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Just had something bad happen and dont know what to do. I had a perfect invisible seam using titebond on a sikta spruce top. had my rosette installed and was thiknessing the top. i went to shake it to hear if it was getting the sheet metal sound and it broke in half all the way down the seam. it lines up perfectly threw the rosette and everything to where if i glued it back together you would never be able to tell. the only thing is i cant mess with the seam at all because of pieces going back together at the rosette. how should i go about fixing this i was thinking i would maybe try ca glue since i cant sand the joint but i dont want a dark line either. could i use titebond again or do you need a fresh seam for that. any advice?

God knows I'm no expert, but here is what my thought process would be:

1. If it split at the actual glue line, then you would need to clean the joint in order to re-glue there, because you used Titebond, and new Titebond does not stick well to dry Titebond.

2. You would want to redo that joint anyway, because while it may have seemed invisible to you, it obviously wasn't a good joint in the first place. It popped under stress that it should be able to handle.

3. Redoing the joint is a hassle, because of the rosette.

4. You have not yet braced the top, so while this stinks, it is not as bad as having a problem after going to the trouble of bracing.

5. All of this leads me to think that scrapping it and starting over with a new top is the best way to go. Top wood is not crazy expensive, you can use parts of this one for other things, and you will know the new top will be in better shape than you will ever be able to get this one into.

Just my opinion.

To get a good bond, you'd need to clean out all the old glue, unless it's hide glue. CA won't work on old glue, and it discolors spruce sometimes. If you really want to do it right, you'd need to give up the rosette. Cut it out with a router and start over. If it were me, I'd toss the top and start from square one. Done that more times than I like to recall, though for different reasons from yours. With a new top, you could use the old top to experiment with to make sure you have the process down to get a strong joint. Don't shoot the messenger!

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Probably toast, you need fresh wood for a new join, so there go's your rosette. Bummer

My hunch for cause would be over clamping and creating a glue starved joint.

I have to side with the start over with a new top guys, but only after you clear the glue out of the old seam and give it a chance to work.

As a side note, I think glue joints in thin wood require a different technique than in gluing thicker wood.

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Joe Beaver
Maker of Sawdust

Vinegar will soften dried titebond glue. After you soften it, careful scraping with a single edge razor blade will remove it without taking wood. After cleaning the glue off, rinse with clean water and allow to dry. Check the fit of the seam from the sound hole to the tail end. This is the only area that needs to be perfect. Sometimes opening up the soundhole and making a less than perfect joint above it allows the lower end to fit tighter.
I would reglue with HHG, but barring that you could reglue with titebond.
That is what I would do, and if the joint looked good I would glue a couple of cleats under the joint and use the top.
It is possible to inlay a 1/2 depth spruce patch from rosette to tail to hide a bad looking seam, but that is a lot more work and might also "go south".

I'll just add to what Don said. The gluing operation you face now is more involved than the first time pre rosette glue up.
It's hard to say without seeing it but the seam probably wasn't jointed or glued up properly? IMO this joint requires the
most attention to any on a guitar. My advice would be to use this top to practice preparing and gluing/clamping, then start
with a fresh one. Many aspects of guitar building are mostly cosmetic, not this one however. I'm sure the rosette could be
salvaged for reuse. Be glad that you're in this situation now rather than say when you're just about ready to string it up.
Or you could just glue it up again and hope for the best.
Ken

If it's actually separated at the glue line, something is very wrong with your jointing process. A properly glued joint will be stronger than the wood beside it.

There is a reason your top split at the seam and you should address that first before you go any further. I would inspect the broken seam using a magnifying glass to check if it actually split at the glue line or to the side of it. If you see wood at the broken seam then the glue joint didn't fail, the wood split beside the glue line. In that case you should be able to glue it back together with no worries about the Titebond not adhering to itself.

If you see the glue line at the break then your joint failed and you need to find out why. Chances are you clamped it too tight and starved the joint. Another reason could be that you sanded the edges to prep them for gluing and left sanding dust on the edge which may have weakened the joint.

