Official Luthiers Forum!

Gorilla has done nothing short of a fantastic job marketing their product. Polyurethanes, in my experience, are best suited to special applications. In terms of performance as wood glues they are not far from epoxies, and are exceptionally brittle. They are among the most prone to true adhesive failure, particularly when exposed to shock. CA was most likely excluded because the method in this article applied shear stress (parallel to the glueline.) For most adhesives, shear is the strongest direction and this is also true for wood. However, CA is very weak in shear and strongest in tension. In fact, it is commonly used for sheet metal operations where it is useful to tack a work piece in position quickly and then giving the edge a quick whack with a hammer to separate it. One point definitely worth noting for anyone doing spot repairs with CA is to never use activator spray if it can be avoided. Strength is decreased and the adhesive is more likely to become opaque due to stresses induced by the accelerated reaction. I have personally seen strength losses approaching 50% due to the use of activators.

ROFLOL...

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Don't know how I missed Todd's reply.

People are often shocked upon learning that HHG can go toe to toe with any modern PVA any day of the week. In terns of strength, thermal resistance, and exceptional lack of creep it is effectively a perfect wood glue. It is also fully reversible and requires no special preparation for reassembly. For musical instruments, complaining about its lack of water resistance is comical (when I say water I mean direct contact with water, high humidity isn't the same thing.) The only legitimate drawbacks are lengthy preparation time, and handling properties that can make its use difficult or impossible. I have some biochemical tricks up my sleeve that should theoretically prevent degradation of liquid hide glue. About a year and a half ago I succeeded in modifying soy flour to pass Type II water resistance. Would I love to develop enhanced biologically derived adhesives? Absolutely. But I have yet to find an adhesives company willing to deviate from traditional synthetic polymer chemistry... Not to mention I'm not going to give such concepts away.

I am, however, absolutely certain that non-toxic, structural, water-resistant biological adhesives can be produced with current technology. Perhaps some day we'll have our cake and eat it too.

Until then: Don't ever sell HHG short. It's amazing stuff.

Thanks Hugh for the informative replies.

The use of the brindle joint, without clamping, and then loading the joint in rotation is not a good way to test the shear load.
It would be very difficult to ensure you did not wipe out some glue when assembling.
It would have been better to have lapped two pieces onto a central one with appropriate clamping, and then loaded axially.