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Seems as if a lot of woodworkers think that epoxy is a panacea for any woodworking problem with out really understanding it's properties. I see it frequently reported that someone has used epoxy for this or that and it is really not the best glue for the application. Now I realize that some of the folks that use it for fret boards have carefully considered their reasons and reasoning but it seems as if a lot of other folks are jumping in without thinking about it.
I have questions about the use of epoxy on fret boards.
Why epoxy. Epoxy does not dry hard, it can be almost rubbery. Add to that the fact that it likes and tends to create a thick glue line and it seems that it would have a dampening effect between the fret board and neck. Maybe that is not bad. In light of the concern for the use of hide glue and "sonic" glues it would seem to me that epoxy is the least sonic of the glues we would use. Again maybe not a problem. People talk of not introducing water into the fret board neck joint. That seems to me the least of the problems. You are gluing to very different woods with different densities, t/r ratios, thicknesses together in a unbalanced construction. I understand we have to do it but I would never do this in a piece of fine woodworking. The fact is there are inherent or potential problems with this kind of construction. My point being that one could have issues no matter what glue one used. I also wonder how much water there is in a very thin glue line of LMI, hide, yellow and how long it takes for that to dissipate. I wipe water on work all the time and it doesn't warp anything. A lot of people report neck warping but I wonder if it is because of the glue. I know several high profile very good builders that use yellow and white glue on the fret board with out problems of warping. How thick you leave the neck, when you shape it, how long you leave it clamped etc. There are a lot of variables.
I want to discuss this. I think it bears discussion. It seems as if people get very fervent when talking about glue. They seemed very attached to their favorite glues (Pun intended) I am not trying to step on anyone's favorite glue or method. I have thought about this a lot and it keeps coming up. A lot of people are saying "great I am going to try epoxy on my next neck" whether they have had issues or not. No one seems to be questioning this.
One thing to remember is that someone who knows how to use any type of glue well and make a good joint will do better than someone using the best glue ever invented if they use it poorly.
Link

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Cut to size.....Beat to fit.....Paint to match.

If clamped properly there will be no visible line and if good epoxy is used the bond will be great. The real benefit is that epoxy does not introduce any undesired moisture into the neck which could otherwise cause warping.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

In my experience, the epoxy cures very hard. I always have some extra left over in the cup when I get done, and I always check the cure of the leftover. It is always very hard. I've only seen epoxy cure rubbery when thinned with alcohol.

I don't get a visible glue line. I'm sure the glue line is, in fact, thicker than it would be with Titebond or whatever, but it still appears to be plenty thin enough. I have no concern at all about damping. In general, I don't buy into that argument with regard to glue anywhere on the instrument.

The way I see it, with the unavoidable factors that can cause warping in the neck, why add one more potential factor (water spread over such a large surface) when it isn't necessary? Even if it would be fine most of the time. I've taken the advice of people who've built or overseen the building (in production situations) of a lot more guitars than myself, that the water can, and occasionally does, cause problems.

I also really like the long open time with slow setting epoxy. The FB and neck are big surfaces. It can take a little while to spread the glue and clamp up, and occasionally something can happen like having a little difficulty getting the alignment pins to find their holes or whatever. I don't want to have to worry at all about having a weak bond because of too much open time, and I like being able to do the job in a completely relaxed way.

Finally, again due to the large surfaces, using a glue with some gap filling ability makes sense to me, even though my surfaces are carefully prepared and for all intents and purposes gap-free. It's a big area to clamp, and you have to use a lot of heavy clamping with Titebond. With epoxy, I just pop on a row of spring clamps along each edge, plus a few cam clamps in the heel area, and I know I've got a good joint.

That's my story and I'm sticking to it (pun intended)!

Good questions, Link. And, as with anything, different methods will work well for different people. For me, epoxy is working great in this application.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

I use yellow glue and I have used hide glue on my first build without any issue. If backbow is such a concern then clamp the neck in a curve while gluing, the naturally backbowed fretboard (if fret is installed before gluing) will cancel the bowed neck resulting in a straight neck. Epoxy doesn't release with heat while some might release with heat it will most likely release tons of harmful chemicals in the process and then you're left with cleaning off the leftover before reguling, and epoxy is not the easiest adhesive to clean off. Most epoxy won't soften enough to allow release of the parts without damage unless the joint is heated to the point of the wood turning into charcoal, because epoxies are generally meant to be used with metals and composites and most of their application deals with very high temperature. Like I said epoxy is great for joints that doesn't exactly fit so if your fingerboard to neck fit is so poor that there are gaps then epoxy is a great choice. Hide glue is great in my opinion if the joint is perfect and glue is used properly, if the joint needed to be separated in the future for repairs only a little heat/steam is needed and then all you have to do is add more glue and clamp, and even if you had to clean off the hide glue to make things fit better they come off like glass.

I never had warped neck due to moisture in the glue. Many major manufacturer used yellow glue including Warmoth, Taylor, and many others and they never had serious problem.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Myself I have used only fish glue on my 4 builds so far, without any significant backbow, but I always had the neck at full blank thickness and width (almost 1" thick, 2.5" wide) for the process, and only carved it after, as the very last step of the build.

