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What are my options for re-gluing this original bridge?? How should I go about it? Here are some picture:





I assume I need to remove the finish that the original builders missed on the top under the bridge, and remove any remaining old glue 9not much). I intend to leave some of the groves in the top instead of taking more top wood away. Do you agree this is best to leave?

If the top area needs to be routed to remove the grooves, how does one set up for this?
(The problem with routing out all ridges is thinning out the top as much as 2/64" when the top is about 7/64" thick at the sound hole. Also the top area at the bridge has a slight upward bellow in the rear and very slight dip in the front, all as would be expected in a guitar over 50 years old. I'm not sure how to, or even if you would want to, make this flat. Seems to me that it would need to be routed smooth, not flat. And the clamping of the bridge would make it flat when drying. How would I go about routing it? What size router and what kind of set up?)

Since HHG and Titebond will not work for filling voids (groves in top), what could I use to glue the bridge without routing the top that could be removed years later if needed?

Please help.

Thanks,
Ed

For gap filling repairs there is really only one choice - epoxy. Remove as much of the old glue as you can - try to get all of it. Put on plenty to fill those gaps.
Use a clamping system that allows you to clean the epoxy squeeze out before it hardens. I'd use 8-32 bolts through the bridge pun holes.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Thanks very much for the help, Steve. I was afraid that epoxy was the only choice for gap filling. Would you choose epoxy as the better method than routing the top down and using Titebond?

Thanks again,
Ed

Steve has given you good advise. If you have to bring down the top to compensated for the loss in soundboard fibers, you may create a weak area. Glue it down with epoxy and clamp tightly. Clean squeeze out around the bridge with a paper rag and alcohol. Don't have to use too much glue but do make sure to clean it before the glue dries like Steve recommended.

Good luck.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Thanks, Peter.

Yes, I was concerned about routing making the top too thin under the bridge. Right now it has the vast majority of the original top material. Just the few grooves mainly on the two wings creating a problem.

What is a "paper rag"? A paper towel? I would have used a soft cotton rag. Does it make a difference?

Will alcohol affect the old nitro finish around the bridge? There is only about 1/32" between the bridge edge and edge of existing finish.

Should I do the finish touch up first to close this 1/32" gap before I glue done the bridge so I can sand the finish touch-up smooth?

Thanks much for the help.

Ed

I meant a rag... could be anything. I'm not sure about nitro but I think its fine. You may want to test it in that area that's going to be covered by the bridge.
Why is there a gap around the bridge?

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

The gap is from two reasons. First, the front finish was scraped off about 1/16" by the bridge when the bridge moved forward.

Second, I carefully measured the scale length and the saddle, with the bridge in the original position, is setting so that the front edge of the saddle equals the distance from the nut to the saddle front for the full compensation. I think it best to cheat the saddle up the 1/32" so that it measures closer to the center of the saddle to allow for more leeway for intonation adjustments. With the full amount of compensation at the front of the saddle I could only make the strings longer by compensating the saddle. Is this a good reason? Also, the pins slant towards the endpin when the bridge is in the original position. Cheating up 1/32" allows the pins to go straight in (straight up and down). Or would you put the bridge in the original position? (this creates the need for finish touch up on the front and back of the bridge, whereas, if I put the bridge in the original position it would only be needed up front - but a larger strip up front)

Ed

Disclaimer: it is really tough to give any good advice without actually seeing the instrument in person.

It looks like the spruce is really no damaged too badly, i would not rout it, that just seems scary and too easy to mess up. I would just scrape any glue residue off, i use a sharp chisel for that, and then lightly block sand the area just to nice up the gluing surface a little.

I would use hot hide glue, or even titebond, i am not crazy about epoxy on soundboards, if/when the bridge ever needs to be reglued again the repair person will forever curse the name of whoever epoxied that thing on there.

I am not sure what is considered acceptable now, vintage value wise, but it used to be standard procedure to yank the bolts and toss them, they suck, and it is much easier to dress up the underside of the bridge without the bolts in the way.

Really, this is one i would need to have in hand to be comfortable giving advice on, so take what i say with that in mind.

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Jordan Aceto
Ithaca, NY

I would also advise avoiding epoxy for regluing the bridge, if at all possible.

Epoxy is a tone killer on the soundboard. and in the last 40 or so years of repairing guitars I have had to deal with bridges poorly glued with epoxy more than a few times. Epoxy has its place as far as guitar building and repairing, but not for glueing bridges. Take Jordans advice, as that's what I would do in this case, pending inspection of course. And if you really want to preserve the value of this instrument I suggest you take it to a qualified repair person if one is in your area.

My .02.

Cal

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Remember, there are no stupid questions, only stupid answers!

