glue for wood - waterproof

[TiggerToo]

Which glue would you recommend for an oily wood (iroko), to join pieces in a way that is water-proof?

 

[srp]

Epoxy resin, something like SP106 plus microfibres as a filler. It's the only adhesive I use for marine work, and I do a fair bit of laminating with iroko (deck beams, knees, tillers etc). A wipe with acetone or meths will help if the wood feels oily.
Most of the replacement parts I have made have been glued with Cascamite (or whatever they call it these days) which always fails along the glue line.

 

[reeac]

Epoxy. I understand that a big plus point for epoxy is that it isn't too fussy about conditions [surface finish, slight gaps, humidity etc].

 

[sailorman]

Iroko is nothing like as "oily" as teak & i have never degreased it.
i would prefer to use Cascamite
http://www.axminster.co.uk/cascamite-powdered-resin-wood-glue-prod21688/

http://www.boatdesign.net/forums/wo...xy-versus-cascamite-compatibilities-4025.html

Which glue would you recommend for an oily wood (iroko), to join pieces in a way that is water-proof?

 

[tillergirl]

And just to confuse you further - Semperoc a PU one part glue. Fresh nice new iroko, I would use epoxy. Used iroko which has been exposed to damp, weather etc, I would use (and have) Semperoc. See http://www.eastcoastsailing.co.uk/ECS07-low.pdf

 

[macd]

Foaming polyurethanes are excellent (my preference is Balcotan), have great gap-filling properties and relish a degree of moisture. (In fact chemically they're two-pack, using moisture in the air or in the wood to promote curing).

However for external boat work on clean, dry surfaces I'd prefer a solvent-free epoxy thickened with microfibres, as srp suggests. This works well on iroko. Like any adhesive, the greater the surface area of the bond, the better -- whether by scarfing, pegging or jointing. Although for bonding (as opposed to coating/laminating) epoxy isn't much fussed about high humidity (since air is excluded), most epoxies don't like damp wood. Some water-based epoxies can handle wet wood, but that's a bit esoteric for the OP's purpose.

 

[TimBennet]

Foaming polyurethanes are excellent (my preference is Balcotan), have great gap-filling properties and relish a degree of moisture.

No, no, no, no! The glue might foam up and 'fill' the gap with bubbles, but the strength is massively reduced. PU glues need a good fit and clamping.

Only thickened epoxy is truly gap filling and that's why you can fillet joints with it.

As said, iroko isn't oily like teak (although the grain can make it tricky to work) and you don't need to 'degrease'. But epoxy isn't really tolerant of poor conditions and it shouldn't be assumed you will get a good strength bond in sub optimal conditions.

 

[sailorman]

100%
no glue will compensate for poor workmanship
PU is very messy but is a useful glue & does (often) leave a glue line, unlike cascamite

No, no, no, no! The glue might foam up and 'fill' the gap with bubbles, but the strength is massively reduced. PU glues need a good fit and clamping.

Only thickened epoxy is truly gap filling and that's why you can fillet joints with it.

As said, iroko isn't oily like teak (although the grain can make it tricky to work) and you don't need to 'degrease'. But epoxy isn't really tolerant of poor conditions and it shouldn't be assumed you will get a good strength bond in sub optimal conditions.

 

[xeitosaphil]

Which glue would you recommend for an oily wood (iroko), to join pieces in a way that is water-proof?

A lot depends on where it will be used and it what circumstances. If the joint will be under stress from a bend say, or if it will be fixed with no movement, also if it will be used in a wet environment..
Timber is a moveable quantity and is effected by moisture even teak will expand and contract. As said by others epoxy is good if not in contact with too much moisture, Cascamite is ok inside, foaming glues are ok if you don’t want tight joints with no signs of a glue line. There are lots of glues available but you also need to look at where they will be used IMO
Where there is no moisture present solid glue lines if covered with a water proof top coat epoxies etc will be fine, but a solid glue line with moisture is going to break as the wood will expand and break the glue line. In this case you would be better using a sealant/ adhesive such as Sikaflex or Saba Sealtak which will bond but will also allow movement.

 

[srp]

Most of the replacement parts I have made have been glued with Cascamite (or whatever they call it these days) which always fails along the glue line.

Just re-read this and it is ambiguous. I have made replacement parts for customers who have brought me the originals to copy - the last one was a laminated Sigma tiller. Most of the breakage of the original was caused by the glue failing, and it was Cascamite. While I have used it in the past, there are so many better alternatives nowadays, I see no reason to recommend it. It is far too brittle to withstand the constant timber movement associated with boat components and damp winter/dry summer conditions. Cured epoxy has a much greater elasticity, and if mixed and used correctly will always be stronger than the wood itself.

 

[macd]

No, no, no, no! The glue might foam up and 'fill' the gap with bubbles, but the strength is massively reduced. PU glues need a good fit and clamping.

Only thickened epoxy is truly gap filling and that's why you can fillet joints with it.

Yes, yes, yes
PU is indeed good at gap-filling (and is widely advertised as such), although you're quite right about the mechanical consequences, which is why we both advocated thickened epoxy.

Incidentally, you seem to have a habit of talking a lot of sense.

 

[TimBennet]

PU is indeed good at gap-filling (and is widely advertised as such), although you're quite right about the mechanical consequences,

I'm sorry, but you can't call something 'good at gap filling' if the joint is both porous with the bubbles and much weaker than expected.

The advertising of PU glues as 'gap filling' is widely regarded as being, at best, 'mis-leading'.
But it's actually worse than that, an people who have thought of PU as an alternative to a true gap filling adhesive like epoxy, have come spectacularly 'unstuck'.

 

[Amulet]

I love Cascamite, but note that it does not claim to be waterproof - just kind of "nearly" . It did change its name though (Extramite?).

Epoxy, as said, is the business, and I'd even go so far as to say that it CAN compensate (to a fair extent) for poor tool work. Thickened up with microfibres or sawdust it will strongly fill gaps in poor joints. It is fussy about curing temperature, which can be a nuisance in the winter in the UK.

To be fair on PU, it will do cosmetic gap filling - which is sometimes all you need. It is wonderful for some things. It will cope with damp subtrates and doesn't even mind being frozen. If it is adequate to the job in hand I use it - the main reason is that it doesn't blunt your tools planing up etc afterwards. If you're planing up something laminated with epoxy you spend a lot of time sharpening.

 

[Niander]

Yes i noticed its only weather proof
so what happens if dunked underwater?
like in a bilge OP wants waterproof...

 

[rogerthebodger]

Cascamite (Urea-formaldehyde) is not submersion proof OK for damp conditions. Until Epoxy and PU the glue that was used when submersion proof was required was Cascophen (Resorcinol-formaldehyde). I use mostly PU and if I need it to fill gaps I mix saw dust with it and using saw dust from the wood you are working with makes the joint difficult to see.

My local PU is white in colour but I also use Balcotan

More info here http://en.wikipedia.org/wiki/Wood_glue