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Yesterday the stacked heel joint on my latest build popped off under string pressure. The joint was glued up at the end of November using LMI glue (is there a trend here ...?) and the neck had been on the guitar/bouzouki under normal string tension for a couple of weeks before it popped. I had good squeeze out on the joint and it was done in a warm workshop at 45 degrees humidity. It could be I clamped too hard as the separation is clean and I can't see much trace of glue residue on either face - only at the outside edge, also I may not have left the clamps on long enough:



I am going to reglue but am biting the bullet and am preparing some hide glue from the granules I bought from LMI -first time use for me. I am going to follow Frank's recipie on the factsheet and his website, leaving it in the fridge overnight and then preparing some glue from the gelatine slab (with some scrap wood testing first of course!!).

My question to you hhg experts is what should I do to the surfaces of the joint? At present there is some very slight tearout of mahogany on the heel stack from the top neck piece, but the joint fits pretty perfectly with these, and as I say there appears to be clean wood elsewhere on both surfaces. Should I just join as is with the hhg, or sand the surfaces first after filling the missing mahogany with some slivers?

Also, the LMI instructions say not to use sterated sandpaper. I use 3M Tri-M-ite sandpaper - is this sterated or non-sterated sandpaper?

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Dave, by the looks of the failed joint, there appears to be VERY little glue on it. So I'm thinking you either starved the joint by not putting enough glue on, or starved it with too much clamping pressure. The joint between to peices of wood using poly glues, is almost always stronger than the wood surounding it. So in a failure of a good joint, the wood would be all torn out and ugly.
I'm far from an expert on HHG. I've had very little success using it. But my instinct says to rejoin it just the way it is. Mate the torn out areas back together and they will make a great joint. If you go in and start sanding, you'll just have voids to fill.
Good luck. Paul

Most glues don't stick too well to cured PVA or aliphatic glues, including PVA and aliphatic. You should remove all of the glue from the surfaces if you want the strongest joint. Sadly you can't just wash that stuff off the way you could with hide glue: you will have to take off some wood.

Planed surfaces glue best, followed by scraped, with sanded surfaces a distant third. However you prepare the surface it should be done just before you glue it. The longer it sits the lower the 'surface energy' and the less strongly it will bond to the glue. Gluing within 15 minutes of working the surfaces gives the best joint strength.

There does seem to be a common thread emerging from these posts concerning LMI white glue: maybe they did get a bad batch.

Paul,

I don't think it was too little glue as these pictures show - it could have been all squeezed out through overclamping though:




Alan,

Are you saying that even though I can see/feel very little if any glue residue on the surfaces, it will still be there and weaken an hhg joint done on the surface as is? Ashamedly I have to admit that the surfaces were sanded not planed or scraped

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

I just had a beautiful WRC top seam fail with the LMI white glue. I thought that it might have been not enough glue, but now I don't know. And it was a costly failure since it had all of the purfling, abalone and bracing finished.

I can't believe that all these different people did something "wrong" enough to warrant a "glue -failure".
I'm sure I have "overclamped" joints and "underclamped" joints over the years,yet no glue failures that I know of using Titebond original exclusively.
The whole thing seems odd to me.
I have nevr used LMI's white glue though....

Hi Dave

I use ordinary titebond 1 for most things and I haven't had any problems.

I suspect with your joint there that as you suspect it maybe that you overclamp, G Clamps can apply alot pressure without you realising it.

Have you tried any Cam Clamps I find them much more controlable.

No that I'm any sort of expert on Glues

With all that squeeze-out, there had to be _some_ glue in the joint when you started, and some of that had to stay behind. I bet there's at least a moelcule layer on the surfaces, and 'close' only counts with horseshoes, hand grenades and nukes....

'Surface energy' was something I read about in an article on assembling fiberglass airplanes. It sounds 'New Age' but it's not. When you work a surface, planing or sanding or whatever, you are breaking chemical bonds. 'Weak' ones, mostly, but they are the things that hold stuff together, after all. When you break these bonds the busted ends 'want' to get back together, or, failing that, to find something else to bond onto. Over time they will lock onto whatever comes along: gasses in the air, water vapor, chemicals, pepperoni grease....

You, of course, would like those 'loose ends' to link up with your glue, and the way to get that to happen is to present the surface with the glue as soon after working it as you can, before something else gets there. The Forest Products lab found, in looking at aircraft structures in WW II, that you have about 15 minutes for this; joints made within that time were noticably stronger.

So the 'surface energy' is just a measure of the number of 'loose ends' there are to bond to. This, rather than 'toothing', is the reason why you sand fiberglass parts before bonding them. The article, in an Experimenal Aircraft Associaton magazine, said that one good way of testing 'surface energy' is to spritz a little water on the surface. If it beads up the energy is low, but if it spreads out into a film the energy is high. Makes sense: water molecules are polar, and are always looking for something to stick to.    

I have never had a serious problem with LMI white... I have heard these claims before though.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

[QUOTE=Brad Goodman] I can't believe that all these different people did something "wrong" enough to warrant a "glue -failure".
I'm sure I have "overclamped" joints and "underclamped" joints over the years,yet no glue failures that I know of using Titebond original exclusively.
The whole thing seems odd to me.
I have nevr used LMI's white glue though.... [/QUOTE]

Brad, I hope that you were knocking on wood as you wrote those words!

Steve

Dave...

Your glue up looks fine, some of the glue HAD to soak into the wood and that's about the amount of squeeze out that I get.

One question...

