View Full Version : Ukulele Warped: Binding Cracked/Split in three areas –Any glue suggestions?

12-26-2010, 09:01 AM
There are three cracks in my ukulele, the binding crack on the back is about 1.5 inches long, the front body crack is about ˝ long, and there is another one about to split in the back. I want to repair it myself. What type of glue should I use that would not damage my solid mahogany uke? How can I prevent more cracks from forming besides using humidifiers?

12-26-2010, 09:26 AM
How did these cracks come about? Is it impact or too dry?

If it's too dry then the only way to stop them from happening again is keeping the instrument from drying out to much and too fast. How you go about that you can figure out.

If those cracks are from drying out and are slightly open then you can hang the uke up in a humid part of the house. In the shower area is usually a good spot. (not with you while you are showering). The wood will pick up some moisture and swell up, closing the cracks. Then the only glue that I'd use is hot hide glue. If you don't know what this is, or how to use it then you've got some research to do. A good place to start is on Frank Fords (http://www.frets.com/FRETSPages/pagelist.html) site.

Here's one page on Franks site that might be some help if the cracks won't close up. Crack inlay on ukulele (http://www.frets.com/FRETSPages/Luthier/Technique/Ukulele/UkeCrack/ukecrack.html)

12-26-2010, 12:18 PM
Hi Allen,

Thanks for the tips. I will check out the sites and tips you suggested. Regarding the cracks, my room is too dry and the heat may have damaged it even with three humidifiers stored in my case. Perhaps the uke started cracking when I took it out of the case to play. I want to try the hot hide glue you suggested but I have to research what it is first. Is the hot hide glue safe for solid mahogany wood and tortoise shell binding?

Liam Ryan
12-26-2010, 12:58 PM
hide glue is safe and recommended for Mahogany and although it may or may not glue tortoise binding I'd be absolutely blown away if it damaged it.

12-26-2010, 01:22 PM
Thanks, liamfnq.

12-27-2010, 05:54 AM
You say on the other thread that it's the binding which is "cracked" - do you mean it's coming away from the body of the uke?

Pictures would be a *huge* help.

If it's plastic binding coming away from the body then hide glue is not what you want. The glue most commonly used to stick bindings on is Duco cement. You will face two difficulties:

1. Getting the glue into the space between the binding and the body. Maybe a thin knife blade? Once it's in there, you can use PVC electrical tape to clamp it until the glue is dry - this tape has stretch in it so it will be good for the job, and comes off cleanly.

2. Cleaning up the glue which squeezes out from the join. I've not yet worked with Duco - am about to start my first binding job - but when you're building a uke you glue the binding on before finishing it. The bindings need scraping down to the profile of the body, and you can scrape away the dried glue during this process. You will have glue on top of your finish, and I'm not sure what to recommend here - certainly mask off the body with masking tape, and I guess carefully scrape off the squeeze out with a razor blade. Anyone have experience and better ideas?

If you actually have cracks in the body of the uke, then hide glue is the way to go. Pictures will tell us how bad the cracks are, whether they need some reinforcement, etc.

12-27-2010, 07:56 AM
Hi ProfChris,

Unfortunately, my camera is not working and I can't show you any pics. No, the binding is made of solid mahogany, not plastic. The cracks are coming away, splitting from the binding, forming gaps that needs to be sealed. The cracks are getting bigger. So, would hide glue stilll work or do I need to use Duo cement? Thanks.

12-27-2010, 09:22 AM
Do not use Duco cement on wood bindings. It's only meant for plastic. Also this glue acts by "melting" the plastic a little to help with the bond. So if you are going to need to use it for plastic binding you need to take care. It also swells the binding until all the solvents dissipate so you need to let it sit at least overnight before levelling it.

Hot hide glue is safe to use on all wood. It is worked at 140 - 150 degrees F so will not melt anything. It's totally reversible and cleans up with water. At that temperature the glue should have the consistency of thin maple syrup. It will run into cracks and you can work even more of it in by rubbing your finger over it. As it dries it pulls the joint even tighter together. It's got to be a good joint to start will, as it Will NOT fill gaps.

