shooting in the dark- how get glue into plywood

[Jack6]

Here's the situation:
a kay bass with internal separation in the plywood of the back. So far I've heard of two methods- making sliting and drilling holes and then somehow injecting glue in. Only until now none of the luthiers I've talked to has actually done this or even seen it done. I went ahead and made two even slits down the outer laminate, but I don't want to introduce glue until I've heard from someone who knows this procedure first hand. Hide glue? Gorilla glue?
Anyone out there know about this?

-Jack

[Randy Ward]

Jack6;

This doesn't answer your question but wouldn't it be easier to just replace the back? Since it is a Kay you can get a top or back from: http://www.engelhardtlink.com/parts.asp

Although the backs/tops are not listed on the site I've contacted them and they are available and reasonable.
I had a '49 Kay with extreme internal de-lamination problems and this is what was recommended to me for repair.

[Bob Branstetter]

Originally Posted by Jack6

Here's the situation:
a kay bass with internal separation in the plywood of the back. So far I've heard of two methods- making sliting and drilling holes and then somehow injecting glue in. Only until now none of the luthiers I've talked to has actually done this or even seen it done. I went ahead and made two even slits down the outer laminate, but I don't want to introduce glue until I've heard from someone who knows this procedure first hand. Hide glue? Gorilla glue?
Anyone out there know about this?

-Jack

Just to clarify, exactly where is the separation and how large is the delaminated area?

[robobass]

I did a laminate repair on a Suzuki bass once. I had the top off and the separation went from an edge to about 6" in. I forced the gap open with chopsticks or something and spread in hide glue with a paint brush. I don't remember how I clamped it. It worked well enough. It would certainly be more difficult to do if the separation were further away from an edge.
Robobass

[Jack6]

Originally Posted by Bob Branstetter

Just to clarify, exactly where is the separation and how large is the delaminated area?

I can hear a little click pressing almost anywhere in the lower back portion of the bass with the exception of the outer two inches or so. I think its in the outer ply, possibly the outer two plys. Sometimes the buzz is very sensitive and can be triggered by just about any note, or tapping anywhere on the body. At other times (and I can't really make out a pattern) it goes into remission completely and I cannot detect any movement inside the plywood. The slits i have made are about 10 inches long, spaced to give me the most coverage of that lower back area.

[Bob Branstetter]

Originally Posted by Jack6

I can hear a little click pressing almost anywhere in the lower back portion of the bass with the exception of the outer two inches or so. I think its in the outer ply, possibly the outer two plys. Sometimes the buzz is very sensitive and can be triggered by just about any note, or tapping anywhere on the body. At other times (and I can't really make out a pattern) it goes into remission completely and I cannot detect any movement inside the plywood. The slits i have made are about 10 inches long, spaced to give me the most coverage of that lower back area.

Has this bass been in a flood? If the area is as large as you seem to think it is, you have a problem that shooting glue into the plys without properly clamping it is not going to cure. My advise is to take the bass to an experienced luthier and get his opinion before you do anything else on your own.

[Matthew Tucker]

Originally Posted by Jack6

I went ahead and made two even slits down the outer laminate, but I don't want to introduce glue until I've heard from someone who knows this procedure first hand. Hide glue? Gorilla glue?

You've made the slits, you're committed to this repair, and if it doesn't work you'll need to get a new back anyway, so I'll give you my "non-luthier part-time woodworker, boatbuilder and hobby bassmaker" considered opinion.

You want a permanent bond. You are not conserving valuable wood. You need a glue that flows well into the crack, is slow to set to give you time to work with it, and has gap-filling properties.

That sounds like thin epoxy to me. You can either buy thin epoxy from a boating supplies shop like WEST system (better) or use some regular epoxy with a little solvent thinners.

I'd try injecting the thin epoxy with a hypodermic syringe with a large bloodletting needle and massage the ply till you see the epoxy emerge at another slit. Buy a bunch of syringes/needles because you'll probably only be able to use each syringe once because the epoxy solvent may soften the plastic. Do a test with a syringe first.

To clamp the laminate I'd try putting the bass face down between two saw horses (supporting the sides) and use long thin sticks propped against the ceiling to gently press on the outer ply. 100% internal contact probably is unnecessary - you need to stop the plys vibrating and separating any further. Check first before glueing that this doesn't deform the back. You'd need to be careful the edges of the slits lined up well too.

All that said, I'm answering your original question, but I'm a bit fearful of Bollbach's reaction!

