harder than the original wood, but experiences and testimonies on this seem to vary.

Two weeks ago, I replaced some worn hinge screws on a heavy interior door. I reused the existing screw holes, applying some PVA glue (Titebond III) to strengthen the threads just in case.

I'm examining these screws now and noting that they are holding fast.

However, the threads themselves, though very solid and secure, are slightly gungy and sticky, with a tough treacly consistency when the screws are removed. The glue seems to have penetrated the surrounding wood, altering the material properties of the pine around the threads.

At two weeks, I had expected the timber to be back to its original consistency.

Bearing that in mind, what is the mechanism of action of PVA glue, and what seems to have happened in my case? Can I expect the pine to return to a hard/dry consistency over time?

  • You filled the hole with glue and no additional wood material? Nov 9 '19 at 14:18
  • 1
    Next time, mix sawdust into the glue, or push wood splinters into the hole along with the glue. And definitely wait for it to fully harden before putting in the screws. Nov 9 '19 at 15:46
  • That would be helpful if the holes are stripped. Not so much here, where we are simply cutting new threads, preserving orientation and diameter of the existing screw holes.
    – Brybeck
    Nov 11 '19 at 18:14

The glue isn't curing

Because it has no exposure to air.

Effectively, you haven't applied it, just put it in a different bottle.

The moisture of the stuff is softening the pine wood around it.

You're lucky, too. If it had cured, you would not have gotten that screw out in a million years. You're really playing with fire on this one.

Leave the screw out for a week, see if that helps.

And if you want to do that in the future, either a) drill it out and glue in a dowel of similar softwood, b) mix a thick slurry out of sawdust and glue, or c) if you suspect wood deterioration, hit it with an epoxy product called Git-Rot, which will soak into the wood. But in all cases you wait for glue cure before putting any screws back in. And if you want the glue to cure at a definite, positive rate, use epoxy glues.

  • Failure to cure is the most obvious explanation, but the glue was left to cure overnight. I don't think wood glue requires air to dry like epoxy, but does so via moisture loss, which would be accommodated by any natural wood substrate. Even more so by the two week stage.
    – Brybeck
    Nov 11 '19 at 18:18
  • epoxy doesn't require air exposure to dry, not sure where you got that. Epoxy partly "dries" as the liquids chain up into a solid, which is called curing. It sounds like we disagree on technical basics. Reality seems to be tiebreaking. Mark Twain is attributed to saying, "it ain't what you don't know that gets you in trouble, it's what you know that just ain't so!" Nov 11 '19 at 19:15
  • You may be right about epoxy, though it's interesting you mention doweling in the context of wood glue. (My understanding is that PVA in that situation also cures by moisture diffusion through wood). I do appreciate your answer, though we didn't want to dowel in this case because the holes weren't stripped out.
    – Brybeck
    Nov 12 '19 at 5:58
  • Git-Rot is specifically for this. It even has an applicator with a needle nose, designed for getting into screw holes. And the small kits are so cheap you won't believe you're in a chandlery (marine supply, notorious for being overpriced). Nov 12 '19 at 16:00
  • I've had a look at the threads and thankfully no rot. Git Rot is interesting though. I might look into it some more to see its full range of applications.
    – Brybeck
    Nov 12 '19 at 18:50

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