Did you just get this ukulele, or is this the first winter (I'm assuming winter were you are) it's gone through? Do you know what the relative humidity is in your home? No instrument is going to do well if it was built at 40 - 50% RH and then subjected to <20% RH.

12-27-2010, 10:32 AM
I was concerned to read that you have three humidifiers in your case. Too much humidity can be worse than not enough, and moving the instrument back and forth between wet and dry environments can wreak havoc. One case humidifier, carefully monitored with an accurate hygrometer, should be plenty.

12-27-2010, 11:57 AM
Allen, thanks for the clarification about the Duco cement. I will get the hide glue you suggested. My uke is not plastic; it's made of solid mahogany, including the tortoise binding. You mentioned that the hide glue will not fill the gaps, but I hope it will at least seal the binding. I purchased the uke a year ago from Hawaii, there were cracks in several spots when I received it on Christmas and I had to exchange for a new one from another retailer, and received this one in April. Yes, it is winter here in NYC. We had a major snowstorm. I don't know what the relative humidity is in my apt. I need to find out.

12-28-2010, 02:47 AM
it's made of solid mahogany, including the tortoise binding.

If you have tortoise binding then it's almost certainly plastic (the binding, that is). Unless it's a vintage uke, when I guess it might be actual tortoise.

For wood/wood bonds, hot hide glue is tops as Allen says. For wood/plastic bonds I think you need Duco.

Can't you find a friend with a working camera and post us some pictures? I'd hold off ordering glue until we are sure what the problem is.

12-28-2010, 09:15 AM
Yes, at the time of purchasing the uke, I was told that the tortoise binding is made of solid maghagony. Unfortunately, I still can't get anyone to take any pics. I'll hold off ordering the glue, but I hope the cracks will not get even bigger as the days go by.

12-28-2010, 10:14 AM
I can't see how solid mahogany binding would be considered tortoise shell. It's either one or the other. Does it look something like the stuff in the link (http://luthierssupplies.com.au/product_info.php?cPath=182_183&products_id=530)? If so then it's plastic....or perhaps the real thing if its a vintage instrument.

Liam Ryan
12-28-2010, 12:45 PM
If it's real tortoise shell we may need to find out what tortoises glue their shells on with?

12-28-2010, 12:53 PM
First, if it's just the binding coming loose, don't panic. Even if all the binding fell off, the rest of the uke would stay together and not suffer (unless you knocked it hard against something). All the seams are reinforced on the inside (if you look inside the soundhole at the seams where the back joins the sides you will see what looks like a series of little wood blocks. This is a strip of "kerfing", which is a slotted strip of wood glued to bottom and sides. The same is under the top seam.) Carry on playing the uke unless there's a danger of breaking the binding strips while strumming. If you want to protect the loose binding from knocks stick some tape over it (electrical insulating tape is good because it won't leave much in the way of sticky residue and is a good solid shield against knocks).

If I've misunderstood you and there are cracks in the wood of the top, back or sides then this is (potentially) more serious, but again don't panic. Monitor those cracks - if they grow, slacken the strings and stop playing until they are fixed.

Finally, if you plan to make the repairs yourself there are two kinds of repair. The first is the kind I used to make in my youth, which is hurried, ugly and might not fix the problem. The second is the kind I try to make now - this takes time, thought and slow working.

As you have a solid mahogany uke with tortoiseshell binding (even plastic tortoiseshell) it's probably quite a decent instrument and deserves the second kind of repair.

So, don't panic, keep playing if it's merely binding coming loose, and post pictures. The experts here can then explain how to fix it yourself without damaging the uke in the process.

12-28-2010, 01:16 PM
Allen, I can't see the pic from your link. Like I said, I was told mine is a solid mahogany.

