I received this question in episode 6 of the Ask Brian Boggs Show:
What’s your take on the new generation of CA glues? I think the first company was called Nexabond, but somebody’s bought them out. Any experience or thought on where these types of glues are appropriate?
I think it was in 2013 they had a booth at the Fine Woodworkings Conference, and I believe it was their annual educational conference and promotional conference. Anyway, I spent quite a bit of time at the Nexabond booth talking to the guys and peppering them with questions and trying to understand what problem they were trying to address with their product. And this is what I do whenever I am interested in looking at a machine at a show or whatever products … I want to know, what are you trying to fix? What’s broken in the woodworking world that you’re trying to fix? And after asking the same question about five times in different ways, I finally got one of the guys to say that Nexabond was not generated as a glue to solve a problem. Nexabond was a glue that was developed in trying to solve the problem of a completely different industry, and it turns out it also worked well in woodworking. And that’s totally fine, there’s nothing wrong with that, but I don’t know that it does anything radically different than CA glue, but CA glue that we know as, for example, Insta-Bond, or other superglues that we use in the shop.
One of the things that intrigued me about my conversation with them is that they were targeting this adhesive’s reaction to the salts and proteins in wood and that there was a chemical bond going on there that was unique to Nexabond. And they had some samples there of two pieces of wood having been bonded together with Nexabond, and I didn’t even bother taking those home to test them because, one, I just assumed that they were gonna be good bonds, and we have a lot of adhesives already who can readily generate a bond that is stronger than the wood’s bond to itself. So I wasn’t worried about whether or not it was possible to get a strong bond with Nexabond. I was more curious about whether or not Nexabond had a place in what I was doing, and where might it have advantages over other glues.
Their pitch is that it’s a very fast bond- it’s a superglue, it’s a nearly instant glue and that has as many problems as it has advantages. The problem is that you’ve gotta be very quick about your assembly process. But one of the problems that I’ve found is that you have to be really careful to have a very thin layer of this material between the two surfaces, and I was having trouble getting a thin enough layer. And so I was testing this in joints that I was already having great success with PVA glues, and just replacing that process or that material with Nexabond, and trying to get it to spread thinly like they asked me to. And I was getting a much higher failure rate than I was getting with the PVA glues.
What was interesting, though, is that end-grain bond, where the shoulder of a mortise and tenon joint butted up against the female part of the joint. That end-grain bond was amazingly strong, in fact it was hands-down the best consistent end-grain bond I’ve ever seen. So where you’re wanting end-grain bond strength, I don’t know if there’s a better adhesive anywhere. Even epoxy struggles with end-grain bonding unless you allow it to soak in really well. Now, other adhesives can glue end-grain. Hide glue can do it, PVAs can do it, epoxies can do it, but Nexabond does it very easily and very quickly, and amazingly strongly. But overall, I think that it doesn’t really solve a problem that I have ever had in woodworking.
There are several glues that we choose from- hide, PVA and epoxy- and those have a range of not only setting times, but they have a range of tolerable temperatures in which they can perform. They also have a range in the types of woods that they bond. Epoxy that we use- oak and teak are all wood epoxy that we use- bonds oily woods better than PVA glue or hide glue will. But Nexabond is … I think it’s pitched as really just a fast glue, and I don’t think the speed of assembly time is a problem in even small professional shops. Possibly in factories, but I think the cost of Nexabond is prohibitive there. So I just don’t see a future … I took home maybe four different samples of the glue, different thicknesses, and I ended up having a fair bit of it, but I never used it in any furniture because I did not trust that I would get a good bond. And I chose those words carefully. I did not trust that I would get a good bond, not that Nexabond could not bond well.
With all of the adhesives that we use in woodworking, where there’s a white PVA, yellow PVA (I mean I can list the whole gamut there) all of them are capable of generating a bond that is stronger than the wood’s bond to itself if applied correctly and used in a way that that particular chemical or adhesive is able to do its job. And that’s where the rub is. I did not mean that pun, but the way that each of those adhesives work, including Nexabond, is very specific to its formula. So, for example, in PVA glue you need to have at least 55 degrees in the room, your wood can’t be too cold, and you have to have an accurate surface contact and a reasonable amount of clamp pressure in order for that glue to give you the strongest bond it can give you.
Now, there are degrees below its strongest bond that are still stronger than the wood itself, so you don’t have to get perfection in order to have a PVA or any of the other glues to give you a good enough bond for most applications. So I think if you’re having glue failures and you want to solve those failures with a different glue, I would try to direct your attention away from the glue and toward your craftsmanship. Because whenever we have had a scenario where a glue bond has failed, I have always been able to track it back to something in the craftsmanship that failed, whether it was clamping or temperature, or all of the different things that attribute to a glue’s ability to achieve a good bond.
So adding a new glue that you’re not used to doesn’t necessarily mean that you’re going to have a greater degree of success or greater speed or greater production. In fact, I suggest that it’s a greater likelihood that improving your gluing techniques, your process and the precision of your machining, is gonna have a lot more to do with your success, the strength of your bond, and the speed at which you get things done. So I wouldn’t look to Nexabond or any particular adhesive to solve problems of bond strength. You’ve gotta solve those through good craftsmanship. And there’s just no getting away from that, whatever the adhesive is. And that good craftsmanship is partly about knowing how the chemistry of your adhesives work, and giving that particular chemistry what it needs to do what it does. It’s very rare that a glue bond failure is about a chemical failure. It’s us.
So I think Nexabond is a very interesting glue, I think it’s worth playing with, but I wouldn’t put furniture out into the world relying on the Nexabond glue unless you’ve spent enough time personally with it in tests, because you’re creating a variable in your environment that no one can tell you about or tell you whether or not Nexabond is going to succeed within those variables.