I've got an odd situation here, and I'm about at my wits end. As you can see from the pic, this guitar came to me with a fractured headstock. The crack is quite fine and clamps up nicely. The problem is, it won't glue shut!
I am using CA for this. I've used the thin Stew-Mac CA for the upper part of the crack, and I've tried both tite-bond CA and Stew-Mac's medium CA for the more open part of the crack. The glue is wicking down into the crack all the way, but the crack is just not staying closed.
The guitar is an inexpensive Yamaha that is just a couple years old, I believe. The crack was only hours old when I got to it. The guitar took a dive off a stand apparently.
The titebond CA & thin Stew mac CA I have are not fresh, but I've been using them with good success on other jobs, and the medium Stew-Mac CA I opened specifically for this job.
Is there possibly something I am overlooking with this? Over the past couple decades I've glued up countless tight cracks and splinters on harps using off the shelf CA and can't ever remember having an issue.
I've tried to glue this crack 3 times over the last 4 days, leaving it clamped up for over 12 hours the last couple times. It's starting to affect my sanity...
First of all, unless that crack can be opened up, I don't think it looks all that bad given that some softer or looser grain woods react very easily to moisture. I think this looks like this may be the case here. Using Titebond will introduce some water content and can contribute to some grain swelling in the crack. It wouldn't take much swelling to force this amount of movement.
You said you have been clamping it up over and over but you didn't say if you are actually able to open the crack. If that's the case you many have a problem of the bond failing because of a foreign substance such as silicone or even old glue that keeping the new glue from actually bonding with the wood.
Maybe someone with a different take on it will chip in but if it is swelling you may just have to wait to see if it will dry or touch it up and leave it.
I think I would have gone a slightly different route with this repair. I would try to see if there's any movement in the crack (opening it up), or else manipulate it to open ever so slightly. Then glue with thin hide glue.
If you choose to use thin CA (because it's such a tight crack, and might not open up any further). I would have used the fresh thin CA for the entire crack. Medium might actually interfere with closing of the crack. (but then again, I can't really judge that, by the one picture)
Now if you've glued this tight crack for 3 times already, there's no way it's gonna close any more than this (due to the CA that is now in the crack and formed a "skin" on both surfaces). I'm sorry.
Are there any before photo's you could share with us + your clamping arrangement?
Perhaps there are some small pieces of wood in the bottom of the crack acting like fulcrums. When you clamp the crack, the wood bends around the object, but when the clamp is released the crack is forced back open.
Forcing the crack open using xacto blades or something similar as wedges, then digging out anything loose with dental picks or an xacto knife would minimize resistance to closure. You could also try to scrape out glue while you're at it.
How about a hypodermic of hot water to flush out the crack using a cotton covered blade to remove water-based glues (taking precautions to protect the finish)? You might follow this with a very thin blade wrapped in thin cotton with mineral spirits to remove silicon contamination, if any. I'd follow that with naptha, since mineral spirits is a little greasy, then go to epoxy as a kind of trump card. "Take that, you blasted crack!"
Andrew, could you link to the thread you mention?
This guitar is not worth much effort. The owner was just about to buy a new guitar instead of getting this one fixed! If there ever was a place for super glue in guitar repair, this crack should be it. It seemed to be a no-brainer. The only thing that I can imagine the issue being is outdated glue. Still, once the bad glue dries, fresh super glue should bond the crack together, no?
FWIW, I was able to use a dowel rod through the tuner hole as a fulcrum in order to flex the crack open and "pump" glue through the entire thing. From the start I had good glue penetration.
I've experienced situations where the first attempt at CA on wood hasn't been very successful. Not sure why but I think it was because the wood was very absorbent and so there wasn't much glue left on the surface for the bond by the time it cured. The second application seemed more successful, maybe because the first app sealed the grain and prevented premature absorption. For the same reason, end grain is very hard to glue sometimes with almost any thin bodied adhesive, even HHG. My limited experience with medium viscosity CA is that it bonds/seals better but is extremely easy to end up with squeeze-out.
