Official Luthiers Forum!

I came across this article. (It's short)

http://www.treesearch.fs.fed.us/pubs/24715

I didn't undersand all of it, but thought it might interest some of you. It's about gluing wood with epoxy and testing the strength of the joints. They say that epoxy does not make excellent bonds for wood. They test it with heat and water and steam - exterior conditions, so it may not be relevant to guitars. And I guess we don't want permanent joints do we.

Happy new year!

Mike

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Mike Lindstrom

Mike not capping on you but that article said a whole lot of nothing about epoxy and wood.
What kind of epoxy, what kind of wood, how was the wood prepared, how was it clamped, etc. What conditions, etc.
Did I miss the rest of the article or was that it ?
The Gougeon Brothers research and 30+ years of building high performace sailboats out of wood and epoxy seem to prove that when used the right way epoxy bonds prettty well to wood. They have done extensive research on this. I would have to see more than a statement that says, it doesn't and it is not understood why, to believe other wise. It may be that when used the same way as traditional glues it doesn't bond well. Just as with hide glue there are things that need to be done to get the best out of it and people who use it as with any glue would be well served to understand how to get the best out of it and it's limitations. I am concerned that someone could infer from this that epoxy is not good for exterior uses or other uses. So my point is one little article that says nothing vs. the reams of information from the Gougeon Brothers.
Link

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

I'd have to agee that epoxy sometimes gets a bad reputation because it was improperly used. Either mixed or applied poorly.

I've got a stripper canoe that I built 25 years ago that was built under less than ideal conditions and has seen tons of serious abuse. I had to repair a few spots but overall, the epoxy bonded to the wood well enough to be stressed and flexed and slammed into waves (and yes, a few rocks) and still hold up fine.

I've also got a bent laminated garden trellis that has stood up unfinished to the Pacific Northwest weather for almost ten years with no sign of problems.

Then there's all the cold molded sailboats and airplanes. I can't imagine what they are referring to.

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http://www.chassonguitars.com

You missed the article. You need to download a pdf. It isn't long, but it does specify wood and epoxy types.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Ill ask this again:
What about the LMI epoxy for wood/lutheri? Smiths? It is specially made, anyone use it over West systems?

http://www.lmii.com/CartTwo/thirdproduc ... Wood+Epoxy

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Sorry for the confusion Link. The URL I posted was to an abstract. As Howard said, there's a link to the pdf ("view and print.."). I didn't want to post a link that automatically downloaded some mystery file. The long version is only 3 pages so it's not really all that detailed either. He compared amine cured and polyamide cured epoxies (no I don't know what kind is used on guitars) on both flat sawn and quarter sawn wood. Put the samples in a stressful environment and then did some tests.

As I said, some of it's beyond me. I don't know know whether he's saying epoxy's not good for gluing wood, or if he's just saying it's not as good for gluing wood as it is for gluing other materials. And I hope that my guitars will avoid the environments he puts his test samples through.

Mike

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Mike Lindstrom

Thanks Howard,
I didn't click that part because it looked like a repeat of what I just read.

I read the article and I saw a few things that seemed contradictory. Also those tests seemed like torture tests. I am not doubting what they saw but I am thinking it is more of a thing of when epoxy fails it fails like this, but in "normal" conditions it works fine.
I have a rowing pram I made over 20 years ago of regular Lauan plywood, epoxy resin and fiberglass cloth. It has seen freezing conditions, temps of over 120° (it's black and on top of my truck in the summer !) flown of my friends truck at 60 mph, dragged over gravel bars, all the while being exposed to water, in the water, in the rain, well you get the picture. Sure I have patched it, (with epoxy) but it is still going strong. I have anchor releases I have made by laminating Mahogany to make a block that have been together in very harsh conditions for years.
As Kent has stated with his experiences it has worked well in outdoor conditions. I would not be the least worried about either it's strength or it's durablity especially for guitars, unless you are going to boil, bake, freeze, steam, your guitar.

Frei, I have not used Smith's but it looks fine and wouldn't hesitate to use it. The LMI I am sure is up to the task. If it were me I would use a 2 to 1 or higher ratio mixture epoxy such as the West systems. I like to use a low viscosity epoxy for the better penetration and control my viscosity myself with additives. That said if the LMI is all I had I would use it with out a bit of worry. Wet out both surfaces and don't over clamp ! A fret board has what, about 36 sq. inches of glue surface. (Ok minus truss rod slot)
Yeah, I don't think you would have any problems with any epoxy.
Link

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