Are Your Glue Joints Repairable?

[Bob Smalser]

Have you tested your favorite wood glue to see if it can be reglued successfully should either your work be damaged, or a cross-grain glue joint fail with age and seasonal movement?

In 4 decades as a woodworker, I’ve done a good bit of conservation, repair and restoration work, including pieces in a few federal museums both here and overseas. As I pass what I know down to my boys, included will be what I know about glues. I know that some glue types can’t be glued over, often requiring new wood to be let in during repairs, and the joint recut. I discovered that the hard way some decades ago restoring furniture, and simply switched to other glues for all my work. Since then, those glues I rejected may have been reformulated; plus there are a number of new glues worth checking out, so to make sure I’m not providing bad or outdated advice, it’s time to check out the current crop of wood glues for repairability.

I make no pretenses toward science, here…this is all anecdotal based on experience, not chemistry…all I want to show is whether marine epoxy will adhere to the glue lines or residue of the various wood glues during repairs. You can look up strength and other test data in your USDA Wood Handbook; I care about repairability because I’ve never seen any test or even anecdotal data on anything but hide glue in that regard, and it’s important if your work is to survive beyond typical damage and wear and tear over time. I chose epoxy as the regluing agent because it’s the usual choice in professional structural repair work and it adheres to a greater number of diverse substances than any other wood glue I know of. In fact, it usually rebonds a failed but fully cured glue joint much better than the original glue would, and as it also bonds to itself very well, epoxy is a good, repairable choice for many applications.

http://pic3.picturetrail.com/VOL12/1104763/7738131/101844452.jpg

On identical tiles of freshly planed, vertical grain, second-growth Doug Fir, I saturated the faying surfaces with glue and let them cure to full strength by the manufacturer’s instructions for time and temperature….

http://pic3.picturetrail.com/VOL12/1104763/7738131/102357580.jpg

…then I keyed each faying surface with 100-grit abrasive paper, reglued them with marine epoxy, and “clamped” the assemblies to the degree favored by epoxy. For glues that left a rough surface like polyurethane, the epoxy was applied twice…an unthickened coat followed by a second coat thickened with West 404 High-Adhesive Thickener, per the manufacturer’s instructions. I let the epoxy cure for 6 days to reach full strength.

I purposely chose small blocks of wood with easily broken short grain because strength here isn’t the issue, adherence is, and I can check adherence using a sharp chisel without trying to break long glue joints in a press. Of greater concern was that the glues to be tested were applied without any clamping pressure, but as it turned out, several glues that require high clamping pressure fared very well, so I believe the results are reasonably valid.


The results offered no surprises.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102357565.jpg

The epoxy thoroughly adhered to the strongest of the off-the-shelf glues, the 2-part resorcinol, breaking completely at the wood rather than the glue line. Attempts to slip the chisel between the glue lines revealed a thorough and unified bond between all three layers of glue.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102368835.jpg

Epoxy on epoxy showed similar results……and so did liquid polyurethane (Elmer’s Ultimate)…

http://pic3.picturetrail.com/VOL12/1104763/7738131/102368841.jpg

…and powdered urea formaldehyde plastic resin glue.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102357570.jpg

Titebond, a Poly Vinyl Acetate glue, however, broke some wood but failed the chisel test…. the chisel easily separated the two layers of Titebond, indicating poor adherence of the epoxy in between.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102357764.jpg

Titebond II broke even less wood, with poor adherence…

http://pic3.picturetrail.com/VOL12/1104763/7738131/102357761.jpg

…and Titebond III, while a much stronger glue, still did not adhere to the epoxy.

The implications of all this can be minor if we are talking about a first-effort coffee table….but they can be serious if we are talking about a strip-planked boat hull made of 1 X 1 strips glued together using an unrepairable glue. Picture the requirement to feather in a large patch to repair hull damage, and you can see that patch will be pinstriped with unsound repair at every glue line, leading to early failure of the repair.

You can draw your own conclusions. Mine are that the work most easily restored is often the work that survives the longest, that you may not care about longevity, but that may break you granddaughter’s heart some day, and I’d check out my glue choices thoroughly before committing them to any 20-hour high-end project, let alone a 700-hour project.

[Don Baer]

Thanks for sharing this info Bob. Good stuff.

[Sam Blasco]

When in doubt I always reach for West System. One thing about Epoxy (or anything else) to cured Epoxy, it can't hurt to wipe it down with lacquer thinner before, re-coating or bonding. When Epoxy cures it releases amines, a wax like substance that ends up covering the surface, which could cause finishing and/or bonding problems in the next stage. Old boatmaker 'splained that to me, who also taught me my love for epoxy. make sure you work in a well vetilated area, though, when working with it. Smells rather un-offensive, almost pleasant, but can be very nasty to the respiratory system.

[Bob Smalser]

I use West because I'm thoroughly familiar with it, and as a traditional builder, I only use a gallon or so a year, so expense isn't an issue.

But System III, MAS and others make epoxies that don't suffer amine blush, which also washes off with plain soap and water.

[George Matthews]

Thanks Bob for passing along your experience. This has me re-evaluating Titebond III as my primary glue. I also use polyurethane for joints that require maximum strength. Despite other reviews, it seems to have better than average gap filling ability (foam). The down side of this glue is that the foam squeeze out is difficult to control.I suspect that others are not letting polyurethane cure long enough before performing strength tests.

I would conclude that your choice is epoxy, especially for boat building.

[Jerry Olexa]

Bob Thanks for sharing your expertise and this well supported backup to your gluing conclusion. You help us all all the time. Thanks...

[Bob Smalser]

Liquid poly isn't near as strong as epoxy and that foam may fill a gap but it provides zero strength, unlike thickened epoxy.

Personally, I use U/F resin glue in all indoor work, poly in most outdoor work and resorcinol and epoxy in boats.

These are the first bottles of Titebond I've bought in 3 decades. Nothing I know of in this world adheres to cured Titebond. And I've tried most of them.

The usual scenario was a fine, old, round-tenon chair assembled with hide glue. Hide glue is a fully-renewable glue where all you have to do to reglue the joint is soak it in fresh, hot hide glue....30 to 60 minutes to reglue the whole durn chair like new. That's why the builder used a glue that dissolves itself, as the nature of round-tenon joints is that they usually break their glue bonds every 20 years or so from seasonal movement, regardless of what glue was used.

But the owner reglued it with whatever PVA glue he had on hand...and that repair lasted a couple weeks. After a few cycles of that, he brings it to me...and it costs him big bucks, because the only way I can repair it is to steam the entire chair apart, then plug and recut the joints he contaminated with PVA.

As you can imagine, often the chair became kindling upon receipt of the estimate.

[Chris Padilla]

Hmmm, do you build now with aliphatic glues or build for the future where it might break and be easily repairable? I'm not really in the forecasting business of where a project of mine might break...I can only worry so much. I think I would prefer to focus on building high-quality with sound wood and joint choices.

Epoxies are great for what they do but they aren't the easiest glues to use and they aren't cheap...neither is poly for that matter although it appears to pass your testing.

I think an article is called for here and to get the chemists involved to see what the explanation for our favorite yellow glues failing the Smalser repairable test! :)

Thanks for the insight, Bob. :)

[Bob Smalser]

Hmmm, do you build now with aliphatic glues or build for the future where it might break and be easily repairable?

The pics don't lie, and I'm sure no Franklin International chemist will talk about it.

From my experience doing restoration work, if you are using Titebond, you are doing relatively short-lived work. Things that can't be economically reparied usually become kindling.

Every crossgrain and round tenon gluejoint in your work will eventually break its glue bond. Long grain layups last forever unless something smashes them and usually aren't as big a concern.