Let's hope my theory is the reason I had to re-do the attachment of the broken head stock scroll on my mandolin.<G> Otherwise, I may be doing it again.
Larry, I think you are on to something there, as I've had that happen before as well, but with splinters that I could not clamp well. Usually the second application does the trick. Still, I've ran glue into this thing like 4 times...that should be enough to seal any open pores!
I let the crack dry overnight last night and got out my thick viscosity CA and levered that into the crack along with the medium in the really tight part. Again, the glue, even the thick stuff penetrated well in. If it doesn't work this time, I think I will just have to fill the crack with epoxy or thick CA (in layers) and call it good.
I've got an email in to Titebond hoping they can confirm that old CA loses its adhesion qualities at some point. I know I will be labeling all my bottles with an "opened on..." date from here on out.
A few suggestions.
The wide ranging differences in regional environment across a huge Continent may make some real difference to different peoples experiences in regard to this matter.
But what I would suggest is that you avoid purchasing the Larger Bottles, for economies sake, which then could be around for quite a while, long after they are opened and first used.
Instead, purchase the Smallest Bottles and then use them up far more quickly. After you open them, reseal them quickly and place them in the Freezer or at least in the Refrigerator, and that should help them a great deal to keep far better, and longer in the proper condition.
What I'm wondering about the Guitar Headstock Problem as described, is whether there is something of a drastic Lack of Moisture in the Wood.
That it is completely dried out to the extent that the CA Glue which does require a bit of moisture in the wood to adhere properly, then finds it very difficult to properly take. That would be my hunch.
I'm also wondering whether the Guitar Owner has "cleverly" kept his Machine Heads running well by Oiling them very freely with the Machine Heads still fixed to the Headstock and given the general area a Liberal Oiling, without realising it.
This by way of the Oil Travelling through and into the Machine Head Holes and penetrating the wood quite deeply in that manner, and perfectly along the line of the actual split, and from Hole to Hole. Oiled repeatedly many times over the years, there could be quite a build up, deep inside entirely unseen.
Lack of Moisture in the Wood, along with some presence of Oil deeply penetrated in the Wood, which also may look as if its dried up but still be present enough to inhibit adhesion. And these two problems compounded by the use of Old Glue that has gone off to some degree, but not yet gone thicker.
That would be my considered hunch, without ever looking at the Guitar.
I find Freezing certain things helps a lot.
We have a Factory Plant around here where a relative of mine works, close by with Cryogenic Freezing Facilities.
Cryogenically Frozen Audio Cables is an interesting area for me which some people are really in favour of, and others laugh at, brilliant folk on either side of that.
But Stockings and Tights prove they will not ladder once treated in this way, though you appreciate, I don't actually use them myself.
Happily, a Fridge or Freezer should be all you need to make a difference to the CA Glue.
But we need to educate people about how to properly lubricate Machine Heads.
The dryness of the wood may be a factor, but the oil, no, although I do see your point. I know most of the history of this particular instrument, and can rule out oil as a factor.
In all the internet research I did yesterday regarding storage of CA, all the manufacturers say you can prolong the shelf life of UNOPENED CA by storing it in a refrigerator or freezer. However, all also said that you should NOT store opened CA this way.
According to the info, once opened, condensation can form in the bottle after you take it out of the freezer/fridge to use, which will cause the glue to harden in the container. It is suggested that you let the glue warm to room temp. before using, hence the possibility of condensation forming.
Another suggestion for storing open bottles of CA is in a tightly sealed jar. I have lots of these, so I am going to try that. FWIW, I always buy the smallest amounts of glue I can, but I still end up not using much over the course of a year.
I use a plug cutter and forstner bits to get fresh wood across a crack. In this case I'd clamp the crack closed, drill a hole across the crack 1\8th of an inch deep. Cut the plug to fit, finish the plug first and then glue it in. Size and placement are dependent on the repair. It's a great technique for a bad ding in a top. I use a router to make the recess it's easier to control the depth.