I haven't seen your bass and although I have succesfully repaired bass laminates where they separate at the edges my experience with delaminated plywood is mainly with boats which have the added stress of constant immersion in water, so if its a valuable bass or if you're not 100% confident and patient to do tests first, and prepared to replace the back if it doesn't work, I'd let someone else experienced do it. You don't really want to muck up, 'cos Epoxy Is Forever

[TheSuzie]

If you do decide to use a garden variety epoxy, it can usually be thinned quite effectively with a bit of methanol - 90% style pharmacy rubbing alcohol works quite well. This will usually slow the set up time but it still seems to set OK. I have used this sort of mixture on armature windings of electric motors and also to pot electric bass and guitar pickups quite successfully. - YMMV

Peace,
S

[Jake deVilliers]

Holy Cow, an Epoxificator!

Matthew, I'm shocked.

Why wouldn't you just use regular Franklin Titebond which is thinnable with water, will pump into the gap and is fixable?

Good advice about making sure you retain the original arch of the plate. Ideally you'd make a caul that fits well and clamp it to that. I believe that Kay's have identical front and rear plate curvatures from being made on the same mold.

Jake

[Matthew Tucker]

Originally Posted by Jake deVilliers

Holy Cow, an Epoxificator!
Matthew, I'm shocked.

I'm of the opinion that every glue has an appropriate application. I've had good results fixing delaminations with epoxy and no experience with Titebond - which sounds like a claytons hide glue to me. So there you go!

And I love hide glue and use it where others tell me to use epoxy. You make your choice and you takes yer chances ...

As far as a shaped caul is concerned, it didn't sound as if the punter was intending to remove the plate from the bass, but doing the repair in situ. If removal of the plate was on the cards, a different solution might well be better.

[Damon Rondeau]

Nah, TiteBond is like yer basic yellow carpenter's glue. Poly-syllabic something or other, soluble in water. Not pre-made liquid hide glue.

There is also a very thin cyanoacrylate (Krazy Glue) glue available through Lee Valley designed for fixing chairs. It wicks into spaces and gaps and swells the local wood fibres, in theory locking loose joints as a result.

But it sounds like you've got a very large delamination there. If it's that large, what makes you think it's just one ply that's wonky? Could be more extensive....

I don't see much unreasonable in Matthew's epoxy recommendation given the caveats. Sounds like a lot of stiff epoxy to be in that back, though...

[Jake deVilliers]

The yellow glue would be removable in case our beginning repairman doesn't get it quite right the first time.

The caul is to help keep the shape, as he's got a 10" cut in the plate.

Ignore me as necessary, I won't be offended, but I have done this repair before.

Jake

[Jack6]

So I listened to all the advice I could and after a weekend of fierce buzzing I had an instrument repair friend come over and take this thing on with me.
I decided that injecting blindly was too...blind so I went ahead and cut out a small square out of the outer laminate and worked in glue with a long palette knife (not much of a gap, but not much resistance either). Two drops of water in the glue it make it travel farther. We massaged the back to work it around, put the square back in place and the clamped the whole thing up with nylon straps (car rack kind), bulletin board cork and bunch of books. With the books worked in under the straps, there was enough tension to get a high tone plucking on the straps. I left it for a full day. And then I took off the bandages...

Three bubbles, had formed right around the orginal slit and the square patch- the laminate had swelled with the moisture and fought its way up against all the pressure. The buzz stayed away for a few days, but now reappears periodically in an altered form. So... a bit of regret, but I felt I had to give it a shot- I just couldn't find any luthiers around who had done this repair. Now wondering how I can at least get the outer laminate to lay flat again.

Any more ideas out there? A new back is 170 from Englehart, but won't sound like this one.

[Bob Branstetter]

Originally Posted by Jack6

A new back is 170 from Englehart, but won't sound like this one.

You're right. A new Englehardt back won't buzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.....

[Heifetzbass]

What kind of glue did you end up using?

[Matthew Tucker]

Originally Posted by Jack6

Three bubbles, had formed right around the orginal slit and the square patch- the laminate had swelled with the moisture and fought its way up against all the pressure.

Eeeeeooouuuww! no pics please !!!!

[Jack6]

I had used titebond the first time. Then after the damage, with the help of a good luthier friend, it was structural epoxy, clamped under half inch plexiglass, a 25 pound bag of lead reinforced with a board and two rachet straps. That made it lie down and hold still. The buzz just reappeared this morning in a subdued state, but I no longer have much hope of solving it through operations. Its tolerable for now and if it gets worse again I'll probably go ahead and get the new back.