There are probably 20 furniture items in this house done by my hand, and an equal number of like doodads in the shop...not to mention work sold. They were all done with plastic resin, which is much cheaper than Titebond, and there hasn't been a glueline failure in the 30 years I been doing it.

But when those crossgrain joints do fail, any Granddaughter with a tube of household epoxy and an inner tube clamp can fix them for the next hundred years.

[Chris Padilla]

My eyes have been opened to the plastic resin and that is one glue I'm "getting into" for sure.

[Bob Smalser]

If you can mix a cup of cocoa, you can mix plastic resin or resorcinol. If you can pump mustard on a hot dog, you can mix epoxy.

The only down sides of plastic resin is that it likes warmer temps than PVA's....and that it has a shelf life of 1 year. As my PVA's freeze long before than, it ain't an issue with me.

[Chris Fite]

When I started building things, I never considered the implications of ignoring time. Over the years, I have developed an appreciation for time. I take seriously the duration of the life of anything that I build. Good construction, assembly, and finishing practices have moved into so much of what I build. I have found that unlike some things from the store, crafted items tend to hang around forever.

I built a set of open bookcases for a daughter over a decade ago. She showed me a picture and asked for something like this for her room. I put them together one afternoon. I figured that she would dump them when she went off to college and I could pitch them out. In reality, these cases have been to and from college, to one house after another in moving all over the country, and reside in her house now. Except for some scratches, the past 16 or so years have not done them in. Last year, my younger daughter wanted a set "just like hers". You can be sure that more time and care went into these.

I have built much furniture and fixtures for churches, so the original time frame has been pretty much forever. When I build the interior of a sanctuary, I consider that it may well be in continuous use for over 100 years. I still have all the as-built drawings for all these churches. I try to build these so that there should never need a repair short of a disaster such as a fire or tornado.

This information about glues is quite informative. I wish that I had known it all along.

I am glad we keep learning.

[Bob Smalser]

Well, the good news for PL users is that something certainly sticks to PL Premium poly construction adhesive.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102590551.jpg

Problem is, I neglected to write down whether it wuz epoxy or more PL and I'll have to run the test again.

[Larry Reimer]

Bob, thank you for the lesson on glues. I, for one, am going to pay a lot more attention to which glue I'm using where and why I'm using it. You lost me on the last post, what's PL? I appreciate your willingness to share your knowledge, Thank you.

[larry merlau]

know i have a question for ya, how does the plastic resin glue do in reguards to the finishing aspect. does the joint line show up? clean up in reguards to the surface prep for stain or clear finish. are there some tricks that you have learned in the respect that you could share? thanks in advance, i had used that plastic resin in school but hadnt since maybe the teacher was on to somethng? i figured it was just because it worked with the heater they had to dry the joints.

[Bob Smalser]

know i have a question for ya, how does the plastic resin glue do in reguards to the finishing aspect. does the joint line show up? clean up in reguards to the surface prep for stain or clear finish. are there some tricks that you have learned in the respect that you could share? thanks in advance, i had used that plastic resin in school but hadnt since maybe the teacher was on to somethng? i figured it was just because it worked with the heater they had to dry the joints.

Sands better than any glue out there and light brown color provides an invisible glue line....it is noted for both. 30-minute open time.

I don't know why it's not more popular with high-end hobbyists. What is the sense of doing traditional, repairable joinery if you stick it together with an unrepairable glue?

PL Premium is a poly construction adhesive.

[larry merlau]

Sands better than any glue out there and light brown color provides an invisible glue line....it is noted for both. 30-minute open time.

I don't know why it's not more popular with high-end hobbyists. What is the sense of doing traditional, repairable joinery if you stick it together with an unrepairable glue?

PL Premium is a poly construction adhesive.

what about clamp time, overnight or can they be removed sooner?

[Bob Smalser]

I'll have to look at the instructions.....but I almost always leave layups in the clamps over night.


Urea-Formaldehyde and Resorcinol Glues - These glues are unequaled in all around performance. They have excellent water resistance, good gap-filling properties, sand extremely well, clean up with water and have the longest open time of most glues, approximately 20 to 30 minutes. They are creep-resistant and are used extensively in structural assemblies, veneering and production furniture shops. The downside is that they require longer clamping time - usually up to 12 hours. They also are sensitive to temperature and do not cure at temperatures below 70 degrees (65 degrees for Unibond, discussed below). They need to be carefully mixed in the proper ratio of resin to catalyst. The curing process releases small amounts of formaldehyde but this is a negligible amount. Some woodworkers may find the fumes irritating so it's a good idea to use these glues in well- ventilated areas and wear gloves when using. My favorite Urea-formaldehyde glue is Unibond 800 and I use it exclusively in my veneering work. This glue is sold as a modified Urea -formaldehyde and comes packaged as a liquid resin which is mixed with a powdered catalyst. The distinct advantage of this glue is that it contains no water, which is beneficial is veneering large and complicated assemblies. The powder comes in several colors, white, tan and brown so that the hard glue will match the wood being glued. Another manufacturer, Weldwood ,sells a UF glue called Weldwood Plastic Resin and the powder is mixed with water to activate it. This is an easy glue to use and is similar to glues used to bond plywood and structural beams. Don't use this glue for veneering - water makes the veneer curl. The glue can be colored by the addition of water-soluble dyes.

Resorcinol formaldehyde glues like Weldwood, have exceptional water resistance and are used in marine applications. I don't usually use them on furniture, as the glue mixes to a dark, reddish glue line, but on hidden joints like mortise and tenons this would not be a problem.

[Martin Lutz]

Wow, talk about my brain having info overload. Great information Bob. I have a couple of questions: What are your thoughts on traditional hide glue? Do you use UF on all of your interior work, every type of joint or PVA for your long grain to long grain joints? How does UF do with expansion and contraction ie: a small sliding dovetail? I have been taught that epoxy or PVA is the more flexible aternative. This thread is tremendously informational. Thanks for sharing your experience.

Where did the above quote come from?

[Bob Smalser]

Resin is more brittle than the others, but not as brittle as hide glue...and will make any interior joint you want to make with it to perfection. Also exterior joints if you keep them painted or varnished - many thousands of varnished, coopered spars have been made with plastic resin since the 1920's with few problems providing the layup was correct and the varnish coat maintained.


Here's the data on resin:

Pot Life - 4-5hrs@70 degrees/2.5-3.5@80/1-2@90.

Open Time - 15min@70 degrees/10@80/5@90.

Closed Time - 25min@70 degrees/15@80/8@90.

Total Time to Assemble - 40min@70 degrees/25@80/13@90.

Clamp Time - 14hrs@70 degrees/8@80/5@90.



http://pic3.picturetrail.com/VOL12/1104763/7738131/102705370.jpg

Looks like I got the thick Hotstuff brand cyanoacrylate glue to adhere to the aliphatic Titebonds.

I'll do some more testing with it, but the problem is that cyano is so durn brittle that while it might repair a sliver or a layup, it is totally worthless to repair joints subject to seasonal movement or shock. One bump to that table leg and its reglued mortise and tenon joint will break again.

[Chris Padilla]

Resin is more brittle than the others, but not as brittle as hide glue...and will make any interior joint you want to make with it to perfection. Also exterior joints if you keep them painted or varnished - many thousands of varnished, coopered spars have been made with plastic resin since the 1920's with few problems providing the layup was correct and the varnish coat maintained.

I'll do some more testing with it, but the problem is that cyano is so durn brittle that while it might repair a sliver or a layup, it is totally worthless to repair joints subject to seasonal movement or shock. One bump to that table leg and its reglued mortise and tenon joint will break again.

Bob, there appears to be (perhaps) some conflicting data here. You say that the plastic resin has done well and been around a long time. That in itself is "durn" good evidence to me but then you claim it is brittle but not much as hide glue. Certainly, hide glue has been around a long time, too, and seems to have done just fine. I guess the brittleness isn't a big deal, right? The CAs appear to be too brittle.

