Need advice on repair

[juneman]

Hey guys, this repair seemed like a easy fix. A couple clamps and it pulled it back together perfect. It seemed as if i had a good repair. Strung it up, played it for a week before i called the customer. He played it a couple weeks then it let loose. It still will fit back together perfect. Because it fit so easy,and was so easy to clamp and hold i used LMII new instrument glue. What are my options from here?

thanks Walter123140

[High Lonesome Valley]

I'm a "rough up the surfaces and use epoxy" guy. Never had one fail. I just make sure I score "X's" cross grain and don't extend the scores to the side-finished surfaces.

[multidon]

I have disagreed with HLV on this topic on other threads but I bet I'm not the only one who will tell you that you should first clean out all that old glue then re-glue with hot hide glue well clamped. The resulting joint should be very strong indeed. I also disagree with scoring the surfaces if you already have a nearly perfect match. Cross hatching would ruin that. Maybe that works for epoxy but it is better with hide glue to have the surfaces match. One thing I bet HLV and probably most others will agree with is that LMI was not a good choice for this job.

Hot hide glue is recommended for this kind of repair by Dan Erlewine and Frank Ford although Frank will use Titebond under some circumstances. There are articles on exactly this type of repair both on Frets.com and in Trade Secrets Archive on the Stew Mac site. It is amazing how much free information is available from just those two sites on a variety of repair topics.

Some reinforce the joint with biscuits but neither of the above recommend that.

[Shelagh Moore]

I have just such a repair coming onto the bench imminently (a Gibson guitar) and will use hot hide glue and firm clamping just as described above by Don with no scoring or other interference with what I see to be perfectly mating surfaces. I expect to achieve a very strong repair.

[Folkmusician.com]

I get a lot of this exact repair from our shipping damage. If it is a crack as pictured (that hasn't already been glued), hot hide glue does the trick. No scoring. How to proceed after using the LMII glue depends on how well you can clean off the old glue. Doing so without compromising your perfect fit can be difficult. I would fully agree with Don as long as you can get all of the old glue off.

[billhay4]

Ignore HLV's advice, please. This kind of repair needs to be easily re-doable, yet strong, and not destroy the value of the instrument. If it's a banger, go ahead.
Bill

[Nevin]

I have done a few of these. My aproach would depend on the kind of glue you used before. If it was hide glue than I would go with hide glue. If it were any other kind of glue, unless you are sure you can clean all of it out, I would not use hide glue. I have had good luck using thin CA (super glue) when there is a previous repair.

[mirwa]

If it's been glued once and has failed again at the same location, then spline it, so it's stronger than when the manufacturer made it, as a side note, if it glued up really easy, why the bursting of the area

[Andy Miller]

One thing I bet HLV and probably most others will agree with is that LMI was not a good choice for this job.



Multidon, What do you think makes LMI glue a poor choice for such a repair? I would have thought it's as good a candidate as Titebond, am I mistaken?

[Dale Ludewig]

I probably would have used HHG but I don't see anything inherently bad about using the LMI glue. As to cleaning it up now, this is a remarkable product. I think it's basically acetic acid in a glycerin base (I could be wrong):

http://www.stewmac.com/Materials_and_Supplies/Glues_and_Adhesives/Glues/Wood_Glues/De-Glue_Goo.html

[Andy Miller]

If it's been glued once and has failed again at the same location, then spline it

Whatever the cause of the failure, I would agree it's now time for a trip to Spline Town. Unless you're talking about exposed, flat glue surfaces, cleaning off all the old glue to expose a clean, tight, well-aligned glue joint is virtually impossible. The failure of the first repair indicates that maybe the break is just a little too steep for a reglue-only, and any reglue you do from here is likely to have less integrity than the first reglue. I would clean it up as best I could, glue it up with epoxy since it will do better with the inevitable traces of old glue and gaps resulting from cleanup, and proceed with a spline repair from there.

