Thread: Glue for Indian Rosewood on Cedar or Pine

I've only made one guitar, but it's survived over 10 years. I used Titebond Original to glue the bridge to the sound board. I recall the plans calling for the glued face of the bridge to be heavily scored with a knife before gluing.

It could also be the resins in the rosewood preventing the glue from keying to it properly. If so, switching glues won't really 'fix' anything.

When you did the glue-up did you wipe down the rosewood with acetone, metho or a similar solvent (to remove surface oils/resins) immediately before gluing?

Originally Posted by Skew ChiDAMN!!

It could also be the resins in the rosewood preventing the glue from keying to it properly. If so, switching glues won't really 'fix' anything.

When you did the glue-up did you wipe down the rosewood with acetone, metho or a similar solvent (to remove surface oils/resins) immediately before gluing?

2 Ukeleles - 1 glued without wiping with acetone and subsequently failed - reglued after wiping with acetone and failed again. second ukulele was glued after wiping with acetone to start with and it too failed. Now I have two ukuleles without bridges until I decide what to do.

Glue quality (and/or age) may be and issue, but the same glue has been working fine in other applications. Inspection of the failed joints reveals that there is NO glue on the rosewood and plenty of glue (that requires scrapping and sanding) on the cedar/bunya pine ukulele tops.

I'm beginning to think that the cause is using low quality (no name) or old PVA and perhaps poor/uneven clamping pressure (I do not have a bridge clamp, so I just applied pressure using rubber straps onto a pice of wood that pressed down on the wood) - Neither poor glue or poor calmping technique explains why the glue is well adhered to one timber and not the other.

I think I will try again on a roughened bridge, cleaned with acetone until no pigment is visible on a white wipe, and glued immediately after the acetone has dried (so that the resin from inside the rosewood does not have time to resurface) using fresh name brand PVA or hide glue... and clamped more conventionally for a good long time. Epoxy is supposed to stick to anything, but its starting to sound to be the wrong choice as the joint is likely to be irreparable if it fails again. Millions of bridges must have been glued down with PVA or hide.

If one of you had said definitely try Epoxy citing experience then I probably would have tried it

Thanks!

Originally Posted by GarciaJ

I'm beginning to think that the cause is using low quality (no name) or old PVA and perhaps poor/uneven clamping pressure (I do not have a bridge clamp, so I just applied pressure using rubber straps onto a pice of wood that pressed down on the wood)

It may indeed be the glue, as you only get what you pay for. I doubt it's an issue with clamping, unless you're over clamping and squeezing the glue out. But it doesn't sound like that's the case. After all, rubbed joints tend to be just as strong as correctly clamped joints.

Neither poor glue or poor calmping technique explains why the glue is well adhered to one timber and not the other.

Not by themselves, no. However, I can create just such a joint failure with two strips of the same wood by simply burnishing the glue face of one, preventing the glue from keying. So I'm inclined to agree that roughing the rosewood would increase your odds of success.

I'm hesitant to recommend epoxy, not only because it complicates possible future repairs but because it also tends to be quite rigid once cured. PVA and hide glues have an element of flexibility.

Well... at least until they're well aged, anyway.

Not that I've any experience with luthiery but I enjoy segmented work and will avoid epoxy except, occasionally, for infills.

For less delicate work, it's a different story.

Originally Posted by Skew ChiDAMN!!

It may indeed be the glue, as you only get what you pay for. I doubt it's an issue with clamping, unless you're over clamping and squeezing the glue out. But it doesn't sound like that's the case. After all, rubbed joints tend to be just as strong as correctly clamped joints.



Not by themselves, no. However, I can create just such a joint failure with two strips of the same wood by simply burnishing the glue face of one, preventing the glue from keying. So I'm inclined to agree that roughing the rosewood would increase your odds of success.

I'm hesitant to recommend epoxy, not only because it complicates possible future repairs but because it also tends to be quite rigid once cured. PVA and hide glues have an element of flexibility.

Well... at least until they're well aged, anyway.

Not that I've any experience with luthiery but I enjoy segmented work and will avoid epoxy except, occasionally, for infills.

For less delicate work, it's a different story.

Yes - I think that the resinous rosewood provides an oily interface. I was dissapointed that wiping with acetone until the cloth I use top wipe cloth did not pick up any pigment did not help.

Even so the problem is probably caused by a combination of factors, so to repair I think I will roughen, clean with alcohol, use Titebond or the like and clamp lightly using a bridge clamp.

I agree that clamping is not normally an issue, but in this case its possible that clamping from one side only is cupping the ukulele top, cuasing the two surfaces not to mate properly. Having said that I did not see any evidence that this was happening.

Thank you for your replies.

Originally Posted by GarciaJ

I was dissapointed that wiping with acetone until the cloth I use top wipe cloth did not pick up any pigment did not help.

There's a school of thought that wiping oily woods with solvent just draws up more oil from below the surface.
I think your solution is mechanical keying and fresh glue of a known pedigree. Titebond original is the goto glue for many luthiers. Proper clamping ensures no voids.

An example here of keying the mating surfaces:
Acoustic Guitar Bridge Regluing