When I design a piece of furniture, I try to pretend that all the glue inside it will disappear one day, leaving only the wood and metal bits behind. Will the piece fall apart? If the answer is yes, then I have some more work to do.
I arrived at this approach after years of studying old vernacular pieces and campaign-style furniture pieces in particular. These pieces assumed the glue would be destroyed by weather, heat, moisture, time or insects. Or perhaps the builders didn’t have any glue on hand.
Either way, quality old pieces had joints that were reinforced with wedges, pegs, nails, wire, screws, special hardware or other interlocking wooden bits. And so I try to do the same whenever possible.
This approach is in direct opposition to one of the first lessons I was taught in woodworking school: A good glue joint is stronger than the wood itself. I embraced that religion for many years until I got my hands on a bad batch of glue. Then a second bad batch.
Yes, there are bad batches of glue out there – including protein, epoxy, CA (so-called “super glues”) and PVA (yellow glue). If you haven’t encountered bad glue then you have either been really lucky or you haven’t been woodworking for long. Bad glue can come from the factory, or it can be something you created by abusing the adhesive.
After seeing some work of mine fall apart years ago because of glue failure, I turned my back on relying exclusively on glue ever again. Yes, I use glue. It’s cheap and there’s a good chance it will last a long time. But I always have the following soundtrack playing in the back of my mind: “What if the glue goes away some day?” Or here’s another song: “What if I didn’t apply the glue perfectly and clamp it just right?”
So now when I glue up chair seats, I include loose tenons in the edge joints. And I peg those tenons, too. If I can wedge a tenon, I’ll wedge it. If I need to attach a back panel, I’ll use quality nails (cut nails or Roman nails) to do the job. If I can peg (or drawbore) a mortise-and-tenon joint, I’ll peg it.
After I’ve explained my approach to glue to students, some have gone whole-extremist-hog and stopped using glue entirely. I think that’s a mistake. Glue is cheap. Good glue will last a long time and can be reversible and reparable. It’s an enormous asset to woodworking.
But you shouldn’t build your reputation on it alone.
— Christopher Schwarz