Glue recommendations for repairs

[landolaguitar]

Hi everyone. I'm looking into repairing soundboard cracks, correcting belly bulge and replacing bracing on two of my classical guitars. What glue would you recommend for filling top and back cracks, re-gluing the bridge and finally re-gluing the braces? Any input appreciated

[Bowie]

Titebond is the most common as it works well and is user friendly. I greatly prefer hide glue for a number of reasons but it takes some familiarity and skill while Titebond is far more forgiving.

[John Arnold]

Titebond Original. Titebond II and III are for water resistance. They are not stronger.

[phavriluk]

'Replacing bracing'?
This sounds like major, and careful, surgery.
Through the soundhole?
And the question is about which glue to use?
Prior experience?

[landolaguitar]

Thanks everyone. Titebond appears to be the choice of many. As far as experience replacing bracing I have none. But the bracing is severely damaged so it can't really get any worse

[runamuck]

Originally Posted by landolaguitar

Hi everyone. I'm looking into repairing soundboard cracks, correcting belly bulge and replacing bracing on two of my classical guitars. What glue would you recommend for filling top and back cracks, re-gluing the bridge and finally re-gluing the braces? Any input appreciated

I agree with other comments here about using Titebond (original, not 2 or 3).

BUT Titebond works only on wood to wood surfaces and is comparatively weak if there is existing glue on either surface. In other words, you need to completely remove any existing glue. For bracing and the bridge Titebond is probably your best bet unless you're experienced with hot hide glue.

Filling the top and back cracks may be another issue depending on exactly what the problem is. Titebond can work if you can clean the mating surfaces and clamp the cracks together; CA glue might be better if you can't. A photo might be helpful here.

[landolaguitar]

Thanks for the input everyone, I'll try send some pictures to give a clearer idea of what I'm up against but basically one of the guitars(the one I'm most concerned with repairing) has a split in the top behind the bridge

[viento]

In addition to the reliabble Titebond, I also like to use fishglue.It is strong and can be removed again like Titebond.

[Howard Klepper]

Never use glue to fill a crack.

[Henning]

Originally Posted by landolaguitar

Thanks for the input everyone, I'll try send some pictures to give a clearer idea of what I'm up against but basically one of the guitars(the one I'm most concerned with repairing) has a split in the top behind the bridge

Send up a few photos of the crack and eventually the bracing you intend to repair too. Might help judging the matter a bit.

[Henning]

Originally Posted by Howard Klepper

Never use glue to fill a crack.

Howard please, why not?

[Bruce Sexauer]

Our popular woodworking glues use electro-chemical bonding to create their power, not that I understand that, but they have very little strength when stretched beyond a molecular film. That means they are lousy for gap filling. Epoxy, and to some degree, CA are the exceptions. I have philosophical issues with using epoxy in acoustic instruments. Titebond is a terrible choice for RE-gluing braces as it barely sticks to previously glued surfaces. Getting old Titebond out from between a brace and a plate is challenging even even when the brace is removed, let alone in place.

I disagree that the learning curve on HHG is a big deal, and it is almost certainly the best choice. Try it, you’ll like it.

[redir]

In the 'old days' they would fill a crack with sawdust and hide glue. I've seen many a vintage guitar with that kind of repair and some have held up well, surprisingly.

I agree with the sentiment, never fill a crack with glue. If it's not a vintage guitar and repair costs are an issue then I will color West System epoxy to the wood tone and fill it with that. It sounds sacrilege but again it depends on the instrument and other circumstances.

If cracks do not shut under normal humidity then they typically are splinted, which is to say they are fitted with a splint of matching spruce and there are various ways of doing that too.

[Henning]

Will HHG be weaker if reheated? Does the glue loose its ability to function as a glue, please? That would be loose its ability to connect two pieces securely. I've think I've read that somewhere. I have a small amount of HHG in the the freezer for some time back. HHG is basically a protein and to work properly the two surfaces that are to be glued together need a better joint then for instance titebond needs.
Regards

[maxtheaxe]

Originally Posted by Bruce Sexauer

Our popular woodworking glues use electro-chemical bonding to create their power, not that I understand that, but they have very little strength when stretched beyond a molecular film. That means they are lousy for gap filling. Epoxy, and to some degree, CA are the exceptions. I have philosophical issues with using epoxy in acoustic instruments. Titebond is a terrible choice for RE-gluing braces as it barely sticks to previously glued surfaces. Getting old Titebond out from between a brace and a plate is challenging even even when the brace is removed, let alone in place.

I disagree that the learning curve on HHG is a big deal, and it is almost certainly the best choice. Try it, you’ll like it.

I don't remember where I heard this, but I was told that a combination/mixture of HHG and CA was a good one; the theory was that the CA grabbed & held fast, but became less strong over time, and that the HHG started out weaker, but becomes stronger and more permanent with time, therefore, as the CA was giving up, the HHG was taking over...or something like that.

Your take on this?