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Cyanoacrylate for wood clarinets cracks: glue or filler?

11K views 30 replies 10 participants last post by  Henning1 
#1 ·
First of all I want to apologise for asking this question that has close relation to repairing wood cracks with cyanoacrylate (CA) on clarinets but it is not solely about clarinets. Forgive me and if the moderator will be generous enough to keep my thread alive I appreciate it.

Once again this is closely related to the subject of CA crack repairs on clarinets but is more of a general nature. I hope someone with deeper knowledge of the subject will demistify the very nature of this repair. In other words: why does it *actually* work?

So, first let's assume we have a crack in the clarinet body (I'll expand this later to one other use that I'm at the moment very concerned about so please bear with me).
There are a number of threads on SOTW and elsewhere about the procedure of how to apply the CA to the crack, well it's simple enough. Once the crack is filled and the CA cures many report that the crack never opens afterwards. More sceptical repairers insist on pinning but the first group insists that CA is all that is needed to keep the crack from further opening up. Let's leave that argument to another thread (actually I remember there was already such a thread on SOTW or elsewhere).

So, now to the subject of my question and again sorry for such a long preamble!

When the clarinet crack is filled with the CA does CA act more like a glue or more like a filler with glueing capabilities or... maybe a glue with filling capabilities?

Why the question? I don't know what force in terms of psi is being applied to the glued (or filled?) crack by the wood when it wants to open up the crack again but I assume that it's powerful enough since even pinned cracks sometimes open up. So, is it glue then?

Now, let's expand the area of application a little to get even closer to the subject.

Assume you have a piece of wood that is cracked along the fibers in half but it's not one piece with a crack in this case but you have two separate parts that you need to glue together.
Assume also that you have only two "glues" as a choice for the puropse of this discussion:
- very popular among woodworkers Titebond and
- our favourite friend the CA

Can you achieve similar results in terms of strength when restoring the integrity of that piece of wood when using either of the two glues? Here I don't know how to clarify my question to explain what I mean exactly. However in this particular case I doubt anyone would get an idea to use CA for this purpose. I think it's the last choice someone would make for such a repair.

But why? Won't it make the strong enough bond of the two wood pieces in comparison to the CA-filled crack on the clarinet?

So, re-arranging the question the other way round: if you had the clarinet completely split in two halves along the length would you use Titebond to glue two parts together instead of CA?

Now, please explain to me how CA *actually* works in application to wood. Is the repaired crack strong as much as the CA layer itself? What I mean by that: assuming the CA penetrates into the wood surface on both sides of the crack and grips the wood grain firmly enough what force one needs to apply to break that joint?
In other words in this case when strong enough crack opening force is applied will the CA-to-wood link break or will the CA layer itself break?

I also want to note that in the case of "glueing" two separate wood pieces together when using Titebond clamping would be required but with CA I never hear about clamping regardless of whatever repairs are done with it.

Also I've read that the CA is useless in the attempt of glueing two different wood parts together: it won't work because the two different parts cannot be joined together close enough. Actually that's why I used an example of the wood piece split into two separate halves: they would perfectly meet for CA application.

But, wait... when you are glueing or... filling? the clarinet crack aren't the walls of the crack far enough apart from each other to take their matching surface into consideration at all?
So, back again: is it filler or glue in this case? Why does it work to bond the two clarinet crack walls that are quite far enough from each other and doesn't works at all for bonding two separate pieces of wood accordng to the warning I've read even when you use clamping which would actually force the two pieces of wood close to each other?

And now... I want you to help me with the following provided you've read up to this point - hope someone is still with me :)

I have a lute pegbox that has a hairline crack that goes into the peg hole. The crack is closed and tight and is a result of the shipping accident. It looks like at this point it does not present much of a problem but I want to repair it and make the crack glued or... filled with CA?

Please refer to the picture (it's actually a wood crack that goes all the way through, not simply a finish crack I can open it up a bit). The pegbox wall thickness is about 7 mm. Your answer will help me to make a decision whether to use CA for this purpose or use something else. Why CA? Because I can temporary open-up the crack with a "taper" a little and run CA into the crack. No other glue will do that. Then I remove the "taper", the crack closes itself and stays glued or... filled? How strong will be such crack repair?

