|| Tip Index
Talk to me about glue. As you all know in chair making you don't always get
all the joints real tight. And any round tenon joint is half short grain.
Add to this the tremendous stress that chair joints are subject to and glue
joint failures are inevitable I've been using yellow woodworkers glue with
good results. But what about the long run? Is old fashioned hide glue any
better? Some guys use nothing but epoxy. I heard of one guy who uses an
automotive gasket sealer because its thick and never hardens??? Any comments
on glue would be appreciated. JJ 4/25/04
REPLY: I've always used elmers white glue for all chair joint except glueing seat blanks together, where I use titebond yellow glue. The most important reason for me is the white glue doesn't get brittle when dry. It ends up just slightly flexible or rubbery, a good thing in a airdried wood assembly. It also seems to have a little longer working time and it's never failed. JT 4/26/04
REPLY: ....The white glue has the advantage of setting up more slowly. It is convenient and ready to go out of the bottle. It is the glue I use to build up all the upper sections of my chairs.
Yellow glue("wood glue") has a faster set up time which can present problems if you are glueing a bunch of things at one time.
Both of these glues give the chairmaker a strong glue to work with and they are very inexpensive. According to the literature at 2 different glue suppliers, they claim the yellow glue gives a stronger joint than the white and water does not break it down as easily as the white. ?? I avoid the waterproof yellow glues for the same reasons I avoid epoxy: how do you repair a joint if you can not break down the glue?
Drawback(opinion): You can not repair a joint assembled with alphatic glue UNLESS you completely remove the old glue before reglueing. New alphatic does not grab old brittle glue. Repairs yellow and white glue joints on the under-carriage are very difficult.
Hide Glues: What the old timers used. Some builders today don't like the glue pot and the double boiling preparation. In my opinion, the hide glue from the bottle has far too much gelatin in it to keep it in the liquid form and this detracts from the overall strength when applied. In the hide glue family you will also find fish glue. This glue is sold as a surface preparation for windsor makers to "crackle the milk paint finish" when mixed a certain way with water. This is also an excellent glue to use in chair assembly. It dries slowly and the claimed tack is equal to the white glue. Hide glue is easy to repair. I know there is a tremendous amount of attention given to building chairs "under tension" and I use this method but joints can dry up over time and fail. Hide glue does not have to be removed to repair it. I have drilled a pin hole in the leg mortise and injected hot water followed by fresh hide glue and the joint has been good for another 10 years. No dis-assembly.
Epoxy: No place in this man's chairmaking shop. The stuff is great for boat building and other applications but it just makes repair work impossible. I would rather deal with a nail in the joint than epoxy. This brings tears.DO 4/26/04
REPLY: I still rely primarily upon what I believe to be the mechanical forces of wet-dry joinery, of legs stretched apart, and wedged tapered joints, so to me there are only a few joints where glue really matters - glued up seat blanks and arm paddles or knuckles come to mind. I use Titebond on the seat blanks, and I use a couple of #20 biscuts about 3/8" deep in the underside of the seat. I know they're a modern thing but they form a mechanical joint after they expand and I like that. On the arm paddles, I use Gorilla glue. I have found it to be the strongest glue for that particular purpose. Since I have it around, I use yellow Titebond for all the other joints. I don't seem to have a problem with it setting up too quickly, but I put chairs together a lot quicker than when I started, and I started with Elmer's white glue. BG-WKG 4/26/04
REPLY: I appreciate DOs remarks regarding his needs, but the question seems not to be what folks like to use and hope will work, but what glues are best scientifically for a windsor chairs specific joints. Now I want to preface my remarks by saying Im not a windsor chair maker and have never built a windsor chair of any kind. (Im a period cabinetmaker and aerospace engineer, for what its worth).
The PVA glues, (yellow and white glues) all require high bondline or clamp pressure to generate full bond strength. The manufacturer of Titebond glues, Franklin, recommends 150-250 psi of clamp pressure minimum to develop bond strength, (depending on the specific glue and materials). I e-mailed Franklin and asked for test results for joints with little or no clamp pressure. They didnt respond with numbers, but felt very little strength would result.
