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I am using an epoxy for a fretboard glue-up and noticed that after about 24 hours the squeeze out was still a little tacky. Is that a sign that this stuff is not going to set properly?
I normally use Titebond but because of a carbon fiber fretboard extension I was going to use epoxy.
Should I give it another day to see if sets or pull it off and try again?


T

What is the cure time on the epoxy?

24 hrs.

Waiting won't hurt anything but if it's still tacky after another 24 hours at reasonable room temperature chances are it didn't get mixed properly...or it was measured inaccurately.

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StuMusic

Well, I let it sit another day and there were still tacky spots in the squeeze out. So I gave the fretboard a little tug and off it came!
It appears that most of the epoxy had cured but it did not adhere to the ebony fretboard. There was a hard coating on the cherry neck but not the ebony.
Any recommendations for an epoxy that will adhere to ebony?

Thanks,

T

Did you clean the surface of the ebony? Ebony can be very waxy and resistant to glue. Some people like to use acetone to clean the surface and others just scrape and scuff a fresh surface. Proper clamping could be an issue too, When the board popped off did it leave behind a cast imprint of epoxy? Was there any epoxy on the ebony board?

I've seen longish term (4-5 months) adhesion problems using West Systems epoxy on ebony. It was used to put a bridge on a sound hole-less ovation, so adequate clamping was tough. The bridge just came off, with the bottom of the bridge looking completely clean. Sounds like you've got something else going on though. Were you using hardware store epoxy? I think home depot, aubuchon, etc. sell that cheap stuff in the two tubes (loctite?) with names like, "2 ton", "crystal clear", and "Heavy Duty", etc....Ive never been able to get this stuff to set up right. It always stays tacky.

I've had good luck with the hardware store epoxy, once or twice anyway. It does have to be fresh, properly proportioned, and throughly mixed to give you about a 30% chance of sucess. I wouldn't consider using it on a guitar...

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The fretboard was freshly scraped prior to gluing. I was using some hobby store epoxy with a 30 min set time and 24 hour cure. I have used this stuff for other projects without fail.
I had good clamping and yes, it did leave a perfect impression in the epoxy on the neck blank. The fretboard came off perfectly clean with no epoxy residue whatsoever. I have done a couple of tests since then and have successfully glued EIR to Cherry with no problems and Maple to Walnut with no problems.
I have been doing some digging on this subject and have found that Ebony can be a problem to glue with epoxy. I may try the Smith's epoxy that LMI carries to see if it works. I just hate to spend $25 on the stuff since I probably will never use it up before it expires! If it wasn't for the carbon fiber insert I would just use Titebond as usual. Perhaps I will go back to my old method.

Thanks for the input!

Rough up the ebony with very coarse sandpaper.

I would think there is still plenty of wood to wood contact to use Titebond around the carbon insert. I'm not a big fan of epoxy because I've seen it behave in the same manor you describe plus it's toxic and kind of nasty.

I have considered that. Here is a pic of what what I am doing. I need the FB extension attached to FB so it can pull it down flush with the top.
I have been using 3/8 Finnish plywood for these but wanted to try the carbon fiber plate because of its rigidity and it is only 1/4 thick. Not sure I am going to gain much but wanted to try something different.

It's possible to squeeze out epoxy to the point that it won't adhere. You may have had too much clamping pressure.

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A big issue I have seen with epoxy use is over clamping which can starve the joint of glue which can cause adhesion issues. With titebond and typical wood glues this is hardly an issue but with epoxy it can be.

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Did you apply the epoxy to both surfaces before closing the joint?

A friend has recommened T-88 from System 3. He said he has used for Ebony without any problems.
And yes, I did apply to both surfaces.
From what I am gathering from around the web Ebony has a problem with epoxy adhesion. There are other oily woods that pop up in searches as well but Ebony appears to be one of the biggest culprits. Wiping it down with acetone seems to be a popular practice as well.

We will see...

Smiths all wood epoxy soaks into ebony, like draft beer into a frat house carpet. I have used it with excellent results on at least 50 fingerboards. Well worth the cost, it has a good shelf life if you store the two parts separately. I like the slow cure time, it gives you lots of time to work.

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A local friend has some of the T-88 so I thought I would try that first.

Freshly sand both surfaces with 80 grit sandpaper and use only moderate clamping pressure. I don't find any need to wipe with acetone.

In case anyone is interested, the T-88 work perfectly.

T