Glue strength -- actual numbers?

[Carlos Moreno]

Hi,

I'm wondering if someone knows the actual numbers on glue strength? (i.e., strength per unit of surface)

I'm talking about the plastic glue (yellow or white -- I think it's vynil-based), assuming that it is used to glue two pieces of very-flat very-clean along-the-grain wood surfaces, with no gap between the surfaces of more than

1/200" or so. At least typical values, or worst-case values (if it depends on the wood, or on the angle of the surface with respect to the grain, etc.)

A google search on this newsgroup returns nothing; the specs of the glue (both on its label and on Lepage's web site) only include the catchy advertising phrase "bonds with 2 tons of strength" (GOD, such idiots!! Only for that I shouldn't buy anything from them!!! :-( such flashbacks of infomertials advertising crap), so I'm at a loss.

Anyway, I'll be grateful for any info!

Thanks,

Carlos

--

[David]

Check out

They have the PSI ratings for their glues.

David

Carlos Moreno wrote:

[Brian Morris]

this site they own Tite bond adhiesive.

[Brian Morris]

site they own tite bond adhiesives

[Sbtypesetter]

The LMI catalog had a short note on glue strength a few years back. I cwn't even begin to recall the numbers but I can say this much.

• Shelf life will improve if kept in the refrigerator.

• Shelf life is much shorter than you might suspect.

• LMI offers a yellow glue with about double the strength of off-the-shelf yellow glue. The price is much higher and when kept cool the shelf life is only about six months.

• Yellow glue is non gap filling. The strength comes from infusing the pores of the wood. Therefore the wood needs a smooth finish but not burnished as this will inhibit absorption.

• You are correct on a gap of 1/200th inch.

• Clamping pressures are much lower than most every woodworker uses. Too much pressure will result in a starved joint.

• A perfect joint is much more important than one mught suspect. Never clamp tight to close a joint. Some sections of the joint will be starved, other just right, and other gap filled. Take the time to get the joint right.

*Regular yellow glue (A.R.G.?) is usually stronger than the wood being joined.

That about exhausts my knowledge. Hope I was of some help.

-Rick Buchanan

[George]

Enough to know that the glue adheres to itself with greater strength than the wood has along the grain. Unless, of course you don't spread or clamp properly. The rest is hype for woodworkers, because the material is too variable for precise data to be meaningful.

[Guess who]

Why do you need to know? Have you had glue failure? What are your spec requirements that the manufacturer should meet? Most modern brand-name glues do far more than necessary to hold two pieces of wood together, so the actual rating is unimportant unless you are using it to build a 747, in which case you'd better make sure as well that the cuts are flat-accurate to =/-.001" or better. For any glues I know the wood would shatter well before the bond broke. Any break I've seen has had wood stuck to it, showing that the break was in the wood, and not between glue and wood [actual surface-surface bonding]. I'd be more concerned with other problems such as how long does it take to set. I had one that grew a mould [mold, US] and had to dump most of it.

[Carlos Moreno]

Thanks to all that replied.

Yes, I guess this is the bottom line -- and I did know it; it was partly curiosity to know the numbers. I remember our teacher (in an introductory woodworking course I took) mentioned the actual number, and he did a demonstration; he glued together a couple of pieces by their edges, and then fixed it, took a hammer, and invited us to try and break it -- naturally, the piece kept breaking anywhere except at the glued surface!

Thanks,

Carlos

--

[Leon]

True but,

The jury is still out on this one as it has not been prooven either way. Apparently many people that clamp too hard are trying to close a gap and as indicated, yellow glues do not fill gaps well. I have never had a joint fail whether I clamped agressively or not. I choose moderate clamping pressure now.

[Larry Jaques]

On Wed, 03 Nov 2004 23:45:51 -0500, Carlos Moreno calmly ranted:

What more do you need to know (about strength) than the fact that the glue is stronger than the wood it bonds?

Don't heat the joint to 150F+ (or soak it in vinegar) and the bond will last your lifetime or longer.

-------------------------------------------------------- Murphy was an Optimist ----------------------------

Comprehensive Website Development

[J T]

Wed, Nov 3, 2004, 11:45pm moreno_at_mochima_dot [e-mail] (Carlos=A0Moreno) mumbled: Hi, I'm wondering if someone knows the actual numbers on glue strength? (i.e., strength per unit of surface)

In any practical applications, it doesn't matter, they're all stronger than the wood.

JOAT When you choose an action, you choose the consequences.

- Unknown

[David]

Not so sure I agree with the "starved joint" syndrome, merely from the application of "too much" clamping pressure. Damaged wood fibers can result from behemoth pressures, but more likely a "starved" joint is due to insufficient glue applied BEFORE clamping the joint, as opposed to the pressure of the clamping being the culprit.

David

Sbtypesetter wrote:

[Never Enough Money]

I couldn't find the strength data ... but I sure do like Gorilla glue. It's strong but has other desireable properties. It's waterproof, it's sandable, and glues a lot more than wood, etc.

[bridger]

overclamping can starve the joint.

[Sbtypesetter]

Did manage to get a starved joint in my younger years. Wanted a "really strong joint" so I clamped it as tight as possible. Lots of squeeze out. It fell apart. The joint was dry. -Rick

[David]

Yeah, like going swimming within 1 hour of eating will cause drowning from cramps. You are repeating a myth.

David

[e-mail] wrote:

[George]

If you apply clamping pressure immediately and excessively, you will squeeze so much out that you can actually break on the glue line after cure, especially on woods like hard maple which don't soak much. It's NOT a myth to an Industrial Arts teacher who's seen what teenage males can do to pipe clamps....

[Lew Hodgett]

RE: Subject

1) Epoxy with micro-balloons 2) Resorcinol

After that, it's all down hill.

[David]

Talk to the folks at Franklin. Tell them they don't know their business.

David

David

George wrote:

[George]

Why bother? They're probably as closed-minded as you are. Mine's by experience, can't change that.