In other words at this point you probably understand the purpose of my treatise above. How strong will be the crack joint repaired with CA provided the peg opening action is applied in normal way?

Compare it to the clarinet crack repaired almost in the same manner provided the similar psi is applied to the clarinet crack under the crack opening force. I assume the force that is applied to the clarinet crack glued or... filled? with CA is well comparable to the peg applied to the peg hole.

In both cases with the clarinet crack and the pegbox crack the cracks will be under some constant load.
So, what do you think? Will such a repair hold up on the pegbox?

Thank you for reading if you got this far.
 

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#2 ·
Easy.

A a string repairer as well, I think I can explain it for you.

Glue is not used as a filler, it does not have the strength, glue needs to be absorbed into the wood and clamped tight to allow minimal gap, anything with a gap will not seal or have strength the moment the joint is loaded.

Be that fish glue, ca, titebond, hide glue.

If a gap exists and you need some form of strength, then you need to use an epoxy
 
#4 ·
I don't think it is quite that easy. The OP's post was a bit long and I may have fallen asleep and missed a key point, but the key points seem to be why choose CA glue over tightbond type carpenters glues for gluing timbers and what are the mechanical properties of the glue.

My 2 cents worth...Although stringed musical instrument makers use a variety of glues to fabricate instruments One of the reasons CA is not chosen over hide glue or even casein type glues is that the latter types are more easily reversible for repair to the instrument. If I want to take a violin top off I hope the maker used hide glue. Another is of course tradition. On a cracked clarinet, there is no expectation of disassembly so CA is OK. In stringed instrument making as well as furniture making casein type glues are used successfully because the joinery is precise and tight fitting. Carpenters glue joints are very unstable when the joints are not mechanically tight. The glues adhere to the pores/cells in the wood. In a cracked clarinet there is often not a tight joint that can adhere the two surfaces. A tip I learned from a furniture builder was to wipe the surfaces of oily woods, rosewood, purple heart... with acetone to remove the oils before applying glue. As far as glues not being fillers , maybe this is semantics, but glues are often used as fillers, they become less of an adhesive and more filler the bigger the joint space is. Kinda like magnets the further the distance the less the attraction. So, sometimes CA is an adhesive when the joinery is tight and sometimes CA is a filler when it is not, like when you fill a crack or inlay some abalone with some wood dust and CA.

Almost fell asleep during my post. There is much more to pontificate on, but I'll quit here.
 
#3 ·
The CA is harder than the wood when it dries. But its not a strong because wood in layered and has grains. CA would probably work just fine for a crack that has not opened up, but I would be concerned about adherence especially if the wood has been oiled recently.
 
#5 ·
Random thoughts

1. If I am gluing to separate pieces together, then I would not consider CA because it may set before I get the pieces correctly aligned or clamped.

2. Because mpingo is such a hard, dense timber, I believe that white glue would be less effective. Just like you would not use white glue for gluing metal. It relies on evaporation in order to cure, and that evaporation will be very, very slow into mpingo. How would you know when it had actually set?

3. White glue seems to shrink a lot more as it dries than CA, which shrinks more than epoxy, which doesn't shrink much at all. When used as a filler, this is an issue.

4. Very low viscosity CA is fantastic for wicking into a crack far deeper than you well ever get another glue. This is good.

5. Low viscosity CA is poor as a filler, but in a narrow crack, one can just keep applying it, tiny drip by tiny drip, until the crack is filled. In a wider crack it would take too long, so wood dust or chips to the rescue, as a filler, bonded by CA. And I reckon this is as strong as the surrounding timber. I use this for the top (only) of wide cracks; it could never get intgo the narrow regions. I first wick CA into the narrow nether regions of the crack.

6. On timber, I imagine a glue is only as good as how well it seeps into the surface layers. I imagine that the low viscosity CA would do this well, providing it is damp or oily.

7. I use acetone or white spirits (Pegasol AA) to clean a crack before glueing unless it seems unnecessary. I wick the solvent in, then before it evaporates, blast it out with compressed air. So repeated, this becomes a process of progressive dilution of contaminants in, I believe, the fastest way possible. Never use acetone on plastic anything, nor where the integrity of the surface finish may rely on a die or polymer coating.

