Glue test in Fine Woodworking magazine

[mikec]

Provided Link: Glue test article (http://www.taunton.com/finewoodworking/Materials/MaterialsArticle.aspx?id=28853)


And good ol' carpenter's yellow glue came out on top!

They made "bridle joints" -- take two pieces of wood about 2" wide and the same thickness (ususaly 3/4") and cut a slot centered in the end of one piece of wood the width of the other pieces and one third the thickness.

Then notch each face of the other stick one-third the thickness so that it slips into the slot on the first stick.

The made three versions (Tight-required force to get the pieces together, Snug -- fit together with hand pressure but not easily and Loose - a playing card could slip into the gap)

They tested Six types of glue (waterproof and standard PVA, liquid and hot hide, slow-set epoxy and polyurethane) on Maple, Oak and Ipe. (sorry, no MDF )

Total of 162 samples(!) were sent to a university engineering lab and busted. (carefully and precisely, of course)

Results were Waterproof PVA best at 2024 lbs avg, then epoxy (1994) PVA (1924) Liquid hide (1595) hot hide (1531) and polyurethane (1164)

Yep, they were surprised!

The poly was really poor in the "loose" joint -- only about one-third as strong as the best!

Gonna be some head scratching over that!

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[shawn_a]

And it's nice to know I've been right all along. I figured out long ago that if I could break the wood before the glue joint broke it was good enough bonding strength. Good ole' yellow goo, ya gotta love it.

shawn

[thylantyr]

Nobody said that yellow wood glue isn't good.

The other esoteric glues have their place
depending on the situation and material {non wood}.

Polyurethane glue and epoxy is really good stuff for certain applications, it can do stuff yellow
glue can never do.... but there is so many
formulations of epoxy that many aren't that good.

[Bruce]

This has already been discussed below.

FWIW, knowing the appropriate application for each type of glue is where one should start.

Yep, the PVA glues are excellent and cheap. They cure hard and inflexible. Any seep-out can mess up surfaces that need to be stained later.

Polyurethane does remain reflexible after curing - that's one of its qualities. For instance, it's used by book restorers to re-glue the bindings on old books because it will remain flexible for years. Poly also takes stain (perhaps because of its porous nature).

Winning a joint destruction test is not the only thing one should consideration when choosing a glue for building speakers.

It's really a matter of personal preference and comfort with using a particular glue.

[mikec]

The weakness of them all as "gap fillers" was a big surprise.

And the BIG difference between poly and PVA was a real shock.

But you are right about the "squeeze out" difference -- much easier to clean up poly when it's dried, etc.

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[gychang]

> The weakness of them all as "gap
> fillers" was a big surprise.

> And the BIG difference between poly and PVA
> was a real shock.

> But you are right about the "squeeze
> out" difference -- much easier to clean
> up poly when it's dried, etc.

I use tite-bond?, is this considered a poly? or PVA?

[mikec]

White is Type I, Waterproof is Type III



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