[billhay4]

Stewmac (https://www.youtube.com/watch?v=6DwA56TKWq8#t=134) just published a video on just this topic.
Hope it helps.
Bill

[multidon]

Well I have to admit that I have not used the LMI glue but when I made that statement I was thinking about the white formula. That glue while reportedly good when fresh had a notoriously short shelf life of only about a year as they themselves noted on their web site, and I quote, "as a general rule of thumb,if it smells sour, use it as a household glue but not on instruments". Also there were other complaints about it such as it clogged sandpaper quickly. Not relevant in this case but still a shortcoming.

I don't check the LMI site often but I now see they apparently have replaced the white formula with a yellow one that looks more like Titebond. I have no idea whether the repair was done with the old white or the new yellow. If it was the old white it may have lost some bonding power.

That it was inadequate to the task is self evident. I bet if the original repair had been done with HHG it would have held. But that is of course sheer speculation on my part.

[Bill Snyder]

Don, even PVA glue like Titebond has a shelf life of a year or less for luthiery.
I don't have any experience with the LMI glue (old or new) but I recall Rick Turner singing its praises (the white stuff) a few years ago.


I wrote this a while back, and it's fairly up to date for me:

Glues I use in lutherie, where I use them, and a bit about why...(snip)

LMI white glue
Peghead scarf joint
Most assembly of semi-hollow guitar bodies

This glue (I believe it to be a polyvinyl acetate..PVA) has the convenience of Franklin Titebond and other “carpenters’ glues”, yet cures much harder and seems to have some of the favorable qualities of hot hide glue. It is known for low “cold creep”, a possible real factor with regard to tone and the need for neck resets on acoustic guitars.
...

[multidon]

Just for the record, according to LMI, they discontinued the white glue because their supplier stopped making it. And they also claim their new glue is different from, and superior to Titebond even though it looks similar. And they say it is an improvement over the white product too. On the web site they list the specific ways in which it is an improvement over the old product.

Bill makes a good point about shelf life for all glues. But it seems to me from my experience limited though it is that the holding power of Titebond degrades pretty slowly while some other glues go bad more dramatically. CA seems to me to be one of those that goes from super to wimpy pretty quickly. I don't know but is it possible that the LMI white is one of the dramatic ones?

Interesting that Dan Erlewine chose bottled hide for his repair in the new video. This is a product almost universally panned here. But he did a test glue on scrap first to make sure it would hold. Maybe this would be a good standard procedure before glueing any repair that will be subjected to stress.

[testore]

However, now that hide glue was not used the first time it will not stick as well to a non hide glued joint. If you use hide glue for the second time I would try to wash as much of the old glue out with hot water first.

[HoGo]

However, now that hide glue was not used the first time it will not stick as well to a non hide glued joint. If you use hide glue for the second time I would try to wash as much of the old glue out with hot water first.
I'd say if regardless of what you plan to use you need to clean the old glue residue. Not much will stick to dried PVA and even if it sticks reasonably well (like CA) you will have sandwich of wood/old PVA/new glue/old PVA/wood that may fail at any of the four "/" signs.
Use acetic acid (vinegar) on q-tips or similar gentle tool, perhaps slightly heated, to remove glue from wood and wash away old PVA, do it slowly try to get into tight spaces, be carefull not to wet too much surfaces around finish and do final cleaning with distilled or deionized water. Let it dry completely for few days and I'd lightly clamp it together while still wet for few hours so the wood fibers won't swell too much and you lose good joint. You may notice some sticking together which is sign that there is still some old glue to clean up.
Then follow with good old HHG.

[Rick Lindstrom]

Did your customer by chance leave the instrument in a hot automobile?

BTW- some of the worst repair nightmares I've encountered involved redoing "repairs" executed by well meaning people who used epoxy.

[testore]

What Adrian said is absolutely correct. I wasn't sure of the composition of the LMI glue.

[High Lonesome Valley]

BTW- some of the worst repair nightmares I've encountered involved redoing "repairs" executed by well meaning people who used epoxy.

However, now that hide glue was not used the first time it will not stick as well to a non hide glued joint. If you use hide glue for the second time I would try to wash as much of the old glue out with hot water first.

My apologies for not qualifying like glue for a really valuable piece, I assumed because of the satin finish otherwise.

