Official Luthiers Forum!

When it comes to hardware store-grade epoxy, your friend would be right. Hardware store epoxy that doesn't fully cure happens because the polymer chains never fully cross-link.

Aerospace-grade epoxy is another matter entirely. My personal preference is Hysol EA 0151. I've settled on that formulation for a few reasons.

First, it's optically clear. It also cures to a rock-hard state because the polymer chains do fully cross-link. This makes it a good transmitter of vibration.

One of the characteristics of epoxy is Tg, or glass-transition temperature. It's the temperature at which epoxy goes from a solid state into a softer, rubbery state.

Some epoxies have a Tg over 250° F, which makes them unsuitable for luthery. 0151 has a Tg of 136° F which puts it in the removal temperature range of HG.

Once heated, epoxy can be removed from the surface with a putty knife leaving no residue behind.

So thanks for the details guys and we know as I have offered early on that there are quality epoxies out there that may pass the sonic vibration transmission smell test.

So as you all should know when you say "epoxy" on this forum someone, someone is likely to pick-up the 5 minute variety in two applicators from the check-out line at Lowes and go at it in their shops.

I'm very careful and you can search my posts all the thousands of them when I refer to Titebond Original I always refer to Titebond Original. With this said if you are promoting the use of epoxy please be sure to say what brand, type, etc and be specific so that what people come here to learn does not end up harming them in some way if they misunderstood you.

Now here is where I disagree with all of you who are promoting epoxy for a fret board. Again I concede that a quality epoxy such as West, what I used or SIII and some others are suitable when it comes to transmitting vibration for a fret board. But I am not convinced that it's as good vibrationally as HHG or Titebond and I would bet that it isn't.....

Would you use the same epoxy for your bridges? And if you would or would not why would you or would you not use epoxy for a bridge? In the repair world epoxy is ONLy used for bridges when it's suitable for the instrument meaning the instrument is on its last leg or never was all that such as an Ov*tion.

So the bridge terminates the speaking length of the vibrating string via the saddle. On the fretboard side the other end of the speaking length is terminated by the nut for open strings and the frets for a fretted note. That fret is attached to the fretboard glued onto the neck in your cases with epoxy.

If you are terminating the speaking length on the fretboard end when the board is attached with epoxy I ask again why do we not trust epoxy for bridge attachment?

Some of the reasons are that again to many the word epoxy does not mean an aerospace grade epoxy cleared for NASA life support missions. It means the crap in the checkout line at the grocery store....

Glue lines are a topic that we could get lost in all day but I'll avoid that here. One comment though when I build a guitar I want to hear the wood not the glue, not the finish, etc. So a thicker glue line is not desirable to me.

lastly and the real biggie what about serviceability down the line.

It's rather laughable or at least it was in our shop earlier this week when the contention that epoxy is easier to use was shared with other working in the trade luthiers.

It's not easier to use and from the get go you have two parts to mix that you can and people here on the OLf have gotten wrong in the past. This adds complexity and one of the reason why Titebond Original was invented and other glues like it and why they are favored to produce the millions of guitars that are produced every year is it's ease of use.

So 12 years down the line I have a guitar on my bench with a bridge lifting that was glued on with epoxy or I need to remove the fret board that was also glued on with epoxy. Ov*tion day, oh the horror....

If I reglue the bridge after struggling with patch clearing dulling the hell out of my chisels on epoxy residue if I use epoxy once more how to I clean it up on the red, bursted finish on the top and the black finish on the neck? If I use solvents that will dissolve epoxy I eat and destroy finish and now I have to refinish the instrument because epoxy glue is less serviceable than Titebond Original.

I will go so far as to say that the very bad reputation that Ovation Guitars received for being unserviceable has as much to do with the use of epoxy throughout the assembly as anything else....

The ability to release with heat is only one part of what makes a glue serviceable where the other parts come into play when and if the instrument needs servicing in the future. Easy, non dangerous to anything clean-up is also a bit part of being serviceable.

So use what you want. I went with epoxy too but returned to Titebond Original and as others have said here simply using a strong back for 48 hours or some methodology of your own to counter any warpage from water in the glue and this need not be an issue nor has it been for the tens of millions of guitars built with water based glues.

And lastly from me. I still think that even a quality epoxy is not as vibrationally transparent as HHG (the gold standard) or Titebond Original and I'll add Extend too since someone else brought it up, good stuff.

And really, really lastly from me for now... when Ovation entered the musical instrument business they were a helicopter company who had lost contracts because of the end of the Vietnam war. The employees were asked for ideas of other lines of work the company could do to avoid layoffs. The guitarists in the company chimed in and thought that an aluminum neck that would never warp would be a great value proposition for Ovation to build guitars.

The company had a great deal of experience with those aerospace grade epoxies that Dan is discussing and one of the reasons why they were experienced with epoxies is that in the aerospace world, my former world vibration is the enemy and not your friend. Nearly all that you do when designing airframes has to consider at some point the impact of vibration on the surfaces and airframe.

Epoxy is dampening and typically has thicker glue lines too meaning you are riding on more of it and I again want to hear the wood and strings not glue.

All day long I deal with loyal Martin customers who find HHG a real selling point as well. Tradition in the acoustic guitar world is very strong, you might say it's the "force" of the vintage guitar market. I see using epoxy as something that others, customers might object and even more so in the "high-end" guitar market and I would side with them as well and I think it's unsuitable for fretboards, not necessary, harder to use and less serviceable in the future.

Thanks.