Is the glue residue powdery at all?? if you rub your finger over it does it come off??

The reason I ask is that it could have been a batch of old glue, I had one fail that I left in the shop and it got cold (last time I do that).

Also smell the bottle of glue (ok no jokes here), it should smell sweet and clean.

I'm switching back to good old titebond when the shop is back, I just seen too many people have problems like this and I don't want to temp fate...

Cheers

-Paul-

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-Paul-

Patriot Guitars

I had used LMI for years without a bridge/neck/repair failure. I switched to Titebond 1 about 6 months ago as somebody whose opinion I valued suggested it. At this point I don't remember who told me to switch but I have had nothing but good results with Titebond.
Evan

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http://www.NewYorkGuitarRepair.com

Dave,

I just don't by that you over clamped an area that large. I have glued up a mess of wood over twenty five years of woodworking and have never had a joint fail and I have clamp some stuff aweful hard (Iknow, I am tapping all over all kinds of wood...)! After seeing all of the post lately I absolutley suspect the glue. Although LMI is California where it likely won't freeze, the question is where is it it made and when was it shipped? Could it have been affected then? Also, PVA's and AR's do have a self life, although I have PVA that is few years old and should be tossed it is stil working well. If I was glueing that joint, my clamps and set up would look no different than yours, PVA and AR don't gap fill, you need good contact too loose and it pop!

Good Luck.......I wold turf that bottle of glue...

Shane

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Canada

Russell,

Until last year I used Titebond too. It was after reading on - I think - the AG Luthiers forum postings by people like Rick Turner that the LMI was a better guitar making glue, that I switched. I like it's grip properties better than Titebond which can slither all over the place for me, Also it cleans up better. No I haven't tried cam clamps.

Paul,

No the glue residue wasn't powdery at all.

Alan,

Point taken, I will scrape down to new surfaces just prior to glueing with hhg.

Shane,

I was aware of the short shelf life of LMI and get a new bottle from them every 3 months or so. That bottle was near the end for that joint and has gone now. Who knows what temperature fluctuations it was subject to in the air transport to the UK, but presumably the same is true fro Titebond on sale over here. The rest of the guitar-bouzouki was glued up with it and I have had no other problems with other joints. I now test some of the glue on a scrap to see that it dries clear.

Thanks for all your responses. I suspect it was something I did in the joint preparation, but the surfaces had a very good mating as I recall.

If any of the LMI people are reading these posts, a vote of confidence in the product would be very welcome

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

I had a perfectly planed joint open up on me once using the LMI glue, and I'd seen others claim the same problem on the MIMF. I'm currently giving it a second chance though for some things and not having any problems yet.

But I am weary of it, and this thread isn't much help for that!

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Instagram: @jfrenchluthier
Web: https://www.jfrenchguitars.com/

I had a ziricote back I tried to glue on a rim a year or so ago. I used LMI glue on it and did everything as I normally do. I glued it on. The next day it just popped off when I started to rout binding. I figured I must have done something wrong so I took it off, cleaned it all up, and reglued it. Popped off again the next day. I glued it one again with LMI glue. And for the third time it popped off again. I then, the 4th time, used titebond....it stayed on. I do however like lmi glue as it dries very hard and not as elastic as titebond, but I'm still wry of it (that said I used some today for a fretboard glue), but for everything I can now I use HHG. I'm really liking it...excpet for the smell.

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John Mayes
http://www.mayesluthier.com

   I've had a failure with the LMI glue on a tail block to top joint. I re-glued using the yellow stuff. It didn't come off after that.
   I know the LMI white glue dries harder, but I'll only use it on softwood to softwood joint (braces for top).
   I find the yellow stuff a lot thicker than the white (this might acount for the lubricating action) and I think this helps keeping more of it in the joint, even if clamped very hard.

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

HHG will not bond over other glues nor will it fill any voids or gaps. The joint must be tight and accurate.

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tim...
http://www.mcknightguitars.com

Tim, I'm probably wrong here but I was under the impression HHG had pretty good gap filling properties. Similar to epoxy. Am I wrong?

Very wrong, Paul. No gaps....

   250 or so guitars built and hundreds of repairs done with LMI white glue and not a single failure to date. It is a far superior glue for lutherie than Titebond, in my opinon. It's set tme is much more suited to eliminating sliding and movement during the clamp and it dries much harder. I used Titebond exclusively on nearly 200 guitar builds and all repairs prior to my switch at the suggestion of a close friend who is a great builder. I never looked back and always have a gallon or two of the LMI glue in my shop.

   With any glue you do have to be careful when it is shipped via ground where it can sit in a freezing warehouse or distribution center overnight on its way from sunny California. Once frozen, it should quickly make its way to either the trash can or into the kids' craft supply box.

   The photo indicates that the joint was pretty dry and the fact that the glue residue wasn't powdery to the touch on the surfaces after failing gives a pretty good indication that the glue was in good shape. I think many more people have had great success with the LMI glue than have experienced probems so I'd suspect the clamp pressure or joint surface preparation.

   That is a very small surface area to maintain integrity under string tension with the entire load being borne by the length of heel itself. I've never trusted a stacked heel and have repaired and replaced enough necks with them to keep me in the nonbelievers' camp on them. There's nothing like a one piece quartersawn neck or a laminated structure with the full strength of at least a few of the layers being allowed to provide full support along their heel by the one piece format.

Sorry to see it pop off on you, though,
Kevin Gallagher/Omega GuitarsKevin Gallagher38729.9934837963