Woodworking Glues (WOOD Mag)

[Chris Padilla]

WOOD had an interesting centerfold in the newest issue about glues.

I am surprised to see that Polyurethane glues to actually be weaker than good old yellow glues. In fact, the new Titebound III is the strongest glue out there except for epoxies!

I was under the (misguided from marketing?) impression that poly glues were pretty strong. Poly has better resistance to heat but other than that, it isn't much better than the Titebound III other than it costs double!

I am glossing over some other points but basically I guess poly ain't all it is cracked up to be!

One interesting point I took away:

Moisture delays water-base glues; dry conditions delay polyurethane...from reaching full-strength.

[Dick Parr]

Thanks for sharing the info Chris. I don’t get Wood Magazine any more and that is some interesting information. I was going to pick up some poly this week for my next batch of pens that I just got from Ken, but now maybe I will try out the new Titebond III instead.

[Jim Becker]

Thanks for sharing the info Chris. I don’t get Wood Magazine any more and that is some interesting information. I was going to pick up some poly this week for my next batch of pens that I just got from Ken, but now maybe I will try out the new Titebond III instead.

TB III isn't going to be good for your pens...you are joining metal to wood. The poly is still appropriate for the job. You have to remember what the properties of a glue are. PVA (including "new" formulas like TB III) needs to get into the cell structure of the material it's joining to work properly. Choosing the right glue isn't just a matter of strength. Material to be joined counts, too.

[Dick Parr]

Thanks Jim your right, guess I was a little brain dead yesterday. Just got back from 4 days of camping and was a little tired. I do remember about the bonding of the cell structures, after you reminded me.

I will still get the poly for the pens as everyone has attested to it being about the best for that process. I have been using ca glue with no blow outs, but it sounds like I have been lucky so far.

Thanks again.

[Bob Marino]

Interesting pullout and info on the glues. Also in the magazine was a short q & a with a guy who uses only epoxy on his furniture.

Bob

[Mark Singer]

I was using the Polyurethane glues for a while and had several joint failures at which I stopped using them completely. I use West Systems and Tightbond 2 or Lee Valleys glue for eveything. The poly glues are very messy and short shelf life....why mess with them?

[Bob Marino]

Mark,

Any reason why you choose one glue over another for a particular application?

Bob

[Chris Padilla]

Let's see:

Yellow Glue has 2 year shelf life.
Yellow Extended has 1 year.
Dark Wood has 2 year.
Titebond II has 2 year.
Titebond II Extended has 2 year.
Molding and Trim has 1 year.
Titebond III has 1 year.
Polyurethane has 1 year.
Epoxies and CA have 1 year.

It is true that the poly/epoxy/CA do bond more materials than the yellows. Yellow can bond wood, leather, cloth, and paper. Poly/Epoxy/CA can bond most materials except some plastics.

This is a good issue (June/July 2004, Issue 156) to pick up at a stand somewhere. You can remove the guide and pin it up on your wall.

[Bill Grumbine]

I don't know about those shelf life figures. I have glue that is WAAYYY past its date that I still use regularly and it works just fine. For example, I still have a bottle of Elmer's polyurethane glue that has to be a minimum of six years old, and it still cures and holds like it did when it was new. I only use it for one small job and some occasional pens, but it works and works well. I also have a gallon bottle of Titebond Extend that is years old, but still holds. And as far as epoxy goes, everything I read when I was building my boat says that epoxy has a shelf life that is practically indefinite. Again, I am using epoxy from 1998 and it still works fine.

Bill

[Donnie Raines]

I don't know about those shelf life figures. I have glue that is WAAYYY past its date that I still use regularly and it works just fine. For example, I still have a bottle of Elmer's polyurethane glue that has to be a minimum of six years old, and it still cures and holds like it did when it was new. I only use it for one small job and some occasional pens, but it works and works well. I also have a gallon bottle of Titebond Extend that is years old, but still holds. And as far as epoxy goes, everything I read when I was building my boat says that epoxy has a shelf life that is practically indefinite. Again, I am using epoxy from 1998 and it still works fine.

Bill

Bill,

I think that I would reconsider the use of the glue to far beyond the shelf life that is stated. Sure, there are always exceptions to the rules.But, why spend so much time on the details of a project to then have a joint failure or table top split loose becuase of poor quailty glue? I have always been a little paranoid when it comes to this. I buy the smallest bottles I can find that way I no I always have the freshest glue I can get my paws on. The last thing I want to have happen is to finish a project only to have a leg fall off becuase the glue failed.

Donnie Raines

[Chris Knight]

I have been doing a bunch of strength tests on glue joints for a recent project. Basically making the joints, gluing them, then testing to failure with stress applied by clamps, or hammers!

It has become very clear that the type of grain to grain contact is an issue (eg is it long grain to long grain, end to long, end to end etc?) Also, in every case, whilst some wood failure takes place (ie the glue is stronger than the wood), the real issue is how the glue has wetted the wood.

So far, each glue has performed differently but Regular Titebond has done best overall.

I would emphasize that these are informal/non-scientific tests and no measurements were made, other than guesstimating the percentage of the joint that failed in the wood, versus that that failed in the glue line.

I made no attempt to regulate clamping pressures and these are clearly important - but how many of us do that when we are clamping up a project? I just tightened the clamps as I typically would in my assembly sequence. In some case, it was way too much I guess and in others, not enough.

[JayStPeter]

I usually buy glues in smaller containers to keep shelf life out of the equation. I'll buy a couple of med. size containers before a project.

Mark,
I disagree with your assessment that poly glues are messy. I find myself using poly glue to avoid mess/hassle. As a hobbiest, I often work in the shop until bedtime. Lots of times, I'll clamp up something and go to bed. I find it much easier to clean up the squeeze out of poly than titebond. I use titebond when I know I'll be able to clean up the joint within an hour later or less. I do try to use the right quantity and wipe it off initially, but there's still some latent squeeze out. I've also found that if there is a little poly glue left, finish and stains stick to it and don't leave a little white spot. If you let titebond dry hard for a week and try to scrape it out of a corner ... good possibility of white spot.
So far, I've had good luck with all my glue joints. I do test them often to ensure good technique and quantity is being used. I try to break my cutoffs over my knee to see if the joint fails or the wood. Always been the wood with both glues. What brand of poly were you using that failed so badly?

Jay

[Mike Circo]

I agree with whose who disagree with the statement that poly glues are messy.

Everyone I've seen who has a "mess" problem is using too much. You can typically use about one-third the amount of poly glue as would be used for yellow. Plus you only apply to once surface. This also stretches its use and defrays part of the higher cost.

I find that the foamed out part doesn't stick to the work and when scrapped off doesn't effect the subequent finish.

I use it when long open time is required (like for bent laminations or big glue ups), or when an odd material is used.

[Larry Browning]

If the shelf life is expired, what is it about the glue that goes bad? Is it that the glue get weaker? Is the open time reduced? Won't cure properly?? I'm with Bill on this one. I have some glue that is at least 5 years old and I can't tell the difference from new. It wouldn't surprise me to learn that the stated shelf lives are just made up times the the manufacturer puts on their products to get us to buy more glue. Have there been studies done to verify these stated times?

Hey! this could be one of those things like electric motor horsepower. I could be onto something here

[Glenn Kiso]

I stopped using gorilla glue after my benchtop started delaminating a bit here and there. Another benchtop made a year later using the same construction techniques and yellow glue is still perfect. I haven't seen the wood mag article, but I think the poly's are overrated. If titebond won't be strong enough, then epoxies are my next choice.