If the later is the case then I would consider just setting this top aside and start over since you will probably not get a good clean joint and the rosette may not fit as well as it did.

That is my take,

Bob

I see you're in SD. How cold was your shop when you glued it up? If it was much under 60 I'd be suspect of the glue chalking which makes for a very weak joint.

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Jim Watts
http://jameswattsguitars.com

So the glue joint broke instead of the wood beside it?

My thoughts.

#1 is old glue problems or the glue too dried out and gloppy to adhere right.... Throw out that bottle and buy a new one.

#2 is too much open time with glue applied jiggering around with your clamps and gluing jig before you clamped it together good.

#3 is an old, contaminated, or wet glue surface. Did you prep it significantly before you glued.... Say did all the jointing and then glued a couple days later... Or perhaps used sandpaper that had been previously used on rosewood... Or wiped down the wood with some sort of solvent or water prior to gluing.

Yes - you will need to re-joint the seam all over again... You will need to get rid of all the old glue that didn't stick.

The one time this happened to me - the surface of the wood was wet when I glued it... It just peeled right apart at a spectacular invisible glue joint.

Start over with a new top unless the top is plenty thick. As others have pointed out, this should not have happened. Titebond is incredibly resistant to operator error unlike something like hide glue. Route out your rosette and start over - make sure you "candle" the joint and make sure your Titebond is fresh. Sorry you are having trouble but think of it as a good learning experience!!!

out of all the responses the one that sounds like i did wrong was got the joint to tight when i clamped it. i use a shooting board and angle one side and wedge it between two boards. i had it super tight in there thinking it was better to have it tight. this is only my 3rd guitar and first time that happend. i guess i need to stop geting the joint so tight. i see some people use tape. maybe i should try that mothod.

I don't entirely trust the tape method. Titebond does require a certain psi that I doubt you can achieve with just tape. I use the tape to get it started and keep it aligned before it goes in the clamping jig. The only joints I've had fail have been tape alone...

Unless you are using epoxy a "starved" glue joint is more of a idea than a reality. I seriously doubt that you could over clamp your top without buckling it and I would be surprised if your joint was that perfect.
Did you use a hand plane?
When you say invisible was it invisible with very light pressure or after you clamped it.
Be sure to wet out both surfaces of your joint. What I typically do is apply glue and put joint together, pull apart and respread.
I would do some practice joints and break them to see if your technique if good.
I use tape clamping only on veneers I will glue to a sub-straight. I agree with meddling fool about the tape. With hide glue on a top, ok if your technique is up to it, with a hardwood back in a difficult wood like coco or rosewood, no way. Especially in light of how much a lot of folks "seam" have trouble with joining tops and backs I would really discourage them from the tape clamp method.
L.

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Cut to size.....Beat to fit.....Paint to match.

It is a good and wise thing to try to figure out how this joint went wrong, but it is unwise to spend too much time dwelling on it, because you might not ever be able to figure out the precise reason. It could have been a number of things. I would just start over with a new top, follow good procedures more carefully and intently this time, and move on. Crap happens. Like I said above, at least you had not braced the whole top before discovering the problem. Use fresh glue, cut as good a joint as you can, use enough glue, use moderate clamping pressure, etc. I bet it will work out fine the next time, because you will be on the lookout for anything the folks here have identified as the potential cause of this prior joint failure.

Humidity is something to think about. Or the lack of it.

yeah i dont think that will be happening again. im using the broken top to practice now that its shot. my guitar building room has a humidifier and humidistat that keeps it between 42 and 45 humidity so humidity is not an issue. i have never wetted any of my glue joints but i guess i will be starting now

I would not expect humidity to have anything to do with it, as there is nothing but the rosette glued across the grain.

I also wanted to mention, about the sheet metal test, as it were, that that is only reflective of cross grain stiffness, which is relatively unimportant compared to long grain stiffness, which is what resists string tension...

Don't wet anything with water.... That's a great way to have the next one fail..

