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mzuch
09-10-2013, 06:40 PM
I use different glues for different purposes, including hot hide glue for attaching bridges. News of a lifting bridge on one of my instruments motivated me to test the strength of a HHG bond against LMI Instrument Glue and Titebond Original. I prepared six pieces (3 pairs) of Spanish Cedar, each 6" x 1" x 1/8". I applied glue only to a 1" x 1" area at the end of one strip per pair. I let the glue dry for 24 hours and pulled the strips apart. You can see the results in the photo: the HHG broke along the glue line, while the LMI glue and Titebond proved stronger that the surrounding wood. I'll be using the LMI glue for bridges from now on.

58575

Dan Uke
09-10-2013, 07:13 PM
Isn't the bridge made so the glue gives under too much stress or heat?

Liam Ryan
09-10-2013, 09:21 PM
Finally, someone has scientifically proven which glue is best.......

Moore Bettah Ukuleles
09-10-2013, 09:32 PM
From the photo it looks like Titebond held best. I've had miserable results with the LMI glue.
Most HHG failures are due to inexperienced users. You have to learn to use it properly before you can trust it and its not as easy as glue in a bottle. Too much fuss for me as I have never had any problems with Titebond Original.

It may indeed serve a function for a bridge to fail before destroying a top but not under normal circumstances.

Timbuck
09-10-2013, 10:25 PM
From the photo it looks like Titebond held best. I've had miserable results with the LMI glue.
Most HHG failures are due to inexperienced users. You have to learn to use it properly before you can trust it and its not as easy as glue in a bottle. Too much fuss for me as I have never had any problems with Titebond Original.

It may indeed serve a function for a bridge to fail before destroying a top but not under normal circumstances.

I've just had my first failure with Titebond original...A back to sides joint seperation on a soprano after almost one year....But I don't know the history of the uke, apart from it was first sent to an address in Canada in October 2012...and in August 2013 the seperation happened in Malta...Big climate difference I suppose :)...I'll still keep on using Titebond tho'

David Newton
09-11-2013, 03:46 AM
Finally, a thread about glue!
I bet I can do that same test and show that HHG is the best...

mzuch
09-11-2013, 04:50 AM
I bet I can do that same test and show that HHG is the best..

You're on!

Chris_H
09-11-2013, 04:55 AM
Finally, someone has scientifically proven which glue is best.......



I'm kinda slow sometimes, but... this is an example of humor... right? ;

Beau Hannam Ukuleles
09-11-2013, 05:05 AM
I'm kinda slow sometimes, but... this is an example of humor... right? ;

Chris, liam is showing a fine example of an ozzy taking the piss, as we say down under, and across and up (or down and around) in the UK.

Im with Chuck, the titebond looks like it held on the most and only let go when all else failed. All glue has to be is stronger then the wood it touches.

ps- i miss Rick

PhilUSAFRet
09-11-2013, 05:26 AM
Thank you very much for taking the time to do this and share it with us.

Moore Bettah Ukuleles
09-11-2013, 06:09 AM
Finally, a thread about glue!
I bet I can do that same test and show that HHG is the best...

Do it then. Find out for yourself as many of us have.

Liam Ryan
09-11-2013, 09:47 AM
Chris, liam is showing a fine example of an ozzy taking the piss, as we say down under, and across and up (or down and around) in the UK.

Im with Chuck, the titebond looks like it held on the most and only let go when all else failed. All glue has to be is stronger then the wood it touches.

ps- i miss Rick

The issue is more that this test, as unscientific as it is, in no way simulates the way the stresses work in a uke and nor does it consider the multitudes of reasons why a particular glue is used. Short term strength is not very high on the list of importance for my glue choices.

Chris_H
09-11-2013, 10:25 AM
my response was some good 'ol dry humor.. sorry.. I was appreciating your dry witted humor Liam! Sometimes I guess I am the only one that gets my humor... Yes, the first thought that came to my mind before I even finished the opening post was that the test proved absolutely nothing except that those boards, even though they were glued, they all three broke with stress.

