Oily wood glues

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Greg Martin
Posts: 308
Joined: Thu Feb 23, 2012 7:18 pm

Oily wood glues

Post by Greg Martin »

This time around im using cocobolo and also goncalo alves, both very oily,wondering which glwues are recemended i have T88 epoxy,but also wondering about titbond III?

Aaron Helt
Posts: 79
Joined: Thu May 10, 2012 9:19 am

Re: Oily wood glues

Post by Aaron Helt »

I have always used Smith epoxy, from LMI. I only use it on the back join. Braces, rest titebond.

Chuck Tweedy
Posts: 1180
Joined: Fri Jan 06, 2012 6:25 pm
Location: San Diego, CA

Re: Oily wood glues

Post by Chuck Tweedy »

I guess I'll take this one.

Greg, "oily" woods like cocobolo are very successfully bonded with normal wood glues such as Titebond and hot-hide glue.
The key to success is to join freshly cut surfaces. The glue sticks to the cellulose fibers, so you need to expose clean, fresh fibers to give the glue something to hold onto.
Note that I said "cut surface" not sanded. Sanding can work, but it can also leave a jumbled surface of fibers and resin that is not as good as a cut surface.
So do this: Just prior to glueup, scrape the joining surfaces with a sharp scraper. Have a fresh, hot hook on that scraper so it pulls up whisper-thin shavings, and you will be good to go.

DO NOT wipe the surfaces with solvent - that is an unfortunate myth that has been widely propagated.
Wiping with solvent dissolves the resins between the fibers and paints the entire surface with rosewood juice (see my tag-line). Water based glues will not stick well to this well. I guess some epoxy's do - tho, IIRC, epoxy functions mainly through mechanical bonding than chemical (like wood glue), so I'm not sure what's going on there.
Likes to drink Rosewood Juice

Alan Carruth
Posts: 1033
Joined: Sun Jan 15, 2012 1:11 pm

Re: Oily wood glues

Post by Alan Carruth »

What Chuck said.

The key concept here is 'surface energy', which sounds 'New Age' but is actually a real and measurable property. Basically, when you remove material from the surface you're breaking chemical bonds, which require some time to pick up whatever they need from the air to fill the vacancies. If you apply glue during that time (about 15 minutes) it sticks better. The Forest Product Lab found this out back in WW II. Freshly planed surfaces are best; prep with a sharp scraper is almost as good. Sanding leaves a rough surface and a lot of dust that gets in the way.

Bob Howell
Posts: 224
Joined: Sun Jan 08, 2012 4:23 am
Location: Atlanta, GA

Re: Oily wood glues

Post by Bob Howell »

I have used CA glue a lot when epox is not handy. Heard it works fine. Tell me its true!! Fresh planned wood is often hard to provide.

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