There you go - you want opinions you have them. Obviously, there is disagreement on this. I would avoid using epoxy on the bridge also, but under your conditions, as you described them, I see it as the best alternative. I've used epoxy on bridges and strongly disagree that it is a tone killer. Like any joint, if the process is poorly executed, it will have issues, including robing tone. That is true with any adhesive. There is nothing inherent in the properties of epoxy that make it a tone killer.

There is one fact that is not debatable. For gap filling, epoxy is the clear choice. No other glue handles gaps like epoxy.

If you can safely execute the joint without the gaps as you described, use any glue you want, as long as you can remove the old adhesive. Another advantage of epoxy is that it can grip other adhesives. No other glue does that. So if you can't clean up the old glue, that would be another reason to use epoxy.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

The top is definiately NOT badly damaged. There is plenty of wood there. But the bridge did take some slivers of the soft part of the top grain with it when it pulled loose of its own accord. The original builder, Gibson, just did a very poor job of preparing the surface for glue which is what caused this.

The bolts are an easy call. History has now shown that yanking the bolts hurts the vintage value of old Gibsons. (Note that I am making no comment about the sound quality, only vintage monetary value.) Therefore, the bolts need to remain even thou I agree that they are a problem to work around.

So now there are two recommendations for epoxy and two for glue. I originally thought glue since I want someone in the future to be able to be able to get the bridge off if needed. But however I glue it, it obviously needs to hold the bridge down (I'm not relying on bolts even though they are there.)

How should I prepare the bridge bottom for glue?

Are there any other very experienced repair luthiers that think titebond will hold it OK?

Ed

I scrape the glue and crud off with a chisel. If you scrape, be cautious around the holes, because if you scrape across them the scraper will want to create little valleys around the holes if you work with too much gusto.

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Jordan Aceto
Ithaca, NY

Hi,

I would also recommend hide glue for this repair. I would clean the bridge completely by scraping and/or sanding the residue spruce and glue trying to avoid removing any of the original bridge material. Scrape and remove as much of the old glue from the guitar top and avoid sanding or scraping across the grain. Once you’re happy with the dry fit apply the hide glue and clamp. If the surface is well prepared the glue up should last for years.

It looks like the original glue up may have been starved for glue as indicated by the clear front and side of the bridge. If you get a good fit you can count on another 50 years before needing another glue job.

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Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

Thanks again Steve,

Yes, I am getting different opinions, but I am learning from the discussion. Here are the things I know for sure:

1. The grooves in the top (due to the bridge taking top wood with it) range from ~1/64" to 2/64" deep. These grooves are mainly located on the wings/outside of the bridge footprint and can be seen in the pictures.

2. The groove bottoms are fresh wood with no glue in them. The top of the grooves have some glue residue on them (and a few small areas have original finish mistakenly not removed by Gibson overr 50 years ago)

3. The grooves in the top must either be:
a) filled with glue
or
b) removed by sanding or routing. (I will not route it since I do not have the tools or experience. I could sand them down, but I was and still am concerned about reducing the 7/64" top thickness by up 2/64".)

My gut continues to tell me to maintain as much top thickness as possible to avoid weakening this critical area. So very light sanding/scraping to prepare the groove tops for glue makes sense to me. But removing the grooves entirely will lower the bridge and weaken the area. So if I keep the grooves, they must be filled with something (glue) that will bond the top and bridge properly together.

I hear some people say HHG or Titebond will still work OK with the grooves, and some people say they will not because the surfaces are not smooth enough. I am eager to hear others' opinions on this since my hope was to use one of these glues (but mostly I want to make the best choice between this and epoxy given the situation)

There seems no doubt that epoxy will fill the grooves and give a proper bond, but the ability to remove the bridge at some future point is questioned by many. I am eager to hear others' opinions on this as well.

I could leave the original material on the bridge bottom to partially fill the gaps, or remove it to obtain a fresh gluing surface. There seems to be disagreement on this too. If I used epoxy, it appears leaving the existing material on bridge bottom would work just fine since epoxy will bind to it (combination of old glue and fresh top wood on the bridge bottom).

Before starting this topic, I had hoped that cleaning the bottom of the bridge to a fresh wood surface (scraping and very light sanding) and light scraping/sanding of the top (leaving the grooves) and bonding with Titebond would be the answer. Now I am leaning towards doing this as just stated except using epoxy for the bond. (But I really hate to use epoxy since it will make future repairs very difficult as I understand it.)

Who else out there wants to weigh in?

Thank you all for your opinions and help.

Ed

If you do use epoxy, there are all different grades and qualities. I once did a furniature repair and the epoxy I used did not bond to even a new, roughened wood surface. I cannot recommend an epoxy, but maybe others will chime in, if not already having done so.

