Glue Question

[Robert11]

Hello,

I posted this a few days ago, but it apparently never made it to the group ? Funny, this has never happened before. If this ends up being aduplicate post, I apologize.

--------------------------- Hello,

Have a real old wooden bed frame that is in pieces, that I would like to put back together.

It was originally held together by very large Biscuits, and a few Dowells, it appears.

Re the biscuits:

a. Should I use an epoxy glue, or perhaps that Gorilla Glue which I think they call an acrylic adhesive ? Which would be better ? Why ? (anything even better these days ?)

b. Some of the biuscuits have old, very hard, dried glue on them.

Would either the epoxy or Gorilla glue work (well) if I don't go to the trouble of sanding them clean ? Or, must I really get rid of the old stuff before either would grab ? (looks like a lot of work to try and sand them clean)

Thanks, Bob

[Jim Yanik]

"Robert11" wrote in news:M5idnaT_FsYPwCXbnZ2dnUVZ [e-mail]:

here's a repeat of my answer;

Polyurethane glues are not meant for gap-filling applications. Biscuits(new ones) are meant to swell from moisture in the glue,to be very tight mechanically in addition to the glue bond. Glue Epoxies do not get absorbed into the wood,and have a weaker bond than a glue like Titebond.Clamping can also squeeze out too much epoxy,weakening the joint.They do fill gaps nicely,and would work better with the old used biscuits,as the old biscuits have a glue coating that would prevent absorbtion of a polyurethane or Titebond-type glue.

it would be better to use NEW biscuits(or make a spline) and Titebond. (biscuits are cheap,and worth it.)

Wood Magazine recently did a test on biscuit/dowel joints,tested their relative strengths and ease of use. They also have done glue tests.

you also need to remove the old glue from the biscuit slots or dowel holes,as the old glue will prevent the new glue from soaking into the wood.

new glue is not going to bond well to old glue.

[Frank]

I responded too and your post confirmed my suspicions that Gorilla glue is a polyurethane since it foams on curing. Titebond sounds like the standard type polyvinyl acetate as is Elmer's glue. I would use them but epoxies should also work and there are probably grades made for wood.

[Jim Yanik]

Frank wrote in news:svudnavgr9llASXbnZ2dnUVZ [e-mail]:

Titebond is quite a bit better than Elmers Glue(white glue),and there are thick,non-drip and waterproof versions of Titebond(II and III).

boat fiberglassing epoxies will be thin enough to soak into wood but need fillers(like wood flour,chopped glass,chopped plastic fiber,fumed silica,phenolic microballoons) added to use as a glue.You first apply the unfilled epoxy mix to soak into the wood,then add fillers for gluing.

System Three has an inexpensive (~$10 US PPD) trial kit (epoxy,several fillers,mix cups and sticks,and a piece of fiberglass)that is very nice,comes with the Epoxy Book(also downloadable)that is a must-read. West Systems Epoxy is also very good,and personally,I use RAKA epoxy. I started out with the System Three trial kit.It's WELL worth the money.

S3 and West epoxies are widely available,usually at woodworking stores and marine supply stores.

[dpb]

Robert11 wrote: ...

Some advice already --

How old is "real old"?

If biscuits are original that indicates more than likely 20s-vintage at the earliest and machine, not hand produced.

The glue to use depends in part on what is there but the the general advice of cleanup is sound.

Assuming the joints are original and not something already hacked on, if you can take a hot, wet cloth and soften the glue, that would indicate a hide glue which is certainly one possibility. In that case, going that route as a repair would make sense.

Otherwise, if it is nonsoluble in water/heat, cleanup and dry fit as well as possible, particularly to ensure dirt and years' of crud aren't in the way. If the biscuits are larger than a current new one, depending on what they actually are, you may be able to fabricate replacements relatively simply from thin ply stock. Otherwise, cleaning them before reuse is about the only reliable technique.

After that, if not using hide glue, I'd recommend any of the current PVA wood glues--on a clean, well-fitted joint they're as strong as the wood in well over 50% of joint tests so there's no need for anything stronger than that.

I recommend against epoxies or polyurethanes (gorilla, et al.), resorcinol, etc., as simply unneeded for the job and making additional repair/restoration down the way if required nearly impossible, not just difficult.

--

[Phisherman]

I would clean off all the old glue. Dry fit, fuss with clamps, use yellow woodworking glue (such as Elmer's), clamp, allow to dry overnight, sand, refinish. If that's too much work, I'd reconstruct replacement pieces. Why did it break? I wonder if the frame was made properly in the first place and not worthy of repair.

[<nni/gilmer]

I always figured that was one of the advantages of that type of glue. It would expand to fill gaps.

I don&#39;t like it because it&#39;s quite messy but I&#39;ve used it anyway just because of the "gap filling."

[charlie]

it fills the gap, but isn&#39;t very strong across the gap. it&#39;s sorta like a foam.

[dpb]

Well, one would think so, but surely you&#39;ve noticed that one the things that makes it mess it is foams -- the gap is filled w/ the same way -- it&#39;s mostly air w/ only a tiny amount of glue making up the bubbles. So, you really end up with the worst of both worlds -- the gap isn&#39;t solidly filled so it doesn&#39;t finish well and (at least in that area) the joint isn&#39;t very strong.

Obviously the best answer is to make well-fitting joints but for gap-filling, choose something other than the polyurethanes (epoxies w/ fillers, etc.). The only time I really would recommend p-u&#39;s is for locations that really require the fully waterproof nature or for an application perhaps requiring the long open time during assembly I _might_ consider it (although w/o the waterproof requirement it would be pretty far down my list of alternatives probably).

--