Seems to me that aliphatic glues aren't brittle which could be why they move...they are flexible and are designed to move with the wood instead of resisting the wood movement. I guess this can be both good and bad and it may will depend on the wood species used, where it "lives", and its finish.

I guess, in the end, the plastic resin and hides are time-tested and have done fine, correct? I think the market called out for slightly "eaiser" glues to use which might be why the aliphatic glues are prevalent. You gotta mix the resin (what a pain! ;) ) and it needs >70 degrees F to cure properly (that can be painful in the winter in many areas of the US/Canada). Traditional Hide glue also needed a hot pot. Any comment on the current Hide glues in a bottle?

I guess it is easy to see why aliphatics are popular...they are simply easier to use but perhaps we gave up something for ease of application?? :)

As always, thanks for your insight.

[Bob Smalser]

I guess the brittleness isn't a big deal, right? The CAs appear to be too brittle.

Seems to me that aliphatic glues aren't brittle which could be why they move...... Traditional Hide glue also needed a hot pot. Any comment on the current Hide glues in a bottle?

I guess it is easy to see why aliphatics are popular...they are simply easier to use but perhaps we gave up something for ease of application?? :)
.

Brittleness is a huge deal!

That's why hide glues eventually break in round-tenon and crossgrain glue joints like M/T. That's also why resin glue fails outdoors....it's very water resistant, but when the finish deteriorates from neglect, the wood moves more...and that's what breaks a resin glue bond, not lack of water resistance.

Liquid hide glues work, but not as well as the real thing hot outta the pot.

Aliphatics are too flexible....that's why they creep and squeeze out of your glue joints months after the piece is done. Epoxy is the ideal for flexibility, followed by resorcinol.

Aliphatics are certainly easy, but IMO are so massively popular because few know that they can't be repaired, something many old pros like me have known since the 1950's. And why do you spose that is, eh?

You can use them if you like their convenience...but when your Granddaughter brings that treasured "heirloom" to somebody like me to fix in 60 years, she's in for some unpleasant truth. Why not fix those problems up front and save her that? Bet I don't lose any more shop time using resin than you do using aliphatics...it's all a matter of organization.

[Mike Cutler]

You definitely got me thinking here Bob. I've used the Titebond III, and Gorilla Glue almost exclusively. I think it's time I looked at the epoxies and plastic resins a little closer.
I had shied away from epoxies because I was led to believe that a loose fit was required, or that epoxies didn't fare well with tight fitting joints. Is this an urban myth or legend?
I had read about the brittleness of UF, but quite honestly never considered repairability. I'll be rethinking that decision also.
Thanks for the post, as usual it was informative, and made me rethink the things I thought I knew about.

PS. Don't get bummed out 'cause you think that people aren't paying attention or are "shouting over you". The type of posts that you make, and the information you give, are thought provoking, and will generate strong reactions, both positive and negative because they challenges someones personal belief, preconceptions or ideal.
If you make a post and 20 people disagree strongly and respond. There are probably a 100 that read the post and learned something, but just didn't respond.
Thanks for the Post again.

[Bob Smalser]

I was led to believe that a loose fit was required, or that epoxies didn't fare well with tight fitting joints. Is this an urban myth or legend?


Myth.

Even your tightest, hammered-home joint has lots of room for unthickened epoxy.

Just don't apply 500psi of clamping pressure to it.

Go to West Marine and get their free book on epoxy use. Epoxy is best applied in stages....one thin coat left to soak in a while, then a slightly-thickened coat at assembly. I a super-tight application that will require more clamping pressure than I'm comfortable with because of poor fit, I use a heat gun to thin the first coat so it seeps real deep in the wood. Gentle heat thins epoxy to the consistency of thin cyano.

[Ken Kimbrell]

You definitely got me thinking here Bob.

If you make a post and 20 people disagree strongly and respond. There are probably a 100 that read the post and learned something, but just didn't respond.
Thanks for the Post again.

Amen to that!
More of us should maybe say something, but if you are like me and don't know a lot you tend to let those that know a bit more do the talking in this kind of dialog.
One thing that you can bet on though... any time Bob Smalser posts a how-to it goes in my notebook!:D
Thanks Bob... teach away.

[Tom Saurer]

It's very sad that marketing can mute out experience. That's where places like this can have their effect.

The problem with glue, is that this issue won't be showing it's ugly head for many years. By that time people have habits and preferences ingrained.

[Chris Padilla]

Amen to that!
More of us should maybe say something, but if you are like me and don't know a lot you tend to let those that know a bit more do the talking in this kind of dialog.

You'd think that would stop yours truly but not so.... :p

[Bob Smalser]

Cyanoacrylates are the only glues that stick to Titebond residue (but are so brittle themselves that they are useless for most structural applications in wood):

http://pic3.picturetrail.com/VOL12/1104763/7738131/104008667.jpg

Epoxy sticks to 3M 5200 marine sealant:

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956083.jpg

Epoxy also sticks to PL Premium poly construction adhesive:

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956064.jpg

5200 sticks to 5200:

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956078.jpg

And PL sticks to PL:

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956073.jpg

But after only one week of soaking in 60-degree pond water, the 5200 is already begining to lose its adherence...just like I've said:

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956088.jpg

But the PL Premium glueline to the immediate right of the 5200 in the pic is behaving much more like the liquid poly to its right than it is like the 5200. I no longer think it's gonna lose adherence like the 5200 does.

We'll see by the end of the season submerged.

[Arnie Grammon]

As usual......good stuff Bob. I still think a book is in your future.

Question: Do you think that different species would give differing results? I know you used d. fir. What about spruce? Hardwoods such as walnut or alder or maple?

As for scientific validity, a well-thought-out experimental design from a life-long woodworker is much more impressive than a poorly designed experiment from a clueless knucklehead with a few M.S.'s or ph.D's attached to their name.

Arnie Grammon, M.S.

(What did I just call myself?:eek: ;) )

[Bob Smalser]

Species wil have no effect. The glue either sticks to the other glue residue, or it doesn't.

[Bill White]

I used the Resorcinol on an outdoor project several years back, and I seem to remember that it was purple. No prob since the project was to be painted. Is there a color issue with all plastic resin products? Curing time? Can it be sanded? Etc., etc.

[Bob Smalser]

Resin is noted both for its sandability and glue lines than nicely match the wood.

[Bob Smalser]

Here’s an update of interest to furniture folks.

http://pic3.picturetrail.com/VOL12/1104763/7738131/102705370.jpg

In my initial screening, I found cyano to be the only glue to stick to PVA residue – here, Titebond III.

http://pic3.picturetrail.com/VOL12/1104763/7738131/105100738.jpg

I hadn’t factored in clamping pressure. When PL Premium is clamped to PVA residue for 24 hours with high clamping pressure, it adheres well….but the glueline is soft and gummy, somewhat akin to a contact cement glueline. It appears to have potential to repair PVA-contaminated joints, so I’ll do some more tests here for repeatability and with liquid poly to perhaps see why this is.

http://pic3.picturetrail.com/VOL12/1104763/7738131/105100729.jpg

After 3 weeks in 60-degree pond water, the 3M 5200-Western Red cedar bond is beginning to lose adherence even where it received high clamping pressure.

http://pic3.picturetrail.com/VOL12/1104763/7738131/105100772.jpg

The PL Premium also has lost adherence where it wasn’t tightly clamped….but the actual joint remains sound.

http://pic3.picturetrail.com/VOL12/1104763/7738131/105100725.jpg

The epoxy has also lost adherence where it wasn’t clamped…but its joint remains sound, too.

http://pic3.picturetrail.com/VOL12/1104763/7738131/105100719.jpg

Finally, the resorcinol remains rock solid.