I am NOT taking sides on any glues

lauburu
09-11-2013, 10:51 AM
Could we ask what force was required to break the respective joints? and how the force was applied? measured?
Miguel

mzuch
09-11-2013, 11:00 AM
the test proved absolutely nothing except that those boards, even though they were glued, they all three broke with stress.

No, two of the three boards broke. The HHG board did not break, the glue joint failed.

This was not intended to be a scientific study. Rather, it was my own inquiry as to whether I was using the best glue for attaching bridges. Could my batch of HHG be deficient in some way? Sure. Might the glue joints behave differently under different types of stress or with longer drying times? Possibly. Did I somehow apply the HHG wrong? I doubt it.

The point is: I have lost confidence in HHG for this specific use, so I'm making a change. YMMV. I intend to continue using HHG for joining plates, stacking heels and other functions that leave a visible glue line, but not for attaching bridges. I look forward to seeing the results of similar tests, scientific or otherwise, from other builders who may be willing to share.

mzuch
09-11-2013, 11:07 AM
Could we ask what force was required to break the respective joints? and how the force was applied? measured?

I made no attempt to measure the amount of force required to separate the pieces in each of the three glue-ups. I was trying to answer a more binary question: given sufficient force to separate the boards by pulling them apart with my fingers at the unglued end, would the break happen at the glue joint or would the glue joint prove stronger than the surrounding wood. I believe I got, for me, a satisfactory answer to that either/or question. Again, YMMV.

Timbuck
09-11-2013, 09:56 PM
"Destructive testing" it's called.....Now! glue three more test pieces together and wait 25 years before you break them apart ;)..Time and bio-degrading is the one test that we can't do very well. ....Or you can put them in the fridge or oven and test at differing temperaturs.:)

Allen
09-11-2013, 11:03 PM
If your point was to find which glue was best for bridges, then the test did tell you which. The one that snapped apart cleanly in my book is the one that I want to use. So it was HHG in the test that showed you that.

The PVA glues will cold creep to varying degrees. Will melt and harden again in a different position when subjected to a bit of heat. Might pull up slightly, etc. With HHG the joint in almost all the cases I've seen is either good, or fails. And if it fails with a nice clean separation, it's also dead easy to reattach.

As Rick Turner is so fond of saying. You need to do a lot of repairs to see what it is that fails in order to refine how you build, and why you choose to do things the way you do in your own building.

Titchtheclown
09-12-2013, 04:14 AM
I see a lot of glue tests in boatbuilding sites and believe it or not they boil glued up samples to accelerate decomposition.
The strongest glues fwiw are the resorcinol formaldehyde glues and some epoxys are the only ones rated for use in structural applications. However in low humidity environments pvas are as good. However to achieve the maximum strength from them you need tight fits and high clamping pressures. Almost no-one clamps pvas as tight as they need to for maximum strength. The other disadvantage they have is that they are wood glues, not glue glues so after curing they can not be re-glued at anywhere near the strength of a wood to wood clean bond.
The other thing is that most glues stick better to cleanly cut wood and sanding surfaces, rather than providing a key, clogs the microscopic pores of the wood and leaves torn loose ended fibres, resulting in a poor bond. Scraping and planing and machining provide better bonding surfaces.
Hide and other older glues may not be as strong but they are releasable and re-gluing provides a bond almost as strong as the original.

I hate foamy polyurethane glues. They are well over hyped.

Red Cliff
09-12-2013, 05:12 AM
I can't say I have done any tests - but there is a great chapter in a book called The Bowyers Bible where one of the authors (Tim Baker I think) conducted a 'scientific' break strength test on different glues. The force that glues go through in recurve and asiatic compound bows are many times greater than on musical instruments, and so such discussions are frequent on bowyers forums. I will try and upload the findings when I get home - but from memory the strongest glue by far (with the exception of Epoxy) was 'hide glue' made with Knox Gelatin - the stuff you buy in the baking section of a supermarket - which is just highly refined hide glue granules.

mzuch
09-12-2013, 06:45 AM
but from memory the strongest glue by far (with the exception of Epoxy) was 'hide glue' made with Knox Gelatin - the stuff you buy in the baking section of a supermarket

Thanks for this, Red Cliff. If the documentation confirms your memory, this result is surprising to me. I look forward to seeing what you find.

