Side crack gluing problem

[George Roberts]

This is the Martin tenor uke that has needed repair for the past 40 years.  The long side crack can be brought together, but only with the use of magnets, the plywood form, and small tapered wedges made out of popsicle sticks.  The problem is that there is no way I'm going to get this all back together in the working time of hot hide glue.

I see the possible choices as liquid hide glue, original Titebond, or CA glue.  Any preferences or other suggestions?

Thanks, George

[Hesh Breakstone]

Hi George - Lutherie glues are not unlike golf clubs in that one size rarely fits all.  HHG is wonderful stuff but let's also remember that the wide spread use of HHG back in the day was before we had other alternatives.

Bottled hide glue is awful stuff and not at all the same thing as good-ole HHG.  I would not use it....

My choice of the choices that you listed would be Titebond original.  It works well, has a decent open time, is reversible, easy to find, and if you check the date code and are sure that your stash is not old I'd go for it.

Don't get me wrong I really enjoy using HHG but when lots of clampage (and time) is required it's better to use something that has no chance of gelling before you want it to.

Lastly - waxed paper is your friend with either Titebond or HHG if there is a risk of gluing your instrument to the form, wedges, magnets, or clamps.

[William F.Eden]

I faver the use of CA because you can repair a little bit at a time as you clamp it up.Bill.

[Justin]

I would also agree with Hesh about using Titebond Original.... It has enough open working time to completely glue a crack like this. It also has great properties of filling in small voids in the crack. Remember to clean your hands well when using it, and DO NOT use the Titebond 2 or 3... I have also used CA in similar situations, but you must be quick with your clamping and what not and it can turn into a mess real quick.

[harrison phipps]

I like the white instrument makers glue sold by LMII for tasks where HHG is less than ideal. It drys clear and hard.

[George Roberts]

Thanks for all the help, guys.  I was feeling a little inadequate about not using the HHG.  Hesh, really appreciate your reminder about the date code.  The bottle I've been using seemed fine, not thick or stringy, but the date code is one that they don't even use anymore.  Picked up a new bottle this morning.

Harrison, I will order some of the LMI glue and give it a try.

Bill, every time that I have tried that approach with CA, it seems as though the part I have just glued prevents the next section from fitting together properly.  Probably poor technique on my part.

George

[Hesh Breakstone]

My pleasure George.

BTW I like LMI White too but have not been using for the last several years because living here in Michigan I can't get the stuff without a risk of freezing in the winter.  If it freezes it is ruined and we have had some issues with this prior.  

Good stuff, we just live in the wrong part of the country to have access to it year round.

[LARRY KLOSE]

I have a flamenco guitar that developed a couple of small, non-displaced, hairline cracks in the top below the bridge.  They open up here in dry Arizona if the humidifier in the house is off for too long.  It's warrantied and I was going to send it back to the builder but he and I talked and he suggested that before I do that (for the $70 that it would cost for shipping and missing the guitar for a few weeks during gig season), I try putting HHG in the crack when it's open, humidify the instrument to cause the cracks to close up, then warm the area with a hair dryer or heat gun to re-activate the hide glue.  If it works, no other work would be needed.  If not, it can still go back for repair.  I haven't tried this yet since the Arizona summer wet season is just finished and the crack hasn't had a chance to open up, but I may still do so when the time is right.  

Would this be a way to stabilize the larger cracks in the Uke while clamped?  Would it be possible to work the HHG into parts of the crack to stabilize, then move the clamps/ to nearby areas for the remainder and do the same thing?  Or would the clamped cracks be too tight to take enough glue in?  What else am I missing?

[Hesh Breakstone]

One thing that hot hide glue is terrible at and that is being used as a filler....  What it does best is provide a very thin, crystaline glue line that seems to be very acoustically transparent.  Not to mention the other notable qualities of hot hide glue (never the bottled stuff..) of being reversable, edible, traditional, and even fun in my view.

I don't like the methodology that the builder is advocating for repairing cracks.  Since HHG sucks as a filler and will gell very fast filling an open crack with HHG, rehumidifying and attempting to get the glue to become liquid again does not address a number of important elements for top crack repairs.  

For example, clamping a top crack to insure that it is level is often standard fare.  Where's the concern for gluing a crack in an unlevel state in this method?

Next for HHG to work well we have to be capable of having what ever clamps, magnets, etc. that we are using in place in around 15 seconds or less.  Although HHG can be reheated and reactivated most crack repairs need more than a self-closing situation to ensure a good bond, levelness, etc.

How I would approach this repair is to rehumidify the instrument (bag it....) and when the cracks are closed I would be manipulating them to get some glue in there and then clamping every thing level.  A cleat or more would be advisable in many circumstances too.

A hair dryer won't be hot enough to activate the HHG and a heat gun, unless you have one like ours with a variable temp function, is risky because you can easilly smoke/bubble/ruin the finish.

Larry if you were a builder of this guitar would you want you or I attempting to repair it ourselves or would you want the customer to send it back to you for a proper fix?  I'm asking becasue this is a new one to me, a builder telling a client to smear some HHG in there and rehumidify your home and get out the heat gun....

I'm affraid to say it's just not that simple....

[Joshua Levin-Epstein]

Jim Hamm made a presentation at the last GAL convention that was covered in  American Lutherie #109. His technique for gluing tops or backs has each gluing surface painted with HHG (which dries), aligned and then reactivated with a squirt of steam. This might be the ticket for your job.

Here's a link to his website;

 

http://www.hamstringsmusic.com/Strad%20Trade%20Secrets%20April%2008...

 

[LARRY KLOSE]

Hesh,

The builder never said he didn't want to do the repair.  I wanted to know if there was anything I could do so I didn't have to send it back--I play it frequently and gig with it so I don't want to give it up--It's a great sounding guitar.  He's ready to fix it now or later, but he suggested that I could use the glue method to see if it works.  If not, it's back to the builder.

Mentioning this has smoked out some good information on how this might be effective and most importantly, how to do it.  That's what I was looking for when I mentioned it here.  

BTW, my initial description was a paraphrased summary--there was a lot more detail in his suggestion on how to do it if I wanted to try myself.

Larry

[Paul Breen]

George,

The gel time of hot hide glue can be way improved by heating the parts to be glued. Hide glue gels at about 95 degrees so you don't have to cook the sides, just keep them so it feels good and warm to the touch. Infrared light bulbs in a clamp-on fixture work quite well and can be left on while you glue up. If you end up with HHG, make it watery thin, it will wick itself better into the crack. I like the HHG for ease of cleanup and it won't damage the finish like CA. If you use Original Tightbond, water it down some, it will increase the open time. Tightbond does not wick into tight places very well but watering it down would help that some. Regardless of the glue you end up using, you'll want to add some re-enforcement along the crack, inside of you tenor uke.

I found this picture from a bass repair I did a few years back to show you a few ways I deal with holding and aiming the infrared bulbs.

[George Roberts]

Hi Paul,  Hard for me to imagine getting all those spool clamps on and tightened before the HH gels.  Makes me sweat just thinking about it, let alone with the infra-red bulbs on.

I did use the original Titebond, and it came out pretty close.  That was on the crack that was most displaced.  The crack on the other side lines up nicely, and I'm planning on HH for that.

Thanks again for all the help, George