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I have a particularly nasty headstock break on my bench that was previously repaired. It's pretty contaminated so I really need to clean out what I can and use epoxy to glue it all back together. Any suggestions on a brand/type?

Well, for one - don't use epoxy. Whoever gets to fix that years later will curse you.

Clean up all the fibers with a toothbrush and a sharp Exacto blade until the all the fingers of the break knit together. Then glue it up with Titebond, clamp securely - pegheads breaks are tricky. Clean up the glue after 24 hours dry time, and touch up the finish. Get the instrument playing again, charge accordingly, and receive the acclaim so richly deserved by a competent repairman.

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"Act your age, not your shoe size" - Prince

Thanks Chris. I think what got me going down the epoxy route was the fact that I'll be using a backstrap overlay after it's all back together. The overlay I was planning on using titebond for so it wouldn't be epoxied to death lol

I'll see what I can do, it's been broken and reglued so many times that it'll take some doing.

Take your time, and get all the bent and broken fibers either lined back up or simply removed. It's worth the effort because that keeps enough wood in the break to allow a tight fit when clamped up. I didn't spline it as an experiment to see how strong it was. Worked fine, and I'll never spline a crack again.

Check this repair I did about a year ago on a broken bass peghead....
viewtopic.php?f=10137&t=52846&p=694314&hilit=peavey#p694314

I've done some bad ones... Back in the 80's a client brought in an all wenge Warwick with a broken peghead. His pal tried to fix it with a hot glue gun! It opened back up when he brought it up to pitch. Not only did I have to straighten out the bent fibers, but I had to pick out all the hot glue. That was a pain - but it came out great. Charged extra to fix the previous "repair".

_________________
"Act your age, not your shoe size" - Prince

Some pictures would help. First, start by diagnosing the type of failure between the adhesive (the sticky stuff) and the adherend (what you want to glue together).

Is this:

- A cohesive failure (i.e., failure IN the glue line...usually due to a thick, weak glue line or trying to use a non-gap-filling glue where major gaps exist)?

- An adhesive failure (failure of the glue to bond well with the adherend)?

- A break that started in undisturbed wood, but then traveled along the grain to a old, weaker repair glue line?

- A break that started on the site of an old repair, but then took a turn through undisturbed wood?

Also worth determining the type of glue used for the repairs.

- Animal glues like hide and fish are drying glues, so are easy to clean out and reglue with more hide/fish, even with significant adhesive residue still left, but are poor gap-fillers and tend to hold onto end grain with about a tenth the enthusiasm as they do face grain.

- Epoxy, PVA, aliphatic resin, polyurethane, and the two-part glues like urea/formaldehyde (Weldwood) are all curing glues, so will contaminate the surfaces to be glue to whatever extent residue remains after cleaning. The utility of these adhesives is in unique characteristics such as the ability to hold onto contaminated surfaces or to fill gaps, so they certainly belong in the mix for repair work.

When I was working with the guys on a routine basis, we saw a number of guitars with multiple neck repair failures from other shops or done by the owner...usually just one type of glue used, but a few with a mix' n' match thing going on...not unusual to see a failed Titebond repair followed by an epoxy or PU attempt, where the repair person somehow confused the ultimate strength of the adhesive with the the final strength of the repaired joint.

So do some research and come back...different types of failures and prior adhesives generate different strategies. Some repeat breaks will continue to happen due to poor stock selection or poor design (as Gibsons and Epiphones seem to demonstrate on a too-frequent basis)...no glue selection will make much of a difference in a short-grained, highly loaded area of the neck like the peghead/neck shaft transition, where a structural mod may be required to address the underlying material or design problem.

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Here's the rundown on this one.

Guitar is a Gibson acoustic, and the owner previously sent it to Gibson to have them fix the first headstock break. He got it back, it broke again in a different spot than the repair they did. He had it glued up again and it cracked again on yet another point.

In investigating it the grain runout on the neck is abysmal, the glue ups were solid as there are not visible glue surfaces and all the broken surfaces are bare open wood. I can see the multiple break lines in the finish on the side of the neck.

So that was the primary reason I was asking about the epoxy plus a good long overlay. The runout being that bad I don't really feel like appropriate gluing is going to get it done. The overlay is the real long term part of this fix. The epoxy was in the consideration to provide a stronger mechanical bond since there's all the previous break points in the wood, but going with Chris's advice I'll probably just use titebond.

Sounds like you have a good plan. FWIW for the first several guitars I built I used Epoxy to make the scarf joint. It's not a joint you ever want to disassemble so I don't see the need to use a glue like HHG or TB... Many luthiers for example use epoxy to glue the fret board though arguably you might want to remove that some day so I would never don't use epoxy there. but some do and they have their reasons, so do I for not.

I recently repaired the bridge plate that was previously terribly repaired by someone else who knows how long ago. There were so many chunks of top wood missing that I had no choice but to use a gap filling epoxy. And before the repair Nazi's flame in, it's a technique that repair guru Frank Ford has on his website too.

There are legit reasons for using epoxy and a smashed up scarf joint imho is one of them. Sometimes it's a last ditch effort and I've been around long enough to know that it will last when done right. Still though it's almost always a last resort but in joints that should be made to NEVER be dissembled then it's a good consideration.

Oh and Smiths stuff is pretty good. Smiths Oak and Teak is a good epoxy for such a repair.

I have stated here several times that this reputation of epoxy being impossible to separate with heat is untrue. It comes apart probably easier and more cleanly than Titebond. Just get it up to 200 degrees and it will separate cleanly. Of course, there are probably some epoxys that are more heat resistant, but I know that West Systems is one of the easy ones.

Of course it comes apart. Almost every glue a luthier uses comes apart around 200 degrees. But it's a solid gold PITA to clean out of a break.

_________________
"Act your age, not your shoe size" - Prince

All that being said, I think I'll talk it over with the client. Might be worth just saying that if it breaks again in the future it just needs a new neck, one without serious grain runout on the weakest part of the neck.

Thanks for all your input everyone