Liam Ryan
09-12-2013, 09:49 AM
Are we trying to work out which glue is best for bridges or which glue is strongest?

Chuck Dubman
09-12-2013, 06:45 PM
For a bridge, I'd worry about glue creep under string tension (probably more of an issue with steel strings than nylon). HHG cures crystal hard, won't budge. Yellow aliphatic and white PVA cure flexible, which is advantageous for carpentry, not so much for musical instruments.

How difficult are white and yellow glue to repair or reglue? That nice, clean break with your hide glue test piece only needs a shot of fresh hide glue to fix good as new. White or yellow glue will require scraping back to the wood, enough that you're not applying fresh glue over cured, which produces a weak joint.

Chuck Dubman
09-12-2013, 06:51 PM
My test blocks glued with Frank Ford's label glue recipe -- 1 package Knox gelatin to 1/3 cup of water, mix, microwave until 150 F -- couldn't be disassembled with a sledge hammer after drying overnight. The only comparable glue I've seen is polyurethane.

Liam Ryan
09-12-2013, 07:50 PM
How difficult are white and yellow glue to repair or reglue? That nice, clean break with your hide glue test piece only needs a shot of fresh hide glue to fix good as new. White or yellow glue will require scraping back to the wood, enough that you're not applying fresh glue over cured, which produces a weak joint.

In the case of those shown in the OP the broken splinters would have to be tediously removed and glue back in their rightful spots and then all the glue removed and then the two surfaces reglued. New glue won't stick to old glue properly.

If it was simply a matter of finding the strongest glue (which the OP's test certainly do not indicate) it would all be simple and easy.

Moore Bettah Ukuleles
09-12-2013, 09:09 PM
In the case of those shown in the OP the broken splinters would have to be tediously removed and glue back in their rightful spots and then all the glue removed and then the two surfaces reglued. New glue won't stick to old glue properly.

If it was simply a matter of finding the strongest glue (which the OP's test certainly do not indicate) it would all be simple and easy.

A joint that doesn't fail will never need to be reglued anyway so that point is moot.

Titchtheclown
09-12-2013, 09:30 PM
This test covers most glues used in boat building so it does not cover hide glues. Gives some tips on surface prep and clamping which can dramatically affect bond strength.
http://www.duckworksmagazine.com/08/columns/welsford/index5.htm

Building with modern glues should mean your uke should fall apart before the glue does at which point you should be asking yourself why you are treating your uke so bad.

Timbuck
09-12-2013, 11:46 PM
This test covers most glues used in boat building so it does not cover hide glues. Gives some tips on surface prep and clamping which can dramatically affect bond strength.
http://www.duckworksmagazine.com/08/columns/welsford/index5.htm

Building with modern glues should mean your uke should fall apart before the glue does at which point you should be asking yourself why you are treating your uke so bad.
I enjoyed reading that Titch..Some of the glue types I was unfamiliar with..Is the "Resorcinol" type glue any good for uke building?

Titchtheclown
09-13-2013, 03:42 AM
Resorcinol is what is used for structural applications like laminated veneer beams used to build houses and external/structural and marine grades of plywood. I have never used it myself but I think the black glue line and the fact that it stains everything might put the odd person off. Would make a strong uke but.

Tarhead
09-13-2013, 04:41 AM
If you're trying to compare bridge to top adhesion you really need to use the wood used in your bridge and the top. A softwood to softwood joint is a whole different animal vs Rosewood/Ebony/etc typically used for bridges to softwood tops. Off the top of my head here are some reasons for "Glue" failure:

Poor fit. Most glues don't fill gaps very well and are brittle by themselves.
Poor Preparation. Best glue joints are freshly machined/scraped hardwood surfaces to softwood. An old oxidized surface doesn't glue as well as a fresh one. A surface where the oils have been liberated with a solvent (ie: wiping the surface with Acetone, Alcohol, etc) is not as strong as a freshly milled one...especially with Epoxy.
Solvents used for clean up Solvents (Acetone, Alcohol) can be absorbed by the wood and weaken the bond.
Dry joint. Too much clamp pressure has been used (to correct a poor fit) or not enough glue used resulting in a weak joint.
Bad Glue Old glue, poorly mixed, overheated, worn out, frozen and thawed, etc

So...It's complicated.

