Official Luthiers Forum!

No doubt there are some uses for epoxy in building guitars like the fingerboard but what about braces. Does anyone here use it for gluing braces to oily rosewood and if so which one? What would be the consequence of doing so: creep, weight, vibration, longevity, etc? Is acetone wash better than fresh sanding?

I find NO use for epoxy in building guitars and only limited use for it in making repairs.....

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Not advocating any of these things or not advocating them, just conveying information.

Ep*xy uses that I know about in Lutherie:

1) Fret board to neck
2) Pore filling
3) Braces on cocoa backs
4) Black ep*xy as filler for inlay
5) Seemingly everything on an Ov*tion.....
6) As finish under pick guards for Martin warranty work
7) As a crack fill (yep....) on tops with cracks that won't close and have been left open for a long time
8) To laminate CF to braces

Epoxy for bracing is just overkill I think. Sure you can use it but why bother when there are so many easier alternatives. No mixing needed with Titebond, easy clean up, 30 minutes clamp time and you are done.

I use Smiths epoxy to join white oak backs. I have my reasons.

I use epoxy for the "X" brace intersection --- no cap or cloth patch. BTW most epoxy releases with fairly low heat.

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

Gluing in Martin type truss rods. Laminating veneer lay-ups where glues with moisture may cause warping.
Tom

_________________
A person who has never made a mistake has never made anything!!!

In the past, I have gone the purists route and used hot hide glue wherever possible, but my last guitar was made almost completely with epoxy including (gasp) the braces. This is a falcate braced guitar with carbon fiber under the braces so epoxy was part of the process.

So yes, epoxy can be used in a lot of building aspects, and don't forget finishing (pore filler).

I thought falcate bracing had the layers sandwiched between wood so the fiber wouldnt need to be glued to the back. Im asking cause I dont know.

With falcate braces the CF is over and under the brace. This puts the CF tow as far apart as possible giving the most bang for the mass. So structural epoxy is needed as the joint needs a bit of filling.

_________________
http://www.Harvestmoonguitars.com

The best sounding and playing guitars I've made to date have CF soundboards. Needless to say, I use a lot of epoxy in guitar building. Doesn't mean I like the stuff. Not sure why you would want to use it for wood to wood glue ups.

Well I read this forum to learn but more specifically I am talking to a guy, very well known with a lot of guitars to his credit, about building a guitar with a Honduras back. He said he always wipes with acetone and uses epoxy with any rosewood cause its so oily. Id never heard of anyone needing to do that. I was wanting to get expert advice before I plunk down dollars. So you guys know and I dont, that is why I post so little.
I am under the assumption that the glue one uses is one of the small contributions to the sound. Thats what the whole Titebond/HHG controversy is about. Ive used a lot of Titebond in cabinet building and Im convinced from that, it may not apply, that Titebond is efficient but not a good idea for sound. I mean really it is liquid rubber. So youre putting a gasket between the brace and the back. Following that assumption epoxy is liquid plastic so it doesnt seem to me to be a good idea. Then again the glue used on back braces may not make any difference. They are just there to hold the back.

You'll find some guys swear by rubbing down oily wood with epoxy before gluing it. Others say it brings more oils to the surface. Some find a freshly cut or scraped surface takes glue just fine. Some just use TB and glue it up.

I've done them all and not had a problem yet. My prefered method currently is to take the surface off with a light scraper or some sandpaper just before gluing.

And you're right about the glue. Hot hide glue and fish glue both dry very brittle. People like it for that reason and because it is more easily dealt with in repairs. But a lot of great guitars have been built with TB.

_________________
Mike Lindstrom

Since 1969 for EIR --- surface joint, add glue (Titebond), clamp -- done. Not to say that there are other woods that need a different approach.

As a side bar major factories including Martin use Franklin Assembly 65 PVA for virtually all construction except of course for the way over priced models advertise to have been built with HHG. I am not exactly sure why but this product is sold in minimums of five gallon pails -- KMG is currently doing a feasibility to offer smaller re-packaged containers. I believe that its available with florescent tint.

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

I'm not sure that thinking about the mating of two surfaces with glue as a 'gasket' is the right way to think about it. There are chemical bonds between the two surfaces that cause them to bind and hold together. Besides if you put a drop of TB on a piece of wood and smash it with a hammer the next day you will see that it shatters and is quite brittle.

The gasket analogy is -- well we'll just say wrong. Take two freshly surfaced pieces of wood, spritz them with plain water, push them together --- try and pull them apart without sliding, its not a gasket keeping them from separating.

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

For braces I like freshly scraped surfaces glued with hide glue. Braces sometimes pop loose when the instrument takes a hit, and hide glued joints are one of the easiest surfaces to repair.
I have worked with epoxy a fair amount but I wouldn't use it for gluing braces.

We don't believe there is a consistent, audible difference in tone between so-called 'plastic' glues like epoxy, Titebond, or LMI Yellow and animal protein glues like fish or hide. There are major differences in repairability, cold creep (Titebond or other AR/PVA), and cleanup, but not in acoustics.

Titebond rubbery? May be that your glue lines are very, very thick, and the glue is 'lacing' due to surface tension effects. You might try to fit the joints such that the glue line ends up at under 1.5 mil - the glue should dry much harder then.

_________________
A constellation only takes shape when one maps the whole.
- Beth Brower

Rubbery Original Titebond PVA joints if there were such a thing when properly applied (never seen it in over fifty years now) -- I believe could be operator error or product degradation.

Food for thought -- John Greven

http://www.grevenguitars.com/pdfs/MartinMyths.pdf

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

I appreciate all the help you guys have given me. I now know that epoxy is unnecessary. I still dont know if its harmful. Does TB and HHG better use the energy that is available. Im not going to be able to talk this builder out of the epoxy without proof. I have the witness of several of you that you can glue RW without epoxy. I need to present why using epoxy is not as efficient as TB or HHG or ? I maintain that whatever glue you use will work but every one leaves a layer between the brace and the back. So a glue that behaves more like wood seems to be the ideal.

Just nail it together then, wood on wood contact, best tone

The only problem that I can see with that is the weight of the nails

John,

If you don't like how this builder proposes to build your guitar, get another builder. The relationship is already strained, cut it off now. This guy may be a fine builder and get excellent results doing things his way. If you don't like it don't give him your hard earned $$. If you came to my shop and wanted me to build an instrument with a different adhesive than I was comfortable with, I'd show you the door.

Steve

Not necessary, but not necessarily bad to have on hand, either. I've been pretty thankful for my bottle of Smith's All Wood Epoxy from LMI a few times this past year.

Food for thought - a builder (or repair person) with lots of guitars under their belt does not guarantee that they know their arse from a hole in the ground.... Lutherie is fraught with snake oil and rasta impostors with countless notions that remain controversial with the jury out....

Lutherie more so in the past than currently suffers from the idea that some breath their own air a bit too much and even though available, usually... some folks just don't get out much and exchange notes with others....

If you are looking for someone to tell you definitively what glue "sounds" better you will have no shortage of takers but a complete absence of anyone who really knows for sure. Ain't life great.....

peace!

"Certified Official" Glue sonic effect evaluator

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/