[GerardSamija]

Originally Posted by Damon Rondeau

Nah, TiteBond is like yer basic yellow carpenter's glue. Poly-syllabic something or other, soluble in water. Not pre-made liquid hide glue.

Um, no. Sorry for the revival of this ancient thread, but... I've a small bottle of Franklin brand Titebond glue in front of me (use a tiny drop for adhering bow frog spreading wedges to the ebony side, and the odd other low-strength application) and can say with certainty that just beneath the name 'Titebond' is the secondary name 'Liquid Hide Glue.' I've used two 4oz. bottles of this stuff over the past 20 or so years. Ages very well, so the preservative to keep the proteins from rotting must be pretty good (ie; very toxic). For applications where one isn't too worried about brute strength, especially when the bond is expected to be reversed at some later date, it's a very convenient solution. Sets up almost glass-hard, but a bit of water and a few minutes' wait make it pretty much like it is in the bottle.

As for laminate buzzes, another possible issue can be knots embedded somewhere in the layers. I'm quite sure that must have been the case with an old German ply bass back I tried to de-buzz years ago. It was back in '97 or '98, and the bassist loved the sound of his hybrid, but the buzzing was just getting worse. I tried a lot of hunting, but finally had to start drilling tiny holes (1mm) and injecting glue with a Lee Valley glue syringe. The glue I settled upon was also from Lee Valley, called 'Chair Doctor.' It's a white, water-based glue with very low viscosity. About like whole milk. With surprisingly little bulk loss on drying, it penetrates well into any open-grained wood, and has a somewhat plastic-like hardness when set. Not the strongest glue, like Titebond, but the easy flow characteristic makes it ideal for such applications - after all, it's made to be injected into loose mortise and tenon joints on chairs to avoid disassembly when they're loose.

The buzz did not get gone, sadly. I must have drilled over 100 holes in that poor back, injecting lots of glue and then filling the holes with tiny wood pegs. From further than about 5 feet away it didn't look bad, but up close it was horrible to see all those little maple pins in the flamed blonde back veneer. The guy took it to another luthier, who drilled lots more holes and injected whatever (we have no idea), and failed just the same. All I can think is that there was a knot, somewhere in the 5 layers of that back, and it had come loose, buzzing like crazy on certain notes. No cure shy of making a new back it seems.

In weird glue territory, today I opened up a 1971 Suzuki ply bass. A couple of others have given gluing a try on various loose seams, but it's kept coming apart. Taking the back off (the most loose part) revealed the problem; it seems a sort of white starch was used for glue. Never seen that before, so I was searching the forums for other cases and stumbled across this thread. So far no luck finding any other cases though. This stuff is really brittle, flakes off with the lightest touch of a blade. The ribs were completely loose from the neck - I cleaned that out and re-glued those right away - and the back was almost falling off. The belly seems a bit better, probably owing to the previous repair attempts. The bassbar was flapping in the breeze at the lower end, and grabbing that between thumb and forefinger and lifting it took the thing off cleanly in a second. Amazing it hadn't just fallen off before. This is a highschool bass, much used, so I'm pulling apart anything that's loose and re-gluing it properly once cleaned. Sure would be nice to know what that white starchy stuff was though. Tried dissolving it in warm water, but it didn't melt... got a bit softer is all.

[Damon Rondeau]

Well, there are a lot of glues that go under the Titebond brand name, as you can see here.

They do in fact make a liquid hide glue, and I guess my ancient comments here tended to exclude that. But as a guy who's not a luthier but who has been a woodworker for decades -- actively doing, making, reading, learning -- I can say confidently that the first glue an experienced person thinks of when somebody says "Titebond" ain't hide glue. No how, no way.

[GerardSamija]

Ah, it becomes clearer. Thanks for that Damon. In fact I do recall reading a book about James D'Aquisto's jazz guitar making, by a German author if memory serves (it was in 1986 I think, so a bit fuzzy now), in which a white glue was being used to join the neck into the block. The maker was making a big thing out of how this was a 'get it right the first time, or else' sort of gluing job, as the Titebond glue was not easy to get apart once the joint locked. Like I say, memory might be off there, but that would confirm the multi-uses of the Titebond name. A bit odd, but then again I guess it is a nice name to use for glues. Kind of reassuring.