Chuck Dubman
09-13-2013, 06:49 PM
In the case of those shown in the OP the broken splinters would have to be tediously removed and glue back in their rightful spots and then all the glue removed and then the two surfaces reglued. New glue won't stick to old glue properly.

If it was simply a matter of finding the strongest glue (which the OP's test certainly do not indicate) it would all be simple and easy.

If strength really matters, use a guitar type bridge with pins and a bridge plate.

David Newton
09-14-2013, 04:54 AM
So here is my test.
2 identical strips of Mahogany from the same piece, 2 identical "bridges" from the same piece, same for the lever.
Yellow glue, Hot hide glue. Same prep, sanding both surfaces to clean off any oxidized wood. Wipe both surfaces with glue, clamp for 24 hours, do the test 24 hours after that.
You can see the test, clamped both ends of the "top" and levered the bridge over at the "saddle".

Both pieces broke the top wood before the glue gave way, but I declare the hide glue the winner because the sound of it breaking was much richer, with overtones that are associated with a good sounding uke.

Yellow glue:
http://davidnewtonguitars.squarespace.com/storage/post-images/yellow.jpg
http://davidnewtonguitars.squarespace.com/storage/post-images/yellow%20broke.jpg

Hide glue:
http://davidnewtonguitars.squarespace.com/storage/post-images/hide.jpg
http://davidnewtonguitars.squarespace.com/storage/post-images/hide%20broke.jpg

Chuck Dubman
09-14-2013, 06:32 AM
Which removes strength as a variable from the equation. Both are well up to the task. For your next test, see which one takes stain without leaving a thin, yellow glue line.

BlackBearUkes
09-14-2013, 02:41 PM
Which removes strength as a variable from the equation. Both are well up to the task. For your next test, see which one takes stain without leaving a thin, yellow glue line.

I made hundreds of instruments using Titebond and I have never noticed a stain or color problem, or a seam problem of any kind. And as for the Titebond cold creep you mentioned, I have yet to have a guitar come into my shop in the past 20 years, Martins, Gibsons, etc,., that has suffered from this mythological problem. Seems like every time the subject of glue and Titebond comes up, someone is always quoting something they heard or read from someone else to bolster their believes. Yes, ALL glues will suffer when they are put to extremes in temperature, and in my experience, hide glues are the worst. I use hot hide glue all the time for the violin family of instruments, I don't use it for guitar bridges.

Beau Hannam Ukuleles
09-14-2013, 03:55 PM
.........................
58723

Chuck Dubman
09-14-2013, 08:27 PM
I made hundreds of instruments using Titebond and I have never noticed a stain or color problem, or a seam problem of any kind. And as for the Titebond cold creep you mentioned, I have yet to have a guitar come into my shop in the past 20 years, Martins, Gibsons, etc,., that has suffered from this mythological problem. Seems like every time the subject of glue and Titebond comes up, someone is always quoting something they heard or read from someone else to bolster their believes. Yes, ALL glues will suffer when they are put to extremes in temperature, and in my experience, hide glues are the worst. I use hot hide glue all the time for the violin family of instruments, I don't use it for guitar bridges.

Hard to argue with experience. On those rock-steady guitar bridges, were the strings tied on, or pinned through the top and into a bridge plate?

Michael N.
09-15-2013, 10:27 AM
I think you will find that HHG gives better results if you size the joint first. Most HHG failures are due to user error - too cold, too thick or too thin - resulting in a weakened joint.
I've posted this a number of times and it doesn't seem to get much notice. If you really want to find out the strength of HHG look at Baroque Lute bridges. 22 strings each pulling around 3 Kg's = 66 Kg's total. All on a bridge that is not much more than 12 mm's wide! There's simply no comparison with the tension found on a Ukulele. Even a modern Classical Guitar doesn't reach that type of tension. The only comparison one can make is with a Steel String Guitar and that bridge is MUCH wider than a Lute bridge. They aren't pinned bridges either, the strings pull directly on the bridge itself.