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Build log

I use titebond for all my fretboards and have never had a warp problem due to moisture in the glue.The area or thickness of the glue joint when useing titebond is so small compared to the thickness of the neck and fretboard that warping isn't an issue when useing it.I do use epoxy on inlay work because of the difference in material being glued, but that's all i use it for.I would never use epoxy for anything that might have to be removed in the future including fretboards.

The moisture-resulting-in-neck-bow issue is most easily seen on electric guitar necks - electric players generally demand lower action than 85% of acoustic players, and when you're trying to get the lowest action possible you start to notice stuff like this.

I also include carbon fiber rods in my neck construction, which I think keeps the whole neck more stable against temp and humidity changes - and the more stable you make everything, the less likely you are to need regular truss rod tweeks, and so the less likely you are to be in the position of having to remove the fretboard down the road (figuring here that truss rod problems are the #1 reason to remove the board).

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The member formerly known as erikbojerik....

Link...this is a great subject and I applaud you for initiating the thread. We often get set in our ways and rarely question methods until a fine woodworker such as yourself questions practices and adds credence to the debate. I'm always interested in learning tricks from other woodworking applications.

I started using epoxy 6 years ago after gluing my first FB to a plain serviced Martin neck with HHG. It was my first guitar and I was determined to use HHG on every joint, erroneously thinking that I should adhere to the tradition of the ages. In spite of using my best efforts at the time, I ended up with a significant backbow with a single-action Martin TR that could do nothing to reverse the bend. Ultimately, sanding and leveling solved the issue but from that time onward, I elected to use non-moisture-containing glue (Epoxy).

Fast forward to today where after experimenting unsuccessfully with several hardware store variations of epoxy, I have settled on the Bob Smith 30 minute epoxy that is found in Hobby Stores. This stuff, along with West Systems and System III cure as hard or harder that the traditional Yellow or White wood glues and not only have produced quality thin joint lines but they are also reversible with heat. Since going to epoxy, I have never experienced a neck warp in either acoustic nor electric necks. I also use 2 CF rods as well which surely adds to the stiffness and stability.

But your post did jog a few thoughts loose that I'd like to explore with you and others as well. For the past 5 years, I have been making up my own neck blocks incorporating the 5-piece laminate method. The glueups end up being about 27"x3"x4" and are aged for months before being bandsawn into 2 neck blanks. The 2 major bookmatched mahogany components are perfectly square and jointed flat before the glueup. And why can I use Titebond in these blocks without having issues with moisture warping? Is it because the volume of wood is greater in proportion to the glue used...is it the laminations adding more strength to the layup...or what? Here's my current hypothesis...After months of sitting around following glueup, it's always necessary to plane them back to square before bandsawing. In addition, as a neck blank, they sit around at least another few months where they further move and stabilize. I know this because I always need to joint the FB surface and get it perfectly flat prior to final neck carving and gluing on the FB. I then glue on the FB after all of the square milling is completed and the initial taper is established...about 75% carved out. So I believe I am also seeing the effects of moisture warping these neck blanks as well...and in order to sorta prove it, I plan to do the next few blocks with epoxy. If I get less distortion, then I'll continue with epoxy to glue up the blocks.

I know I departed a bit from your initial subject but the use of moisture containing wood glues in this application somewhat applies. I'm interested in your thoughts.

Thanks for posting.

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JJ
Napa, CA
http://www.DonohueGuitars.com

I use T-88 epoxy for my fret boards and wood binding/purflings and it works fantastic. You have great open time to clamp and clean up your squeeze out and the cured joint is very strong.
If you mess up somehow on the fret baord installation just place your heating blanket on the board and voila it comes up easy with a spatula.
The way I see people bang and knock their guitars around I feel the epoxy bindings are just the ticket as they will never pop off. I kept samples of my glued binding and top herringbone purfling and it took a framing hammer to crack them apart. (a very scientific method!!!)

Here's the info on the T-88. http://www.fiberglasssupply.com/pdf/epoxy/t88_tds.pdf

Ray

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Guitar Building = Continuous Improvement Process

I think Alex hit on a good point here. It may depend on your building sequence whether water based glues will introduce back bow or not. I think there would certainly be more chance of it if you are gluing fully carved thin necks to the fret board. Fretting after gluing can cause back bow also if the frets are a tight fit. There probably isn't much chance of back bow if you carve after you glue the fret board. I use LMI with no problems.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Another epoxy user here. I use West Systems. As has already been said, it does dry extremely hard, and is just as reversible as Titebond, and does not leave a thick glue line. It also does not introduce moisture into the joint, which frequently will cause backbow, whether you've seen it in one or two builds or not.

Also, I've found that gluing a fretboard onto a neck blank before it has been rough-thicknessed is not a great idea no matter what type of glue you use. Once you start taking off a bunch of material from the neck, there's a good chance it's going to move, and can actually move a lot. I've started safety planing the neck blank close to final thickness before attaching the FB. Just my 2 cents.