8. I reckon slow setting epoxies, especially if used with gently heat (from a nearby incandescent bulb) to reduce the viscosity, seep in well. The time factor allows it. I would not trust fast setting epoxies.

9. I think slow setting epoxies, and low viscosity CA, are both good at adhering to a timber surface. Probably as good as white glue. After a well-prepared and executed glue job, I think the timber would split nearby before the glue failed. I think this also applies when a CA + wood dust filler job is well done, without porosity.

10. On clarinets with wider splits, I sometimes use epoxy (slow setting) coloured black by black paint pigment powder (probably an iron oxide or manganese dioxide) - a tiny amount - not enough to be called a filler - and sometimes CA with wood dust. Both seem to work equally well. But:
- If the cosmetics of the area will not cope with CA attack, then I don't use it.
- If I use epoxy, I first place Sellotape along the sides of the crack to make the following clean-up easier. I use a finger - with finger clot or glove finger protection if you wish) to firmly massage the glue deep into the crack.

In your case, I doubt the crack needs cleaning. I would force a sewing pin or needle through the crack to part it a little. I'd use the Sellotape. I'd massage slow setting epoxy right through the crack until it appears on the other side, starting from where the crack is narrowest. Then take the pin out, and in this case - because it is not a clarinet split so you can - clamp it lightly (just to minimise the eventual width of the crack, for cosmetic reasons.) Put the surplus epoxy in the fridge. Put the glue job close to an incandescent bulb for warmth. When the oozed glue on the instrument is is no longer liquid, check for any gaps and touch them up with glue from the fridge, and leave that glue from the fridge under the lamp too. When it is firm but not hard, that is the best time to cut away any significant glue surplus. When cured, clean up the area with whatever tools are suitable, with the tape aiding in protecting the surfaces until the job is almost complete.. A small chisel made from acrylic is useful.

Or if this is a softer wood I might use a pin as above, and maybe the Sellotape, and use white glue, again forcing kit right through with my massaging finger.

I suppose the reason I would use the epoxy is that I have no experience of using white glue with harder, less absorbent timbers.

As with all craftsmanship, the effectiveness is in the detail, and I may well have left some out. And other craftsmen will do it differently. I doubt there is a best, and I certainly would not place bets on any particular good method not failing in an environment where the joint will be heavily stressed in normal use. If my job failed, I think I would re-glue and put a hidden, threaded pin through the timber.
 
#6 ·
Thanks everyone for you thoughts! Yes, sorry for my long message. I tried to re-read it now and almost fell asleep as well.

Gordon, thanks for the collection of "random thoughts", they are more systematic than my original essay.
Regarding your "If my job failed, I think I would re-glue and put a hidden, threaded pin through the timber.". Actually I was going to install the threaded pin anyway: to drill a blind hole and then hide it.

So, anyway, why wouldn't you use CA for this crack repair? I can only open it up just a very little, I doubt I could force any amount of any substance into it even in the "open state". The crack is quite tight and to open it a tiny bit I need to apply substancial amount of force. The question you might ask: Why would you want to glue it then at all?
That's only to stabilize the crack. Perhaps the pinning on it's own would do well but I want to do my best. Hence all that long meditation on the CA qualities because I see in this particular case it's the only substance that will go in.
 
#8 ·
.... Regarding your "If my job failed, I think I would re-glue and put a hidden, threaded pin through the timber.". Actually I was going to install the threaded pin anyway...
I likely would too. Then I could guarantee my work.

So, anyway, why wouldn't you use CA for this crack repair?
1. I would want the end result to have the crack pretty much closed, so I would expect to close the split after getting glue into it. CA has a habit of setting too fast... If you have teh crack open enough for it to get in, then it wick to the narrow part first, then set, holding the split apart, before you get the rest of the job done.
2. It could easily make a hell of a mess of the finish on the timber.

I can only open it up just a very little, I doubt I could force any amount of any substance into it even in the "open state"...
I use this pin method on split clarinet tenons. I'm sure they would be a lot more resistant to opening than your work piece. With repeated massaging with a finger, I reckon I get glue through about 0.02 mm width of crack. (Less than 1 thou) Try it on some other timber. Perhaps warm the epoxy a little first to reduce the viscosity.

The crack is quite tight and to open it a tiny bit I need to apply substantial amount of force.
Then apply it. That is not a problem as long as that force is not enough to make the split lengthen.