Michael N.
09-15-2013, 10:33 AM
I made hundreds of instruments using Titebond and I have never noticed a stain or color problem, or a seam problem of any kind. And as for the Titebond cold creep you mentioned, I have yet to have a guitar come into my shop in the past 20 years, Martins, Gibsons, etc,., that has suffered from this mythological problem. Seems like every time the subject of glue and Titebond comes up, someone is always quoting something they heard or read from someone else to bolster their believes. Yes, ALL glues will suffer when they are put to extremes in temperature, and in my experience, hide glues are the worst. I use hot hide glue all the time for the violin family of instruments, I don't use it for guitar bridges.


Sorry but you are wrong. For HHG to give way you need both heat and moisture. Heat alone has little effect although high heat may make it brittle. I've done many fretboard removals glued with Fish, HHG, PVA and Epoxy. The most difficult to remove (with heat alone) is Fish Glue followed by HHG. Epoxy and PVA are easier but you are then left with cleaning up the goo.
Go to Frank Fords website. He's done the oven test on a couple of glues, including HHG.

http://www.frets.com/FretsPages/Luthier/Data/Materials/GlueTest/gluetest.html

lauburu
09-15-2013, 11:05 AM
Is the "Resorcinol" type glue any good for uke building?
I have used resorcinol in furniture building and it sets like rock. Have also used it in laminated ukulele necks. If used next to a dark wood, the dark glue line is less of an issue.
Miguel

BlackBearUkes
09-15-2013, 12:24 PM
Both type of bridges, steel string and classical.

BlackBearUkes
09-15-2013, 12:42 PM
Sorry but you are wrong. For HHG to give way you need both heat and moisture. Heat alone has little effect although high heat may make it brittle. I've done many fretboard removals glued with Fish, HHG, PVA and Epoxy. The most difficult to remove (with heat alone) is Fish Glue followed by HHG. Epoxy and PVA are easier but you are then left with cleaning up the goo.
Go to Frank Fords website. He's done the oven test on a couple of glues, including HHG.

http://www.frets.com/FretsPages/Luthier/Data/Materials/GlueTest/gluetest.html


How much moisture is in a closed up car in the heat of summer where the temp gets to 150 degrees for an hour? Obviously just enough. I've had guitars and violins come into my shop that have been baked, and they were not together and in one piece. Quoting tests someone has done doesn't always simulate real life. I tend to work from my experiences, not Franks or anybody else. I have also removed many fingerboards from instruments and most of the time, even dry heat does the job. Your experience may be different.

Michael N.
09-15-2013, 12:50 PM
You mean in that scenario PVA glues are fine but HHG isn't? That is contrary to ALL of my own experience and if the test is anything to go by (I think it is) that would mean the Titebond would give way long before the HHG.
I'll give you another example. One I've done hundreds of time. Glued up Binding and purfling with HHG and then bent them on a hand bending iron. As you know bending irons get seriously hot but the pieces don't delaminate. I've done the same with PVA and the glue gives in. That again proves that HHG can take more heat than PVA.

BlackBearUkes
09-15-2013, 01:01 PM
You mean in that scenario PVA glues are fine but HHG isn't? That is contrary to ALL of my own experience and if the test is anything to go by (I think it is) that would mean the Titebond would give way long before the HHG.

I never said that. I said the guitars and violins came apart and I have said many times that NO glue does well when it comes to extremes in heat or cold for extended periods of time. Its just glue and all glues have weaknesses.

I had a middle range classical guitar come into my shop about 3 weeks ago. The kid who brought it in said he had the bridge glued back on twice in the last month, and the last time the guy (luthier) told him that would be the last time he would have that problem because he used HHG for the repair. One week later the bridge came off again. The kid said he wanted me to repair it but did not want HHG used. I used Titebond and everything seems to be fine. Probably just lucky on my part.