"Well meaning" doesn't guarantee the quality of a repair with hide glue, PVA, CA, epoxy, or bubble gum. One of the reasons I score and then use epoxy, it's never resulted in failure, although some of the other techniques mentioned here have failed for me. The scoring process also scrapes the old glue off and exposes new unglued wood, that's assumed by anyone who is familiar with scoring. Getting the old glue off with hot water and chemically, whether the manufacturer's original or the second glue job, opens up an issue with possible wood swelling, which creates a whole other issue of having to sand down and totally refinish the now non-approximated joint; also unequal swelling on surfaces can compromise those surfaces. Water and chemicals also seem to seek out just under the finish to swell the wood and even peel up the edge of the finish. Now a simple one-hour-or-less repair possibly becomes a nightmare that needs to visited for at least several hours. Been there, done that, learned the lesson.

To score or not to score, which glue to use, seems to be an oft visited and heated ideological discussion from my brief time here on MC. I don't see anything wrong with if it works and doesn't harm the instrument, and the several vociferous responses seem to ignore the "it works for me" factor. I think the only real judgment call on this repair, esp. on a valuable instrument, is whether the repair that works for all of us after our own fashion, would impact the intrinsic value more negatively or not. Otherwise, we're getting into the Hatfields and McCoys.

What works? Yours, mine, and his. They all work, and each of us is comfortable with our experienced approach to get an instrument playable again, which was highlighted by Erliwine's use of bottled hide glue, anathema to many here.

The point to this repair, when all is said and done, is "what works". Juneman followed the standard course that we've all done, and it failed. Now, how best to follow up.

[juneman]

Hey guys, first thanks for all the responses. The glue i used was from a fresh bottle of the new LMII instrument glue. I always test first any new glue or when i am gluing any oily wood like coccbolo. The glue looks alot like Tightbond,maybe just slightly yellower in color. The mando is a Jbovier. It got knocked off a stand and fell off a stage. It was a clean break,fit together perfect. When i glued and clamped it, cleaned up the squeeze out it was almost in visible. Still at this point, i am not quite sure my course of action for the repair. Hot water and vinegar and a careful cleaning should get the surfaces back to their original condition. Both sides still match up perfect. Keep the advice coming and thanks again.

walter

[multidon]

Now that we know exactly what kind of glue was used, that it was fresh and tested, it is difficult to understand what caused the failure. LMI claims their new yellow glue is better than their old white and better than Titebond, in their own words. If true the joint should not have failed. If the instrument was left in a hot car the rest of it would be falling apart too. LMI claims their glue fails at 190 degrees. Titebond fails at 142 degrees according to Stew Mac.

Epoxy use is becoming more common in instrument making. I own a Martin guitar with a Richlite (micarta) fingerboard and bridge. They have to use epoxy because wood glues do not stick well to micarta. Also I understand epoxy may be necessary for oily woods like coco bolo.

I still think HHG is the way to go but only if every scrap of old glue could be removed. If you can't be sure, maybe HLV is correct and it's time to break out the epoxy. Good quality stuff, not hardware store stuff.

[Rick Lindstrom]

My apologies for not qualifying like glue for a really valuable piece, I assumed because of the satin finish otherwise.

"Well meaning" doesn't guarantee the quality of a repair with hide glue, PVA, CA, epoxy, or bubble gum. (Edited for the sake of brevity, not to take anything out of context. The original post is still in the thread for reference if necessary)

"Well meaning" in the sense that a person who uses epoxy to do instrument repairs may not realize the problems epoxy can cause should the repair ever need to be redone, or undone for that matter. Most of the glues we use in luthiery are "reversible", some easily, and some harder, and can be effectively cleaned out of a repair, if necessary. Not so with epoxy. I know this from having to undo and redo repairs done incorrectly with epoxy.

Using epoxy on instruments is risky business. If you trust your technique and don't ever expect to have to go behind yourself and do it over, fine. On the other hand, if you use epoxy, you may be setting yourself, or another luthier, up for some big fun at a future time getting it back apart again and redoing the repair.

Just sayin....

