Which Wood Glue?

[Greg Nelson]

I do connect the Gorilla brand name with the original poly glue they offer. I see the name and it's like "Kleenex" instead of "Facial tissue". I wasn't even aware they had expanded into a standard PVA but my local hardware store is carrying the CA version.

I also like old fashioned Elmer's white glue for some things. Bonds well and dries clear. Just because they give it to pre-school kids because it's non toxic doesn't mean it doesn't bond well.

Greg N

[Itzkinguitars]

Completely unrelated, but I've only seen you post on the luthier forum Greg. Branching out?

[Greg Nelson]

I have posted here on rare occasions but I do try and limit how many places I post. I would rather be cutting wood than typing and forum life can really be time consuming.

Greg N

[cadam5150]

Originally Posted by cadam5150

Thanks for your advice. I will try the Gorilla for some applications.

I have tried the Gorilla Wood glue. When dried, it leave almost no immediate visible trace. Indeed, it sets pretty fast. The next step is strength testing.

[arie]

Originally Posted by cadam5150

I have tried the Gorilla Wood glue. When dried, it leave almost no immediate visible trace. Indeed, it sets pretty fast. The next step is strength testing.

Not a scientific study in any way shape or form, but I bought some Gorilla Wood Glue last friday to try out. I glued two pieces of mahogany together, applied a clamp and didn't wipe off my usual minimal squeeze out. It sets up very fast and when dry is appears clear but leaves a wet look to the areas that aren't wiped up before it dries. Looking under a 10x loupe shows tiny bubbles in the glue maybe a couple of thou. in diameter and evenly distributed. When cleaning up squeeze out about 24 hours later with a chisel, the glue was very tough and somewhat gummy and tore with a uncured epoxy like texture.

On the reverse side of my sample I repeated with Titebond Original Wood Glue. Pretty much the same conditions. About 24 hours later I cleaned up with a chisel and looking under the 10x loupe didn't reveal any bubbles. The Titebond seemed to have more shrink (compared to GWG's nearly none) and the glue seemed harder and chipped away with a crystal like shattering rather then tearing away as with the Gorilla Wood Glue.

Obviously not enough data to come to a conclusive answer (and honestly I don't want glue study to be my life's work) but I suspect that GWG may offer more toughness then hardness. I'll probably experiment with it at a later date some more.

[cadam5150]

Originally Posted by arie

Not a scientific study in any way shape or form, but I bought some Gorilla Wood Glue last friday to try out. I glued two pieces of mahogany together, applied a clamp and didn't wipe off my usual minimal squeeze out. It sets up very fast and when dry is appears clear but leaves a wet look to the areas that aren't wiped up before it dries. Looking under a 10x loupe shows tiny bubbles in the glue maybe a couple of thou. in diameter and evenly distributed. When cleaning up squeeze out about 24 hours later with a chisel, the glue was very tough and somewhat gummy and tore with a uncured epoxy like texture.

On the reverse side of my sample I repeated with Titebond Original Wood Glue. Pretty much the same conditions. About 24 hours later I cleaned up with a chisel and looking under the 10x loupe didn't reveal any bubbles. The Titebond seemed to have more shrink (compared to GWG's nearly none) and the glue seemed harder and chipped away with a crystal like shattering rather then tearing away as with the Gorilla Wood Glue.

Obviously not enough data to come to a conclusive answer (and honestly I don't want glue study to be my life's work) but I suspect that GWG may offer more toughness then hardness. I'll probably experiment with it at a later date some more.

Thanks for sharing your findings. I am thinking of conducting a home-made shear test to see if the Gorilla is really a Gorilla. Do share you future findings.

I have a gut feel that these synthetic wood glues are not drastically different from one another because they are meant to stick pieces of wood together. Well, it is widely discussed among experienced luthier regarding the "preferred choice(s)" that comes with all the pros and cons. If there are options available in the market, I guess it is no harm in trying them.

I suspect when synthetic wood glue was initially introduced, the purists may have their conservative views over such man-made stuffs as substitute for the organic stuffs. Over time, certain synthetic wood glues were accepted and some are elevated to cult status and appear to be un-replaceable. In the spirit of curiosity and discovery, I believe there are other synthetic wood glues that can satisfy the stringent requirements of guitar makers too.

