Gluing blackwood

[David Payne]

I have had this set of black wood sides and back I have been saving for 5 years. I have worked on rather oily Brazilian and other rosewoods that glue fine with Titebond I.

However, The back bracing won't stay attached. It pops off like the black wood back as if it is Teflon.

What glue should I use?

Thanks,

Dave

[Dave Yelverton]

Dave, have you tried de-greasing with naptha? I usually do that as a precaution if I'm not sure of the wood, and to date, I haven't had a mishap. Have you tried the white glue from LMII? If you haven't read it, here's a link to an article by Tim McKnight, which seems to com down very positively in favour of it.

http://www.mcknightguitars.com/glue-vib.html

Regards

Dave Y

[David Payne]

Dave,

I had not thought of naptha but was about to attempt a similar idea with a little acetone.

The white glue from LMI is nice and I have used it, its just easier to pick up Titebond at the local hardware store. I should order some.

Thanks,

Dave

[Len Biglin]

Dave , is this Australian Blackwood? I have made 3 acoustics from it and never had a problem , used original titebond, and never de-greased it.Good luck.Len

[Russell Vance]

Len, we work with Australian black wood (Arcacia Melanoxyln) every other day - as you say titebond works just fine -
I supect this is Malaysian Blackwood or similar. Sand the back with some 220 and wipe with acetone which is better at removing extractives/oils and other things that interfere with the gluing process , open the wood up a bit with a wipe of clean water (pay attention to whether the water is readily absorbed or 'beads' on the surface). If it beads you have problems as the wood will reject Titebond to a greater or lesser extent. You can try using a toothing iron on the back and braces as a last resort but I suspect you have some nasty wood.
Also, some related info: be aware that some wood is thicknessed in machines that the operators have waxed the bottom platten to assist in the feed. This wax is forced deep into the grain of the wood by the feed rollers and will not take finish readily (fish eye and cratering) and while I don't think this is the case here, glue will not stick to wax. R.

[David Payne]

Russell,

The source of the wood has never given me problems with wax. This blackwood is one of the finest pieces of wood I have ever worked with in that it's color, grain and great sap wood (for a color stripe down the center back seam and head stock laminates) are beautiful.

I did the finish surfacing in a long horizontal drum feed sander because it had to be made thinner to bend etc. Also, the back plate seemed to need thinning (more than normal) to get the tap tones I am used to hearing for good results. Of course this is subjective.

The wood has been drying in my shop for years and was ordered from a luthier supplier so I am pretty sure it was ready. It has been amazingly stable with no new cracks forming over the years it has been sticker stacked in the shop. My understanding is all rosewoods are prone to crack for no apparent reason even after proper drying. I have noticed some luthiers will not warrant their rosewood (and sometimes stuff like zircote) guitars against cracks because of this tendency. I guess it is just really oily material by nature, worse that other rosewoods.

Thanks,

Dave

[Russell Vance]

Dave, oops, I wasn't questioning your preparation ...I was bringing into play the prep from the source you purchased it from and just saying all I knew in the hope that something may have been relevant. Hard to recommend a glue here.....even epoxy has trouble in that environment - our national science organisation over here did a lot of work with difficult to glue Australian hardwoods and came up with Urea Formaldehyde as a solution (we've used it but it is sensitive to temperature - dont use it cold) for oily wood gluing.

[David Payne]

Russell,

I didn't take it that way at all, I just had to do a lot of careful prep since the wood won't really plane....it tends to grab on the planer blades and get spit out in many little pieces. I had a bridge blank explode in the planer once so fortunately I learned my lesson before.

I was thinking back on when I joined the plates and added the back reinforcement the glue stuck because it was right after machining. However, I am going to sand and use the solvent from now on.

The Titebond is working well now when I use sanding/acetone but I will be constantly checking before I build further....

Thanks,

Dave

[David Payne]

Len,

It is African Blackwood (Rosewood, Dalbergia melanoxylon). Very black, yellowish sap line, very hard and brittle. You can't feel the oil on the surface but it turns a white rag black very quickly when wiped down with a strong solvent.

So far, the acetone route seems to make quick work of removing the oils. It kind of seems like an astringent effect in that the wood seems to stay looking dry for a while. I sanded the areas and wiped them down working one glue line at a time.

Thanks,

Dave