But you can also see from the wood color beneath the lifts, that the wood is far from fully-saturated yet.....it will need a lot more time submerged.

[Bob Smalser]

http://home.pacbell.net/ebeniste/gluearticle.htm



I'm not alone in my condemnation of PVA glues for heirlooms.

The author is over generalizing about modern glues in the second paragraph, but his repairability theme is spot on:


There are several problems associated with synthetic glues which make them unattractive to furniture makers. These problems are often overlooked in favor of the generally perceived "easy to use" features that make a ready to use product handy around the shop. One of the most overlooked problems is the most obvious: lack of reversibility. Most furniture makers today do not consider the future problems synthetic glues create when it comes time to repair their creations. However, all furniture is subject to use and damage, and all furniture needs to be repairable if it is to survive the generations. Synthetic glues cure by a catalytic conversion from one chemical to another, and are irreversible. This means to take apart furniture made with synthetic glues requires destructive intervention and physical removal of all glue prior to repair.

Modern glues have a mechanical bond only, and require tight fitting joints and even clamping. They do not bond to themselves, and set up unevenly, remaining wet in one area of the joint while setting dry in another. These glues seal the wood surface and prevent stains and finishes from penetrating evenly. They are difficult to sand and remove from the surface when set. One of the greatest problems is the lack of resistance to sheer forces, which allow the wood to "creep" along the glue joint. This "creep" allows veneer joints to open up, and solid wood joints to move over time as wood movement occurs relative to humidity and temperature fluctuations, as well as wood shrinkage due to aging.

[Jay Knepper]

Thanks for your excellent contribution, Bob.

I wonder, though, if PVA glues may not have a critical strength advantage over less elastic options where cross grain movement is an issue, such as in mortise and tenon (m/t) joints.

The reasons are:

1) Wood will move cross grain as its moisture content balances with relative humidity
2) The amount of movement is proportional to the width of the tenon, so a 4" tenon will move twice as far as a 2" tenon
3) If wood did not move, or if glues were perfectly elastic, then joint strength would be proportional to tenon width
4) PVA glues do allow creep; they are relatively elastic when cured

If the amount of wood movement exceeds the elastic limit of the glue bond, then something is going to break.

Wider tenons will make for stronger joints up to the point where wood movement starts to weaken the joint by splitting one of the members or destroying the wood-to-glue bond. I suspect that PVA glues will allow wider, and stronger, cross grain joints than less elastic options such as UF or resorcinal glues.

If I'm correct, then there may be less need to repair m/t joints that are made with PVA glues, as long as tenons are kept to a reasonable width.

[Bob Smalser]

The longevity of PVA glue isn't the big issue....more brittle glues last many decades in M/T joinery. The glue joints may break eventually, or they may not.

The big issue is repairability. If they do break....or if your piece is damaged in shipping ( probably the most common M/T glueline break)...you can't repair it without disassembly and plugging and recutting the bad joint.

That PL poly construction adhesive may have potential to repair PVA-contaminated joints economically......but a whole host of restoration folks are gonna have to use it successfully before I switch from plastic resin and hide to PVA's.

[Dennis Peacock]

OK Bob....I'm going to stick my neck out here.

I like using liquid hide glue for most of the interior pieces. I have used PVA glue a lot before and that was before I found liquid hide glue. I don't have the Hot Pot type yet....but I will one day. But my burning question is: Do you use a plastic resin glue, UF glue, or what would you use for your indoor furniture pieces? I like using epoxy, but have never used it in standard furniture building...have used it a LOT in building radio controlled airplanes.
If hide glue isn't the best and pva is good and poly is fair, then what is it to use and yes....I care about repairability and is one reason why I switched to liquid hide glue. Works very nicely.

[Mark Singer]

This is an excellent thread! I use West systems for anything outdoors and some furniture including chairs. Tightbond III is very good for normal use. I never use Poly Urethane glue...it is a mess and not reliable in strength. Plastic resin is excellent. I use Hide Glue occasionally

[Bob Smalser]

OK Bob....I'm going to stick my neck out here.

... I don't have the Hot Pot type yet....do you use a plastic resin glue, UF glue, or what would you use for your indoor furniture pieces?

Have a mason jar, a thermometer, a pan of water and a hot plate? Old electric crock pots are better.

I've used plastic resin glue in most interior furniture and boat interior applications for over 40 years. At least a 55gal drum of the powder. Never had an inside joint break with it yet. I've used hot hide glue for chairs, musical instruments, hammer veneering, and trying chipped glass decorations. When the time comes for me to do more chairs, I'll use hot hide glue. Disassembly of epoxy is problematic.

I use poly in outdoor furniture and have been replacing resin glue with it on a trial basis in interior boat applications.

I use resorcinol in boat hulls when I can live with the dark glue line and get it to the right temperature for curing (that can be difficult here)...otherwise I use epoxy.

[Martin Shupe]

Well, after reading this thread and another where KC talked about glue, I went out to the two local borgs looking for Weldwood plastic resin glue. No luck. So, do you have to mail order this stuff?, or do I need to find a good old fashioned hardware store instead of the borg? Anyone got a favorite source?

Also, I have been using "Old Brown Glue" for my joints, but PVA for long grain panel glue ups. Would hide glue be acceptable for long grain? Would plastic resin glue be better? What about joints? Hide or plastic resin?

Durability and long term repairability are both important. I want my great grandkids to fight over my furniture. (Well, I am not quite there yet, but there is hope.) :D

Great thread, Bob, you should write a book, or several!!

[Larry Reimer]

Martin, I found the same thing, or rather I didn't find the glue anyplace I went. That included a hardware store or two. I've been buying from Highland Hardware (on-line). Really like that place, great products, great service.

[Bob Smalser]

Ace Hardwares and any boatbuilder supplier like Jamestown Dist will have plastic resin.

Hide glue I get from Highland.

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/7738131/120863727.jpg

The WRC heartwood test layup that included resorcinol, West System epoxy, liquid polyurethane, 3M 5200, and PL Premium polyurethane construction adhesive was pulled from the pond water after 6 months of submersion, cleaned, and a sample removed from one end and resoaked while the large end was allowed to air dry.

http://pic3.picturetrail.com/VOL12/1104763/7738131/120863728.jpg

There were no differences in adhesion between the sample allowed to dry and the one that remained soaked.

http://pic3.picturetrail.com/VOL12/1104763/7738131/120863725.jpg

Destructive testing showed that all the products tested continued to bond strongly after 6 months of submersion. The 3M 5200 poly sealant and PL Premium poly construction adhesive, when applied without clamping pressure, lost adhesion in saturated cedar…but with a clamping pressure suitable for resorcinol, their bonds remained strong.

http://pic3.picturetrail.com/VOL12/1104763/7738131/120863724.jpg

The “saturated” cedar test layup stabilized at only 24% EMC when corrected for species and temperature. I expected a bit higher reading, but this is consistent with the 30% moisture content of cedar heartwood in the log and the 21% of submerged bilge planking protected by paint. Cedar logs do sink, however, and remain sunk long after their heavier sapwood has rotted away. So this test layup goes back in the water to see if more time will provide a higher reading. I also intend to do another layup of White Oak, which I suspect will rise to over 30% EMC with saturation.

General Notes on Glues and Goos


Resorcinol: The marine standard. If you can get 70 degrees F or higher for an overnight cure and consistent and high clamping pressure with no gaps, you won’t go wrong using it. Likes wood at 10-15% EMC, according to Navy tests. Long open time. Repairable with epoxy. Ugly red glue line.

