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Minimal science was involved, but the results are interesting anyway.

On a piece of plastic, I ran a bead of each of four glues I have on hand: Stew-Mac regular cure epoxy; Titebond II extend; GF glue from Lee Valley (same stuff available from Garrett Wade); and LMI white glue. I let 'em dry for three days.

Why those glues? Well, the epoxy for whatever; Titebond II extend for its longer open time, and for what I've read is improved hardness and creep resistance over original Titebond (but still reversible, with some effort); GF glue for general-purpose use (jigs, etc.) and for its slight gap-filling properties; and the LMI glue just to see if I'd like it (I've found its combination of ultra-slipperiness and fast tack to be hard to work with, but the final gluing results to be excellent).

Now, to the results. I wanted to see how they compared to each other in hardness (a good thing in lutherie), but I got an interesting surprise, too. The hardest, I suppose not unexpectedly, was the epoxy, followed by the LMI white, the Titebond II, and GF. The LMI glue didn't seem all that far behind the epoxy in hardness using my unscientific "thumnail" test, which I found impressive. I was suprised, though, when I popped them off the plastic and gave them a "bend" test. The epoxy didn't want to bend, and, after some effort, simply snapped apart. The GF glue remained very floppy--I could bend it into a circle. The Titebond II extend, though not too far behind the LMI glue in hardness, was just as floppy as the GF. To me, this would indicate a high potential for creep. Most surprising was the LMI glue--after giving a little, it snapped just like the epoxy! That glassy resistance to puncture and creep is exactly what LMI claims in their literature, which makes me want to believe their other promises of durability and easy reversibility. Quite impressive. I think I'm gonna have to reconsider not using it because of its short open time.

I know this isn't the definitive glue test, so I'd welcome any comments and observations.

Carlton,

Thanks for passing along the information. I have had very good luck with LMI glue, and your test just makes me feel all the better using it. I know some folks have had issues with the LMI, but I will continue using it. I do want to try hide glue on my next build, maybe you could throw that one into your next test.

Jeff

Hide glue and original Titebond rather that Titebond 2, please.

Colin

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

[QUOTE=Jeff Doty] Carlton,

I do want to try hide glue on my next build, maybe you could throw that one into your next test.

Jeff

[/QUOTE]

Jeff,

I'll probably try hide glue someday, but, being organizationally challenged, the preparation regimen makes it impractical for me to use at this point. What I need is a glue that has the lutherie-friendly properties of hide, but doesn't need the preparation. The LMI white is looking good in that respect.

[QUOTE=Colin S] Hide glue and original Titebond rather that Titebond 2, please.

Colin[/QUOTE]

Colin,

I tested Titebond II extend because, according to the manufacturer, it has superior hardness to the original Titebond, and greater creep resistance than both the original and regular Titebond II, in addition to a longer open time. That may all be true, but my modest test is showing me that the LMI glue is the best of the PVA's for lutherie. It seems to have much of the advantages of hide glue, AND it's ready straight out of the bottle--which, for my disorganized self, is a big plus.

    The test you did was for hardness not holding strength. Here is where things will change to a degree. I do agree the hardness is one of the factors but not the only one.
     Some glues will work better for one application than another. Edge to face glueing or plastic to wood etc. hide glue is okay and is pretty strong but you need to be willing to mix, heat and work the glue as requireded.
    Having used most of the glues you have mentioned I think a scientific test would be something worth doing. Also remember that harder glues may be a more efficient at sound wave medium. The other thing is that while harder , what is the yeild strenth as compared to the other glues and what is the shock resistance.
   Many things we need to consider.
john hall

John,

You're correct. Holding strength was never a part of my concept in this case. I just wanted to compare the glues from a different-than-usual angle. Besides, I've never heard of any premium PVA glue that isn't strong enough to hold a guitar together. It's the many other properties such as hardness, creep, reversibility, resistance to moisture and heat (up to a point), etc., of special interest to luthiers, that I'm seeking. Hide glue has the goods, but I just don't have the time, space, equipment, or will to deal with it--so I need sompthin' that squirts from a bottle. It looks like the LMI white is it.

I did a test about three-four years ago of side tapes. I used two kinds of tape (nylon and cotton-poly)and glued them across the grain to standard size pieces of wood using two kinds of glue; Titebond original (henceforth T-1) and hide glue. Then I broke the strips on a test rig that allowed me to measure how much force was required.

One thing that I found was that hide glue was measureably stronger in that application than T-1. In some cases the wood broke when the T-1 allowed the tape to come loose from it, while the hide glue held until the tape itself broke. This may be a function of creep; it's hard to say. I still have all the data, and I suppose I should publish at some point. I did put it out on MIMF at the time.

BTW, the nylon tape itself was much stronger than the cotton-poly, but it glued down so poorly that those samples tended to fail at much lower loads. The nylon tape almost never broke, it just popped off. The cotton-poly tapes approximately doubled the force it took to break the strips of 2mm thick side stock.

Simple science, and maybe not exactly what we're trying to find out, but more data...

Alan,

Interesting test of both tape and glue. Looks like hide glue wins again. If you happen to have some on hand, it could be mighty instructive to compare LMI white with the hide glue, using some of that cotton-poly tape. In any case, thanks for the information.