Disclaimer- I have used epoxy on instruments before, but only when doing fingerboard inlay work to set the inlays. Using epoxy is legitimate, and accepted, in this application.

[Jeff Mando]

I worked at a busy repair department at a vintage guitar shop and fixed hundreds of headstock repairs with Titebond--never had one fail. FWIW.

Re-repairing somebody else's failed repair is always a challenge, but basically remove all the glue you can and do it again.

Epoxy I treat as a last resort "solution". An example would be an inexpensive guitar that has been broken for the THIRD time at the peghead and there is little to work with. A favorite guitar that the customer refuses to throw in the trash. With that said, the customer needs to be aware of the repair and not go banging it into doorways, etc., or it will break again.....

[Jim Adwell]

Acetone and heat will remove hardened epoxy on wood. It's not fun or easy to do, though, and I would not recommend trying it, especially on a musical instrument.

Epoxy bonds are not as strong as hide glue or PVA glue (or CA, for that matter). The only reason to use it on wood AFAIK is to strengthen weak rotted wood in antique furniture rather than replacing parts, or as a last resort, perhaps. And of course gluing carbon fiber to wood. :)

[Pete Jenner]

Acetone and heat will remove hardened epoxy on wood. It's not fun or easy to do, though, and I would not recommend trying it, especially on a musical instrument.

Epoxy bonds are not as strong as hide glue or PVA glue (or CA, for that matter). The only reason to use it on wood AFAIK is to strengthen weak rotted wood in antique furniture rather than replacing parts, or as a last resort, perhaps. And of course gluing carbon fiber to wood. :)

...and it can fill gaps.

[Jim Adwell]

...and it can fill gaps.

Yup. Although you really need to use a filler of some kind for gaps big enough to require epoxy. I've used wood dust as a filler on the rare occasions I've needed to use epoxy to fill gaps in a poorly fitting joint in wood.

[Andy Miller]

I worked at a busy repair department at a vintage guitar shop and fixed hundreds of headstock repairs with Titebond--never had one fail. FWIW.

Re-repairing somebody else's failed repair is always a challenge, but basically remove all the glue you can and do it again.

Epoxy I treat as a last resort "solution". An example would be an inexpensive guitar that has been broken for the THIRD time at the peghead and there is little to work with. A favorite guitar that the customer refuses to throw in the trash. With that said, the customer needs to be aware of the repair and not go banging it into doorways, etc., or it will break again.....

Titebond is the go-to for most repairs where I work. Basically with headstock repairs, if it doesn't look like something I would trust Titebond for, I look to other measures such as a spline repair. Maybe I should consider hide glue in borderline cases where the break is uncontaminated. It might allow me to pull off some things I'd normally relegate to splines and extensive touchup work.

I use hide glue for some things, definitely where it seems historically correct, but the fact is we don't keep a pot heated up at all times, so if Titebond gets the job done well, Titebond is in a bottle next to my bench and Titebond it is. I like hide glue, it's got some great qualities. If it were available for me to choose over Titebond at any moment, I'd choose it often. But it's not, and when I have four guitars in the spray booth and four by my bench and twenty I haven't started yet, I'm not going to break out a double boiler rig and take up that time and space unless the repair really demands it.

Epoxy. . . well, I don't use it very often, the reasons already being mentioned by others. Believe me, I've suffered through my fair share of reworking the poor repair choices of others who came before me. For that matter, I've suffered through my fair share of repairing instruments that were put together with repair-unfriendly materials and methods to begin with. But if it's a failed headstock repair that I'm going to spline anyway, I really don't care about reversibility of the glue in the original break at that point - permanent is fine.

[High Lonesome Valley]

Epoxy. . . well, I don't use it very often, the reasons already being mentioned by others. Believe me, I've suffered through my fair share of reworking the poor repair choices of others who came before me. For that matter, I've suffered through my fair share of repairing instruments that were put together with repair-unfriendly materials and methods to begin with.

This is a non sequitur to support your unwarranted opposition to the use of epoxy.

