Waterproof wood glue

[robgraham]

I'm repairing an old teak garden folding bench seat. The slats for both the back and seat require replacing.

The seat slats aren't giving me any bother, but the back slats are loose tenoned into two horizontal timbers which would require major dismantlement to remove. I've tried removing one of these slats by bending to see if that would be the way to get new ones in, but it just broke.

My thinking now is to cut away the back of one of the mortices with a thin saw, slip the slat in and then re-glue the cut out piece, but am wondering what glue would best. Waterproof PVA exists but cannot be relied on if the wood is permanently damp - PU I don't fancy and it also has caveats against it. The DIY Wiki doesn't give any clear guidance on this.

Suggestions ?

Rob

[Bob Minchin]

What is your problem with PU

As far as I'm concerned it is perfect for this sort of job and I've been using for 'always damp' type conditions for years.

Bob

[Rob G]

It will expand and A) push the insert out of place B) with its expansion, it will end up sticking the slat in the loose mortice. The DIY Wiki raises questions on it's 'always wet' capability.

Rob

[Cash]

Rob,

Be aware that teak is a very oily wood and very few glues will adhere to it without some sort of 'special' preparation for the glue to 'stick'.

Have a look at this link which seems to have some useful info.

[Rob G]

Thanks for that, Cash. I hadn't thought of the oil problem, but it does seem as if a bit of oil removing fluid just before application solves that one. The link you gave is useful too. Rob

[The Medway Handyman]

You need a D4 grade adhesive as used in boat building.

[polygonum]

Is there any readily accessible site which provides a very simple potted summary of what on earth EN204/D4 actually defines?

So far it is like all the other standards which manufacturers claim to adhere to. Just an identity to quote.

[Bob Eager]

[John Williamson]

Good grief, are they still making that?

[Bob Eager]

It came up a while ago, and I checked then. My dad used to use it for canoe building. In fact, he used it for everything!

[Rob G]

It is the glue that I had in mind, and I think I have some somewhere, but wanted to get some opinions. Certainly the difficulty of gluing oily teak, and the solution, was something I wasn't aware of.

I built a car - actually van - body with cascamite, or it's precursor in the mid 1960's. Again to be actually totally accurate, my father did the building and I was the apprentice, but now, well past the age he was then, I can appreciate that it was that point in fatherhood where the son is someone you can work with and pass on your DIY knowledge.

Rob

[NT]

You can always use epoxy. Its the glue of choice for timber when failure would cause an accident. If you wrap a sandwich bag round the end of the slat, that will prevent it getting glued too. Its totally

100% waterproof, you can immerse it in the sea for 50 years and it wont mind. Its also very tough stuff.

PU's fine if it dries out fully, but if it stays wet/damp, mine turned to jelly after a month. It gets used for outdoorish timberwork, so... who knows, it may well be fine.

NT

[F Murtz]

Titebond 111 maybe

[Andy Dingley]

Epoxy on teak.

PVA isn't waterproof enough, even the posh stuff.

PU is crap, expensive, a pain to work with, weak against repeated fretting loads (chairs, single column tables) and useless against UV

Cascamite is nice, but doesn't work well on fresh teak or iroko (to a slightly lesser extent). De-oiling with meths, or it just being a couple of years old, helps.

Most "teak" you buy in timberyards these days is iroko. If you are buying teak, it's mostly illegally logged in Cambodia and then whitewashed through the Malysian government sawmills (they have more sawmills than forest, but claim it's all for home production). Best avoided.

[Bolted]

The McDonalds of glue.

[Andy Champ]

Yes, my dad used to use it too. But he gave up and switched to epoxy about 20 years ago. As did every boat builder and repairer I know.

Epoxy is enough stronger that the jointing fillets in some old designs are now omitted, and there's a struggle to make the boat heavy enough to conform to class rules (light is fast). It also lasts a lot longer.

Andy

[Bob Eager]

My dad stopped a bit before that. He spent many years using glass fibre too, in a not very well ventilated area.

He eventually died of oesophogeal cancer. I sometimes wonder if there was a connection.

[Andy Champ]

Epoxy doesn't have a good name for safety. Gloves are advised - though AFAIK breathing the fumes isn't an issue.

Andy

[Rob G]

Thanks for all the replies.

I remembered sometime after posting this that at some point in my wood working activities I had been told the solution to this problem is to deepen the mortice in the upper timber of such an assembly such that the replacement bar can be slipped far enough up to drop into the lower mortice. Job done. I was replacing all the seat slats so was able to recycle some of the undamaged ones into the back rest so that at least looks original.

Deepening the mortice made me think a bit and try various options as access wasn't that easy. The effective solution I hit on was a milling cutter in the battery drill - very controllable and easy for access - a form of router I suppose, but slow enough speed not to chew out to much wood.

Rob