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I’m not new to guitar building, but I need some help with what kind of epoxy is best suited for gluing oily woods like members of the rosewood family. I’m working on 10 necks at the moment and on two of them the fingerboards came off. I used hardware store brand epoxy, mixed it as best I could – trying to get equal amounts of both components and blending thoroughly. I also used 25 grit sandpaper to roughen up both surfaces in a criss-cross configuration, and I wiped the surfaces down with acetone just before gluing to remove the oil. Then I clamped the surfaces together and left them for about 24 hours. The two that separated looked as though I forgot to do the sanding with the rough paper. One was ebony, the other was Cocobolo – both glued onto birds-eye maple. I can re-glue these after scraping off the old glue, but I’m concerned about the ones that didn’t separate. I have no way of knowing just how well these are bonded since two of them didn’t seem to be bonded at all.

Can someone suggest a brand of epoxy that works exceptionally well for what I’m doing? Is there something that I should be doing differently? Should I be using a different adhesive?

Sincerely awaiting your sage advice!
Wolf

West System...Smith Epoxy...System 3

Some say that the acetone wash is self-defeating and that it only induces more oil to rise to the surface. Also...could you have over-clamped and starved the joint?

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

I'd guess your problem is the epoxy. We used to glue acres of teak to teak with never a failure, with WEST System and SYSTEM 3, and I'll bet folks will weigh in with their favorite, and none of them will have come from Mall-Wart.

Measure as accurately as you can, but don't obsess.

Stir thoroughly, until you think it's well-mixed, and then stir for another 60 seconds.

Paint a thin layer on both sides of the joint, and while that soaks in, mix some thickener (NOT sawdust) into the remainder, to a just-barely- liquid state, but not to mayonnaise.

Spread a THIN coat of this on one side.

Clamp lightly - DON'T try for maximum squeeze-out, this stuff holds best with a little in the joint.

Scrape off the squeeze, and keep checking for more to scrape off. Epoxy filled with some thickeners, like silica, can be brutal to sand.

Dan

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Dan
http://www.acme-archtops.com

Wolf here is a link to epoxies that I use and have had great results with them. I do use them in a non guitar product, but something that takes a lot more beating than a guitar.

Mike

http://www.shopmaninc.com/epoxy.html

I am going to play the devils advicate here. I have glued up a lot of rosewood over the years. Coco can be a bear if not treated properly but I have found most rosewoods are not that big of an issue at all with PVA or HHG. I wipe the joint area with Naptha on easy rosewoods like Hond. and IRW and acetone on difficult rosewoods just before glueing and have had not trouble. IRW is a sinch as are most others rosewoods

Now to your issue with epoxy. I too have a sneaking Idea that you may have over clamped the joint.

Wolf--

You might give the Smith's All Wood Epoxy a shot.

http://www.lmii.com/CartTwo/thirdproducts.asp?CategoryName=Adhesives&NameProdHeader=Smith+All+Wood+Epoxy

Ditto on the clamping. For small quantities, measure with a scale and stir well. I did a stitch and glue mahogany kayak and used System III. I made anywhere from 2 to 4 oz per batch and stirred 100 revs with a Popsicle stick.

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Jim Howell
Charlotte, NC

I never - ever - use hardware store epoxy as an adhesive.

Lots of good epoxy suggestions above, just make sure you get epoxy "adhesive" and not finishing resin or something else.

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The member formerly known as erikbojerik....

Sounds like some sort of cure problem or maybe a clamping problem. You're better off using more hardener than resin if you're going to make an error as at least you'll be sure it all solidifies. If the clamps loosened in mid-job and your parts didn't fit properly then you could have had the parts pull apart. The competing view on gluing rosewoods is that a freshly planed joint is the most effective pre-gluing treatment and the jury's out on whether solvent wipes help or hinder. That doesn't explain anything about the ebony failure, though, so it's gotta be a problem with the glue, the joint, or the clamping. If you're sure the joint was good and the clamps were tight then it's likely a bad batch of glue.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

scrape the sides of the cup...

Unfortunately, too much catalyst can saturate some compounds making it so they never set, so proper ratiometric mixing is very important. Also, where I work, we make it a point not to use all of what we mixed - partly to ensure that the rest sets, secondly, because using all of it means you are scraping the edges that may not have been mixed well - meaning you might be trying to glue something with just a resin film...

Stephen

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www.ziegenfussguitars.com