The question you might ask: Why would you want to glue it then at all?
1. Especially in this location, where you need a tight fit with the peg so that the peg doesn't loosen and turn, you want the timber surrounding the peg to be a stable as possible.
If you just pin, then the sides of the hole are away from the pin hence not so stable, allowing the sides of the hole to "bow" apart under the pressure of the pin, hence not providing tightness for the peg.

2. That means you are expecting the threads of the pin engaging with the surrounding timber to carry the entire load that was once carried over quite a large surface of timber. Why push your luck? Pining ha sits precarious aspect as well. At one extreme, a threaded pin is put through a non-threaded hole, matching the major diameter of the thread. You are relying totally on the bond of the glue with the timber, over a relatively small surface area. At the other extreme, you make the hole the same as the [/QUOTE] diameter of the thread, and then wind the rod into it (perhaps shaping the end of the rod so it cuts a little), so that the thread is really tight in the timber. No glue needed. Teh somewhere in between - say cutting the thread with a tap - is actually not so wonderful either, because there is not room for glue, but the thread is not a tight fit. So the thread does not actually support the timber until the split actually starts opening a little.
 
#7 ·
Its interesting.

Rosewood loves superglue, superglue bond on two pieces of rosewood is far stronger than yellow glue(titebond)
Maple - Mahogany which most musical instrument necks are made from are great for yellow glue(titebond).
Spruce - Western cedars etc love Hide glue.

All can be interchanged, all have positives and negatives, there are also more glues out there like epoxy glue, fish glues etc,

Now that being said, the picture is a cross grain crack with a load point, so its going to need a little bit more re-inforcing than just glue

Heres some wood breaks, sometimes wood can be just be glued, other times dependant on the load and type of crack, some form of re-in forcement may be required

http://www.mirwa.com.au/Cracked_Headstocks.html

and some more

http://www.mirwa.com.au/Just_Headstocks.html

Ask away

Steve
 
#9 ·
Gordon and simso - thank you for your last replies. I very much appreciate your participation in this discussion that is very loosely concerned with 'wind instruments' (unless we consider the top of the lute as the air moving surface) and at this point I can say that you already delivered your best.
I placed a similar question on the Maestronet forum (mostly violin luthiers there) and the first responses are in line with what you suggest. I'll see what else luthiers may suggest but one of the first things that was mentioned was using of the bushing of the peg hole area. That technique is often used for violin pegbox cracks and there are very detailed instructions here:
http://psi.samedisclients.com/reinforcing-a-cracked-pegbox-wall-with-a-carbon-fibre-bushing/

I actually already knew about that method by searching the web but I was hoping I could come up with something simpler. However I realize that it's quite difficult to keep the crack under the peg load stable and to guarantee it will not re-open.
 
#11 ·
Chris, that's what I was thinking about also and Gordon confirmed it. I now receive a bunch of diverse advice on the Maestronet and for some reason pinning is not so often mentioned in the luthiers' posts. I'm still collecting information for the easiest solution that should provide enough strength to the cracked area when it's repaired.
 
#12 ·
There is nothing wrong with pinning.

I've rebuilt many a cello and violin pegbox and used pins to keep the repair cost down

Maestro net has a lot of people that say they are luthiers, but in reality there just guys doing stuff at home, anyone can call themselves a luthier, just like anyone can call themselves a repairer.
 
#13 ·
Good point, simso! However many over there have links to their workshop sites (unless they are mearly virtual workshops :) ).

By the way, is pinning you used of the same threaded wire type used on clarinets or anything else like glued-in wooden pins?
 
#14 ·
Yes, workshop sites, usually you can see a shed roller door in the background, very few people around are set up for commercial work, a lot of people make a musical instrument or two, and are very vocal on how to do things, but its few and far between them (1 instrument a week / month or year) and guys that repair 5-10 instruments a day.

