I'm repairing a solid teak dining chair and was planning to use regular PVA wood glue to fix a split stave (child stood on it grrr..).
As it is clearly a very 'oily' wood I'm wondering if PVA is actually the best solution? Anyone any ideas?
TIA
Removing the oil with acetone is recommended immediately before gluing and then an epoxy glue
So would araldite be OK ??
PVA is not recommended for apps where failure would cause significant risk, such as a chair. Araldite is a good deal stronger setting than araldite rapid, the quick set sacrifices a lot of strength.
NT
Excellent advice.
West System is widely used in the marine industry and one of the best epoxy products about:
There are various types, so a check with the manufacturer would be a good idea.
Another option is polyurethane glue such as Gorilla glue or Titebond III. These need careful clamping
With care though, as unlike with PVA, you can squeeze too much epoxy out of the joint. West System is good stuff.
A light sanding is supposed to be more effective than an acetone wipe, according to some bloke in FWW who did a test a year or two ago. Epoxy gave the best results in his tests, but there wasn't that much wrong with either PVA or PU, IIRC.
Thats the way I would go, acetone & Titebond 111. Polyurethane glue is easy to get off timber afterwards but a right bugger to get off your hands.
Sanding may be good for surface contaminants, but I'm not sure it would improve glue bonding to a naturally oily wood like teak.
I agree about polyurethane glues, but (as Andy already said) it's absolutely essential to very firmly clamp the surfaces together as it goes off.
PVA - it's convenient, easy to use, easy to clear up - but nowhere near the equal of polyurethanes or epoxies.
I'm just reporting the results of some bloke's empirical test, in which he found that sanding with a fine grit improved the bond, and acetone did nothing. I haven't done one myself.
As a good PVA joint is stronger than the wood itself, this rather suggests that wood should not be used for chairs.
Sorry, Fine WoodWorking, a US woodie mag.
Oh no.... Fine Woodworking. A very good publication even though it does originate from Septica.
PVA will "work", but not to the strength you're likely to need in a chair (do you need it to be capable of kid's step-ladder duty afterwards?)
De-oiling teak is snake oil. It makes a big difference for hide glue, but the joint is still weak. It makes little difference to PVA. The real improvement comes from simply using a glue such as epoxy or PU that doesn't care whether it's oily or not.
PU is over-rated crap and has no place in furniture making. You're forever fighting against it: it's either foaming everywhere you don't want, or it's turning out to be uselessly weak because there was the slightest gap in it. The problem of overspill alone is enough to rule out PU on furniture.
Your best option is epoxy (this is true for a lot of structural woodworking). Don't use Araldite as it's too viscous (and too expensive!). Instead treat yourself to a West System sampler pack (about 15 quid from Axminster). This is a _real_ epoxy, of good quality. It's a low viscosity resin to begin with, and it's unthickened. This makes it far more useful overall than two-tube mixes like Araldite (standard or rapid). Every uk.d-i-y reader ought to have one of these kits - I use about one a year. The various filler powders are worth trying out too, but not for this job.
Hi Andy
Interested in your opinion. I have used PU several times to sovle a embuggerance problem & its saved my arris. Granted it foams all over the place, but when dry that scrapes off pretty well.
I like it a lot, so could you elaborate on your experiences please?
I'll take your advice & get one next time I pop into Axminster Sittingbourne.
First of all, you're right about the scraping. Dry scraping after curing works a lot better than any atempt at wet cleanup. Even then though, you're not going to do this cleanly on something that already has a finish on it (i.e. furniture repairs). With the foaming behaviour of PU, even using a low-foam glue and working it to reduce foaming, you _will_ get some overspill.
For carpentry, rather than joinery or cabinetry, I've also been disappointed with it. The main problem is short service life - give it a year or two and things are wobbling. Whether this is stress cycling or UV failure I'm never sure, but I've just lost faith in trusting it long-term. Gap-filling performance is useless, to a level that would require excess care when cutting mortices. If there's any sort of gap involved, the joint is too weak to survive. I can fill gaps with Titebond (and that's no gap filler) that just don't work with PU.
The fillers are worth having too. I use a lot of mine mixed with either microballoons (if I want to sand / scrape it) or fibres.
A recent test in FWW, showed the surprising result that poly glues were in general poor compared to PVA based ones for most applications.
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