Glueing up a chair

[dgadams]

So I get a call from a friend of a friend that "understands" I do some woodworking and can I fix her dining room chair? The glue is still drying on the latest project so I think why not. So I told her I'd take a look, and see if I can fix it. The chair was waiting for me this evening. It looks to be maple with a cloth backed seat. The whole thing is put together with dowels and about 75% of the joints have failed. A few taps of the hammer and I've got about a dozen pieces laying around. Pulled out the glue and glued and clamped the whole thing back up. Total time about 45 minutes. The chair looks to be

40 to 60 years old and I'm wondering what type of glue would have been used in factory made chairs of that age? The old glue in the joints is light brown and has a shiny crystalline appearance. I'm guessing hide glue or resorcinol, but don't really know. Ideas?

Also, it's been my experience that trying to reinforce an old chair by putting in some nails or screws doesn't work very well. Anybody have any suggestions?

D.G. Adams

[Andy Dingley]

Probably hide glue. Anything pre-war and anything that wasn't going for that "brave new world" '50s plywood look would still have been hide. The new glues were appearing post war, but it was mainly in lamination that they were being used.

Hide. Resorcinol is darker and doesn't have that "shattered toffee" look of old hide.

Fix it exactly the way they built it. Half-a-century is a good life for any chair without needing some repair, so they must have done somethign right.

[DonkeyHody]

I've had good success using polyurethane glue in similar situations. The expansion of the glue helps fill any gaps so the joint stays tight. Wait until the glue dries and carefully chisel away any excess that foamed out of the joint.

DonkeyHody "Even an old blind hog finds an acorn every now and then."

[Bob S]

Myth Buster #77:

Poly glue certainly does foam out and it does expand - but - the expansion is nothing but weak walled bubbles (look closely) and does not add any measurable strength to the joint whatsoever. Gap filling is best done with epoxy type adhesives. This myth has been covered in a number of articles in the woodworking mags in the past and is easily researched.

Bob S.

[AAvK]

Me not experienced, the first thing I would try is Lee Valley's Veritas chair doctor glue:

the text, that's what it's made for. I am surprised no one else has mentioned it by now!

[dgadams]

Thanks. Your shattered toffee description is exactly what this stuff looks like. There was enough bare wood showing that I used regular yellow glue and put the chair back together exactly as it came apart. My choices of glue were limited to yellow and polyurethane. Epoxy would have been good, but I don't have any at the moment. The chair glued up well and seemed tight this morning when I pulled the clamps off. I hope the joints hold up with use.

DGA

[DonkeyHody]

Bob, I've read those articles too, and I've used more than one bottle of poly glue. I understand that the expanded glue has very little tensile or shear strength, but it certainly fills the inevitable voids in a joint that has worked loose. These joints typically have good contact on part of their mating surfaces and the poly will grab very well there. I believe the expanded part helps keep the joint from wiggling, which adds strength.

I completely disassembled and reglued six 1950's era kitchen chairs for a friend who weighs over 250# They've been in daily use by his family for five years years since then. I asked him a few months ago how they were holding up. He said they are all still tight with nary a loose rung anywhere.

Have you ever tried it in this application?

DonkeyHody "If ignorance is bliss, why aren't more people happy."

[Bob S]

Never have used poly on gluing any old chairs back together, only hide glue and epoxy and then only when needed for a hidden repair, like a partially broken dowel. I have used poly on a number of other applications and know full well that the expanded foam has little strength. If the gap is a wide as the thickness of a business card - then you're better off with epoxy. I'm not saying the joint will alway's fail (depends on a number of variables) but the recommendations are to not to use poly for gap filling if joint strength is an issue. The walls of the bubbles have minimal strength. Poly's strenght comes from the bonding action and by wetting the wood prior to applying the poly, it allows the poly to be forced into cell structure of the wood when the parts are pressed together and the curing starts.

Obviously your chairs must have had good tight fitting joints if they have not failed in 5 years. Do an experiment and drill a hole in some wood and then sand down a piece of dowel so it's undersized and has a gap all around when placed in the hole. Mist the wood, apply the poly and clamp. Now do the same again but be sure the dowel is a snug fit in the hole. Make the dowels long enough so you can get your hand on them to wiggle and pull them and break the joint. Which one do you think will fail first? Do a 3rd hole, undersize the dowel again and use epoxy this time (even the 5 min variety will work for this experiment).

Bob S.

[DonkeyHody]

Bob, I'll agree that epoxy is stronger and fills gaps better. But epoxy is a pain to use and I think poly is strong enough for the application. You are certainly free to disagree, just don't try to make me look like a fool for suggesting it.

DonkeyHody "We should be careful to get out of an experience only the wisdom that is in it - and stop there; lest we be like the cat that sits down on a hot stove-lid. She will never sit down on a hot stove-lid again---and that is well; but also she will never sit down on a cold one anymore." - Mark Twain

[Bob S]

Damn,

Didn't try to make anyone look like a fool. Simply stated what has been stated many times here before. If you don't believe that, then do some research of your own. Let's get the info straight so the OP isn't confused. Some poly's, like System 3's, are advertised as gap filling and all the poly's I've ever tried also foam out and will fill a reasonable sized gap. The poly can be sanded and finished but the foaming action makes for weak, honey-comb like walls which have little strength. So if the joint has a gap, and it needs to be strong, then your best off using epoxy as the adhesive. If strength is not an issue and you want to fill the gap with something, then poly glues are an option but so is yellow glue and sawdust.

Bob S.

[dgadams]

As the original poster I wasn't confused. I had already glued up the chair before even sending the original post My main interest was in identifying the original glue used on the chair and the group was most helpful in pointing me to hide glue. I understand the properties of the various modern glues, but this thread has been interesting and I thank everyone for their input. Actually the original hide glue had held for 50 years. I really need to try some of the stuff on an appropriate project.

DGA

[DonkeyHody]

Research? You mean I gotta do research before I dare to answer a question around here? If research is the answer, let him do his own. The guy asked for personal experience and I told him about mine. Then you charge in with your "mythbusters" and "research". I got no time for this. I'd rather make sawdust.

DonkeyHody

[Bob S]

What a pissy attitude. Do us all favor and go make some sawdust. Come back when you have your head screwed on right.

Bob S.