To repair a pegbox, be that cello violin lute old classical guitar or so forth, you have options based around cost and end result

You also have to understand the type of crack and load it may be subjected to again


In your situation, provided the neck and box are still ridgid and that crack does not form part of a larger issue

The cheapest repair is to glue the joint up with yellow carpenters glue like titebond,. then insert two threaded rods at opposing angles to prevent further splitting of the damaged area, the holes created by the rods can be hidden by making a small plug. Time to undertake repair is approx 10 minutes, cost from someone like me would be $25

The next repair IMO is to glue the joint back up, then machine / remove half the thickness along the length of the pegbox external edge, then make and fit a replacement piece of wood and graft it on. Approx repair / manufacturing time 1hr 20mins, cost from someone like me would be $75

The final way is to cut the headjoint off and remake a new pegbox and re-attach to the freshly cut surface. Approx / repair manufacturing time 2hrs 30mins, cost from someone like me would be $125

Theres many ways to carry out the repair, the limitation is your skill set and approach

Steve
 
#20 ·
Steve, thanks for a detailed answer. You know, I've been considering all three options even before your reply. Of course, since I'm not a tech but only a DIY-guy I consider the simplest option first.

Yes, workshop sites, usually you can see a shed roller door in the background, very few people around are set up for commercial work, a lot of people make a musical instrument or two, and are very vocal on how to do things, but its few and far between them (1 instrument a week / month or year) and guys that repair 5-10 instruments a day.

To repair a pegbox, be that cello violin lute old classical guitar or so forth, you have options based around cost and end result

You also have to understand the type of crack and load it may be subjected to again

In your situation, provided the neck and box are still ridgid and that crack does not form part of a larger issue

The cheapest repair is to glue the joint up with yellow carpenters glue like titebond,. then insert two threaded rods at opposing angles to prevent further splitting of the damaged area, the holes created by the rods can be hidden by making a small plug. Time to undertake repair is approx 10 minutes, cost from someone like me would be $25

The next repair IMO is to glue the joint back up, then machine / remove half the thickness along the length of the pegbox external edge, then make and fit a replacement piece of wood and graft it on. Approx repair / manufacturing time 1hr 20mins, cost from someone like me would be $75

The final way is to cut the headjoint off and remake a new pegbox and re-attach to the freshly cut surface. Approx / repair manufacturing time 2hrs 30mins, cost from someone like me would be $125

Theres many ways to carry out the repair, the limitation is your skill set and approach

Steve
 
#15 ·
CA is not a permanent adhesive. It breaks down over time, and it's not a long time. All CA joints should be considered temporary.

Another problem with CA is it is almost impossible to clean it off once applied, especially on wood, where if it fails, it will make subsequent glue joints a major problem. It wicks into the wood and does not sand well.

Epoxy is adversely affected by acetone residue. Joints to be glued with epoxy should not be cleaned with acetone. MEK is better.

Did I mention that CA sucks. It should be only be considered for very specific uses, not a multi-purpose goto adhesive.
 
#17 ·
Only about 20 years using the stuff. I also use cellulose, aliphatics and epoxies for various applications. I use CA only as a temporary emergency repair, but like I said, it makes subsequent proper repairs much harder on wood.

It had a very low shear strength, so it doesn't hold parts together well. Over time the bonded parts will eventually fall apart almost on there own.

It is very brittle. You can add filler to it to fill cracks, but like I said, sanding it is nearly impossible and whatever is around it will sand first.
 
#18 ·
Only about 20 years using the stuff. I also use cellulose, aliphatics and epoxies for various applications. I use CA only as a temporary emergency repair, but like I said, it makes subsequent proper repairs much harder on wood.

It had a very low shear strength, so it doesn't hold parts together well. Over time the bonded parts will eventually fall apart almost on there own.

It is very brittle. You can add filler to it to fill cracks, but like I said, sanding it is nearly impossible and whatever is around it will sand first.
Thanks. My own observations over a bit more extended period are significantly different in terms of bond degradation- essentially done in the applications I've used it for. This includes wood joints in model airplanes as well as plastic to metal bonding (the tach needle on my old motorcycle- done circa 1979 and subject to a lot of vibration and temperature swings). And many clarinets and wooden flutes.

It is, of course, not the best adhesive for all applications- but when it's good it's very good.

As for sanding; while it's generally harder than surrounding surfaces, careful workmanship can blend a CA repair in a pretty wide crack- filled using ground wood powder and CA in progressive fill/saturate cycles- so that the only way to detect the repair is by the absence of wood grain in the area. The reflection off the surface will appear as though there is no repair there. Just takes technique via practice and care.