The only way to know is ... give it a shot.

[theEdwinson]

For most applications, I prefer to use the LMI white Instrument Maker's Glue. It's fast setting, extremely strong, dries very hard (and clear) and if you believe the hype, it doesn't "creep" the way Titebond sometimes can, if your guitar is exposed to non-catastrophic heat, like being left on a stand in your living room, in direct sunlight.

For oily/ resinous woods, like Cocobolo and other rosewoods, always wipe down your gluing surfaces with acetone before gluing and clamping.

Be careful not to "starve" your glue joint by applying too much clamping pressure.
I find that it's a good idea to increase your clamping pressure gradually, to get full contact between gluing surfaces, and allow the glue to sink into the wood.

Personally, I will not use the Gorilla Wood Glue for anything but light duty. I bought a bottle a few months ago, and tested it with the LMI white glue and Titebond Original formula. Not a scientifically controlled test, but yielded good information--I glued two pieces of maple together crosswise for each glue, like a "plus" sign, with light clamping pressure. When they were well set, I clamped the pieces into my bench vise and bashed them with a hammer. The Gorilla wood glue broke in the glue joint with very little force. The Titebond one took a good strong whack, and left a lot of wood fibers behind on the opposite side glue joint. The LMI glue held so well, the wood broke, leaving the glue joint intact.

[zabdart]

My thanks to Greg for a very informative post.

[Bruce Sexauer]

Sounds like the polyurethane glue, Edwinson, which breaks exactly like you describe. I'd be surprised to hear you are talking about the glue Laurent uses. Not that I've used it, but I pretty much trust Laurent to use the right stuff.

[Laurent Brondel]

Thank you Bruce.

IME Gorilla wood glue is as strong as TB1 in shear tests, and has better heat resistance: it lets go at higher temps, which for me means less possible creep when exposed to heat. Not that it matters, because for all joints that could creep I personally use HHG.
Gorilla wood glue sets much faster than TB1 though, I think I mentioned it.
The strength of a glue can not be measured by the hardness of the exposed cured or half cured glue, this is a myth: what matters is the solidity of the chemical bond with the wood. In any case when totally dry Gorilla wood glue squeeze out is pretty hard.
Edwinson, IME a joint is never starved because of excessive pressure, but because of not enough glue in the joint, especially if there is end grain and it hasn't been sized. Again, it is a chemical bond.
The only glue I know of that has integral strength (and because of that, excellent gap filling properties) is good epoxy.

[cadam5150]

Originally Posted by Cminor7sus4

For most applications, I prefer to use the LMI white Instrument Maker's Glue. It's fast setting, extremely strong, dries very hard (and clear) and if you believe the hype, it doesn't "creep" the way Titebond sometimes can, if your guitar is exposed to non-catastrophic heat, like being left on a stand in your living room, in direct sunlight.

For oily/ resinous woods, like Cocobolo and other rosewoods, always wipe down your gluing surfaces with acetone before gluing and clamping.

Be careful not to "starve" your glue joint by applying too much clamping pressure.
I find that it's a good idea to increase your clamping pressure gradually, to get full contact between gluing surfaces, and allow the glue to sink into the wood.

Personally, I will not use the Gorilla Wood Glue for anything but light duty. I bought a bottle a few months ago, and tested it with the LMI white glue and Titebond Original formula. Not a scientifically controlled test, but yielded good information--I glued two pieces of maple together crosswise for each glue, like a "plus" sign, with light clamping pressure. When they were well set, I clamped the pieces into my bench vise and bashed them with a hammer. The Gorilla wood glue broke in the glue joint with very little force. The Titebond one took a good strong whack, and left a lot of wood fibers behind on the opposite side glue joint. The LMI glue held so well, the wood broke, leaving the glue joint intact.

Appreciate your sharing. I have noted that the failure mechanics in this test is of shock load's nature. In most normal settings, the joints on any given guitar is subject to creeping stress which is very different in nature. With the application of shock loads, the wood on a given guitar may very well give way. Even if the glue joints hold, the guitar is still damaged. In this case, the strength of the glue is irrelevant.

Currently, I have re-glued the bridge of an old 12th-string guitar using the Gorilla wood glue. I will be able to monitor the duration of the bridge and share the findings when appropriate.