Wood Adhesives

[Dan O'Connor]

What is stronger for bonding pieces of wood: Epoxy or Wood Glue?

[Edwin Pawlowski]

A proper joint with either should hold better than the wood itself.

Other conditions may make a difference. Dampness, high temperature, etc. Epoxy can fill a gap. Ed

[Dan O'Connor]

[Edwin Pawlowski]

If the wood breaks before the joint breaks, it makes no difference. That is the case with good wood glue or epoxy.

In general, epoxy is a stronger adhesive than most wood glues, but unless you have certain other reasons to use one over the other, base your decision on ease of use. Ed

[Bay Area Dave]

If waterproofness is NOT an issue, then it doesn't matter. Wood glue properly applied is gonna be as strong as the wood, so what do you gain by spending more $$ for epoxy, plus cleanup is no fun.

dave

Dan O'C> What is stronger for bonding pieces of wood: Epoxy or Wood Glue? > >

[Dan O'Connor]

[Bay Area Dave]

yes?

dave

Dan O'C> Anyone??

[Charlie Spitzer]

it depends upon the specific glues, the wood type, the tightness of the wood interfaces, and a whole host of other dependencies. iow, we need more information.

[admin]

the answer is "Yes".

Or alternatively, "No"

Everything depends on: (1) the particular glue involved (2) The type(s) of wood, and/or other materials, involved (3) The type of joint (4) The quality of the fit

just for starters.

In general, with a precise fit between the pieces, _any_ quality glue,

*USED*PROPERLY*, will be _significantly_ stronger than the surrounding wood. "How much stronger" is essentially a moot point, since the wood next to the joint *will* fail before the joint itself fails.

There are some 'fundamental' considerations, like it's usually a Bad Idea(TM) to use a water-based glue on materials that will suffer adverse effects from exposure to water (e.g. MDF, cheap particle-board, etc.)

[Bay Area Dave]

I'm beginning to wonder if he bought a can of epoxy and wants confirmation it was worth the price! :)

dave

Charlie Spitzer wrote:

[Edgar Svendsen]

I don't disagree with anything you said. But joint strength has many dimensions; how long will the joint stay strong, how does the adhesive react to wood shrinkage over time, the dowels in many chairs are well fitted at the factory, still those doweled joints almost always fail after a while; which adhesive will minimize this effect? The glue joints in plywood seem to always fail near the edge if it shows; is this effect independent of the adhesive used? I think the issue is more complex then you implied.

Ed

[admin]

He didn't ask about joint strength. :)

Joint strength is a complex issue. with _what_ 'adhesive used' being a relatively -minor- consideration.

"uniformly badly" -- pretty much regardless of the type of glue used. :)

Again, *almost*always* it is _not_ the glue that fails. the wood fiber _itself_, NEXT TO where the glue is, gets torn.

Have you noticed any consistency in the type of glue used in the failures _you've_ seen?

"Interior" grade ply _is_ subject to ply separation in the presense of moisture. Airborne humidity can 'wick in' at an exposed cut edge, which structurally weakens the ply, so the wood 'tears' easier.

Note that this has -nothing- to do with the glue used for the _joint_ itself. :)

The 'mechanics' of joint failure *is* a complex issue, no doubt about that. The type of glue used is usually _not_ a significant factor. Other issues, primarily 'joint design', 'joint loading', 'fit', 'surface preparation', and 'proper application of the adhesive', among others, tend to dwarf it.

A _real_ 'hide glue' -- the variety you have to keep in a hot pot -- has an excellent combination of "stick-to-it-iveness", surface penetration, and flexibility. OTOH, it is a *bitch* to prepare and keep ready, requires con- siderable knowledge and 'care' in application, and has to be used in a timely manner. Virtually all modern adhesives are 'inferior' in one way or another, but (more than) make up for that inferiority in 'ease of use'.

[Larry Jaques]

On Wed, 15 Oct 2003 21:18:02 GMT, "Dan O'Connor" pixelated:

Either. Both are stronger than the wood they bond. If the project might get wet/stay moist, use epoxy and a good finish.

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[Simon]

Not totally true because some polyurethane and epoxy glues are developed with a large degree of flexibility

Not one mention of polyurethane glues or methylmethacrylate glues yet ... keep going everyone

:-)

And glue type does have a significant factor in joint failure where the wood fibres tear next to the joint, how far the glue penetrates in to those fibres is dependent on the viscosity of the glue. Moisture curing adhesives like gorilla glue will seek out the moisture in the wood and penetrate further, bonding with the moisture and reinforcing the surface fibres (don't get me started on the mechanics of surface fibres ;-).. ), thus making a stronger joint, generally speaking, but stronger than what? what are we comparing it to?.

as some have mentioned, there are literally many glues types with hundreds of variations of those glue types as well as different woods behaving in different ways and your question (The OP) was just a wee bit too general to give an answer to. ;-)