As with your own take, simply personal observations.
 
#19 ·
Understood, but there are very few applications where CA is the best choice. It's frequently the easiest, but rarely the best.

I do model airplanes too, of the rubber-powered variety including indoor duration. I'll use CA to harden a balsa surface i.e. on a noseblock, but never to glue parts together. It's just too heavy and the extra weight is unnecessary. Cellulose and aliphatics give off their solvents and lighten considerably. CA, like epoxy, just catalyzes and retains all it's mass. That's what makes it a reasonably good filler, albeit with some solids added.
 
#21 ·
I made a coconut shaker by cutting it in half, cleaning it out, adding buck shot and gluing the dressed shells together with CA.
That was 20+ years ago.
I play it regularly and have dropped it several times with no ill effects.
Coconut is a very dense and brittle material with little absorbing abilities.
 
#22 ·
http://en.wikipedia.org/wiki/Cyanoacrylate

Cyanoacrylate glue has a low shearing strength, which has led to its use as a temporary adhesive in cases where the piece needs to be sheared off later. Common examples include mounting a workpiece to a sacrificial glue block on a lathe, and tightening pins and bolts.

Most standard cyanoacrylate adhesives do not bond well with smooth glass, although they can be used as a quick, temporary bond prior to application of an epoxy or cyanoacrylate specifically formulated for use on glass.[


Thin CA glue has application in woodworking. It can be used as a fast-drying, glossy finish. The use of oil (such as boiled linseed oil) may be used to control the rate at which the CA cures. CA glue is also used in combination with sawdust (from a saw or sanding) to fill voids and cracks. These repair methods are used on piano soundboards, wood instruments, and wood furniture.

Good for filler, but not holding wood parts together.

CA also has a very short shelf life. About a year unopened and only a month once opened. Refrigerating unopened bottles helps, but is not recommended for open containers.

BTW, can you tell I loath the stuff?!
 
#23 ·
CA in any form would be bad for filling/fixing cracks in piano soundboards since they are cover large areas and absorb/disperse moisture from the air which makes them swell or contract constantly.
I use it for gluing fairly ridgid pieces together.
I have a couple of bottles (thin & thick) that were opened last summer and still are viable.
 
#24 ·
I have a couple of bottles (thin & thick) that were opened last summer and still are viable.
I disagree.

CA in any form would be bad for filling/fixing cracks in piano soundboards since they are cover large areas and absorb/disperse moisture from the air which makes them swell or contract constantly.
But I agree with this. CA is bad for a lot of things.

I do a lot of gluing and the only thing I use CA for is where its wicking properties come in handy. I make little spoke wheels and use it to glue the two pieces of aluminum hub together and attach spokes to hub. It's convenient because one drop will wick all the way around.

 
#26 ·
By the way, getting back to the original subject of using CA for filling (or glueing?) the wood clarinet cracks. What does CA actually do? Fills the crack cosmetically or holds it tightly to prevent further opening of the crack?
Many insist CA will hold the crack from further expansion forever once repaired that way.
 
#28 ·
I think filling a wood crack, and holding the wood from cracking more, are two different issues.

If the clarinet has migrated from its past life in humid FLA to its new home in dry Arizona, you are never going to stop it from cracking until it reaches its stability point. If wood wants to expand or contract, it's going to do so and there is nothing you can really do to stop it. Even if the CA was strong enough to hold the two edges of the crack together, a new crack will simply start adjacent to it. I suppose you could band it, but glue won't do much.

Now if the wood is stabilized and no longer contracting, then you can just fill it. But why use CA for this? It's messy, doesn't sand well and leaves a shiny scar. Better to mix some grenadilla dust and yellow glue for fill. It would sand to an invisible repair. And if it does open again, you can simply remove the old glue and repeat. Once you put CA on it you're done. You are never getting it out of the joint.

Different horses for courses, but I wouldn't use it to fill a wood crack in a clarinet.
 
#31 ·
I think filling a wood crack, and holding the wood from cracking more, are two different issues.

