Official Luthiers Forum!

Kent, for me it really is about the sensitivity/health concerns, I've never seen the amine blush either. I have been experimenting with fretting after the board is glued, this does allow me the opportunity to flatten/work the board one last time before frets go on so maybe the other glues would work considering I'm doing it this way now.....I have had great results with the process I'm using so I hate to mess up a good thing, but for the sake of good health I might give water-based glue a shot again. By the way, your guitars are looking mighty spiffy these days, good work my friend!!

Greg

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Gwaltney Guitars

I use titebond. I apply just enough glue so that the surface glistens without being opaque, and clamp overnight. Never had a problem.

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Old growth, shmold growth!

That's interesting. I'll give that a try next time I use titebond on large surfaces. But I can't figure out why that would work. At 6 hours, the glue is pretty well set. Seems like if it needs to dry to flatten out, it would flatten whether clamped or not (and I know things like that don't flatten if unclamped, even after years!). Do you think the glue is creeping in those next 18 hours? Not arguing, I just don't understand it.

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http://www.chassonguitars.com

I believe when items are clamped between non-porous cauls, the glue dries, but there is still moisture trapped against the veneer. It takes it a long time to get out of therre. I have had situations where I had to keep it clamped 3 days for it to become stable, using strips of Melamine shelving as the cauls.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Perhaps too much glue in the joint initially,saturating the material on each side, even if you have good clamping and lots of squeezout?
Titebond only gains strength by drying out and that water has to go somewhere.

Amine blush has nothing whatsoever to do with sensitivity, they are two completely different issues.

Amine blush is a salt based oily excretion which forms on the surface of cured/curing epoxy. It is a direct result of amino acids reacting with H2O and CO2 in the atmosphere. It has a direct effect on the ability of many finishes to adhere to, or harden upon an effected epoxy surface that has not been thoroughly washed to remove the amine residue. Amine blush can affect the fingerboard joint by forming a 'raised edge' in the finish which follows the epoxy glue line perfectly. This raised edge can be sanded flat, but the finish will continue to rise forming the same problem again and again.

Epoxy sensitivity does not require the stuff to be on the suffers hands for extended periods, nor does it require one to have breathed in the vapors for weeks or month, that is misleading misinformation and is not supported by my own medical history or that of many others who have been directly affected. Basic precautions do reduce the risk of epoxy to a lower level, but some users develop issues very quickly and its a luck of the draw situation.

On top of the obvious basic precautions that have been mentioned, good advice is to keep a fan running on you and the work piece at all times during mix and application to keep fresh air blowing the CO2 and H2O from your breath off the work piece. More importantly it will push most of the toxic fumes away from the user. Alternatively, work outside in a breeze. This simple step will help reduce the possibility of amine blush forming and go a long way toward avoiding the sensitivity issues.

It is also worth noting that there are 'low blush' formulations of epoxy on the market, however these products tend to have a low MOE so are not very useful if you need a product that will sand easy. Those products that cure to a more crystalline state are better for our use, but because of the raw amino hardeners used in their production, they are also the most likely to cause a sensitivity issue for the user.

Cheers

Kim

That's not necessarily true Kent.

I always glue a maple veneer under all my fretboards. I do this prior to glueing the fretboard to the neck. I use Titebond for that. Once, for a reason I can't remember, I had to chisel off the maple veneer to reglue another one. To my surprise, 2 hours after the clamps wrere on, there was an area in the center of the fingerboard (about 1"x4") were the glue was still fresh.

So if this can happen with a thin maple veneer, imagine for a glue surface stuck between a fingerboard and a neck...

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Thanks. Good to know.

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http://www.chassonguitars.com

Low blush does not mean no blush. With the epoxy formulations used in luthery there will always be blush that needs to be removed. It may not be a thick, readily visible waxy layer; but it will be there unless removed (and sanding is not an effective way to remove it).

Epoxies will not cure to a crystalline state, they form long chain polymers in a glassy state. When heated above their glass transition temperature (Tg) the MOE drops significantly as they transform to a plastic state. Epoxied fretboards can easily be removed by heating the glue line above the Tg and then shearing the fretboard off the neck.

If an epoxied fretboard is removed and then replaced, it must be reglued with epoxy or the bonding surfaces must be scraped back to bare wood.

Please don't underestimate the risks associated with working with epoxy.

-jd

No, Todd. I've made that point and it seems to me that true believers of all sorts (I include myself in this instance) are immune to further discussion. However, I am forced to agree with Al Carruth that gingerbread too is better without epoxy. Al's always ahead of the curve!

Rick