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
Is that first picture a panel there? When I read this I immediately thought about panel glue-ups and how to reinforce them for a glueless future
Yes. Those are seat blanks.
I think what the picture is showing is that those loose tenons (dominos) are used with the seat blank panels and then pegged.
The only flat panel glue-up I ever had to split at the joint was glued up with dowels. Took it about a year. Never reinforced a panel glue-up again. Never had another fail in 50 years now.
There seems to be a strong movement right now that insists glue is fine by itself, even for joinery. Some folks are just always going to be contrary. I can’t imagine relying on glue alone.
I wonder about the future of modern homes. So much in them relies on adhesives. It’s a little disconcerting.
The quality of construction adhesives vary tremendously. The claims of capability and application can be from conservative to outlandish. The majority of the time I have had to facilitate repairs on ‘stuck on joinery’ was due to inappropriate use, lack of mechanical anchors or not enough and just plain shoddy workmanship and construction overcome with a quick fix which holds long enough for the resultant issue to be an SEP (somebody else’s problem).
The really good ones which hold and have flex to allow for wood movement can be so strong as to destroy timber which may need removing for other associated repairs, maybe a bit too good at their job. They can have their place, with consideration.
Can you expand a bit on pegging loose tenons. I’ve tried thin nails but don’t have much faith in them. Are barbecue skewers your go to tech ? Something else ? Thanks
I like bamboo skewers. They are cheap and very strong. But not historically appropriate when working on old-style pieces. For those, I rive out oak pegs and drive them through a dowel plate.
Bamboo skewers it is ! Thanks
Fantastic anarchist point considering the trend among manufacturers and woodworkers has been to cut corners on construction. So are bamboo skewers stronger, cheaper than 1/4″ dowels?
That’s a pretty good approach Chris. I have to say in 30 + years I can’t recall a glue failure due to “Bad” glue but my memory is starting to wane and who knows maybe it failed after it was shipped and installed and never knew.
I have most definitely had failures due to improper application and or clamping, had a few early on when I first started to do veneer, there was no practical internet (at least accessible for me) so it was learn it the old way, figure it out as you go and learn from your mistakes, “armchair woodworking” wasn’t available at the time…
When you peg those loose tenons with bamboo skewers are they drawbored or just pegged? I am assuming just pegged since you have two per side for each tenon if I understand the positioning in your picture correctly.
For a chair blank, they are just pegged. For a workbench top, I will drawbore. I do this by first pegging one side while the top is apart. Then I can glue and drawbore its mate. Hope this makes sense.
It makes perfect sense. Thank you.
Thank you for addressing a fact of woodworking that has been long overdue from both writers & instructors. No offense to you & yours! I was fortunate enough to learn this fact as I started my career as a restorer & the majority of repairs always consisted of loose or failed glue joints in furniture of all ages. Just as the US Navy operates, nothing leaves my shop unless it’s been constructed with redundancy.
Thanks to those whoever worked in the military. My dad is USMCR but worked as a civilian at Naval Air Systems Command in Air Survivability – talk about redundant systems!
I tend to find myself being a “belt & suspenders” kind of wood worker to. If I were to use loose tenon joints, aka dominos, but I don’t own a fancy Festool domino cutter, how is the best method to accomplish this? I am also assuming the loose tenons are glued before pegging.
Thanks
Imagine there’s no adhesion
It’s easy if you try
No MDF below us
Above us, only sky
Imagine all the people
Sittin’ in stick chairs
You-hooOOOooo…
Haha.. excellent!
Imagine all the glue joints
Failing over time…
Youuu
You may say I’m an anarchist
But I’m not the only one
I hope some day you’ll join us
And the hand and power tool shops
Will live as one
I’ve come to the same conclusion. Though when it comes to table tops, I still want to believe I can get by with just glue. But right now I’m finishing a table with a top that has no pegged loose tenons, and I’m not at peace. If I had a domino, it’d be an easy choice. Or if this was a chair seat. Ive reinforced a table top with pegged loose tenons before, and it was a lot of extra work chopping all those mortises in white oak! The customer who commissioned the current table would like butterfly inlays (alas, a feature I’d like to distance my work from). Maybe I’ll just go all out and inlay an entire kaleidoscope of butterflies in the top. At least this way all the extra handwork will be seen. Would you extend your mechanical joint resolution to table tops as well?
All this information will stick with me for a long time.
I just recently had an unpleasant surprise with the short shelf life of epoxy. Standard, simple PVA is much better in this aspect, although it can turn bad as well.
Belt and suspenders, I say. Overkill is both fun and satisfying 😉
Please allow me to ask a point of clarification. Drawboring a workbench top, as I will be embarking on this glue-up soon. Is this procedure similar to that of a mortise and tenon of a leg and stretcher. That is to say the peg holes of the tenon are slightly ascew, maybe 1/16″? Thus, the mating holes of the second blank of the top are ascew to the first. Then once glued and joined, cauls are applied to bring the top and/or bottom surfaces coplanar? I had always thought biscuits, but knew that they are more for alignment of anything.
You have it right. Glue and peg the tenons onto one surface. Then drawbore it into the second surface (1/16″ to 3/32″ offset id fine). You probably won’t need clamps to bring the surfaces flush – the tenons do that. But you might consider clamping ACROSS the joint like you would a normal panel. It makes assembly easier.
Is there a certain seat or size threshold? Would you recommend this approach for your low staked stool, for example?
Except in emergencies, I try to incorporate a mechanical interlock with edge joints. In an emergency, that can be a spline.
What I am advocating is overkill. And I am not trying to push this sickness on others. Most edge joints will outlast their maker.
What are Roman nails? Thanks
Nails that are square in section and tapered on on all four surfaces. Blacksmiths make these nails, as does Rivierre (sold by Lee Valley).
You can buy them directly from Rivierre at clous.eu too (at least if you’re in Europe, can’t say if it works outside of it).
When using glue, be very mindful of shelf life, and do not mix types or manufacturers on the same joint.
I make things without using glue all the time. The trick is not telling anybody. They’ll never know.
I wonder if another thing to consider is whether a joint is cross grain or not? Edge jointed boards with parallel grain are going to “breathe” in and out together over time.
But a table apron or most mortise-tenon pairs are going to expand at 90* to each other year in and year out. A chair rung must do both (and more) in its 360* run around the grain track—maybe why they seem like the first to go?
Good argument for repairable glues on anything intended to last for decades—along with Chris’s mechanical lock joints.
A woodworker named Bob Smalser posted loads of info on this with glue tests years ago… some of it may still be floating around.
…Words to Live by!
I am late to the game here, but I will ask anyway — could one do some sort of pegged ship lap? I’m not super excited about dominoes, but I enjoy making rabbets.