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

If you became allergic to epoxy then there really isn't much choice there unless you wear full hazmat suit anytime you work with epoxy.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Very true!

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

Like kena dn others, I glue my unradiused FB onto a large rectangular neck blank, using TB. I dont have any issues because I radius and flatten after the neck blank/FB is set to the body. Only then do I carve the neck itself.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

This is great, a lot of guys skinning cats well in a lot of different ways !
So open time, strength, reversibility, gap filling, lack of moisture. Good properties.
Some points I would make: First time or folks with not a lot of epoxy experience would be well advised to get familiar with epoxy before slathering it on a fret board. West Systems put out a pamphlet called I believe "The Epoxy Book" which is excellent to have and read before using expoies. Mixing can be critical and some things are counter intuitive. (Such as more hardener makes it harder when the opposite is the case)
When gluing with epoxy it would be wise to wet out both surfaces. ( As a aside this is a good practice with any glue. In fact this is a criticism I have with some videos I have seen or books where glue is heavily applied to one surface and the mess clamped together. If you completely wet out both surfaces you can use less glue, have less squeeze out, less slide of parts and more penetration of glue for a better joint. For some things this is not possible or practicable but in general it is the way to go. I think it would be very hard to do this with hide glue and braces for example. )
Back to the epoxy. It is a thicker glue and can be softer than dried PVA if mixed just a little off. So I see the good points but what do you guys think about the sound transfer part. Non issue ? Pause for thought ? Concern ?
Link

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Cut to size.....Beat to fit.....Paint to match.

Taylor carves their necks with the fretboard already attached, and they have the luxury of waiting as long as they like for things to reach equilibrium before they do. If you take enough time between steps, then any moisture-induced stresses will dissipate, but there are other glues available if you don't want to take the time (and they work just fine, so why not?)

Someone should really put up a memo about epoxy, because I see the same falsities posted about it over and over. You can get epoxies that cure flexible or as hard as anything, you can get epoxies that kick in two minutes or two days, and you can get epoxies that come in viscosities down to almost water thin right up to putties. You can make a thicker, thinner, softer, harder, faster, or slower glue line with epoxy than whatever you'd like to compare it to if you have the time and expertise. In the end, though, I'm firmly in the camp that 99% of the issues with various glues are more with users than the materials (though I do count not understanding the materials as a user error!).

Mario addressed the 'glue acoustics' issue very succinctly in that other forum: the 'magic' of hide glue is that it forces you to make good joints.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Link, I think you are right about the importance of a proper mix ratio (and good mixing) for epoxy. I often hear the complaint that epoxy is soft but I have never experienced it. All I can figure is that it's poor mixing. I always mix mine by weight because it can be so difficult to mix small amounts by volume.

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http://www.chassonguitars.com

I don't know if back bow is the problem but twist may be the factor to avoid water based glues.
Personally I decided not to use any glue that may introduce moisture into the neck, that goes for ALL areas of the neck.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

I've glued all of my fretboards (30+) on using either HHG or Fish glue except for the first 3 or 4 when I used TB or LMI white. not once have I had an issue with the neck warping or twisting. To me it's just not a problem I have ever encountered. Think for a minute about the volume of glue left in the joint when you have clamped it up, it's almost nothing, and the amount of liquid it can therefore transfer to the wood is infinitessimal, work it out. If you can transfer a lot of water to the wood then you are using too much glue too loose a fit.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I don't see the issue as how much water is left in the glue line after it's clamped up. A lot of water is quickly absorbed by the wood from the moment you start applying a water based glue to the surface. So, it's already in the wood by the time you get it clamped up.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Has anyone ever considered the use of a urea formaledhyde glue like Unibond 800 or a similar product? It is the pretty much the de facto standard for things like veneering and bent wood laminations in the furniture industry.

The desirable properties are very similar to epoxies. It exhibits zero creep. Dries extremely hard and rigid. Has gap filling ability. Very good resistance to both moisture and solvents. And has the added benefit of a very long open time (I believe in the neighborhood of 45 minutes).

Thanks for the education on this subject, neighbors, I've been wondering about this very subject for the past couple of days. Being a user of yellow glues such as Tightbond in my line of work, experience tells me it can cause warpage if too much of it is absorbed/pressed into the wood. All that moisture has to escape from the adheasive right into the wood, swelling the fibers and forcing movement. It really doesn't take a thick film of yellow to be effective. A thin film applied to both pieces would minimize moisture invasion, but you have to move quickly because yellow glue does set pretty fast, especially thinly applied. We use white glue if we need more adjustment time.

I think the problem with formaldehyde would be reversibility.

Cheers

Kim

Excellent point. I can't say I have any clue if urea formaldehyde adhesives are reversible or not.

I don't understand the water issue. If I can't get ink to penetrate super thin wood veneer (yet), they why is glue, which is thicker, going to "penetrate" the neckwood, and a hardwood like Ebony or oily rosewood?

Not saying it hasnt happened, but I wonder how this happens. Kind of a contradiction here.

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Here is what a Parlor Guitar is for!
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