Gluing Ebony to Goncalo Alves

[Michael Polutta]

I will be needing to glue an ebony fretboard to a Goncalo Alves neck blank in the near future. Would hide glue be a good choice? Folks on MIMF seem to be concerned about inducing backbow due to the water content of the glue. They tend to recommend epoxy for this joint.

Recommendations? My preference is hide glue for everything, but this will be my first neck so I am being extra cautious.

Thank you.

[Donald A. Fortune]

Hey Michael- I'm in the process of making a classical guitar with an ebony fret board and would be interested in seeing responces to your post.. from what I hear, ebony is an oily wood so it will need to be treated with something to tame the oil first and then hyde glue should work fine... (corrections requested)
peace,
Donald

[Greg Mirken]

Hide, si; epoxy, no!

[Bob Webster]

Well, I guess I'm going to be a bit contrarian in my response relative to Donald's and Greg's replies. No offense intended, please.

First off, I know that every repairman would love for builders to use nothing but hide glue for every assembly point, and I can't blame them. However, there are issues with using water based glues that epoxy solves very neatly. When a fingerboard gets glued to a neck blank, there is a tension created due to the gradient of water content in the two pieces, and water tends to dissipate through the ebony extremely slowly. Once the neck is shaped, those tensions can create bows on occasion. The fingerboard can even end up a bit cupped across the width. The other thing that happens is that the ebony is extremely slow to return to its pregluing width, so that a few months afterward one quite often sees protruding frets that have to be redressed. I finally switched to epoxy about 5 guitars ago and all those problems went away.

As for ebony being oily and difficult to glue, I have to say that I've not heard that before. I'm not aware of anyone doing any special treatment of ebony prior to gluing as one might with cocobolo, for example. When one brushes on a water based glue onto ebony, it does tend to "fish eye" a bit but I think that's just because it's so dense that the water just doesn't penetrate fast. Does that make sense? However, if in doubt, it never hurts to hit it with a bit of naphtha.

Cheers,
Bob

[Tim Mace]

I thought naphta was a trade agreement. I wipe mine w/acetone!

[Paul Hostetter]

If you have a double-acting trussrod, you can deal with backbow, which is a possibility. I don't have a problem with epoxy for such a task. It has a sonic transparency roughly identical to hide glue, if that's your concern.