I don't know where you live but if you are within a couple of hours of an experienced repair person, take the guitar there and trade lunch for an opinion backed up with experience. You can still do the work yourself. It will be time well spent. Jordan is 100% right. It's really difficult to give worthwhile advice on something like this without seeing the instrument. I'd do everything I could to avoid epoxy. Good luck.
TJK

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I stumbled on a web page a while back that I unfortunately forgot to save. This man demonstrated a method using spruce plane shavings and hide glue to fill voids with mini 'ply' layers. I tried it on an old bridge/top repair that had a chunk missing. Worked very well. Repair is clean. mostly reversible, and so far - so good. I wish could locate that page.... to give credit due.

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Tom Krebs

Oh the variables.....

This is a Gibby with a reverse belly bridge. It's about 50 years old, right, so that makes it a 60's vintage. I think they were using a synthetic glue then.

New glue of any kind won't stick properly to old Titebond or white glue. You need to get all of that glue off the bottom of the bridge, which means scraping it back to the wood. It's not that big a thing anyway: I'd bet that the bridge has distorted enough that you will need to re-shape that surface anyway to get it to fit the top properly.

The divots in the top can be dealt with in a number of ways. I would not recommend scraping or routing the top down to level that area out: it's probably thin enough as is. With a little patience you can fit and glue slivers of wood in to fill the areas where it it missing. This is easier than fitting a splice in the top where it will show, since you're not as worried about cosmetics. Believe it or not, filling those areas with some sort of wood dough might be better than nothing: a thick glue line might be weaker than a gap. I'd still tend to go with slivers of wood, though. You can use almost anything to glue them in: consider how well you can fit them, and how much clamping pressure you can get. Remember that HHG will pull in without clamps once it gels, so holding a sliver in place for a little bit works really well if it fits reasonably. CA would be another good choice.

Once you've got the gaps filled you can level the top surface off and use any kind of glue to put the bridge on. I tend to shy away from epoxy, partly because I only use it when nothing else will do, and partly because it's not 'standard practice'. The next guy who has to work on that bridge might not know it was epoxied, and could rip things up trying to get it loose.

Titebond would be in the spirit of the original, and if you fit it properly it will hold up at least as well as the original did. Probably better; they sometimes didn't do such a hot job....

HHG would be better, IMO, but if you don't know how to use it it might not be a good idea to learn on such a citical joint.

Touch-ups are the worst part of any repair. At least the original finish was clear, so color matching will not be quite such a drag. Use nitro, obviously.

I hate bridge bolts. They are a good example of something that Jim D'Aquisto said once: "If people do something WRONG enough for LONG enough, it becomes right". Gibson did a lot of things wrong, and now they are enshrined as 'vintage' and you can't mess with them. *sigh* I have to admit that being a 'vintage' guy myself, so to speak, it's hard for me to get excited over something that I could have bought new. Your call, I guess. I'd leave them out of the top, but put them in the case with a label, so that if somebody really has to have them........

Gad, I wish I'd bought a couple of Teles or Strats back when I was in hgh School, and just put the cases away.....

I had a student at one time who knew the folks who do the restoration for the Museum of Fine Arts in Boston. She said that have two formal curses that they recite every morning before starting work; one on people who use wood screws to 'repair' antique furniture, and another on yellow glue.

PVA and AR glues are not really very soluble in water. What you get in the bottle is a suspension of glue droplets emulsified in water; that's why it looks milky. The glue itself doesn't dissolve in water to any great extent, the water is just a carrier. Think of water born finishes as a counterpart. Anyway, water will soften AR and PVA glues eventually, because the emulsifiers are still there, but it takes a long time, and the wood usually goes to mush before the glue softens. Wetting the stuff is thus usually counterproductive in my experience: you end up taking off more wood than you would have if you'd just scraped the glue off carefully. note I said 'scraped'; old AR or PVA glue films don't sand well.

The museum folks did come up with a way to soften those glues, though: acetic acid. It reacts with the glue itself and softens it up pretty quickly. Vinegar is 3% acetic acid, and works reasonably well, particularly if it's hot. Photgrapher's stop bath is either 28% or 38% acetic acid (I forget which) and works much faster. The museum folks mix the acid in with a small amount of methyl cellulose powder, which forms a gel that keeps the stuff where you put it, and slows evaporation. This works much better on thick glue lines than thin ones, as the acid penetrates the glue faster than it soaks into wood. I used this one time to get a top off a bass violin that had been put on with Titebond: it took five hours, but it worked.

Acetic acid reacts with iron to form ferric acetate, which, in turn, reacts with tannins in wood to make a permanent black stain. This is how the old boys made black purfling. If you're using acetic acid to remove somethying that has been put on with Titebond, use a stainless steel spatula or knife.

I would not use vinegar to remove a glue film on something that's already apart like that bridge. That's what scrapers are made for. It's really good for getting things apart that have been badly glued together with 'way too much glue and not enough clamps or fitting. Then you allow everything to dry, and scrape the film off the surfaces before proper fitting and re-gluing.