Should old hide glue be removed first?

[Alexander López]

Hello everyone! I need some advice here from the glue specialists.

I have received a Michael Kelly acoustic bass guitar with a cracked peghead. Not much different from the classic Gibson crack, but here's the skinny: it was repaired using hide glue -and failed.

I guess I could use cyanoacrilate glue, since its lower viscosity can reach deeper into the crack, but I'm afraid it won't stick to the wood but to the failed hide glue instead. Is there a way to remove the old hide glue without damaging the binding? Can I just use cyanoacrilate? Or should I use hide glue again? Thank you!

[Jim Bancroft]

If you are going to reglue it with hot hide glue you do not need to remove the old glue. I'd run some warm water in the crack, flex it, and make sure it completely closes. Then I'd open it and work more hot hide glue in. Make sure it is thin and works it's way completely into the crack. Then reclamp it.

If you are going to reglue it with superglue. Then I would probably first heat the cracked area, run some warm water into the crack to flush out hide glue. Then I let it sit for a week to dry out, then glue with superglue.
The best I can advise, but I'd probably glue it back with thin hot hide glue

My feeling is, I prefer hot hide glue for a crack that can opened enough to get complete glue penetration. If that is not possible or highly unlikely, I'll use superglue. Thin superglue will easily penetrate completely into any cracks.

Jim

[Mike Kolb]

Before grabbing the cyano, I'd be tempted to try hot hide glue again for the repair. Here's why: since the first repair failed, there's a good chance that it wasn't done correctly. A well-applied hot hide glue repair should hold like there's no tomorrow.

Jim's right that the glue needs to be thin and that the crack needs to be flexed-open so the glue can get to where it needs to be. I'd also use a hair dryer to pre-heat the open crack, then quickly run some hot water into it just before gluing-up... take every opportunity to keep the glue thin as it works it's way in; then clamp it up and wait 24hrs.

If it still doesn't hold, you've done the best you can with HHG... and then -but only then- it might time to grab the superglue.

[Bob Webster]

Hi, Alexander. There was alot of discussion about hide glue and a cracked peghead in a previous post to this forum. You can find it at http://fretsnet.ning.com/forum/topics/peghead-crack-do-i-really. It wouldnt hurt to review what was said there as just more background on what's in front of you.

Best,
Bob

[Alexander López]

Thank you for your advice! I've read the peghead discussion and your advices, and what worries me is the risk of cracking the headstock top laminate in half. I do prefer the hot hide glue, so I'd like to do these steps:

1) Use medium-hot water to clean up the remanent hide glue.
2) Keep the headstock warm by using some hot-watered wet towels.
3) Prepare a very low-viscosity mix of hot hide glue, fluid enough to be like hot butter.
4) Use a syringe with a flexible catheter to inject the hot glue into the crack.
5) Clamp everything ASAP and keep them on during two days.

What do you think?

[Jim Bancroft]

The hot hide glue needs to be water thin. As long as it is slippery between your fingers, is all you need.
When you apply the glue, make sure you flex the joint when applying to get it all the way in.

I use a hair dryer to get and keep parts warm.

12 hour clamp time is plenty, but wait 24 hours, minimum, before you string it up. If in doubt, wait as long as you feel you should.

Jim

[Bob Webster]

Just a few more caveats, Alexander.
1. Warm the syringe with the flexible catheter in the water bath for the glue until just before you use it so that it doesn't sieze on you.
2. Stick those hot watered towels in a plastic bag. You really don't want the whole peghead drenched in water. One thing that could happen is that the peghead veneer could delaminate and then you're really in for it.
3. You might want to make the glue cleanup a separate exercise from the gluing part and give it plenty of time to dry before gluing. I'm thinking that a very wet joint with very thin hide glue might take a whopping long time to dry. It also might not achieve very good adhesion if the wood is very wet.

Beast of luck,
Bob

[Alexander López]

Hello, people! I'm happy to tell you how the creacked headstock repair went. It's a success!

I removed the old glue by placing the headstock under the tap, with warm water. Let it dry during a week, and proceeded to glue it up again.

I added a little more water to the mix of hide glue, and heated up until it could flow easily through the syringe's needle. Then I filled the syringe and kept it in the hot water until the last moment.

Before gluing up, I used a hairdryer to warm up the wood inside the cracked headstock. When applying the glue, I made sure to move the needle through the entire crack, and clamped everything. Let it clamped for a week, and after cleaning the excess glue (don't you love how easy is to clean hide glue?) I strung up the guitar.

The repair worked!! Just to be sure, I kept the guitar for two more days with the strings correctly tuned, and it remained stable. No creaks, no failure at all. Sweet!

I want to say a collective THANK YOU!! for all your expert advice, I couldn't have done it without your help. This sure is a very helpful community. Thank you all, again!

[Bob Webster]

Congratulations, Alexander! Actually, all of us were just throwing out crap to see if you'd bite.

JOKE JOKE

Cheers,
Bob