If the clarinet has migrated from its past life in humid FLA to its new home in dry Arizona, you are never going to stop it from cracking until it reaches its stability point. If wood wants to expand or contract, it's going to do so and there is nothing you can really do to stop it. Even if the CA was strong enough to hold the two edges of the crack together, a new crack will simply start adjacent to it. I suppose you could band it, but glue won't do much.
I think the subject has been covered in earlier posts. If you do a search you might find some hints concerning the matter. One thing you can do to avoid the disadvantages when moving from one humid are to an assumingly other dry, is to keep the instrument in a protected area. After you´ve played it, just wrap it and always keep it in a plastic bag. How about that?
(Sorry for stealing the subject, it was unintentionally. Supposedly the original question was answered.)

Best regards
 
#27 ·
Some people like it some dont

In an earlier post I referred to, I mention rosewood loves ca. Super strong

For grenadilla I use ca, holds just fine.

You need to understand the type of wood you are repairing, it's load structure and it's associated grain strength and direction, knowing this can allows you to pick an appropriate gluing medium.

Example if I cut a scarf joint when making a guitar neck, I would not use ca to join the two pieces of wood together, hide glue would be the strongest for the load, but I wouldn't use it either, I would use yellow glue for its convenience and longer setting times, even though yellow glue has creep in comparison to hide glue, the creep doesn't occur until subjected to loads far greater than that, that can be applied by a set of strings

Where as a clarinet with a crack has really almost no load, but we need to be able to join a split grain line back together, so in this instance ca is perfect, it has excellent wicking capability, is strong enough to join the grain and can also create a water / oil proof boundary layer
 
#30 ·
Even when we know our approach is good, it's often difficult to analyse exactly why we have settled on that approach. I'll try:

Glue or filler - what you call it is pretty much arbitrary depending on hw wide the gap is. For instruments, typical would be say 0.2 mm at the widest, though some would be closer to 1 mm. Pretty well all splits on instrumnets taper off from their widest pat to nothing, in a linear sort of way. Any glue filling any of that gap could be termed a filler.

Sure, I agree that a crack is pretty much stable after it has opened. (My only concern really after filling really is that if the clarinet was later in a situation where the timber was quite damp on the outside but not on the inside - pretty unlikely - then the glue filler in the wide part would stop that wide part from shrinking, hence strongly encouraging that split to continue right to the bore, where it is unseen and difficult to deal with).

But as with the rest of the timber, it is never fully stable. There will always be stresses. As long as those everyday stresses do not get to the point of splitting the timber nearby, I would prefer that the glue/filler joint be as strong as the resistance to splitting of the timber itself. Otherwise the split reapir wouild be more inclined to open than it otherwise would.

Therefore I get the glue to do the best it can. That means covering as much surface of the split as possible. That means wicking right down (still as a gap filler) to the narrowest parts of the split. CA is the glue that does this best.
Unless the split is wider than typical, there is no need for a wood-dust filler. Indeed, that is not likely to penetrate a 0.1 mm gap at all. As long as it is not over-polished, CA can match the timber very well in a narrow gap.

If the split is a bit wider, then I might still use CA because it wicks to the narrowest parts of the split. But keep adding more until the spit is filled. Wider still, and I also use grenadilla dust with CA as the binding agent. The CA is not being used as a filler. It is a binding agent. It is the glue that holds the particles of dust together, in gaps that are very, very small. It is strong! Almost certainly stronger than the timber.

For me, the big case against CA is that is very destructive to the thick grain-filler often applied to ll but the most expensive clarinets. This is often quite thick, almost like a mat lacquer. It is really difficult to effectively touch-up after CA has attacked it.

So for splits in these bodies, this cosmetic issue may be the over-riding factor. So I use epoxy. It is strong as both a glue and a filler. Its downside is that it does not wick well at all, so I massaging it deep into even 0.1 mm gaps using a finger, as I think I explained in another post. I usually add a trace of extremely fine black pigment powder to improve the cosmetics of the finished repair.

Yellow or white glues depend on evaporation to cure. During this process they shrink. I think the main case against them as a binder for grenadilla dust is that evaporation will be very slow, especially beneath the visible surface, and I don't want to attend to the surface cosmetically until all shrinkage has stopped. I like to get a job done quickly. With slow setting epoxy, and a light to heat it while setting, it is set hard in say 40 minutes. I think it would take maybe 20 times longer for an evaporation-based wood glue, used on this relatively impermeable material. Otherwise fine, especially if massaged deep into the crack.
 
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