When an unwitting owner does a lousy repair from start to end, why blame the glue? Epoxy is used because it's a very strong bonding and structural filling agent, the owner has that much right, but the classic misrepair is epoxy slathered on the OUTSIDE of the headstock break, never clamped, headstock misaligned. And also the ever-present wood screw.

This is no fault of the glue or the screw.

[testore]

I understand your point of view, and it is a good argument. However, ALL repair work needs to be redone at some point. The idea is that you MUST use a glue that can be easily cleaned off and the repair redone. This is why violins that are 300-400 years old are still being used today. That makes ANY use of a screw unwanted. To make a hole in an instrument to house a screw only adds to the damage and the eventual redoing of the repair. This is, at least, what I've experienced in the last 30 years of doing this.

[juneman]

Hi everyone, as most of you know some may not. I am mostly a builder with repair work a smaller but growing portion of my business. Having used Tightbond and LMII original glue extensively over the last 12 plus years i never expected the joint to fail. It fit so perfect,so easy to clamp i thought it was a no brainer. So it does baffle me why it failed. My initial repair separated perfectly on the glue line.It fits back together perfect. I could have used HHG but for what ever reason did not. My two current projects on the bench are two guitars that i have used the new version of the LMII instrument glue. I tested the glue when i got before i glued up the cocobolo dreadnaught. It worked fine,so like i said i am a little perplexed as to why it failed. I know the customer so i have no reason to doubt when he said he found it in the case that way after playing it for about a month. So far i am leaning toward a good cleaning of the joint ,ample dry out time and HHG. Just food for thought. Something i did notice was squeeze out in the truss rod pocket bottom. Could i have clamped and squeezed out to much glue leaving too little for proper adhesion. The new glue does have a different consistency from the older. Just a thought?

thanks Walter "JUNE" mandolins and guitars

[Pete Jenner]

Maybe the customer left it in their car on a hot day Walter.

[Jim Adwell]

When you say it failed on the glue line, do you mean there is glue on both parts, or is there some raw wood on one piece? Are you sure it's not a wood failure?

Just checking off possibilities here.

[fscotte]

Carbon fiber rod + epoxy. It's won't budge.

The CF is made up by using epoxy glue. Essentially if you can drill out a space for the rod then glue with epoxy, the cf rod will hold the neck by itself. They are strong as steel.

[juneman]

hey Jim,the peghead over lay and binding are holding the peghead on. The wood just looks too clean almost like i never repaired it, and its on the exact original break line. The strange part is it looks like raw wood,like there is not much to clean up. Even though i will give it a good brush cleaning and ample dry time before i do a re-repair. Here are some pics but the may not show enough detail.

walter123260123261123262

[Jim Adwell]

Hard to tell from the pics, but it looks like the wood failed near the glue line, because it sure looks like there's no glue there.. Or there wasn't enough glue. If the wood is indeed weak there, epoxy might be a good bet for a repair as it will soak into the wood around the joint and strengthen it. But I can't really tell without seeing it in person (maybe not even then).

Things like this are why I never got into the instrument repair business. ;)

[Rick Lindstrom]

This is a non sequitur to support your unwarranted opposition to the use of epoxy.

When an unwitting owner does a lousy repair from start to end, why blame the glue? Epoxy is used because it's a very strong bonding and structural filling agent, the owner has that much right, but the classic misrepair is epoxy slathered on the OUTSIDE of the headstock break, never clamped, headstock misaligned. And also the ever-present wood screw.

This is no fault of the glue or the screw.

So use epoxy if it seems right to you. You certainly shouldn't let the collective wisdom of the luthiers in this forum influence your thinking.

[fscotte]

I don't want to stress epoxy is best, just saying carbon fiber is strong as steel and epoxy is used to glue the sheets together.

Besides, I understand Derrington used a "special" epoxy to repair the slivers of wood on Monroe's mandolin. If this is fact, then there must have been a reason he didn't use HHG.

Ah here it is:

Derrington laboriously separated the wood splinters, using a pair of tweezers and a magnifying glass. He found that he was able to sort them by color, as the finishes on the two instruments were slightly different.

Using an acoustically transparent epoxy to glue the pieces in place, Derrington worked 40 hours a week for the next three months repairing the primary mandolin.

