A few weeks back I promised a panel glue-up primer… and today is the first time I’ve needed to glue up a panel since. The basic stock prep for the panel pieces is the same as the rest of the prep, until it comes to sticking the two (or more) pieces together. So that’s where I’ll pick up. And as always, it’s best if you can surface your lumber then do any glue-ups within a few hours. The less time the wood has to move, the better – even if you’ve properly acclimated it.
If I’m using yellow glue or liquid-hide glue (which is almost all the time), I rip both edges of pieces for a glue-up; I want those outside edges flat and level so the clamps have a good, parallel surface on which to close. If I’m using hot hide glue and doing a rub joint (which is almost never), there are no clamps involved, so the outside edges don’t matter.
Regardless of my approach, the first steps are the same. Lay out the panel and mark it with a cabinetmaker’s triangle.
You want to joint the edges so that you cancel out any non-perfect-90° angle from your electric jointer or jointer-plane work. If you’re jointing by hand, match-plane the two while clamped together in your vise. This will cancel out any error in your angle. If using a electric jointer, mark one edge “I” (inside) and the other “O” (outside). I runs against the fence, O runs not against the fence. This cancels out any error in the jointer’s fence.
I carefully joint each mating edge, fairly slowly, and at the same, steady speed. Then I immediately proceed to glue up.
Let’s dispense with the rub joint first. For a panel glue-up, the only glue I’d use for a rub joint is hot hide glue (though some sources will say other glues work, too). With the two mating edges freshly jointed, simply coat both edges – quickly – then rub those two edges together lengthwise until the glue starts to gel, doing your best to keep them aligned across the thickness. Then set them on end against a wall and give the glue time to completely dry. No clamp necessary. (The few times I’ve glued up panels this way, I’ve left them a little thick so that I can level the glue line after, and not end up with a too-thin panel. Typically, I use the tack-ability of hot hide glue only for glue blocks and veneer.)
I use liquid hide glue (preferably the the Old Brown stuff) for most things in woodworking, but for typical panel glue-ups, I reach for the yellow stuff. It sets up more quickly, so the clamps can come off after 30 minutes (which means I can get more glue-ups done more quickly – and every minute is precious when prepping stock for classes).
I’ll have a glue-up station ready to go on my bench before I bring stock in from the machine room, usually with a piece of paper underneath an odd number of clamps, because I always want one in the center (and if my prep is good, I can dispense with putting every other clamp on top of the panel). Along with the glue bottle, I have a bucket of water (hot water if I’m using hide glue) and a rag.
First, I run a bead of glue down the center of one board.
Then I spread it evenly with my finger (which is fast) or with an old toothbrush (which is slower but less messy).
I want enough glue that I can rub the wet edge on the dry edge and get enough glue on the mating board that its edge is also fully wetted. But no more than that.
Then I wipe the excess glue off my finger before tightening the center clamp. I keep a finger or two of my non-clamp hand on the seam so that I can feel if I need to exert downward pressure on either board for a perfect mate. (Usually, doing the glue-ups immediately after prep obviates this problem.) I don’t tighten all the way – just enough to hold the joint closed as I repeat at both ends. Then I snug them in the same order until the joint is fully closed and I see a line of glue beads down the seam. That tells me the joint is closed tightly enough, and that I used enough (actually, just a tiny bit too much!) glue.
Next I reach for the bucket and rag, and with an almost-completely wrung-out rag, wipe off the excess glue with small circular motions along the seam. Rinse, re-wet and re-wring the rag often (you don’t want to simply spread thinned glue over the surface). And don’t forget to do the other side. You’ll have a little squeeze-out under the clamps, but it’s easy enough to knock off with a scraper, chisel or plane after the glue is completely dry. Note that none of us in this shop has ever had a problem with glue-size interfering with finishing. Any residual glue is planed away.
The last task is to check the clock and write the time on the edge of the panel. After 30 minutes, you can take the clamps off and move on to the next glue-up. With multiples, I usually stack them up to dry (another reason to remove the glue on the surface), and let them sit overnight before ripping to final size and squaring the ends.
I know there are all kinds of charts, studies and special clamping doodads to help you achieve ideal clamp pressure. I’m sure those are useful. For someone. Me? This simple approach has served me well for more than a decade.
— Fitz
Good overview on Glue-Up. Thanks Fitz.
