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dvanvleet

Glue line creep

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Ok, I keep having some kind of an issue with glue lines; this may be a bit long, but I'm going to try and cover all the details. Here's the summary. I have noticed that after I glue, say a table top, I let it dry overnight. Then I typically sand from 100 grit through 220 so the top is super smooth. I use a raking light to ensure all glue is off the surface. I then use either OSMO or tung oil as a finish; usually two coats. What I have been noticing is, a week or so after the piece has been sanded, finished and dried, I can feel a micro line protruding on the glue seam; you can catch it with your finger nail.

Some important notes:

  • the wood is dry, 10% or less
  • wood species doesn't seem to matter
  • Using Titebond 2
  • Doesn't matter if I raise/wet the grain or not
  • Shop is environmentally controlled; both temp and humidity

So what in the heck is going on here? It is very frustrating because everything is super smooth right after I finish it, but a few days later, the line appears and you can definitely feel it.

Thoughts?

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I have occasionally experienced that as well, but have no explanation. It would be nice to know what the cause is.

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It seems to me that there is still a reaction going on with the glue, long after it seems to be "dry". I've noted the same thing happening on several pieces I have made. I don't think the joint is slipping, it seems more like the glue is expanding out of the joint. 

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Why did you use TBll? I never use TBll unless there moisture involved in its final destination....

I've never experience glue creep. The only things I can think of is wrong glue, not enough pressure when applied or not allowed to dry enough

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I use mostly TB2 and as I said, have only occasionally had the issue. My gut tells me it has something to do with the width of the glue line. If my jointing was perfect, it doesn't seem to happen. But I've not kept records & the sample size is to small to be significant.

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Call Franklin (i.e. Titebond).  The number is on the bottle and the call will be answered by someone who knows more about adhesives than you thought possible.  

Then report back :).

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Personal opinion is that a slightly slightly imperfect glue joint and too much glue is leaving enough glue in the joint and allow it to expand causing the ridge between boards. I tend to minimize squeeze out as it's a mess to clean up and wastes glue. I checked the major panel glue ups in my house over the last 3 years and none of them have this ridge. Some of my older projects before I had a jointer do exhibit this a bit I also was a bit heavier with glue 5 years ago.

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Ok, so to answer a few thoughts. First, the glue lines are tight and invisible; no gaps at all. Some of the glue joints were even spring joints. Second, the pieces were often left to dry for 24hrs or longer in a climate controlled environment; plenty of time to dry. 

What is strange is this only happens after the oil finish has been applied and allowed to dry/cure for several days. It is sort of like the oil, as it cures, is micro-shrinking the wood fibers and the glue line is left slightly raised. 

 

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