What he was talking about is to apply a bead of glue to both faces and spread it with your finger to ensure the glue fully soaks into the wood on both sides before you clamp the pieces together.

I use to also think you couldn't actually starve a titebond joint but now believe you can, especially when it is a joint in thin wood.

When you glue wider wood, say 3/8" or more, the glue reluctantly moves toward the edges under clamp pressure and some squeezes out, but some stays behind and migrates in to the wood fibers. In thin wood, since it just has a little way to go to be out of the joint it is easy to have too thin a glue layer.

What I do now is put titebond on both pieces, put them together gently, which keeps the glue from skinning over, and wait a few minutes. Then I rub them together a little but not to much, kind of like a rub joint. Once I feel the glue thicken I clamp, just a little at first then in a minute increase to moderate pressure.

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Joe Beaver
Maker of Sawdust

." i see some people use tape. maybe i should try that mothod."

I have used the tape method for more than 25 years and have never had a problem with it. You need a well made joint and a stretchy masking tape that will pull the joint tight. I have used titebond and hide glue with this method and always had good results gluing both hardwoods and softwoods.

Titebond is a very forgiving glue. The only time I have seen it completely fail is when it is subjected to cold temperatures (below 60 degrees, as Jim Watts mentioned) before it had cured. It leaves a chalky appearance.

We use a wedged and taped joint - tape for alignment and quick (but minimal) pressure to thin the glue line, plus wedges to apply a few hundred pounds of clamping force to ensure the glue line is thinned to invisibility. Wedges alone can risk alignment issues with the hot hide glue we use, and tape alone risks the low glue line pressure that may result in a visible glue line, which we see every so often on both factory and small shop guitars.

Any clamping scheme used needs to ensure the plate remains flat during glue-up and drying - it takes surprisingly little pressure to buckle a top or back, so we use two weights to keep things flat after the joint is closed and while the wedges are tapped in/center seam wedges are added to keep the plate tight to the clamping board. Lack of much in the way of a bucking tendency (and clamping effect) is one of the advantages of a tape scheme, so using it to get some preliminary pressure while getting the glue line under greater clamping pressure plays to the strengths of both techniques while minimizing their shortcomings.

If the plate is allowed to bow (which is to say clamped with pressure exceeding the force needed to buckle the plate), one side of the joint may open, resulting in what might seem like a joint with insufficient glue.

A few considerations for either rejoining or reusing the top:

- If the plate has been thinned to near final thickness, your glue-up must be very accurate to avoid losing some thickness...perhaps use both tape for alignment and your wedge system for clamping pressure, and consider whether a thinner top might be better used for another, smaller-bodied project or gifted to a builder of double topped instruments.

- By ripping on the center line joint and rejoining using what were the outside edges as the new center seam, you may find that the remains of your rosette fall outside the body outline. If some element of the rosette still remains in the body outline near the waist, and the appearance of the reverse side is acceptable (well-quartered tops may look very similar on both sides, despite a less-than-perfect book match), the top can be flipped and the remaining elements of the rosette placed close enough to the rim that there is little impact on stiffness. In the event the grain line spacing is noticeably different (closer spacing on the edge of the top versus near the sound hole), you might suggest that it is your little experiment in redistribution of top stiffness .

- A 000 or dreadnought top may be cut down such that the remains of the rosette are contained within the sound hole cutout of an 0 or smaller guitar. My Lutz-topped 12 fret 0 uses the salvaged top from another builder's SJ effort...I saved close to $100 and got a perfectly quartered, handsomely silked top. This approach might not yield immediate resolution of your current top woes, but it might address a future small bodied project's needs.

- Smaller guitars typically use thinner tops for a given top wood, so the 5 to 10 thousandths lost in joining and installing a rosette will likely be less consequential than for a larger bodied project.

Good luck with your rescue or recycling effort!

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Top should not have split along the glue line. It should have broken the wood. Ragged split. Just start over a learn from this. Try the Spanish clamping system. I've never done that shaking thing. I get it to .11- .12" and stop. Further sanding after mounted will take it down more.