Why didn't my spruce glue?!?!

[Bewildered]

I glued up a panel of spruce using TBIII. It has been stored inside for 20 years (the first 18 as part of a neighbor's staircase) so it is dry.

When I trimmed the ends, the pieces fell apart. That has never happened to me in the hundreds of hardwood panels I have done, so I was very surprised. Each side has glue on it, but it just didn't hold. I clamped the panel to a table and pushed down on it and the joint opened up. I think it is only held together by the three biscuits I put in. Now I wish I had used four!

What caused this? I glued up some pine before and it did fine; is it something about spruce?

I have a very thin glue/chalk (Captain Tolley, if you have never heard of it, it is great product) and laid some in while opening up the joint a hair. Now I am gently clamping and hoping I can salvage these panels. I will know in a few hours.

[Swingman]

What's the ambient temperature of the glue, the wood, the shop, and how old is the glue?

[nailshooter41]

Those would be my first questions, with special emphasis on how old the glue was, and how it had been stored. Also as suspicioned above, in my experience, cold weather makes proper adhesion much more difficult.

Way down south here we don't have the luxury of all the hardwoods at our disposal, so in the early day of building we had a lot of spruce and pine used. When properly prepared (just like any other wood; clean, joined properly, etc.) I have found that he glue joint was actually stronger than the wood.

Robert

[Bewildered]

Glue is about 6 months old, I have been using it for about 2 months, and everything was maybe 65 degrees. I used it a couple days ago for 4 viraro panels under the same conditions, and they are perfect; well, at least the cutoffs held together normally, so I trust they are perfect.

[Father Haskell]

Do another viraro glue up with the same glue. If it holds, you can eliminate at least one variable.

Isn't the scientific method fun?

[Nova]

Were the glued edges of the boards freshly jointed. If not I'm thinking maybe sap sealed the edge preventing glue absorption.

[dpb]

Still didn't hear what kind of glue which would be interesting to know...

Other possibilities could include excessive clamping pressure resulting in too much squeeze out or not enough glue to begin with.

Oh, another thought--not a polyurethane glue, perchance? They rely on moisture for a cure and 20 yr old material might be really, really dry on the surface and not get a good "cure".

[Bewildered]

I don't remember precisely, but certainly within 24 hours of gluing.

[Bewildered]

Good suggestion; just because the glue was good last week doesn't mean it is this week. I glued up some oak scraps; it is plenty strong. So, it is not the glue.

[Swingman]

Something ain't right ...

Only you can make the decision, but, if it's an important project, and considering what happened to your cutoff ends, I would give some serious thought to re-ripping the glue lines on the TS and re-gluing the panels. You can easily re-cut your biscuits in the same slots if you don't have room for new.

Much easier now if you're in the glue-up mode, than at some future date.

BTDT ... more than once. Good luck in any event.

[Bewildered]

I worked some "Captain Tolley" glue in the crack that opened when I forced it apart, and clamped it. The cutoffs from the other side seem pretty good with the new glue (I cut one end and stopped in distress when the cutoffs fell apart). But no, I don't trust it. I stuck a bunch of pocket screws in to be sure. They are shelves in a table going behind the couch, so there won't be much of any load and will never be seen. Between the biscuits and the pocket screws it has to be good.

I just wish I knew what caused the problem; it had to be something about the spruce. I guess I will play around with some of the spruce scraps. Or maybe I will see how good TB's customer service is.

[Joe]

Did you re-joint the edges of those 20 year old boards before gluing? Wood that sits too long (and 20 years is plenty long) often won't take glue. A quick test is to put a drop of water on the edge. If it stays beaded up like the board was waxed.... not a good sign.

Hope that helps. Otherwise, I've nothing. It's a mystery.

jc

[George]

Even that may not be enough with a resinous wood like spruce. Water-based glues will find no way in, even on surfaces minimally joined, a process that produces some heat and flow on a machine, and lotsa drag on a plane.

[Bewildered]

Are you saying TBIII simply doesn't work on Spruce?

I am dying it with a water based dye to "match" the viraro top I am putting on, and it stains okay; so it will take some water. Maybe just not enough for a glue bond.

(I am building a couch table; the only thing that will ever be seen is the top, so I am using up some spruce for the legs and shelves; as much to get rid of it as to save money.)

[dpb]

...

OK, I'm slow on the uptake--I finally figured out what "TBIII" is... :)

I would think it _should_ work fine. There are a lot of different woods that could be sold under the general moniker of "spruce" and some are more resinous than others. I can't think of any specific spruce I've used TB III w/, but have with a lot of pines and other "white woods" which typically are mixtures of spruce/hemlock/??? and also w/ Doug fir with no real problems.

I did a quick look on the Titebond site and didn't find any proscription against spruce or other similar woods. It does point out in general application notes for TB III that soft woods do need lower clamping pressures as opposed to hardwoods, so there is that variable to consider. Also, it does note that for oily or high in tannic acid to use a wipe of acetone before gluing to provide a clean surface for adhesion. Might investigate those factors.

There is a technical service link to them at the site as well. If nothing else is uncovered, might be worth a query w/ the problem. Will be most interested to learn what you learn (as I'm sure, most other regulars will be, too)...

[Bewildered]

They can't imagine why I had problems, but told me to send the material to them and they will try to figure it out. \\\ Can;t beat that.

[George]

Resins are waterproof. They're also prone to migrate to the surface over time, as all who've had them bleed through a finish can testify. As indicated in my post, _might_ be a problem, even for wood given a thin pass over the jointer to freshen the edge.

Let me reiterate - this is speculation, just as the age of the glue and the temperature of the surroundings have been speculation. The makers of the glue properly caution against excessive clamping pressure, as this will compress the dampened fibers of softwoods like squeezing a sponge.