Marine Epoxy: The repair and restoration standard. Bonds well to a wide variety of materials, and usable in almost all flexibility and temperature conditions. Needs no clamping pressure, only contact…fills gaps well. Likes wood below 12% EMC. Repairable with itself, joints can often be broken apart for repair with using heat. Clear glue line and can be dyed to match the wood. Controllable open time with different hardeners. Slightly permeable to water vapor and there are reports of failures in fully saturated wood and with White Oak. Very sensitive to UV, requiring protection.

3M 5200: A rubbery, polyurethane sealant in various colors with adhesive properties sometimes used as a glue. Fails as a glue under water saturation without high clamping pressure, and without the proper strength testing I couldn’t do here, it’s not recommended as a stand-alone marine glue. Repairable with epoxy.

Liquid Polyurethane: Gorilla Glue, Elmer’s Probond, Elmer’s Ultimate, and others. Versatile in temperature and bonding wet wood with moderate open time, these glues aren’t rated for below waterline use but initial use shows potential as a marine glue. Likes high clamping pressure and fits similar to resorcinol…it won’t fill gaps. Will successfully glue green wood at 30% EMC. Repairable with epoxy. Noticeable, yellow-brown glue lines.

PL Premium Construction Adhesive: This polyurethane goo shows promise as a marine glue with further testing and use. Works like 3M 5200 but cures and behaves like liquid poly. Appears to bond well to everything epoxy does, and more where epoxy and liquid poly won’t, perhaps because of a higher isocyanate content…it bonds to difficult surfaces only cyanoacrylate super glues will bond to. The only general-use glue I’ve found that will bond difficult aliphatic-contaminated surfaces. Appears flexible to temperature and moisture content with gap-filling ability, but as a construction adhesive, its open time is shorter than liquid poly. Appeared to like high clamping pressure, and unlike other glues, wouldn’t bond at all without at least some. Repairable with itself and epoxy. Glue line as in liquid poly.

Urea Formaldehyde Plastic Resin Glue: The old interior furniture standard, and in older marine applications that required well-blended glue lines. Still preferred by many, as it is a no-creep glue easily repaired using epoxy. Long open time, it needs tight fits and 65 degrees F or higher for an overnight cure…it doesn’t fill gaps. Best glue line among them all and moderate water resistance still make it useful for protected marine brightwork applications. A relatively brittle glue and UV sensitive, it requires protection….but its brittleness is an aid to reparability, as joints can be broken apart for repair. An inexpensive powder with a short, one-year shelf life.

The Titebond Family of Aliphatics: Convenient. No mixing, just squeeze. Short open times, fast tack, and short clamping times. Flexible in temperature and to a lesser extent in moisture content, but the bottled glue can freeze in unheated shops. A flexible glue, it has been reported to creep under load, sometimes several years after the joint was made. The latest “Titebond III” appears to be a stronger glue than its two predecessors. Difficult glues to repair, as they won’t stick to themselves and no other glues will except cyanoacrylates, which are too brittle for general use. Epoxy and fabric aren’t bonding to aliphatic glue lines in marine strip construction, compounding repair difficulties. While not definitive, the new PL Premium appears to bond well to Titebond III residue and is worth pursuing by those repairing old white and yellow aliphatic joints.

[Chris Padilla]

Anything new, Mr. Smalser? :)

[Mark Rios]

Thanks for bumping this up Chris. I missed it the first time around.

Bob, what glue then would be recommended for cutting boards, kitchen utensils and the like?

[Bob Smalser]

The cedar I'm testing isn't as saturated as it can get, yet.

I'd use a liguid poly for kitchen items....Elmer's Probond, etc. Likes wet and much more repairable than Titebond.

[Bob Marino]

The cedar I'm testing isn't as saturated as it can get, yet.

I'd use a liguid poly for kitchen items....Elmer's Probond, etc. Likes wet and much more repairable than Titebond.
Bob,

Glad to see you back here!

Bob

[Don Baer]

Hey Bob,
I started using Probond a few months ago and realy like it. It seems to allow a little more time for glueup then tightbond also. Have you found this to be true ?

[Bob Smalser]

I'm pretty busy this summer, so I haven't been around.

Another major advantage of poly is that if you catch it within 12 hours when the residue is firm but not rock-hard, you can run the boards thru the planer without tedious scraping like in other glues.

I've switched to PL Premium Construction adhesive for all of my outdoor work that doesn't call for either epoxy or resorcinol. Incredibly strong stuff and will stick to most anything, including Titebond.

http://pic20.picturetrail.com/VOL12/1104763/3297171/163774745.jpg

Had a few days between concrete pours last week and whipped together a set of French Doors for the shop. 2" Western Red Cedar, routered slip tenons and PL Premium. Cedar makes an ideal door providing you add brass kick plates and bolts instead of screws for the hinges.

[Norman Hitt]

Bob, I'd been wondering about you and where you'd been for the last week or so, but guessed that you had just been too busy "House Building" and maybe "Boat Repairing" to make an appearance here. How's the House coming along? How about a few pics of your Summer's activities when you get time? We've Missed your Posts, as they are always interesting, informative and educational. I hope all your projects are going well.

Best Regards.........Norm

[Chris Padilla]

Good to hear from you again, Bob...write when you can! :)

[Gary Herrmann]

Looks like I should have read this before I made the umbrella table.

[Chris Padilla]

Better late than never? Gary, this was buried in the past here on SMC so I brought it to light when I was looking for some other stuff. I wonder if this thread deserves a sticky on the forum or perhaps moved somewhere where it can be found easily??

[Howie French]

Just a bump for a very interesting thread.

Thanks for posting Bob, your postings are very informative.

Howie

[josh bjork]

Cool, i appreciate the topic. In bow making, Urac 185 is thought to be one of the best wood to wood glues. It is in the same class with Recorsinol and Weldwood. It is an old glue formula, I think it is phenol based and it seems to have filler in it and it is one of the best gap filling-low clamp pressure glues in terms of strength for Bowyery. And it is pretty cheap.

I've made a bow with hide glue and the stuff is amazing in its own way. It shrinks some when it cures and that can be an advantage if you use it to make a bow at least. I used Knox gelatin. The stuff you buy in bottles isn't as strong as real hide glue. Knox is refined hide glue and in tests I've seen, stronger than lesser forms of this glue. It is very fun to use though somewhat messy. People use coffee cup warmers and other silly items to keep the glue warm, not high investment or high tech.

Bob, I've seen a glue test and wish I could refer you to it. The guy glued down little blocks of wood maybe 1/2" squares and then put a wrench on them and using a scale, recorded what poundage it took to break them off. It was cool to see the glues in respect to each other, and you can then draw further conclusions from that data. Like glues that are strong but not suitable for tasks or whatever limitations they have besides strength.

This is a good talk.

[Don Bullock]

...Great thread, Bob, you should write a book, or several!!

I fully agree. This is great information for me as I get back into woodworking. Thanks to Bob and everyone else that has contributed to this thread.

[Cliff Rohrabacher]

If you really care that someone will be able to repair your work after you are out of the picture try marking your work in a way that reveals the glues used.

It is really quite easy to determine what glue was used by either tasting the glue or burning a tiny bit with a match or hand held lighter and smelling the smoke.
Set the sample on tin foil and cook it off.

Mopst all polymers smell quite differently when burned. Hide smells and tastes different than rice or albumin glues. each molecule gives off different combustion compounds when cooked off.

The matter becomes somewhat more complex when one is trying to differentiate between very similar epoxies.

[John Schreiber]

Fascinating thread. Thanks for bumping it up. I'll have to study it to see if I should change any of my practices.

[Andrew Shaber]

Great thread. I had never thought about repairability.

It would be useful to see a guideline come together. I will probably always use PVA for shop fixtures/jigs etc because I like the convenience.

long edge jointing, especially with biscuits: PVA? quick simple, biscuit would be moved in a repair etc...