So any joints where clamp pressure cannot be applied (mortise and tenons, round or otherwise) are NOT good candidates for PVA glues. In the short term we may get away with PVA in these applications, but it wont last, isnt a strong bond, and is difficult to repair. For these joints a glue with good gap filling properties is required. There are only two such glues commonly available: Epoxy and hide glue. Additives can be added to either to get the open/work time and elasticity required for the Windsor chairs unique assembly. I understand how this sort of alchemy has been deemed impractical by some builders.
Interestingly, the old timers belief that rough joints (like a rough sawn tenon) held better than two smooth surfaces is correct when the glue used is either epoxy or hide glue. The rough sawn, or irregular surfaces help to maintain the required bondline and stop the glue from extruding out of the joint. Good news for we sloppy workmen who produce gappy joints!
It is my understanding that some Windsor chair makers use tapered tenons in matching tapered holes in the seat-to-leg joints. (I use that joint too, but for other applications). While I have no way of knowing for sure, my guess is that a good rap with a mallet could easily generate the minimum pressure required for the use of PVA glue in this specific joint. Moreover, the line-to-line type fit makes this joint ill-suited to epoxy or hide glue (which will extrude out). You could score the tenon with a vee gouge to make a splined dowel type joint if you wanted to continue using epoxy or hide glue for these joints.
So just to sum up, anywhere you have a gappy joint or cant produced a near crushing pressure with a clamp, youre better off with epoxy or hide glue. If you are forcing a joint together, like a really tight set of dovetails or a tapered tenon, hide glue and epoxy will extrude out, so you may be better off using PVA. AC 5/4/04
REPLY: In your description of alphatic glue use in a "non-clamp" application one consideration you might be overlooking is the wedge. True the tapered leg tenon contributes to the pressure of the final fit in the matching mortise but.. the wedge driven in the tenon adds to the outward pressure on the mortise. I would guess equal to the reasonable force of a bar clamp on an edge joint.
Hide glue: Its still being used. You have to wonder: how has all of the 18th century joinery held up so long with this easy to repair glue? It seems like some good stuff after all these years. In most cases where I have introduced skeptics to hide glue they have been impressed with the ability to put a rub joint together with the hide glue with simple hand pressure. I have used this demo and come back the next day to break the joint at the glue line and it just doesn't happen.
Lingering Question: Each time I wedge a spindle and give it a good tap I wonder if there is any glue left in the joint? Well its not keeping me up at night I think the mechanical joint is "kicking in" at some point. For the chairmakes out there who have found a good thing that works for them, its hard to change. Why change when you have success? So we keep building and improving in our effort to build that chair just a little bit nicer each time. Its fun. So is the Chair Talk forum. DO 5/5/04
I've recently started using hide glue on my chairs. I've put together
three chairs and I'm pleased with the end result. But it is a real mess getting
there. I'm experiencing a great deal more clean-up on the chair and it must
wait until the glue has cured to do it. Unlike poly vinyl acetate that can
be cleaned up with a damp rag, as this stuff cools it turns to "snott" and
stays that way until the next day. Is anyone out there using hide glue and
how do you deal with it? FRS 8/23/04
REPLY: I'm curious- why use hide glue? It seems as though you are going through a lot of pain, especially if the goal is simply to be faithful to the 18th century. Since hide glue is so much inferior to our glues today, using hide glue does make it more likely that some future owner will notice his attention to 18th century detail- when it becomes necessary to re-glue the chair!
The joints in a Windsor chair all have means other than glue to keep them together. Which is why 18th century chairs are still around. Hide glue turns brittle and the bond is broken the first few seasonal swell-shrink cycles. I heard Mike Dunbar say the glue is only there to keep the chair from squeaking, fill in the gaps as it were. GB 8/25/04
REPLY: Hide glue is generally considered to be superior to PVA glue in terms of clean up. Heres why: Depending on conditions, hide glue drips can be simply peeled off. That area can be finished without additional treatment (sanding, scraping,etc) even with water based milk paint.
Now this contradicts your statement, but maybe I can guess why. First, my experience is only with hot hide glue, not the liquid stuff in the bottle. I dont know if its different. I just have no experience with it.
