Araldite or wood glue?

[JimT]

Can anyone tell me if Araldite would be as strong as wood glue for the following application? It's a guitar restoration job; I need to glue a rosewood bridge onto the spruce top of an acoustic guitar. Why am I thinking of using Araldite, instead of wood glue?... It's a restoration job, and the old bridge is somewhat distorted, whereas the top of the guitar is dead flat. If I use araldite, the glue will fill out the spaces betwen the warped bridge and the flat surface, whereas wood glue won't. Wood glue shrinks as it dries out and therefor won't fill out those spaces. The resulting joint needs to be as strong as possible.

Many thanks

JimT

[sPoNiX]

[Glen]

Hi Jim...

A few places for you to ask this question.....either on the rec.music.makers.guitars.acoustic newsgroup, or on the nets best acoustic guitar forum,

. There are many top/amateur luthiers who hang out here (...along with plain old guitar loving joes like me....), and they are more glad to provide such answers. A friendlier forum you probably won't find.

cheers Glen

[gribblechips]

If the bridge has a replaceable saddle, I would be tempted to sand the bottom of the bridge flat and then use a wood glue. Then use a new saddle to get the stings up to the height you`ve lost by sanding.

At least then you`ll have the option of trying again if you fit it up and find that the intonation is all out. You won`t get epoxy off.

That said it`s probably a good idea to ask somone who does this sort of thing all the time as suggested above.

Will

[JimT]

Thanks for the suggestion, but I cannot sand anything off the bottom of the brisge, because it has two thin fancy bits that protrude from each end.

Jim

[JimT]

Hi Glen, Thanks for the lead. I wasn't aware of

Will take a look.

Jim

[Cicero]

================ There are many different kinds of wood glue.

'Cascamite' is a water-proof dry powder glue which is mixed with water and it can also have sawdust mixed in to create bulk which is what you require. Screwfix sell their own version under the trade name, 'Extramite'. Have a look at:

if you can't find 'Cascamite' which you may need to buy from a good tool / hardware shop.

p.s. Just out of curiosity, are you sure that the bridge should be glued? I really don't know anything about guitar bridges but as far as I know the bridges on other stringed instruments such as violins are loose fitted and held in place by the tension of the strings. Perhaps someone will confirm or otherwise?

Cic.

[tony sayer]

In article , Cicero writes

ISTR that this is the case. My fist wife's father was a violin maker and I think that the string tension was what did the trick. In any case the strings should be able to hold it without any trouble unless he/she is going at 10 times the speed of Nick Pagaini:)

[JimT]

Hi Cicero, I remember Cascamite from when I was a kid, about 45 years ago!

Thanks for the tip.

Yes; absolutely. Admittedly thee *are* some guitars that have non-glued bridges (archtops, sometimes). But on most acoustic guitars, the bridge is glued on and the strings are attached to it by means of pegs (bridge pins) that pass right through the bridge and the guitar's top.

Jim

[JimT]

PS.. could you tell me why cascamite mixed with sawdust would be better than everyday wood glue mixed with sawdust?

Thanks

Jim

[gribblechips]

Some guitars do use a similar arrangement with the bridge held down by string tension, as on a violin. This does however require as (again as in a violin) a tailpiece to hold the tension of the strings. Most acoustic and classical guitars fix the strings to the bridge and it consequently needs sticking down quite firmly to cope with the tension which can be substantial.

Will

[Cicero]

============ I'm not really sure except that you can do a stiff mix with cascamite which will hold the added sawdust. Standard ready-mixed glue has only one consistency and as you know it's usually pretty 'runny' . Of course if you wanted you could delay bringing the parts together until the glue gets close to the end of its 'open' time.

Since you remember Cascamite from school days you may also remember the use of a 'rubbed joint' made with the old animal glue. The technique was to glue both surfaces to be joined and then slide them against each other until you could get almost no further movement. At this stage you allowed the glue to set and the result was a strong joint with no gaps in the glue. It might be worth a try as it's a traditional method.

Cic.

[NoSpamThanks]

just as long as you don't miss out the th ;-)

[Jerry Built]

I should have thought pearl glue would be most appropriate for this - it is for violins, cellos etc (if they're of any quality). I would also be tempted to improve the mating of the joint. Perhaps you could hold the bridge between blocks, and flat it with abrasive paper on an offcut of planed timber. It would also be worth cleaning the face. If this is no good or not worthwhile, I'd use old-fashioned (non fast curing) Araldite.

J.B.

[JimT]

No - I can't remember any animal glue at all. However, this guitar which was made at the beginning of the 20th century was indeed constructed with some sort of animal glue. I found that when I soaked the bridge in water, the very hard glue on the underside turned to a sort of jelly - I wondered if it might be glue maid from boiled hooves, fish heads or whatever.

Thanks for the suggestion. A purist mightt have wanted to do this repair using period methods, but it wouldn't solve the problem of the gaps in the mating surfaces. I'm not sure where one would get old-fasioned animal glue anyway... and I have no qualms about using modern materials. Whatever does the job best..

Jim

[JimT]

Thanks JB - I'm leaning towards Araldite. I'm not the kind of purist who wants to use traditional glues. I just want something that works, is strong, and will last.

Jim

[Cicero]

============== I'm sure that you could get the old-fashioned animal glue if it became a real issue but as you're more concerned with getting a playable guitar then the best glue is almost certainly a modern one. The only reservation I would have is that the wooden parts you're trying to join will be contaminated by the old glue (whatever it was) because by its nature glue sinks into the wood. You'll need very thorough cleaning before using a different glue from that used originally. If you use Cascamite mixed with sawdust as I originally suggested you might be able to build up a fillet at the base of your bridge where it meets the guitar body. I don't know what that will do for the acoustics but at least it will make a stronger joint.

Cic.

Cic.

[Andy Dingley]

Well no, but do you really care ?

Araldite is not a good epoxy to use (but it's probably convenient). You're always better off using a simple unadulterated epoxy resin (like West Systems) and mixing in the right fillers for the job in hand. Araldite is chock full of gunge to make it store well and easy to mix, and that spoils its behaviour as an adhesive.

Also epoxy is rigid and unmoving, whereas wood shifts with moisture. Make a wide cross-grain joint and it's likely to crack off (JB Weld is even worse).

There's also the conservation aspect. Epoxy fixes most things, but it makes them a real pain to fix next time around. I'd incline to a hide glue, especially for anything musical. As you've noticed, it's dismantleable by damp heat in the future.

This is the _bridge_ FFS ! Fool around with JB Weld here and it'll sound like a dustbin afterwards.

If you don't want to fool around with hot hide glue (pearl glue), then find a decent toolshop (like

and get a tube of Titebond's cold liquid hide glue. Dead easy to use, handy for veneer repairs too (or even leather straps!), and it's the right stuff.

[The Natural Philosopher]

Epoxy will do the job, but I am a bit bervous about introducing it between teh bridge and boidy. Acoustics etc. I'd definitely try and stick a bit of emery paper on te bosy and sand teh bridge to match to get as near as possible wood-to-wood contact with just a little glue line in there.

Then I'd probably use cyanoacrylate meself...

[The Natural Philosopher]

(acoustic) Guitar bridges mostly hold thee strings as well so need to be strong in shear.