Michael N.
09-15-2013, 01:14 PM
No you stated that HHG is more susceptible to heat. It isn't. It's less susceptible to heat than PVA/Titebond. That's not a question of opinion, it's scientific fact. It's also why you can use PVA glues in iron on veneering - the heat triggers the thermo plastic nature of the glue. You simply can't do that with Hide glue without introducing moisture as well.
TBH I think the kid needs to find someone who knows how to glue a bridge on with HHG. Every single one of my bridges is glued with HHG and not one has been glued with the aid of a clamp. I don't even do a rubbed joint. Just light finger pressure for around 4 minutes. Amazing!!
And still no one takes note of my point on the Lute bridge!!! It's there in front of everyone. For all to see. I don't know of one single Lute maker who uses Titebond or any other modern glue for their bridge. Maybe, just maybe they know how to use HHG.

BlackBearUkes
09-15-2013, 01:36 PM
No you stated that HHG is more susceptible to heat. It isn't. It's less susceptible to heat than PVA/Titebond. That's not a question of opinion, it's scientific fact. It's also why you can use PVA glues in iron on veneering - the heat triggers the thermo plastic nature of the glue. You simply can't do that with Hide glue without introducing moisture as well.
TBH I think the kid needs to find someone who knows how to glue a bridge on with HHG. Every single one of my bridges is glued with HHG and not one has been glued with the aid of a clamp. I don't even do a rubbed joint. Just light finger pressure for around 4 minutes. Amazing!!
And still no one takes note of my point on the Lute bridge!!! It's there in front of everyone. For all to see. I don't know of one single Lute maker who uses Titebond or any other modern glue for their bridge. Maybe, just maybe they know how to use HHG.

I have always found it much easier to remove a bridge or fingerbaord that is glued with HHG then with a PVA. I have had a shop wall full of old guitars that used HHG and practically every one of them came in with no bridge, loose braces, loose neck joints and the binding loose or missing. It seems to me, that working with old instruments the thing I noticed most over a 20 year period, it that HHG gets weaker with time. I realize that much of this is due to the mistreatment or abuse the instrument has suffered. I also realize that that is the only glue they used most of the time. I like HHG and use it on a regular basis when it is called for, like restoring a vintage guitar or violin. I don't use it on most of my own instruments except violins and some classical guitars.

As for lute makers, whatever works for them, fine.

Michael N.
09-15-2013, 02:05 PM
Well no one knows how badly those instruments were glued in the first place. Not only that but Hide glue is a variable product - both in it's production and in it's use.
15 years ago I worked in a Violin repair shop. It actually belonged to a friend and I did very little repairs to Violins but I did get the Guitar work. I was their 4 years. Of all the old Schobach/mittenwald Fiddles I can only ever recall one where the centre seam needed regluing. Some of those instruments are near 200 years old. I own one from 1912. Centre seams are perfectly intact and have never been touched. Hide glue does not deteriorate with age. If it did it would have been well documented by now. It hasn't. All those restorers who work on Amatis, Strads etc. would have noticed weakness in the original 350 year old glue. . . but they haven't.

Chuck Dubman
09-16-2013, 04:20 PM
Sorry but you are wrong. For HHG to give way you need both heat and moisture. Heat alone has little effect although high heat may make it brittle. I've done many fretboard removals glued with Fish, HHG, PVA and Epoxy. The most difficult to remove (with heat alone) is Fish Glue followed by HHG. Epoxy and PVA are easier but you are then left with cleaning up the goo.
Go to Frank Fords website. He's done the oven test on a couple of glues, including HHG.

http://www.frets.com/FretsPages/Luthier/Data/Materials/GlueTest/gluetest.html

How hot did King Tut's tomb get? That would be the ultimate test, like leaving your uke in a car for 3,000 years. Any wooden artifacts would have been assembled with hide glue. How many pieces came out intact? How many came out in splinters?

tobinsuke
09-18-2013, 04:55 PM
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58723

I haven't been following this thread closely, figuring I'd just check back every now and then so I missed this for a while... Beau, eloquently posted. If you can't believe Honest Abe, then I don't know what the world is coming to. Brilliant.