[Andrew Faltesek]

Ouch, just had to fail right at a difficult spot. Looking at the photos, I'm with some of the others and would do a very careful cleaning first; break out the lighted magnifier lamp, etc. and do as little harm as humanly possible. On this nice instrument I would go with freshly prepared Behlen B940-00255 ground hide glue, 50/50 with distilled water @ 145 deg. F, pre-warm parts with hot air. I'm not sure, but I think the gram strength would be 164 so you could have a very close-fitting thin glue line with very good strength.

Reinforcement with rods or splines, etc. is not out of the question, but installing them would probably cause more alignment problems and would complicate a hide glue bond, so that would be the Titebond or West System epoxy path. I vote epoxy no, CA no, Titebond maybe, hide glue yes. In other words, like tying knots...sometimes a simpler knot tied well is stronger than a complicated knot that pulls together imperfectly. Good luck!

[High Lonesome Valley]

I vote epoxy no, CA no, Titebond maybe, hide glue yes. In other words, like tying knots...sometimes a simpler knot tied well is stronger than a complicated knot that pulls together imperfectly. Good luck!

Thought this was a clean join break originally but see it's not in recent pics, Juneman. I retract my call to roughen surfaces as this is not a clean joint separation. Seems the too-deep tension bar slot might've been the destabilizing factor.

Attempt to remove old glue from surfaces, water, chemicals, whatever. Even if you don't see the glue there. Grit your teeth and realize you'll have to refinish the entire joint area. Make sure you get out ALL residual glue after clamping, even if there's a divot, then standard refinishing on the joint and surrounding area.

I would say no on CA because I've found it is too brittle. PVA failed, why repeat a failed attempt.? Both hide glue and epoxy have a sticky factor that PVA really lacks, just a little more PIA to push in, esp. under the headstock laminate. Both glues have thousands of pounds PSI strength, that's not an issue here.

This is more like a scarf joint, not a modified rabbet or dovetail, etc. with a built in key/lock and where I would feel more comfortable using hide glue. I personally would still use epoxy due to the scarf factor, it is by no means brittle as I've found a measure of with hide glue. This is taking into account probability of stressing the joint again with a fall or even, God forbid, a child bumping into it while leaned against the wall.

A spline previous to assembly does sound tricky. Perhaps, after initial gluing, imbedding two carbon spline wafers midline to either side of tension bar slot, covered with a thin piece of maple on the now outer surface slots and then oversprayed with black?

If the next repair fails again, this could become a parts mandolin or neck replacement, hence the more radical step of externally applied spline. Hope to avoid a complete loss and be willing to take an aesthetics hit on the top of the neck to save the mandolin.

[Andy Miller]

This is a non sequitur to support your unwarranted opposition to the use of epoxy.

HLV, you must have misunderstood me - I don't oppose the use of epoxy. In fact, I already stated that in order to re-do this failed headstock reglue, I'd probably glue it up with epoxy and spline it.

[Andy Miller]

The strange part is it looks like raw wood,like there is not much to clean up.

123260123261123262

Maybe the perfect way it fit back together, plus a lot of clamping pressure, just squeezed out too much glue, starving the joint. It happens more often with joints involving flat, easy-to-clamp surfaces like you find in cabinetmaking, but it can happen here too. This must be one of the reasons my boss always says "fixing instruments is hard."

[Jim Adwell]

It's pretty much impossible to starve a glue joint with clamp pressure. More likely by far is to not use enough pressure, producing a weak joint. Or not using enough glue in the first place.

[High Lonesome Valley]

HLV, you must have misunderstood me - I don't oppose the use of epoxy. In fact, I already stated that in order to re-do this failed headstock reglue, I'd probably glue it up with epoxy and spline it.

My sincere apologies.

After the horse wreck, my short term memory now consists of sticky notes.

[High Lonesome Valley]

It's pretty much impossible to starve a glue joint with clamp pressure. More likely by far is to not use enough pressure, producing a weak joint. Or not using enough glue in the first place.


Have seen quite a few dry glue joints responsible for separation, per Andy.