12-28-2010, 01:23 PM

Yes, the binding is open, and you could see the gaps and I want to seal those gaps. Indeed, it's a lovely instrument, and deserves to be treated with extreme care. The cracks have been growing bigger, as I have been monitoring it. I'm worried that if I don't repair it now, the cracks would get more bigger.

12-28-2010, 01:52 PM
Allen, I can see the link you sent me now, it looks a little like it but was told mine isn't plastic, it's solid mahogany.

12-28-2010, 04:22 PM
It sounds to me like the Uke needs humidity. The cracks are going to continue to grow unless you stabilize it. The cracks may even close up some if you do this. It takes a few weeks in a tight closed case with careful monitoring. I would not worry about the binding until the body is stable.

12-28-2010, 04:44 PM
Allen, I can see the link you sent me now, it looks a little like it but was told mine isn't plastic, it's solid mahogany.

The body and neck are probably solid Mahogany. Could the "real wooden Mahogany Tortoise Shell" binding be Snakewood? It looks a lot like Tortoise Shell. Here's what it looks like:

12-29-2010, 08:38 AM
Tarhead, I called the uke dealer, and was told that the binding is not made of solid mahogany. I was mislead by the retailer who I bought it from. Well, the dealer said he doesn't know what the binding material is. I asked if it is made of plastic, he said no, but it is closer to hard plastic. Also, he doesn't know what type of glue I need to use. I just want the cracked binding along the edges to be sealed, and find the right glue for it. I think my uke needs humidity to get it stablized, too.

12-29-2010, 09:49 AM
I think my uke needs humidity to get it stablized, too.
Sounds like... it needs to be checked into the "Uke Baby Clinic" and put into an incubator ASAP.:):)

12-29-2010, 12:40 PM
I use weld-on16 on tortoise Shell binding you can get it at Stewmac

12-29-2010, 12:45 PM
bluesuke. is the weld-on 16 glue safe for solid mahagony? The cracks are along the edge of the binding and body of the uke.

12-29-2010, 01:15 PM
yes its fine on all woods

12-29-2010, 01:16 PM
Tarhead, I called the uke dealer, and was told that the binding is not made of solid mahogany. I was mislead by the retailer who I bought it from. Well, the dealer said he doesn't know what the binding material is. I asked if it is made of plastic, he said no, but it is closer to hard plastic. Also, he doesn't know what type of glue I need to use. I just want the cracked binding along the edges to be sealed, and find the right glue for it. I think my uke needs humidity to get it stablized, too.

Well all right then. Get some Weld-On 16 Cement http://www.stewmac.com/shop/Glues,_adhesives/Weld-On_binding_adhesive.html for the binding but wait to fix it until you are sure the body is repaired well. Don't freak over what you're seeing between the top or bottom and the sides. That's the kerfing used to attach everything together and should have holes in it. It should look like that.

I'm assuming you are using a gig bag for a case. Get a plastic storage bin with a tight fitting lid just big enough for the Uke (The red and green ones are on clearance now after Christmas) and put the uke in it. Get a Planet Waves Humidity Control System http://www.planetwaves.com/PWHumidity.Page and put that in the plastic bin not touching the uke. Seal the bin up well and ignore it for 3 weeks. Once the cracks are stable you'll need to deal with them as recommended earlier. I would add you could heat the cracked area to keep the hide glue in a liquid state longer. This will assist with deeper penetration of the glue into the crack.

Now that the body is repaired you can spread a thin film of Weld-On cement in the channel and clamp the binding with some 3M #233 Green Masking Tape. Check an Auto Parts store for this. I get it at NAPA. I like it because it stretches a little and applies tension to the edge. When dry you may need to fill some voids between the top or side and the binding with binding paste made with some binding shavings (order a matching piece from StewMac) and Acetone. The Weld-On and Acetone binding paste works by melting the plastic so be very neat.

12-29-2010, 01:46 PM
Tarhead, thanks. I will go check out the links and move forward to the steps you described.