M&T: more likely found in quality work so repair is more likely. which to use?

etc etc....

[Bob Smalser]

...Bob, I've seen a glue test and wish I could refer you to it. The guy glued down little blocks of wood maybe 1/2" squares and then put a wrench on them and using a scale, recorded what poundage it took to break them off.

As most glues are stronger than the wood they are gluing, he measured the sheer strength of various blocks of wood to a greater degree than he measured glue strength.

http://pic20.picturetrail.com/VOL12/1104763/7738131/103956078.jpg



Great thread. I had never thought about repairability.

It would be useful to see a guideline come together. I will probably always use PVA for shop fixtures/jigs etc because I like the convenience.

long edge joining, especially with biscuits: PVA? quick simple, biscuit would be moved in a repair etc...

M&T: more likely found in quality work so repair is more likely. which to use?


That's why I did the article. I got tired of getting beat up every time I mentioned that the most popular PVA glues have some major problems with them.

PVA's are fine for edgejoining, as those joints should last forever because of identical seasonal movement across the glue joint. I've had roughsawn panel glueups in and out of the clamps and thru the planer within an hour in heated shops. The exception is if the panel is structural and must withstand a load. PVA's remain plastic and can creep under load years later, causing proud edges, regardless of any biscuits used.

Moreover, unless it's a huge or odd-shaped layup requiring alignment aids, biscuits, dowels, or splines are a waste of effort, as the glue alone is sufficient. Bronze or galvy drifts are another matter in some structural applications in boats.

I use and recommend UF resin glue (Weldwood or DAP...URAC is easier to use but hard to find) for furniture, hot hide glue for chairs and other round tenon applications, and polyurethane or marine epoxy for outdoor joinery. Epoxy has been found to fail gluing White Oak in marine applications and resorcinol remains a better choice for oak.

But other factors are involved. High moisture content wood (over 15%) requires polyurethane. UF and resorcinol require 70 degrees to cure and I often have to resort to heat blankets. Open time can be critical....and PVA and poly construction adhesive have short open times that get worse in warm weather. Only epoxy fills gaps well, although URAC is better than most.

Strength is the least concern. All of them are sufficiently strong within their application parameters.

[Montgomery Scott]

Bob,

Do the plastic resin glues require a higher temp to sure or will they cure in colder temps, but take longer to do so? I live just north of Everett so winter time presents the problems of lower temps in my shop (~50F).

How well does plastic resin glue work for woods in the dalbergia genus? I have not been real happy with any glue for segmented turning. Epoxy can leave a thicker glue line than I like (I've used System 3), I've had PU glues separate before, though the couple of failures I've had may be due to some of the wood having a MC that was >10% and was still shrinking and I've experienced the glue creek of PVA's.

[Bob Smalser]

Bob,

Do the plastic resin glues require a higher temp to sure or will they cure in colder temps, but take longer to do so? I live just north of Everett so winter time presents the problems of lower temps in my shop (~50F).

How well does plastic resin glue work for woods in the dalbergia genus? I have not been real happy with any glue for segmented turning. Epoxy can leave a thicker glue line than I like (I've used System 3), I've had PU glues separate before, though the couple of failures I've had may be due to some of the wood having a MC that was >10% and was still shrinking and I've experienced the glue creek of PVA's.

They won't cure in cold temperatures, period. Neither will epoxy, BTW....it'll harden, but of you test it you'll find it's not as strong. 70 degrees for resin (URAC was developed to have a wider temperature range and to fill gaps), and at least 50 degrees for epoxy. Go to Goodwill and buy an old heat blanket when in doubt.

Cocobolo and other tropicals can be hard to glue, even with resorcinol, because of oil, and it can vary from board to board. Smith Enterprises of Rot Doctor fame claims to have an epoxy formulated specifically for tropicals. But I'd prefer resin for your turnings because it has the cleanest glue line of all of them by far. I'd test it on some freshly-planed scraps, alternating whether you wipe first with acetone or not.

[Mike Cutler]

Cocobolo and other tropicals can be hard to glue, even with resorcinol, because of oil, and it can vary from board to board. Smith Enterprises of Rot Doctor fame claims to have an epoxy formulated specifically for tropicals.

Hmm... I have a cocobola project in the near future. I had planned to use System 3 epoxy. I'll have to check out "Smith Enterprises line. I think I saw Rot Doctor demo'd at a home show. Thanks for the info Bob.

[Freddie Murray]

I'm sure Bob Smalser knows 100 times more than I do about woodworking and has probably 1000 times more experience. However, my 3-decade experience using almost nothing but the original Titebond is far different from what he suggests. I have had 100% success with Titebond--no joint failures, including plenty of cross-grain and M/T, no creep, and no oozing.

I decided to do some experiments of my own. I started by coating a few small pieces of #2 pine with a thin coat of Titebond after sanding each piece with 100-grit sandpaper to create a uniform and clean surface. After that glue had cured, I put on another coat on 1/2 the pieces. The single-coat left a rough surface because not much glue was left at the surface, and the double-coated surfaces were slick and smooth.

Then I glued a few of the double-coated pieces to each other with no preparation. After drying, I tested them, and in all cases the wood broke before the glue joint let go. However, pine is pretty weak, so I did a more difficult test. I put a blob of Titebond on two double-coated surfaces--one sanded, and one untouched. After drying I used a chisel to see if I could cleave the blob from the underlying surface. Sure enough, I could, indicating a weak bond.

Before giving up I tried one more thing. I put a layer of water on a double-coated surface and let it sit for a while. The Titebond on the surface turned milky in appearance. It also softened up and became somewhat tacky. I put a couple of blobs of Titebond on the softened surface and let everything dry. The chisel test showed total success. The Titebond seemed to have fused together, and the blobs would not cleave off the underlying surface. My tentative conclusion is that the original Titebond, because it is water soluble, can be repaired with itself as long as the original glue in the joint is presoftened with water.

Then I did an experiment to test the theory that Titebond does not cure hard enough and oozes out of joints. I put a thick 2-inch long stripe of Titebond on a piece of shiny tape, and then did the same with liquid hide glue. I set them on my boiler, where it gets comfortably warm, and let them dry for 3 days. I removed them from the tape and did two tests to check their comparative hardness. I placed a sharp scribe against each glue blob in several places and balanced a 5-pound weight on the scribe. Then under high magnification, I looked to see if the scribe penetrated more deeply in the Titebond or the hide glue. It penetrated the hide glue more deeply.


Then I did an even less scientific test. I put the Titebond piece in my vise and squeezed gently. Then I did the same with the hide piece. Jaw marks were clearly seen in the hide glue, but not in the Titebond. The Titebond was significantly harder than the hide glue. I then bent each glue piece until it broke. Both pieces broke with a clean snap, but the Titebond took much more force. In this experiment the Titebond proved, harder, more rigid, and stronger.

Will Titebond ooze out of a joint? Something would have to be very strange for that to happen. Will it allow creep? Given that it appears to be harder and stronger than liquid hide glue, that doesn't seem very likely.

Here's a real quick experiment that I did that you can easily do. Take two pieces of wood, spread Titebond on one, and clamp them together as if to make a permanent joint. Wait about 20 minutes and pull them apart and let them dry. Do you see any glue that could ooze? A well-clamped, tight-fitting glue joint is so thin, the glue would be largely constrained by the wood. What's to creep?

[Martin Shupe]

Welcome to the Creek.

This month's FWW has an article on glue, including my favorite, "Old Brown Glue". I have only skimmed it, but it should be interesting reading.

This is an old thread, and I don't have time right now to read it again, but as I recall, it contained good information.

Hide glue is used to build chairs. Eventually, all chair joints will fail. When they do, you may use hide glue to repair them, as hide glue will stick to itself.
I don't think you can say that about PVA. I have also heard of epoxy being used for chairs, but I have no experience in that area.

