Adhesive Failure in a Cherry Glue-Up

      Troubleshooting a glue joint failure with Titebond adhesive on solid Cherry. October 11, 2012

I glued up 41/2" wide cherry, laminated face to face, and let in clamps for 13 hours. When I took it out of the clamps it started to come apart like the glue didnít even hold at all. I used the glue the day before to glue panels and worked fine. It is Titebond 3. I do not know of it freezing. Does anybody have any ideas why?

Forum Responses
(Adhesive Forum)
From Jeff Pitcher, forum technical advisor:
How was the temperature? Does the glue line look really white, like chalk? Also, look at the areas that failed. Is there glue in them? Did it pull any fiber? Is the glue line glossy where there was failure?

From the original questioner:
The shop temp is around 60 to 70 degrees and the glue squeeze-out looks normal, but the glue inside when apart was chalky colored. There was no fiber pull. I took and popped them apart with little effort, all six sets. There was glue in them and I glued both sides. I rolled the glue on to them fairly thick - I just do not understand why the day before the glue worked fine. I think I am going to throw the half gallon I have left away as Iím afraid to take a chance on a bunch of panels coming apart on a job already installed.

From contributor G:
I was having the same problem the other week with cherry also - Titebond II though. Temps were good, glue was good, and the glue-ups fell apart on the gluelines just by dropping the boards on the table. Next day, same glue, same cherry with a new jointed edge and it worked fine.

I have only had glue failure on cherry, never any other wood. I have only ever had two glue failures in my 20 years on the job and they were both cherry. Then this job came along and I had all my panels fail, nine of them.

If you saw chalky residue then temperature was the cause, without a doubt. If the area was warm and the glue was warm maybe the stock was cold. Itís hard to tell because it has insulatory qualities and never really feels cold to the touch. Make sure your wood is warm before glue-ups. You probably did the glue-up first thing in the morning, right?

From Jeff Pitcher, forum technical advisor:
It was almost certainly due to cold board. Crosslinking PVAs such as Titebond III or MPA II tend to have a higher chalking point than traditional PVAs such as Titebond. I've seen them chalk as high as 65F. Once this occurs there is little or no bond.

Contributor G - your experience with the cherry is a classic example of why it's important to use freshly machined wood when gluing. Contaminants such as oils migrate to the surface of the wood often causing significant interference with the bond.

From contributor G:
You might have misread something I said or I wrote it wrong. All of my glue ups are jointed and assembled within minutes. I have never done it any other way. It is always possible that I had some burnished edges, the cherry was quite chippy and I was going pretty slow on the jointer to prevent it. However, I can't see all (but one) boards failing because of that. That one board that made it was the mystery too.

From Jeff Pitcher, forum technical advisor:
I guess I misunderstood, I thought you indicated that when you machined the cherry and then glued; it was fine. I always tell people that the glue doesn't have brains so it can't decide to stick in one case and not another, unless there is some other variable at work. The fact that it stuck on one of the panels indicates that there was a problem on the other eight. Burnishing would do it although I'm with you. It seems odd that of nine panels only one would come out unburnished.

From the original questioner:
Jeff - what is a better wood glue for gluing panels in lower temps?

From contributor G:
I pretty much use TB II exclusively. I have never had a failure that wasn't immediately obvious. Usually if the glue holds initially, it will be good for life.
If your jointer is sniping ever so little at the end and you don't notice it, then it is possible that the joint might let go at just the end because of stress.

From Gene Wengert, forum technical advisor:
I see nothing that indicates a drying or moisture issue. I do think that because you slowed down you may have burnished the wood making the surface unfit for gluing. Have you heard of the water drop test? Put a drop of water on the surface to be glued and the drop should disperse within a minute or two if the surface is active for gluing. You can reactivate the surface by very light sanding - one pass with a block sander in many cases.

Also, remember that it is the wood temperature (not the air temperature) that is important, so it make take quite a few hours for a cold piece of wood (stored in an unheated area) to warm up.

From contributor H:
Why TB III? TB II is excellent, TB IIextend is as well. I personally don't like TB III. I did some glue-ups with it when it first came out and experienced "line jump". The job was with sapele which generally is nice to work with. My MC is always at 6-8%, and I don't rush things, yet after everything was scraped, then sanded, a day later I had jump, and I hand sanded down cause I thought maybe it was heating up. That was on Saturday, and I came in Monday and the thing was up again, not as bad as before, but I could still feel the lines though. I sanded it again, sent it out, kept my fingers crossed, and still haven't been called about it (two years). I don't want to go through that again.

From contributor A:
Contributor B - your description of Titebond III is common. It resembles white glue in that it does not dry hard like Titebond I. I have experienced your problem of cutting back with sandpaper. It does not matter how many times you sand it. It will cause awful print through when painted. I only use Titebond I for interior, Titebond III exterior, and epoxy for longer dry times and specific exterior projects.

From contributor K:
We experienced a similar problem one time - and the cause was determined to be storing the glue pail on the concrete floor. About half of a five gallon pail was rendered unfit so it was discarded and ever since all five gallon pails of glue are kept up on a shelf - about six feet off the ground! Where do you store your glue?

From Gene Wengert, forum technical advisor:
Contributor B and Contributor A both describe a problem that is common for old glue or glue (I guess I really should say "adhesive") that has not been stored correctly or is applied too cold or to cold wood. As the adhesive get more sophisticated, they also seem to get more sensitive to improper handling and aging.

From the original questioner:
I store my glue on a shelf in a heated closet that is thermostat controlled. I think it was cold wood as was stated.

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