Meghan , Just curious. Have you ever tried this with fish glue? In guitar making I usually go for that when hot hide glue is impractical. I use it also hot. I store it in the fridge, so it needs to be warmed anyway, and like you, I usually forget it. Sometimes hide glue temperature. Cus-sed sticky stuff, though, either way. ELF
I’ve never tried it with any animal other than cow (as far as I know). But I love the fancy-ass word for fish glue, isinglass.
The sturgeons thank you.
Hi
Thank you for your panelgluelesson.
cold applicable fishglue as we buy it in Paris is said to come from Canada but does not contain much fish in analysation. It contains Thio Ureum which is not very healthy. Isingglas is not proper fishglue but Sturgeonglue which is very strong even dilluted and almost clear.
I have one tip to add to the lesson. When jusing Sashclamps of Iron put some plastic sheat over the gluejoint in between wood and metal to prevent from staining the wood. Especially with Tannous woods like oak.
I wax the metal rails of the clamps to protect the clamp and the work. About half of my work is in Oak and I have not had a problem with discoloration. However, I have had problems in the past with pipe clamps rust staining the work, despite being waxed. I do use a physical barrier when using pipe. Just my experience; not trying to rain on your parade. 🙂
Thanks for pointing this out. The Norland (and the like) fish glue that LV and others sell has little in common with Isinglass glue, which is great stuff, though very expensive!
Isinglass is a sheet of mica, used for windows. Must be a brand name.
Thank you, for a swell article. I’ll follow your advice.
That’s a perfect line of glue beads. Little things like that still make me happy.
Wish I could find wide boards like that!
How does your approach change with multiple boards to glue up in a panel? Is that a not so simple glue up?
I’m a beginner and I struggle to get a tight joint along the 4 ft boards I’m working with. I’m thankful to have used liquid hide glue though because I been able to take my failures apart and try again.
The easiest approach would be to glue two boards, let that dry, then add the next. But try gluing up your next 3+ board panel immediately after surfacing the wood, and see if that makes it easier (the seams should be easier to align because (hopefully) nothing will have yet moved0. Another option is to have a friend on hand to help align as you tighten the clamps, or vice versa, or to do it alone as best you can, then use a mallet to try to knock a high board down where it belongs. On the ends, you can add an F-style clamp at the seam to pull things together, though this approach might still leave you with a hump in the middle (grab that mallet!). And if you’re having trouble with bowing (say from too many tight clamps), clamp top and bottom instead on only on the bottom. You could also leave the boards just a hair thicker than you need them, thereby giving you enough wiggle thickness to plane them to flat afterward and eliminate the problem in post production, as it were.
Completely off topic Megan, but thank you! You really made my day today.
When if ever do you spring the joint?
Michael,
I use spring joints when:
1) I am low on clamps and high on panels that need assembly
2) When gluing up large tabletops. A spring joint ensures the joint will close. Even with a few clamps.
This joint has been around for centuries and is durable.
I use the plastic tabs used to close bags of bread to spread glue on narrow things like a board edge. For larger areas I use something I have lots of: old floppy discs.
WB8NBS. de N2OK
QSL
Megan, you are not expected to understand this.
Guess I botched that typing,
Great article! Do you ever use a vice with bench dogs for glue ups? I glued up some panels 6 pieces wide, 5/16” thick with a caul pined on the vice dog hole. I find it much easier to keep the boards aligned with my left hand while turning the vice screw with my right. I can then put bar clamps over the cauls for added pressure.
Fitz did you just Flip Off the readers during your spreading of the glue episode
Of course not! I was flipping off the photographer 😉
Uhhhh. Thanks?
Regarding panel glue ups.
Do you let the panel sit and for how long before planing / machining to thickness. I ask because I understand, perhaps incorrectly, that there can be creep due to the edge absorbing some degree of moisture from the glue. I have felt, in my glue-ups, what I thought was a perfect, seamless edge, over the course of a few days, become one edge higher than the other. I try and wait a few days before sanding or machining to final thickness so the joint itself stops moving and distributing moisture.
Felt like a good place to ask about this. Thank you!
I know less than nothing about woodworking, but it was interesting that you specified to tighten the center plank first. This is in sync with the proper way to tighten bolts when working on cars – start in the center, and move to the edges. On cylinder heads (think a 3×5 grid of 15 total holes) you start in the middle then go ’round in a spiral. The idea is, if you bind up the edges first, you may still have some bow, and clamping the middle later will make for a double-bowed interface. If you don’t follow “manifold pattern” on cylinder heads, it’s even odds you’ll have leaks.
Kinda cool to see mechanic stuff and woodworking intersect!