As far as glue creep is concerned, while I have not experienced it, I have talked to people who have.

I respect Bob Smalser's opinion on most things having to do with woodworking. My only regret is that he has yet to find the time to put all of his excellent information into a book.

Again, welcome, and I look forward to your input.

[Freddie Murray]

Welcome to the Creek.


As far as glue creep is concerned, while I have not experienced it, I have talked to people who have.

I respect Bob Smalser's opinion on most things having to do with woodworking. My only regret is that he has yet to find the time to put all of his excellent information into a book.

Again, welcome, and I look forward to your input.

Thanks for the welcome, Martin. I'm sure people have experienced creep in joints, but there has to be something going on in those joints that is not normal. Perhaps it's certain species of wood that are oily or something else that is unusual. Almost all my experience is with pine, red oak, rock maple, and walnut. Maybe it's some kind of contamination. I don't have the answer, but after playing with a cured bead of Titebond and seeing how hard it is, I just can't see how Titebond would ever creep under normal circumstances, let alone ooze out of a joint. You're right, Bob Smalser has probably forgotten more than most of us will know about woodworking. I hope he has a chance to add to this thread.

[Mike Henderson]

I always thought of creep as the movement (due to stress) of two pieces of wood that are glued together. That is, if two pieces of wood are glued together and then two forces are applied to the pieces parallel to the glue joint but opposite in direction (one force to each board), the two boards will move slightly over time in relation to each other. That is, they will "slip" relative to each other.

I know Titebond acknowledges that their glue has some creep, and they view it as a good thing to accomodate the natural seasonal movement of wood.

However, like you, I would think that if the glue joint is very thin, the creep will be very small unless the glue slips against the wood. So my question would be "Is creep the deformation of the cured glue, or the slipage of the wood against the glue?"

You raise some good points and have done some good experiments to try to find answers to your questions. Welcome to the board.

Mike

[Joel Goodman]

What about collecting Bob's posts and making a book out of them? I bet a lotta folks would buy it -- I would. Thanks for the great info. I'm changing my glue choices as a result of this thread.

[Bob Smalser]

... However, my 3-decade experience using almost nothing but the original Titebond is far different from what he suggests. I have had 100% success with Titebond--no joint failures, including plenty of cross-grain and M/T, no creep, and no oozing.



I use Titebond, too. No other glue allows me to lay up a roughcut panel and have it cure adequately to run thru the planer in an hour.

But the only glues I've found that glue over its residue with any longevity are cyanos. But thin cyano is way too brittle for longevity, and high-cyano-content PL Premium poly construction adhesive shows more promise.

And it certainly can creep under load, long after curing, and even the manufacturer says so...there are better choices for joints under a continuous load.

There are a dozen good glues out there, all with significant strengths and weaknesses for any given application. I have most of them in my shop, and use them accordingly. Limiting yourself to one or two all-purpose glues is kinda like saying one solution solves all problems. It doesn't. The worst horror story in restoration work is a priceless antique chair with round tenon joints originally done in hot hide glue but later glued over several times using aliphatics. Those folks all sanded the joints too before applying more Titebond, but all they were really doing in a round tenon joint so sensitive to seasonal movement was setting themselves up for another fall.

[Pete Bradley]

...after playing with a cured bead of Titebond and seeing how hard it is, I just can't see how Titebond would ever creep under normal circumstances...

Hardness is not an indicator of creep resistance. Creep is a long-term reaction to continuous stress. From Titebond's site:

"All PVA glues are prone to "creep" or slowly stretch under long term loads, and are not recommended for structural applications."


Pete

[Randy Klein]

Not to resurrect an old thread, but since I happened upon this one...

Both FWW and Wood have recently done articles about glue and if I recall, they both chose TB III as the "best" (whatever "best" was, I forget).

Just wondering if you, Bob, have seen the articles and can comment on them.

[Bob Smalser]

Just wondering if you, Bob, have seen the articles and can comment on them.

No, I rarely read those magazines unless I have something in them.

Those authors and I simply have different priorities. Bet they didn't look at repairability at all, did they? Nor did they wait two years to see if any of those joints creeped. You can't glue over any of these aliphatic residues if the glue joint breaks down the road, you often have to recut the joint. Seems like I've spent half my woodworking life cleaning up the messes of short-sighted craftsmen and boatbuilders, and I have no intention of someone 60 years from now cussing my work 'cause I wasn't thinking past my nose.

I'm still in the process of using up the bottle of TBIII I bought....it does have some good applications. Panel layups are one of them. But only if you can take down the glue squeezeout in a planer after scraping. Other than that I don't see any difference. Gummy glue lines impossible to sand and ruining the stain, unrepairable joints, but hopefully not the disappointment of one board of the panel suddenly standing proud from its mates a few years down the road.

[Randy Klein]

Saw this on another forum, David Marks comments (http://www.djmarks.com/pdf/ureaglue.pdf) on Plastic Resin glue and he mentions the FWW article...

[Al Willits]

"""""""""
Personally, I use U/F resin glue in all indoor work, poly in most outdoor work and resorcinol and epoxy in boats.
"""""""

Ok, major information overload here, I understand epoxies...well, maybe not understand, but I have used them a little, and I use Titebond 3 a lot and it seems to work ok, but seems there may be better glues to use.

But....

If someone is really bored, can they give me a few brand name of U/F resin glue, poly and resorcinol.
Also it was stated that resorcinol needs appox 70 degree's to cure correctly?
I live in Minn and my shop/garage rarely gets above 65 during the winter, should I not use it?

Considering I don't work on boats, leastwise wood ones, I think I'll try epoxy for outdoors and U/F (whatever that is) for indoors??

It would be nice to try several different types of glues, just not sure which brands to buy.
Great posts, thanks.

tia

[Randy Klein]

"""""""""
Personally, I use U/F resin glue in all indoor work, poly in most outdoor work and resorcinol and epoxy in boats.
"""""""

Ok, major information overload here, I understand epoxies...well, maybe not understand, but I have used them a little, and I use Titebond 3 a lot and it seems to work ok, but seems there may be better glues to use.

But....

If someone is really bored, can they give me a few brand name of U/F resin glue, poly and resorcinol.
Also it was stated that resorcinol needs appox 70 degree's to cure correctly?
I live in Minn and my shop/garage rarely gets above 65 during the winter, should I not use it?

Considering I don't work on boats, leastwise wood ones, I think I'll try epoxy for outdoors and U/F (whatever that is) for indoors??

It would be nice to try several different types of glues, just not sure which brands to buy.
Great posts, thanks.

tia


Al, the article I posted a link to covers some of your questions. Take a read.

He mentions several brand names for plastic resin and where to purchase.

As for temps, David Marks says if your shop is too cold, you can cover your glue-up with plastic and put a ceramic heater in there while it cures. This way you don't have to heat your whole shop. Granted, I haven't done this yet, so no idea of success.

[Bob Smalser]

Buy an old heat blanket at Goodwill, and temperature won't be a problem.

[Al Willits]

Thanks, looks like the Weldwood is gonna be the easist to get, but I'll check into it.
Also wondering what would be wrong with using epoxies for outside work, like flower boxes, garden furniture and such?

Not to fond of the heating required thing, but we'll see.

Not exactly ready to throw out the titebond 3 yet, but always looking for new/better ways of doing things.

Although, peeling the titebond off the fingers gave me something to do while the glue dried on whatever I was working on....:D

Once again, thanks.

