Acoustic Guitar Construction

Good response Dave. I can't figure why titebond wouldn't hold. Maybe applied too thinly? Who knows?

Dave - for what it's worth, when I did some veneering early this year I used Titebond Cold Press Veneer glue. It worked quite well, although it had a different smell to it. Then again so does contact cement.

I can't say for sure that it would work for laminating several layers. It will be interesting to see what the company suggests in response to your question.

For what it might be worth:

Michael Collins recommends against using Titebond if you use vacuum to clamp the lams together. The reason is the vacuum system does not allow water to evaporate fast enough to effect a proper cure, thanks to the need to seal everything to maintain vacuum. Instead, he recommends using a glue, such as urea formaldehyde, that cures by chemical reaction. Epoxy would, of course, meet this threshold as well.

I conceptualize Titebond as a bunch of molecules of "contact cement" that are suspended in water so that they cannot make contact with each other. As the water leaves, they make contact and "bond". If the water can't escape, the molecules remain suspended. However, given the nature of wood, a certain amount of water would be absorbed, enabling some bonding to take place. Sounds like not enough to make a durable cure, but enough to provide the appearance that it did. Just about the most diabolical result I can imagine. But it is intrinsic to the nature of Titebond and not a manufacturing fault. For a vacuum press of any type to work, it must be almost perfectly sealed, right? There is nowhere for the water to exit.

If you use the "open" caul system and Titebond, Michael recommends that you leave it clamped way longer than normal, as in 24 hours or longer, as I remember it. This is because even though it is "open" it is not that open, and therefore requires a longer time for the water to escape.

Thanks Dave D. Sounds like Titebond makes a special formulation for jobs that will be encased by air tight bags.

John just a day or so ago I saw a thread where a top was being glued up inside a vacuum bag. Had blue painters tape to hold in place. If they were glued with Titebond are you saying there's a possibility for failure there? Hmm! I thought it a great method.

Yes -- we need to stop this assertion right here regardless of MC's opinion --- vacuum clamps have been used with Titebond original forever. I would say if it were true all those with Taylor and Martin guitars are in real trouble since they use Titebond for much of their construction with vacuum clamp processes. Plus in one of the factory Friday videos Bob Taylor mentions that the vacumm clamp improves the process by quickly drawing off moisture.

It will be interesting what Franklin has to say about Dave's situation -- my guess -- and it is only a guess is that it is simply a case of a starved glue joint, not enough glue to get the both surfaces "wet" which is needed to start the adhesion process with PVA.

I believe the "slow dry" and "cold press" Franklin forumlas have more water and being runny is one of the user complaints.

I don't know how safe it is for home use but urea-formaldehyde glue is used for commercial plywood manufacturing so it would seems to be a good choice.

Dave, I just got into the discussion, and I'm sorry for the set back on this build. We will all be interested in what Franklin has to tell you.
I can't imagine that the surface of the laminations was to smooth, as in sanded to too fine a grit and the glue could not grab, but any possiblity of this being the case? I know it's not your first time doing this so I hesitate to think of this.
Starved glue joint sounds possible too.

Just another opportunity to move onward and improve the process!

Kevin