Hide glue gells in my shop in about 20 minutes. At that point, drips will peel right off of the wood. If you try too early, and the glue is still runny (you used a different word, I think), it will make a big mess. A thin film of wiped hide glue is the worst to clean up. That may have been your experience. So wait a little longer next time. You could try (brownie test) sticking a sharp awl in a drip. If it comes out clean, you know the drips are ready to peel. Also, hide glue is so strong, you can accidentally pull glue out of a gappy joint when peeling off runs. In these instances, I slice around the joint with a knife first. Removing dried hide glue is really nasty too. I wear eyeglasses and they have saved my eyes on several occasions as chips soar from the tip of my chisel. Dry hide glue is really glassy and brittle, so be careful.
Lastly, weve had a discussion here on the merits of hide glue before. I couldnt disagree more with the comments of GB. Hide glue has comparable properties to modern glues. That said, I suggest windsor chair makers not abandon PVA entirely, but rather use different glues in different joints (as I do). You can go back and read the conversation and decide for yourself.
Of all of the benefits of hide glue, repairability is perhaps the most attractive. Hard to know if furniture made with PVA will outlive us. Fine furniture of the 18th century survives, despite its well documented construction flaws, in part because it can be so easily and effectivley repaired. PVA joints cannot be repaired by adding more PVA.
When copying highly successful furniture that has been cherished for 200 years, it can be difficult to know exactly which attention-to-18th-century detail to skip? 20 years ago, chair makers skipped tapered tenons in their chair seats. AC 8/25/04
REPLY: Much has been said on the site about glue benefits in each of the categories. When discussing hide glue, most assume the builder is using "hot hide" from the pot. I don't like premixed hide glue for the same reasons I don't like premixed shellacs of any kind. You just don't know the mix and how long the stuff sat on a shelf before you use it. The investment in hide glue is so little its worth getting some and trying it out on some simple joints and seeing how it works. I do like the stuff and I use it on a regular basis. I think the option of being able to reset a joint by adding new hot glue is a real benefit if a repair should come up. Food for thought.D.O. 8/26/04
REPLY: I to am curious as to why hide glue. From my experience the only real advance we have today for chairmaking is the glue. I find it hard to improve the designs and joinery from the traditional but plain old white elmers is a wonderful improvement over the old glues. The white glue seems to never get brittle so always has some flexibility. My only experience with hide glues is seeing old furniture where many joints have let go. It's holding power didn't seem to last very long. JT 9/1/04
| GLUE TIP:
I have been reading with interest and sometimes
amusement everyones rantings and ravings about glue. So I've got to add my
two cents worth.
First of all chair joints are the worst things in the world to glue. A round tenon in a round hole. Half of the joint is short grain...it just doesn't glue good. They are usually anything but good tight fits. There always seems to be gaps no matter how careful your are. And last, the joints on chairs, above all other kinds of furniture, are tortured to death every time someone sits in them. They are twisted, racked and strained to death. That's why chairs fall apart. So the hell with being historically correct or in making it easy for some guy to repair 100 years from now.....use the best glue you can get.
Old fashioned hide glue....not the pre-mixed bottled kind...is one of the best glues around. Every bit as good, if not better, than modern glues. But it is anything but convenient to use. It's a mess and stinks.
I've been using plain old yellow glue with good results. But I recently tried TiteBond's new "Molding and Trim" glue. Now I won't use anything else. It's basically a woodworkers glue but it is thick....about like pudding. It is a joy to use. No more drips and runs. Cuts clean up to a minimum. And it is somewhat gap filling. Drawback is that it sets up fast so you better have your ducks in a row before you start. I have used this on my last six chairs and love it.
When you're trying to put glue in a dozen holes of a C-Arm bow you know what a mess it can be. It either all runs out and all over you, or it all runs to the bottom of the holes where it does no good. With this thick stuff it stays where you put it. Absolutly no drips and runs or sinking to the bottom.
And I don't care that Dunbar uses Elmer's White Glue in class. That stuff is the pits. If you have to have a long open time use TiteBond's "Extend". It's yellow glue with a long open time.
But if you're confident in your skills try the Molding and Trim glue....it's a joy to use.I would appreciate comments from anyone else who has tried it. JJ 10/3/04
REPLY: I'm curious as to why Elmers white glue is "the pits". I've been using it for 10 years, glue failures in over 500 chairs are less than 1% and all but one of them were obviously abused. So I have seen no problems and have no complaints. While the long open time of white glue isn't a bad thing, I use it for it's flexibility. The stuff always retains a bit of give or rubberyness and I think that's it's advantage. Yellow glues don't, they get very hard and brittle. JT 10/5/04
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