Al

[Bill Brehme]

Super thread as usual Bob, of course this thread was started some time ago, as usual it popped up just in time (almost) to answer a problem I ran into... I'm making legs for a sawhorse which are 2 boards long grain glued together w/ 1/2 mortises hogged out of each board like a trestle table base to form a complete mortise. I've already glued the two boards together w/ TB III and evidently did not use enough clamping pressure and have a hairline gap in between.:mad: I was trying to think of a way to fill in the gap. Dumb instinct told me not to fill w/ more TB III (whew):o . And I was considering Epoxy just before I read this. Any suggestions for a filler? Anyone?:confused:

[Randy Klein]

I've used plastic resin glue in most interior furniture and boat interior applications for over 40 years. At least a 55gal drum of the powder. Never had an inside joint break with it yet. I've used hot hide glue for chairs, musical instruments, hammer veneering, and trying chipped glass decorations. When the time comes for me to do more chairs, I'll use hot hide glue. Disassembly of epoxy is problematic.

Since I love rehashing old, but great, threads...

Bob, I was wondering why you use hide glue, instead of plastic resin for chairs? Is it because chair joints break/loosen more often than traditional furniture joints and hot hide glue is an easier repair when this happens?

Also, have you done any of this testing with urea-modified hide glue and/or what is your opinion of adding urea to hide glue?

Lastly, you mentioned before that you may be switching to poly for indoor work. Is this still true? Do you have an updated opinion? And is the poly you refer to Gorilla Glue (or Titebond equivalent) or the PL stuff?

[Jack Briggs]

I use hide glue all the time, so yes - my glue joints are repairable!;)



Cheers,

[Bob Smalser]

Since I love rehashing old, but great, threads...

Bob, I was wondering why you use hide glue, instead of plastic resin for chairs? Is it because chair joints break/loosen more often than traditional furniture joints and hot hide glue is an easier repair when this happens?

Also, have you done any of this testing with urea-modified hide glue and/or what is your opinion of adding urea to hide glue?

Lastly, you mentioned before that you may be switching to poly for indoor work. Is this still true? Do you have an updated opinion? And is the poly you refer to Gorilla Glue (or Titebond equivalent) or the PL stuff?

All round tenon joints eventually break from seasonal movement tyrning the tenon into an oval with little glue contact. Hide glue is easily renewable. The modern production solution is thickened epoxy but heaven help you if one the joints does eventually break, as you may destroy the assembly trying to dismantle it to get at the failed joint.

I don't see any reason to mix glues. While hide glue is very strong, glue strength is an overrated misnomer, as glues only have to be as strong as the wood surface they are in contact with. All of them are unless operator headspace comes into play like when I once glued up a barn door in a driving rain using poly and found the limits for how much water poly likes.

I still use UF resin for interior work and PL Premium, marine epoxy or resorcinol for exterior work, depending on what it is. One addition to the article would be that liquid poly like Gorilla Glue is useful for hot applications like laminating strips straight out of the steambox that are too hot for epoxy. The test boat where I used liquiid poly instead of epoxy for all the laminations still sits out in the weather year-round and has no problems after 4 years of it.

[Randy Klein]

I don't see any reason to mix glues.

Bob, thanks for the reply.

However, I think you misunderstood my second question regarding urea-modified hide glue.

I didn't mean mixing UF resin glue with hide, but adding urea to hot hide glue (to extend open time), essentially making liquid hide glue or Old Brown Glue from Patrick Edwards.

[Brian Penning]

I'm glad this post was resurrected.
Been doing a lot of repairs as of late and knowing now that epoxy bonds so well to old glue it'll help in that I don't have to remove so much of the old glue as I have been.

[Brian Kent]

I had set aside a planned project, but it may be resurrected now:

A white oak lutyen's bench, made in southern california where I can find 70° days often. It will be outside but under a porch. Mostly dry, short humid rainy season, temps between 30 and 110°.

What I am reading here tells me to use:

1) Resorcinol, or

2) Marine Epoxy.

Did I get that right?

[Al Navas]

Brian,

Did you ever build the lutyen's bench? And, if you did, which glue did you use?

Also, a bump for this thread, as others may also be interested in the information herein...:D


.

[Bob Smalser]

I'm only moving this to the last page where it's handier to refer folks to.

General Notes on Glues and Goos


Resorcinol: The marine standard. If you can get 70 degrees F or higher for an overnight cure and consistent and high clamping pressure with no gaps, you won’t go wrong using it. Cover it overnight with an electric blanket to make sure. Likes wood at 10-15% EMC, according to Navy tests. Long open time. Repairable with epoxy. Ugly red glue line.

Marine Epoxy: The repair and restoration standard. Bonds well to a wide variety of materials, and usable in almost all flexibility and temperature conditions. Needs no clamping pressure, only contact…fills gaps well. Likes wood below 12% EMC. Repairable with itself, joints can often be broken apart for repair with using heat. Clear glue line and can be dyed to match the wood. Controllable open time with different hardeners. Slightly permeable to water vapor and there are reports of failures in fully saturated wood and with White Oak. Very sensitive to UV, requiring protection, and doesn't like heat. If you are scarfing planks that will require steambending, use resorcinol instead.

3M 5200: A rubbery, polyurethane sealant in various colors with adhesive properties sometimes used as a glue. Fails as a glue under water saturation without high clamping pressure, and without the proper strength testing I couldn’t do here, it’s not recommended as a stand-alone marine glue. Repairable with epoxy.

Liquid Polyurethane: Gorilla Glue, Elmer’s Probond, Elmer’s Ultimate, and others. Versatile in temperature and bonding wet wood with moderate open time, these glues aren’t rated for below waterline use but initial use shows potential as a marine glue. Likes high clamping pressure and fits similar to resorcinol…it won’t fill gaps. Will successfully glue green wood at 30% EMC. Repairable with epoxy. Doesn't mind heat...poly can be used to glue steamed laminations without cooling them first. Noticeable, yellow-brown glue lines.

PL Premium Construction Adhesive: This polyurethane goo shows promise as a marine glue with further testing and use. Works like 3M 5200 but cures and behaves like liquid poly. Appears to bond well to everything epoxy does, and more where epoxy and liquid poly won’t, perhaps because of a higher isocyanate content…it bonds to difficult surfaces only cyanoacrylate super glues will bond to. The only general-use glue I’ve found that will bond difficult aliphatic-contaminated surfaces. Appears flexible to temperature and moisture content with gap-filling ability, but as a construction adhesive, its open time is shorter than liquid poly. Appeared to like high clamping pressure, and unlike other glues, wouldn’t bond at all without at least some. Repairable with itself and epoxy. Glue line as in liquid poly.

Urea Formaldehyde Plastic Resin Glue: The old interior furniture standard, and in older marine applications that required well-blended glue lines. Still preferred by many, as it is a no-creep glue easily repaired using epoxy. Long open time, it needs tight fits and 65 degrees F or higher for an overnight cure…it doesn’t fill gaps. Best glue line among them all and moderate water resistance still make it useful for protected marine brightwork applications. A relatively brittle glue and UV sensitive, it requires protection….but its brittleness is an aid to reparability, as joints can be broken apart for repair. An inexpensive powder with a short, one-year shelf life.

The Titebond Family of Aliphatics: Convenient. No mixing, just squeeze. Short open times, fast tack, and short clamping times. Flexible in temperature and to a lesser extent in moisture content, but the bottled glue can freeze in unheated shops. A flexible glue, it has been reported to creep under load, sometimes several years after the joint was made. The latest “Titebond III” appears to be a stronger glue than its two predecessors. Difficult glues to repair, as they won’t stick to themselves and no other glues will except cyanoacrylates, which are too brittle for general use. Epoxy and fabric aren’t bonding to aliphatic glue lines in marine strip construction, compounding repair difficulties. While not definitive, the new PL Premium appears to bond well to Titebond III residue and is worth pursuing by those repairing old white and yellow aliphatic joints.[/QUOTE]

[Eiji Fuller]

Just wanted to bump this very informative thread!